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Dropwise condensation heat transfer enhancement on surfaces micro/nano structured by a two-step electrodeposition process

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Journal of Central South University 2019年第5期26卷 1065-1076页

作者： hamid Reza TALESH BAHRAMI Alireza AZIZI hamid saffari School of Mechanical Engineering Iran University of Science and Technology

Condensation is an important regime of heat transfer which has wide applications in different industries such as power plants,heating,ventilating and air conditioning,and *** occurs in two different modes including filmwise (FWC) and dropwise (DWC) *** occurring on hydrophobic and superhydrophobic surfaces has a much higher heat transfer capacity than ***,wide investigations have been done to produce DWC in recent *** surfaces have micro/nano structures with low surface *** this study,a two-step electrodeposition process is used to produce micro/nano structures on copper *** surface energy of specimens is reduced by a self-assembled monolayer using ethanol and 1-octadecanethiol *** results show that there is an optimum condition for electrodeposition *** example,a surface prepared by 2000 s step time has 5 times greater heat transfer than FWC while a surface with 4000 s step time has nearly the same heat transfer as *** surfaces of the fabricated specimens are examined using XRD and SEM *** SEM analyses of the surfaces show that there are some micro-structures on the surfaces and the surface porosities are reduced by increasing the second step electrodeposition time.

关键词： dropwise condensation heat transfer electrodeposition micro/nano structure porosity

Numerical analysis on forced convection enhancement in an annulus using porous ribs and nanoparticle addition to base fluid

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Journal of Central South University 2019年第5期26卷 1089-1098页

作者： Majid SIAVASHI hamid Reza TALESH BAHRAMI Ehsan AMINIAN hamid saffari School of Mechanical Engineering Iran University of Science and Technology

Miniaturization of electronic equipment has forced researchers to devise more effective methods for dissipating the generated heat in these *** this study,two methods,including porous media inserting and adding nanoparticles to the base fluid,are used to improve heat transfer in an annulus heated on both *** study porous media insert,porous ribs are used on the outer and inner walls *** results show that when porous ribs are placed on the outer wall,although the heat transfer enhances,the pressure drop increment is so considerable that performance number (the ratio of heat transfer enhancement pressure increment,PN) is less than unity for all porous rib heights and porous media permeabilities that are *** the other hand,the PN of cases where porous ribs were placed on the inner wall depends on the Darcy number (Da).For example,for ribs with Da=0.1 and Da=0.0001,the maximum performance number,PN=4,occurs at the porous ribs height to hydraulic diameter ratios H/Dh=1 and H/Dh=*** these conditions,heat transfer is enhanced by two orders of *** is found that adding 5% nanoparticles to the base fluid in the two aforementioned cases improves the Nusselt number and PN by 10%–40%.

关键词： nanofluid porous media annulus heat transfer enhancement internal flow

Thermodynamic Analysis of Series and Parallel Flow Water/Lithium Bromide Double Effect Absorption System with Two Condensers

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材料科学与工程（中英文B版） 2011年第2期1卷 206-217页

作者： Saeed Sedigh hamid saffari LNG research laboratory School of Mechanical Engineering Iran University of Science and TechnologyIran

Thermodynamic Analysis of Double Effect Absorption System along with Boiler and Cooling Tower

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Journal of Environmental Science and Engineering(A) 2012年第2期1卷 261-270页

作者： Saeed Sedigh hamid saffari hamidreza Taleshbahrami Liquefied Natural Gas Research Laboratory School of Mechanical Engineering lran University of Science and Technology NarmakTehran 16846 lran

Many researchers have studied single and double effect absorption cycles based on first and second lows of thermodynamics But so far the relation of different parameters inside these cycles to the second law of thermodynamics in boiler and cooling tower has not been investigated. In this paper, a system comprised of a series flow double effect water-Lithium bromide absorption chiller, a boiler and a cooling tower is studied based on the first and second laws of thermodynamics, and also exergy analysis is investigated. For this purpose, mass and energy conservation laws governing the system are written, and coefficient of performance of the system, exergy destruction （loss） of each component and exergy efficiency have been calculated.

关键词： Absorption chiller thermodynamic analysis cooling tower.

Automatic recognition of sonar targets using feature selection in micro-Doppler signature

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Defence Technology（防务技术） 2023年第2期20卷 58-71页

作者： Abbas saffari Seyed-hamid Zahiri Mohammad Khishe Department of Electrical Engineering University of BirjandBirjandIran Department of Electrical Engineering Imam Khomeini Marine Science UniversityNowshahrIran

Currently,the use of intelligent systems for the automatic recognition of targets in the fields of defence and military has increased *** primary advantage of these systems is that they do not need human participation in target recognition *** paper uses the particle swarm optimization(PSO)algorithm to select the optimal features in the micro-Doppler signature of sonar *** microDoppler effect is referred to amplitude/phase modulation on the received signal by rotating parts of a target such as *** different targets'geometric and physical properties are not the same,their micro-Doppler signature is *** Inconsistency can be considered a practical issue(especially in the frequency domain)for sonar target *** using 128-point fast Fourier transform(FFT)for the feature extraction step,not all extracted features contain helpful *** a result,PSO selects the most optimum and valuable *** evaluate the micro-Doppler signature of sonar targets and the effect of feature selection on sonar target recognition,the simplest and most popular machine learning algorithm,k-nearest neighbor(k-NN),is used,which is called k-PSO in this paper because of the use of PSO for feature *** parameters measured are the correct recognition rate,reliability rate,and processing *** simulation results show that k-PSO achieved a 100%correct recognition rate and reliability rate at 19.35 s when using simulated data at a 15 dB signal-tonoise ratio(SNR)angle of 40°.Also,for the experimental dataset obtained from the cavitation tunnel,the correct recognition rate is 98.26%,and the reliability rate is 99.69%at ***,the k-PSO has an encouraging performance in automatically recognizing sonar targets when using experimental datasets and for real-world use.

关键词： Micro-Doppler signature Automatic recognition Feature selection k-NN PSO

Mitochondrial DNA sequence diversity in three ethnic populations from the South-west Iran:a preliminary study

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Frontiers in Biology 2011年第5期6卷 422-432页

作者： Elham DAVOUDI-DEHAGHANI Ali Mohammad FOROUGHMAND Babak saffari Massoud HOUSHMAND hamid GALEHDARI Mehdi SHAFA SHARIAT PANAHI Majid YAVARIAN Mohammad Hossein SANATI Somayeh TORFI Department of Genetics Shahid Chamran UniversityAhvaz 61357-43337Iran Medical Genetics Department Tehran University of Medical SciencesTehran 14155-6447Iran Human Genetic Research Group Iranian Academic Center for EducationCulture&Research(ACECR)Fars Province BranchShiraz 71347Iran National Institute for Genetic Engineering and Biotechnology Tehran 14155-6343Iran Hematology Research Center School of MedicineShiraz University of Medical SciencesShiraz 71937Iran

To investigate the genetic structure of human populations in the South-west region of Iran,mitochondrial first hypervariable DNA sequences were obtained from 50 individuals representing three different ethnic groups from Khuzestan *** groups were Shushtari Persians and Chahar Lang Bakhtiyaries from Indo-Europeanspeaking populations and Bani Torof Arabs from Semitic-speaking linguistic *** analysis of mtDNA data showed high similarity of Chahar Lang Bakhtiyaries with other Iranian Indo-European-speaking populations while Shushtaries and Bani Torofs had a closer affinity with Semitic-speaking groups rather than to other Iranian *** relationship of Chahar Lang Bakhtiyaries and Bani Torof Arabs with their neighbor populations can be explained by linguistic and geographic ***,the greater similarity of Shushtari Persians with West Asian Arabs is probably according to high gene flow between *** article represents a preliminary study of three major ethnic groups of South-west Iran which investigates the potential genetic substructure of the region.

关键词： diversity mitochondrial DNA first hypervariable sequence Iran genetic structure population