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A Robust MPP Tracker Based on sliding Mode Control for a Photovoltaic Based Pumping system

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International journal of Automation and computing 2017年第4期14卷 489-500页

作者： Farhat Maissa oscar Barambones sbita Lassad Aymen Fleh department of Electrical Electronics and Communications Engineering American University of Ras A1 Khaimah Ras AI Khaimah 10021 UAE Advanced Control Group Faculty of Engineering of Vitoria-Gasteiz University of the Basque Country Bilbao Spain Electrical and Automatic Engineering department Engineering School of Gabes University of Gabes Zrig Gabes 6029 Tunisia

In this paper, a mathematical model of the photovoltaic （PV） pumping system＇s main components is firstly established. Then, the design of maximum power point tracking （MPPT） stage that ensures battery charging is described. This work is motivated by the need of photovoltaic generator （PVG） that efficiently extracts maximum power. The PVG is a special source of energy which has nonlinear current-voltage characteristics depending on variations in temperature and solar irradiance. In order to achieve the MPPT operating goals, a special interest is focused on the variable structure sliding mode （sM） control strategy and the classic perturb and observe （P＆O） algorithm. The permanent magnet synchronous motor （PMsM） is selected as a pump driver. The field oriented control is performed as the motor drive strategy. simulation results show a high level of efficiency, obtained with the proposed PV based pumping system. The performance comparison between sM controller and P＆O controller has been carried out to demonstrate the effectiveness of the former in drawing more energy and a fast response against irradiation disturbances.

关键词： Photovoltaic (PV) pump storage battery boost sliding mode control (sMC) maximum power point tracking (MPPT).

Hierarchical dispatch of multiple microgrids using nodal price:an approach from consensus and replicator dynamics

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journal of Modern Power systems and Clean Energy 2019年第6期7卷 1573-1584页

作者： Miguel A.VELAsQUEZ oscar TORREs-PEREZ Nicanor QUIJANO Angela CAdeNA department of Electrical and Electronics Engineering Universidad de los AndesBogotaColombia

A hierarchical approach for the energy management of geographically close microgrids connected through a dedicated AC power network is proposed in this *** proposed approach consists of a two-layer energy management system(EMs)for networked *** the lower layer,each micro grid solves its own economic dispatch problem through a distributed model predictive control approach that respects capacity limits and ramp-rate constraints of distributed *** the upper layer,the energy trading in the network of microgrids decides how to optimally trade the energy based on the marginal cost information from the lower layer in order to improve global optimization objectives,e.g.,social *** order to solve the trading problem,a consensusbased algorithm and a replicator dynamics algorithm are proposed assuming that the marginal cost function of the microgrid is known and *** is shown that both algorithms converge to the same solution,which is equivalent to the minimization of operation *** consensus-based algorithm is extended in order to tackle more general marginal cost functions and trading network ***,the effect of ramp constraints and network limits is *** show the effectiveness of the proposed algorithms for three interconnected microgrids with different characteristics.

关键词： Consensus Economic dispatch Hierarchical control Networked microgrids Ramp limits Replicator dynamics

Data model extension for security event notification with dynamic risk assessment purpose

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science China(Information sciences) 2013年第11期56卷 36-44页

作者： David LOPEZ oscar PAsTOR Luis Javier GARCIA VILLALBA Group of Analysis Security and Systems (GASS) Department of Software Engineering and Artificial Intelligence (DISIA) School of Computer Science Universidad Complutense Madrid 28040 Spain

Dynamic risk assessment refers to a risk management framework where frequent updates of risk evaluation information are used to evaluate risk exposure,as close as possible to *** this paper,we present the incident object description exchange format extended model for dynamic risk *** format attempts to overcome the absence of integration and real-time communication between security systems and risk assessment *** model is based on the incident object definition exchange format,which is commonly used in the computer security incident response teams *** data model aims to facilitate a global vision of information systems risk by supplying real-time security events data to risk assessment tools based on renowned *** present a proof-of-concept scenario to demonstrate the usefulness of this integration and the proposed data model,and discuss the expected improvements.

关键词： dynamic risk assessment risk management DRA IOdeF-DRA IOdeF.

Correlation analysis among vorticity,Q method and Liutex

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journal of Hydrodynamics 2020年第6期32卷 1207-1211页

作者： Yifei Yu Pushpa shrestha oscar Alvarez Charles Nottage Chaoqun Liu department of Mathematics the University of Texas at ArlingtonArlington76019USA

Influenced by the fact that vorticity represents rotation for rigid body,people believe this idea also works for fluid ***,the vortex predictions by vorticity do not match experimental results,which drove scientists to look for more appropriate methods to identify *** vortex identification methods can be categorized into three *** vorticity-based method is classified as the first *** relying on eigenvalues of velocity gradient tensor are considered as the second *** still believe vorticity is vortex since vorticity theory looks correct in mathematics,but all other methods are only scalars and unable to indicate the swirl ***,a new vortex identification method called Liutex is *** is regarded as the third-generation method,not only overcoming all previous methods’drawbacks but also having a clear physical *** direction of Liutex represents the swirl axis of rotation,and its strength is equal to twice the angular *** this paper,we did a correlation analysis between vorticity,Q,λ_(ci),λ_(2)methods and Liutex based on a direct numerical simulation(DNs)case of boundary layer *** results show that the correlation between vorticity and Liutex is very small or even negative in strong shear regions,which demonstrates that using vorticity to detect vortex lacks scientific foundation and vorticity is not appropriate to represent *** correlation analysis also shows that the second generation is contaminated too by shear and thus is not accurate to identify the vortex structure.

关键词： Correlation Liutex vorticity Q method λ_(ci)method λ_(2)method

Application of a biochemical and clinical model to predict individual survival in patients with end-stage liver disease

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World journal of Gastroenterology 2009年第22期15卷 2768-2777页

作者： Eduardo Vilar Gomez Luis Calzadilla Bertot Bienvenido Gra Oramas Enrique Arus soler Raimundo Llanio Navarro Javier Diaz Elias oscar Villa Jiménez maria del Rosario Abreu Vazquez department of Hepatology National Institute of Gastroenterology department of Pathology National Institute of Gastroenterology department of Gastroenterology National Institute of Gastroenterology deparment of Gastroenterology The"Calixto Garcia"Hospital department of Biostatistics National Institute of Gastroenterology

AIM:To investigate the capability of a biochemical and clinical model,BioCliM,in predicting the survival of cirrhotic ***:We prospectively evaluated the survival of 172 cirrhotic *** model was constructed using clinical(ascites,encephalopathy and variceal bleeding) and biochemical(serum creatinine and serum total bilirubin) variables that were selected from a Cox proportional hazards *** was applied to estimate 12-,52-and 104-wk *** model's calibration using the Hosmer-Lemeshow statistic was computed at 104 wk in a validation ***,the model's validity was tested among an independent set of 85 patients who were stratified into 2 risk groups(low risk≤8 and high risk>8).REsULTs:In the validation cohort,all measures of fi t,discrimination and calibration were improved when the biochemical and clinical model was *** proposed model had better predictive values(c-statistic:0.90,0.91,0.91) than the Model for End-stage Liver Disease(MELD) and Child-Pugh(CP) scores for 12-,52-and 104-wk mortality,*** addition,the Hosmer-Lemeshow(H-L) statistic revealed that the biochemical and clinical model(H-L,4.69) is better calibrated than MELD(H-L,17.06) and CP(H-L,14.23).There were no significant differences between the observed and expected survival curves in the stratified risk groups(low risk,P=0.61;high risk,P=0.77).CONCLUsION:Our data suggest that the proposed model is able to accurately predict survival in cirrhotic patients.

关键词：模型预测肝病末期患者临床生化应用

Glial plasticity after hexahydrobenzene exposure

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Neural Regeneration Research 2016年第3期11卷 404-405页

作者： Tania Campos-Ordonez oscar Gonzalez-Perez Laboratory of Neurobiology School of PsychologyUniversity of Colima Medical sciences PhD Program School of MedicineUniversity of Colima

The organic solvents are not only utilized in industrial processes,but also as drugs of *** fact,solvent consumption represents the fourth option for drug users just after alcohol,tobacco and *** humans,intentional in... 详细信息

关键词： intentional tobacco plasticity utilized volatile alcohol exposure abuse morphological microglia

synthetic Time series Generation Model for Analysis of Power system Operation and Expansion with High Renewable Energy Penetration

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journal of Modern Power systems and Clean Energy 2021年第4期9卷 849-858页

作者： Rodrigo Palma-Behnke jorge Vega-Herrera Felipe Valencia oscar Nunez-Mata Energy Center Department of Electrical EngineeringFaculty of Mathematical and Physical SciencesUniversity of ChileSantiagoChile department of Electrical Engineering University of AntofagastaAntofagastaChile school of Electrical Engineering University of Costa RicaSan PedroCosta Rica

The increasing integration of renewable energy sources into current power systems has posed the challenge of adequately representing the statistical properties associated with their variable power generation. In this paper, a novel procedure is proposed to select a proper synthetic time series generation model for renewable energy sources to analyze power system problems. The procedure takes advantage of the objective of the specific analysis to be performed and the statistical characteristics of the available time series. The aim is to determine the suitable model to be used for generating synthetic time series of renewable energy sources. A set of indicators is proposed to verify that the statistical properties of synthetic time series fit the statistical properties of the original data. The proposal can be integrated into systematic tools available for data analysis without compromising the representation of the statistical properties of the original time series. The procedure is tested using real data from the New Zealand power system in a mid-term analysis on integrating wind power plants into the power system. The results show that the proposed procedure reduces the error obtained in analyzing power systems compared with reference models.

关键词： Time series analysis renewable energy source solar energy stochastic process statistical analysis wind energy

Comparative Gas Exchange of Ulmus crassifolia (Cedar Elm, Ulmaceae) and Ungnadia speciosa (Mexican Buckey, sapindaceae) at Ambient and Elevated Levels of Light, CO<sub>2sub> and Temperature

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American journal of Plant sciences 2023年第6期14卷 691-709页

作者： Matthew B. Grunstra oscar W. Van Auken department of Integrative Biology University of Texas at San Antonio San Antonio TX USA

Ulmus crassifolia Nutt. (Cedar elm, Ulmaceae) is a tree found in central and east Texas, northern Mexico, east to Florida, and north to southern Missouri and Oklahoma. Ungnadia speciosa Endl. (Mexican-buckeye, sapindaceae) is a shrub or small tree found in woodlands and savannas of central and western Texas, southern New Mexico and northern Mexico. In central Texas, both species are found in Juniperus ashei/Quercus virginiana woodlands or savannas or also at low density in inter-canopy grassland gaps or patches. Environmental conditions in this area are stressful because of shallow soils, high summer temperatures, and inconsistent low rainfall. Currently, both species have a low density in these areas, and Ulmus crassifolia is usually a tree, while Ungnadia speciosa is a woody understory shrub. This study suggests U. crassifolia and U. speciosa are tolerant or intermediate species, with juveniles starting in shade. Maximum photosynthetic rate (Asub>maxsub>), dark respiration (Rsub>dsub>), intercellular COsub>2sub>, light saturation (Lsub>spsub>) and water use efficiency significantly increased when light levels and COsub>2sub> concentrations were elevated for both species, but not when temperatures were elevated. stomatal conductance decreased when the COsub>2sub> concentration doubled, but there were few effects from elevated temperature. These findings suggest that U. speciosa and U. crassifolia should be more common and imply that they will have a higher density in a future high COsub>2sub> environment.

关键词： Light Response Gas Exchange Photosynthesis Respiration Water Use Efficiency

An Architecture for software Engineering Gamification

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Tsinghua science and Technology 2020年第6期25卷 776-797页

作者： oscar Pedreira Felix Garcia Mario Piattini Alejandro Cortinas Ana Cerdeira-Pena the Universidade da Coruna Centro de Investigacion CITICLaboratorio de Bases de DatosFacultade de InformaticaElvinaA Coruna15071Spain the Universidad de Castilla-La Mancha Grupo AlarcosEscuela Superior de InformaticaPaseo de la Universidad4Ciudad Real13071Spain.

Gamification has been applied in software engineering to improve quality and results by increasing people’s motivation and engagement.A systematic mapping has identified research gaps in the field,one of them being the difficulty of creating an integrated gamified environment comprising all the tools of an organization,since most existing gamified tools are custom developments or *** this paper,we propose a gamification software architecture that allows us to transform the work environment of a software organization into an integrated gamified environment,i.e.,the organization can maintain its tools,and the rewards obtained by the users for their actions in different tools will mount *** developed a gamification engine based on our proposal,and we carried out a case study in which we applied it in a real software development *** case study shows that the gamification engine has allowed the company to create a gamified workplace by integrating custom-developed tools and off-the-shelf tools such as Redmine,TestLink,or JUnit,with the gamification *** main advantages can be highlighted:(i)our solution allows the organization to maintain its current tools,and(ii)the rewards for actions in any tool accumulate in a centralized gamified environment.

关键词： gamification software engineering gamification architecture gamification engine