bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric optimization of non-prismatic micro-plates to reduce stiffening and curling initiated during fabrication
Authors: Bakeer B , Elsabbagh A , Hedaya M 
Published: August 2021

Abstract
Microelectromechanical devices such as accelerometers, gyroscopes, pressure sensors, and radiofrequency (RF) switches are widely used in aerospace applications. Reduction of stiffening and curling initiated during fabrication of these devices is one of the challenging issues in MEMS design. Reducing response time is also favorable in some applications such as RF MEMS switches. This paper aims at reducing stiffening, curling, and increasing the natural frequency for three well-known designs of micro-plates with fixed-fixed supports. To achieve these objectives, a parametric size optimization is carried out. For comparison purposes, same volume is set as a constraint for all three designs. Compared to conventional rectangular micro-plate, a reduction of 34% in stiffening in design 2, and 44% in curling in design 3. Design 1 showed the maximum fundamental natural frequency. Thus, it is predicted to have the lowest switching time. Moreover, design 2 showed the maximum critical buckling temperature, extending the operation range of the device. The effect of changing micro-plate material is also studied in this paper.
Factors affecting Failure mode and load of rubber polyester composite joint
Authors: Mousa B H , Azab N A , Bassioni G , Abdellatif M H 
Published: August 2021

Abstract
The joining of rubber polyester composite is affected by design and geometry parameters. These parameters affect the failure load of the composite joint and the failure mode. Catastrophic failure modes should be avoided, and the optimum parameters are selected to achieve a progressive failure that could be observed. Geometry parameters such as the edge distance and the center distance between holes are tested under tensile loading to get the optimum values. Design parameters such as tightening torque of bolt and washer size are also tested under tensile loading, and their effect on the failure load is obtained and studied. The failure modes are investigated under the digital microscope in each case. It is found that the failure load increases by increasing the edge distance, the tightening torque, and decreasing the center distance between holes. The optimum washer size is varied according to the used tightening torque. The optimum obtained failure mode in tests is a mixed - mode of bearing and net tension modes.
An investigation of plasma sprayed nickel-based and pure aluminum coatings on austenitic stainless steel AISI 304
Authors: Hamed K. , El-Mahallawy N. , Mokhtar M.O.A. 
Published: August 2021

Abstract
Atmospheric Plasma Spray (APS) is one of the most leading industrial techniques for protective coating, by improving the performance of parts in the thermal barrier, and wear resistance. Ni-Al alloys are very effective players in the field of design of protective coatings. Accordingly, mixed Al, Ni/Al, and Ni5Al powders were applied on 304stainless steel substrate to develop plasma sprayed coatings. The effect of different compositions on microstructure, microhardness, and porosity was measured. The microstructures of the as-deposited films were characterized utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness measurements. The results showed the formation of two intermetallic compounds, namely: NiAl and Ni3Al. The existence of NiAl is inevitable in all samples, despite the amount of Ni-based alloys in mixtures, or even the atomic percentage of nickel, where the appearance of Ni3Al depends only on increasing the amount of the Ni-based alloy to 50 % percent in mixtures. As regards the steel substrate, the microhardness of the interdiffusion zone of the substrate has been significantly enhanced. Results have shown that the microhardness of the different tested coatings is increased directly with the increment of Ni-based percentage in the coating mixture. The average porosity of the plasma sprayed coatings has proven to be within the normal range.
Studying the distribution of hardness values in friction drilled 7075 Al-alloy sheets at different conditions
Authors: Hamzawy N , Khedr M , Mahmoud T S , Ei-Mahallawi I , Khalifa T A 
Published: August 2021

Abstract
The thickness of sheet metal parts can be locally increased by friction drilling technology via forming of a hole with a bush by a special drilling tool. Here, a 7075 Al-alloy was drilled by friction using tool cone angles with values of 40, 45 and 50° under different feed rates (100, 200 and 315 mm/min) and rotational speeds (1000, 1250 and 1600 rpm). The present study investigates the hardness distribution in the thermally-formed bush and in the heat-affected zone around the bush. It was found that the hardness of the bush was slightly increased with increasing of the tool cone angle and reduction of the tool rotational speed. However, the hardness of the thermally-induced bush showed values lower than the parent metal. The hardness near the drilling surface was approximately 65±10 HV, while it recorded hardness values of 75±10 HV at 5 mm away from the drilling surface. In addition, the microstructure of the friction drilled specimens showed a very fine structure in the drilling zone due to crushing of the original structure during the friction drilling process.
Low thermal emissivity coating based on aluminium / acrylic composite coatings
Authors: Ateia E E , Metwaly M A , Tantawy H R 
Published: August 2021

Abstract
Low emissivity coatings were synthesized by using fine flake Aluminium (Al) powder as a filler within acrylic resin to from the desired composite coatings. In the current work, ball milling was applied to prepare Al with different shapes and sizes. The technical parameters of prepared Al powders with respect to the initial raw Al are characterized by scanning electron microscope (SEM), X-Ray diffraction (XRD), and Energy Dispersive X-Ray Analysis (EDX). Moreover, parameters that affect the emissivity of the coating was investigated; such as coating thickness, particle size, spin coating, ball milling time and the content of coated Al powder. The thermal signature is highly affected by the variation in Al content (5%, 20%, 25%, 35%, 40% and 60%) at different temperatures (50°C, 70°C, 90°C). The results indicate that the perfect percentage for the filler (Al) in the matrix within the range (35 wt. - 40 wt. %) and Al fine flake powder particle, which gives the lowest infrared emissivity of 0.385 μm and 0.412 μm for (3-5) μm, (8-12) μm, respectively.
Enhancement of carbon fiber/epoxy composite electrical, optical and thermal properties by using different types of nano-additives
Authors: Bassiouny L , Samir T , Abdallah S , Ashour H , Anwar A 
Published: August 2021

Abstract
Environmental space threats are becoming more critical as they affect the optical, thermal, and electrical properties of the reinforced fiber polymeric-based materials in spacecraft. Three different Nano-particles Alumina (Al2,O3), Multiwall Carbon Nanotubes (MWCNT), and Reduced Graphene Oxide (RGO) were added to the epoxy matrix and then reinforced by bidirectional carbon fiber plain to form carbon fiber/epoxy by hand lay-up using autoclave curing technique to make three different reinforced materials. In this paper, the electrical, optical, and thermal properties of the carbon fiber/Epoxy Nanocomposite were studied.
Fourier transform infrared (FTIR) was performed to evaluate the structural changes in the newly synthesized materials. The optical, thermal, and electrical properties were tested by UV-visible Spectroscopy, Photo-acoustic spectroscopy (PA), and Keithley 2635A respectively. The results showed an enhancement in the electrical, optical, and thermal properties of the epoxy matrix after the addition of Nano-particles.
The optical test showed that the neat epoxy and epoxy/Nano-particles absorption spectra were in the infrared range. The thermal test indicated that the three thermal parameters diffusivity, effusivity, and conductivity showed the best enhancement after the addition of MWCNTs. The electrical test pointed out that after the addition of Nano-particles, neat epoxy changed from an insulating material to a semi-conductive material.
Investigation of foamcrete mechanical and physical properties
Authors: Youssef T , Elsayed Y , Elsayed T A , Lawaty S M 
Published: August 2021

Abstract
Engineered Material Arresting Systems (EMAS) serve as a substitutional alternative/solution to airport runways when the Runway Safety Area (RSA) does not meet international Federal Aviation Administration (FAA) standards. The length of the runway can be shortened if an EMAS is installed on both ends of the runway. This paper provides experimental test results on foamcrete material used for such an important safety application. The objective of the paper is to present the required and measured properties of foamed concrete (density, compressive strength and water absorption) and results of an evaluation of a first phase of testing. In this study, a total of fourty eight mixes were conducted; yielding a range of densities, compressive strength(s) and water absorption characteristics that are: 554 to 1528 kg/m3, 1.1 to 21 MPa and 7.4 to 28.3 %, respectively. It is demonstrated herein – though the Analysis of Means statistical method – that foam volume is predominantly the main factor affecting the observed output characteristics. This is followed by Sand/Filler and Filler/Cement that yield marginal effect compare to the former foam volume ingredient.
Enhancing the propulsion characteristics of rockets by adding the energetic Nitro-hydroxyl-terminated polybutadiene (NHTPB) in the propellant compositions
Authors: Azazy A , Saleh A , Aly W F , Elbeih A , Hussein A K , Elshenawy T , Abdelhafiz M , Wafy T Z , Zaki M. G. , Ahmed H S 
Published: August 2021

Abstract
Replacing the inert binder by an energetic one could increase the specific impulse of the propellants and enhance the propulsion characteristics of rockets. In this study, Nitro-b
hydroxyl-terminated polybutadiene (NHTPB) was prepared by a simple method. The prepared NHTPB in addition to HTPB binder were characterized. FTIR spectra of both HTBP and NHTPB was determined and compared. The thermal behavior of the prepared NHTPB was studied using DSC technique at heating rate 5 degree/min. A composite propellant based on AP/NHTPB was prepared and the specific impulse was measured for AP/NHTPB using two inch motor. It was concluded that the energetic nitro-hydroxyl-terminated polybutadiene has a clear max. exothermic peak at 203 °C with heat release of 323 J/g. By comparing the results, the prepared propellant AP/NHTPB has specific impulse higher than the traditional AP/HTPB propellant. NHTPB is a promising binder for the application of rocket propellants and needs more tests for its approval.
Acoustic threat detection and direction finding system
Authors: Abdallah A , Tork H 
Published: August 2021

Abstract
In this paper, an acoustic threat detection system is investigated as preliminary study of one of the anti-terrorism systems. The proposed system is a prototype of acoustic threats detection, classification, and direction finding system. For this purpose, an experiment is performed to test the capability of a proposed warning system to perform the task accurately. The direction of the sound source is determined by means of two microphones. The angle to the acoustic threat is calculated based on time difference of arrival (TDOA). The limitations of the system are discussed and some possible solutions are introduced to improve the performance of the system.
Tactics Overview for Implementing High-Performance Computing on Embedded Platforms
Authors: Elshazly A , Elliethy A , Elshafey M A 
Published: August 2021

Abstract
Future space missions will rely on novel high-performance computing to support advanced intelligent on-board algorithms with substantial workloads that mandates firm real-time and power constraints requirements. Consequently, these advanced algorithms require significantly faster processing beyond the conventional space-grade central processing unit capabilities. Moreover, they require careful selection of the target embedded platform from a diverse set of available architectures along with several implementation tactics to map the algorithms to the target architecture to fully unlock its capabilities. In this paper, we present a study of different architectures and embedded computing platforms for the satellite on-board computers. Moreover, we present a comprehensive overview of recent implementation tactics such as source code mapping and transformations. Additionally, we highlight some optimization techniques such as partitioning and co-designing using hardware accelerators. Finally, we discuss several implementation analysis methodologies to derive optimized code implementations. The top ranked YOLO-v3, as a deep learning based object detection algorithm, is selected as a case study model to be optimized using OpenVINO toolkit. The experimental results show an improvement ratios up to 73%, 41%, and 34% in terms of frames per second, CPU utilization, and cache memory, respectively. The study presented in this paper aims to guide the researchers in the field of high performance embedded computing in terms of different hardware architectures along with several implementation tactics.
Modelling and simulation of two axes gimbal fuzzy PI stabilization system in the presence of feedback sensors noise
Authors: Fathi A , Kamel A M , Elfarouk A O , Elhalwagy Y 
Published: August 2021

Abstract
The missile guidance in terminal phase is an optimization problem as the miss distance should be minimized. The optimization of missile miss distance is highly affected by the missile seeker performance. Design of gimbal control system suffers always from feedback sensors noise which leads to system instability. In this paper, a promising design of the fuzzy PID controller for a missile seeker gimbal is proposed considering the feedback sensor noise with practical gyro transfer function calculated based on real experimental measurements utilizing MATLB system identification toolbox. Also, the mathematical model of two stabilized axes gimbal. Stabilization is achieved considering the missile motion parameters such as rates, torques and coupling between yaw and roll channels. A Matlab simulation is carried out for evaluating the proposed system modelling and to test the robustness of the fuzzy PID controller in the presence of feedback sensor noise. A comparative analysis with PI based controller is conducted to evaluate the performance of the proposed controller which presents sufficient enhancement to the missile gimbal stability parameters.
Performance comparison among popular implementations of H.264 encoders
Authors: El-Arsh H Y , Elliethy A S , Abdelaziz A M , Aly H A 
Published: August 2021

Abstract
Remote sensing videos captured by Unmanned Aerial Vehicle (UAV) air-born high-resolution cameras require an efficient compression scheme that preserves the details of the visual contents of the videos while reducing the total size of the data to be managed in real-time. This paper presents a detailed comparison between different open-source implementations for the H.264 video compression scheme. While the high-resolution videos allow analysts to extract more descriptive interpretations and draw more conclusive results, the increase in the consequent data size consumes more storage, resulting in more channel bandwidth, more power, and encounters an extra delay in transmission time. An efficient implementation of video compression can alleviate these large data size effects. In this paper, we analyze and compare the JM-encoder, the X264, the FFmpeg, and Cisco’s OpenH264 open-source implementations in terms of compression efficiency, video quality, and computational load. Moreover, we present the rate-distortion curves in terms of PSNR as a quality metric against the bit-rate for a combination of 20 videos with various resolutions and dynamic contents. Albeit H.64 is superseded by H.265, till now H.264 is used in more than 65% of video coding applications. For example, YouTube only allows H.264 for live streaming.
Modelling and transient response study of hydraulic servo actuator
Authors: Ibrahim E E , Elnady T , Saleh I , Hassan S 
Published: August 2021

Abstract
This paper presents a mathematical model of electro hydraulic servo system (EHS) using two-stage electrohydraulic servovalve (EHSV), by the aim of Matlab-simulink-simscape multibody to predict the flow characteristics (pressure/flow rate) with changing the parametric configuration of (EHSV), these parameters could be used to estimate the error at different operating conditions. It includes establishing mathematical model, controller model and validating the performance of the (EHSV) by experimental result of published work using the data of servovalve labelled B.31.210.12.1000.U2V (mechanical feedback) manufactured by PPT - Trstenik. The effect of changing servovalve orifice diameter (0.25, 0.30, and 0.35) mm, show that increasing the orifice diameter of the servovalve leads to increase the transient time but decrease the system overshoot. The pressure behaviour is plotted and shows that increasing the orifice diameter leads to increasing the pressure inside the system as to reach the relieve pressure.
Formation configuration of unmanned cooperative quadrotors via PID tuning approaches
Authors: Mahfouz M , Taiomour A , Ashry M M , Elnashar G 
Published: August 2021

Abstract
Formation configuration is one of the major intrinsic strategies used in cooperative Unmanned Air Vehicles field. In this paper, Backstepping-PID control technique for cooperative quadrotors unmanned aerial vehicles are developed to solve the formation problem. The proposed controller is divided into couple of parts working together. Backstepping controller is used to stabilize the position control as a higher controller. Simultaneously, PID controller receives the desired position to stabilize the attitude control as a lower controller to track the desired planning trajectories. The main contribution of this paper is using Fraction Order Approach, and Local Optimal Approach to refine the PID lower controller gains. The tunning of the PID gains through the proposed PID tuning approaches guarantee the stabilization of the attitude control for all the team members. Simulation results present the success of the proposed PID tuning approaches in solving the formation problem for cooperative unmanned quadrotors tracking a desired path. Moreover, the simulation results present the ability of the proposed approaches to handle disturbance rejection and noise attenuation while preserving the stability of the system.
Impact of nozzle profile on ballistic performance and structural loads
Authors: Saleh M , Saleh S , Zayed A , Ahmed M Y M 
Published: August 2021

Abstract
A nozzle is a device that is designed to regulate the direction and characteristics of the combustion gas products of jet engines. So, the nozzle performance has a significant impact on the mission achievement. This paper is concerned with the internal ballistics of the nozzle aiming to estimate pressure and thermal loads on its walls. Computational fluid dynamics is applied to analyse the effect of changing nozzle internal profile on the resulting thrust, flow energy losses, and nozzle wall structure. Area ratios at the inlet, critical, and exit sections are considered as constraints for the examined design. Two different sets with 4 different profiles for each are investigated. The results show thrust, entropy losses across the nozzle and the static pressure and temperature at nozzle wall. Bell shape profiles produce better performance compared to other profiles. Changing the internal profile of the nozzle causes significant change in pressure and temperature loads acting on nozzle wall structure.
Parametric study of solid propellant slotted grain
Authors: El-Naggar M , Belal H , Abdalla H M 
Published: August 2021

Abstract
One of the goals in solid rocket motor design is to have as large volumetric loading as possible keeping the basic requirements unaffected. Slotted grain can achieve this goal as it has the advantages of sliver-free and no stress-concentration regions that occur in other internal burning grains as star grain and wagon wheel grain. It has the disadvantage of exposing the motor wall to hot gases. In this paper, the geometry of slotted grain is discussed and the effect of design parameters (e.g., number of slots, dimensions of the slot, etc.) of slotted grain on grain burn back is explained. Also, a comparison between results and experimental data is performed.
Application of the level set method in solid propellant grain burnback with dogbone grain as a case study
Authors: Adel H , Belal H 
Published: August 2021

Abstract
Solid propellant grain burnback is a crucial step internal ballistic module. There are different methods to predict grain burnback; the oldest method is the drafting technique where the burning surface is tracked using manual drawing applying surface regression rules. Then there is the analytical method, where a geometric analysis of the surface is performed and analytical expressions for the burning surface segments are derived. These expressions are evaluated at different values of burnt distance to find the evolution of burning surface and port areas with time. A level set method is a different approach which, in some aspects, may be considered a drafting technique where the burning surface segments are tracked. From another point of view, it is a numerical method that tracks the burning surface with no need of trying to derive analytical expressions for burning segments. Dogbone grain is known for its structural superiority; however, researches dealing with dogbone grain design parameters are scarce. In this paper, the level set method is introduced and the main steps for its implementation are elaborated. Validation of the level set method is performed against the drafting technique using CAD and analytical expressions for the well-known star grain. Finally, dogbone grain geometry with different configurations is introduced and a parametric study for the governing parameters that affect dogbone grain burnback is performed.
Experimental investigation of recirculation zone characteristics of a pre-filming airblast injector
Authors: Darwish N , Shanmugadas K P , Chakravarthy S R 
Published: August 2021

Abstract
The toroidal flow at the recirculation zone has a vital role in combustion process as it helps in mixing hot combustion products with incoming fresh air and fuel which increases combustion efficiency. In the present work, characteristics of recirculation zone are investigated using a pre-filming airblast injector. Particle Image Velocimetry is used to characterize the swirl flow field generated by the airblast injector. Moreover, olive oil is used as a tracer to be captured by a high-speed camera. Different flow rates are investigated in order for finding out the effect of varying flow rates on the characteristics of the recirculation zone. Results for recirculation zone shape, velocity field and shear strength at the primary zone of combustion are represented. Additionally, results show that recirculation zone is almost symmetrical with increasing trend in shear strength with increasing flow rates.