检索结果-南通市图书馆

Advances in Manufacturing 2019年第2期7卷 238-247页

作者： dong-dong chen Yong-cheng Lin Xiao-Min chen School of Mechanical and Electrical Engineering Central South University Changsha 410083 People's Republic of China State Key Laboratory of High Performance Complex Manufacturing Changsha 410083 People's Republic of China College of Automotive and Mechanical Engineering Changsha University of Science and Technology Changsha 410114 People's Republic of China

In this study, a strategy based on the particle swarm optimization (PSO) algorithm is developed to control the microstructures of a Ni-based superalloy during hot forging. This strategy is composed of three parts, namely, material models, optimality criterions, and a PSO algo rithm. The material models are utilized to predict microstructure information, such as recrystallization volume fraction and average grain size. The optimality crite? non can be determined by the designed target microstructures and random errors. The developed strategy is resolved using the PSO algorithm, which is an intelligent optimal algorithm. This algorithm does not need a derivable objective function, which renders it suitable for dealing with the complex hot forging process of alloy components. The optimal processing parameters (deformation temperature and strain rate) are obtained by the developed strategy and validated by the hot forging experiments. Uniform and fine target microstructures can be obtained using the optimized processing parameters, which indicates that the developed strategy is effective for controlling the microstructural evolution during the hot forging of the studied superalloy.

关键词： Processing parameters Microstructure Particle swarm optimization (PSO) algorithm Superalloy

Modeling sintering behavior of metal fibers with different fiber angles

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

Rare Metals 2018年第10期37卷 886-893页

作者： dong-dong chen Zhou-Shun Zheng Jian-Zhong Wang Hui-Ping Tang School of Mathematics and Statistics Central South University State Key Laboratory of Porous Metal Materials Northwest Institute for Nonferrous Metal Research

The formation of sintering necks between two metal fibers was investigated using the oval-oval model with respect to the fiber angle range of 0°-90°. Surface diffusion was assumed to be the predominant mechanism in every section of the junction of two metal fibers in this model, which was addressed numerically using the level- set method. The growth rates of the sintering necks in the direction of the bisector of obtuse angle, the bisector of acute angle and the fiber axis were discussed in detail. It is found that the growth rate of the sintering necks decreases with fiber angle increasing in the direction of the fiber axis and the bisector of acute angle. However, an opposite variation in growth rate of sintering necks can be found in the direction of the bisector of obtuse angle. The numerical simulation results show that the growth rate of the sintering necks is significantly affected by the initial local geomet- rical structure which is determined by the fiber angle.

关键词： Metal fiber Surface diffusion Fiber angle Initial local geometrical structure Initial evolution speed

Genetic Prion Disease:Insight from the Features and Experience of China National Surveillance for Creutzfeldt-Jakob Disease

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2021年第11期37卷 1570-1582页

作者： Qi Shi Cao chen Kang Xiao Wei Zhou Li-Ping Gao dong-dong chen Yue-Zhang Wu Yuan Wang Chao Hu chen Gao Xiao-Ping dong State Key Laboratory for Infectious Disease Prevention and Control Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases(Zhejiang University)National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijing102206China Center for Global Public Health Chinese Center for Disease Control and PreventionBeijing102206China Center for Biosafety Mega-Science Chinese Academy of SciencesWuhan430064China China Academy of Chinese Medical Sciences Beijing100700China

Human genetic prion diseases(gPrDs)are directly associated with mutations and insertions in the PRNP(Prion Protein)*** collected and analyzed the data of 218 Chinese gPrD patients identified between Jan 2006 and June *** different subtypes were identified and gPrDs accounted for 10.9%of all diagnosed PrDs within the same *** subtypes of gPrDs showed a degree of geographic *** age at onset of Chinese gPrDs peaked in the 50–59 year ***–Sträussler–Scheinker syndrome(GSS)and fatal familial insomnia(FFI)cases usually displayed clinical symptoms earlier than genetic Creutzfeldt–Jakob disease(gCJD)patients with point mutations.A family history was more frequently recalled in P105L GSS and D178N FFI patients than T188K and E200K *** of the E196A gCJD patients reported a family *** gCJD cases with point mutations always developed clinical manifestations typical of sporadic CJD(sCJD).EEG examination was not sensitive for ***-associated abnormalities on MRI were found in high proportions of GSS and gCJD *** 14-3-3 positivity was frequently detected in gCJD *** CSF tau was found in more than half of FFI and T188K gCJD cases,and an even higher proportion of E196A and E200K gCJD patients.63.6%of P105L GSS cases showed a positive reaction in cerebrospinal fluid *** and FFI cases had longer durations than most subtypes of *** is one of the largest studies of gPrDs in East Asians,and the illness profile of Chinese gPrDs is clearly *** high proportions of T188K and E196A occur among Chinese gPrDs;these mutations are rarely reported in Caucasians and Japanese.

关键词： Genetic prion disease Mutation Surveillance Creutzfeldt-Jakob disease Gerstmann-Sträussler-Scheinker syndrome Fatal familial insomnia

A new phenanthraquinone from the roots of Peucedanum praeruptorum

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

Chinese Chemical Letters 2010年第7期21卷 816-817页

作者： Cun Zhang Li Li Yong Qing Xiao Wen Li Xiao Jie Yin Guo Fang Tian dong dong chen Yun Wang Institute of Chinese Materia Madica China Academy of Traditional Chinese MedicineBeijing 100700China

A new compound,9,10-dihydrophenanthrinic acid,9,10-dione-3,4-methylenedioxy-8-methoxy（1） was isolated from the roots of Peucedanum praeruptorum Dunn on the basis of spectral evidences.

关键词： Peucedanum praeruptorum 9 10-Phenanthraquinone 9 10-Dihydrophenanthrinic acid 9 10-Dione-3 4-methylenedioxy-8-methoxy

Low-temperature chlorination roasting technology for the simultaneous recovery of valuable metals from spent LiCoO_(2)cathode material

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 80-91页

作者： Junjie Shi Changle Hou Jingjing dong dong chen Jianzhong Li Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China

With the continuous increase in the disposal volume of spent lithium-ion batteries(LIBs),properly recycling spent LIBs has become essential for the advancement of the circular *** study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode *** activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free,model-fitting,and Z(α)function(αis conversion rate).Results indicated that the reaction was dominated by the first-order(F1)model when the conversion rate was less than or equal to 0.5 and shifted to the second-order(F2)model when the conversion rate exceeded *** conditions were determined by thoroughly investigating the effects of roasting temperature,roasting time,and the mass ratio of NH_(4)Cl to LiCoO_(2).Under the optimal conditions,namely 400℃,20 min,and NH_(4)Cl/LiCoO_(2)mass ratio of 3:1,the leaching efficiency of Li and Co reached 99.43% and 99.05%,*** of the roasted products revealed that valuable metals in LiCoO_(2)transformed into CoCl_(2) and ***,the reaction mechanism was elucidated,providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure *** technology can guide the development of LIB recycling processes with low energy consumption,low secondary pollution,high recovery efficiency,and high added value.

关键词： spent lithium-ion battery thermodynamics chlorination roasting kinetics circular economy

在线全文

学校读者我要写书评

暂无评论

日本感冒类汉方制剂处方标准和上市情况分析

中草药 2021年第22期52卷 7072-7077页

作者：董晨东王勇华润三九医药股份有限公司广东深圳518110

通过梳理日本汉方目录中的感冒药并查阅日本感冒药汉方制剂的文献、官方政策与标准等,分析日本感冒药汉方制剂的处方标准,并对其上市批准文号与生产厂家进行整理。日本感冒药汉方制剂相关标准收载的内容较为详细,制剂种类与生产厂家数... 详细信息

通过梳理日本汉方目录中的感冒药并查阅日本感冒药汉方制剂的文献、官方政策与标准等,分析日本感冒药汉方制剂的处方标准,并对其上市批准文号与生产厂家进行整理。日本感冒药汉方制剂相关标准收载的内容较为详细,制剂种类与生产厂家数量较多,其中颗粒剂最为成熟。建议加快建立我国古代经典名方关键信息,对治疗常见病的经典名方上市应用给予更多关注,并为经典名方剂型开发与改善提供有益借鉴。

关键词：汉方制剂感冒药品种分析处方标准上市情况古代经典名方

基于BIGRU的番茄病虫害问答系统问句分类研究

在线全文

学校读者我要写书评

暂无评论

农业机械学报 2018年第5期49卷 271-276页

作者：赵明董翠翠董乔雪陈瑛中国农业大学信息与电气工程学院北京100083

问句分类作为问答系统的关键模块,对系统检索效率具有决定性作用。为了对番茄病虫害智能问答系统用户问句进行高效分类,构建了基于word2vec和双向门控循环单元神经网络(Bi-directional gated recurrent unit,BIGRU)的番茄病虫害问句分... 详细信息

问句分类作为问答系统的关键模块,对系统检索效率具有决定性作用。为了对番茄病虫害智能问答系统用户问句进行高效分类,构建了基于word2vec和双向门控循环单元神经网络(Bi-directional gated recurrent unit,BIGRU)的番茄病虫害问句分类模型。针对问答系统对用户问句的语义信息有较高要求的特点,首先利用word2vec将句子中的词转换为具有语法、语义信息的词向量,利用训练得到的词向量和BIGRU神经网络进行问句分类模型的训练。实验选取了2 000个番茄病虫害相关的用户问句,主要分为番茄病害和番茄虫害两类。结果表明,采用BIGRU的番茄病虫害问句分类模型,其分类准确率、召回率和准确率与召回率的调和平均值F1分别高于卷积神经网络(CNN)、K最近邻等分类算法2~5个百分点。BIGRU模型结构简单,模型训练参数较少,模型训练速度快,符合问答系统对响应时间的要求。

关键词：番茄病虫害问答系统问句分类 BIGRU

卖空压力影响公司融资约束吗——基于中国A股上市公司的实证证据

在线全文

学校读者我要写书评

暂无评论

经济理论与经济管理 2017年第10期37卷 71-87页

作者：李栋栋陈涛琴复旦大学管理学院邮政编码200433

代理成本和信息不对称是导致公司出现融资约束的重要原因。本文以2010年3月正式推出的融资融券制度为外生冲击,以2005—2015年间沪深两市A股非金融类上市公司为研究样本,利用双重差分(difference-in-difference)模型实证检验了卖空压力... 详细信息

代理成本和信息不对称是导致公司出现融资约束的重要原因。本文以2010年3月正式推出的融资融券制度为外生冲击,以2005—2015年间沪深两市A股非金融类上市公司为研究样本,利用双重差分(difference-in-difference)模型实证检验了卖空压力对公司融资约束的影响。本文研究发现:(1)卖空压力能够提高公司银行贷款规模,降低贷款成本;(2)卖空压力能够降低公司的现金持有水平;(3)卖空压力能够降低公司的现金—现金流敏感性。综合来看,卖空压力能够缓解公司融资约束。进一步的,卖空压力对公司融资约束的缓解作用在民营企业中更加显著,并且卖空压力可能是通过降低公司代理成本和信息不对称程度进而缓解融资约束的。在各种稳健性检验后,本文研究结论保持不变。

关键词：卖空压力融资约束产权性质代理成本信息不对称程度

Discrete multi-step phase hologram for high frequency acoustic modulation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第1期33卷 488-495页

作者：周梦晴李照希李怡王业成张娟谌东东全熠杨银堂费春龙 School of Microelectronics Xidian UniversityXi'an 710071China

Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional(3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields.

关键词： discrete multi-step phase hologram econstruction quality 3D printing accuracy high-fidelity

Microstructural evolution during the progressive transformation-induced plasticity effect in a Fe-0.1C-5Mnmedium manganese steel

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 369-379页

作者： Mei Zhang Wenhao Li Yangfei chen Yang Jiang Xiaofei Guo Han dong School of Materials Science and Engineering Shanghai UniversityShanghai 200444China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China

The microstructural evolution of a cold-rolled and intercritical annealed medium-Mn steel(Fe-0.10C-5Mn)was investigated during uniaxial tensile ***-situ observations under scanning electron microscopy,transmission electron microscopy,and X-ray diffraction analysis were conducted to characterize the progressive transformation-induced plasticity process and associated fracture initiation *** findings were discussed with the local strain measurements via digital image *** results indicated that Lüders band formation in the steel was limited to 1.5%strain,which was mainly due to the early-stage martensitic phase transformation of a very small amount of the less stable large-sized retained austenite(RA),which led to localized stress concentrations and strain hardening and further retardation of *** small-sized RA exhibited high stability and progressively transformed into martensite and contributed to a stably extended Portevin-Le Chatelier *** volume fraction of RA gradually decreased from 26.8%to 8.2%prior to *** the late deformation stage,fracture initiation primarily occurred at the austenite/martensite and ferrite/martensite interfaces and the ferrite phase.

关键词： medium-Mn steel retained austenite progressive transformation-induced plasticity effect local strain fracture initiation