The Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CALCULATION OF AERODYNAMIC HEATING OF A CONICAL FOREBODY ALONG FLIGHT TRAJECTORY3182713610.21608/asat.2011.27136ENAhmed, M.Y.Zayed, A.N.Said, M.K.Journal Article20190214The phenomenon of aerodynamic heating is created as a consequence of body-flow interaction. It is originated from viscous flow characteristics inside the boundary layer in the vicinity of body. The adjacent flow temperature increases, leading to an increase in body wall temperature depending on flow regime, surrounding air density, body velocity, wall material, flight time, etc.. The present work provides an illustrative calculation procedure based on closed-form relations. A computer program was implemented to be used as a quick, easy, and accurate calculation tool for the expected wall temperature distribution and its variation with flight time for a conical fore-body during a complete flight at zero incidence. The code was applied on a number of real cases with a variety of flight conditions. Results were compared with<br />published and previous work and showed very good agreement.https://asat.journals.ekb.eg/article_27136_4e02648cf8640aefd884c01758ad4444.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501INVESTIGATION OF MODE SCATTERING BY HARD STRIPS IN LINED DUCTS USING COLLOCATION19302713710.21608/asat.2011.27137ENElnadiT.Assistant Professor, Sound and Vibration Lab., Faculty of Engineering, Ain Shams University, Cairo, Egypt.Journal Article20190214When mounting acoustic liners inside the inlet duct of aircraft jet engines, hard strips exist in-between liner sections in order to hold them in place. It has been generally acknowledged, from experiments, that the existence of hard strips inside lined ducts affects the attenuation behaviour of the duct. The acoustic energy is scattered and rearranged among different modes so that it might be transferred into modes which are less attenuated by the liner. Moreover, cut-off modes may scatter into cut-on modes. In this paper, flow is included in the locally reacting liner case, which is more interesting to the aeronautics applications. Moreover, the duct is made finite and connected to two semi-infinite hard inlet and outlet ducts. By using mode matching, it is possible to input any mode at the inlet side and to study the modes on the outlet side. Comparisons are made between different hard strip cases and the splice-less liner case.https://asat.journals.ekb.eg/article_27137_b8c9eed22d620f6039d4066ef9a584fe.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501APPLICATION OF GENETIC ALGORITHMS WITH THE AID OF PANEL METHOD TO OPTIMIZE MISSILE AERODYNAMIC SHAPE31422713810.21608/asat.2011.27138ENMutawkil A.SulimanEng., Lecturer, Dpt. Of Mech. Aeronautical & Aerospace, Karary Academe of Technology, Khartoum, Sudan.Journal Article20190214The use of genetic algorithms with the aid of the panel method to determine high-efficiency missile aerodynamic shape has been examined. The capability of these algorithms to determine highly efficient and robust missile aerodynamic designs is demonstrated by giving a variety of design variables and constraints. Results indicate that the genetic algorithm is clearly capable of designing aerodynamic shapes that perform well in either single or multiple goal applications.https://asat.journals.ekb.eg/article_27138_bfc0b341d657295314b9441dab2d8ca3.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501THREE-DIMENSIONAL FLOW IN A TRANSONIC AXIAL FLOW FAN OF A HIGH BYPASS RATIO TURBOFAN ENGINE43632713910.21608/asat.2011.27139ENA. F.ABD EL-AZIMProfessor, Mechanical Power Engineering Department, Zagazig University.M. H.GOBRANAssistant professor, Mechanical Power Engineering Department, Zagazig University.H. Z.HASSANDemonstrator, Mechanical Power Engineering Department, Zagazig University.Journal Article20190214The present study deals with the air flow through an axial flow transonic fan blades, found in high bypass turbofan engines. Examples are CF-6, RB211 and GE90 turbofan engines. The fan has a wide chord, highly twisted blades of large span with a mean hub-to-tip ratio of about 0.404. The blades are tapered with its maximum chord at the tip radius. Moreover, these twisted blades have slight reduction in its maximum thickness from hub to tip. Consequently, the flow field is a three dimensional viscous compressible. The engine intake together with the fan resemble the case studied here. The computational domain includes two periodic merged sectors at a central angle of 360 degrees divided by the number of blades (38). The first sector is stationary, which represents the intake domain, while the second is rotating, which represents the fan domain that comprehending one blade. This is an effective way of reducing the calculation time and speeding up the iterations. The investigated model (Intake and fan blade) dimensions and configuration are identified by measuring real dimensions of CF-6 engine fan module. The FLUENT solver employing the Spalart-Allmaras turbulence model is used to solve the flow field in both the intake and fan. The program results represent the variation of the flow characteristics (pressure, temperature, Mach number, etc) in the flow field at the design condition (cruise conditions; namely, 11000 m altitude, 0.85 Mach number and 3674 rpm fan speed). The fan performance map was also predicted for a range of percentage fan corrected speed from 60% to 110%.https://asat.journals.ekb.eg/article_27139_c0bee785c5e50c47c410ca54d037e8c2.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501PREDICTION AND CONTROL OF FLOW ASYMMETRY OVER SLENDER CONICAL BODIES.65802714010.21608/asat.2011.27140ENHamdy. A.KandilMechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, 21544, Egypt.Hassan. A.WardaMechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, 21544, Egypt.Alaa. A.El-MeliguiMechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, 21544, Egypt.Wael. A.AzabMechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, 21544, Egypt.Journal Article20190214The supersonic locally-conical flow over a 5° semi-apex circular cone at a Mach number of 1.8 and angles of attack (AOA) ranging from 10° to 35° is studied computationally using the three-dimensional Navier-Stokes equations. An implicit upwind flux-difference splitting scheme was used to obtain the numerical solution of the governing equations. Three flow patterns were predicted depending on the AOA. These flow patterns are; steady symmetric flow at AOA = 10°, steady asymmetric flow for 15° AOA 25° and unsteady asymmetric flow with vortex shedding for AOA ?. 30° . A number of passive control methods including vertical, fixed or erected, fins, two side strakes and four strakes in two different arrangements, oblique and cross, are used to restore the flow symmetry over the cone. A comparison between the studied control methods is carried out to select the best method of control. The four cross-strake method was found to be the best of the tested control methods.https://asat.journals.ekb.eg/article_27140_e3a02ffdd4766b088eb1e46f2c3f9832.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION OF OPEN CAVITIES FLOW811052714110.21608/asat.2011.27141ENN. N.BayomiFaculty of Eng., Mataria, Helwan University, Cairo, Egypt.A. M.Abdel DayemFaculty of Eng., Mataria, Helwan University, Cairo, Egypt.Journal Article20190214Computational and experimental investigation was performed for an incompressible flow over an open cavity. A cavity of a unity length-to-depth ratio was considered at Mach number 0.1 and a moderate Reynolds number of 3.18x105 based on cavity depth. Different geometries of square and skewed cavities were taken in consideration to investigate their effect on the back flow pressure. The measurements were established for a two dimensional cavity in a wind tunnel of 30 m/s flow velocity corresponding to the considered Mach number. Both the pressure coefficient and the drag coefficient were estimated for the considered geometries. In addition, a numerical simulation of the cavity flow field was developed. A numerical solution of the Navier-Stocks equations was carried out for the incompressible two-dimensional and turbulent flow. The equations were descritized by a finite-element scheme using ANSYS 5.4 code. The flow was fully demonstrated over the cavities considered, acceptable agreement was obtained between the measured and numerical experiments. Moreover, it is found that the square cavity has a less pronounced effect on the back flow than other geometries. The results were verified with the corresponding published data.https://asat.journals.ekb.eg/article_27141_54d49a8ffc120a29c66854894f28ae43.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501COMPUTATIONAL SIMULATION AND EXPERIMENTAL VALIDATION OF DOUBLE SQUARE CYLINDERS FLOW IN STAGGERED ARRANGEMENT1071302714210.21608/asat.2011.27142ENA. M.Abdel DayemMattaria, Helwan University, 11718 Masaken El-Helmia, Cairo, Egypt.N. N.BayomiMattaria, Helwan University, 11718 Masaken El-Helmia, Cairo, Egypt.Journal Article20190214Experimental and numerical study of the flow field around two finite square cylinders in staggered arrangement is the objective of the present work. Two similar cylinders having the same square cross-section of 50 mm x 50 mm with blockage ratio of 16.7% were considered in different arrangements. The staggered arrangement with different angular positions was considered. The turbulent incompressible Navier-Stokes equations are solved numerically using finite element method. The static pressure distributions on the two-cylinder surfaces were estimated and measured in all cases with different apart-distances between the two cylinders and consequently the pressure coefficient variations were calculated. In addition, the experiments were developed for three Reynolds numbers of 13.5, 9.5 and 6.8x104 (based on the cylinder side length) to investigate their effect on the turbulent flow. The upstream cylinder is not affected greatly for different angular positions and apart-distances. This effect is significant in the case of side-by-side, where the flow stream equally affects the two cylinders. Up to four cylinder-widths apart-distance, the upstream cylinder affects the downstream cylinder. The effect is changed from maximum value in tandem arrangement to minimum one for the case of side-by-side configuration. Moreover, where the upstream side of the downstream cylinder is affected by changing the Reynolds number, the other sides do not vary. The highest considered Reynolds number produces the lowest drag and side force coefficient. On the other hand, the computational results are in close agreement with the measured ones. The numerical visualization presents clearly the flow behavior around the cylinders and was validated by the measured and published data.https://asat.journals.ekb.eg/article_27142_21acf9ec6af2e12382ad563daf73447d.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EXPERIMENTAL AND THEORETICAL INVESTIGATION OF DYNAMIC BEHAVIOR OF OLEO PNEUMATIC CAR SUSPENSION1311462714310.21608/asat.2011.27143ENZ. A.IBRAHIMM.Sc. Eng., Egyptian Armed Forces.M. G.RABIEProf., Egyptian Armed Forces.S. A.HEGAZYPh.D, Egyptian Armed Forces.I. A.ELSHERIFPh.D, Egyptian Armed Forces.Journal Article20190214The oleo pneumatic (hydropneumatic) car suspension with self-leveling system is an essential part for any controlled suspension in modern vehicles. Therefore, the performance of the hydropneumatic vehicle suspension has been studied in the present work. A mathematical model for a hydropneumatic suspension composed of hydraulic accumulator, double acting shock absorber and power cylinder has been deduced. The mathematical model has been solved numerically, using the MATLAP simulink program, to predict the dynamic performance of the hydropneumatic suspension. Experimental tests using the MTS damper test system have been applied to validate the results. The experimental testing and theoretical results have been compared; good agreement between them has been found. The developed mathematical model for the hydropneumatic suspension has been applied to a two-degree of freedom vehicle model representing the vehicle body and wheel assembly. The dynamic response of the vehicle body has been obtained. The effect of different construction parameters and working conditions on the dynamic response has been studied in order to obtain the optimum values of these parameters.https://asat.journals.ekb.eg/article_27143_fe3fc6c4b7a800ec6e54d02d591daa3d.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DESIGN AND ANALYSIS OF DYNAMIC PERFORMANCE OF A VEHICLE ACTIVE SUSPENSION SYSTEM1471632714410.21608/asat.2011.27144ENZ. A.IBRAHIMM.Sc. Egyptian Armed Forces.I. A.ELSHERIFPh.D, Egyptian Armed Forces.M. G.RABIEProf., Egyptian Armed Forces.S. A.HEGAZYPh.D, Egyptian Armed Forces.Journal Article20190214In this work, the design and analysis of a hydropneumatic slow active suspension with leveling system is developed. The design based on a hydropneumatic suspension unit with a shock absorber element of an existing car and an electrohydraulic servo valve. A nonlinear mathematical model of a quarter car with active suspension system is deduced. The mathematical model considers the real dynamic behavior of the hydropneumatic suspension unit and the electrohydraulic servo valve. The classical control theory is used to design the control system of the active suspension system, a proportional derivative controller (PD) is used for leveling system control and the proportional integral controller (PI) is used for controlling and minimizing the vertical body acceleration due to the road irregularities. Using the MATLAB tool kit, a simulation program for the designed system is developed. The main suspension disturbances, road irregularities, and the inertial forces are modeled and simulated. The tire is simulated by linear damper and linear spring. The simulation model is used to predict the dynamic response of vehicle body under different types of roads and dynamic loads. The simulation model is also used to compare the performance of the designed active system with the passive system.https://asat.journals.ekb.eg/article_27144_94ed5d0a2e2365a810a1eabbced54a73.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501SUPPRESSION OF VORTEX INDUCED VIBRATIONS ON CIRCULAR CYLINDER VIA BOUNDARY LAYER SUCTION1651782714510.21608/asat.2011.27145ENFAROUK M.OWISAssistant Professor, Cairo University, Aerospace Engineering Department.Journal Article20190214Marine risers used to convey oil from the sea bed to the sea level, marine cables, heat exchanger pipes, civil engineering structures and aircraft wings vibrate due to the formation of the vortex streets behind these structures. The interactions between the flow oscillations and the structure give rise to complicated vibrations of the structure which could cause structural damage due to the fatigue. Numerical simulation of the vortex-induced vibrations on circular cylinders is used to investigate the possibility of suppressing these vibrations for different engineering applications. The unsteady, incompressible, two-dimensional Navier-Stokes equations are solved numerically on a structured grid using the finite difference method. The effect of flow control using the boundary layer suction for fixed or moving cylinder is investigated by applying the appropriate boundary conditions on the cylinder surface. In the current study, natural motion of the cylinder is not considered. Flow oscillations are investigated only for fixed cylinder and for forced motion of the cylinder. The results indicate that the flow oscillations are completely damped for a fixed cylinder using suction on the cylinder surface. For forced motion of the cylinder, the vortex shedding from the surface is eliminated using the boundary layer suction. The flow oscillates only due to the forced motion of the body vibrations which means that the flow oscillations can be damped completely if the cylinder is left to oscillate naturally.https://asat.journals.ekb.eg/article_27145_b46157ed90120193d4e0ba9f694dc9df.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DETERMINATION OF OPTIMUM SLOT IN A BACKWARD VANE IMPELLER FOR BETTER CENTRIFUGL PUMP PERFORMANCE1791982714610.21608/asat.2011.27146ENHussienEAssistant Lecturer, Dept. of Mech. Engineering, Chair of Mech. Power, MTC, Cairo.Lotfy A.H.Associate Professor, Dept. of Mech. Engineering, Chair of Mech. Power, MTC, Cairo.Abdalla H.M.Associate Professor, Dept. of Mech. Engineering, Chair of Rockets, MTC, Cairo.SalehI.Professor, Dept. of Mech. Engineering, Chair of Mech. Power, MTC, Cairo.Journal Article20190214Previous work for the authors proved that the performance of a centrifugal pump with radial vanes impeller could be improved by opening a small slot in impeller vanes, especially when the pump operates at part loads, [1,2]. It is due to transportation of fluid from the vanes positive pressure sides via the opened slots to the vanes negative pressure sides, which reduces the size of the generated vortices in the impeller passages. In the present work, the authors investigate the optimum length and location of the opened slot in backward impeller vanes. The governing equations representing the flow field throughout the impeller passages are solved numerically by using the stream function and the primitive variable approaches. The numerical solution is introduced in a code program using Microsoft Visual C++ 6 language. The flow pattern is represented by streamlines in order to compare the vortex size in case of impeller with and without slots at different slot lengths and at different slot positions along the vane. It is found that the vortex size, at flowrates less than the nominal value, depends mainly upon the length and the position of the slot. The slot length and position are changed gradually until the smallest vortex size is reached. The slot with these dimensions is defined as the optimum slot. The optimum slot is achieved at slot length, Sslot, from 18% to 22% of the blade radial length, Lvane=R2 - RI, and at slot position, Rsioi, from 35% to 60% of the blade radial length, Lvane. In previous work the authors had proved that the pressure fluctuations at pump exit relates to the vortices formation inside the vane passages and their shedding mechanism from the impeller exit. Hence, in order to investigate the obtained results from the present code program, the pressure fluctuations at the centrifugal pump exit are measured and analyzed by power spectrum analysis. The experimental study proved that the pressure fluctuations are affected by the slot location and slot size. The lowest pressure fluctuations have been achieved experimentally when the theoretically determined values of optimum slot location and size are used practically.https://asat.journals.ekb.eg/article_27146_6e1b012eb556457b13cc0c1c38f32a67.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501PERFORMANCE OF OIL-INJECTED TWIN-ROTORS SCREW COMPRESSOR1992192714710.21608/asat.2011.27147ENKASSAB S.Z.Professor, Mechanical Engineering Department, Alexandria University, Egypt.ADAM I.G.Lecturer, Mechanical Engineering Department, Alexandria University, Egypt.ELGOHARY H.A.Graduate Student, Mechanical Engineering Dept., Alexandria University, Egypt.Journal Article20190214In order to improve the performance of screw compressor, it is important to know, understand, and analysis the different geometrical as well as operating parameters on the compressor performance. Consequently, the present study is concerned with obtaining the characteristics of twin-screw compressor by using a simulation code named SCORPATH. Explanation of the code is presented and discussed. A parametric study was performed to determine the effect of the geometrical and the operating parameters on the performance of screw compressor. The study revealed that the geometrical parameters: clearance gap, number of lobes in the rotors, rotor relative length, and screw wrap angle, have significant effect on the performance of the screw compressor. In addition, built in volume ratio, tip speed, suction and discharge pressures, are the operating parameters which have a great effect on the performance of the twin-screw compressor.https://asat.journals.ekb.eg/article_27147_1e08cbc2649ce1ecf77c4ae0694d624d.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EXPERIMENTAL INVESTIGATION ON THE INFLUENCE OF MUZZLE BRAKE GEOMETRY ON AUTOMATIC SMALL ARMS PERFORMANCE2212362714810.21608/asat.2011.27148ENMoghazy M.A.Egyptian Armed Forces.Journal Article20190214Fully automatic weapons have a short history, yet their inspection and methods of improving performance and accuracy of fire have been largely limited. Most of weapon performance parameters depend directly on the design of muzzle brake. The object of this work is to provide automatic small arms with a muzzle brake of a suitable design that would reduce its recoil velocity. This will reflect on the enhancement of the weapon performance. A number of muzzle brakes of different configurations have been manufactured and tested. The target was to predict the muzzle brake efficiency, and the fire accuracy. The test device permits the evaluation of the recoil of small calibre rifle by measuring the maximum number of recoil parameters at the same time. Measurements included the time variation of recoil force and accelerations for mechanical vibrations (horizontal and vertical) for an automatic rifle 7.62 x 39-mm, without and with muzzle brake. Furthermore, the projectile muzzle velocities, accuracy of fire and dispersion have been measured. It was found experimentally that the recoil velocity of the rifle could be reduced by about 35 %. Improvement of dispersion and accuracy of fire could be reached through the suitable design for muzzle brake. This work may contribute to solving problems in design and selection of muzzle brake geometry in automatic small arms with different calibres to enhance the weapon performance.https://asat.journals.ekb.eg/article_27148_b4909394e6803325db25d132d6392fc8.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EXPERIMENTAL INVESTIGATION ON CONTROLLING OF MUZZLE BLAST WAVE IN AUTOMATIC SMALL ARMS2372502714910.21608/asat.2011.27149ENM. A.MoghazyEgyptian Armed Forces.Journal Article20190214Muzzle blast wave in small arms represents special problems for many applications. They may be attributed to supersonic flow of the discharged propellant gases from the barrel muzzle after the projectile departure. Herein, experimental investigation of controlled and uncontrolled blast wave has been carried out under different working and design parameters. Different silencer design theories were carried out, to control the blast wave in both subsonic and supersonic cases, which produced from automatic small arms. The pressure-time history of gases discharging from an automatic rifle 7.62 x 39-mm was measured for different mass of propellants. In addition, recoil force for the rifle without as well as with silencer and the projectile muzzle velocity has been measured. Results showed that, for different mass of propellants in ammunition and suitable design of silencer, the sounds could be reduced by about 90 percent. In addition, silencers reduced recoil energy by about 20 percent. Also, the silencer efficiency increases by decreasing blast wave pressure as well as mass of propellant of ammunition decreasing.https://asat.journals.ekb.eg/article_27149_86a3988400f9f28d54adb5c5462a03c5.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DESIGN OPTIMIZATION OF COMPOSITE ROCKET MOTOR CASES USING GENETIC ALGORITHMS2512672715110.21608/asat.2011.27151ENEI-Geuchy M.N.Egyptian armed forces.Zayed A.N.Egyptian armed forces.El-Maddah M.M.Modern Academy in Maady.Journal Article20190214A new tool for designing a solid propellant rocket motor casing made of composite materials is obtained by merging the genetic algorithm optimization method with the finite element method. The genetic algorithm optimization method is used to determine the best design parameters of the laminate to minimize the weight of the rocket motor casing. The ANSYS finite element code is used to analyze the overstressing strength of the rocket motor casing. Tsai-Wu failure criterion is used to assess the first ply failure and an overstressing load level factor is introduced to describe the failure strength. Practical design examples, of composite rocket motor casings, are investigated using the present design tool.https://asat.journals.ekb.eg/article_27151_24afcf1cf4c5e27ce2b187fb3fe776fd.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EXACT SOLUTION OF ARBITRARILY LAMINATED COMPOSITE BEAMS USING A HIGHER-ORDER THEORY2692852715210.21608/asat.2011.27152ENA. OKASHAEL-NADYAerospace Research Center, A01, Cairo, Egypt.Journal Article20190214Analysis of arbitrarily laminated composite beams is presented based on a higher-order shear deformation theory. The governing equations are derived by minimizing the total potential energy of arbitrarily laminated beams undergoing axial and transverse shear strains under laterally distributed load. The exact solution of the governing equations is presented for hinged-hinged beam. The displacement and stresses of several laminated beams are calculated and compared with published results. The results of a parametric study showing the nature of axial and interlaminar shear for various ply-stacking patterns, beam aspect ratios and transverse shear are demonstrated.https://asat.journals.ekb.eg/article_27152_6d3c7baa137a48c8d0be9172e681a454.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501BALLISTIC RESISTANCE OF FLEXIBLE COMPOSITE (KEVLAR-129/LINE-X xs 350)2873012715310.21608/asat.2011.27153ENA.FayedEgyptian Armed Forces.E.ElawadEgyptian Armed Forces.M. S.AbdelkaderProf., Arab Academy for Science, Technology and Maritime Transport.Journal Article20190214The use of textile and flexible composites for the containment of high-speed fragmentation is well established; the design of body armour, fragmentation curtains and bomb blankets are end products, routinely deployed. In this paper an experimental program is conducted to test a new composite material of (3D-weaveTM Kevlar-129/ LINE-X xs-350), which is a two-component spray-in-place flexible 100% solids Polyurea/Polyurethane system. Ballistic response of this new composite is compared to that of (3D-weaveTM) Kevlar-129; the multi-layered targets of the two materials are subjected to impact by 7.62x39 mm normal projectiles in the velocity range of 300-450 m/s. The average energy absorbed per one layer of the new composite and Kevlar targets is calculated. Calculations show that the composite targets are generally more efficient than the Kevlar targets in defeating impacting projectiles. Moreover, post firing examination of Kevlar/line-x targets shows recoverable behaviour and localized damage after the ballistic impact; this means small trauma effect in case of using this composite as body armour.https://asat.journals.ekb.eg/article_27153_1b04b0fe6b81f218244fdb23bea40dea.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A SUGGESTED NUMERICAL ALGORITHM FOR GEOMETRICALLY NONLINEAR AEROELASTIC BEHAVIOR3173382715410.21608/asat.2011.27154ENMohammed Elhadi AhmedElsayedPhD., Assist. Prof., Karary Academy of Technology – Khartoum – Sudan.Journal Article20190214A numerical simulation algorithm has been developed to investigate the effects of geometric nonlinearities on dynamic aeroelastic behavior of wing-like cantilever structures. A geometrically nonlinear finite element formulation relevant to flexible structures has been adopted to model the structure using a degenerate-continuum shell element along with total Lagrangian formulation. Subsonic doublet lattice method (DLM) has been used to model the unsteady aerodynamics. To ensure full coupling between the structural and aerodynamic networks, infinite plate spline technique has been employed. This has facilitated the transfer of loads and displacements during the nonlinear analysis where the aerodynamic load is applied incrementally through a unique two-level time stepping procedure developed in the present work. The results obtained highlighted the effectiveness of the suggested numerical algorithm in capturing geometrically nonlinear behavior. Geometric nonlinearities showed additional nonlinear features that are not predicted by the linear approach.https://asat.journals.ekb.eg/article_27154_ddb42e107f59406ae479ce7224f32d9c.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501FLUTTER CONSTRAINT FOR AIRCRAFT CONCEPTUAL DESIGN USING RESPONSE SURFACE METHODOLOGY3393502715510.21608/asat.2011.27155ENAHMED A.MOHAMEDResearch Engineer, Aerospace Research Center, Cairo, Egypt.GALAL B.SALEMProfessor, Department of Aerospace Engineering, Cairo University, Giza, Egypt.ATEF M.HASSANEINProfessor, Department of Aerospace Engineering, Cairo University, Giza, Egypt.Journal Article20190214Flutter constraint, applicable to aircraft conceptual design, is constructed using response surface methodology. It is presented by the critical flutter speed, as a function of wing torsion stiffness, root chord, sweep, mass ratio, taper ratio, aspect ratio, center of gravity location and radius of gyration. The constraint function to is a quadratic response surface polynomial. The D-optimal design is used to find the best combinations of design points required to determine the function coefficients. 'The Regier number criterion is used to calculate the critical flutter speed at these design points. Analysis of variance is used to remove the unreliable terms from the function. To match the Regier number criterion, two constraint functions suitable for subsonic aircraft with traditional wing are constructed. The first one is applicable to aircraft with low sweepback wing while the second one is applicable to aircraft with moderate sweepback wing. As a case study, the constraint function is applied within the conceptual design of a subsonic aircraft leading to a considerable weight saving.https://asat.journals.ekb.eg/article_27155_8c4e768f5e84d418db98defd17c4d2c8.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501THERMAL DEFORMATION ANALYSIS OF MICROSATELLITE STRUCTURE3513722715610.21608/asat.2011.27156ENGasserAbdelalPh.D., Deputy Group Leader - Satellite Structure (EGYPTSAT-I), National Authority for Remote Sensing and Space Science (NARSS).AymanAtefSenior Structure Engineer - Satellite Structure (EGYPTSAT-I), National Authority for Remote Sensing and Space Science (NARSS).Journal Article20190214Mounting accuracy of satellite payload and ADCS (attitude determination and control subsystem) seats is one of the requirements to achieve the satellite mission with acceptable performance. Components of mounting inaccuracy are technological inaccuracies, residual plastic deformations after loading (during transportation and orbital insertion), elastic deformations, and thermal deformations during orbital operation. This paper focuses on estimation of thermal deformations of satellite structure. Thermal analysis is executed by applying finite-difference method (IDEAS) and temperature profile for satellite components case is evaluated. Then, Perform thermal finite-element analysis applying the finite-difference model results as boundary conditions; and calculate the resultant thermal strain. Next, applying the resultant thermal strain, perform finite-element structure analysis to evaluate structure deformations at the payload and ADCS equipments seats.https://asat.journals.ekb.eg/article_27156_892efb28f26617c956be2ee679e59232.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DESIGN, ANALYSIS, AND RELIABILTY OF SOLAR PANEL ROTATION MECHANISM FOR MICROSATELLITE3733932715810.21608/asat.2011.27158ENGasser F.AbdelalPh.D., Deputy Group Leader - Satellite Structure, National Authority for Remote Sensing and Space Science (NARSS).MohamedKassabSenior Structure Engineer - Satellite Structure, National Authority for Remote Sensing and Space Science (NARSS).Journal Article20190214Solar array rotation mechanism provides a hinged joint between the solar panel and satellite body, smooth rotation of the solar array into deployed position and its fixation in this position. After unlocking of solar panel (while in orbit), rotation bracket turns towards ready-to-work position under the action of driving spring. During deployment, once reached the required operating angle (defined by power subsystem engineer), the rotation bracket collides with the fixed bracket that is mounted on body of the satellite, to stop rotation. Due to the effect of collision force that may alter the rotation mechanism function, design of centrifugal brake is essential. At stoppage moment micro-switches activate final position sensor and a stopper locks the rotation bracket. Design of spring and centrifugal brake components, static finite element stress analysis of primary structure body of rotation mechanism at stoppage moment have been obtained. Last, reliability analysis of rotation mechanism is evaluated. The benefit of this study is to aid in the design of rotation mechanism that can be used in micro-satellite applications.https://asat.journals.ekb.eg/article_27158_795a50f05415e97a449a3c99b171ea26.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501LIFE PREDICTION MODELING UNDER FATIGUE LOADING FOR ALUMINUM METAL MATRIX COMPOSITES3954102715910.21608/asat.2011.27159ENAbdellatif S.H.Assistant Lecturer, Dept. of Mech. Engineering, Chair of Mech. design and
production MTC, Cairo.Shoukry M.KAssociate Professor, Dept. of Mech. Engineering, Chair of Mech. Mech. design and production MTC, Cairo.Rabeeh B.M.Associate Professor, Dept. of Mech. Engineering, Chair of Auto. MTC, Cairo.Journal Article20190214Metal matrix composites are currently being considered for use in many applications for their high strength-to-weight and stiffness-to-weight ratios, high wear resistance, and high thermal resistance. The present work focuses on the study of crack propagation in Aluminum monolithic and aluminum metal matrix composites reinforced with continuous stainless steel fibers at 4%, 8%, and 13% volume fractions with five plies, and unidirectional structural configuration. Based on experimental evidence, a micromechanical modeling approach was developed for the prediction of fatigue life and the model was compared with actual fatigue lives for these materials.https://asat.journals.ekb.eg/article_27159_238bd85edbc666edfe136cd2b7914b73.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501MODELLING OF MONOPROPELLANT SPACE PROPULSION SYSTEM4114252716010.21608/asat.2011.27160ENA. A.HashemAssociate Professor, Aerospace Dept., Cairo University, Giza, Egypt.Journal Article20190214Monopropellant thrusters still have a role to play in orbit insertion of small satellites whenever a sizable thrust is required. A new preliminary design analysis methodology is adopted. Two monopropellant catalyst bed reactor models are employed. The first model divides the flow into liquid, liquid-vapor, and vapor regimes. Each regime is divided into pore and free stream levels. This model is basically used off line to estimate the liquid phase regime behavior. A second model, which assumes the propellant to be readily vaporized, is used to predict the performance of the vaporized regime grossly on the free stream level. The analysis is conducted for a blow-down type feed system. A case study is presented employing hydrazine as a monopropellant. The results point out a collective impact of the tank pressure on minimum system mass. The optimum tank pressure is influenced by the bed loading and blowdown ratio. The technological complexity may have a vital impact on the choice of the bed loading and blowdown ratio.https://asat.journals.ekb.eg/article_27160_b4048a8084e4cdb8c85f11a51e13baff.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DESIGN AND TESTING OF THE IGNITION SYSTEM FOR HYBRID ROCKET MOTOR4274402716110.21608/asat.2011.27161ENFAROUK M.OWISAssistant Prof , Cairo University, Faculty of Engineering, Aerospace Dept.Journal Article20190214The design of an efficient and reliable ignition system represents a challenge for propulsion engineers especially for hybrid rocket motors where the fuel grain and oxidizer are separated. In the current work, a simple design model is used to size the igniter, and to select the solid propellant type and mass. The analysis is based on the heat transfer model of the main rocket motor grain, thermochemical model of the ignition process and an empirical regression rate model of the grain. Following this analysis, a design point of the igniter including the chamber pressure, igniter dimensions and a propellant type are selected to perform the required task and to ensure the ignition of the main engine. Series of experiments are performed for different propellant types, different propellant mixture ratios and different grain size to select the optimum igniter. The flame length, temperature and ignition time are observed to assess the performance of the igniter. Finally, the selected igniter design is tested successively in the hybrid rocket motor.https://asat.journals.ekb.eg/article_27161_c96a195758477d5e4ab20f53e2eca362.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DESIGN OPTIMIZATION AND GEOMETRIC ANALYSIS OF THE SLOTTED SOLID PROPELLANT GRAINS4414622716210.21608/asat.2011.27162ENZayed, A.N.Egyptian Armed Forces.Journal Article20190214Three different categories, of the slotted solid propellant grains, are optimized from the point of view of the configuration parameters. The optimization process, of the main dimensions and the length ratio, is built on the conditions of filling coefficient and clamping factor. The grain geometry is analyzed to calculate the burning perimeters through the web thickness as a tool to predict the burning performance during the burning time. The effect of the length ratio on the performance of the burning perimeter is investigated to obtain the optimal length ratio for each configuration.https://asat.journals.ekb.eg/article_27162_d44896427bb3b477096415de41b2b489.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501ATOMIZER EFFECT ON COMBUSTION CHAMBER FLOW CHARACTERISTICS4634782716310.21608/asat.2011.27163ENOlaRashedProfessor, Cairo University, Faculty of Engineering, Aerospace Department.BadieaHafezAssistant Professor, Cairo University, Faculty of Engineering, Aerospace Department.AntaLPenningerProfessor, Head of the Heat Engines Department, Budapest Technical University.Journal Article20190214https://asat.journals.ekb.eg/article_27163_c74fe8f2d4199523dfb7c1e3cfe01589.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501THE GAS PRESSURE INFLUENCE ON COMBUSTION CHAMBER FLOW CHARACTERISTICS4794922716410.21608/asat.2011.27164ENOlaRashedAssistant Professor, Aerospace Department, Cairo University.Journal Article20190214The atomization process influences combustion. The Sauter Mean Diameter (SMD), the pressure, and the temperature of the combustor play an important role in the progress of the combustion. The objective of this study is to develop a mathematical model to evaluate the effect of the gas pressure on the combustion chamber flow characteristics. Based on this model a computer program has been designed taking into account the effects of droplet internal circulation, change in combustion chamber gas temperature, the non-unitary Lewis number, the changing gas film thickness surrounding the droplet, the slip, the variable thermo-physical properties. The effect of gas pressure on Liquid Reynolds number, gas Reynolds number, non-dimensional radii, Lewis number, droplet velocity and droplet surface temperature is established. Increasing the gas pressure increases the vapor mass fraction, which affects all other parameters (thermal conductivity, diffusivity, specific heat of liquid and gas, mass and heat transfer number) and leads to a decrease in combustion time. The droplet surface is found to reach its maximum temperature in a shorter time if the pressure is higher. By increasing the gas pressure the droplet-evaporating rate increases, which leads to a decrease in evaporating time. Consequently the combustion chamber volume is decreased. Iterations on the chamber dimensions are done until the program converges.https://asat.journals.ekb.eg/article_27164_b91871eac6e96a7ef291f2d97800782c.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501THEORETICAL INVESTIGATION OF AN ADIABATIC CAPILLARY TUBE WORKING WITH PROPANE / n-BUTANE / iso-BUTANE BLENDS4935122716610.21608/asat.2011.27166ENM.FatouhAssoc. Professor, Dpt. of Mechanical Power Engineering , Faculty of Engineering at El-Mattaria (Helwan University), Masaken El-Helmia P. 0., Cairo 11718, Egypt.Journal Article20190214In this paper, a theoretical model is developed to predict refrigerant flow characteristics in adiabatic capillary tubes using propane/n-butane/iso-butane mixtures as working fluids in a domestic refigerator. This model is based on mass, energy and momentum conservation equations for a homogeneous refrigerant flow under different inlet conditions such as subcooled, saturated and two-phase flow. Effects of inlet pressure (8-16bar), inlet vapor quality (0.001-15%), inlet subcooling degree (1-15°C), mass flow rate (1-5 kg/h), propane mass fraction (0.5-0.7), capillary tube inner diameter (0.6-1.0mm) and tube surface roughness on the capillary tube length are predicted. Results showed that the present model predicts data that are very close to the available experimental data in literature with an average error of 2.65%. Pressure of hydrocabon mixture (HCM) decreases while its vapor quality, specific volume and Mach number increase along the capillary tube. Also, the results indicated that capillary tube length is largely dependent on capillary tube diameter. Other parameters such as mass flow rate, inlet pressure, sub-cooling degree (or quality) and relative roughness influence the capillary tube length in that order. Capillay tube length as function of the significant parameters is presented in equation form. Also, capillary tube selection charts either to predict mass flow rates of propane/n-butane/iso-butane mixtures through adiabatic capillary tubes or to select the capillry tube size according to the required applications are developed. The comparison betweenn R12, R134a and the hydrocarbon mixture (HCM) of propane/n-butane/iso-butane indicated that for a given mass flow rate, the pressure drop per unit length is about 4.13, 5.0 and 12.0 bar/m for R12, R134a and HCM, respectively. The ratios of average mass flow rate of HCM with propane mass fraction of 0.6 to those of R12 and R134a are about 0.62 and 0.67, respectively. Average capillary tube length for HCM with propane mass fraction of 0.6 is longer than those of R134a and R12 by about 30% and 48%, respectively.https://asat.journals.ekb.eg/article_27166_d7a9165eed88a3d2223a0bce4da8bb6c.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501ASSESSMENT OF PROPANE/COMMERCIAL BUTANE MIXTURES AS POSSIBLE ALTERNATIVES TO R134a IN DOMESTIC REFRIGERATORS5135282716710.21608/asat.2011.27167ENM.FatouhAssoc. Professor, Dpt. of Mechanical Power Engineering , Faculty of Engineering at El-Mattaria (Helwan University), Masaken El-Helmia P. O., Cairo 11718, Egypt.M.El KafafyGraduate student, Dpt. of Mechanical Power Engineering , Faculty of Engineering at El-Mattaria (Helwan University).Journal Article20190214The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. Performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures (-35 to -10°C) and condensation temperatures (40 to 60°C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/n-butane mixture with various propane mass fractions. Performance characteristics of the considered domestic refrigerator was identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to the compressor, discharge temperature, pressure ratio and the refrigerant mass flow rate. Results showed that pure propane could not be used as a drop-in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desrirable characteristics, but requires compressor change. Coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fraction from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that average refrigerant mass flow rate of propoane/commercial butane mixture is 50% lqwer than that of R134a. Also, results indicated that R134a and propoane/commercial butane mixture of 60% propane mass concentration have approximately the same values of saturation pressure, compressor discharge temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/n-butane mixture with 60% propane is the best drop-in replacement for R134a in domestic refrigerators under normal, subtropical and tropical operating conditions.https://asat.journals.ekb.eg/article_27167_eedcbbb769bd5a5836bc2259284a6793.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Simulation of Satellite Heat Pipe Radiator5295522716810.21608/asat.2011.27168ENAhmedFathyGraduate student, DpL Of Meth. Power. Military Technical College, Cairo, Egypt.MohamedAfifyLecturer, Dpt. Of Mech. Power, Military Technical College, Cairo, Egypt.KaramEl-ShazlyProfessor, Opt. Of Mech. Power, Shoubra Faculty of Engineering - Zagazlg University, Cairo, Egypt.Journal Article20190214Heat pipes are widely used in the thermal control system of satellites. A coolant fluid, being pumped through a header, collects heat from the satellite components and transfer it to the radiator heat pipes. The object of this work is to obtain relationships among the heat load of radiator, the mass flow rate of coolant fluid and the main dimensions of the radiator, in order to satisfy the temperature ranges necessary for the operation of satellite components. A mathematical model was used to simulate a heat pipe radiator. Karam's data [5] has bean used to verify the validity of the program, with header length of 8 m, radiator height of 3.16 m, evaporator length of 0.15 m, number of heat pipes of 53 and satellite load of 6250 W. The output result concerning the heat transport capability of the radiator, given by the simulation program, are identical to karam's analytical results. The program was used to study the effect of some parameters like the header length, the satellite heat load and the environmental load. Changing the header length from 2 m to 10 m, it has been seen that the output coolant temperature decreases as header length increases which improves the thermal control of satellite. Changing the satellite load from 3000 W to 10000 W, it has been seen that the heat transport per pipe increases as the satellite thermal load increases. The results also showed that increasing the environmental load could stop the radiator function and consequently it should be insulated from the surrounding to work property.https://asat.journals.ekb.eg/article_27168_995aef14e4afc7ef888c28109131f9a7.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501PERFORMANCE OF WICKLESS HEAT PIPE WORKING WITH R134a5535712716910.21608/asat.2011.27169ENAhmedFathyGraduate student, Dpt. Of Meth. Power. Military Technical College, Cairo, Egypt.MohamedAfifylecturer, Dpt. Of Mech. Power, Military Technical College, Cairo, Egypt.KaramEl-ShazlyProfessor Dpt. Of Mech. Power, Shoubra Faculty of Engineering — Zagazig University, Cairo, Egypt.Journal Article20190214One of the important use of heat pipes is the thermal control of satellites. The performance characteristic of a wickless copper heat pipe was investigating experimentally. For that aspect, a test rig was built up for a heat pipe with 1.4 m length, 18 mm internal diameter and 2 mm thickness charged with R134 a as working fluid with a temperature range from -40 °C to 110 °C. The evaporator section was electrically heated with heat flux varying from 200 to 600 kW/m2. The condenser section was water cooled by using an overflow tank. Thermocouples were embedded on outside surface along the length of the heat pipe, and this surface was thermally insulated. The heat pipe transient responses as well as the axial distribution of wall temperature were plotted, for the three sections of the heat pipe, at different values of heat flux. The overall thermal conductance and the heat transfer coefficients at the evaporator and the condenser sections were plotted against the heat flux. These values were compared with the results published in literatures. The effect of some parameters on the heat pipe performance had been studied like the tilt angle and the adiabatic length of the pipe. The results show that the increase of the tilt angle or the adiabatic length of the pipe reduces its heat transport capacity. The correlation of Sakr and Ramadan [ 8 ] for the entrainment limit of heat pipes, had different values of n for R11, R12, R22 and R118 as working fluids. Applying the present results in this correlation, it had been found that n= 4.056 for wickless heat pipe with R134a.https://asat.journals.ekb.eg/article_27169_92bbd060ba78f11e805e4696145dc628.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501THE EFFECT OF USING ARGON IN THE INTAKE CHARGE ON THE PERFORMANCE OF A DIESEL ENGINE UNDER SYNTHETIC ATMOSPHERE CONDITIONS5735962717010.21608/asat.2011.27170ENW. M.NESSIMEgyptian Armed Forces.M. H.KHOBEIZ.Egyptian Armed Forces.M. A.SHAHINModern Academy.Journal Article20190214During the recent decades there have been substantial researches aimed to produce non-nuclear power systems for use in restricted fresh air supplies which has been identified by both the naval and the civilian communities. One particular class of power plant which has attracted a great deal of attention is the Air Independent Propulsion (AIP) systems.<br />The simplest of AIP systems is the Closed Cycle Diesel Engine (CCDE). A CCDE works like a regular Diesel engine, except that it uses synthetic atmosphere for the combustion of diesel fuel. The present work is established with the overall objectives to determine the performance of diesel engine operating on non-air mixtures compared with the normal air, and the effect of Argon on the combustion of Diesel engine. The test-rig with a single cylinder diesel engine was erected to evaluate the performance of the closed cycle diesel engine with Nitrogen or Argon as an inert gas balancing with CO2 with different percentages and constant 21% 02 by volume at different loads and constant speed. A computer simulation technique using single-zone model was used to predict the steady state performance for both closed cycle and normally aspirated diesel engine. The validation model has been used as a predictive tool for the study of Nitro-diesel closed<br />cycles. The deteriorating performance of the diesel engine when increasing the percentage of CO2 in the synthetic atmosphere is determined. Also the beneficial effects of using argon instead of nitrogen are analyzed.https://asat.journals.ekb.eg/article_27170_46c9a95c321afa8501e4f14579f4bc40.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501STATISTICAL EVALUATION OF SURFACE ROUGHNESS IN ABRASIVE FLOW MACHINING PROCESS5976092717110.21608/asat.2011.27171ENA. M.KohailEgyptian Army Forces.M. A.MandyAin Shams University.T. M.AhmedEgyptian Army Forces.Journal Article20190214Abrasive flow machining (AFM) process is used in a wide range of applications to deburr, polish, radius edges, remove recast layers, and produce compressive residual stresses on the surface. The aim of the present work is to study the effects of the different process parameters, such as machining time, concentration and mesh size of abrasive, as well as media flow speed ... etc. on the produced surface roughness. A mathematical model to evaluate surface roughness has been presented using experimental design. This model is can be used for the prediction of the surface roughness. Comparisons between experimental and theoretical results are also presented.https://asat.journals.ekb.eg/article_27171_79a686e95962f0390f4f9c79aa4c2933.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EVALUATION OF INTERFACE CHARACTERISTICS FOR DIFFERENT JOINTS PRODUCED BY EXPLOSIVE WELDING6116332717210.21608/asat.2011.27172ENM. Abd ELGhanyFayedLecturer, MTC, Egyptian Armed forces.G. M.AbdoResearchers, Res. Center, Egyptian Armed forces.M. TolbaSallamProfessor, MTC Egyptian Armed forces.Journal Article20190214This study was conducted to evaluate the bonding ability and the interface characteristics for four different joints produced by explosive welding. Three joints were elaborated using copper-nickel alloy as base plate with either stainless steel, carbon steel and commercially pure aluminum as flyer plates. The fourth joint was of commercially pure aluminum as base plate and carbon steel as flyer plate. Different explosive ratios and stand-off distances were applied. Experimental results showed good bonding quality in all joints. By increasing explosive ratio, at small stand-off distance of 2mm, fiat bonding interface was transformed to a wavy bonding interface in all joints. The form regularity and amplitude of the obtained wavy interface depend on the type of welded materials. Increasing the stand-off distance also transforms the flat interface, obtained at the small explosive ratio R= 1.4, to a wavy interface, only when the flyer plate was of (FCC) structure. When carbon steel flyer plate of (BCC) structure was used, increasing the stand-off distance showed no major modifications on the interface morphology. It was found that hardness on both sides of the interface was increased due to the high plastic flow that occurs in these regions. This hardening effect was very pronounced in the joints having a flyer plate made of carbon steel with higher coefficient of strain hardening. EDS and WDS analysis showed that diffusion did not take place between the welded plats however, diffusion was observed only in local melting zones along the interface.https://asat.journals.ekb.eg/article_27172_f7b2b81e9809d2a738771895e637a1fb.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CHARACTERISTICS OF WATERJET CUTTING FOR THE OFFSHORE INDUSTRY6356492717310.21608/asat.2011.27173ENH. A.SenbelAssociate Professor, Ain Shams University, Faculty of Engineering, Design and Production Engineering Department, Cairo, Egypt.Journal Article20190214Waterjet machining harnesses the kinetic energy of a high velocity waterjet to cut materials. Waterjet cutting for the offshore industry has shown particular interest in recent years. Abrasive Waterjet (AWJ) is seen as an ideal cutting tool for cutting buoys and other structures away from the seabed. The study reported in this paper analyzes certain aspects associated with waterjet cutting in an attempt to improve it as a machining process and to investigate its suitability for offshore use. Specific factors looked at, were the effects of abrasive flow rate on AWJ machining, the performance of waterjet when used underwater, and nozzle design to try and improve the jet focus. From experimentation, cutting while submerged was observed to be possible, although the performance of the jet was slightly stunted due to the interaction of the surrounding fluid. As the nozzle was moved away from the workpiece, thereby increasing the standoff distance, the performance of the jet was found to deteriorate further. An increase in abrasive flow rate was found to aid cutting initially; however at higher flow rates the increase was found to have a detrimental effect on the jets cutting performance. Therefore an optimum abrasive flow rate was found to be between 4.4 g/s & 7.4 g/s. The slope angle of the nozzle axis has no significant effect. The effect of changing nozzle geometry was analysed by computational fluid dynamics. The outcome was that the change in geometry had no effect on the upstream flow.https://asat.journals.ekb.eg/article_27173_8931322614e1204c4277663264b51231.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501DIRECT- SEQUENCE SPREAD SPECTRUM WITH DIVERSITY RECEPTION IN A SHADOWED NAKAGAMI FADING LAND MOBILE SATELLITE CHANNEL6536662717410.21608/asat.2011.27174ENAbdel-Hamid G.M.Egyptian Armed Forces.Abdel-Aziz A.M.Egyptian Armed Forces.Journal Article20190214This paper is concerned with evaluating, the performance of a direct sequence spread-spectrum with two types of diversity copmbining techniques, namely, Selection diversity (SDC) and maximal ratio combining (MRC), in a land mobile satellite transmission system, using 16-ary Quadrature Amplitude modulation (16mYQAM). It is assumed that the channel consists of a Nakagami shadowed line-of-sight signal plus Rayleigh distributed multipath signals, as well as additive white Gaussian noise. Fading and shadowing cause both envelope and phase variations of the received signal. The paper derives upper bounds of the probability of error due to both of these variations, and closed form expressions are found for L branch diversity using both MRC and SDC in a realistic (practical) operating environments with independent but not identically distributed diversity paths. Assuming a Gaussian approximation for the interference, numerical results are obtained for both spread spectrum and spread spectrum with diversity eception in land mobile satellite communication systems with 16arYQAM for light and average shadowing and fadinghttps://asat.journals.ekb.eg/article_27174_ec6cbfb22b7b021b1640e80531057662.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501PERFORMANCE OF TURBO CODES WITH SPACE-TIME TRANSMIT DIVERSITY6676762717510.21608/asat.2011.27175ENSalah, M.M.Egyptian Armed Forces.EI-Agooz, S.S.Egyptian Armed Forces.Mahroos, A.I.Egyptian Armed Forces.Journal Article20190214In future wireless communication systems such as 3rd generation mobile systems, increasing the downlink capacity from the base stations to remote units becomes more important due to high data rate applications such as wireless internet access. Turbo Codes and Space-Time Transmit Diversity (STTD) are two of the most recently techniques to improve system performance and capacity. In this paper, the performance of turbo codes with transmit diversity is studied. The effect of number of transmits antennas, puncturing, and frame length are investigated over Rayleigh fading channels. The simulation results show that a significant gain is achieved when using turbo codes with space-time transmit diversity technique.https://asat.journals.ekb.eg/article_27175_83fd4c4404973be5f2dec2c88b48cd4e.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CODED THROUGHPUT AND DELAY PERFORMANCE ANALYSIS OF THE HYBRID SFH/DS OVER FADING CHANNEL6776892717610.21608/asat.2011.27176ENAbdel-Moneim M.FoudaEgyptian Armed Forces.EssamAbdel-WaneesEgyptian Armed Forces.AhmedEl-BaklyEgyptian Armed Forces.Journal Article20190214This paper presents the performance analysis of throughput and delay, when it is required to transmit data over a packet switched code division multiple access network based on the coded hybrid SFH/DS SSMA. The performance is discussed assuming noncoherent hybrid SFH/DS system which employ independent random direct sequences and random memoryless frequency hopping patterns, slotted ALOHA channel access protocols, and different types of Reed Solomon RS (n,k) forward error control (FEC) coding techniques including; Hamming code, BCH code, and Golay code. The system is operating through multipath fading channel, and uses deferentially phase shift keying DPSK modulation technique. Different performance measures other than the BER will be investigated, those are the system throughput and delay, a closed form expression for the hybrid system throughput and delay is derived for the system under consideration, they are presented and plotted when the system is operating over such fading channel and assuming different coding rate , as well as a comparison for the system performance considering different types of Reed Solomon RS (n,k) forward error control (FEC) coding techniques including; Hamming code (7,4), BCH code (15,7), and Golay code (23,12) are presented.https://asat.journals.ekb.eg/article_27176_ac62fed9a47f47ff56568fc58e754b03.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501OPTIMUM RECEPTION OVER IMPULSIVE NOISE CHANNELS6917012717710.21608/asat.2011.27177ENEl-barbary K.A.Egyptian Armed Forces.EL-Mandy A.E.Egyptian Armed Forces.EL Shawadfy S.A.Egyptian Armed Forces.Journal Article20190214The paper presents an optimum receiver for digitally modulated signals in additive class-A impulsive noise. The receiver is based on maximum likelihood (ML) approach. The performance of the receiver is derived theoretically. The performance is measured by the bit error probability. Computer simulations are illustrated to validate the theoretical developments. It is shown that the performance of the developed receiver is sensitive to the impulsive index of the noise. Decreasing the value of the impulsive index degrades the performance of the receiver and reduces the receiver resistivity against frequency offset.https://asat.journals.ekb.eg/article_27177_e73e3e30559789a2b8a524de4b5b4a30.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A SEGMENTED MATCHED FILTER FOR PN CODE ACQUISITION7037162717910.21608/asat.2011.27179ENSalahEl-AgoozChair of Communication, Military Technical Collage.Alaa El-DinRohiemChair of Communication, Military Technical Collage.MohammedEI-SakaTechnical Research Center.Journal Article20190214This paper presents a segmented matched filter (SMF) for PN code acquisition in direct sequence spread spectrum systems. While conventional matched filters provide fast acquisition in the presence of high co-user interference, they are unable to handle the problem of Doppler shift. This problem is alleviated by filter segmentation with non-coherent summation. The paper focused on validating the segmented matched filter codephase synchronization method. Simulations were carried out to verify the functionality of the SMF from a statistical point of view. The simulated performance of the SMF was compared with that of the traditional synchronization techniques and was found to show an improvement over the traditional methods when Doppler shift was present.https://asat.journals.ekb.eg/article_27179_3de2ff1cc9d30b89257051e7e484b74b.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501AN EMBEDDING ALGORITHM FOR DATA HIDING7177242718010.21608/asat.2011.27180ENAlaaFahmyAssoc. Prof. Dept. of Electrical Engineering, Military Technical College, Cairo, Egypt.Journal Article20190214Data hiding is frequently termed steganography, which is very close to cryptography. The purpose of cryptography is to make messages unintelligible so that only the intended receiver who posses the secret keys can recover the messages. Sometimes, it may be desirable to achieve security and privacy by masking the messages instead of encrypting it. This problem is addressed by steganography, which has.been used in spy applications. If Alice (spy in a foreign country) wants to send messages abroad, she will use a local communication channels. On the assumption that the communication channel is monitored all the time hence, sending an encrypted messages would raise suspicion in her. Therefore, Alice would prefer to use steganographic technique rather than a cryptographic one. An embedding algorithm, based on elliptic curve has been presented to provide both data encryption and data hiding in digital images.https://asat.journals.ekb.eg/article_27180_90b2bc7088e693bb8f7aad9e9a969e95.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501NEW PROPOSAL FOR KEY MANAGEMENT7257302718110.21608/asat.2011.27181ENAlaaFahmyAssoc. Prof. Dept. of Electrical Engineering, Military Technical College, Cairo, Egypt.Journal Article20190214Key management represents a major and the most sensitive part of cryptographic systems. It includes key generation, key distribution, key storage, and key deletion. It is also considered the hardest part of cryptography. Designing secure cryptographic algorithms is hard, and keeping the keys secret is much harder. Cryptanalysts usually attack both symmetric and public key cryptosystems through their key management. We introduce a protocol to exchange cipher keys over insecure communication channel. This protocol is based on public key cryptosystem, especially elliptic curve cryptosystem. Meanwhile, it tests the cipher keys and selects only the good keys and rejects the weak one.https://asat.journals.ekb.eg/article_27181_bf7f952bea8b33eec4604c67d6e7127a.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CONSTELLATION SHAPE AS A ROBUST SIGNATURE FOR DIGITAL MOULATION RECOGNITION7317452718210.21608/asat.2011.27182ENKhairy A.El-BarbaryDepartment of Electronic Warfare Engineering, Military Technical College, Cairo, Egypt.Elsaid Elsaid A.AzouzCommunication Ministry , Frequency Management Center , Cairo, Egypt.Ashraf A.MamdohDepartment of Electronic Warfare Engineering, Military Technical College, Cairo, Egypt.Mohammed A.Abou El-AzmDepartment of Electronic Warfare Engineering, Military Technical College, Cairo, Egypt.Journal Article20190214Modulation recognition plays a key role in analysis of the intercepted signals by electronic warfare receivers. A hybrid approach for modulation recognition is introducd. This approach consists of two main classification and decision algorithms. The first is a pattern recognition algorithm for reconstruction of the constellation shape as a stable modulation signature of the intercepted signal. The second is a threshold detection logic algorithm for identification of the modulation type of the intercepted signal. These two algorithms are connected through a feature extraction procedure The complex envelope, which represents both the in phase and quadrature phase components of the received signal after carrier estimation [1,2,11] is utilized as the input of the pattern recognition algorithm. The proposed algorithm shows a robust behavior for identification of single tone digital modulated signals for a relatively low signal to noise ratio (SNR) compared with the ordinary modulation recognition algorithms. Experimental results are shown for various modulation standards including M-ASK, M-PSK, and M-QAM only for M= 8 or 16, received through an AWGN channel and in the presence of carrier recovery errors.https://asat.journals.ekb.eg/article_27182_4f58c860445d0438aab5af5b0475b2f3.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CHAOTIC CRYPTOSYSTEM USING THE AES ENCRYPTION ALGORITHM AS ENCRYPTION AND DECRYPTION RULE7477562718310.21608/asat.2011.27183ENShehata A.R.Egyptian Armed Forces.Elagooz S.S.Egyptian Armed Forces.Dahshan H.M.Egyptian Armed Forces.Journal Article20190214Chaos and cryptography have some common features, such as sensitivity to variables and parameters change. Many fundamental characteristics of chaos, such as the ergodicity and mixing property and the sensitivity to initial conditions can be connected with the "confusion" and "diffusion" property in cryptography. A combination between cryptosystems realized in analog circuits and conventional cipher has been made by using the AES as the encryption and decryption rule in the chaotic cryptosystem based on chaos synchronization techniques. The proposed algorithm has been simulated and applied in encrypting and decrypting images. The results show that encrypted data have passed all statistical tests and the confusion and diffusion properties have also been demonstrated by testing the histograms of the ciphered images and calculating the amount of correlations between the adjacent pixels in the ciphered image.https://asat.journals.ekb.eg/article_27183_b91293f5f2e1fc19fe945999f987aa6b.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EFFECT OF IMPERFECT POWER CONTROL ON PARALLEL INTERFERENCE CANCELLATION FOR CDMA7577672718410.21608/asat.2011.27184ENYahyaMohassebEgyptian Armed Forces.HishamElgamalPort Said Faculty of Engineering, Suez Canal University.Journal Article20190214This paper presents a study of the effect of imperfect power control on the performance of a Partial Parallel Interference Cancellation (PPIC) multiuser receiver. We show that the PPIC receiver can absorb the effect of imperfect power control to a great extent compared with other types of receivers. Additionally, the effect of imperfect power control on the optimum weights of the PPIC receiver is considered. It is found that imperfect power control causes the receiver to become more susceptible to performance degradation as a result of deviation from optimal weights.https://asat.journals.ekb.eg/article_27184_ffd9a0f6818e9ebc36fff856a5089422.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Performance Improvement of CDMA IRIDIUM Satellite Systems7717802718610.21608/asat.2011.27186ENSHERIEF SANIYEMAMPhD., Egyptian Armed Forces.Journal Article20190214Applying different coding techniques to the Gaussian mixture traffic model. The effect of convolutional and Turbo coding on the probability of error and the capacity are investigated for CDMA IRIDIUM Low Earth Orbit Satellite (LEOS) systems. The model employed assumes a contaminated Gaussian traffic model. The conventional Gaussian distribution can be considered as a special case. The probability of error decreases using convolutional and turbo coding respectively. Furthermore, the capacity increases. Slight varitions around these values are obtained depending on the traffic nonuniformity. Thus Turbo coding improves the performance of the CDMA LEOS systems to a great extend.https://asat.journals.ekb.eg/article_27186_d723bebbec88c6c9af024c8d0a5bc5f7.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A RELIABILITY MEASURE FOR ESM SYSTEM DEINTERLEAVERS7818012718810.21608/asat.2011.27188ENHossam E. Abou-BakrHassanDr., Egyptian Armed Forces.Journal Article20190214An Electronic Support Measures (ESM) system consists principally of a passive radar receiver and a deinterleaver. It measures the monopulse parameters of intercepted radars, sorts them into individual radars, identifies those radars, and passes their identities to an Electronic Counter Measures (ECM) system for further action. When the pulse arrival rate is too high for an ESM system, it will skip some pulses and consequently the reliability of radar identification will be decreased. From queueing theory, this paper develops an expression that relates the reliability, quantified as a figure of merit called the factor of successful processing (F,), to the pulse arrival rate and the service times of the ESM system. An on-line method to measure F., is also given, which shows that the measurements are in close agreement with the theoretical values.https://asat.journals.ekb.eg/article_27188_b586d39d80bc8bbe2ff82c5c606c158a.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Optimal Antenna Tracking for LEO-GEO Cross-Link8038242718910.21608/asat.2011.27189ENE. A.SolietProf., Military Technical college, Cairo, Egypt.M. A.SolimanPh.D., Zaqaziq University, Shargia, Egypt.Karim A.FouadEng., Air force R&D Department , EAF.Journal Article20190214This paper presents a proposal for an attitude control system for Low Earth Orbit (LEO) satellite antenna that keeps tracking of an existing geo-stationary (GEO) communication satellite as a data relay satellite. The proposed scheme can increase the communication availability with a remote sensing LEO satellite. Moreover, the proposed system improves both the communication coverage area of the LEO satellite and its scanning availability in the real time. This improvement is a real need in the remote sensing application. The use of cross-link in data relay systems requires accurate control system in order to enable tracking the data relay satellite (GEO satellite). The proposed system permits the data relay system to work properly and efficiently. The proposed data relay system provides the real time data accessing, data integrity, and wider coverage area than the obtained one from typical LEO-ground station scheme.https://asat.journals.ekb.eg/article_27189_834ae24caf8f923105867f65f26cf2dd.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501REAL TIME ADAPTIVE VARIABLE DIMENSION KALMAN FILTER IN MANOEUVRING TARGET TRACKING8278362719110.21608/asat.2011.27191ENSemi. S.S.Dr.Prof., Asad academy For Military Engineering, Aleppo, Syria.Jamil. M.S.Assistant Prof., Asad academy For Military Engineering, Aleppo, Syria.Journal Article20190214Tracking process for manoeuvring targets is still the main problem in Kalman filtering [1-6]. The conventional variable dimension filter used for manoeuvring target tracking is not a practical filter because of the previous state vector estimates for several scans must be recomputed to avoid the filter divergence when a new target model is detected [1,3-5]. In this paper a real time adaptive variable dimension filter is proposed. This proposed filter is without the previous estimates to be recomputed. This proposed filter is also with a less filter divergence level and therefore more practical filter. Such a filter will be more appropriate to use when the target rather rarely experiences a new models. When the target more frequently experiences a new models it will be better to use the constant acceleration filter. This constant acceleration filter is actually a part of the proposed filter in this paper. This constant acceleration filter is also capable of<br />operating in real time with no filter divergence at the expense of slight increasing of the estimate error variance level.https://asat.journals.ekb.eg/article_27191_0fca277c8963dc12cfd124c9c7760f70.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Adaptive Control of Brushless DC Motor Using Neural Network Identification and Pole Shifting Controller8378452719210.21608/asat.2011.27192ENA.EliwaEgyptian Armed Forces.W.SabryEgyptian Armed Forces.A.El-WakeelEgyptian Armed Forces.U.Abou-ZayedEgyptian Armed Forces.Journal Article20190214In this paper adaptive control of a brushless DC motor (BLDCM) using neural network identification and pole shifting (PS) controller is presented. Proper system identification is one of the important factors that gives a good controller performance. This means that when the model parameter estimates are good, the controller output is good, whereas if the model parameter estimates are bad then almost surely the computed control will be bad. Proper selection of the identified system model order is also investigated. A comparison study between fuzzy logic controller and the proposed controller is also investigated.https://asat.journals.ekb.eg/article_27192_6fabf67d24e6e00c68a48bfa1d4a02b8.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A laboratory Realization of Control Systems of Capacitor Self-Excited Induction Generator8478572719310.21608/asat.2011.27193ENF. A.KhalifaEgyptian Armed Forces.A.EliwaEgyptian Armed Forces.W.SabryEgyptian Armed Forces.M. E. A.RahmanEgyptian Armed Forces.Journal Article20190214This paper presents a laboratory set-up simulation of the wind energy power system including capacitor self-excited induction generator (CSEIG). An implementation of PI, PID and Fuzzy Logic (FLC) Controllers is developed. The hardware components and circuits are also designed and realized. The influence of these control techniques on the performance characteristics of the system under consideration is examined. The obtained experimental results show that the transient response and damping perform-ance with FLC is better than that of PI and PD controllers.https://asat.journals.ekb.eg/article_27193_299cb37dc117d71e0857d583a99e77b9.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501ESTIMATION OF SENSORS RELIABILITIES USING NEURAL NETWORK AND FUZZY TECHNOLOGIES8598692719410.21608/asat.2011.27194ENAshraf Mamdouh A.AzizMohamed Hassan A.AzeemJournal Article20190214The sensors reliabilities in multisensor distributed decision systems with data fusion are the a priori statistical data needed to optimize the system it terms of higher detection probability. This paper proposes a new approach in data fusion systems to estimate the sensors reliabilities and to improve the system performance. The proposed approach is based on neural network and fuzzy logic technologies. Use of neural networks to learn system behavior seems to be a good way to solve the problem of the needed a priori statistical data in multisensor distributed detection systems with data fusion. Also, fuzzy logic has been proven very successful in solving problems in many areas where conventional model is either very difficult or inefficient/costly to implement. Use of fuzzy logic in multisensor distributed detection systems to determine uncertainty or confidence value (grade of membership function) for each hypothesis has the advantages of the soft decision approach. Combining the two technologies in multisensor distributed detection systems provides the benefits of both technologies. Thus using neural network and fuzzy logic technologies reduces the needed statistical data and improves system performance. The proposed approach does not require a priori statistical knowledge of the sensing process. The optimum fusion rule using the proposed approach is derived. The performance of the proposed approach is evaluated and compared to the performance of the hard-decision approach. The proposed approach provides detection probability improvement over a comparable hard-decision system and is able to correctly estimate the sensors reliabilities.https://asat.journals.ekb.eg/article_27194_574d6c710c4298d474e6aa66de3fa787.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501AUTONOMOUS UAV FUZZY LOGIC NAVIGATION AND OBSTACLE AVOIDANCE CONTROLLER8718842719510.21608/asat.2011.27195ENAMR A.H.Egyptian Armed Forces.SERAG E.D.H.Electronic and Communication Department, Faculty of engineering. Cairo University.MOHAMEDH.Egyptian Armed Forces.Journal Article20190214Unmanned Aerial Vehicles (UAVs) are defined by the United States Department of Defense (DOD) as powered, aerial vehicles that do not carry a human operator. UAVs control systems have assumed an increasingly important role in the development and advancement of modern civilization and technology. In recent years, intelligent control of autonomous navigation of UAVs has gained much interest mainly: neural networks, non-linear adaptive control, fuzzy logic as well as combinations of these methods, such as, neuro—fuzzy control, or fuzzy logic and evolutionary or genetic algorithms. The purpose of this paper is to develop an autonomous UAV fuzzy Logic navigation and obstacle avoidance controller that is capable to perform a way point navigation and obstacles avoidance along its flight. The navigation and obstacle avoidance behavior is transformed via fuzzy rules. Multi-platform simulation package is developed to perform closed loop on-line environment sensing. Several simulation tests have been conducted on the new controller. These tests show that the proposed controller achieves the desired performance with respect to its sensors capability and limitations.https://asat.journals.ekb.eg/article_27195_9dbcea07cdf245a3ee13c7b5f09d1177.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501PERFORMANCE EVALUATION OF FREQUENCY AGILE RADAR IN PRESENCE OF CHIRP JAMMING8858942719610.21608/asat.2011.27196ENEl-Mandy, A.E.Egyptian Armed Forces.ABD EL-latif MohamedS.Egyptian Armed Forces.EL Gamel S.A.Egyptian Armed Forces.Journal Article20190214This paper studies the performance of frequency agile radar (FAR) under the effect of chirp jamming technique. Also, the improvement in the barrage jammer range when using the chirp jamming technique is studied. The considered radar is assumed to be a search radar, and the jammer is stand off jammer. A simple simulation model is used to generate the jamming signal in both time and frequency domain. This model is applied to simulate both chirp jamming and barrage jamming signals. The effect of the proposed chirp jamming on the detecting range of FAR is studied. Moreover, the comparison between the effect of barrage jamming and chirp jamming techniques on the jammer effective range and on the FAR detection range is studied.https://asat.journals.ekb.eg/article_27196_4e9a4d089822a1e979de4c4516028cc2.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Assessment of Earth Remote Sensing Microsatellite Power Subsystem Capability during Detumbling and Nominal Modes8959082719710.21608/asat.2011.27197ENM.ZahranNational Authority for Remote Sensing and Space Science, Cairo Egypt.+Electronics Research Institute, NRC Blg., El-Tahrir St., Dokki, 12311-Giza,
EGYPT, Tel./Fax. 00202(3310512/3351631).M.OkashaNational Authority for Remote Sensing and Space Science, Cairo Egypt.Galina A.IvanovaYuzhnoye State Design Office, 3, Kryvorozhzkaya st., Dniepropetrovsk, Ukraine, 49008,Fax 38(056)770-04-30.Journal Article20190214The Electric Power Subsystem (EPS) is one of the most critical system on any satellite because nearly every other subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to do that withstanding the radiation, thermal cycling, and vacuum of a hostile space environment as well as the subsystem degradation over the time [1]. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit RI After the satellite separates from the launch vehicle (LV) to its orbit, in almost situations, all the satellite subsystems (attitude determination and control, communication, and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) beside the consumed power in EPS management device. But at this point (separation point, detumbling mode), the satellite angular motion is high and the orientation of solar arrays with respect to the sun will change in a non-uniform way, so the amount of power generated by solar arrays will be affected. The objective of this research is to select the satellite EPS components, types; estimation the solar arrays illumination parameters and determination of the efficiency of solar arrays during both detumbling and nominal modes.https://asat.journals.ekb.eg/article_27197_614a5d38ac74d7f8c7205f5892e656fc.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A NEW APPROACH FOR MOVING TARGET DETECTION USING BARTLETT METHOD FOR SPECTRAL ESTIMATION9099242719810.21608/asat.2011.27198ENAbdel Rahman H.ElbardawinyEgyptian Armed Forces.Khairy A.ElbarbaryEgyptian Armed Forces.Fathy M.AhmedEgyptian Armed Forces.Journal Article20190214Moving Target Detection (MTD) is an automated radar signal and data processing system, which is designed to improve the performance of radar systems in the presence of various forms of clutter. Consequently, it provides high probability of detection (Pd) for an acceptable probability of false alarm (Pia). It employs coherent, linear Doppler filtering, adaptive thresholding and a fine ground clutter map to reject ground clutter, rain clutter, birds, and interference. The current MTDs relay on the Fast Fourier Transform (FFT) of the total received data sequence to estimate the clutter power spectrum and consequently reduce or remove its effect on the detection performance. Direct FFT leads to high sidelobes level and requires a significant large computation time. The high level sidelobes increases the false alarm probability at the output of the Doppler filters bank. A solution for reducing the effect of spectral sidelobes is the utilization of window functions. However, this solution leads to widening the main spectral lobe and reduce the Doppler resolution. Also it increases the hardware complexity of the system. In the present work, Bartlett method for spectral estimation which depends on dividing the received data sequence into a number, K, of nonoverlapping segments and averaging the calculated FFT for each segment over K, is applied in the MTD instead of the direct FFT for typical ground based radar. The proposed method enhances the target detection capabilities, by providing higher detection probabilities, lower false alarm rates and an additional gain of 7-10 dB in the improvement factor, in the presence of ground and weather clutter, compared to the traditional one. This is because the sidelobe levels obtained are very small in magnitude. This in turns facilitates the realization of the Doppler filters bank without using additional weighting. The obtained performance can be achieved by applying the direct FFT with weighting function to the total received data sequence, which leads to a more hardware complexity and long time calculations compared to the proposed method. Computer simulation results are presented to support the superiority of the proposed technique.https://asat.journals.ekb.eg/article_27198_3c16f1d536284b0f2406c7e6f045a724.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501EFFICIENT FPGA ARCHITECTURE OF GREY-SCALE SOFT MORPHOLOGICAL FILTERS FOR IMAGE AND VIDEO RESTORATION9259352719910.21608/asat.2011.27199ENHamid M.S.Egyptian Armed Forces.Ragab A.S.Egyptian Armed Forces.Journal Article20190214Recently, Soft Morphological Filters have shown excellent performance in restoring noisy images. To add soft morphological filters in image processing chains and also to process image sequences in real time, it became a necessity to implement soft morphological operations in hardware. In this paper, FPGA architecture of grey-scale soft morphological filters is proposed. The architecture is based on a stack filter expression with some modification. The design can calculate soft morphological operations of greyscale soft morphological filters with structuring functions of any size and shape inside the structuring function's overall support. The filter architecture guarantees fixed processing time independent of the size and shape of the structuring function of the filter. Implementation results showed that the proposed filter architecture is suitable for real time applications.https://asat.journals.ekb.eg/article_27199_7d448cdd14f8155de274d3a1a8e1ab0c.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501Investigation of On-Board Compression techniques for Remote Sensing Satellite Imagery9379462720310.21608/asat.2011.27203ENFawzy ELtothamyHassanPh.D., Egyptian Armed Forces.Gouda IsmailSalamaPh.D., Egyptian Armed Forces.Mohammed SharawyIbrahimprof. Dr., Egyptian Armed Forces.Ramy MohammedBahyB.Sc., Egyptian Armed Forces.Journal Article20190214The transmission of image data acquired by remote sensing missions, based on space borne platforms is a major bottleneck, as a result of the limitation of on-board power, the huge volume of transmitted data, and the number of accessible ground receiving stations. In particular these arguments hold true for small satellites that faces additional design constraints in terms of size, mass and cost .To overcome downlink restriction, image compression has to be applied, although the provided data transmission rates are constantly growing, they can't keep up with the exponentially increasing data flood provided by the scanners, the reasons are twofold: First the acquisition rate exceeds the transmission rate. Second the satellite is not in constant visibility of ground receiving station, which effectively limits the downlinkable data volume per orbit. This paper introduces implementation of some of the compression techniques for both lossy and lossless which are used for the On-Board satellite missions, taking into consideration that the introduced compression method should support and enable the real time imaging and transmission. Also, a comparison study between both techniques is introduced based on measures like Compression Ratio (CR), Root Mean Square Error (RMSE) and Peak Signal-to-Noise Ratio (PSNR).The experimental results showed that: Huffman code is the most suitable code for lossless compression technique for satellite images, since it gives a considerable high compression ratio with respect to the other lossless algorithms (Run-Length Encode, Lempel-Ziv-Welch code and Arithmetic code). Huffman code does not require much storage capacity such as LZW or more computational requirements such as arithmetic code. Also, the most suitable lossy compression techniques for satellite images is applying Discrete Wavelet Transform (DWT) on the four Most Significant Bit Planes (MSPB) of the image then applying the arithmetic code over the resultant DWT coefficients. This technique achieves higher average compression ratio (8.28:1) than the two other techniques and at the same time the image quality is accepted.https://asat.journals.ekb.eg/article_27203_c53c9372dcff94f5b571de67f73245da.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501AN IMPLEMENTATION OF THE RUN-LENGTH ENCODE ALGORITHM USING FPGA9479542720810.21608/asat.2011.27208ENGouda I.SalamaEgyptian Armed Forces.Fawzy ELtohamyHassanEgyptian Armed Forces.M.SharrawyFaculty of Computers and Information, Helwan University, Egypt.Ramy M.BahyEgyptian Armed Forces.Journal Article20190214This paper presents a real time implementation of Run-Length Encode (RLE) using FPGA as one of image compression algorithms. The RLE algorithm can be implemented either on commercial DSP or as an ASIC but due to the huge development in the FPGA field, it is recommended to use the FPGA technology. The design steps from design entry to files which are needed for the download process are developed.https://asat.journals.ekb.eg/article_27208_f3a1d970ec7616d3a4b2579fe3404bc2.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501SECURE INTRANET USING VIRTUAL PRIVATE NETWORKS9559692720910.21608/asat.2011.27209ENIsmail A.IsmailAssociate Professor, Military Technical Collage, Cairo, Egypt.Moatasem M.Abd AllahDr., Military Technical Collage, Cairo, Egypt.Gamal A.OsmanDr., Technical Research Department, Cairo, Egypt.Tamer M.Abo NeamaEngineer, Technical Research Department, Cairo, Egypt.Journal Article20190214The network security concepts are targeting to prevent or reduce the risk of different types of network threats, especially during the transfer of secured data among the network nodes. Many security mechanisms are needed to achieve the network security goals. One of the important concepts for securing the transmitted data among open networks is Virtual Private Network (VPN). Some organizations don't trust on VPN security because it depends on commercial security products based on public encryption algorithms. For this reason, the objective is to make the VPN more trusted. The presented model aimed to add another layer of security to VPN security which satisfies the privacy, confidentiality, integrity and access control needs by implementing kernel-mode network driver. The implemented driver can be used to intercept the data buffers of the transferred network packets and encrypts its payload by using proprietary encryption algorithms.https://asat.journals.ekb.eg/article_27209_38c1603521a702fc934df10e0b0e09d7.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A NOVEL PRIVACY PRESERVING DATA MINING ALGORITHM9719882721010.21608/asat.2011.27210ENFahmy A.Aly(Prof.) Dean of Faculty of Computers and information, Cairo University.Fakhry M.Medhat(Ass. Prof.) College of Engineering and Technology Arabic Academy for Science, Technology and Maritime Transport (AAST).M. IsmailHanafy(Ph.D.) Egyption Armed Forces.EI-Zeweidy M.Aly(Eng.) Egyption Armed Forces.Journal Article20190214In recent years, there have been privacy concerns over the increase of gathering personal data by various institutions and merchants over the Internet. There has been increasing interest in the problem of building accurate data mining models over aggregate data while protecting privacy at the level of individual records. One approach for this problem is to randomize the values in individual records, and only disclose the randomized values. This method is able to retain privacy while accessing the information implicit in the original attributes. The distribution of the original data set is important and estimating it is one of the goals of the data mining algorithms. In this paper, a novel privacy preserving data mining algorithm based on the use of Artificial Neural Network (ANN) is introduced. The ANN model is based on single layer neural network (adaptive linear neuron network (ADALINE)), and it is used to reconstruct the original distribution. The paper also introduces a comparative study with two of the most recent algorithms that handled this issue. Our empirical results show that the new algorithm can reconstruct the original data distribution with a very high degree of precision.https://asat.journals.ekb.eg/article_27210_0069254af85806d9a88d3dfa577c1665.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501A NEW SINGLE TEST PATTERN GENERATOR FOR PSEUDOEXHAUSTIVE TESTING98910022721110.21608/asat.2011.27211ENMohamed H.EI-MahlawyEgyptian Armed Forces.WinstonWallerSenior Lecturer, VLSI group, Kent University at Canterbury.Journal Article20190214In this paper, we present a novel test pattern generator for pseudoexhaustive testing. This generator bridges the gap between convolved LFSR/SR and permuted LFSR/SR. It is considered to be the optimal pseudoexhaustive test pattern generator as far as the lengths of test set and hardware overhead are concerning. We present an efficient search to assign the residues for the inputs of the CUT to increase the chance to get several solutions and reduce the hardware overhead. With small number of permutations in the assigned residues, the chance of obtaining efficient results may be increased. The novel generator is considered the general form of the pseudoexhaustive test pattern generator. The simple LFSR/ SR, the permuted LFSR/SR, and convolved LFSR/SR are considered the special case of the novel generator. The experimental results indicate the superiority of this generator and the efficiency of our approach.https://asat.journals.ekb.eg/article_27211_8c309dc3c1e50614c9d4317572de4e6e.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501NEW TECHNIQUE FOR SIMULATION OF FREQUENCY SELECTIVE SURFACES ( FSS )100310102721210.21608/asat.2011.27212ENM. H.Abdel-AzeemHossamHamzaAhmadFawzyJournal Article20190214Two dimensional periodic arrays of patch elements can be used as frequency selective surfaces (FSS) owing to the frequency filtering properties of these structures. Arrays of square loops are of interest as frequency selective surfaces for dichroic reflector antennas. This paper describes a new way for modelling and analysis such FSS using the 3D Transmission Line Matrix method and compares the transmission characteristics predicted by the TLM method with those obtained experimentally.https://asat.journals.ekb.eg/article_27212_31206dd23c36e125aed72960aa4810a4.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501SECURE STORAGE FOR VOICE, IMAGE AND TEXT DATA USING STEGANOGRAPHY PARADIGM101110222721310.21608/asat.2011.27213ENMahmoud E.GadallahProf. Dr., Armed Forces.Abbass. S.AbbessDepartment of Computer Science, Modern Academy in Maadi.Journal Article20190214In this paper, an algorithm for data hiding is introduced. The purpose of this work is to secure the storage of information such as voice, images and text. Also, this technique has been tested to hide a mixture of text with images. The proposed algorithm is based on using the wavelet transform with post processing to increase the complexity of the hiding. The hiding algorithm reported in this paper has shown promising results from the point of view of the embedding capacity and the quality of the cover data (speech or images) as well as the quality of the recovered data.https://asat.journals.ekb.eg/article_27213_4bfba0d29c9fb43e2d3a5a7a6195ce5f.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501NUMERICAL STUDY OF Cr4+:YAG PASSIVELY Q-SWITCHED Nd:GdVO4 LASER102310322721510.21608/asat.2011.27215ENA.El-NozahyNational Institute of Laser Enhanced Sciences, Cairo Univ., Giza, Egypt.I. M.AzzouzNational Institute of Laser Enhanced Sciences, Cairo Univ., Giza, Egypt.Journal Article20190214Theoretical investigation is presented to analyze and optimize the performance of passively Q-switched Nd:GdVO4 laser with Cr4.:YAG as a solid state saturable absorber. A simple model is developed based on numerically solving the passive Q-switching rate equations, where the impact of the saturable absorber excited states photon absorption is included. The effect of both the saturable absorber doping concentration and output coupler reflectivity on the output laser characteristics are studied. The simulation results show reasonable agreement with those obtained experimentally by other research groups.https://asat.journals.ekb.eg/article_27215_9c7ce003c70cc1d5be21807e59a8498e.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501CHARACTERISTICS OF SEMI-CONDUCTOR LASER WITH EXTERNAL FEEDBACK FOR MULTIPLE REFLECTION MODEL103310462721610.21608/asat.2011.27216ENMostafaEI-ShershabyIs with Air Defense Collage , Alexandria, Egypt.OsamaMostafaIs with Air Defense Collage , Alexandria, Egypt.AhamedMashaalIs with Air Defense Collage , Alexandria, Egypt.Journal Article20190214Chaotic fluctuation of laser output is obtained at a relatively wide range of laser parameters. The dynamical behavior of semiconductor lasers with optical feedback from an external mirror was described by the rate equations modeled by Lang and kobayashi. Some models were numerically analyzed this behavior but in our work we extended the previous results by allowing two reflections, and multiple reflections in the extended cavity. It is found that the chaotic state be very sensitive to the higher order reflections when the reflection coefficient is large.https://asat.journals.ekb.eg/article_27216_c2fb9bd6e5e003444e8b5e0a912de728.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501NEW RATIO IMPROVING THE DIAGNOSIS OF NERVE SYNDROME104710542735910.21608/asat.2011.27359ENWaelFaroukElsayed Abd-AlazizSleetSerry. S.BesarM. EL.SayedGadallahAhmedGenedyJournal Article20190218Sensory nerve action potential is always characterized by three factor, amplitude, duration and waveform. In this paper we proposed an additive ratio (median to ulnar sensory nerve action potential amplitudes ratio) for improving the diagnosis of nerve syndrome while measuring sensory nerve action potential (SNAP). Orthodromic median and ulnar SNAPs were recorded and the respective ratios were calculated. Normative data for median nerve SNAP amplitude, ulnar nerve SNAP amplitude and the new ratio is obtained.https://asat.journals.ekb.eg/article_27359_e6c37717449ecbb19ef3cd6095b496f1.pdfThe Military Technical CollegeInternational Conference on Aerospace Sciences and Aviation Technology2090-067811ASAT Conference, 17-19 May 200520110501ANALYSIS OF TORSION ACTUATION IN ACTIVE THIN-WALLED SINGLE-CELL COMPOSITE BEAMS1142877910.21608/asat.2011.28779ENMoustafaKinawyResearch Engineer, Aerospace Research Center, Cairo, Egypt.Wagdy E.Abdel-GhanyAssociate Professor, Dept. of Design and Production AinShams University, Cairo, Egypt.Journal Article20190317A modified approach is developed to predict the deformation of active thin-walled single-cell active composite beam of general cross-section under general loading. The theory takes into consideration the transverse shear due to restrained warping, and the bending wall effect. The analytical model for the equations of motions consisting of six non-homogenous coupled differential equations of 14th order is used. Then a study is made on torsion actuation of beams .Then simplification is made to study the efficiency of possible types of torsion actuation techniques. Finally rectangular active box-beams are studied under three different torsion actuation techniques.https://asat.journals.ekb.eg/article_28779_9c88d6182b70f31e344cb3617763be61.pdf