bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact and bending analysis of composite scarf adhesive joints modified with MWCNTs at room and hot temperatures
Authors: Khashaba U A , Othman Ramzi , Najjar I M R
Published: October 2019

Scarf adhesive joints (SAJs) have attracted an increasing attention in joining/repairing of carbon-fiber reinforced epoxy (CFRE) composite structures due to their zero eccentricity, which provides better aerodynamic surfaces. This study evaluated for the first time, the performance of SAJs in CFRE composites under thermo-mechanical impact loads. The adhesive was modified with optimum percentage of multi-walled carbon nanotubes (CNTs). The impact tests were performed at room temperature of +25°C, +50°C and +75°C. The residual flexural properties of the unfailed impacted joints were measured using three-point bending test. Results from impact tests at temperature of 25°C, 50°C and 75°C showed improvement in the impact bending stiffness of the modified SAJs with CNTs by 8.3%, 7.4% and 11.8% and maximum contact force by 15.6%, 21.3% and 18.9%, respectively. The energy at failure of the CNT-SAJs was increased by 15.2% and 16.4% respectively at temperatures of 25°C and 50°C. At test temperature of 75°C the SAJs have hysteresis load-displacement behavior and energy-time curve with rebound energy of 35% and absorbed (damage) energy of 65%. The residual flexural strength of the modified and unmodified SAJs is 98.2% and 86.1% respectively, while their residual moduli have remarkable decrease to 71.7% and 81.3%.
Harmonic mitigation for power rectifier using passive filter combination
Authors: Monem O A
Published: October 2019

Power rectifiers are widely used in different industrial applications that deliver DC voltage supply for many types of loads like electrolysis cells, metal electroplating and other DC loads. These rectifiers act as nonlinear loads injecting harmonic currents to the AC mains with lots of troubles and negative impact on the utility grid and the load itself, like increasing losses, measurement error, protection device false tripping and distortion of the voltage at the PCC affecting other loads at the same point. For this reason, many researches focus on this problem and how to mitigate it. In this research, power analysis measurements are taken for 750 KW power rectifier feeding electrolysis cells and define the power quality indices compared to IEC 519 Standard. Passive filter is selected to mitigate the recorded harmonics. Two types of filters are designed. The first is three single tuned passive filter to mitigate the 5th, 7th and the 11th harmonics. The second type is 2nd order high pass filter to mitigate harmonics equal and greater than 13th harmonics. MATLAB simulation is performed to validate the proposed solution. The current total harmonic distortion can be reduced from 29.6 % to 1.5 % and supply voltage total harmonic distortion is also improved from 3.25 % to 0.62% which meet the international standard and improve the power quality of the voltage at point of common coupling.
Ground target localization and recognition via descriptors fusion
Authors: Kamel Mohamed M , Taha Hussein S , Salama Gouda I , Elhalwagy Yehia Z
Published: October 2019

Keypoint matching can be defined as locating the position of a particular point in two images precisely. Recently, keypoint descriptors have taken a great effect targeting to be powerfully invariant to rotation, scale and translation for improving target detection. The detection task is carried out by a reference-scene image matching to localize the desired target in the input scene. An innovative approach is proposed in this work to fuse the state-of-the-art feature descriptors ORB, BRISK for the sake of accurate ground target detection in two phases. Firstly, off-line phase, where the fused features are extracted from different perspective, azimuth angles of the desired target to build a comprehensive reference image representation. Secondly, on-line phase, where the fused features extraction task is carried out from the whole scene. Hence, it is matched with the stored reference one to find the keypoints correspondence. The outliers’ problem is eliminated using Random Sample Consensus (RANSAC) algorithm resulting in speeding up the matching procedure. The conducted comparative analysis has revealed the discriminative power of the fused features in localization and recognition tasks while keeping the proposed system works in real-time.
Design of a roll autopilot for a skid-to-turn guided missile
Authors: Ali K M , Abozied M , Arafa I , Elhalwagy Y
Published: October 2019

the design of autonomous systems is a growing research field which attract an increasing interest in various civilian and military applications. The design of control system can be considered a leading factor for developing any autonomous system. In this paper devoted to a missile autopilot which should achieve specific characteristics and performance criteria to ensure the overall system stability to track the desired commands in the presence of high dynamics and different uncertainties with high accuracy. The investigation of accurate missile 6DOF model is developed and linearization has been performed for designing the proper controllers for the pitch and roll channels and choose the optimum trim points based on system dynamic pressure. A design of lead compensator classical controller is presented to meet certain requirement of both time and frequency characteristic to ensure the system stability. The designed autopilot is evaluated using Matlab simulation is carried out for evaluating the proposed missile autopilot controller performance, the proposed controller presented sufficient performance during flight and simplicity, reliability, and availability for implementation in real time applications.
Depolarization diagnosis of PWAS used for EMI based structural health monitoring system for composite plates
Authors: Amin Mostafa S , Salem Mohamed A M
Published: October 2019

Implementation of Electromechanical Impedance (EMI) as a technique to carry out Structural Health Monitoring (SHM) has been proved to be such effective tool in the last two decades, especially for structures made of composite material. EMI technique is the revolutionary evolution of the conventional Vibrational Based Damage Identification (VBDI) techniques. Unlike VBDI techniques, EMI technique has the privilege of employment tinny permanent piece of equipment which is known as Piezoelectric Wafer Active Sensor (PWAS). Although it has such advantage, it brings the necessity of continuous and robust diagnosis process of the PWAS used in the SHM system to ensure that output signals are caused by real variation of the modal parameters for the host structure rather than being occurred due to degradation and-or physical damage of the PWAS system itself. The study presented in this paper is focused on the self-diagnosis of PWAS used to carry out SHM via implementation of EMI technique. The main concern of this research is to study the ability of EMI technique to determine depolarization of PWAS and its influence on the performance of EMI based SHM system employed for structures made of composite plates. The used specimen (s) is / are underwent controlled excitation over desired frequency range, the imaginary part of admittance is plotted over desired frequency range. The whole process is then repeated for different levels of depolarization for the same specimen (s). The modeling process is carried out using a finite element commercial package, ANSYS v.15.0 in which multi-physics-based modeling can be used for such coupling field of piezoelectricity. MATLAB code is written to process the output data received from numerical simulations into counterpart spectrum and to calculate the statistical damage index Root Mean Square deviation (RMSD) that is used in damage detection. The calculated RMSD found to be non-zero values, which means false prediction. These results shows how important to have self-diagnosis for PAWS used in SHM system for further reliable measurements and data interrogation using EMI technique.
Design and implementation patch antenna with different fractal shape
Authors: Allam A. M. M. A. , Abo Sree Mohamed Fathy , Ibrahim Muhammad Aly
Published: October 2019

This work presents the effect of fractal shapes on the patch antenna. It is a conventional rectangular patch antenna with dimension of 9.2 mm × 6.94 mm. It is implemented on FR-4 lossy substrate material with relative permittivity of εr = 4.3, thickness of 1.6 mm and loss tangent of 0.025. It is feed through a microstrip line with dimension of 6 mm × 3.11 mm. The overall dimension of the antenna is 35 mm × 30 mm × 1.6 mm. It operates over a frequency band from 8 GHz to 12 GHz with central frequency 10 GHz. Application of Pythagorean tree Sierpinski gasket, and Koch curve is to decrease the bandwidth and increase the gain of the designed antenna. The performance properties of the antenna such as resonant frequency, radiation pattern, and gain were examined by simulation. The design is implemented through CST microwave studio and measured through network analyser.
Performance of LTE downlink communication system in presence of electronic warfare spot jamming
Authors: shabana Gamal H. , Shaheen Ehab M.
Published: October 2019

Wireless communication is one of the principally active zones of tools development and has become necessary part of everyday life. Simulation of wireless communication systems accurately is very important for predicting its performance under different scenarios. Long-Term Evolution (LTE) is named by next generation wireless communications. It is a standard for high-speed wireless communication for mobile phones and data terminals. In this paper, the performance of standard single-input-single-output (SISO) LTE Frequency Domain Duplex (FDD) downlink (DL) signal in additive white Gaussian noise (AWGN) channel is evaluated in two scenarios without jamming and in presence of electronic warfare spot jamming. Firstly, the performance of the standard LTE communication system in absence of jamming is investigated by calculating the probability of Bit Error Rate (BER) and Frame Error Rate (FER) versus Signal Noise Ratio (SNR). Secondly, the performance in presence of electronic warfare spot jamming scheme is investigated by constant Jamming to Signal Ratio (JSR) and different values of the normalized jamming bandwidth. In order to illustrate the impact of jamming on the standard LTE DL wireless communication system, the measurement is evaluated by using the aid of SystemVue software program.
Simulation and modelling of flight missile dynamics and autopilot analysis
Authors: Kamel Mohamed M , Ali Karim M , Abozied Mohammed A H , Elhalwagy Yehia Z
Published: October 2019

In the current paper, nonlinear modelling and dynamical analysis of a surface to surface missile with both aerodynamic and thrust vector control is investigated. Aerodynamic force and moment modelling of the presented missile includes the challenging high angle of attack aerodynamics behaviour and the so-called hybrid control, which utilizes both tail fins for stabilization and rudder vanes as control surfaces. Then, concerning relative rotation between bodies, the missile aerodynamic model is built by Leabedev aerodynamic calculations software. After using the generated aerodynamic data obtained the required aerodynamic stability derivatives, the required transfer functions are resolute based on the equations of motion of the missile. The missile dynamic motion in pitch and roll channel are analysed. The guidance and control strategy are developed through an actuation system and autopilot design in the four channels based on the poles assignment technique. The roll autopilot is constructed to regulate the roll angle of the front body of the missile which is the controlled part, for the command signals generated by the guidance laws both pitch and yaw autopilots are designed to realize. The guidance command is in the form of rate of change of flight path angles of the missile with time.
Implementation and validation of autopilot design for vertical missile systems
Authors: Ali K M , Abozied M , Arafa I , Elhalwagy Y
Published: October 2019

high nonlinearity and deficiency in control at boost-phase due to high angle of attack during maneuver and low velocity in the vertical launched missile. The necessity of high maneuverability and vertical launching require thrust vector control additional to aerodynamic control. effectively increasing the alertness of the missile against air defense threats by using That mixture usage of aerodynamic and thrust vector controls. Critical design of guidance and control is difficult and critical due to requirement and the rapidly changing dynamics of this type of missiles. The aim of this paper is to design autopilot with aerodynamics surfaces(fin)and thrust vector control by system characteristics reflection. by using Missile Lebadev Program (MLP) the model is developed based on the configuration of operating missile. Two control systems are aimed, which usages the command trajectory result optimization and the pitch rate controller which tracks real-time guidance command. The guidance and control strategy are developed through an actuation systems and autopilot design in the two channels pitch and roll based on the poles assignment technique. The investigation of the performance of pitch autopilot and its ability to reject disturbances due to cross-coupling between pitch and roll channels showed that, the pitch channel can reject disturbances within average time 3.5 sec.
Composite solid rocket propellant based on GAP polyurethane matrix with different plasticizers
Authors: Boshra Islam K. , Elbeih Ahmed , Mostafa Hosam E.
Published: October 2019

Glycidyl azide polymer (GAP) has been prepared and studied for its application as polymeric matrix for composite solid rocket propellants (CSRP). Different CSRP based on GAP polymeric matrix with different plasticizers were prepared. A cross-linker based on trimethylol propane (TMP) and dibutyltin dilaurate (DBTDL) was added to the GAP matrix to ensure curing completion of the prepared CSRP. The viscosity and shore A of all the prepared CSRPs during the curing process were measured continuously. The mechanical properties of the cured CSRP were determined. The ballistic performance, burning rate at operating pressure and specific impulse were determined using standard a modified six inch rocket motor with 16.25 mm nozzle. By comparing the results, it was concluded that the plasticizer; dioctyl azelate and dibutyl phthalate are not compatible with GAP matrix. In addition, CSRP based on GAP has specific impulse and burning rate slightly higher than the traditional HTPB based CSRP.
Involving PETN explosive into polyurethane polymer matrix for reactive armour applications
Authors: Elnogomy Mohamed , Elshenawy Tamer , Elbeih Ahmed , Radwan Mostafa , Yehia Mohamed , Baraka Ahmad , Elsayed Mohamed A. , Gobara Mohamed
Published: October 2019

This paper describes some formulations of plastic bonded explosives (PBXs) in the form of flexible material (sheet explosive) for military and civilian applications. Different compositions based on (70 wt%, 75 wt%, 78 wt%, 80 wt%) of PETN as high explosive filler were prepared by casting technique using HTPB polyurethane binder material. The production technique of the prepared explosive sheets was described in this research. Sensitivity to impact and friction were also measured. In addition, heat of combustion was determined. Besides, the detonation velocity was measured experimentally and the detonation characteristics were calculated using EXPLO 5 thermodynamic code. For comparison, standard commercial available plastic explosives such as EPX-1 and Datasheet C were studied. By comparing the obtained results, several relationships based on the results were observed. A good agreement between the measured and the calculated results was confirmed. Sample containing 78 wt% of PETN bonded by the polyurethane matrix is an optimum for the application of reactive armours.
Characteristics of a paste explosive (EPX-P20) used in explosive bolts for spacecraft’s applications
Authors: Elbeih Ahmed , Abdelhafiz Mahmoud , Hussein Ahmed K. , Wafy Tamer Z. , Elshenawy Tamer , Baraka Ahmad , Elsayed Mohamed A. , Gobara Mohamed
Published: October 2019

An explosive charge, located within a machined cavity in a bolt, provides the energetic stimulus required for cleanly bolt fracture. The shock wave produced fom the explosion causes tensile fracture along the bolt itself with minumum fragmentation and helps to control the separation process of the satellite from its rocket. In this study, EPX-P20 is a paste explosive in the research stage. EPX-P20 is based on PETN (pentaerythritol tetranitrate) bonded by polydimethyl-siloxane binder matrix. A computerizing mixer plastograph was used for the production of EPX-P20. The internal energy of combustion was measured and used to determine the enthalpy of formation. Sensitivity against both friction and impact stimuli were determined. The detonation properties were calculated theoretically using the EXPLO 5 soft code, while the detonation velocity was determined experimentally. For comparison, several commercial available explosives such as; Sprängdeg m/46, Formex P1, Semtex 10 and EPX-1 were investigated. It was proven that EPX-P20 possesses the lowest velocity of detonation while maintaining its very low sensitivity. Interesting inversely proportion relationship amongst the measured internal energy of combustion and the calculated heat of detonation was observed. The produced paste explosive might be used in explosive bolt for space craft’s applications.
Parametric study for reducing emission characteristics using different computational schemes
Authors: Kayed Hatem
Published: October 2019

The present study numerically predicts emissions (NOx & CO) characteristics issued from swirl burner using different computational schemes adopted in ANSYS 17.2. Various turbulence models were tested and compared in a structured grid having an average skewness of 0.04. RSM model shows the best results in predicting the central toroidal recirculation zone for such severe swirling flow (S>0.6). Three different schemes of combustion modeling were also tested and compared. Flamelet PDF model was preferred among other combustion models for its potential to consider non-equilibrium chemistry, where its choice was recommended form many studies in the literature. A radiation heat transfer analysis was carried out using P1 radiation model to account radiation effects in estimating NOx and CO concentrations. The effect of varying swirl ratio, excess air, diluting fuel with N2 and CO2, oxidizer preheating, and oxidizer composition on emissions (NOx and CO) reduction strategy concluded that increasing the swirl number, excess air factor, and (N2 and CO2) mixing ratios have a considerable influence on NOx and CO emissions reduction. While increasing the preheating temperature, and the oxidizer Oxygen concentration leads to an increase the NOx and CO emissions. Hence, a considerable reduction in NOx and CO formation was apparently observed by lowering the peak flame temperature less than 1800 K. These predicted outcomes are in agreement with measurements data published in the literature.
A road map to the detection performance of LFM-PC search radars with CFAR detectors
Authors: Abdel Latif Soliman Mohamed Samir
Published: October 2019

Pulse Compression (PC) radars are used to resolve the problem of designing long range radar systems with excellent range resolution. PC provides radar system with additional processing gain that enhances its detection capability. Among the different types of pulse compression waveforms, Linear Frequency Modulated (LFM) signals are the most tolerant to high Doppler shifts. This is why LFM-PC radars are widely utilized with high speed targets. However, the literature lacks a complete mathematical or simulation model to evaluate the its detection performance. This paper introduces a typical simulation model for search radar that is verified mathematically. The proposed model includes matched filter (MF), moving target detector (MTD), two different constant false alarm rate (CFAR) algorithms and LFM signal sidelobes on radar detection are to be considered. Two simulation models are introduced. Firstly, the Matlab simulation is introduced to verify the mathematical model and the theory. Secondly, the SystemVue simulation is applied to be used in the future work with the hardware in the loop facility.
Condition-based monitoring of a small centrifugal pump by vibration analysis
Authors: Abd-Elaal M , Lotfy M , Nabil T , Eldomiaty A
Published: October 2019

Rotating machinery vibration problem is the most significant restriction which control the life time and may cause disastrous failure of the entire system. The vibration monitoring is the main element for any customized maintenance program to guarantee power plant availability and minimize danger of predictable failures. The present work is an experimental study on a small centrifugal pump running in healthy and intentionally defected to show the difference in the vibration spectral and time domain. Triaxial acceleration measurements were made at the shaft of the pump. The most dangerous case of vibration denoted by the highest amplitude as determined as well as its corresponding frequency. The most serious case was the pedestal looseness with full flow rate which cause a vibration of amplitude of (0.104g) at frequency (47Hz). The unacceptable vibration, as classified according to ISO 10816 to have amplitude of (0.5g) for small machines within this rang of acceptable vibration it was not difficult to predict the artificial defects mode in the pump and demonstrated the capability of condition monitoring.
Vibration caused by swing check valve closure
Authors: El-Zahaby Aly M , Zakaria Mohamed Y , El-Samadony Yasser A F , Ismail Ibrahim A
Published: October 2019

Check valve or non-return valve is a commonly used component in fluid control systems, the function of the check valve is to allow the fluid to flow in one direction and prevent it from flowing backward in the opposite direction. There are many types of check valve that differs in structure, material, theory of operation, applications, installations constraints, etc. The swing check valve type has many advantages like lower pressure drop, high valve flow coefficient, ease of maintenance, etc. In this paper, the swing check valve type will be investigated using a new mathematical model that avoids the inaccuracy in explicit models and time consumption of evaluating different coefficients in implicit models. The present model is validated by comparing to experimental data. Investigation of the swing check valve is carried out in order to determine the vibration produced by its closing action and closing response. Also the effect of equipping the swing check valve with a torsion spring is investigated to figure out the spring effect on the valve induced vibration.
PID vs. Backstepping Control for Cooperative Quadrotors Unmanned Aerial Vehicles
Authors: Mahfouz M. , Taiomour A. , Ashry Mahmoud M. , Elnashar G.
Published: October 2019

Formation reconfiguration is one of the most important tactics used in the field of cooperative Unmanned Air Vehicles. In this paper, formation reconfiguration for a team of vertical takeoff and landing quadrotors is managed by a classical approach of proportional-integral-derivative (PID) controller. PID controller is designed to regulate the attitude and the altitude for every quadrotor of a cooperative team respecting the separating span and velocity constraints. PID controller results are compared with a backstepping controller developed for the same system. The mathematical model of the propositioned system is derived initially, and then a PID controller using simplex and genetic algorithms is designed qualifying the cooperative quadrotors to track the desired trajectories. Simulation results present the assessment of PID control strategy along with backstepping control strategy in different scenarios including proposal flight mission in obstacle-free surroundings, and obstacle-laden surroundings. Noise attenuation and disturbance rejection are examined for both controllers to check the robustness of the system.
Reliability prediction of on-board subsystem satellite by Monte Carlo methodology
Authors: Zoalfakar Said H. , El Badawi Rehab E.
Published: October 2019

This paper presents a case study that aims to develop a hardware design for the pc to the satellite, supported fault-tree design and calculations of dependableness. The on-board pc of a satellite, inserted into the on-board management system, has functions of receiving, process and distribution of commands to the subsystems and payload of the satellite; and exploit, formatting, storage and transmission of measurement from subsystems and payload. The most necessities of associate on-board pc are high dependableness, capability of real time process, resistance to radiation, and minimizing power consumption, volume and mass. Enlarged dependableness is achieved by the fault tolerance technique that relies on adding redundancy to the system, or the utilization of elements with high price of individual dependableness. During this work, hardware redundancy techniques are thought-about. First, a pc is meant and its dependableness is calculated, for a mission of one year period. Mission dependableness goal isn’t earned during this calculation. So as to extend dependableness, two kinds of fault tolerant redundant architectures are analyzed, with their various reliabilities calculated for the identical amount of the mission.
Agile mission optimization for a constellation of earth observation satellites
Authors: Abbas A M , Meselhy K T , Moughith W S , Omer A A
Published: October 2019

Today’s Earth Observation Satellites (EOSs) have complicated missions with an agility capability. For this reason, a great importance for satellite mission optimization problem has been arisen. In this paper, a multi-objective equation has been formulated which contains three selected objectives (Gain, image quality and time execution). There are three constraints (Target exclusiveness, due date and transition time) which have been selected and presented by three equations. Satellite Tool Kit (STK) has been used to simulate the relation between satellites and customers’ targets. The output opportunities from STK have been saved in an excel sheet and they will be used as inputs for our problem. Genetic Algorithm (GA) has been used as one of the optimization techniques to solve this problem and it has been applied by using Matlab program and its graphical user interface. The result from solving our problem is a plan which contains selected targets numbers, satellite numbers, target’s gain, shooting time, combined angle, target’s objective function value and the total objective function value. In this paper, a case study has been presented assuming there is a constellation of four (4) satellites (Superview constellation), thirteen (13) random targets and the required output is an optimum daily plan for shooting.
Thermal behaviour of MWCNT/ammonium perchlorate particles
Authors: Yehia M , Mostafa Hosam E , Wafy Tamer Z , Abdelhafiz Mahmoud
Published: October 2019

A lot of attention has been given to incorporation of carbon nanomaterials (CNMs) including carbon nanotubes (CNTs) in ammonium perchlorate (APC) based solid propellants to enhance their final performance. (CNTs) has many applications in the energetic material field due to its large surface area and surface energy. This study reports on catalysed ammonium perchlorate (APC) by multi wall carbon nanotube (MWCNT). MWCNTs were successively encapsulated with APC particles by using modified fast-crash solvent–antisolvent technique and characterized by scanning electron microscope (SEM) and Energy dispersive X-ray spectrometer (EDX). The catalytic performance of MWCNT on the thermal behaviour of ammonium perchlorate (APC) was analysed using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Interestingly, the effect of MWCNTs on the thermal decomposition of APC where the results showed that encapsulated APC with 1% MWCNT show significant decreasing in the high temperature of decomposition APC from 452.8°C to 390.1°C and MWCNTs giving an increase in total releasing heat of APC by 130 %. The results confirmed that MWCNTs are a novel catalysing agent on the thermal degradation of ammonium perchlorate which has a direct impact on the burning behaviour, performance and combustion regime of the solid rocket propellants.
Mechanical behaviour of rubber hybrid composites
Authors: Mousa Bassant Hany , El gamsy Ramadan , Abdel Latif Mohamed Hazem
Published: October 2019

Recently, a lot of researches are directed to recycling of waste materials such as waste tires and marble and granite dust (GM). The management of solid wastes is essential to prevent the harmful effects and hazards associated by the contamination of these wastes. Waste tire rubber particles (WTRP) are added to high density polyethylene (HDPE) matrix to increase the impact strength of HDPE, while it results in the decrease of other mechanical properties. GM is added to this mixture to modify some mechanical properties such as hardness and compressive strength, this mixture results in a novel hybrid composite. The effect of using different GM wt.% on different mechanical properties of the composite is studied. Mechanical testing such as three-point bending, Charpy impact, compression and shore D hardness is implemented according to ASTM standards and Scanning electron microscopy examination of the microstructure of WTRP-HDPE-GM hybrid composite is used to support the explanation of the results.
Firing test and evaluation of coaxial pulsed plasma thruster
Authors: Othman M A , Elzahaby Aly M , Makled Ah El-S , Khalil M
Published: October 2019

For many reasons, electrical propulsion systems are the most expected in space; they are suitable for researchers because they are effective, easy to design and applicable in space. One of the most important parameters that could assess the performance of the propulsion system is the problem of measuring the very low thrust of pulsed plasma thrusters (PPTs). Various test beds, including indirect designs of measuring systems such as pendulums and optical measuring systems, can measure the thrust with very high precision, but it is very complicated.

This paper presents the firing test of a new designed coaxial pulsed plasma thruster for proofing the concept and then the thrust is measured by a new simple test bed using a rod in accordance with a loading cell (0-100 gf.) which can measure thrust accurately after good calibration up to μgf. In a medium-sized vacuum chamber (VC) (10−5 bar, D= 1 m and L= 1.4 m), a coaxial PPT is designed and tested under environmental conditions in space. Four proofs of concept took place until the experiment was adjusted and six experiments were carried out to measure the thrust using the new test bed under various operating conditions. Evaluation of the system is presented too and the maximum thrust obtained is 0.68mN at the discharge voltage equals 7kV and the 12kV voltage of the spark plug initiator and the efficiency equals 10%. The steps of fabrication of the coaxial PPT and steps of measuring the thrust is presented in the paper beside the result charts of the thrust under different operating conditions.
Mobile robot position estimation using Euler-Maruyama algorithm
Authors: Abd Elfatah Mohamed G , Zaky Hany Nasry , Gharib M
Published: October 2019

Mobile robots became very important and more familiar in commercial, industrial and military applications. In many unmanned vehicle applications, sensors and control systems are mounted on mobile robots to identify the surrounding environment for obstacle avoidance. This work aims to estimate the mobile robot location to compensate the time delay problem which appears in teleoperation. According to the stochastic nature of the mobile robot teleoperation, the kinematics equation of mobile robot will be converted into stochastic differential equations (SDEs). Euler-Maruyama algorithm used as it is one of the most popular numerical algorithms to approximate SDEs solution. A simulated results for the solution is produced which seem to be good comparing with mobile robot ideal path simulation.
ICI and PAPR enhancement in MIMO-OFDM system using RNS coding
Authors: Youssef M I , Emam A E , Abd elghany M
Published: October 2019

The Inter-Carrier-Interference (ICI) and the Peak-to-Average-Power Ratio (PAPR) of the transmitted signal are considered as bottlenecks in the utilization of Multiple-Input-Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems, which caused a significant performance degradation. In this paper Residue Numbers as a coding scheme is impeded in MIMO-OFDM systems, where the PAPR values are analysed and compared to non-RNS coding systems, and the ICI levels are measured and evaluated with respect to the conventional ICI mitigation techniques as pulse shaping, windowing and self-cancellation techniques implemented in MIMO-OFDM system. The ICI errors, Bit-Error-Rate (BER) and the Complementary Cumulative Distribution Function (CCDF) for MIMO-OFDM system with Residue Number System (RNS) coding are analysed and evaluated. The results demonstrated a performance enhancement of the transmission model over the system without RNS implementation.
Outdoor RF spectral study available from cell-phone towers in sub-urban areas for ambient RF energy harvesting
Authors: AbdelGhany Omar M , Sobih Ayman G , El-Tager Ayman M
Published: October 2019

In this paper, outdoor RF spectral survey results in a sub-urban area are demonstrated. this work was carried out to explore and define the ambient RF signal sources available in the populated environment so as to select the frequency bands most suitable for designing RF energy harvesting circuits. Referring to the Egyptian frequency allocation chart, the ambient RF power sources within the spectrum of 0.5 to 2.2 GHz has been detected and measured to cover the mobile downlink frequency bands (2G, 3G and 4G) and the digital TV broadcasting bands which represent the most favourable frequencies for ambient RF energy harvesting circuits which is convenient for outdoor applications that needs power supply source in the range of microwatts. According to the available parameters of the cellular network standards, the measurement results were compared with the analytical empirical path loss propagation models focusing on sub-urban areas which provide an estimation of the median path loss as a function of distance and the urban terrain classification. The models that are discussed in this paper are HATA Model, Ericsson Model and ITU-R Model. It is found that HATA model can be used to give the best predictions with minimum error for losses and received power levels. Based on the measured data,
a designer can decide the maximum distance away from a cell-phone tower that meets certain detection sensitivity. This study is useful for ambient RF energy harvesting designers.
Spray combustion characteristics of effervescent atomizer inside experimental furnace
Authors: Wilson Safwat A. , Asar Gaber M. , Elshahawy Eslam M.
Published: October 2019

The spray combustion characteristics of “inside-out” effervescent atomizer at low injection pressure have been investigated in the present study. The atomizer is mounted on experimental furnace cooled by separate segments water jacket the plain orifice atomizer is powered by diesel fuel and air as atomizing gas. The study shows the influence of A/F ratio, atomizing gas to liquid mass ratio (GLR), injection pressure, and exit orifice diameter on flame temperature distribution inside the furnace. cooling water heat flux, stack temperature, and combustion efficiency. The air to fuel mass ratio (A/F) varies from 20 to 50 Kgair/Kgfuel, and operating pressure varies from 0.5 to 2 bar. The results show that the increasing on A/F ratio decreases the flame length, and exhaust gas temperature, while the combustion efficiency increases. It was found also that, when using A/F ratios higher than 30 the combustion efficiency becomes greater than 90%. Where, the increasing on operating pressure increases the flame maximum temperature and heat transfer to cooling water. Moreover, increasing the combustion efficiency. The results could enrich our knowledge of effervescent spray combustion characteristics and achieving higher combustion efficiency with low pollutant emissions.
Investigation the effectiveness of using heat pipe on the temperature uniformity distribution over the SC equipment panel
Authors: Abdou M , Elzahaby Aly M , Khalil M
Published: October 2019

The heat pipe is a thermal device which allows an efficient transport of thermal energy. In this paper parametric study has been achieved to investigate the importance of using heat pipes about the uniformity of the temperature distribution over the equipment panel of the spacecraft (SC), which is a part of a real thermal control subsystem. Heat pipe analytical solution is used as a guide for design and geometrical parameters selection. The design of SC equipment panel radiator and a parametric study of the heat pipe are obtained numerically using Thermal desk top program (TDT). The space environment and the spacecraft operational conditions have been simulated by TDT program. Heat pipe prevents the hot spots which can be occurred due to the different equipment heat dissipation. The selected heat pipe design approach incorporates a conservative reliability philosophy and provides maximum operational flexibility.
Performance analysis for aerial-towing system
Authors: Khalil Mostafa
Published: October 2019

The dynamics of open chain systems have been widely investigated as a result of its increased applications such as aerial towing system, submerged towed cable applications, robot manipulators, and bio-mechanical applications. In this study, a practical engineering system, Mine Clearing Line Charge MICLIC system is taken as an example for an open chain system with accelerated end and varying number of segments. To validate the proposed model, a comparison between two different finite segment methods namely Kane’s method and Riccati transfer matrix method of linear multibody system (Riccati-MS-TMM) have been performed for a large open chain system. Results show that computational speed of Riccati-MS-TMM outperforms Kane’s method due to its huge matrix size to be solved. Then, using a predefined rocket motor total impulse, a parametric study has been performed on MICLIC system to illustrate the impact of different rocket motor thrust profiles on the resulted flight performance including the missile range, flight time, maximum tension applied on the rocket towing bridle, and the missile stability.
Flight dynamic model for low earth orbit satellites
Authors: Alshamy Hossam M. I. , Makled Ah. El-S. , Elhalwagy Y , Hendy Hossam
Published: October 2019

Low Earth Orbit satellite(LEO) missions have potentially attractive features such as low launch cost, and wide remote sensing applications.

There are three vital missions during the satellites life time including orbit transfer from the parking to the operating orbit, maintaining the operating orbit and de-orbiting mission to a disposal orbit at the end of the satellite lifetime according to the standard disposal orbit law. The mathematical model has been implemented to study various LEO mission orbits including the three vital missions.

The mathematical model evaluates the required performance parameters, velocity budget, number of manoeuvers, duration and consumed propellant mass for each mission.

The mathematical algorithm is carried out using Matlab/Simulink, the complete mathematical flight dynamic model has been verified through comparisons with the generated mission scenarios from Satellite Tool kit (STK), the graphical user interface is designed to display the model.

The carried out algorithm can be applied in satellite mission design to help predicting the parameters for each mission to minimize the risks and intensive tests. it can be considered as powerful tool to design and analysis LEO satellite missions.
Optimization Analysis of Minimum Flat Curve Radius of High Speed Maglev Line with Design Speed of 500 km/h
Authors: Jiang Fujie , Sun Xiangdong , Li Huibai , Huang Jingyu , Li Dongshuai
Published: October 2019

Firstly, based on the traditional circuit design method, the theoretical calculation value of the minimum radius of the flat curve under the design speed of 500 km/h is calculated in this paper; Through the analysis of the structural characteristics of the TR08 high-speed maglev train and the degree of freedom of each component, a 129-DOF high-speed maglev vehicle-line dynamics model is established by using the multi-body dynamics software SIMPACK; And using the modle to simulate and analyze the influence of the radius of the flat curve on the dynamic performance of the vehicle. Finally, according to the simulation results, the theoretical calculation of the minimum radius of the flat curve is optimized and adjusted, and the minimum radius recommended value of the flat curve that satisfies the dynamic evaluation index is obtained. After the simulation optimization, the unbalanced lateral acceleration and the vertical acceleration dynamic response of the vehicle passing through the designed curve section are significantly reduced, and the ride comfort of the passengers is good.
Finite Element Analysis of Residual Stress in Welded Joints of T91 Steel
Authors: Wang Zhi-ling
Published: October 2019

The pressure equipment is the key equipment in the petrochemical industry, natural gas chemical industry and coal chemical industry. Without safe and reliable pressure equipment, advanced process industry cannot be realized. It is important of the quality assurance of pressure vessel in order to prevent the failure of pressure vessel, especially some rupture accidents. One of the key reasons for quality assurance of pressure vessel is the treatment of residual stress in welded joint. In this paper, the working stress and welding residual stress of the thick plate of pressure equipment material and the welding joint of pressure equipment have been measured and analyzed successively by means of actual stress measurement and finite element simulation analysis. The influencing factors of welding stress are introduced, and the control of residual stress is analyzed and some suggestions are put forward in this paper.
Sliding Mode Variable Structure Control Strategy Applied on Position Servo System of EMA
Authors: Wang D Y , Gao S J , Yan M , Zheng S C
Published: October 2019

This paper introduces the basic elements of Electronic-Mechanical Actuator (EMA), and gives the equations. The mathematical model-state equations is established based on the basic equations, and the sliding mode variable structure control strategy, based on the reaching law is applied to control the position servo of EMA. We design a position-speed integrated sliding mode variable structure controller. The models of EMA machinery, electrical motor and controller are established in AMESim and Matlab, and joint simulation is carried out. Finally, this control strategy is compared with the three loop PID control strategy, and the experiment is carried out. The result shows that the sliding mode variable structure control strategy based on reaching law used to control EMA can improve the frequency response and control accuracy of the system, can also improve the dynamic performance of the position servo system.
Investigation on Polymer Composite Materials Wear Reinforced by Microparticles of Jatropha Curcas L. Waste
Authors: Müller Miroslav , Valašek Petr , Tichý Martin , Ruggiero Alessandro , D’Amato Roberto
Published: October 2019

The subject of the paper is a research on the wear resistance by friction against loosely fixed abrasive particles on a polymer composite material reinforced by waste microparticles from a pressing process of Jatropha curcas L. seeds with concentration from 5 to 20 wt.%. The seed pressing waste was used in form of Whole seeds cake (WSC), Seed shells (SS) and Seed kernels cake (SKC). The waste, which is difficult to further utilize for its inability to use as feed, arises at the pressing process of Jatropha Curcas L. seeds. A matrix of composite materials was epoxy-based. The wear tests were performed by the device Tester T-07 according to GOST 23.208-79. An addition of the filler significantly increased the wear resistance by friction against a rubber wheel with loosely fixed abrasive particles of sand. The wear resistance was increased up of 69% to 82% at tested polymer composite systems against matrix (resin). Composites materials with the filler Whole seeds cake (WSC) achieved the best results.
Numerical Investigation of Hybrid of Eglass and Basalt Fiber Reinforced Epoxy Tube Pressurized Internally
Authors: Almula Thamir A. D. M. S. , Khuder Ahmad Hassan , Yahya Mohd Yazid , Ayob Amran
Published: October 2019

The composite hybrid pipe is a novel structure made of concentric composite multilayer possess improved thermal and mechanical properties better than its original components. At variance experimental analysis, the numerical studies on the structure and behavior of composite hybrid natural fiber reinforced epoxy pipe materials pressurized internally seem lacking. In this study, numerical analysis was carried out for three different stacking plies of composite hybrid natural fiber ±55° basalt and Eglass fiber reinforced epoxy tube which was tested under the subjection for three modes of applied load, the hoop and longitudinal tensile tested as well as subjection under biaxial internal pressures load in accordance to ASTM’s standard to investigate the mechanical behavior and the optimal configuration among them. Also, analyzed the comparable three types of hybrid natural fiber (basalt)/Eglass reinforced epoxy with pure ±55° Eglass reinforced epoxy and pure ±55° basalt reinforced epoxy numerically to predict the performance for the hybrid over the pure E-glass and basalt fiber reinforced epoxy composite pipe as a good replacement to meet the different demand of applications in the pressure pipelines. Also The three stacking plies types of hybrid composite pipes were compared with the pure E-glass and basalt fiber reinforced epoxy pipes. All samples were fabricated using a dry filament wound CNC machine with ±55° orientation angle, then infused with epoxy resin using vacuum infusion procedure (VIP). Numerical analysis was carried out using finite element commercial code ANSYS V14.
Micro-electrochemical evaluation of α- or β-type titanium alloys
Authors: Lin Junhui , Lu Jiafei , Dan Zhenhua , Ding Yi , Chang Hui
Published: October 2019

In order to evaluate electrochemical stabilities of α, β phases, the micro-electrode techniques was employed to test the micropolarization behavior of α-type pure Ti and β-type Ti15Mo alloys. The comparison between macropolarization and micropolarization curves demonstrates that the α-type pure Ti alloy tends to exhibit the uniform corrosion, on the other hand, the pitting corrosion is the main form for the β-type Ti15Mo alloys. The α grains with different orientations shows similar polarization behavior, but the polarization behavior of those β grains are strongly affected by their crystalline orientations, particularly the worse electrochemical stabilities of β grains with (200)-dominance. The corrosion potential and corrosion current density of α-type pure Ti is lower than β-type Ti15Mo alloys. The α grains have better electrochemical stabilities in comparison to β grains, which indicate that the α+β dual-phase Ti-6Al-4V ELI alloys is highly possible to suffer from the preferential dissolution of β grains in free immersion condition and/or polarized states. Finally, by combining the SEM, EDS and polarization curves of dual-phase Ti-6Al-4V ELI alloys, it is concluded that β phases are corroded prior to α phases.