检索结果-南通市图书馆

Chinese Physics B 2012年第11期21卷 144-153页

作者： m.j.Park O.m.Kwon ju H.Park S.m.Lee E.j.Cha School of Electrical Engineering Chungbuk National University Department of Electrical Engineering Yeungnam University School of Electronic Engineering Daegu University Department of Biomedical Engineering School of MedicineChungbuk National University

We consider multi-agent systems with time-varying delays and switching interconnection topologies. By con- structing a suitable Lyapunov-Krasovskii functional and using the reciprocally convex approach, new delay-dependent consensus criteria for the systems are established in terms of linear matrix inequalities （LmIs）, which can be easily solved by using various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed methods.

关键词： consensus multi-agent systems time delay Lyapunov method

ENERGY ESTImATES FOR DELAY DIFFUSION-REACTION EQUATIONS

在线全文

学校读者我要写书评

暂无评论

journal of Computational mathematics 2008年第4期26卷 536-553页

作者： j.A.Ferreira P.m.daSilva CmUC-Departamento Departamento

In this paper we consider nonlinear delay diffusion-reaction equations with initial and Dirichlet boundary conditions. The behaviour and the stability of the solution of such initial boundary value problems （IBVPs） are studied using the energy method. Simple numerical methods are considered for the computation of numerical approximations to the solution of the nonlinear IBVPs. Using the discrete energy method we study the stability and convergence of the numerical approximations. Numerical experiments are carried out to illustrate our theoretical results.

关键词： Delay diffusion reaction equation Energy method Stability Convergence.

Reservoir stress path and induced seismic anisotropy： results from linking coupled fluid-flow/geomechanical simulation with seismic modelling

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2016年第4期13卷 669-684页

作者： D.A.Angus Q.j.Fisher j.m.Segura j.P.Verdon j.-m.Kendall m.Dutko A.j.L.Crook School of Earth and Environment University of LeedsLeeds UK Formerly School of Earth and Environment University of Leeds Leeds UK Department of Earth Sciences University of Bristol BristolUK Rockfield Software Ltd. Swansea UK Three Cliffs Geomechanics Swansea UK Repsol Madrid Spain ESG Solutions Kingston Canada

We present a workflow linking coupled fluid-flow and geomechanical simulation with seismic modelling to predict seismic anisotropy induced by non-hydrostatic stress changes. We generate seismic models from coupled simulations to examine the relationship between reservoir geometry, stress path and seismic anisotropy. The results indicate that geometry influences the evolution of stress,which leads to stress-induced seismic anisotropy. Although stress anisotropy is high for the small reservoir, the effect of stress arching and the ability of the side-burden to support the excess load limit the overall change in effective stress and hence seismic anisotropy. For the extensive reservoir, stress anisotropy and induced seismic anisotropy are high. The extensive and elongate reservoirs experience significant compaction, where the inefficiency of the developed stress arching in the side-burden cannot support the excess *** elongate reservoir displays significant stress asymmetry,with seismic anisotropy developing predominantly along the long-edge of the reservoir. We show that the link betweenstress path parameters and seismic anisotropy is complex,where the anisotropic symmetry is controlled not only by model geometry but also the nonlinear rock physics model used. Nevertheless, a workflow has been developed to model seismic anisotropy induced by non-hydrostatic stress changes, allowing field observations of anisotropy to be linked with geomechanical models.

关键词： Coupled fluid-flow/geomechanics Reservoir characterization Seismic anisotropy Stress path

Nonlinear static and dynamic responses of an electrically actuated viscoelastic microbeam

在线全文

学校读者我要写书评

暂无评论

Acta mechanica Sinica 2009年第2期25卷 211-218页

作者： Y.m.Fu j.Zhang College of mechanics and Aerospace Hunan University

On the basis of the Euler-Bernoulli hypothesis, nonlinear static and dynamic responses of a viscoelastic microbeam under two kinds of electric forces [a purely direct current （DC） and a combined current composed of a DC and an alternating current] are studied. By using Taylor series expansion, a governing equation of nonlinear integro-differential type is derived, and numerical analyses are performed. When a purely DC is applied, there exist an instantaneous pull-in voltage and a durable pull-in voltage of which the physical meanings are also given, whereas under an applied combined current, the effect of the element relaxation coefficient on the dynamic pull-in phenomenon is observed where the largest Lyapunov exponent is taken as a criterion for the dynamic pull-in instability of viscoelastic microbeams.

关键词： mEmS Viscoelastic microbeam Nonlineardynamics

Optimization of mechanical and Wear Properties of Functionally Graded Al6061/SiC Nanocomposites Produced by Friction Stir Processing(FSP)

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2015年第5期28卷 584-590页

作者： m.Saadatmand j.Aghazadeh mohandesi Department of mining and metallurgical Engineering Amir Kabir University of Technology

The objective of present work is to apply the friction stir processing （FSP） to fabricate functionally graded SiC particulate reinforced Al6061 composite and investigate the effect of SiC particle mass fraction distribution on the mechanical properties and wear behavior ofAl6061/SiC composite. Regarding the obtained results in this work, with increasing SiC mass fraction, elongation decreased, but hardness enhanced. However, the optimized functionally graded composite with the highest tensile strength and wear resistance was achieved for composite with 10 wt% surface SiC. Also, the results showed that wear resistance and tensile strength decreased for composite with 13 wt% surface SiC, due to reinforcement particle clustering depending on high SiC mass fraction.

关键词： Functionally graded composite Wear mechanical properties Friction stir processing (FSP)

microstructures in a carburized steel after isothermal pearlitic treatment

在线全文

学校读者我要写书评

暂无评论

journal of materials Science & Technology 2023年第29期160卷 66-75页

作者： j.Abraham mathews H.Farahani j.Sietsma R.H.Petrov m.G.mecozzi m.j.Santofimia Department of materials Science and Engineering Delft University of TechnologyMekelweg 22628 CDDelftThe Netherlands Tata Steel Research&Development IJmuidenThe Netherlands Department of Electromechanical Systems and Metal EngineeringGhent UniversityTech Lane Ghent Science park-Campus A ZwijnaardeTechnologiepark 46Belgium

The influence of carbon concentration variations on pearlite formation(20 h at 600℃)in a case-carburized steel is *** resultant microstructure shows three distinct regions:carburized case,a transition region,and the original *** microstructural transition from the case to the core regions is observed to be relatively *** investigated region of the carburized case(0.9 wt.%C)con-tains two types of pearlite:ferrite+cementite and ferrite+m_(23)C_(6),where the pearlitic aggregate with m_(23)C_(6)shows faster formation *** kinetics of pearlite formation in the transition region(0.3 wt.%C)is very slow and is observed with only m_(23)C_(6)*** around 40%austenite decomposes into pearlite in the transition region,which,in comparison to the carburized case region of 0.9 wt.%C is a fraction that is lower by a factor of *** is absent in the investigated core region(0.16 wt.%C).The microstructure in this region is predominantly martensite and pro-eutectoid ferrite,with a fraction of ferrite well below the equilibrium *** formation in this region is limited by the redistribution of mainly Ni,mn,and Cr,and their resulting solute drag effect on the austenite/ferrite interface.A ther-modynamic and kinetic argumentation of these observations is provided with the help of thermodynamic data,precipitation simulations,and a general mixed-mode Gibbs energy balance model.

关键词： Pearlite formation Carburized steel m 2_(3)C_(6)carbide Kinetics Solute drag

mg-Al Alloys manufactured by Casting and Hot Working Process

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

journal of materials Science & Technology 2008年第1期24卷 96-98页

作者： j.m.Kim j.H.jun W.j.jung Department of Applied materials Eng. Hanbat National University Daejeon 305-719 Korea Light materials Team Korea Institute of Industrial Technology Incheon 406-800 Korea

mechanical properties of mg-Al based alloys at different fabrication state,namely as-cast,hot rolled,and annealed,were investigated to develop the alloys that are suitable for the casting/hot working ***- imental results indicated that the castability such as hot cracking resistance tends to improve with increasing the aluminum ***,the elongation at elevated temperatures was observed to decrease as the AI content increases,implying difficulties in hot forming.A small amount of Zr additions could significantly enhance the room temperature mechanical properties of hot-rolled mg-6%Al-1%Zn *** tendency of remarkable grain coarsening at high temperatures was effectively reduced by the Zr *** analyses suggested that very fine Al-3Zr precipitates formed in the Zr-added alloy are responsible for the obtained results.

关键词： magnesium Casting Forming Tensile properties

New opportunities and challenges in surveying underground cavities using photogrammetric methods

在线全文

学校读者我要写书评

暂无评论

International journal of mining Science and Technology 2021年第1期31卷 9-13页

作者： malte j.m.Gurgel Axel Preusse Institute for mine Surveying Mining Subsidence Engineering and Geophysics in MiningRWTH Aachen UniversityAachen 52062Germany

The exploitation of the underground is currently undergoing a major transformation *** mining,alternative ways of utilization are playing an increasingly important *** alternative utilizations include the storage of gases,the disposal of radioactive wastes,and the implementation of geothermal storage *** addition,more and more mining operations are being shut down,like the German hard coal mining industry in *** the integrity of closed mines must be ensured in the post-mining *** order to capture such large and complex structures efficiently and reliably,new surveying techniques are required.A promising approach is the use of photogrammetric methods to generate three-dimensional models of the *** is currently known mainly from aerial *** is conceivable to use such methods for underground *** recent years,significant progress has been made in the algorithm-based orientation of unstructured image *** powerful computer systems and the growing range of unmanned aerial vehicles could enable partially automated ***,a number of problems have to be solved for underground imaging *** exposure conditions complicate image ***,the models must be integrated into existing surveying systems with a sufficiently high degree of *** order to consider the numerous technical aspects,the development of an integrated capture and evaluation approach is *** could make an important contribution to the monitoring of critical cavities of different *** an approach would also fit into the current digitization trend in the mining industry and provide new opportunities for ground control in particular.

关键词： Photogrammetry Surveying Subsurface spatial planning

Treating amyotrophic lateral sclerosis with allogeneic Schwann cell-derived exosomal vesicles: a case report

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第4期20卷 1207-1216页

作者： Pascal j.Goldschmidt-Clermont Aisha Khan George jimsheleishvili Patricia Graham Adriana Brooks Risset Silvera Alexander j.P.Goldschmidt Damien D.Pearse W.Dalton Dietrich Allan D.Levi james D.Guest miller School of medicine University of MiamiMiamiFLUSA Stem Cell Institute Miller School of MedicineUniversity of MiamiMiamiFLUSA The miami Project to Cure Paralysis Miller School of MedicineUniversity of MiamiMiamiFLUSA Alzady International LLC MiamiFLUSA Neurological Surgery Miller School of MedicineUniversity of MiamiMiamiFLUSA

Schwann cells are essential for the maintenance and function of motor neurons,axonal networks,and the neuromuscular *** amyotrophic lateral sclerosis,where motor neuron function is progressively lost,Schwann cell function may also be ***,important signaling and potential trophic activities of Schwann cell-derived exosomal vesicles have been *** case report describes the treatment of a patient with advanced amyotrophic lateral sclerosis using serial intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles,marking,to our knowledge,the first instance of such *** 81-year-old male patient presented with a 1.5-year history of rapidly progressive amyotrophic lateral *** initial diagnosis,the patient underwent a combination of generic riluzole,sodium phenylbutyrate for the treatment of amyotrophic lateral sclerosis,and *** patient volunteered to participate in an FDA-approved single-patient expanded access treatment and received weekly intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles to potentially restore impaired Schwann cell and motor neuron *** confirmed that cultured Schwann cells obtained from the amyotrophic lateral sclerosis patient via sural nerve biopsy appeared impaired(senescent)and that exposure of the patient’s Schwann cells to allogeneic Schwann cell-derived exosomal vesicles,cultured expanded from a cadaver donor improved their growth capacity in *** a period of observation lasting 10 weeks,during which amyotrophic lateral sclerosis Functional Rating Scale-Revised and pulmonary function were regularly monitored,the patient received weekly consecutive infusions of 1.54×1012(×2),and then consecutive infusions of 7.5×1012(×6)allogeneic Schwann cell-derived exosomal vesicles diluted in 40 mL of Dulbecco’s phosphate-buffered *** of the infusions were associated with adverse events such as infusion reactions(allergic or otherwise)or

关键词： allogeneic amyotrophic lateral sclerosis exosomes infusion neuromuscular junction Schwann cell

Conforming Hierarchical Basis Functions

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2012年第9期12卷 1215-1256页

作者： m.j.Bluck Department of mechanical Engineering Imperial CollegeLondonSW72AZUK

A unified process for the construction of hierarchical conforming bases on a range of element types is proposed based on an ab initio preservation of the underlying *** process supports not only the most common simplicial element types,as are now well known,but is generalized to squares,hexahedra,prisms and importantly *** these latter cases have received(to varying degrees)attention in the literature,their foundation is less well developed than for the simplicial *** generalization discussed in this paper is effected by recourse to basic ideas from algebraic topology(differential forms,homology,cohomology,etc)and as such extends the fundamental theoretical framework established by the work of Hiptmair[16-18]and Arnold et al.[4]for *** process of forming hierarchical bases involves a recursive orthogonalization and it is shown that the resulting finite element mass,quasi-stiffness and composite matrices exhibit exponential or better growth in condition number.

关键词： Finite elements vector basis functions differential forms