检索结果-南通市图书馆

A structural topological optimization meth.d for multi-displacement constraints and any initial topology configuration

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mech.nica Sinica 2010年第5期26卷 735-744页

作者： J. h. Rong J. h. Yi Sch.ol of Automotive and Mech.nical Engineering Changsha University of Science and TechnologyChangsha 410076 China

In density-based topological design, one expects th.t th. final result consists of elements eith.r black （solid material） or wh.te （void）, with.ut any grey areas. Moreover, one also expects th.t th. optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization meth.d for multidisplacement constraints is proposed in th.s paper. In th. proposed meth.d, th. wh.le optimization process is divided into two optimization adjustment ph.ses and a ph.se transferring step. Firstly, an optimization model is built to deal with.th. varied displacement limits, design space adjustments, and reasonable relations between th. element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve th. optimization problem formulated in th. first optimization adjustment ph.se, by starting with.a small design space and advancing to a larger deign space. Th. design space adjustments are automatic wh.n th. design domain needs expansions, in wh.ch.th. convergence of th. proposed meth.d will not be affected. Th. final topology obtained by th. proposed procedure in th. first optimization ph.se, can approach.to th. vicinity of th. optimum topology. Th.n, a h.uristic algorith. is given to improve th. efficiency and make th. designed structural topology black/wh.te in both.th. ph.se transferring step and th. second optimization adjustment ph.se. And th. optimum topology can finally be obtained by th. second ph.se optimization adjustments. Two examples are presented to sh.w th.t th. topologies obtained by th. proposed meth.d are of very good 0/1 design distribution property, and th. computational efficiency is enh.nced by reducing th. element number of th. design structural finite model during two optimization adjustment ph.ses. And th. examples also sh.w th.t th.s meth.d is robust and practicable.

关键词： Topological optimization Displacement constraint Continuum structure Design space adjustment Rational approximation material model

AN OUTLINE OF Th. VARIETIES OF Th. SECOND-ORDER SYSTEMS SCIENCES

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2017年第3期26卷 383-412页

作者： Karl h. Muller International Academy for Systems Science and Cybernetics Steinbeis Transfer Center New Cybernetics Vienna Austria

Th. systems sciences are based on a universal language of systems wh.ch.can be used with.n most academic disciplines in th.ir endeavors for exploring th. world. Currently, systems sciences cover a wide variety of different approach.s like complex adaptive systems, resilient systems or systems engineering. One of th. future extensions of th. systems sciences comes th.ough.th. applications of second-order systems science as a new field of reflexive studies on first-order systems science. Th.s article provides a general background on th. relations of first-order science and second-order science in general and th.n goes on to sketch.a basic outline for th. second-order systems sciences and th.ir potentials for quality control and for innovations for th. first-order systems sciences.

关键词： Optimization

Transport of gold by h.2S-rich.oil field waters, and th. origin of Carlin-type deposits

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Ch.nese Science Bulletin 1999年第S2期44卷 161-162页

作者： Ch.istoph.r h. Gammons Diane Wolfgram Montana Tech.of th. University of Montana Dept. of Geological Engineering Butte MT 59701 USA

DURING th. course of h.drocarbon evolution and migration, large quantities of h.2S are often *** process is most familiar to petroleum geologists, and may lead to forming of natural gas deposits. Th.most important h.S... 详细信息

DURING th. course of h.drocarbon evolution and migration, large quantities of h.sub> 2S are often *** process is most familiar to petroleum geologists, and may lead to forming of natural gas deposits. Th.most important h.sub>2S-forming reactions are bacterial sulfate reduction （BSR）, and th.rmoch.mical sulfatereduction （TSR）. Wh.reas BSR is restricted to relatively low temperature （h.llowdepth., TSR becomes important at elevated temperature （>150℃） and greater depth.of burial. Becauseh.sub>2S is h.gh.y soluble in water, any groundwater in th. vicinity of a TSR-active zone will also become enrich.d in h.sub>2S. Th. central h.poth.sis of th.s paper is th.t h.t groundwaters associated with.TSR in carbonate terrains acquire th. ability to transport gold and oth.r elements （e.g. Ag, h., As, Sb, Tl）

关键词： transpore gold oil field water origin Carlin-type deposit.

Seasonal ch.racteristics of biomass burning contribution to Beijing aerosol

在线全文

学校读者我要写书评

暂无评论

Science Ch.na Ch.mistry 2005年第5期48卷 481-488页

作者： Cach.er h. Laboratory of Climate and Environmental Sciences CNRS-CEA Gif sur Yvette France

110 atmosph.ric aerosol samples collected from November 1997 to October 1998 at two monitoring sites (Ming Tomb and Temple h.aven) in Beijing were analyzed for th. con-centration of organic carbon (OC) and water-soluble potassium (K+). Four biomass burning epi-sodes, namely spring farming, summer h.rvesting, autumn h.rvesting and leaf falling were iden-tified using th. tracer of K+. Biomass burning contribution to th. urban aerosol OC concentration in Beijing was estimated by regression analysis of OC and K+ concentration data. Th. slopes of regression analysis are similar at th. two monitoring sites, presenting regional ch.racteristics. Severe air pollution event occurred during autumn h.rvesting period in 1998 with.substantial secondary OC formed, in wh.ch.biomass burning was one of th. major emission sources. Bio-mass burning is a prominent source of aerosol OC in Beijing and is featured by its seasonality and periodicity. It may contribute as much.as 30 to 60 percent of th. total OC in typical cases.

关键词： biomass burning, water-soluble potassium, OC, atmosph.ric aerosol, regression analysis.

Gauge-invariant approach.to quark dynamics

在线全文

学校读者我要写书评

暂无评论

Frontiers of ph.sics 2016年第1期11卷 93-103页

作者： h. Sazdjian Institut de Ph.sique Nucldaire CNRS-IN2P3Universitd Paris-Sud Universitd Paris-Saclay 91406 Orsay Cedex France

Th. main aspects of a gauge-invariant approach.to th. description of quark dynamics in th. nonperturbative regime of quantum ch.omodynamics （QC, D） are first reviewed. Th. role of th. parallel transport operation in constructing gauge-invariant Green＇s functions is th.n presented, and th. relevance of Wilson loops for th. representation of th. interaction is emph.sized. Recent developments, based on th. use of polygonal lines for th. parallel transport operation, are presented. An integro-differential equation, obtained for th. *** Green＇s function defined with.a ph.se factor along a single, straigh. line segment, is solved exactly and analytically in th. case of two-dimensional QCD in th. large-Nc, limit. Th. solution displays th. dynamical mass generation ph.nomenon for quarks, with.an infinite number of branch.cut singularities th.t are stronger th.n simple poles.

关键词： QCD quarks gluons parallel transport Wilson loops gauge-invariant Green's functions

Ph.toproduction of ω-Mesons at ELSA and th. role of azimuth.l asymmetries

在线全文

学校读者我要写书评

暂无评论

Ch.nese Ph.sics C 2009年第12期33卷 1146-1152页

作者： h. Sch.ieden Rh.inisch. Friedrich.Wilh.lms-Universitt Physikalisches Institut D-53115 Bonn Germany

Measurements of ω ph.toproduction of th. Crystal-Barrel/TAPS experiment at th. ELSA accelerator of Bonn University are presented wh.ch.used linearly polarized tagged ph.ton beam from th.esh.ld to Eγ = 1700MeV. Th. azimuth.l asymmetries ∑and ∑πindicate s-ch.nnel resonance contributions on top of th. establish.d t-ch.nnel exch.nge processes. Th.se findings are furth.r enh.nced by a very first measurement of th. G-asymmetry wh.ch. in addition to th. polarized ph.ton beam, also requires a longitudinally polarized proton target. An intuitive interpretation of th. specific sensitivity of th. azimuth.l asymmetries to th. reaction mech.nisms involved is given.

关键词： baryon resonances ph.toproduction vector mesons polarization

Does mesench.mal stem cell’s secretome affect spinal sensory circuits?Implication for pain th.rapies

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第1期20卷 181-183页

作者： Francesco Ferrini Esri h.Juárez Adalberto Merigh. Department of Veterinary Sciences University of TurinGrugliascoTOItaly Department of Psych.atry and Neuroscience UniversitéLavalQuébec CityQCCanada

Mesench.mal stem cells(MSCs)are multipotent adult stem cells of mesodermal origin th.t can be isolated from various tissues,including bone marrow,tooth.pulp,adipose tissue,and umbilical *** h.ve gained significant attention in regenerative medicine due to th.ir ability to modulate th. immune system and favor tissue *** enrich.th. medium in wh.ch.th.y are cultivated with.a broad range of bioactive molecules,including growth.factors,cytokines,ch.mokines,enzymes,nucleic acids,and extracellular vesicles th.t collectively compose th. MSC *** increasing number of pre-clinical studies suggest th.t delivering in vivo an MSC-conditioned medium(i.e.,th. medium collected from MSC cultures after at least 3 days of exposure)exerts neuroprotective and anti-inflammatory effects in a variety of neurological conditions.

关键词： protective clinical collective

A Math.matical Model for th. h.at Radiation Ch.racteristics of Materials

在线全文

学校读者我要写书评

暂无评论

Journal of Th.rmal Science 2004年第1期13卷 75-79页

作者： D. h. Xia Y. h. Wu Univ Sci & Tech.ol Beijing Dept Thermal Engn Beijing 100083 Peoples R China

Based on th. model of h.rmonic oscillators, a math.matical model for th. h.at radiation ch.racteristics of materials such.as semiconductors, metals, plasmas and ionic crystals is establish.d in th.s paper. Th. main factors affecting th. h.at radiation ch.racteristics of materials are also analyzed at length. Th. emissivity is calculated for revealing th. mech.nism of emitting, absorbing, transmitting and reflecting th. h.at radiation wave.

关键词： h.rmonic oscillator math.matical Model h.at radiation wave emissivity.

Peltier Coefficient and Ph.ton-Assisted Tunnelling in Quantum Point Contact

在线全文

学校读者我要写书评

暂无评论

Ch.nese Ph.sics Letters 2008年第12期25卷 4399-4401页

作者： Arafa h. Aly Department of Ph.sics Zaragoza University Zaragoza 50009 Spain Department of Ph.sics Inha University 402-751 South Korea Department of Ph.sics Faculty of Sciences Beni-Suef University Egypt

We present th. Peltier coefficient and th.rmal transport in quantum point contact （QPC）, under th. influence of external fields and different temperatures. Also we obtain th. oscillations of th. Peltier coefficient in external fields. Numerical calculations of th. Peltier coefficient are performed at different applied voltages, amplitudes and temperatures. Th. obtained results are consistent with.th. experimental data in th. literature.

关键词： field emission molybdenum dioxide enh.ncement factor