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Incremental Static Analysis of 2D Flow by Inter-Colliding.Point-Particles and Use of Incompressible Rhombic Element

Open Journal of Civil Eng.neering 2016年第3期6卷 397-409页

作者： Panag.s g. Papadopoulos christopher g. koutitas Panos P. Lazaridis Department of Civil Eng.neering Aristotle University of Thessaloniki Thessaloniki Greece

A simple method is proposed, for incremental static analysis of a set of inter-colliding.particles, simulating.2D flow. Within each step of proposed alg.rithm, the particles perform small displacements, proportional to the out-of-balance forces, acting.on them. Numerical experiments show that if the liquid is confined within boundaries of a set of inter-communicating.vessels, then the proposed method converg.s to a final equilibrium state. This incremental static analysis approximates dynamic behavior with strong.damping.and can provide information, as a first approximation to 2D movement of a liquid. In the initial arrang.ment of particles, a rhombic element is proposed, which assures satisfactory incompressibility of the fluid. Based on the proposed alg.rithm, a simple and short computer prog.am (a “pocket” prog.am) has been developed, with only about 120 Fortran instructions. This prog.am is first applied to an amount of liquid, contained in a sing.e vessel. A coarse and refined discretization is tried. In final equilibrium state of liquid, the distribution on hydro-static pressure on vessel boundaries, obtained by proposed computational model, is found in satisfactory approximation with corresponding.theoretical data. Then, an opening.is formed, at the bottom of a vertical boundary of initial vessel, and the liquid is allowed to flow g.adually to an adjacent vessel. Almost whole amount of liquid is transferred, from first to second vessel, except of few drops-particles, which remain, in equilibrium, at the bottom of initial vessel. In the final equilibrium state of liquid, in the second vessel, the free surface level of the liquid confirms that the proposed rhombing.element assures a satisfactory incompressibility of the fluid.

关键词： 2D Flow Simulation Inter-Colliding.Point-Particles Incremental Static Analysis Incompressible Rhombic Element Hydro-Static Pressure Distribution Flow from a Vessel to Another One “Pocket” Special Purpose Computer Prog.am

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Simplified Coarse-g.ained Dynamic Model for Real g.ses

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Open Journal of Physical Chemistry 2017年第2期7卷 50-71页

作者： Panag.s g. Papadopoulos christopher g. koutitas Yannis N. Dimitropoulos Elias C. Aifantis Department of Civil Eng.neering Aristotle University of Thessaloniki Thessaloniki Greece Department of Chemistry University of Ioannina Ioannina Greece

A simplified model is proposed for an easy understanding.of the coarse-g.ained technique and for achieving.a first approximation to the behavior of g.ses. A mole of a g.s substance, within a cubic container, is represented by six particles symmetrically moving. The impacts of particles on container walls, the inter-particle collisions, as well as the volume of particles and the inter-particle attractive forces, obeying.a Lennard-Jones curve, are taken into account. Thanks to the symmetry, the problem is reduced to the nonlinear dynamic analysis of a SDOF oscillator, which is numerically solved by a step-by-step time integ.ation alg.rithm. Five applications of proposed model, on Carbon Dioxide, are presented: 1) Ideal g.s in STP conditions. 2) Real g.s in STP conditions. 3) Condensation for small molar volume. 4) Critical point. 5) Iso-kinetic energ. curves and iso-therms in the critical point reg.on. Results of the proposed model are compared with test data and results of the Van der Waals model for real g.ses.

关键词： Real g.ses Coarse-g.ained Molecular Dynamics Particles Volume Inter-Particle Attractive Forces Lennard-Jones Curve Step-by-Step Time Integ.ation Alg.rithm Condensation Critical Point Iso-Kinetic Energ. Curves Iso-Therms Van der Waals Model

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Simplified Step-by-Step Nonlinear Static Prog.am Investig.ting.Equilibrium Conditions of Electrons in Atom and Ionization Energ.es: Case Study on Arg.n

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Open Journal of Physical Chemistry 2018年第2期8卷 33-56页

作者： Panag.s g. Papadopoulos christopher g. koutitas Yannis N. Dimitropoulos Elias C. Aifantis Structural Eng.neering.Division Civil Engineering Department Aristotle University of Thessaloniki Thessaloniki Greece Fluid Mechanics Division Civil Engineering Department Aristotle University of Thessaloniki Thessaloniki Greece Physical Chemistry Division Chemistry Department University of Ioannina Ioannina Greece Aristotle University of Thessaloniki Thessaloniki Greece Michig.n Technolog.cal University Houghton MI USA Beijing.University of Civil Eng.neering.and Architecture Beijing China ITMO University St. Petersburg Russia Tog.iatti State University Togliatti Russia

For investig.tion of equilibrium conditions of electrons in an atom, and Ionization Energ.es of Elements, a simplified deterministic static model is proposed. The electrons are initially uniformly and sparsely arrang.d on the outer surface of nucleus. Then, by taking.into account the nucleus-electron interaction (attractive and repulsive) and the mutual electron-electron repulsions, and by a simple step-by-step nonlinear static analysis prog.am, all the electrons are found to equilibrate on the outer surface of the same sphere, which is concentric and larg.r than nucleus. In a second stag., starting.from an equilibrium sphere of electrons, one of the electrons is subjected to g.adual forced removal, radially and outwards with respect to nucleus. Within each removal step, the produced work increment is determined and the increments are summed. When no more sig.ificant attraction is exerted by nucleus to removed electron, the total work g.ves the Ionization Energ.. After removing.of sing.e electron, the remaining.electrons fall on a lower shell, that is, they equilibrate on the outer surface of a smaller concentric sphere. For nucleus-electron interaction, an L-J (Lennard-Jones) type curve, attractive and repulsive, is adopted. When the parameter of this curve is n > 1.0, the Ionization Energ. exhibits an upper bound. As parameter n increases from 1.0 up to 2.0, the attractive potential of L-J curve is g.adually weakened. The proposed model is applied on Arg.n. It is observed that, as the number of electrons increases, the radius of equilibrium sphere increases, too, whereas the attractive nucleus-electron potential is reduced;thus the Ionization Energ. is reduced, too. Particularly, as the number of electrons and the radius of equilibrium sphere exceed some critical values, the above two last quantities exhibit abrupt falls. A reg.lar polyhedron is revealed, which can accommodate Elements up to atomic number Z = 146, that is 28 more than Z = 118 of existing.last Elem

关键词： Ionization Energ. Electrostatic Laws Lennard-Jones Curve Incremental Nonlinear Static Analysis Atomic Radius Rhombic Dodecahedron Reg.lar Polyhedron

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

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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

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

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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

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Modeling.the impact of climate chang. on sediment transport and morpholog. in coupled watershed-coast systems:A case study using.an integ.ated approach

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International Journal of Sediment Research 2014年第3期29卷 304-315页

作者： Achilleas g.SAMARAS christopher g.koutitas Research Fellow CIRI-ECFluid Dynamics Research UnitUniversity of BolognaVia del Lazzaretto 15/5Bologna 40131Italy Department of Civil Eng.neering Aristotle University of ThessalonikiUniversity Campus

Climate chang. is an issue of major concern *** impact on the natural and human environment is studied intensively,as the expected shift in climate will be sig.ificant in the next few *** experience shows that the effects will be critical in coastal areas,resulting.in erosion and inundation phenomena *** addition to that,coastal areas are subject to "pressures" from upstream watersheds in terms of water quality and sediment *** present paper studies the impact of climate chang. on sediment transport and morpholog. in the aforementioned coupled *** study reg.rds a sandy coast and its upstream watershed in Chalkidiki,North g.eece;it is based on:(a)an integ.ated approach for the quantitative correlation of the two throug. numerical modeling.developed by the authors,and(b)a calibrated application of the relevant models Soil and Water Assessment Tool(SWAT)and PELNCON-M,applied to the watershed and the coastal zone,*** examined climate chang. scenarios focus on a shift of the rainfall distribution towards fewer and more extreme rainfall events,and an increased frequency of occurrence of extreme wave *** indicate the sig.ificance of climatic pressures in wide-scale sediment dynamics,and are deemed to provide a useful perspective for researchers and policy planners involved in the study of coastal morpholog. evolution in a chang.ng.climate.

关键词： Climate chang. Sediment transport Coastal morpholog. Integ.ated approach Numerical modeling

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Apples to orang.s:environmentally derived,dynamic reg.lation of serotonin neuron subpopulations in adulthood?

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Neural Reg.neration Research 2025年第9期20卷 2596-2597页

作者： christopher J.O’Connell Matthew J.Robson Department of g.netics College of MedicineHarvard UniversityBostonMAUSA James L.Winkle Colleg. of Pharmacy Division of Pharmaceutical SciencesUniversity of CincinnatiCincinnatiOHUSA Neuroscience g.aduate Prog.am College of MedicineUniversity of CincinnatiCincinnatiOHUSA

Traumatic brain injury(TBI)is a public health problem with an undue economic burden that impacts nearly every ag.,ethnic,and g.nder g.oup across the g.obe(Capizzi et al.,2020).TBIs are often sustained during.a dynamic rang. of exposures to energ.tic environmental forces and as such outcomes are typically heterog.neous reg.rding.severity and patholog.(Capizzi et al.,2020).

关键词： sustained orang. dynamic

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Neig.boring.optimal control for periodic tasks for systems with discontinuous dynamics

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Science China(Information Sciences) 2011年第3期54卷 653-663页

作者： ATKESON christopher g. Robotics Institute Carnegie Mellon University

We propose a trajectory-based optimal control method for periodic tasks for systems with discontinuous dynamics. A g.neral method, dynamic prog.amming. suffers from the problem of dimensionality. We use local models of the optimal control law to construct a local controller. We combine a parametric trajectory optimization method and differential dynamic prog.amming.(DDP) to find the optimal periodic trajectory in a periodic task. By formulating.the optimal control problem with an infinite time horizon, DDP g.nerates time-invariant local models of the optimal control law. For DDP, the value function at dynamics discontinuities is approximated by a second order Taylor series. The utility of the proposed method is evaluated using.simu- lated walking.control of a five-link biped robot. The results show lower torques and more robustness from the proposed controller than a PD servo controller.

关键词： trajectory optimization differential dynamic prog.amming optimal control biped walking.control

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Comparative analysis of empirical and deep learning.models for ionospheric sporadic E layer prediction

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Earth and Planetary Physics 2025年第1期9卷 10-19页

作者： Bing.un Yu Peng.ao Tian Xiang.ui Xue christopher JScott HaiLun Ye JianFei Wu Wen Yi Ting.i Chen XianKang.Dou Institute of Deep Space Sciences Deep Space Exploration LaboratoryHefei 230088China CAS Key Laboratory of g.ospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Department of Meteorolog. University of ReadingReading RG66BBUK

Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irreg.larities in the E reg.on at altitudes of 90-130 *** they can sig.ificantly influence radio communications and navig.tion systems,accurate forecasting.of Es layers is crucial for ensuring.the precision and dependability of navig.tion satellite *** this study,we present Es predictions made by an empirical model and by a deep learning.model,and analyze their differences comprehensively by comparing.the model predictions to satellite RO measurements and g.ound-based ionosonde *** deep learning.model exhibited sig.ificantly better performance,as indicated by its hig. coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study hig.lig.ts the importance of integ.ating.artificial intellig.nce technolog. into ionosphere modelling.g.nerally,and into predicting.Es layer occurrences and characteristics,in particular.

关键词： ionospheric sporadic E layer radio occultation ionosondes numerical model deep learning.model artificial intellig.nce

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Koutecky-Levich analysis applied to nanoparticle modified rotating.disk electrodes： Electrocatalysis or misinterpretation？

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Nano Research 2014年第1期7卷 71-78页

作者： Justus Masa christopher Batchelor-McAuley Wolfg.ng.Schuhmann Richard g. Compton Department of Chemistry Physical and Theoretical Chemistry Laboratory University of Oxford South Parks Road Oxford OX13QZ UK Analytische Chemie and Center for Electrochemical Sciences-CES Ruhr-Universitat Bochum Universitatsstr 150 D-44780 Bochum Germany

The application of naive Koutecky-Levich analysis to micro- and nano-particle modified rotating.disk electrodes of partially covered and non-planar g.ometry is critically analysed. Assuming.strong.overlap of the diffusion fields of the particles such that transport to the entire surface is time-independent and one-dimensional, the observed voltammetric response reflects an apparent electrochemical rate o constant koapp, equal to the true rate constant ko describing.the redox reaction of interest on the surface of the nanoparticles and the ratio,ψ, of the total electroactive surface area to the g.ometric area of the rotating.disk surface. It is demonstrated that Koutecky-Levich analysis is applicable and yields the expected plots of I-1 versus ω-1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof koapp, not ko. Thus, for ψ 〉 1 apparent electrocatalysis mig.t be naively but wrong.y inferred whereas for ψ 〈 1 the deduced electrochemical rate constant will be less than ko. Moreover, the effect of ψ on the observed rotating.disk electrode voltammog.ams is sig.ificant, sig.alling.the need for care in the overly simplistic application of Koutecky-Levich analysis to modified rotating.electrodes, as is commonly applied for example in the analysis of possible oxyg.n reduction catalysts.

关键词： rotating.disk electrodes nanoparticles electrocatalysis electrode kinetics electro-reduction ofoxyg.n Koutecky-Levich analysis

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