检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

电动拖拉机双电源并联控制研究

农机化研究 2025年第1期47卷 234-238页

作者：初香港王宝超陈叶青岛农业大学机电工程学院山东青岛266109

电动拖拉机具有结构简单和节能减排等优点,但现有电动拖拉机作业时采用单一动力电池能源,存在续航时间短的问题。为了提高电动拖拉机长续航供电能力,提出了一种基于下垂控制的直流双电源并联均流联合供电方案,利用MatLab/Simulink搭建... 详细信息

电动拖拉机具有结构简单和节能减排等优点,但现有电动拖拉机作业时采用单一动力电池能源,存在续航时间短的问题。为了提高电动拖拉机长续航供电能力,提出了一种基于下垂控制的直流双电源并联均流联合供电方案,利用MatLab/Simulink搭建了系统模型。仿真试验表明:单电源可以实现升压稳压控制;基于下垂控制的双电源并联均流能够实现双电源的电流均流;当切换不同功率负载时,系统电压随功率增加按比例下调,验证了该方案的可行性。

关键词：电动拖拉机双电源并联下垂控制动态仿真

A review of flotation and selective separation of pyrrhotite:A perspective from crystal structures

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2022年第4期32卷 847-863页

作者： Xiaoqin Tang ye chen School of Chemistry&Chemical Engineering Guangxi UniversityNanning 530004China School of Resources Environment and MaterialsGuangxi UniversityNanning 530004China Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials Guangxi UniversityNanning 530004China

Pyrrhotite is an associated mineral that exists widely in sulfide ore. The presence of pyrrhotite will affect the recovery of platinum group minerals. Therefore, researchers have paid increasing attention to the flotation separation of pyrrhotite. Pyrrhotite superstructures owning different Fe/S ratios results in various crystal structures, corresponding to different physical, chemical and electronic properties, and consequently different flotation behavior. In the present paper, a comprehensive review is conducted to discuss the influence of crystal structures on the natural floatability, mineral-reagent interaction, surface oxidation and flotation electrochemistry of pyrrhotite. The selective flotation process of pyrrhotite from its associated minerals is also reviewed in this paper. It is hoped that this review can summarize the newly published research results combined with some representative results from the past, to provide a theoretical basis for the study of the flotation mechanism of pyrrhotite and provide a new direction for future research on pyrrhotite.

关键词： Pyrrhotite Flotation Crystal structures Surface properties

Electrochemical codeposition of typical α+β phases Mg-Li alloys from the molten LiCl-KCl-MgCl_2 system

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第2期29卷 198-203页

作者： ye Ke chen ye ZHANG Milin Key Laboratory of the Ministry of Education for Superlight Materials ＆ Surface Technology College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 150001 China

Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl（50 wt.%：50 wt.%） melts containing different concentrations of MgCl2 at 973 *** voltammograms show that the underpotential deposition of lithium on pre-deposited magnesium leads to the formation of liquid Mg-Li *** deposition potentials of Mg（II） and Li（I） ions gradually near each other with MgCl2 concentration ***-Li alloys with typical α ＋ β phases could be obtained by potentiostatic electrolysis from LiCl-KCl melts containing 5 wt.% MgCl2 at -2.25 V ***/AgCl（cathodic current density 1.70 A·cm-2） for 2.5 h.α phase, α ＋ β phases, and β phase Mg-Li alloys with different lithium contents were obtained by potentiostatic electrolysis from LiCl-KCl melts with the different concentrations of *** samples were characterized by X-ray diffraction and scanning electron microscopy.

关键词： physical chemistry Mg-Li alloys electrochemical codeposition molten salt electrolysis

Effect of content and spin state of iron on electronic properties and floatability of iron-bearing sphalerite:A DFT+U study

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2023年第12期33卷 1563-1571页

作者： Yao Feng Zhuofan Li Jianhua chen ye chen State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures School of Chemistry&Chemical EngineeringGuangxi UniversityNanning 530004China MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Guangxi UniversityNanning 530004China School of Resources Environment and MaterialsGuangxi Higher School Key Laboratory of Minerals EngineeringGuangxi UniversityNanning 530004China

Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is *** this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U(DFT+U)calculations combined with coordination chemistry *** band gap of ideal sphalerite is 3.723 eV,and thus electron transition is difficult to occur,resulting in poor *** results suggest the band gap of sphalerite decreases with increasing iron *** low iron content,the decreased band gap facilitates electron transition;at this case,Fe^(2+)in a high-spin state possesses oneπelectron pair,which can form a weakπ-backbonding with xanthate,causing increasing ***,for medium and high iron-bearing sphalerite,with the further decrease of band gap,Fe^(2+)is oxidized to Fe^(3+)due to electrochemical interaction,and henceπ-backbonding is eliminated,leading to lower floatability of iron-bearing sphalerite,which is consistent with the flotation experimental *** work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.

关键词： Sphalerite Iron-bearing sphalerite Iron content Spin state Density functional theory

The joint Laplace transforms for killed diffusion occupation times

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2024年第3期39卷 398-415页

作者： LI Ying-qiu chen ye School of Mathematics and Statistics Changsha University of Science and TechnologyChangsha 410114China College of Mathematics and Computational Science Hunan University of Arts and ScienceChangde 415000China

The approach of Li and Zhou(2014)is adopted to find the Laplace transform of occupation time over interval(0,a)and joint occupation times over semi-infinite intervals(-∞,a)and(b,∞)for a time-homogeneous diffusion pr... 详细信息

关键词： time-homogeneous diffusion process occupation time joint occupation time Laplace transform Brownian motion with drift

Data envelopment analysis procedure with two non-homogeneous DMU groups

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2018年第4期29卷 780-788页

作者： chen ye WU Liangpeng LU Bo College of Economics and Management Nanjing University of Aeronautics and Astronautics

The classic data envelopment analysis（DEA） model is used to evaluate decision-making units＇（DMUs） efficiency under the assumption that all DMUs are evaluated with the same criteria setting. Recently, new researches begin to focus on the efficiency analysis of non-homogeneous DMU arose by real practices such as the evaluation of departments in a university, where departments argue for the adoption of different criteria based on their disciplinary characteristics. A DEA procedure is proposed in this paper to address the efficiency analysis of two non-homogeneous DMU groups. Firstly, an analytical framework is established to compromise diversified input and output（IO） criteria from two nonhomogenous groups. Then, a criteria fusion operation is designed to obtain different DEA analysis strategies. Meanwhile, Friedman test is introduced to analyze the consistency of all efficiency results produced by different strategies. Next, ordered weighted averaging（OWA） operators are applied to integrate different information to reach final conclusions. Finally, a numerical example is used to illustrate the proposed method. The result indicates that the proposed method relaxes the restriction of the classical DEA model,and can provide more analytical flexibility to address different decision analysis scenarios arose from practical applications.

关键词： data envelopment analysis (DEA) non-homogeneousdecision-making unit (DMU) criteria fusion Friedman test ordered weighted averaging (OWA) operator

A peep into mitochondrial disorder： multifaceted from mitochondrial DNA mutations to nuclear gene modulation

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2015年第12期6卷 862-870页

作者： Chao chen ye chen Min-Xin Guan School of Medicine Institute of Genetics Zhejiang University Hangzhou 310058 China Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases Zhejiang University Hangzhou 310058 China

Mitochondrial genome is responsible for multiple human diseases in a maternal inherited pattern, yet phenotypes of patients in a same pedigree frequently vary largely. Genes involving in epigenetic modification, RNA processing, and other biological pathways, rather than ＂threshold effect＂ and environmental factors, provide more specific explanation to the aberrant phenotype. Thus, the double hit theory, mutations both in mito- chondrial DNA and modifying genes aggravating the symptom, throws new light on mitochondrial dysfunc- tion processes. In addition, mitochondrial retrograde signaling pathway that leads to reconfiguration of cell metabolism to adapt defects in mitochondria may as well play an active role. Here we review selected examples of modifier genes and mitochondrial retrograde signaling in mitochondrial disorders, which refine our understanding and will guide the rational design of clinical therapies.

关键词： mitochondrial disorder mitochondrial DNAmutation nuclear modifier gene mitochondrial retrogradesignaling

Regulation of intestinal stem cell fate specification

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2015年第6期58卷 570-578页

作者： QI Zhen chen ye-Guang State Key Laboratory of Biomembrane and Membrane Biotechnology Tsinghua-Peking Center for Life Sciences School of Life SciencesTsinghua University

The remarkable ability of rapid self-renewal makes the intestinal epithelium an ideal model for the study of adult stem cells. The intestinal epithelium is organized into villus and crypt, and a group of intestinal stem cells located at the base of crypt are responsible for this constant self-renewal throughout the life. Identification of the intestinal stem cell marker Lgr5, isolation and in vitro culture of Lgr5+ intestinal stem cells and the use of transgenic mouse models have significantly facilitated the studies of intestinal stem cell homeostasis and differentiation, therefore greatly expanding our knowledge of the regulatory mechanisms underlying the intestinal stem cell fate determination. In this review, we summarize the current understanding of how signals of Wnt, BMP, Notch and EGF in the stem cell niche modulate the intestinal stem cell fate.

关键词： intestinal stem cells Wnt BMP Notch EGF fate specification

Dynamic Modeling and Simulation of Multi-body Systems Using the Udwadia-Kalaba Theory

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2013年第5期26卷 839-850页

作者： ZHAO Han ZHEN Shengchao chen ye-Hwa School of Mechanical Engineering Hefei University of Technology School of Mechanical Engineering Georgia Institute of Technology

Laboratory experiments were conducted for falling U-chain,but explicit analytic form of the general equations of motion was not *** modeling methods were developed for fish robots,however they just focused on the whole fish’s locomotion which does little favor to understand the detailed swimming behavior of ***-Kalaba theory is used to model these two multi-body systems and obtain explicit analytic equations of *** falling U-chain,the mass matrix is ***-order constraints are used to get the constraint force and equations of motion and the numerical simulation is *** results show that the chain tip falls faster than the freely falling *** fish robot,two-joint Carangiform fish robot is focused ***-steady wing theory is used to approximately calculate fluid lift force acting on the caudal *** on the obtained explicit analytic equations of motion(the mass matrix is singular),propulsive characteristics of each part of the fish robot are *** these two cases of U chain and fish robot,how to use Udwadia-Kalaba equation to obtain the dynamical model is shown and the modeling methodology for multi-body systems is *** is also shown that Udwadia-Kalaba theory is applicable to systems whether or not their mass matrices are *** the whole process of applying Udwadia-Kalaba equation,Lagrangian multipliers and quasi-coordinates are not ***-Kalaba theory is creatively applied to dynamical modeling of falling U-chain and fish robot problems and explicit analytic equations of motion are obtained.

关键词： Udwadia-Kalaba equation multi-body systems falling U-chain fish robot