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THE DATA ENVELOPMENT ANALYSIS MODEL WITH INTERSECTION FORM PRODUCTION POSSIBILITY SET

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Journal of Systems Science & Complexity 2010年第6期23卷 1086-1101页

作者： Quanling wei Hong yan Institute of Operations Research and Mathematical Economics Renmin University of China Beijing 100872 China. Department of Logistics The Hongkong Polytechnic University Hongkong China.

The data envelopment analysis （DEA） model is used to evaluate the relative economic efficiency of a given set of decision making units （DMUs）. In this paper, the DEA production possibility set is transferred from the conventional sum form into the intersection form which is represented by a linear inequality system. Although it is time consuming to obtain the intersection form of the production possibility set, it suggests a new angle to investigate the properties of DMUs and to extend the DEA research further beyond the efficiency measurement. Following the intersection form, the analytical formula of the efficiency indicator and projection is given. Various aspects of technical efficiency, returns to scale and evidence of congestion of the DMUs are studied. The relationship between the weak DEA efficiency and the weak Pareto solution is discussed. Finally, a procedure for DMU grouping is proposed to help the decision makers for better resource reallocation and strategy adjustment.

关键词： Data envelopment analysis intersection form production possibility set.

Graphene Quantum Wells and Superlattices Driven by Periodic Linear Potential

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Chinese Physics Letters 2013年第4期30卷 170-173页

作者： yan.wei-Xian College of Physics and Electronics Shanxi UniversityTaiyuan 030006

The transfer matrices for both nonsingular and singular cases are constructed to ensure efficient and accurate numerical computation on the electronic and transport properties of graphene quantum wells and superlattices driven by periodic linear *** intuitive interpretation is given for the evolution behavior of the current flowing through the multiple graphene quantum wells/barriers by analyzing the interrelationship among the transmission,bias voltage,incident velocity,and linear potential *** energy minibands and density of states of the graphene superlattices with different periods are also examined by using analytical and numerical methods,showing that the period of superlattices plays a crucial role in energy bands and density of states.

关键词： potential. bands quantum

Two New Lipschitz Type Spaces and Their Characterizations

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Acta Mathematica Sinica,English Series 2022年第9期38卷 1523-1536页

作者： Ming Quan wei Dun yan.yan School of Mathematics and Statistics Xinyang Normal UniversityXinyang 464000P.R.China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049P.R.China

In this paper,we first introduce the weak Lipschitz spaces WLip_(q,α),1 详细信息

In this paper,we first introduce the weak Lipschitz spaces WLip_(q,α),1

关键词： Weak Lipschitz space commutator fractional maximal operator weak central bounded mean oscillation space Hardy operator

Effect of vegetation on soil bacteria and their potential functions for ecological restoration in the Hulun Buir Sandy Land,China

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Journal of Arid Land 2020年第3期12卷 473-494页

作者： yan.Ru FENG wei yan.hi Research Station School of Soil and Water ConservationBeijing Forestry UniversityBeijing 100083China Engineering Research Center of Forestry Ecological Engineering of the Ministry of Education Beijing Forestry UniversityBeijing 100083China

To date,much of research on revegetation has focused on soil microorganisms due to their contributions in the formation of soil and soil remediation ***,little is known about the soil bacteria and their functions respond to the diverse vegetational types in the process of vegetation *** of dominated vegetation,i.e.,Artemisia halodendron Turcz Ex Bess,Caragana microphylla Lam.,Hedysarum fruticosum *** Pinus sylvestris *** bacterial community structures and their potential functions in the Hulun Buir Sandy Land,China were determined using high-throughput 16S rRNA gene sequencing and phylogenetic investigation of communities by reconstruction of unobserved states(PICRUSt)in *** the dominant phyla of soil bacterial community among different types of vegetation,including Proteobacteria,Actinobacteria,Acidobacteria,Bacteroidetes and Firmicutes,were similar,the relative abundance of these dominant groups significantly differed,indicating that different types of vegetation might result in variations in the composition of soil bacterial *** addition,functional genes of bacterial populations were similar among different types of vegetation,whereas its relative abundance was significantly *** carbon fixation genes showed a high relative abundance in ***,*** carbon decomposition genes in ***,suggesting the variations in carbon cycling potential of different types of *** of assimilatory nitrate reduction genes was the highest in ***,*** nitrate reduction and nitrate reductase genes in ***,indicating higher nitrogen gasification loss and lower nitrogen utilization gene functions in *** structures and functional genes of soil bacterial community showed marked sensitivities to different plant species,presenting the potentials for regulating soil carbon and nitrogen cycling.

关键词： bacterial taxonomic composition functional gene vegetational type soil carbon and nitrogen 16S rRNA

Influence of Charging Oil Condition on Torque Converter Cavitation Characteristics

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 236-249页

作者： Cheng Liu Meng Guo Qingdong yan.wei wei School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401122China Advanced Technology Research Institute Beijing Institute of TechnologyJinan 250307China

Cavitation inside a torque converter induces noise,vibration and even failure,and these effects have been disregarded in previous torque converter design ***,modern torque converter applications require attention to this issue because of its high-speed and high-capacity ***,this study investigated the cavitation effect on a torque converter using both numerical and experimental methods with an emphasis on the influence of the charging oil feed location and charge *** fluid dynamics(CFD)models were established to simulate the transient cavitation behaviour in the torque converter using different charging oil pressures and inlet arrangements and testing against a base case to validate the *** CFD results suggested that cavitating bubbles mainly takes place in the stator of the torque *** transient cavitation CFD model yielded good agreement with the experimental data,with an error of 7.6%in the capacity constant and 7.4%in the torque *** the experimental and numerical studies showed that cavitation induced severe capacity degradation,and that the charge pressure and charging oil configuration significantly affects both the overall hydrodynamic performance and the fluid behaviour inside the torque converter because of *** the charge pressure and charging the oil from the turbine-stator clearance were found to suppress cavitation development and reduce performance degradation,especially in terms of the capacity *** study revealed the fluid field mechanism behind the influence of charging oil conditions on torque converter cavitation behaviour,providing practical guidelines for suppressing cavitation in torque converter.

关键词： Torque converter Cavitation CFD Transient flow

Nano products in daily life:to know what we do not know

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National Science Review 2016年第4期3卷 414-415页

作者： Yongyi wei Bing yan School of Chemistry and Chemical Engineering Shandong University School of Environment Jinan University

Over the past decade,products based on nanotechnology and nanomaterials have created a fast-growing consumer market（http://***/）.Over 1827 consumer products have reached the supermarkets and millions of *** least about 39different nanomaterials were found in these products,such as those made from metals（Ag,Ti,Zn,Au）,metal oxides（TiO;,Fe;O;,ZnO）,carbonaceous（carbon,CNTs,fullerenes,graphene）

关键词： CNTs life Nano products in daily life Zn

EVALUATION OF THREE-DIMENSIONAL NUMERICAL MODEL FOR SALINE INTRUSION AND PURGING IN SEWAGE OUTFALLS

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Journal of Hydrodynamics 2007年第1期19卷 48-53页

作者： WU wei yan.Zhong-min College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

Saline intrusion into sewage outfalls will greatly decrease the efficiency of the structures. The numerical model for this flow has been limited to one- and two-dimensional ones. In this article, a three-dimensional numerical model for saline intrusion and purging in sewage outfalls was developed. The flow was modeled in three dimensions under turbulent conditions with the RNG k-ε turbulence model. The numerical results provided quantitative evidence of the fundamental flow mechanisms that took place during saline intrusion and purging. The comparisons of the results with that of two-dimensional model and that of experiments indicate that the three-dimensional numerical model developed in this article is more effective in predicting the internal flow in outfalls.

关键词： saline intrusion sea ouffalls numericalsimulation three-dimensional numerical model

我国产业链供应链安全发展的逻辑、障碍与路径

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中国流通经济 2025年第1期39卷 76-85页

作者：刘伟华袁超伦黄艳娇天津大学管理与经济学部天津市300072

党的二十届三中全会强调要提升产业链供应链韧性和健全安全制度,打造自主可控、安全可靠的产业链供应链。在此背景下,研究我国产业链供应链安全发展的逻辑、障碍与路径,可以为实现我国产业链供应链安全发展提供重要的理论基础。产业链... 详细信息

党的二十届三中全会强调要提升产业链供应链韧性和健全安全制度,打造自主可控、安全可靠的产业链供应链。在此背景下,研究我国产业链供应链安全发展的逻辑、障碍与路径,可以为实现我国产业链供应链安全发展提供重要的理论基础。产业链供应链安全发展的逻辑,是实现产业链供应链安全需要确保主体要素和结构要素的安全。通过对大宗原料、规模化制造、高新技术、生产性服务四大重点产业的八家典型企业的多案例研究,基于主体要素和结构要素的安全逻辑,识别我国重点产业的产业链供应链安全障碍。进而构建产业链供应链安全发展的路径,包括维护路径和阶跃路径两个维度。维护路径强调从主体要素和结构要素两个视角展开。阶跃路径强调以社会引领、技术驱动、制度辅助为核心要素。为实现维护路径和阶跃路径的有效实施,对于维护路径,需要启动我国重要产业链供应链的韧性战略设计和完善本土产业链供应链安全预警机制;对于阶跃路径,需要通过产业集群和搭建产业信息服务体系支持本土企业深度参与全球产业链供应链重构,通过改革科技创新体制加快突破产业链供应链的关键核心技术,通过构建全国统一大市场推动产业链供应链增加需求活力。

关键词：产业链供应链安全发展典型障碍维护路径阶跃路径

A pipelined Reed-Solomon decoder based on a modified step-by-step algorithm

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Frontiers of Information Technology & Electronic Engineering 2016年第9期17卷 954-961页

作者： Xing-ru PENG wei ZHANG yan.yan.LIU School of Electronic and Information Engineering Tianjin UniversityTianjin 300072China College of Electronic Information and Optical Engineering Nankai UniversityTianjin 300071China

We propose a pipelined Reed-Solomon(RS) decoder for an ultra-wideband system using a modified stepby-step algorithm. To reduce the complexity, the modified step-by-step algorithm merges two cases of the original algorithm. The pipelined structure allows the decoder to work at high rates with minimum delay. Consequently, for RS(23,17) codes, the proposed architecture requires 42.5% and 24.4% less area compared with a modified Euclidean architecture and a pipelined degree-computationless modified Euclidean architecture, respectively. The area of the proposed decoder is 11.3% less than that of the previous step-by-step decoder with a lower critical path delay.

关键词： Reed-Solomon codes Step-by-step algorithm Ultra-wideband Pipelined structure