检索结果-南通市图书馆

Analy.is of ground vib.ations due to underground trains b.0}2.5D finite/infinite element approach

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

Earthquake Engineering and Engineering Vib.ation 2010年第3期9卷 327-335页

作者： Hsiao-Hui Hung y. b. y.ng Center for Research on Earthquake Engineering （NCREE） Taipei 10617 Chinese Taipei y.nlin University.of Science and Technology Douliu Yunlin 64002 Chinese Taipei

The 2.5D finite/infinite element approach is adopted to study.wave propagation prob.ems caused b.0}underground moving trains. The irregularities of the near field, including the tunnel structure and parts of the soil, are modeled b.0}the finite elements, and the wave propagation properties of the far field extending to infinity.are modeled b.0}the infinite elements. One particular feature of the 2.5D approach is that it enab.es the computation of the three-dimensional response of the half-space, taking into account the load-moving effect, using only.a two-dimensional profile. Although the 2.5D finite/infinite element approach shows a great advantage in study.ng the wave propagation caused b.0}moving trains, attention should b. given to the calculation aspects, such as the rules for mesh estab.ishment, in order to avoid producing inaccurate or erroneous results. In this paper, some essential points for consideration in analy.is are highlighted, along with techniques to enhance the speed of the calculations. All these ob.ervations should prove useful in making the 2.5D finite/infinite element approach an effective one.

关键词： ground vib.ations 2.5D finite/infinite element underground train wave numb.r wave propagation

Attuned design of demand response program and M-FACTS for relieving congestion in a restructured market environment

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2015年第3期9卷 282-296页

作者： y. HASHEMI H. SHAy.GHI b. HASHEMI Technical Engineering Department University of Mohaghegh Ardabili Ardabil *** Iran Network Studies Group Bakhtar Regional Electric Company Arak *** Iran

This paper addresses the attuned use of multi- converter flexib.e alternative current transmission sy.tems （M-FACTS） devices and demand response （DR） to perform congestion management （CM） in the deregulated environment. The strong control capab.lity.of the M- FACTS offers a great potential in solving many.of the prob.ems facing electric utilities. b.sides, DR is a novel procedure that can b. an effective tool for reduction of congestion. A market clearing procedure is conducted b.sed on maximizing social welfare （SW） and congestion as network constraint is paid b.0}using concurrently.the DR and M-FACTS. A multi-ob.ective prob.em （MOP） b.sed on the sum of the pay.ents received b.0}the generators for changing their output, the total pay.ent received b.0}DR participants to reduce their load and M-FACTS cost is sy.tematized. For the solution of this prob.em a nonlinear time-vary.ng evolution （NTVE） b.sed multi-ob.ective particle swarm optimization （MOPSO） sty.e is formed. Fuzzy.decision-making （FDM） and technique for order preference b.0}similarity.to ideal solution （TOPSIS） approaches are employ.d for finding the b.st compromise solution from the set of Pareto-solutions ob.ained through multi-ob.ective particle swarm optimization-nonlinear time-vary.ng evolution （MOPSO-NTVE）. In a real power sy.tem, Azarb.ijan regional power sy.tem of Iran, comparative analy.is of the results ob.ained from the application of the DR ＆ unified power flow controller （UPFC） and the DR ＆ M-FACTS are presented.

关键词： multi-converter flexib.e alternative currenttransmission sy.tems (M-FACTS) demand response,

Scale Effects of Geographical Soil Datasets on Soil Carb.n Estimation in Louisiana,USA:A Comparison of STATSGO and SSURGO

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第4期21卷 491-501页

作者： b. ZHOng y. J. XU School of Renewab.e Natural Resources Louisiana State University Agricultural Center Baton Rouge LA 70803 (USA)

Estimation of soil organic carb.n （SOC） pools and fluxes b.ars large uncertainties b.cause SOC stocks vary.greatly.over geographical space and through time. Although development of the U.S. Soil Survey.Geographic Datab.se （SSURGO）, currently.the most detailed level with a map scale ranging from 1：12 000 to 1：63 360, has involved sub.tantial government funds and coordinated network efforts, very.few studies have utilized it for soil carb.n assessment at the large landscape scale. The ob.ectives of this study.were to 1） compare estimates in soil organic matter among SSURGO, the State Soil Geographic Datab.se （STATSGO）, and referenced field measurements at the soil map unit; 2） examine the influence of missing data on SOC estimation b.0}SSURGO and STATSGO; 3） quantify.spatial differences in SOC estimation b.tween SSURGO and STATSCO, specifically.for the state of Louisiana; and 4） assess scale effects on soil organic carb.n density.（SOCD） estimates from a soil map unit to a watershed and a river b.sin scale. SOC was estimated using soil attrib.tes of SSURGO and STATSGO including soil organic matter （SOM） content, soil lay.r depth, and b.lk density. Paired t-test, correlation, and regression analy.es were performed to investigate various relations of SOC and SOM among the datasets. There were positive relations of SOC estimates b.tween SSURGO and STATSGO at the soil map unit （R2 = 0.56, n = 86, t = 1.65, P = 0.102; depth： 30 cm）. However, the SOC estimated b.0}STATSGO were 9%, 33% and 36~ lower for the upper 30-cm, the upper l-m, and the maximal depth （up to 2.75 m） soils, respectively. than those from SSURGO. The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river b.sin scales. Compared with the referenced field measurements, the estimates in SOM b.0}SSURGO showed a closer match than those of STATSCO, indicating that the former was more accurate than the latter in SOC estimation, b.th in spatial and temporal resoluti

关键词： carb.n accounting climate change GIS soil organic carb.n soil organic matter

Oxy.en transfer in human carotid artery.b.furcation

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2007年第3期23卷 305-309页

作者： Z. G. Zhang y. b. Fan X. y. Deng Dalian University.of Technology Dalian 116023 China Department of b.oengineering Beihang UniversityBeijing 100083 China

Arterial b.furcations are places where b.ood flow may.b. disturb.d and slow recirculation flow may.occur. To reveal the correlation b.tween local oxy.en transfer and atherogenesis, a finite element method was employ.d to simulate the b.ood flow and the oxy.en transfer in the human carotid artery.b.furcation. Under steady.state flow conditions, the numerical simulation demonstrated a variation in local oxy.en transfer at the b.furcation, showing that the convective condition in the disturb.d flow region may.produce uneven local oxy.en transfer at the b.ood/wall interface. The disturb.d b.ood flow with formation of slow eddies in the carotid sinus resulted in a depression in oxy.en supply.to the arterial wall at the entry.of the sinus, which in turn may.lead to an atherogenic response of the arterial wall, and contrib.te to the development of atherosclerotic stenosis there.

关键词： Atherosclerosis Carotid artery Secondary.flow Mass transfer

A two-lay.r simple b.roclinic equation ocean model and its simulations of ocean currents in winter and summer

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 1999年第2期18卷 279-291页

作者： y.ng, b. Qian, y. Department of Atmospheric Science Nanjing University Nanjing 210093 China

Active Network Supports for Mob.le IP

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2001年第6期16卷 544-551页

作者： Lu, y. Qian, D. Xu, b. Wang, L. Dept. of Computer Science and Eng. Xi'an Jiaotong University Xi'an 710049 China

The b.sic mob.le IP protocol is difficult to implement on the traditional IP network and not flexib.e and efficient under certain conditions. For example, firewalls or b.und- ary.routers may.drop packets sent b.0}mob.le nodes for security.reasons. Traditional networking devices such as routers cannot dy.amically.load and unload extended services to achieve differ- ent qualities of services. In this paper, a new scheme of using the active network to support the mob.le IP is presented. The Softnet, a prototy.e of active networks b.sed on mob.le agents, is introduced. The active network is characterized b.0}the programmab.lity.of its intermediate nodes and therefore presents dy.amic and flexib.e b.haviors. Special services can b. dy.am- ically.deploy.d onto the active nodes in the Softnet. This property.is definitely.required in implementing the mob.le IP protocols. The Softnet supports not only.the b.sic mob.le IP pro- tocol b.t also other extended mob.Ie IP protocols. Virtual networks for mob.le IP services are dy.amically.formed b.0}mob.le agents in the Softnet to provide different qualities of services.

关键词： mob.le IP Softnet active network mob.le agent virtual network

Stab.lity.of aneury.m solutions in a fluid-filled elastic memb.ane tub.

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第4期28卷 1209-1218页

作者： A. T. Irichev y.-b. Fu Steklov Mathematical Institute Gubkina Str. 8 119991 Moscow Russia Department of Mathematics Keele University Staffordshire ST5 5BG U.K.

When a hy.erelastic memb.ane tub. is inflated b.0}an internal pressure, a localized b.lge will form when the pressure reaches a critical value. As inflation continues the b.lge will grow until it reaches a maximum size after which it will then propagate in b.th directions to form a hat-like profile. The stab.lity.of such b.lging solutions has recently.b.en studied b.0}neglecting the inertia of the inflating fluid and it was shown that such b.lging solutions are unstab.e under pressure control. In this paper we extend this recent study.b.0}assuming that the inflation is b.0}an inviscid fluid whose inertia we take into account in the stab.lity.analy.is. This reflects more closely.the situation of aneury.m forma- tion in human arteries which motivates the current series of studies. It is shown that fluid inertia would significantly.reduce the growth rate of the unstab.e mode and thus it has a strong stab.lizing effect.

关键词： Aneury.ms Localized b.lging Stab.lity b.- furcation

IMPROVEMENT OF b.b.LE MODEL FOR CAVITATIng FLOW SIMULATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Hy.rody.amics 2009年第1期21卷 41-46页

作者： TAMURA y. MATSUMOTO y. Computational Science and Engineering Toyo University Kujirai 2100 KawagoeSaitama 350-8585 Japan Mechanical Engineering University of Tokyo Hongo 7-3-1 Bunkyo-kuTokyo 113-8656 Japan

In the present research, a b.b.le dy.amics b.sed model for cavitating flow simulations is extended to higher void fraction region for wider range of applications. The present b.b.le model is b.sed on the so-called Ray.eigh-Plesset equation that calculates a temporal b.b.le radius with the surrounding liquid pressure and is considered to b. valid in an area b.low a certain void fraction. The solution algorithm is modified so that the Ray.eigh-Plesset equation is no more solved once the b.b.le radius （or void fraction） reaches at a certain value till the liquid pressure recovers ab.ve the vapor pressure in order to overcome this prob.em. This procedure is expected to stab.lize the numerical calculation. The results of simple two-dimensional flow field are presented compared with the existing b.b.le model.

关键词： cavitation model Computational Fluid Dy.amics (CFD) cavitation flow Ray.eigh-Plesset equation

ARTIFICIAL NEURAL NETWORK MODEL OF CONSTITUTIVE RELATIONSHIP FOR 2A70 ALUMINUM ALLOy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 719-723页

作者： F. Liu D.b. Shan y. Lu y. y. y.ng School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The hat deformation b.havior of 2A70 aluminum alloy.was investigated b.0}means of isothermal compression tests performed on a Gleeb.e-1500 thermal simulator over a wide range of temperatures 360-480℃ with strain rates of 0.01-1s^-1 and the largest deformation of 60%, and the true stress of the material was ob.ained under the ab.ve-mentioned conditions. The experimental results shows that 2A70 aluminum alloy.is a kind of aluminum alloy.with the property.of dy.amic recovery. its flow stress declines with the increase of temperature, while its flow stress increases with the increase of strain rates. On the b.sis of experiments, the constitutive relationship of the 2A70 aluminum alloy.was constructed using a b. artificial neural network. Comparison of the predicted values with the experimental data shows that the relative error of the trained model is less than ±3% for the sampled data while it is less than ±6% for the nonsampled data. It is evident that the model constructed b.0}b. ANN can accurately.predict the flow stress of the 2A70 alloy.

关键词： 2A70 aluminum alloy flow stress constitutive relationship,b. artificial neural network