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DFIG sliding mode control fed by back-to-back converter with DC-link voltage control for variable wind turbine PWM speed

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Frontiers in Energy 2014年第3期8卷 345-354页

作者： Youcef BEKAKRA djilani ben attous Department of Electrical Engineering University of Biskra Biskra 07000 Algeria Department of Electrical Engineering University of El Oued El Oued 39000 Algeria

This paper proposes an indirect power control of doubly fed induction generator （DFIG） with the rotor connected to the electric grid through a back-to-back pulse width modulation （PWM） converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-（P1） controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.

关键词： doubly fed induction generator (DFIG) windturbine back-to-back pulse width modulation (PWM) DC-link voltage sliding mode control

Artificial bee colony optimization for economic dispatch with valve point effect

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Frontiers in Energy 2014年第4期8卷 449-458页

作者： Yacine LABBI djilani ben attous Belkacem MAHDAD Department of Electrical Engineering University of El-Oued El-Oued 39014 Algeria Department of Electrical Engineering University of Biskra Biskra 07000 Algeria

In recent years, various heuristic optimization methods have been proposed to solve economic dispatch （ED） problem in power systems. This paper presents the well-known power system ED problem solution consider- ing valve-point effect by a new optimization algorithm called artificial bee colony （ABC）. The proposed approach has been applied to various test systems with incremental fuel cost function, taking into account the valve-point effects. The results show that the proposed approach is efficient and robust when compared with other optimiza- tion algorithms reported in literature.

关键词： artificial bee colony (ABC) algorithm eco- nomic dispatch (ED) valve-point effect optimization

Five Years Beyond Sendai——Can We Get Beyond Frameworks?

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International Journal of Disaster Risk Science 2020年第2期11卷 239-249页

作者： ben Wisner Institute for Risk and Disaster Reduction University College LondonLondon WCIE 6BTUK

The Sendai Framework for Disaster Risk Reduction 2015–2030(SFDRR) and its implementation is evaluated after its first five years. A dozen questions that the author and a colleague used in their evaluation of the Hyogo Framework for Action 2005–2015(HFA) are repeated. Improvements are noted in relation to possible coherence and alignment with other components of the Post-2015 Agenda, especially as regards climate change and urban disasters as well as the higher visibility of civil society and women, and also regarding the specificity of targets and monitoring of governments’ successes. Nevertheless, the overall conclusion is that both the HFA and the SFDRR fail to deal with root causes of disaster. A new,radically proactive leadership role is suggested for the United Nations Office for Disaster Risk Reduction in partnership with civil society in identifying and warning all engaged in Post-2015 Agenda activities of possible creation of new risk by agenda implementation activities,especially for the poor and already-marginalized.

关键词： Civil society Climate change Disaster risk reduction Hyogo framework Sendai framework

Geochemistry, mineral paragenesis and geothermal conditions of oreforming fluids from the Ain El Bey Cu–Fe deposit: potential occurrence of native gold and precious metal traces (North African orogenic belt, Northern Tunisia)

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Acta Geochimica 2024年第2期43卷 366-384页

作者： Rania ben Aissa Wiem ben Aissa Said Tlig Lassaad ben Aissa Abdessalem ben Haj Amara Faculty of Science of Bizerte University of Carthage7021 ZarzounaBizerteTunisia Laboratoire de Recherche Ressources Materiaux et EcosystemesUniversity of Carthage7021 ZarzounaBizerteTunisia Department of Geology University Claude Bernard Lyon 169622 VilleurbanneFrance Faculty of Science of Tunis University of Tunis-El ManarRommana1068 TunisTunisia

The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petromineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope--Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores(tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 ℃ for phase Ⅲ, from 254 to 350 ℃ for phase Ⅳ, and from 200 to 300 ℃ for phases Ⅴ and Ⅵ. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature(< 200 ℃) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.

关键词： Ore-formingﬂuids Mineral geochemistry Mineral geothermometers Native silver-gold Ain El Bey Ore deposit North Tunisia

Zircon U-Pb dating and geochemical study of the Xianggou granite in the Ma'anqiao gold deposit and its relationship with gold mineralization

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Science China Earth Sciences 2010年第2期53卷 220-240页

作者： LEE ben State Key Laboratory of Continental Dynamics Department of GeologyNorthwest University

Single zircon LA-ICP-MS U-Pb dating and lithogeochemical studies have been performed on the Xianggou monzonitic granitic porphyry outcropped in the Ma’anqiao gold deposit.A weighted average U-Pb age of 242.0±0.8 Ma for Xianggou monzonitic porphyry has been *** corresponds with the conclusions of previous studies indicating a syn-orogenic age (242±21 Ma) of the Qinling Orogenic Belt,suggesting that the formation of the Xianggou granite should be associated with the collisional event of the North China Plate and the Yangtze Plate in the Indosinian *** Xianggou granite is characterized by the high silicon and alkali of high K calc-alkaline series *** is rich in Al (Al2O3=14.49%-15.61%) and Sr (457.10-630.82 ppm),poor in Y (<16 ppm) and HREE (Yb<0.45 ppm),and exhibits high ratios of Sr/Y (76.24-97.34) and (La/Yb)N (29.65-46.10),as well as strongly fractionated REE *** geochemical characteristics suggest the Xianggou granite can be classified as C-type adakitic *** initial Sr isotope ratios for the Xianggou granite vary from 0.70642 to 0.70668,εNd(t) values from -4.54 to -3.98,and TDM values from 1152 Ma to 1220 *** low εNd(t) and ISr and high TDM values,as well as Na2O/K2O ratios of the Xianggou granite are close to 1 (Na2O/K2O=0.95-1.10),indicating that it is not an I-type adakite formed by partial melting of the subducting oceanic crust,nor adakitic rock formed by melting of the underplated basaltic lower crust,but the product of partial melting of the nonunderplated basaltic thickened lower *** from the Xianggou pluton have a homogeneous Hf isotopic composition with negative εHf(t) values (between -9.7 and -5.9,with an average of -6.9),indicating that the rock-forming materials were mostly extracted from the ancient crust,not from the depleted *** Xianggou monzonitic granitic porphyry is rich in LILE and LREE and depleted in HSFE,HREE and Y;the composition of trace element and REE are similar to those

关键词： zircon U-Pb dating Xianggou monzonitic granitic porphyry Carlin type and Carlin-like type gold deposits petrologenic and metallogenic dynamic background

Spatial point-pattern analysis as a powerful tool in identifying pattern-process relationships in plant ecology: an updated review

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Ecological Processes 2021年第1期10卷 772-794页

作者： Mariem ben-Said Applied Biology and Pathology Laboratory Department of BiologyFaculty of SciencesAbdelmalek Essaadi UniversityTetouanMorocco

Background:Ecological processes such as seedling establishment,biotic interactions,and mortality can leave footprints on species spatial structure that can be detectable through spatial point-pattern analysis(SPPA).Being widely used in plant ecology,SPPA is increasingly carried out to describe biotic interactions and interpret patternprocess ***,some aspects are still subjected to a non-negligible debate such as required sample size(in terms of the number of points and plot area),the link between the low number of points and frequently observed random(or independent)patterns,and relating patterns to *** this paper,an overview of SPPA is given based on rich and updated literature providing guidance for ecologists(especially beginners)on summary statistics,uni-/bi-/multivariate analysis,unmarked/marked analysis,types of marks,*** ambiguities in SPPA are also ***:SPPA has a long history in plant ecology and is based on a large set of summary statistics aiming to describe species spatial *** mechanisms known to be responsible for species spatial patterns are actually investigated in different biomes and for different *** processes,plant environmental conditions,and human intervention are interrelated and are key drivers of plant spatial *** spite of being not recommended,small sample sizes are more common in *** some areas,periodic forest inventories and permanent plots are scarce although they are key tools for spatial data availability and plant dynamic ***:The spatial position of plants is an interesting source of information that helps to make hypotheses about processes responsible for plant spatial *** the continuous progress of SPPA,some ambiguities require further clarifications.

关键词： Spatial analysis Point-pattern Summary statistics Second-order characteristics Spatial structure Species interactions Competition Facilitation Positive association Negative association

Early Cretaceous Tectonostratigraphic Evolution of the Southern Tunisian Margin Based on Gravity,Seismic and Potential Field Data:New Insights into a Geodynamic Evolution in a Tethyan and Mesogean Rifting Context

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Journal of Earth Science 2023年第3期34卷 879-899页

作者： Mohamed ben Chelbi Faculty of Sciences of Tunis Laboratory of GeodynamicGeonumeric and Geomaterials(L3G)LR18ES37University of Tunis El ManarTunisTunisia

Many geophysical and geological data have been used to interpret the tectonic evolution of the south-eastern part of the Tunisian margin and to analyze the dominant structures in the *** Menzel Habib Plain(MHP)and surroundings,targeted by this study,exhibits thick siliciclastic and carbonate formations attributed to the Early Cretaceous *** of seismic and gravimetric data coupled with analysis of the syndepositional faults affecting these formations prove that the Tunisian margin is dominated,during this period,by N-S to NE-SW extensional *** geodynamic evolution of the MHP is mainly due to the irregular normal movement of the N-S faults,which represents the southernmost branch of the N-S Axis(NSA)and of the NW-SE faults,which constitutes the SE segment of the South Atlasic fault corridor(SAFC).In addition,the NE-SW and E-W oriented faults contributed to this *** extensive periods,this network of faults determines horst and grabens basin geometry or tilted blocks inducing formation of several distinct areas with different subsidence ***,the normal activity of the major faults promotes the vertical mobilization of the Triassic salt resulting in the individualization of several diapiric bodies,some of which pierced their sedimentary *** dynamics reflect echoes of the sinistral drifting of Africa with respect to Europe,integrated in a long Tethyan rifting cycle,and the beginning of opening of the Mesogean Sea,respectively.

关键词： Tunisian margin Early Cretaceous extensive tectonics Tethyan and Mesogean rifting geodynamics

Solid-state photoinduced luminescence switch and its advanced optical applications

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Science China Chemistry 2018年第4期61卷 377-378页

作者： ben Zhong Tang Department of Chemistry The Hong Kong University of Science & Technology

Spiropyran（SP）and its derivatives were one of the earliest and most extensive systems in organic photochromic ***,the distinct absorption changes will occur during the structural isomerization from SP to merocyanine... 详细信息

关键词：光开关固态应用衍生物光反应异构化

FINDING THE TOPOLOGY OF IMPLICITLY DEFINED TWO ALGEBRAIC PLANE CURVES

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Journal of Systems Science & Complexity 2012年第2期25卷 362-374页

作者： ben GAO Yufu CHEN School of Mathematical Sciences Graduate University of Chinese Academy of Sciences

An algorithm is given for computing in a very efficient way the topology of two real algebraic plane curves defined *** authors preform a symbolic pre-processing that allows us later to execute all numerical computati... 详细信息

关键词： Algebraic curves cylindrical algebraic decomposition generic position subresultantssequence topology.