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Lead-free piezoelectric materials and ultrasonic transducers for medical imaging

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Journal of Advanced Dielectrics 2015年第2期5卷 14-28页

作者： Elaheh Taghaddos Mehdi Hejazi ahmad safari Glenn Howatt Electroceramics Laboratories Department of Materials Science and EngineeringRutgers University607 Taylor RoadPiscatawayNew Jersey 08854USA

Piezoelectric materials have been vastly used in ultrasonic transducers for medical *** this paper,firstly,the most promising lead-free compositions with perovskite structure for medical imaging applications have been *** electromechanical properties of various lead-free ceramics,composites,and single crystals based on barium titanate,bismuth sodium titanate,potassium sodium niobate,and lithium niobate are ***,fundamental principles and design considerations of ultrasonic transducers are briefly ***,recent developments in lead-free ultrasonic probes are discussed and their acoustic performance is compared to lead-based *** transducers with different beam focusing methods such as lens focusing and mechanical shaping are ***,acoustic characteristics of lead-free probes including the pulse-echo results as well as their imaging capabilities for various applications such as phantom imaging,in vitro intravascular ultrasound imaging of swine aorta,and in vivo or ex vivo imaging of human eyes and skin are reviewed.

关键词： Lead-free piezoelectric ultrasonic transducers medical imaging.

Non-catalytic conversion of wheat straw,walnut shell and almond shell into hydrogen rich gas in supercritical water media

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Chinese Journal of Chemical Engineering 2016年第8期24卷 1097-1103页

作者： Farid safari Mohammad Salimi ahmad Tavasoli Abtin Ataei Department of Energy Engineering Science and Research Branch Islamic Azad University School of Chemistry College of science University of Tehran

Agricultural wastes as lignocellulosic biomasses are known as the major resources of bioenergy. These valuable resources can be converted into useful environmental friendly fuels and chemicals. Wheat straw, walnut shell and almond shell are the main agricultural wastes in Kurdistan province, Iran. This study investigates the hydrogen-rich gas production via gasification of these biomasses in supercritical water media. Experiments were performed first, in the base case condition using a stainless steel batch micro reactor system. Then, the effect of reaction time on the total gas yield and yield of hydrogen, were investigated. It was seen that the total gas yields and gasification efficiencies increased by increasing the reaction time to 30 min and then the total gas yield was approximately remained constant. Among three used feed stocks, wheat straw with higher amount of cellulose and lower amount of lignin had the highest total gas and hydrogen yields in shorter reaction *** maximum hydrogen yields of 7.25, 4.1 and 4.63 mmol per gram of wheat straw, almond shell and walnut shell occurred at 10, 15 and 20 min of reaction time, respectively.

关键词： Hydrogen Biomass Gasification Supercritical water media

A Study on Flame Forming of Bowl Shaped Surface with Various Spiral Irradiating Schemes

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Acta Mechanica Solida Sinica 2016年第3期29卷 328-336页

作者： Mehdi safari Department of Mechanical Engineering Arak University of Technology

In this paper, various strategies of spiral irradiating scheme for the flame forming of a bowl shaped surface are investigated experimentally and numerically. Experimental work is performed using a flame torch integrated with a 2-axis CNC workstation. The ABAQUS implicit solver is used in the numerical simulation. Three different strategies of the spiral irradiating scheme are investigated for the flame forming of a bowl shaped surface. The first strategy is the Simple spi- ral irradiating scheme, the second is the Rotational spiral irradiating scheme, and the third is the Symmetrical-Rotational spiral irradiating scheme. The results show that using the Symmetrical- Rotational spiral irradiating scheme, a bowl shaped surface with the maximum deformation can be produced, followed by using the Rotational scheme, and the Simple spiral scheme. It is also concluded from the results that the spiral irradiating scheme with Symmetrical-Rotational, Rota- tional and Simple spiral schemes lead to the maximum symmetries in the produced bowl shaped surface, respectively. All the numerical results are in good agreement with the experimental ob- servations.

关键词： flame forming bowl shaped surface spiral irradiating strategy

The Acoustic Performance of 3D Printed Multiple Jet Nozzles with DifferentConfigurations

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Sound & Vibration 2020年第1期54卷 43-55页

作者： Ali safari Variani Ali Dastamoz Sajad Zare ahmad Nikpey Saeid ahmadi Department of Occupational Health and Safety School of Public HealthQazvin University of Medical SciencesQazvinIran Department of Occupational Health and Safety School of Public HealthKerman University of Medical SciencesKermanIran

This work investigated multiple jet nozzles with various geometrical shape,number of exits,and material on reducing noise radiated from jet *** are categorized in two groups with few and many exit numbers,each with various exit shapes,slot and circular,and ***,nozzles are designed and then fabricated by a 3D printer,Form Labs,Form2USA,with polymeric ***,the nozzle with the most noise reduction made of stainless *** and air thrust were measured at three air pressure gauges,3,5,7 BAR and directions from nozzle apex,30°,90°,135°.Nozzles with slot exit shape made of both plastic and stainless steel revealed the most noise reduction among all nozzles with few exit numbers,nearly 11–14 dB(A)and 11.5–15 dB(A),*** average,slotted nozzle noise reduction was nearly 5–6 dB(A)more than finned ***,nozzles with more exit numbers,finned and finned-central exit,illustrated much more noise reduction than nozzles with few exit numbers,by almost 16–18 dB(A),they represented similar *** tested nozzles and open pipe demonstrated equal air thrust at each pressure *** nozzles with slotted exit shape,either plastic or stainless steel,can provide reasonable noise reduction in comparison to other configuration with few exit *** contrast,nozzles with more exit numbers demonstrated the most noise reduction.

关键词： Jet noise multiple jet nozzle noise reduction 3D design exit shape nozzle geometry

Effect of methane content and the oscillating electric field between electrodes on atmospheric Ar/methane plasma jet and DLC coating deposition

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Plasma Science and Technology 2020年第8期22卷 76-89页

作者： Reza safari Farshad SOHBATZADEH Department of Atomic and Molecular Physics Faculty of Basic SciencesUniversity of MazandaranBabolsar 47416Iran

In this work,the effects of the methane gas flow and the internal oscillating electric field between electrodes on radio-frequency(RF)atmospheric pressure argon/methane plasma jet and process of diamond-like carbon(DLC)film deposition have been *** of RF atmospheric Ar/methane plasma jet such as active species density,length,electron temperature,appearance and ionization process of argon/methane plasma jet are changed due to the changing of methane flow content and electric field vector and its *** increasing methane flow,the formation of C2 hydrocarbon and CH band content is decreased because injected electrical energy to a mixture of Ar/methane gases is insufficient to stabilize the ionization process of methane gas and the electrical-chemical reaction rate is *** shortening the gas gap between two electrodes,electric field strength and its gradient are increased leading to more energy injection to the ***-chemical reactions are strengthened leading to increasing the CH band *** phenomena introduce the Ar/methane plasma jet in different modes causing to deposit the DLC film with different structures and *** using quartz glass and alumina ceramic as dielectric barriers tubes,RF atmospheric pressure Ar/methane plasma jet has been used to deposit DLC coating in different *** methane content and shortening the gas gap leads to decreasing sp3 bonded content and the quality of the deposited film.

关键词： RF atmospheric plasma methane flow electric field

Basin Analysis and Paleogeography of the Zagros Foreland Basin during the Maastrichtian,High Zagros Basin,Iran

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Journal of Earth Science 2024年第5期35卷 1527-1545页

作者： Hossein Ghanbarloo Amrollah safari Department of Geology University of IsfahanIsfahan 81746-73441Iran

A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland *** on the study of more than 1000 rock samples,nine carbonate microfacies and three terrigenous facies were *** study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros ***(Gandom Kar area),two(Ardal area),seven(Gardbishe area),five(Shirmard area),two(Kuh-e-Kamaneh area),three(Kuh-e-Balghar area),and six(Murak area)of depositional sequences(3rd order)were *** thickness of the lowstand systems tract(LST)due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle *** the Middle Maastrichtian,the shallow and deep marine deposits were formed during the transgressive systems tract(TST)and highstand systems tract(HST)in this basin and the rate of subsidence in the center of this basin(Gardbishe area)is higher than in other areas and the platform was drowned in this *** falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin(except the south part)during the Late *** studies on the Zagros Basin during the Late Campanian-Maastrichtian showed the following results:shallow marine environments were developed in the southeast of this basin,and the turbidite,delta,and fluvial environments in the northwest were developed more than in other areas.

关键词： Maastrichtian deposits local fault depositional sequences Neotethys Basin Inception Foreland Basin Late Cretaceous basin analysis paleogeography

Effect of electrical discharge in water on concentration of nitrate solution

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Chinese Physics B 2017年第2期26卷 305-312页

作者： F Sohbatzadeh H Bagheri R safari Department of Atomic and Molecular Physics Faculty of Basic Sciences University of Mazandaran Babolsar lra

In this work, the effect of electrical discharge on nitrate concentration is considered in aqueous solution. The atmospheric pressure plasma was produced by a high-voltage power supply at 27 k Hz using pin-to-pin configuration. Air, argon,and argon/methane mixture were used to study the working gas effect. UV-VIS spectroscopy and ion chromatography were used to analyze the effect of the electrical discharge on nitrate concentration in deionized water. Optical emission spectroscopy（OES） was applied to diagnose active species inside and on the surface of the deionized water solution. The results of the present work showed that the atmospheric pressure electric discharge with air increases nitrate concentration while it remains constant using argon and argon/methane electrical discharges. It was also revealed that in the presence of air, the electrical discharge reduces p H, acidifying the solution and increasing solution conductivity due to production of extra nitrate ions. On the other hand, argon electrical discharge increases p H and conductivity due to production of OHion in water.

关键词： electric discharge nitrate solution optical spectroscopy

Local Energy Dissipation/Transition in Field Effect Molecular Nanoelectronic Systems:a Quantum Mechanical Methodology

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Communications in Theoretical Physics 2019年第4期71卷 441-454页

作者： Reza safari Hassan Sabzyan Department of Chemistry Faculty of Science University of Qom Department of Chemistry University of Isfahan

Electronic and vibrational intra-molecular thermoelectric-like ?gures of merit(ZT_γ~M) are introduced for single molecule nanoelectronic system, using quantum theory of atoms in molecule. These ?gures of merit are used to describe intra-molecular or local energy dissipation/transition(as in Joule-like, Peltier-like, and Thomson-like effects) in?eld effect molecular devices. The ZT_γ~M?gures of merit are computed for two proposed molecular devices. Analysis of the results shows that ZT_γ~Mdepends almost non-linearly on the electric ?eld(EF) strength. Also, the intra-molecular Joule-like heating plays a dominant role in the local energy dissipation, and intra-molecular Thomson-like heating is generally larger than the intra-molecular Peltier-like heating. Introduction of ZT_γ~Mcan be applied to extend the analysis of thermoelectric heating down to molecular and intra-molecular levels, and thus can be used to predict characteristics and performance of any candidate multi-terminal or multi-pole molecular systems prior to their application in real nanoelectronic circuits.

关键词： intra-molecularheattransfer local energy dissipation fieldeffect molecular device nanoelectronic devices QTAIM

Description of the biology of Caspian vimba,Vimba vimba(Linnaeus,1758),in Gorgan Bay-Miankaleh Wildlife Refuge(southeast Caspian Sea)

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Chinese Journal of Oceanology and Limnology 2010年第6期28卷 1173-1179页

作者： PATIMAR Rahman safari Sajjad Gonbad Institutes of Higher Education

We collected Vimba vimba throughout the spawning season （mid April to mid June, 2007） in Gorgan Bay （south-western Iran） and investigated its age, growth, and reproductive traits. The maximum age was 5＋ years. Both sexes grew allometrically （positive for males： b=3.140 9 and negative for females： b=2.791 4）. The von Bertalanffy growth functions were described by the formulae Lf=32.565（1-e-0.184（t＋0.530）） for males and Lt=35.950（1-e-0.179（t＋0.529）） for females. The overall sex ratio was balanced, but males were predominant in the smaller size classes and females in the larger size classes. Based on the gonadosomatic index （GSI） values, spawning appears to occur between late April and late May in the bay. The highest mean GSI was 6.44 for males in early May and 20.36 for females in late April Absolute fecundity varies from the minimum of 5 436 eggs for age 3＋ fish to the maximum of 36 141 eggs for age 5＋ fish. Fecundity was also positively correlated with fish size （length and weight）. Egg diameter ranged from 1.05 to 1.70 nun in the mean of 1.42 mm. There was no correlation between female size and ova diameter.

关键词： ~mba vimba age growth reproduction Gorgan Bay Iran