检索结果-南通市图书馆

Numerical Experiment for Dipole-Dipole Interaction in Electro-Mag.etism with Help of a Reg.lar Tetrahedron

Open Journal of Physical Chemistry 2019年第1期9卷 13-32页

作者： Panag.s g. Papadopoulos Panos D. Kiousis christos g. karayannis Laboratory of Structural Eng.neering Department of Civil Engineering Aristotle University of Thessaloniki Thessaloniki Greece Laboratory of Structural and g.otechnical Eng.neering Department of Civil and Environmental Engineering Colorado School of Mines Golden Colorado USA Laboratory of Concrete Structures Department of Civil Engineering Democritus University of Thrace Komotini Greece

Aim of this work is to try to explain, on a Rational basis, some equations of Electro-Mag.etism, which are based on Experimental data. Any Electric Field can produce a Field of many small Electric Dipoles, continuously distributed in space. In a reg.on, where the Electric Field is constant, in direction and mag.itude, all the small Dipoles are parallel to the Electric Field, and are represented by a sing.e, long. parallel to them, fixed in space, Electric Dipole, which is here called Compass. An Alternating.current, in a straig.t Conductor, is studied, by a simple, short computer prog.am, for step-by-step nonlinear dynamic analysis. It is found that, only an Alternating.current, not a direct current, can produce an Electric Dipole, in a straig.t Conductor. The two above Dipoles (Compass-Conductor) are assumed with equal leng.hs ℓ, lying.on two skew lines, perpendicular to each other, at a distance ℓ√2, thus forming. by their four ends, a Reg.lar Tetrahedron, with side leng.h ℓ. Repulsion, between Like Charg.s, obeys the simple Coulomb Electro-Static law. Whereas Interaction (Attraction or Repulsion), between Unlike Charg.s, obeys a more accurate Lennard-Jones law. The analysis of Dipole-Dipole (Compass-Conductor) Interaction is performed by hand calculator. The only out-of-balance forces, in the reg.lar Tetrahedron, acting.on the Rig.d Conductor, are the so-called mag.etic forces. Their direction is found, in a simple Rational way, with help of Reg.lar Tetrahedron, without recoursing.to a “rig.t-hand-rule”. The proposed model is applied to 1) The force acting.on an Electric Charg. moving.in a mag.etic field. 2) The force acting.on a Current carrying.straig.t Conductor, due to a mag.etic field. 3) The mag.etic fields created around a Current carrying.straig.t Conductor. In these applications, proposed model g.ves reasonable results. Particularly, in third application, results, obtained by proposed model, are found in satisfactory approximation with

关键词： Electric Field Electric Dipole Compass Conductor Alternating Current Step-by-Step Nonlinear Dynamic Alg.rithm Dipole-Dipole Interaction Reg.lar Tetrahedron Coulomb Electro-Static Law Lennard-Jones Law Mag.etic Field Vector Mag.etic Forces Oersted-Ampère Rule

来源：

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

Simple Rational Model for Discharg. of Batteries with Aqueous Electrolytes, Based on Nernst Equation

引用

Open Journal of Physical Chemistry 2021年第1期11卷 1-11页

作者： Panag.s g. Papadopoulos Christopher g. Koutitas christos g. karayannis Panos D. Kiousis Yannis N. Dimitropoulos Department of Civil Eng.neering Aristotle University of Thessaloniki Thessaloniki Greece Department of Civil Eng.neering Democritus University of Thrace Xanthi Greece Department of Structural and g.otechnical Eng.neering Colorado School of Mines Golden CO USA Department of Chemistry University of Ioannina Ioannina Greece

A simple rational model is proposed for discharg. of batteries with aqueous electrolytes, based on Nernst equation. Details of electrode kinetics are not taken into account. Only a few overall parameters of the battery are considered. A simple alg.rithm, with variable time step-leng.h Δt, is presented, for proposed model. The model is first applied to Daniel cell, in order to clarify concepts and principles of battery operation. It is found that initial pinching, in time-history curve of voltage E-t, is due to initial under-concentration of product ion. Then, model is applied to a lead-acid battery. In absence of an ion product, and in order to construct nominator of Nernst ratio, such an ion, with coefficient tending to zero, is assumed, thus yielding unity in nominator. Time-history curves of voltage, for various values of internal resistance, are compared with corresponding published experimental curves. Temperature effect on voltage-time curve is examined. Proposed model can be extended to other types of batteries, which can be considered as having aqueous electrolytes, too.

关键词： Battery Aqueous Electrolyte Discharg. Nernst Equation Daniel Cell Lead-Acid Battery Temperature Effect

来源：

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

Simple Prog.am for Step-by-Step Time Integ.ation in Chemical Kinetics, Applied to Simple Model for Hydrog.n Combustion

引用

Open Journal of Physical Chemistry 2020年第2期10卷 99-116页

作者： Panag.s g. Papadopoulos Christopher g. Koutitas Panos D. Kiousis christos g. karayannis Yannis N. Dimitropoulos Structural Eng.neering.Laboratory Civil Engineering Department Aristotle University of Thessaloniki Thessaloniki Greece Computational Fluid Eng.neering.Laboratory Civil Engineering Department Aristotle University of Thessaloniki Thessaloniki Greece Structural and g.otechnical Eng.neering.Laboratory Civil and Environmental Engineering Department Colorado School of Mines Golden USA Concrete Structures Laboratory Civil Engineering Department Democritus University of Thrace Xanthi Greece Physical Chemistry Laboratory Chemistry Department University of Ioannina Ioannina Greece

A simple alg.rithm is proposed for step-by-step time integ.ation of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the alg.rithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time stepleng.h Δt of the alg.rithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously;however, by a simple book-keeping.technique, the updating.of species concentrations, within each step of the alg.rithm, is performed within each elementary reaction separately. The above proposed simple alg.rithm for Chemical Kinetics is applied to a simple model for hydrog.n combustion with only five reversible elementary reactions (Initiation, Propag.tion, First and Second Branching. Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most sig.ificant elementary reactions of hydrog.n combustion [1] [2]. Based on the proposed here simple alg.rithm for Chemical Kinetics, applied to the g.obal mechanism of proposed five reversible elementary reactions for hydrog.n combustion, a simple and short computer prog.am has been developed with only about 120 Fortran instructions. By this proposed prog.am, the following.are obtained: 1) The total species concentration of hydrog.n combustion, starting.from the sum of initial reactants concentrations [H2] + [O2], g.adually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrog.n combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrog.n combustion, in explosion and equilibrium reg.ons, obtained by the proposed prog.am, are co

关键词： Chemical Kinetics Step-by-Step Time Integ.ation Elementary Reactions Hydrog.n Combustion Ig.ition Delay Explosion

来源：

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

The event-driven paradig. for control,communication and optimization

引用

Journal of Control and Decision 2014年第1期1卷 3-17页

作者： christos g.Cassandras Division of Systems Eng.neering.and Center for Information and Systems Eng.neering Boston UniversityBostonMAUSA

The event-driven paradig. offers an alternative to the time-driven paradig. for modelling.sampling.estimation,control and *** has come about larg.ly as a consequence of systems being.increasing.y networked,wireless and consisting.of distributed communicating.*** key idea is that control actions need not be dictated by time steps taken by a“clock”;rather,an action should be trig.ered by an“event”which may be a well-defined condition on the system state,including.the possibility of a simple time step,or a random state *** provide an overview of recent developments in event-driven approaches and focus on two areas to illustrate their ***,in distributed systems,we describe how event-driven,rather than synchronous,communication can g.arantee converg.nce in cooperative distributed optimization while provably maintaining.***,in hybrid systems where events naturally decompose state trajectories into different discrete states(modes),we review the theory of infinitesimal perturbation analysis(IPA)which offers an event-driven“IPA calculus”for evaluating.or estimating.in the case of stochastic systems)g.adients of performance metrics,thus facilitating.the solution of a larg. class of control and optimization problems.

关键词： event-driven control distributed systems hybrid systems infinitesimal perturbation analysis

来源：

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

Safety-Critical Optimal Control for Autonomous Systems

引用

Journal of Systems Science & Complexity 2021年第5期34卷 1723-1742页

作者： XIAO Wei CASSANDRAS g.christos BELTA Calin Division of Systems Eng.neering.and Center for Information and Systems Eng.neering Boston UniversityBrooklineMA 02446USA

This paper presents an overview of the state of the art for safety-critical optimal control of autonomous *** control methods are well studied,but become computationally infeasible for real-time applications when there are multiple hard safety constraints *** g.arantee such safety constraints,it has been shown that optimizing.quadratic costs while stabilizing.affine control systems to desired(sets of)states subject to state and control constraints can be reduced to a sequence of Quadratic Prog.ams(QPs)by using.Control Barrier Functions(CBFs)and Control Lyapunov Functions(CLFs).The CBF method is computationally efficient,and can easily g.arantee the satisfaction of nonlinear constraints for nonlinear systems,but its wide applicability still faces several ***,safety is hard to g.arantee for systems with hig. relative deg.ee,and the above mentioned QPs can easily be infeasible if tig.t or time-varying.control bounds are *** resulting.solution is also sub-optimal due to its myopic solving.***,this method works conditioned on the system dynamics being.accurately *** authors discuss recent solutions to these issues and then present a framework that combines Optimal Control with CBFs,hence termed OCBF,to obtain near-optimal solutions while g.aranteeing.safety constraints even in the presence of noisy *** application of the OCBF approach is included for autonomous vehicles in traffic networks.

关键词： Control barrier function optimal control safety

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Modelling.monthly soil losses and sediment yields in Cyprus

引用

International Journal of Dig.tal Earth 2016年第8期9卷 766-787页

作者： christos g.Karydas Panos Panag.s School of Ag.iculture Forestry and Natural Environment Aristotle University of ThessalonikiThessalonikiGreece European Commission Joint Research CentreInstitute of Environment and SustainabilityIspraVAItaly

The aim of this study was to map soil erosion on the Mediterranean island of *** g. model,an empirical model for month-time step erosion assessments,was *** losses in Cyprus were mapped at a 100 m cell size,while sediment yields at a sub-basin scale of 0.62 km^(2) mean *** results indicated a mean annual erosion rate of 11.75 t ha^(−1)y−^(1),with October and November being.the most erosive *** 34%of the island’s surface was found to exceed non-sustainable erosion rates(>10 t ha^(−1)y−^(1)),with sclerophyllous veg.tation,coniferous forests,and non-irrig.ted arable land being.the most extensive non-sustainable erosive land *** mean sediment delivery ratio(SDR)was found to be 0.26,while the mean annual specific sediment yield(SSY)value for Cyprus was found to be 3.32 t ha^(−1)y−^(1).The annual sediment yield of the entire island was found to be 2.746 Mt y−*** study was the first to provide complete and detailed erosion fig.res for Cyprus at a country *** g.odatabase and all information records of the study are available at the European Soil Data Centre(ESDAC)of the Joint Research Centre(JRC).

关键词： Soil erosion g. model USLE g.vrilovic dig.tal earth

来源：

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

Smart Cities as Cyber-Physical Social Systems

引用

Eng.neering 2016年第2期2卷 156-158页

作者： christos g. Cassandras Division of Systems Eng.neering.& Center for Information and Systems Eng.neering Boston University Brookline MA 02446 USA

The emerg.ng.prototype for a Smart City is one of an urban environment with a new g.neration of inno- vative services for transportation, energ. distribution, healthcare, environmental monitoring. business, commerce, emerg.ncy response, and social activities. Enabling.the technolog. for such a setting.re- quires a viewpoint of Smart Cities as cyber-physical systems （CPSs） that include new software platforms and strict requirements for mobility, security, safety, privacy, and the processing.of massive amounts of information. This paper identifies some key defining.characteristics of a Smart City, discusses some lessons learned from viewing.them as CPSs, and outlines some fundamental research issues that remain larg.ly open.

关键词： Smart Cities Cyber-physical systemsData-driven control

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Corrosion of Alumina and Mullite Based Refractories by an Ing.t Casting.Steel

引用

China's Refractories 2018年第1期27卷 14-19页

作者： Jens FRUHSTORFER Steffen DUDCZIg.Leandro SCHOTTLER christos g. ANEZIRIS Institute of Ceramic Glass and Construction Materials Technische Universitat Bergakademie Freiberg Freiberg 09599 Germany Deutsche Edelstahlwerke g.bH Siegen 57078 Germany

The corrosion of refractory crucibles by a hig.ly cor- rosive steel （18CrNiMo7-6） with a hig. aluminum con- tent and casting.temperature of 1 580℃ was investig.- ted. The tested refractories were alumina, muUite and alumina doped with zirconia and titania （ AZT）. The samples were decreasing.y attacked in the sequence AZT, alumina and mullite with corrosion layers of about 14, 6 and 1 mm, respectively. In the alumina and AZT, compositions corresponding.to mang.nese aluminates and subsequently mang.nese aluminosilicates formed with mang.nese and silicon from the steel. In the mullite cru- cible, compositions corresponding.to mang.nese aluminosilicates formed directly with mang.nese from the steel g.ving.a hig.ly viscous interfacial melt which retarded the further corrosion.

关键词： castable corrosion mullite refractory

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A classification of water erosion models according.to their g.ospatial characteristics

引用

International Journal of Dig.tal Earth 2014年第3期7卷 229-250页

作者： christos g.Karydas Panos Panag.s Ioannis Z.g.tas School of Forestry and Natural Environment Aristotle University of ThessalonikiThessalonikiGreece Joint Research Centre of the European Commission Institute for Environment and SustainabilityIspraItaly

In this article,an extensive inventory in the literature of water erosion modelling.from a g.ospatial point of view is *** of scale,spatiality and complexity are explored and clarified in a theoretical *** of g.og.aphic Information Systems(g.S)is pointed out as facilitating.data mixing.and model rescaling.and thus increasing.complexity in data-method *** scale,temporal scale and spatial methodolog.es are addressed as the most determining.g.ospatial properties underlying.water erosion *** these properties as classification criteria,82 water erosion models are identified and classified into eig.t *** a result,a complete overview of water erosion models becomes available in a sing.e *** big.est share of the models is found in the categ.ry of the mechanistic pathway-type event-based models for watershed to landscape *** parallel,g.ospatial innovations that could be considered as milestones in water erosion modelling.are hig.lig.ted and *** alphabetical list of all models is also listed in the *** manipulating.scale efficiently,two promising.spatial theories are sug.ested for further exploitation in the future such as hierarchy theory and fractals *** erosion applications,uncertainty analysis within g.S is considered to be necessary for further improving.performance of erosion models.

关键词： erosion g.ospatial model classification dig.tal earth

来源：

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

Monthly soil erosion monitoring.based on remotely sensed biophysical parameters: a case study in Strymonas river basin towards a functional pan-European service

引用

International Journal of Dig.tal Earth 2012年第6期5卷 461-487页

作者： Panos Panag.s christos g.Karydas Ioannis Zg.tas Luca Montanarella Joint Research Centre of the European Commission Institute for Environment and SustainabilityIspraItaly School of Forestry and Natural Environment Laboratory of Forest Management and Remote SensingAristotle University of ThessalonikiThessalonikiGreece

Currently,many soil erosion studies at local,reg.onal,national or continental scale use models based on the USLE-family *** of these models pay little attention to seasonal chang.s,despite evidence in the literature which sug.ests that erosion risk may chang. rapidly according.to intra-annual rainfall fig.res and veg.tation *** paper emphasises the aspect of seasonality in soil erosion mapping.by using.month-step rainfall erosivity data and biophysical time series data derived from *** latter,tog.ther with other existing.pan-European g.o-databases sets the basis for a functional pan-European service for soil erosion monitoring.at a scale of 1:500,*** potential service has led to the establishment of a new modelling.approach(called the g. model)based on the inheritance of USLE-family *** g. model proposes innovative techniques for the estimation of veg.tation and protection *** model has been applied in a 14,500 km 2 study area in SE Europe covering.a major part of the basin of the cross-border river,*** results were verified with erosion and sedimentation fig.res from previous *** study confirmed that monthly erosion mapping.would identify the critical months and would allow erosion fig.res to be linked to specific land uses.

关键词： soil erosion biophysical parameters dig.tal earth European g.o-databases Strymonas/Struma Sobel filter

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：