检索结果-南通市图书馆

Artificial boundary conditions for Euler–Bernoulli beam equation

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 Mechanica Sinica 2014年第5期30卷 687-692页

作者： Shao-Qiang.Tang.eduard g.karpov HEDPS CAPT and LTCS College of EngineeringPeking University Department of Civil and Materials Eng.neering University of Illinois at ChicagoChicago IL60607 USA

In a semi-discretized Euler-Bernoulli beam equa- tion, the non-nearest neig.boring.interaction and larg. span of temporal scales for wave propag.tions pose challeng.s to the effectiveness and stability for artificial boundary treat- ments. With the discrete equation reg.rded as an atomic lattice with a three-atom potential, two accurate artificial boundary conditions are first derived here. Reflection co- efficient and numerical tests illustrate the capability of the proposed methods. In particular, the time history treatment g.ves an exact boundary condition, yet with sensitivity to nu- merical implementations. The ALEX （almost EXact） bound- ary condition is numerically more effective.

关键词： Euler-Bernoulli beam. Artificial boundary con- dition - Wave propag.tion

An SPH Framework for Earthquake-Induced Liquefaction Hazard Assessment of g.otechnical Structures

在线全文

学校读者我要写书评

暂无评论

Computer Modeling.in Eng.neering.& Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.Ramana Department of Civil Eng.neering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses sig.ificant risks to the stability of g.otechnical structures *** understanding.of the liquefaction trig.ering.and the post-failure larg. deformation behaviour is essential for desig.ing.resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of g.otechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading.is described using.the PM4Sand model implemented in a three-phase,sing.e-layer SPH framework.A stag.ered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energ. modes and tensile ***,non-reflecting.boundary conditions for seismic analysis of semi-infinite soil domains using.the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level g.ound site,and liquefaction-induced failure of the Lower San Fernando *** ag.eement for liquefaction trig.ering.and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading.on field-scale g.otechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake g.otechnical eng.neering.

关键词： Earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPH)

g.ycine-nitrate combustion eng.neering.of neodymium cobaltite nanocrystals

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

Rare Metals 2021年第7期40卷 1778-1784页

作者： Ekaterina Alekseevna Tug.va Oleg.Nikolaevich karpov New Inorg.nic Materials Laboratory Ioffe InstituteSaint-Petersburg 194021.Russia Department of Physical Chemistry Saint Petersburg Electrotechnical University“LETT”Saint-Petersburg 197376Russia

NdCoO_(3)nanocrystals formed via g.ycine-nitrate combustion method followed by heat treatment has been systematically *** of NdCoO_(3)nanocrystals with minimal size of 7-10 nm from X-ray amorphous combustion products has been elucidated to be a very rapid process,occurring.at the temperature of 550-600℃for5-30 *** comparison of the minimum sizes of NdCoO_(3)crystallites obtained from the offered empirical relation dmin=lunit cell·N(where N is 7-12 and‘unit cellis elementary cell parameter)and the data determined on the basis of X-ray diffraction(XRD)and transmission electron microscopy(TEM)showed g.od *** existence of special nanoporous microstructure and spatial limitations prevent NdCoO_(3)particle *** kinetic equation based on Avrami-Erofeev nucleation model was offered to be correlated well with experimental data of fractional conversion(a)versus isothermal time(s).The apparent activation energ.(Ea=(338±32)kJ)of formation of NdCoO_(3)nanocrystals from X-ray amorphous combustion products obtained in excess of oxidant followed by heat treatment at 550-600℃was determined.

关键词： Rare earths Perovskite Kinetics Mechanism Combustion synthesis Nucleation

Stepping.up after spinal cord injury:neg.tiating.an obstacle during.walking

在线全文

学校读者我要写书评

暂无评论

Neural Reg.neration Research 2025年第7期20卷 1919-1929页

作者： Alain Frig.n Charly g.Lecomte Department of Pharmacolog.-Physiolog. Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

Every day walking.consists of frequent voluntary modifications in the g.it pattern to neg.tiate *** spinal cord injury,stepping.over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including.the parietal cortex,premotor cortex,and motor *** information and planning.are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including.humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping.over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiolog. obstacle neg.tiation spinal cord injury

Stable and accurate schemes for smoothed dissipative particle dynamics

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(Eng.ish Edition) 2018年第1期39卷 83-102页

作者： g. FAURE g. STOLTZ CEA DAM DIF Arpajon F-91297 France Universite Paris-Est CERMICS (ENPC) INRIA Marne-la-Vallee F-77455 France

Smoothed dissipative particle dynamics （SDPD） is a mesoscopic particle method that allows to select the level of resolution at which a fluid is simulated. The numerical integ.ation of its equations of motion still suffers from the lack of numerical schemes satisfying.all the desired properties such as energ. conservation and stability. Similarities between SDPD and dissipative particle dynamics with energ. （DPDE） con- servation, which is another coarse-g.ained model, enable adaptation of recent numerical schemes developed for DPDE to the SDPD setting. In this article, a Metropolis step in the integ.ation of the fluctuation/dissipation part of SDPD is introduced to improve its stability.

关键词： smoothed dissipative particle dynamics (SDPD) numerical integ.ation Metropolis alg.rithm

An effective g.ug. field theory of the nucleon interactions

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第10期76卷 76-84页

作者： eduard Boos Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State UniversityLeninskie Gory119991MoscowRussia Faculty of Physics Lomonosov Moscow State UniversityLeninskie Gory119991MoscowRussia

We discuss the possibility of constructing.an effective g.ug. field theory of the nucleon interactions based on the ideas of isotopic invariance as well as hypercharg. invariance as a local g.ug. symmetry and spontaneous breaking.of this symmetry. The constructed effective field theory predicts the structure of interactions of protons and neutrons with ρ- and σ-mesons, and with pi-mesons and photons, as well as interactions of these particles with each other. The Lag.ang.an of the theory consists of several parts involving.dimension 4 and 5 g.ug. invariant operators. Feynman rules for physical deg.ees of freedom that follow on from the Lag.ang.an define the structure of diag.ams for one-boson exchang.s between nucleons, predicting.the internucleon one-boson-exchang. potential as well as nucleon scattering.amplitudes. The rang. of applicability of the effective theory is discussed and estimates are made of the resulting.coupling.constants. The theory predicts the mass of the neutral ρ^(0)-meson to be about 1 MeV larg.r than the mass of the charg.d mesons ρ^(±). The vector ω-meson, which is a sterile particle with respect to the considered g.ug. g.oup SU_(I)(2) × U_(Y)(1), can be added to the scheme via a g.ug.-invariant operator of dimension 5, as shown in the appendix.

关键词： g.ug. invariance spontaneous symmetry breaking nucleon interactions

Investig.tion of the liquid recycle in the reactor cascade of an industrial scale ebullated bed hydrocracking.unit

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Eng.neering 2019年第2期27卷 298-304页

作者： eduard Manek Juma Haydary Institute of Chemical and Environmental Eng.neering Faculty of Chemical and Food Technology Slovak University of Technology

One of the commercial means to convert heavy oil residue is hydrocracking.in an ebullated bed. The ebullated bed reactor includes a complex g.s–liquid–solid backmixed system which attracts the attention of many scientists and research g.oups. This work is aimed at the calculation of the internal recycle flow rate and understanding.its effect on other parameters of the ebullated bed. Measured data were collected from an industrial scale residual hydrocracking.unit consisting.of a cascade of three ebullated bed reactors. A simplified block model of the ebullated bed reactors was created in Aspen Plus and fed with measured data. For reaction yield calculation, a lumped kinetic model was used. The model was verified by comparing.experimental and calculated distillation curves as well as the calculated and measured reactor inlet temperature. Influence of the feed rate on the recycle ratio(recycle to feed flow rate) was estimated. A relation between the recycle flow rate, pump pressure difference and catalyst inventory has been identified. The recycle ratio also affects the temperature g.adient along.the reactor cascade. Influence of the recycle ratio on the temperature g.adient decreased with the cascade member order.

关键词： Residual hydrocracking Ebullated bed reactor Liquid recycle Aspen Plus Simulation

Exclusive meson production at HERMES

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2010年第9期34卷 1472-1475页

作者： eduard Avetisyan Deutsches Electronen Synchrotron

The exclusive electroproduction of pseudoscalar and vector mesons was studied with the HERMES spectrometer at the DESY laboratory by scattering.27.6 g.V positron and electron beams off a transversely polarized hydrog.n *** results are compared to calculations based on g.neralized parton distributions,some of which are sensitive to the contribution of the total ang.lar momentum of the quarks to the proton spin.

关键词： exclusive meson production g.neralized parton distributions

The Investig.tion of the Dynamical Evolution of Extrasolar Three-planetary System g. 3138

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第1期22卷 68-84页

作者： Alexander Perminov eduard Kuznetsov Ural Federal University 51 Lenin AvenueYekaterinburgRussia

This article is devoted to studying.the dynamical evolution and orbital stability of compact extrasolar threeplanetary system g. 3138. In this system, all semimajor axes are less than 0.7 au. The modeling.of planetary motion is performed using.the averag.d semi-analytical motion theory of the second order in planetary masses,which the authors construct. Unknown and known with errors orbital elements vary in allowable limits to obtain a set of initial conditions. Each of these initial conditions is applied for the modeling.of planetary motion. The assumption about the stability of observed planetary systems allows to eliminate the initial conditions leading.to excessive g.owth of the orbital eccentricities and inclinations and to identify those under which these orbital elements conserve moderate values over the whole modeling.interval. Thus, it becomes possible to limit the rang. of possible values of unknown orbital elements and determine their most probable values in terms of stability.

关键词： Planetary Systems planets and satellites:dynamical evolution and stability planetstar interactions celestial mechanics