检索结果-南通市图书馆

Palaeoskapha sichuanensis gen. et sp. nov. (Menispermaceae) from the Eocene Relu Formation in western Sichuan, West China

在线全文

学校读者我要写书评

暂无评论

植物分类学报 2007年第4期45卷 576-582页

作者： Frederic M. B. jacques GUO Shuang-Xing Museum National d＇Histoire Naturelle D~partement Histoire de la Terre CP 38 UMR 5143 - USM 0203 8 rue Buffon 75231 Pads Cedex 05 France Nanjmg Institute of Geology and Palaeontology the Chinese Academy of Sciences Nanjing 210008 China Kunming lnstitute of Botany the Chinese Academy of Sciences Ktmming 650204 China

Palaeoskapha sichuanensis gen. et sp. nov. of Menispermaceae is described here for the first time based on a well preserved fossil fruit. The specimen was found in the Relu Formation of western Sichuan, West China. The specimen, straight, boat-shaped endocarp with large ventral condyle, clearly belongs to the tribe Tinosporeae. The wide aperture of the double condyle, combined with a whole shape not deeply invaginated, indicates a genus different from what was already known to science for this tribe. This fossil widens the distribution of the tribe during Eocene from North America and Europe to Asia, where it was formerly unknown.

关键词：防已科始新世四川群系新种植物化石果实

COURSE TIMETABLING AT A TUNISIAN UNIVERSITY:A CASE STUDY

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2008年第3期17卷 334-352页

作者： Abdelaziz DAMMAK Abdelkarim ELLOUMI Hichem KAMOUN jacques A.FERLAND Department of Applied Quantitative Methods GIAD Laboratory University of SfaxFSEGTunisia Department of Applied Quantitative Methods GlAD Laboratory University of SfaxFSEGTunisia Département d'Informatique et de Recherche Opérationnelle Universitéde Montréal QuébecCanada

This paper deals with the Course Timetabling Problem at an institution in a Tunisian University. We introduce a heuristic procedure to construct a feasible timetable for all lectures and tutorials taken by different groups of each sub-section of any section. We describe the timetabling problem using a list of all specific hard and soft constraints. We formulate the problem as a set of linear constraints using two sets of binary variables corresponding to lectures and tutorials, respectively. This heuristic is illustrated with real data for a sub-section of the Faculty of Economics and Management Sciences of Sfax in Tunisia, and the resulting timetables are compared with those generated manually. The results of another full section have confirmed the good quality of the proposed heuristic when compared with the hand made solution.

关键词： Educational timetabling integer programming implementations heuristic search

Numerical investigation of velocity ratio effect in combined wall and offset jet flows

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2018年第6期30卷 1105-1119页

作者： Nidhal Hnaien Salwa Marzouk Habib Ben Aissia jacques Jay Unité de Métrologie et des systèmes énergétiques Ecole National d'ingénieurs de Monastir Tunisie Centre de Thermique de Lyon (CETHIL-UMR CNRS 5008) INSA de Lyon France

In the present work, we propose to numerically study a combined turbulent wall and offset jet flow(this combination will be denoted WOJ). Several turbulence models were tested in this study: the standard k-w, SST k-w, standard k-ε, RNG, and realizable k-ε model. A parametric study was performed to determine the effect of offset ratio H and the velocity ratio r on the longitudinal and transverse positions of the merge point(MP), the combined point(CP), the upper vortex center(UVC) and the lower vortex center(LVC). Correlations that predict the position of these characteristic points of the WOJ flow as a function of H and r have been provided. Results show that any increase in the velocity ratio causes a displacement of the MP, CP, UVC and LVC further upstream along the longitudinal direction. Concerning the transverse positions, the increase of velocity ratio results in a deviation of the merge point(MP) and the lower vortex center(LVC) toward the strong jet(LWJ) whereas the transverse position of combined point(CP) and the upper vortex center(UVC) is almost independent of the velocity ratio.

关键词： Finite volume combined point merge point offset jet velocity ratio

Fractional order extremum seeking approach for maximum power point tracking of photovoltaic panels

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2015年第1期9卷 43-53页

作者： Ammar NECAIBIA Samir LADACI Abdelfatah CHAREF Jean jacques LOISEAU Research Unit in Renewable Energies in the Saharan Medium CDEREPST URER-MS Adrar 01000 Algeria Department ofElectrical Engineering University of Skikda Skikda 21000 Algeria Department of Electronics Electrotechnics and Automatics NationalPolytechnic School of Constantine Constantine 25000 Algeria SP-LabLaboratory Department of Electronics University of Constantine 1Constantine 25000 Algeria SP-Lab Laboratory Department of Electronics University of Con-stantine 1 Constantine 25000 Algeria Research Institute in Communications and Cybernetics CNRS UMR6597 1 rue de la No~ 44321 Nantes France

Due to the high interest in renewable energy and diversity of research regarding photovoltaic （PV） array, a great research effort is focusing nowadays on solar power generation and its performance improvement under various weather conditions. In this paper, an integrated framework was proposed, which achieved both maximum power point tracking （MPPT） and minimum ripple signals. The proposed control scheme was based on extremum- seeking （ES） combined with fractional order systems （FOS）. This auto-tuning strategy was developed to maximize the PV panel output power through the regulation of the voltage input to the DC/DC converter in order to lead the PV system steady-state to a stable oscillation behavior around the maximum power point （MPP）. It is shown that fractional order operators can improve the plant dynamics with respect to time response and disturbance rejection. The effectiveness of the proposed controller scheme is illustrated with simulations using measured solar radiation data.

关键词： extremum seeking (ES) fractional ordercontrol (FOC) fractional calculus photovoltaic (PV)

Chemical Indicator of Spinel During Partial Melting and Subsolidus Equilibration of Mantle Peridotite:Experimental Study and Application to Natural Rocks

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 1995年第4期69卷 420-435页

作者： jacques Kornprobst Daniel Vielzeuf Departement de Geologie et Mineralogie University Blaise Pascal63038 Clermont-Ferrand FranceDepartement de Geologie et Mineralogie University Blaise Pascal63038 Clermont-Ferrand France

Systematic experimental studies on partial melting and subsolidus equilibration of three reconstituted spinel-peridotites have been carried out at temperatures ranging from 1000 to 1380℃ and pressures of 1.0 and 1.5 GPa. The results shows (1) during partial melting, Mg# [=Mg/(Mg+Fe)]and Cr# [=Cr/(Cr-Al)]of spinel increase with an increase in degrees of melting) (2) during subsolidus equilibration, with increasing temperatures, Mg# of spinel increases but Cr# of spinel remains almost unchanged in dunite and increases slightly in Iherzolite and harzburgite. The negative and quasi-linear Mg# -Cr# correlation of spinel represents an isotherm of total non-equilibrium. The same results have been obtained by means of mathematical modelling. It is also proved by Mg# -Cr# correlation of spinel in natural peridotites. As a result of the spinel subsolidus equilibration, only variation of Cr# of spinel is limited, and then Cr# of spinel can be used to estimate the relative degree of melting undergone by host rocks. The bigger Cr# of spinel is, the higher the degree of melting will be. By contrast, during crystallization magma, Mg# and Cr# of spinel decrease with decreasing temperatures. Likewise, Cr# of spinel in basalts may be used to indicate the feature of Cr2O3/Al2O3 of magma, and the compositional zoning of spinel may be used to study the evolution of magma (cooling rate and contamination).

关键词： peridotite spinel partial melfing subsolidus equilibration experimental study and application

Planning urban megaprojects in the Gulf： The international consultancy firms in urban planning between global and contingent

在线全文

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2016年第2期5卷 254-264页

作者： Oula Aoun jacques Teller ARGENCO Universite Liege Liege 4000 Belgium

Driven by globalization and market openings, many architecture and engineering firms have become global. By focusing on the urban megaprojects in the Gulf, a particular culturat and political context, this paper argues that such firms have a major role in the rapid urban transformation of Gulf countries and act as transfer agents of an international knowledge in the urban planning domain. However, the transfer is adapted by several context-related char- acteristics, such as local governance, urban knowledge, and regulatory framework. This paper explores the procedural adaptation of these firms to the Gulf Cooperation Council （GCC） in terms of internal structure, methodology, adopted tools, and interaction with the context. The level of learning that results from this transfer is also investigated.

关键词： Architecture andensineering firms Construction market GCC Urban megaprojects

PAPR Distribution Analysis at the Output of Nonlinear PAPR Reducers

在线全文

学校读者我要写书评

暂无评论

Journal of Signal and Information Processing 2012年第4期3卷 465-468页

作者： Désiré Guel jacques Palicot SUPELEC/IETR Campus de Rennes Avenue de la Boulaie CS 47601 F-35576 Cesson-Sévigné cedex

Nonlinear PAPR reducers, such as clipping and companding techniques, are some simple methods used to reduce the Peak-to-Average Power Ratio (PAPR). In this paper, assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we investigate the PAPR distribution of an OFDM signal when it is passed through a nonlinear PAPR reducer. The obtained PAPR distribution depends on the nonlinear function which characterizes the PAPR reducer. Later in this paper, we apply the obtained PAPR distribution in the clipping case. The comparisons made between the proposed distribution and that obtained thanks to computer simulations show good agreement.

关键词： Orthogonal Frequency Division Multiplexing (OFDM) Peak-to-Average Power Ratio (PAPR) Distribution Nonlinear PAPR Reducers

Field investigation on friction factor in mountainous cobble-bed and boulder-bed rivers

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

International Journal of Sediment Research 2011年第2期26卷 210-221页

作者： Hossein AFZALIMEHR jacques GALLICHAND Ehsan BAGHERI Department of Water Engineering Isfahan University of Technology Departement des sols et de genie agroalimentaire Universite Laval Water Engineering Department Isfahan University of Technology

This paper presents results of the friction factor of cobble-bed and boulder-bed rivers based on 23 field measurements in three mountainous rivers in *** reveal that features of our measured velocity profiles in boulder-bed rivers in mountainous region do not present a specific shape but illustrate specific pattern in cobble-bed *** difference is attributed to scale effect of relative submergence. It is found that the relative submergence in cobble and boulders-bed rivers is the only key parameter that influences friction factor estimation and other parameters such as particle Froude number and Froude number have few impacts on flow resistance of cobble-bed and boulder-bed *** proposed relationship for estimation for the friction factor should be useful for large coarse-bed rivers.

关键词： Boulder-bed Cobble-bed Friction factor Mountainous river Relative submergence

Investigation of turbulence characteristics in channel with dense vegetation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2011年第3期26卷 269-280+282+281页

作者： Hossein AFZALIMEHR Razieh MOGHBEL jacques GALLICHAND Water Engineering Department Isfahan University of TechnologyIran 84156 Departement des sols et de genie agroalimentaire Universite LavalSt-FoyQcCanada

In this experimental study,the turbulent flow in a channel with vegetation by using sprouts of wheat on channel bed was *** different aspect ratios of channel were *** Acoustic Doppler Velocimetry was used to measure parameters of turbulent flow over submerged sprouts of wheat,such as velocity *** log law and the Reynolds shear stress distribution were applied. Results indicate that the position of the maximum turbulence intensity superposes on the inflection point situated over the top of submerged vegetation *** analysis shows that near the vegetation bed,the sweeps and ejections appear to be the most dominant phenomenon,while far from the vegetated bed,the outward is dominant *** also show that the aspect ratio plays an important role on the contribution of the different bursting events for Reynolds stress determination.

关键词： Bed vegetation Aspect ratio Reynolds stress Quadrant analysis