检索结果-南通市图书馆

维普期刊数据库

Strain-Rate Dependency of a Unidirectional Filament Wound Composite under Compression

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2023年第12期137卷 2149-2161页

作者： Stepan Konev Victor A.Eremeyev Hamid M.Sedighi leonid Igumnov Anatoly Bragov Aleksandr Konstantinov Ayaulym Kuanyshova Ivan Sergeichev Skolkovo Institute of Science and Technologies Center for Materials TechnologiesMoscowRussia National Research Lobachevsky State University of Nizhny Novgorod Nizhny NovgorodRussia Dipartimento di Ingegneria Civile Ambientale e Architettura(DICAAR)Universitàdegli Studi di CagliariCagliari(CA)Italy Mechanical Engineering Department Faculty of EngineeringShahid Chamran University of AhvazAhvazIran Drilling Center of Excellence and Research Center Shahid Chamran University of AhvazAhvazIran

This article presents the results of experimental studies concerning the dynamic deformation and failure of a unidirectional carbon fiber reinforced plastic(T700/LY113)under *** test samples were manufactured through the filament winding of flat *** establish the strain rate dependencies of the strength and elastic modulus of the material,dynamic tests were carried out using a drop tower,the Split Hopkinson Pressure Bar method,and standard static *** samples were loaded both along and perpendicular to the direction of the reinforcing *** applicability of the obtained samples for static and dynamic tests was confirmed through finite elementmodeling and the high-speed imaging of the deformation and failure of samples during *** a result of the conducted experimental studies,static and dynamic stress-strain curves,time dependencies of deformation and the stress and strain rates of the samples during compression were *** on these results,the strain rate dependencies of the strength and elasticity modulus in the strain rate range of 0.001-6001/s are *** is shown that the strain rate significantly affects the strength and deformation characteristics of the unidirectional carbon fiber composites under *** increase in the strain rate by 5 orders of magnitude increased the strength and elastic modulus along the fiber direction by 42%and 50%,*** loading resulted in a strength and elastic modulus increase by 58%and 50%,*** average strength along the fibers at the largest studied strain rate was about *** obtained results can be used to design structural elements made of polymer composite materials operating under dynamic shock loads,as well as to build models of mechanical behavior and failure criteria of such materials,taking into account the strain rate effects.

关键词： High strain rate composites filament winding dynamic strength Split Hopkinson Pressure Bar compression

High-pressure, High-temperature Synthesis and Properties of the Monoclinic Phase of Y2O3

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2016年第4期32卷 545-548页

作者： ZHANG Qian WU Xiang OVSYANNIKOV V. Sergey DONG Juncai QIN Shan DUBROVINSKY S. leonid CHEN Dongliang Gemological Institute China University of Geosciences Wuhan 430074 P. R. China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 P R. China Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education & School of Earth and Space Sciences Peking University Beo'ing 100871 P. R. China Bayerisches Geoinstitut Universitat Bayreuth Bayreuth D-95447 Germany Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 P. R. China

The monoclinic phase of Y2O3（B-RES） has been synthesized using a Kawai-type multi-anvil apparatus under 20 GPa at 1800℃. Samples of the cubic Y2O3（C-RES） and monoclinic Y2O3 phases were characterized by synchrotron radiation X-ray diffraction, X-ray absorption near edge structure and Raman spectroscopy. Crystal structures of the cubic and monoclinic phases have been examined using Rietveld refinement of the X-ray diffraction data. The cubic-to-monoclinic transition of Y2O3 was reconstructive and irreversible. The X-ray diffraction results were further confirmed by simulation of the X-ray absorption spectra.

关键词： Y2O3 High pressure Multi-anvil synthesis

Ignition of nanothermites by a laser diode pulse

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2022年第2期18卷 194-204页

作者： Alexander Yu.Dolgoborodov Vladimir G.Kirilenko Michael A.Brazhnikov leonid I.Grishin Michael L.Kuskov Georgii E.Valyano Joint Institute for High Temperatures Russian Academy of SciencesRussia N.Semenov Federal Research Center for Chemical Physics Russian Academy of SciencesRussia National Research Nuclear University MEPhI Moscow Russia

Experimental investigation has been carried out for laser ignition and combustion of nanothermites based on aluminum and oxides of copper,bismuth and *** mixing of nanosized powders was used to produce *** thermite ignition,initiating laser pulse with a maximum intensity of 770 W/cm2 was generated by a laser diode with a wavelength of 808 *** ignition delay times,the minimum initiation energy density,and the average burning rate at various thermite densities and mass fractions of components were determined by recording the emission of radiation of the reaction products using a multichannel pyrometer jointly with a high-speed video *** effect of adding carbon black on the threshold parameters of a laser pulse was also *** on the obtained results,certain assumptions were put forward with regard to the mechanism of nanothermites’ignition by laser radiation and their *** particular,the assumptions were made on the two-stage process of the reaction initiation and jet burning mechanism of porous nanothermites.

关键词： Nanothermites Laser ignition Burning rate Ignition delay

维普期刊数据库

Impact of Climate and Grazing on Biomass Components of Eastern Russia Typical Steppe

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2014年第6期13卷 1183-1192页

作者： Ubugunov leonid Rupyshev Yuriy Ubugunov Vasiliy HOU Xiang-yang Vishnyakova Oxana Lavrentieva Irina Ubugunova Vera REN Wei-bo DING Yong Institute of General and Experimental Biology Siberian Branch of Russian Academy of Sciences Grassland Research Institute Chinese Academy of Agricultural Sciences

Spatial and structural characteristics of plant communities in the steppe ecosystems of the Baikal region, Russian Federation have been researched in connection with climate change and grazing. The present study, based on a total of 15 typical steppe sampling plots, investigated above-ground biomass （AGB）, below-ground biomass （BGB）, total biomass （TB） and root：shoot ratios （R：S） and their relationships with climatic factors and grazing. All biomass components varied widely depending on the climatic parameters and the degree of grazing affected transformation. A strong negative correlation between mean annual temperature （MAT） and total plant biomass was revealed for all study area. Mean annual precipitation （MAP） signiifcantly affected communities productivity increasing only in the south of the region. Due to the large and mountainous territory, the inlfuence of latitude and elevation （mountain） factors on the components of the biomass were studied. Although all studied plant steppe communities were transformed by uncontrolled grazing, their productivity is signiifcantly reduced only at plots with maximum digression. Vegetation shift is an indicator of climate change, as well as providing a diagnostic tool to build predictive models. Based on the complex index of effective precipitation, it was revealed that at the end of last century in the steppes of the Baikal region the structural and production processes will be affected by an arid climate trend.

关键词： steppe productivity climate grazing transformation Baikal region

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

不可逆转的全球老龄化:趋势与应对

延边大学学报(社会科学版) 2024年第5期57卷 129-138+144页

作者： Л.Е.格里宁 А.Л.格里宁 А.В.科罗塔耶夫张广翔师成俄罗斯国立高等经济大学社会政治动荡风险监测实验室莫斯科国立大学全球化进程系吉林大学东北亚研究中心

文章分析了对21世纪社会生活各领域产生重大影响的全球人口老龄化进程。这一进程的影响将取决于其规模和深度，也可以说取决于未来社会的人口结构。同时，现代社会是否能够应对全球人口老龄化所带来日益严峻的挑战也是一大问题。鉴于到2... 详细信息

文章分析了对21世纪社会生活各领域产生重大影响的全球人口老龄化进程。这一进程的影响将取决于其规模和深度，也可以说取决于未来社会的人口结构。同时，现代社会是否能够应对全球人口老龄化所带来日益严峻的挑战也是一大问题。鉴于到21世纪中叶，全球65岁以上人口将有2/3生活在中低收入国家，所以这一挑战尤其令人担忧。全球老龄化已经是不容忽视的时代主题，为老年人提供社会保障和医疗保健服务也将是艰巨的任务。时至今日，不应再将老龄化视作负面现象，而应将老一代人的智慧和经验视为未来社会发展的新机遇。因此，有必要在各领域采取具体措施并实施专门的长期政策，改善老年人的健康水平，提高其生活质量与预期寿命，消除对死亡的偏见。实现这些目标是高度依赖技术进步的，同时全球老龄化进程所催生的新需求也会倒逼技术发展，尤其是在技术爆炸即将到来的背景下，可能会对节省劳动力的技术、延长寿命的技术产生巨大需求，这也将有力地推动医学进步，有助于延长工作年限和提高人类生活质量。

关键词：全球老龄化社会人口结构控制论革命养老金危机老龄歧视

Mathematical Model of Embodied Symbols: Cognition and Perceptual Symbol System

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Behavioral and Brain Science 2012年第2期2卷 195-220页

作者： leonid Perlovsky Roman Ilin Air Force Research Laboratory Wright-Patterson Air Force Base Greene & Montgomery Ohio USA Harvard University Cambridge USA

A mathematical model of perceptual symbol system is developed. This development requires new mathematical methods of dynamic logic (DL), which have overcome limitations of classical artificial intelligence and connectionist approaches. The paper discusses these past limitations, relates them to combinatorial complexity (exponential explosion) of algorithms in the past, and relates it further to the static nature of classical logic. DL is a process-logic;its salient property is evolution of vague representations into crisp. We first consider one aspect of PSS: situation learning from object perceptions. Next DL is related to PSS mechanisms of concepts, simulators, grounding, embodiment, productiveity, binding, recursion, and to the mechanisms relating embodied-grounded and amodal symbols. We discuss DL capability for modeling cognition on multiple levels of abstraction. PSS is extended toward interaction between cognition and language. Experimental predictions of the theory are discussed. They might influence experimental psychology and impact future theoretical developments in cognitive science, including knowledge representation, and mechanisms of interaction between perception, cognition, and language. All mathematical equations are also discussed conceptually, so mathematical understanding is not required. Experimental evidence for DL and PSS in brain imaging is discussed as well as future research directions.

关键词： Perceptual Symbol System Embodied Cognition Perception Knowledge Representation Grounded Symbols Dynamic Logic

Turbulence Modeling Applied to Flow over a Hydraulic Ball Check Valve

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering（科研） 2013年第8期5卷 685-691页

作者： leonid Grinis Vitaly Haslavsky Mechanical Engineering Sami Shamoon College of Engineering Beer-Sheva Israel

This paper describes an experimental, theoretical model, and a numerical study of concentrated vortex flow past a ball in a hydraulic check valve. The phenomenon of the rotation of the ball around the axis of the device, through which liquid flows, has been found. That is, vibration is caused by the rotation of the ball in the check valve. We observe the rotation of the ball around the longitudinal axis of the check valve. This rotation is induced by vortex shedding from the ball. We will discuss computational simulation and experimental investigations of this strong ball rotation. The frequency of the ball vibration and interaction with the check valve wall has been measured as a function of a wide range of Reynolds numbers. The validity of the computational simulation and of the assumptions on which it is based has been proved experimentally. This study demonstrates the possibility of controlling the vibrations in a hydraulic system and proves to be a very effective suppression of the self-excited vibration.

关键词： Check-Valve Vibration Vortex Shedding

A Variation Account of Divergent Thinking

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Literature and Art Studies 2017年第8期7卷 1039-1053页

作者： leonid Dorfman Vera Gassimova Perm State Institute of Culture Perm Russia

A variation account was applied to divergent thinking accommodated as a kind of creative thinking. To provide control （contrast） condition the variation account was applied to psychometric intelligence. Guilford＇s （1956, 1967, 1988） theory of divergent-----convergent thinking served the background of our study. The main premise was that creative variation represents ＂thought trials＂ with diverse ways to find a solution to the problem. Task demands and the respective creative problem solving reveal advantageous sources that suggest the variation. Probably, uncertainty, information search, and finding alternatives extracted from memory precede, entail and provide variety of seeking, as well. A principal hypothesis to be tested was that divergent thinking enables its variation rather than intelligence does that to its variation. As predicted, the divergent thinking and its variation were related. Compared to uncreative, creative persons were characterized by larger variation. Apart from the mathematical intelligence, other kinds of intelligence and their variation did not correlate. Mainly, the data obtained, thus, lend support to the claimed hypothesis.

关键词： variation creativity divergent thinking intelligence scattering

Possible Signs of Life on the Planet Venus

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Astronomy and Astrophysics 2013年第1期3卷 57-79页

作者： leonid V. Ksanfomality Space Research Institute of the RAS Moscow Russia

It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of the nearest planet of the Solar system. The search for “habitable zones” in extrasolar planetary systems is based on the postulate on “normal” physical conditions, i.e., the pressure, temperature, and maybe atmospheric composition similar to those on Earth. But could not such an approach be a kind of “terrestrial chauvinism”? Considering the conditions on Venus as a possible analogue of physical conditions on low-orbiting exoplanets of the “super-Earths” type, a new analysis of Venusian surface panoramas’ details has been made. These images were produced by the VENERA landers in 1975 and 1982. A few relatively large objects were found with size ranging from a decimeter to half meter and with unusual morphology. The objects were observed in some images, but were absent in the other or altered their shape. The article presents the obtained results and analyzes the evidence of reality of these objects.

关键词： Extraterrestrial Life Venus Physical Conditions