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Journal of Semiconductors 2015年第5期36卷 61-65页

作者： hamed Ghodsi Hassan Kaatuzian Photonics Research Laboratory(P.R.L.) Electrical Engineering DepartmentAmir Kabir University of Technology

In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 μm-SiGe-BiCmOS process, we propose some slight modifications in the bipolar section of the SiGe device physical design. Comparison of our new proposed device and the previously reported device is done by SILVACO TCAD software simulation and we have used previous experimentally reported data to confirm our software simulations. Our proposed modifications in device structural design show a present device responsivity improvement of about 10% from 1 to 1.1 A/W while the bandwidth improvement is about 218 GHz. The minimum noise equivalent power at detector output is increased by about 14.3% and finally power consumption per pixel at the maximum responsivity is decreased by about 5%.

关键词： terahertz SiGe HBT physical structure direct conversion detector

Effects of Zr additions on structure and tensile properties of an Al-4.5Cu-0.3mg-0.05Ti(wt.%) alloy

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China Foundry 2022年第1期19卷 9-16页

作者： hamed Kamali Erfan Kamali massoud Emamy School of metallurgy and materials Engineering College of EngineeringUniversity of TehranP.O.Box 11155-4563TehranIran Faculty of materials Engineering Sahand University of TechnologyP.O.Box 51335-1996TabrizIran

The effects of different Zr additions(0.05wt.%-0.5wt.%)on the structure and tensile properties of an Al-4.5Cu-0.3mg-0.05Ti(wt.%)alloy solidified under a high cooling rate(18℃·s^(-1)),in as-cast and T6 heat-treated conditions were *** as-cast structure of the alloy consists of equiaxed grains ofα-Al with an average size of 64μm which is unaffected by the Zr additions,indicating the ineffectiveness of Zr in the grain refinement of the *** electron microscopy,along with X-ray diffraction analysis revealed the presence of elongatedθ-Al2Cu at the grain boundaries;in addition,coarse Al3Zr particles exist in the intergranular regions of the 0.5wt.%Zr-containing *** the T6 heat treatment,the elongatedθparticles were fragmented;however,the coarse Al3Zr particles remained unchanged in the ***,the formation of fineβ’-Al3Zr andθ’’-Al3Cu/θ’-Al2Cu phases during T6 heat treatment was revealed by transmission electron *** results of the tensile tests showed that the Zr additions increase the strength of the alloy in both as-cast and T6 heat-treated conditions,but reduce its elongation,especially with 0.5wt.%Zr *** 0.3wt.%Zr-added alloy in the T6 heat-treated condition has the highest quality index value(249 mPa).Fractography of the fracture surfaces of the alloys revealed ductile fracture mode including dimples and cracked intermetallic phases in both conditions.

关键词： Al-Cu-mg alloys casting T6 heat treatment structure precipitation hardening tensile properties fractography

Ant Colony Optimization for multi-Objective multicast Routing

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Computers, materials & Continua 2020年第6期63卷 1159-1173页

作者： Ahmed Y.hamed monagi H.Alkinani m.R.Hassan Department of Computer Science Faculty of Computers and InformationSohag UniversitySohag82524Egypt Department of Computer Science and Artificial Intelligence College of Computer Science and EngineeringUniversity of JeddahJeddah21959Saudi Arabia Department of mathematics and Computer Science Faculty of ScienceAswan UniversityAswan81528Egypt

In the distributed networks,many applications send information from a source node to multiple destination *** support these applications requirements,the paper presents a multi-objective algorithm based on ant colonies to construct a multicast tree for data transmission in a computer *** proposed algorithm simultaneously optimizes total weight(cost,delay and hop)of the multicast *** results prove the proposed algorithm outperforms a recently published multi-objective multicast Algorithm specially designed for solving the multicast routing ***,it is able to find a better solution with fast convergence speed and high reliability.

关键词： multimedia communication multicast routing multicast tree quality of service ant colony

A Genetic Algorithm to Solve Capacity Assignment Problem in a Flow Network

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Computers, materials & Continua 2020年第9期64卷 1579-1586页

Computer networks and power transmission networks are treated as capacitated flow networks.A capacitated flow network may partially fail due to ***,the capacity of each edge should be optimally assigned to face critical situations-i.e.,to keep the network functioning normally in the case of failure at one or more *** robust design problem(RDP)in a capacitated flow network is to search for the minimum capacity assignment of each edge such that the network still survived even under the edge’s *** RDP is known as ***,capacity assignment problem subject to system reliability and total capacity constraints is studied in this *** problem is formulated mathematically,and a genetic algorithm is proposed to determine the optimal *** optimal solution found by the proposed algorithm is characterized by maximum reliability and minimum total *** numerical examples are presented to illustrate the efficiency of the proposed approach.

关键词： Flow network capacity assignment network reliability genetic algorithms

Nonlinear study of the dynamic behavior of a string-beam coupled system under combined excitations

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Acta mechanica Sinica 2011年第6期27卷 1034-1051页

作者： Y.S. hamed m. Sayed D.-X. Cao W. Zhang Department of Engineering mathematics Faculty of Electronic Engineering Menouf 32952 Egypt College of mechanical Engineering Beijing University of Technology 100022 Beijing China Department of mathematics and Statistics Faculty of Science Taif University Taif E1-Haweiah EO. Box 888 Zip Code 21974 Kingdom of Saudi Arabia （KSA）

In this paper,the nonlinear dynamic behavior of a string-beam coupled system subjected to external,parametric and tuned excitations is *** governing equations of motion are obtained for the nonlinear transverse vibrations of the string-beam coupled system which are described by a set of ordinary differential equations with two degrees of *** case of 1：1 internal resonance between the modes of the beam and string,and the primary and combined resonance for the beam is *** method of multiple scales is utilized to analyze the nonlinear responses of the string-beam coupled system and obtain approximate solutions up to and including the second-order *** resonance cases are extracted and *** of the system is studied using frequency response equations and the phase-plane *** solutions are carried out and the results are presented graphically and *** effects of the different parameters on both response and stability of the system are *** reported results are compared to the available published work.

关键词： 1:1 internal resonance - String-beam - multiple scales Chaotic response Stability

High Gain Predictions for Ni-Like Ta Ions

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Chinese Physics Letters 2013年第11期30卷 80-83页

作者： Wessameldin S.Abdelaziz A.A.Farrag H.m.hamed mai E.Ahmed National Institute of Laser Enhanced Sciences Cairo UniversityGizaEgypt Faculty of Science Cairo UniversityGizaEgypt Environmental Affairs Agency(EEAA) Egypt

Atomic structure data and effective collision strengths for 1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10) and 54 fine-structure levels are contained in the configurations 1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(9)4l(l=s,p,d,f)for the nickel-like Ta *** data are used in the determination of the reduced population for the 55 fine structure levels over a wide range of electron densities(from 10^(21) to 10^(23))and at various electron plasma *** gain coefficients for those transitions with a positive population inversion factor are determined and plotted against the electron density.

关键词： density nickel structure

Grasshopper KUWAHARA and Gradient Boosting Tree for Optimal Features Classifications

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Computers, materials & Continua 2022年第8期72卷 3985-3997页

作者： Rabab hamed m.Aly Aziza I.Hussein Kamel H.Rahouma The Higher Institute for management and Information Technology Minya61768Egypt Department of Electrical and Computer Engineering Effat UniversityJeddahKSA Electrical Engineering Department Faculty of EngineeringMinia UniversityMinia6111Egypt

This paper aims to design an optimizer followed by a Kawahara filter for optimal classification and prediction of employees’*** algorithm starts by processing data by a modified K-means technique as a hierarchical clustering method to quickly obtain the best features of employees to reach their best *** work of this paper consists of two *** first part is based on collecting data of employees to calculate and illustrate the performance of each *** second part is based on the classification and prediction techniques of the employee *** model is designed to help companies in their decisions about the employees’*** classification and prediction algorithms use the Gradient Boosting Tree classifier to classify and predict the *** of the paper give the percentage of employees which are expected to leave the company after predicting their performance for the coming *** also show that the Grasshopper Optimization,followed by“KF”with the Gradient Boosting Tree as classifier and predictor,is characterized by a high *** proposed algorithm is compared with other known techniques where our results are fund to be superior.

关键词： metaheuristic algorithm KUWAHARA filter Grasshopper optimization algorithm and Gradient boosting tree

Rapid synthesis of moSi_2-Si_3N_4 nanocomposite via reaction milling of Si and mo powder mixture

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International Journal of minerals,metallurgy and materials 2013年第11期20卷 1107-1114页

作者： majid Abdellahi Alireza Amereh hamed Bahmanpou Behzad Sharafati Department of materials Engineering Islamic Azad UniversityNajafabad Branch Department of materials Engineering Islamic Azad UniversitySaveh Branch Department of Chemical Engineering and materials Science University of California

The nanocomposite of moSi2-SiaN4 （molybdenum disilicide-silicon nitride） was synthesized by reaction milling of the mo and Si powder mixture. Changing the processing parameters led to the formation of different products such as a- and B-moSi2, SiaN4, mo2N, and m05Si3 at various milling times. A thermodynamic appraisal showed that the milling of moa2Siss powder mixture was associated with highly exothermic mechanically induced self-sustaining reaction （mSR） between mo and Si. The mSR took place around 5 h of milling led to the formation of a-moSi2 and the reaction between Si and N2 to produce Si3N4 under a nitrogen pressure of 1 mPa. By increasing the nitrogen pressure to 5 mPa, more heat is released, resulting in the dissociation of Si3N4 and the transformation of a-moSi2 to β-moSi2. Heat treatment was also performed on the milled samples and led to the formation of mo2N and the transformation of a-moSi2 to β-moSi2 at the milling times of 10 and 40 h, respectively.

关键词： nanocomposites reaction milling molybdenum disilicide silicon nitride powders

Experimental investigation on the effects of microwave irradiation on kimberlite and granite rocks

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Journal of Rock mechanics and Geotechnical Engineering 2021年第2期13卷 267-274页

作者： Samir m.Deyab hamed Rafezi Ferri Hassani mehrdad Kermani Agus P.Sasmito Department of mining and materials Engineering McGill UniversityMontrealCanada

This study is a part of an overall research project on the effects of microwave(mW)irradiation on rocks for assisted rock breaking systems as well as mineral processing at mcGill *** the first time,this paper highlights a comprehensive investigation on the effects of microwave irradiation on Canadian *** contribution to the continuous rock excavation and rock weakening effect prior to implementation of mechanical techniques was *** different kimberlite rocks,*** kimberlite(VK)and hypabyssal kimberlite(HK),and granite samples were *** important physical properties of the rock samples were measured including rock quality designation(RQD),specific gravity,porosity,and specific heat *** samples were treated for various exposure times using a multi-mode mWunit at different power levels ranging from 2 kW to 15 *** effect of mW irradiation on rock samples was *** results indicate that the mechanical properties including unconfined compressive strength(UCS)and Brazilian tensile strength(BTS)were significantly dropped as a result of ***,the effect on rock abrasivity using the Cerchar abrasivity index(CAI)has also been discussed.

关键词： microwave irradiation Kimberlite Rock excavation Rock strength Abrasivity

mineralogy and Geochemistry of Uraniferous Sandstones in Fault Zone,Wadi El Sahu Area,Southwestern Sinai,Egypt:Implications for Provenance,Weathering and Tectonic Setting

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Acta Geologica Sinica(English Edition) 2021年第3期95卷 830-845页

作者： Osama R.SALLAm hamed ImIRA Amira m.El TOHAmY Abd Elhadi AABBAS Nuclear materials Authority El-Maadi Cairo P.O.Box:530Egypt

Paleozoic rocks in the Wadi El Sahu area are affected by many major faults in different directions.A reverse fault trending NE-SW is exposed for about 300 m of its length as it cuts through the Abu Hamata and Adedia formations on the south side of Wadi El Sahu.A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passed through the fault plain and the surrounding fractures,forming mineralized and radioactive *** mineralized zone thickness ranges from 60 cm to 200 cm along the fault *** rocks were analyzed radiometrically using a portable gamma-ray spectrometer,chemically by employing ICP-ES and ICP-mS,as well as mineralogically by both binocular and Environmental Scanning Electron *** content was also determined by fire *** and U contents reached up to 2682 and 1216 ppm,*** investigations indicated the presence of uraninite,torbernite,autunite,sklodowskite,kasolite as uranium minerals,thorite as a thorium mineral,monazite,allanite and xenotime as REE-bearing minerals,zircon and columbite as accessory minerals,gold and nickel as precious and base metals,in addition to cassiterite,chalcopyrite,chalcocite and *** REE and U contents are attributed to the circulation of epigenetic U and REE-bearing hydrothermal solutions along the fault plain and its surrounding *** alteration processes could then be confirmed by the presence of the m-type tetrad effect in the REE-patterns of the ferruginous *** non-chondritic ratio of Nb/Ta,Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad *** Ce and Eu anomaly with unusual REE-patterns was represented by the presence of conjugated m-W tetrad effects,indicating either the dual effect of hydrothermal solutions or groundwater with *** results clarify that the tetrad-effects could be used as evidence for the environment of deposition and as an indication for gold minerali

关键词： uranium gold RREs tetrad effect