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Frontiers of Structural and Civil Engineering 2018年第1期12卷 109-124页

作者： ricardo MONTEIRO Miguel ARAUJO Raimundo DELGADO Mario o MARQUES School of Advanced Studies IUSS Pavia Italy Department of Civil Engineering Faculty of Engineering University of Porto Portugal

The increasing awareness of the general society toward the seismic safety of structures has led to more restrictive performance requirements hence, many times, to the need of using new and more accurate methods of analysis of structures. Among these, nonlinear static procedures are becoming, evermore, the preferred choice of the majority of design codes, as an alternative to complete nonlinear time-history analysis for seismic design and assessment of structures. The many available software tools should therefore be evaluated and well understood, in order to be easily and soundly employed by the practitioners. The study presented herein intends to contribute to this need by providing further insight with respect to the use of commonly employed structural analysis software tools in nonlinear analysis of bridge structures. A comparison between different nonlinear modeling assumptions is presented, together with the comparison with real experimental results. Furthermore, alternative adaptive pushover procedures are proposed and applied to a case study bridge, based on a generic plastic hinge model. The adopted structural analysis program proved to be accurate, yielding reliable estimates, both in terms of local plastic hinge behavior and global structural behavior.

关键词： nonlinear analysis pushover RC bridges structural modelling software

Expansion Planning for Renewable Integration in Power System of Regions with Very High Solar Irradiation

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Journal of Modern Power Systems and Clean Energy 2021年第3期9卷 485-494页

作者： Musfer Alraddadi Antonio J.Conejo ricardo M.Lima the Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOH 43210USA the Department of Integrated Systems Engineering and the Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOH 43210USA King Abdullah University of Science and Technology Thuwal 23955-6900Kingdom of Saudi Arabia

In this paper,we address the long-term generation and transmission expansion planning for power systems of regions with very high solar *** target the power systems that currently rely mainly on thermal generators and that aim to adopt high shares of renewable *** propose a stochastic programming model with expansion alternatives including transmission lines,solar power plants(photovoltaic and concentrated solar),wind farms,energy storage,and flexible combined cycle gas *** model represents the longterm uncertainty to characterize the demand growth,and the short-term uncertainty to characterize daily solar,wind,and demand *** use the Saudi Arabian power system to illustrate the functioning of the proposed model for several cases with different renewable integration *** results show that a strong dependence on solar power for high shares of renewable sources requires high generation capacity and storage to meet the night demand.

关键词： Generation and transmission expansion planning uncertainty solar power wind power

A Novel Iterative Velocity Control Algorithm and Its FPGA Implementation Based on Trigonometric Function

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Chinese Journal of Electronics 2019年第2期28卷 237-245页

作者： WEN Quangang LIANG Yanchun Adriano Tavares ricardo Teixeira WU Chunguo Key Laboratory of Symbol Computation and Knowledge Engineering of Ministry of Education College of Computer Science and Technology Jilin University Zhuhai Laboratory of Key Laboratory of Symbol Computation and Knowledge Engineering of Ministry of Education Zhuhai College of Jilin University Department of Industrial Electronics University of Minho Campus de Azurm

The servo motor’s flexible acceleration/deceleration(acc/dec) control is an emerging research topic in the automation field. A velocity control algorithm based on trigonometric function is proposed in this *** required parameters, it transforms trigonometric calculations into elementary mathematical operations and calculates the velocity controlling values iteratively, which could avoid trigonometric calculation and reduce the computation time. Experimental results show that the proposed algorithm is suitable for implementation on field programmable gate arrays and achieves a flexible controlling, enhancing both the equipment’s stability and reliability. It is promising to significantly improve the high-speed computerized numerical control equipment’s controlling accuracy, without a huge hardware resource consumption.

关键词： Acceleration Velocity control Algorithm design and analysis Field programmable gate arrays Servomotors

A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field for fixed boundary equilibria

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Plasma Science and Technology 2024年第11期26卷 65-70页

作者： ricardo FARENGO Pablo L GARCÍA-MARTÍNEZ Hugo E FERRARI Centro Atómico Bariloche Comisión Nacional de Energía AtómicaBariloche 8400Argentina Instituto Balseiro Universidad Nacional de CuyoBariloche 8400Argentina CONICET CCT-Patagonia Norte Bariloche 8400Argentina

A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field consistent with a given internal magnetohydrodynamic(MHD) equilibrium and coil geometry is presented. The constrained optimization technique employed allows to fix the exact position of the X-points. The external poloidal flux and field are calculated using Green's functions expressed in terms of elliptic integrals that are calculated using a fast and accurate *** calculation can be limited to the region between the plasma and the device wall. An example for a double null configuration is presented.

关键词： MHD equilibrium Green's functions tokamak

Local Stability Analysis of a Curzon-Ahlborn Engine without Ideal Gas Working at the Maximum Ecological Regime

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Journal of Energy and Power Engineering 2013年第5期7卷 928-936页

作者： ricardo Paiez Hernandez Delfino Ladino Luna Pedro Portillo Diaz Marco A Barranco jimenez Irreversible Processes Physics Research Group Basic Sciences Department Metropolitan Autonomous University CampusAzcapotzalco Distrito Federal 02200 Mdxico Basic Sciences Department Metropolitan Autonomous University Campus Azcapotzalco Distrito Federal 02200 M~xico Information Technology School of the National Polytechnic Institute Distrito Federal 07738 Mexico

In this work, the stability of an endoreversible Curzon-Ahlbom engine is analyzed, using Van der Waals gas as a working substance and the corresponding efficiency for this engine working at temperatures withinthe maximum ecological regime. By mean s of a local stability analysis we find that a critical point of an almost linear system is stable andanalytically expressed in eigenvalues. After an arbitrarily small perturbation, the system state exponentially decays to a critical point, with either of two characteristic relaxation times, which are a function of the thermal conductance （a）, heat capacity （C） and T=T2/T1. The behavior of relaxation times and solution of the systems are qualitatively shown by sketching its phase portrait, which results susceptible to operating regimes, i.e., the eigenvectors in the maximum ecological regime have a clockwise rotation with respect to the eigenvectors in the regime of maximumpower. Finally, it has to observe that afterto λvw = 1, approximation,ηVWE=4^-3ηC is obtained, where ηVWE is the Van der Waals efficiency atrnaximum ecological regime and r/c is Carnot＇s efficiency. Finally, it discussed the local stability and steady state of the energetic properties of the endoreversible engine.

关键词： Ecological regime dynamics Van der Waals equation stability steady state.

An Explicit Formula for Two-Dimensional Singly-Periodic Regularized Stokeslets Flow Bounded by a Plane Wall

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Communications in Computational Physics 2018年第1期23卷 142-167页

作者： Forest O.Mannan ricardo Cortez Department of Mathematics Tulane UniversityNew OrleansLouisiana 70118-5665USA

We derive a closed form expression for the regularized Stokeslet in two space dimensions with periodic boundary conditions in the x-direction and a solid plane wall at y=*** accommodate the no-slip condition on the wall,a system of images for the regularized Stokeslets was *** periodicity is enforced by writing all elements of the image system in terms of a Green’s function whose periodic extension is *** the formulation is derived in the context of regularized Stokeslets,the expression for the traditional(singular)Stokeslet is easily found by taking the limit as the regularization parameter approaches *** new formulation is validated by comparing results of two test problems:the Taylor infinite waving sheet and the motion of a cylinder moving near a *** an example of an application,we use our formulation to compute the motion and flow generated by cilia using a model that does not prescribe the motion so that the beat period and synchronization of neighboring cilia are a result of the forces developed along the cilia.

关键词： Regularized Stokeslets singly-periodic flow method of images

Lagrangian Mesh Model with Regridding for Planar Poiseuille Flow

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Communications in Computational Physics 2017年第6期22卷 112-132页

作者： Jingxuan Zhuo ricardo Cortez Robert Dillon Department of Mathematics and Statistics Washington State UniversityUSA Department of Mathematics Tulane UniversityUSA

Many biological settings involve complex fluids that have non-Newtonian mechanical responses that arise from suspended *** contrast,Newtonian fluids are liquids or mixtures of a simple molecular structure that exhibit a linear relationship between the shear stress and the rate of *** modeling complex fluids,the extra stress from the non-Newtonian contribution must be included in the governing *** this study we compare Lagrangian mesh and Oldroyd-B formulations of fluidstructure interaction in an immersed boundary *** start-up phase of planar Poiseuille flow between two parallel plates is used as a test case for the fluid *** Newtonian and Oldroyd-B fluids there exist analytical solutions which are used in the comparison of simulation and theoretical *** Lagrangian mesh results are compared with Oldroyd-B using comparable parameters.A regridding algorithm is introduced for the Lagrangian mesh *** show that the Lagrangian mesh model simulations with regridding produce results in close agreement with the Oldfoyd-B model.

关键词： Lagrangian mesh model Oldroyd-B immersed boundary method viscoelastic fluid regridding methods

Effects of meal size and proximal-distal segmentation on gastric activity

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World Journal of Gastroenterology 2010年第46期16卷 5861-5868页

作者： Madileine F Américo Marjorie V Ietsugu Fernando G Romeiro Luciana A Corá ricardo B Oliveira José ricardo A Miranda Department of Physics and Biophysics IBBUNESP-Sao Paulo State University Institute of Biological Sciences and Health ICBSUFMT-University of Mato Grosso Department of Clinical Medicine FMBUNESP-Sao Paulo State University Department of Clinical Medicine FMRPUSP-University of So Paulo UNCISAL-Alagoas State University of Health Sciences

AIM:To evaluate the effects of meal size and three segmentations on intragastric distribution of the meal and gastric motility,by ***:Twelve healthy volunteers were randomly assessed,twice,by *** test meal consisted of 60 or 180 mL of yogurt labeled with 64 MBq 99m Tc-tin *** and posterior dynamic frames were simultaneously acquired for 18 min and all data were analyzed in *** proximal-distal segmentations using regions of interest were adopted for both ***:Intragastric distribution of the meal between the proximal and distal compartments was strongly influenced by the way in which the stomach was divided,showing greater proximal retention after the 180 *** important finding was that both dominant frequencies (1 and 3 cpm) were simultaneously recorded in the proximal and distal stomach;however,the power ratio of those dominant frequencies varied in agreement with the segmentation adopted and was independent of the meal ***:It was possible to simultaneously evaluate the static intragastric distribution and phasic contractility from the same recording using our scintigraphic approach.

关键词： Gastric motility Phasic contractions Proximal stomach Scintigraphy Meal size

Novel suturing technique,based on physical principles,achieves a breaking point double that obtained by conventional techniques

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World Journal of Gastrointestinal Surgery 2021年第9期13卷 1039-1049页

作者： Francisco Javier Pérez Lara Rogelio Zubizarreta jimenez Francisco Javier Moya Donoso Jose Manuel Hernández Gonzalez Tatiana Prieto-Puga Arjona ricardo Marín Moya Maria Pitarch Martinez Department of Surgery Hopital de AntequeraMalaga 29200Spain DOXA Malaga 29730Spain

BACKGROUND Sutures have been used to repair wounds since ancient ***,the basic suture technique has not significantly *** Phase I of our project,we proposed a“double diabolo”suture design,using a theoretical physical study to show that this suture receives 50%less tension than conventional sutures,and so a correspondingly greater force must be applied to break *** To determine whether these theoretical levels of resistance were met by the new type of *** An observational study was performed to compare three types of sutures,using a device that exerted force on the suture until the breaking point was *** tension produced by this traction was *** following variables were considered:Tearing stress on entry/exit points,edge separation stress,and suture break *** study sample consisted of 30 sutures with simple interrupted stitches(Group 1),30 with continuous stitches(Group 2),and 30 with the“double diabolo”design(Group 3).RESULTS The mean degree of force required to reach the breaking point for each of these variables(tearing,separation,and final breaking)was highest in Group 3(14.56,18.28,and 21.39 kg),followed by Group 1(7.36,10.38,and 12.81 kg)and Group 2(5.77,7.7,and 8.71 kg).These differences were statistically significant(P<0.001)in all *** The experimental results show that with the“double diabolo”suture,compared with conventional sutures,greater force must be applied to reach the breaking point(almost twice as much as in the simple interrupted suture and more than double that required for the continuous suture).If these results are confirmed in Phase III(the clinical phase)of our study,we believe the double diabolo technique should be adopted as the standard approach,especially when the suture must withstand significant tension(e.g.,laparotomy closure,thoracotomy closure,diaphragm suture,or hernial orifice closure).

关键词： Suture Technique Physical principles Tension

Adaptive Control for Passive Kinesiotherapy ELLTIO

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Journal of Bionic Engineering 2014年第4期11卷 581-588页

作者： ricardo López Hipólito Aguilar Sergio Salazar Rogelio Lozano Laboratory UMI LAFMIA 3175 CINVESTAV-CNRS Móxico D. F. CNRS Research Director Universitb de Technologie de Compiègne 60200 Compiègne France

Exoskeletons are mechatronic devices used to increase human muscle strength and resistance. In the last decade these devices have become a very useful tool to assist active kinesiotherapy. This paper presents the design of exoskeleton focused on the rehabilitation of ankle and knee for the right leg. The construction of prototype like Exoskeleton for Lower Limb Training with Instrumented Orthoses （ELLTIO） using Series Elastic Actuator （SEA） to reduce the effort in the human joints, and a control law to perform a rehabilitation routine using an adaptive control scheme were first implemented in simulation to verify the control strategy and make a real rehabilitation test. The adaptive control law is proposed with the intention that the exoskeleton can adapt to user parameters at the time when performing the exercise. The results show the parameters estimation and tracking trajectory for the exoskeleton were proposed, and this trajectory could be a routine rehabilitation proposed by the therapist.

关键词： exoskeleton parametric identification rehabilitation robotics adaptive control.