检索结果-南通市图书馆

Journal of Wuhan university of Technology(Materials science) 2006年第4期21卷 141-145页

作者：魏小胜 department of Civil engineering Huazhong University of Science and Technology Wuhan 430074 China

The influence of calcium sulfate state and fineness of cement on hydration of Portland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early period. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the Portland cement decreases the minimum resistivhy due to a higher ionic concentration and increases the 2. hour resistivity due to a reduction in macroscopic pore size. The setting time, compressive strength, pore structure of pastes made from different cements were carried out to compare the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical properties are strongly affected by the initial porosity, the presence of hemihydrate or gypsum, and the fineness of cement.

关键词： false setting electrical resistivity fineness hydration

Characteristics of shape memory and superelasticity for TiNi thin films

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2000年第3期10卷 375-377页

作者： HE Zhi rong(贺志荣) 1, s.Miyazaki 2.1. department of mechanical {2., shaanxi Institute of Technology, Hanzhong 72.003, P.R.China 2. university of Tsukuba, Japan shaanxi Inst Technol Dept Mech Engn Hanzhong 723003 Peoples R China Univ Tsukuba Tsukuba Ibaraki 305 Japan

TiNi shape memory alloy thin films were deposited by using a RF magnetron sputtering apparatus. The transformation and shape memory characteristics of the thin films have been investigated by using DsC and tensile tes... 详细信息

关键词： TiNi alloy shape memory effect superelasticity thin film

Influence of modulation ratio on structure and properties of nanoscale ZrB_2.ZrAlN multilayered coatings

在线全文

学校读者我要写书评

暂无评论

science China(Technological sciences) 2010年第3期53卷 772-775页

作者： LI DeJun 1,KANG YuanBin 1,DONG Lei 1,DENG XiangYun 1,LIU Hao 2.&sUN XueLiang 2.1College of Physics and Electronic Information science,Tianjin Normal university,Tianjin 300387,China 2.department of {2.&Materials engineering,university of Western Ontario,london ON,Canada 1. College of Physics and Electronic Information science Tianjin Normal University Tianjin 300387 China2. Department of Mechanical & Materials Engineering University of Western Ontario London ON Canada

ZrB2.ZrAlN multilayered coatings with various modulation ratios(t ZrB2.t ZrAlN)and constant modulation periods were prepared by magnetron sputtering system at room ***,XRD,surface profiler and nano-indenter were employed to investigate the influences of tZ rB 2.tZrAlNon the microstructure and mechanical properties of the *** interfaces and nanoscale multilayered modulation were confirmed by *** multilayer with modulation period of 40 nm and ratio of 3:1 displayed the highest hardness(36.4 GPa)and critical fracture load(76.477 mN)with lower *** polycrystalline structure and multilayered modulate structure were directly responsible for the enhanced mechanical properties.

关键词： ZrB2.ZrAlN multilayered coating magnetron sputtering modulation ratio nanoscale

simulations on Various Lubrication Boundaries between Diamond-like Carbon Films

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials science) 2011年第4期26卷 658-660页

作者：兰惠清 school of mechanical Electronic and Control Engineering Beijing Jiaotong University

Molecular dynamics （MD） simulations were used to study a sliding friction process between DLC films on various boundary conditions. The experimental results revealed that, in the absence of a lubricant, a transfer film between the DLC films was formed. In contrast, when the oil or water lubricants were added to lubricate between the DLC films, a boundary lubrication layer was found. The friction forces on the water and oil lubrication were almost the same, but the friction force in the absence of a lubricant was larger than those on the water and oil lubrication. The conclusions were in good agreement with the experiments.

关键词： lubrication carbon molecular dynamics

Modeling and Assessment of Buoyancy-Driven stratified Airflow in High-space Industrial Hall

在线全文

学校读者我要写书评

暂无评论

湖南大学学报（自然科学版） 2009年第S1期36卷 19-22页

作者： WANG Han-qing1,2.CHEN Ke1,HU Jian-jun1,3,KOU Guang-xiao2.WANG Zhi-yong2.1.school of Energy science and engineering,Central south university,Changsha,Hunan 410083,China {2. of Civil engineering,Hunan university of Technology,Zhuzhou,Hunan 412.08,China 3.school of mechanical engineering,Purdue university,West Lafayette,UsA) school of Energy science and engineering Central South University Changsha 410083 China department of Civil engineering Hunan University of Technology Zhuzhou 412008 China school of mechanical engineering Purdue University West Lafayette United States

In industrial environment,heat sources often are contaminant sources and health threatening contaminants are mainly passive,so a detailed understanding of airflow mode can assist in work environment hygiene measurement and *** paper presented a numerical investigation of stratified airflow scenario in a high-space industrial hall with validated commercial code and experimentally acquired boundary *** upon an actually undergoing engineering project,this study investigated the performance of the buoyancy-driven displacement ventilation in a large welding hall with big components *** results have demonstrated that stratified airflow sustained by thermal buoyancy provides zoning effect in terms of clean and polluted regions except minor stagnant eddy *** competition between negative buoyant jets from displacement radial diffusers and positive buoyant plume from bulk object constitutes the complex transport characteristics under and above stratification ***,downdraft and turbulent eddy motion complicate the upper mixing zone,but the exhaust outlet plays a less important role in the whole field *** the corresponding suggestions concerning computational stability and convergence,further improvements in modelling and measurements were given.

关键词： modelling buoyancy-driven large enclosure industrial ventilation

Fuzzy controllers based on some fuzzy implication operators and their response functions

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2004年第1期14卷 16-21页

作者： LI Hongxing 1*, YOU Fei 1 and PENG Jiayin 2.1. department of Mathematics, Beijing Normal university, Beijing 100875, China 2. department of Mathematics, Neijiang Teacher's College, Neijiang 641112. China) Beijing Normal Univ Dept Math Beijing 100875 Peoples R China

The fuzzy controllers constructed by 2. fuzzy implication operators based on CRI algorithm and their response functions are discussed. The conclusions show that the fuzzy controllers constructed by 9 fuzzy implication operators are universal approximators to continuous functions and can be used in practical fuzzy control systems. And these 9 fuzzy implication operators except for Einstein operator intersection are all the adjoint pairs of some fuzzy implication operators. Besides, there are 3 other fuzzy controllers formed by fuzzy implication operators being regarded approximately as fitted functions.

关键词： fuzzy implication operators CRI algorithm fuzzy controllers response functions universal approximators

CRITERION　OF　sTOCHAsTIC　LAYER　NEAR　A　PLANAR　HOMOCLINIC　ORBIT　OF　NONLINEAR　DYNAMICAL　sYsTEM

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1995年第2期7卷 35-50页

作者： Albert C. J. Luo(department of mechanical & Industrial {2. university of Manitoba. Winnipeg, Manitoba, R3T 2.2.Canada) Univ of Manitoba Winnipeg Canada

A new analytic method is developed for nonlinear dynamical system, to investigate the mathematical structure and physical characteristics of the stochastic layer near a homoclinic or heteroclinic orbit. This method is based on the subharmonic resonant condition and an energy increment along the separatrix of the system. The critical conditions for the disappearance of stochastic layer are presented, which are associated with all control parameters of the system including initial conditions, excitation frequencies excitatiom amplitudes ***, using this method, we analyze two simple nonlinear dynamical systems, namely,Duffing-Holmes's equation and a forced planar pendulum. As their stochastic layers begin to disappear, their critical amplitudes are also obtained for the given excitation frequency and other chosen parameters. By means of these conditions, we carry out numerical simulations for the two simple models. Their stochastic layer will be shown using Poincare mapping section. Our theoretical results are subeequently shown to be in a good agreement with numerical simulations.

关键词： nonlinear dynamical system stochastic layer numerical simulation

Congruences on ideal nil-extension of completely regular semigroups

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 1998年第5期43卷 379-381页

作者： REN Xueming 1, 2.GUO Yuqi 2.and CEN Jiaping (shum Kar-ping) 31. department of Mathematics, Xi’an university of Architecture & Technology, Xi’an 710055, China 2. department of Mathematics, Yunnan university, Kunming 650091, China 3. department of department of Mathematics Xi’an University of Architecture & Technology Xi’an China department of Mathematics Yunnan University Kunming China department of Mathematics Chinese University of Hong Kong Hong Kong

Let s be an ideal nil-extension of a completely regular semigroup K by a nil semigroup Q with zero. A concept of admissible congruence pairs (δ,ω) of s is introduced, where δ and ω are a congruence on Q and a congruence on K respectively. It is proved that every congruence on s can be uniquely respresented by an admissible congruence pair (δ,ω) of s. suppose that ρ K denotes the Rees congruence induced by the ideal K of s. Then it is shown that for any congruence σ on s,a mapping Γ:σ|→(σ Q,σ K) is an order-preserving bijection from the set of all congruences on s onto the set of all admissible congruence pairs of s,where σ K is the restriction of σ to K and σ Q=(σ∨ρ K)/ρ K. Moreover,the lattice of congruences of s is also discussed. As a special case,every congruence on completely Archimedean semigroups s is described by an admissible quarterple of s. The following question is asked: Is the lattice of congruences of the completely Archimedean semigroup a semimodular lattice?

关键词： completely regular semigroups ideal nil-extension congruences.

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

在线全文

学校读者我要写书评

暂无评论

science China Chemistry 2006年第4期49卷 296-307页

作者： LI Ming1, ZHENG Wenxu2.& TIAN Anmin2.1. department of Chemistry, southwest-China Normal university, Chongqing 400715, China 2. department of Chemistry, sichuan university, Chengdu 610064, China 1. department of Chemistry Southwest-China Normal University Chongqing 400715 China 2. department of Chemistry Sichuan University Chengdu 610064 China

The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

关键词： keto oxime ether, oxazaborolidine, enantioselective reduction, DFT.

Improvement of the classification accuracy in discriminating diabetic retinopathy by multifocal electroretinogram analysis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2007年第8期17卷 913-918页

作者： Xu Jin~1 Hu Guangshu~(1**) Huang Houbin~2.(1.department of Biomedical engineering,Tsinghua {2.,Beijing 100084,China 2.department of Ophthalmology,General Hospital of Chinese PLA,Beijing 100853,China) [a]department of Biomedical engineering Tsinghua University Beijing China [b]department of Ophthalmology General Hospital of Chinese PLA Beijing China

The multifocal electroretinogram (mfERG) is a newly developed electrophysiological *** this paper,a classifi- cation method is proposed for early diagnosis of the diabetic retinopathy using mfERG *** records were obtained from eyes of healthy individuals and patients with diabetes at different *** each mfERG record,103 local responses were *** value of each point on all the mfERG local responses was looked as one potential feature to classify the experimental *** sub- sets were selected from the feature space by comparing the inter-intra *** on the selected feature subset,Fisher's linear classi- fiers were *** the final classification decision of the record was made by voting all the classifiers' *** the method to classify all experimental subjects,very low error rates were *** crucial properties of the diabetic retinopathy classification method are also discussed.

关键词： diabetic retinopathy multifocal electroretinogram feature selection linear classifier