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An algebraic approach for system with multiple relative motions
Rashad A. Abdel-Baky,Basma H. Shafee 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3
We present geometry and kinematic expressions for a kinematical system of multiple relative motions and containing a differentiable line-system using dual vector-matrix methods. This procedure enables us to obtain a generalization of the well-known three-pole theorem. In particular, for one-parameter spatial motions, the pitch of the helical motion is the translation multiplied by the tangent of the screw motion rotation . As a result, theoretical expressions for the direction of a line complex were revealed and used to examine a ruled surface traced out by a fixed line in a rigid body undergoing a screw motion of constant pitch.
Wideband Low-Reflection Transmission Lines for Bare Chip on Multilayer PCB
Rashad Ramzan,Jonas Fritzin,Jerzy Dabrowski,Christer Svensson 한국전자통신연구원 2011 ETRI Journal Vol.33 No.3
The pad pitch of modern radio frequency integrated circuits is in the order of few tens of micrometers. Connecting a large number of high-speed I/Os to the outside world with good signal fidelity at low cost is an extremely challenging task. To cope with this requirement, we need reflection-free transmission lines from an on-chip pad to on-board SMA connectors. Such a transmission line is very hard to design due to the difference in on-chip and on-board feature size and the requirement for extremely large bandwidth. In this paper, we propose the use of narrow tracks close to chip and wide tracks away from the chip. This narrow-to-wide transition in width results in impedance discontinuity. A step change in substrate thickness is utilized to cancel the effect of the width discontinuity, thus achieving a reflection-free microstrip. To verify the concept, several microstrips were designed on multilayer FR4 PCB without any additional manufacturing steps. The TDR measurements reveal that the impedance variation is less than 3 ohm for 50 ohm microstrip and S11 better than –9 dB for the frequency range 1 GHz to 6 GHz when the width changes from 165 um to 940 um, and substrate thickness changes from 100 um to 500 um.
The optimal system for series systems with warm standby components and a repairable service station
Rashad, A.M.,El-Sherbeny, M.S.,Gharieb, D.M. The Korean Reliability Society 2010 International Journal of Reliability and Applicati Vol.11 No.2
This paper deals with the reliability and availability characteristics of three different series system configurations with warm standby components and a repairable service station. The failure time of the primary and warm standby are assumed to be exponentially distributed with parameters ${\lambda}$ and ${\alpha}$ respectively. The repair time distribution of each server is also exponentially distributed with parameter ${\mu}$. The breakdown time and the repair time of the service station are also assumed exponentially distributed with parameters ${\gamma}$ and ${\beta}$ respectively. We derive the reliability dependent on time, availability dependent on time, the mean time to failure, $MTTF_i$, and the steady-state availability $A_i$(${\infty}$) for three configurations and perform comparisons. Comparisons are made for specific values of distribution parameters and of the cost of the components. The three configurations are ranked based on: $MTTF_i$, $A_i$(${\infty}$), and $C_i/B_i$ where $B_i$ is either $MTTF_i$ or $A_i$(${\infty}$).
Public Key Encryption with Equality Test for Heterogeneous Systems in Cloud Computing
( Rashad Elhabob ),( Yanan Zhao ),( Iva Sella ),( Hu Xiong ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.9
Cloud computing provides a broad range of services like operating systems, hardware, software and resources. Availability of these services encourages data owners to outsource their intensive computations and massive data to the cloud. However, considering the untrusted nature of cloud server, it is essential to encrypt the data before outsourcing it to the cloud. Unfortunately, this leads to a challenge when it comes to providing search functionality for encrypted data located in the cloud. To address this challenge, this paper presents a public key encryption with equality test for heterogeneous systems (PKE-ET-HS). The PKE-ET-HS scheme simulates certificateless public encryption with equality test (CLE-ET) with the identity-based encryption with equality test (IBE-ET). This scheme provides the authorized cloud server the right to actuate the equivalence of two messages having their encryptions performed under heterogeneous systems. Basing on the random oracle model, we construct the security of our proposed scheme under the bilinear Diffie-Hellman (BDH) assumption. Eventually, we evaluate the size of storage, computation complexities, and properties with other related works and illustrations indicate good performance from our scheme.
A NEW CONSTRUCTION OF TIMELIKE RULED SURFACES WITH CONSTANT DISTELI-AXIS
( Rashad A. Abdel-baky ),( Yasin Ünlütürk ) 호남수학회 2020 호남수학학술지 Vol.42 No.3
In this study, we construct timelike ruled surfaces whose Disteli-axis is constant in Minkowski 3-space □. Then we attain a general system characterizing these surfaces, and also give necessary and sufficient conditions for a timelike ruled surface to get a constant Disteli-axis.
Rashad, M.,Tekin, H.O.,Zakaly, Hesham MH.,Pyshkina, Mariia,Issa, Shams A.M.,Susoy, G. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.9
Magnesium oxide (MgO) and Zinc oxide (ZnO) nanoparticles (NPs) have been successfully synthesized by solid-solid reaction method. The structural properties of ZnO and MgO NPs were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results indicated a formation of pure MgO and ZnO NPs. The mean diameter values of the agglomerated particles were around to be 70 and 50 nm for MgO and ZnO NPs, respectively using SEM analysis. Further, a wide-range of nuclear radiation shielding investigation for gamma-ray and fast neutrons have been studied for Magnesium oxide (MgO) and Zinc oxide (ZnO) samples. FLUKA and Microshield codes have been employed for the determination of mass attenuation coefficients (μ<sub>m</sub>) and transmission factors (TF) of Magnesium oxide (MgO) and Zinc oxide (ZnO) samples. The calculated values for mass attenuation coefficients (μ<sub>m</sub>) were utilized to determine other vital shielding properties against gamma-ray radiation. Moreover, the results showed that Zinc oxide (ZnO) nanoparticles with the lowest diameter value as 50 nm had a satisfactory capacity in nuclear radiation shielding.
Mustafa Rashad,Abdo Ali,Siam Jamal,Küçükay Ferit 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.6
The increasing demand for spontaneity, comfort, and efficiency leads to the increasing complexity of dual-clutch transmissions and their shift controls. Friction modeling of piston seals plays an essential role in achieving a better understanding of the determinant factors of energy losses and, consequently, the realization of more efficient transmission hydraulic actuators. This paper studies the performance of a dual-clutch transmission during the gear-shifting process of a vehicle power train model. The Modified Generalized Maxwell-Slip friction model with Genetic Algorithm (MGMS-GA) parameters identification is used to include the effect of seal types. The gear shift comfort analysis and evaluation, with four different seal types, has been performed based on objectification. Simulations with O-Ring, D-Ring, Bonded, and Total Control System - Polytetrafluoroethylene piston seals were performed to show the validity of the model in practical scenarios. The study shows the superiority of the MGMS-GA in representing the experimental data and enhancing gearshift control and comfort. Moreover, it showed that the Total Control System-Polytetrafluoroethylene piston seal presented the highest performance among all seal types.
Alsanosy, Rashad Mohammed Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16
Background: Shammah is a traditional form of chewing tobacco [smokeless tobacco, (ST)] that is commonly used in the Middle East especially in Saudi Arabia (KSA), Yemen and Sudan. The Substance Abuse Research Centre (SARC) at Jazan University noted that no adequate research and information on the prevalence of shammah use in the province of Jazan, and KSA as well, has been provided in the scientific literature. Materials and Methods: An intensive systematic review of online databases was performed, including AMED (The Allied and Complementary Medicine Database), Biological Abstracts, Cochrane Collection Plus, Dentistry and Oral Sciences Source, E-Journals Database, EBSCO Discovery Service, MEDLINE, PEMSoft, PEP Archive, PsycARTICLES, scopus, Sciencedirect and Google Scholar. Results: Shammah is a mixture of powdered tobacco, lime, ash, black pepper, oils and flavorings. ST in KSA is placed in the buccal or lower labial vestibule of the mouth. The user (or dipper) spits out insoluble debris. The importation of ST products is prohibited in KSA. Accessible information on legislative action to control the use of ST in KSA appeared in 1990. The actual percentage use may be higher, than reported since shammah is illegal in KSA and there may be some reluctance to admit to its use. Conclusions: This review paper is an initial step in a funded research project by SARC to understand the pattern of use of shammah and provide adequate epidemiological data. One goal of this review is to generate further data for public health education.