检索结果-南通市图书馆

International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 843-848页

作者： hai-tao li Bo-ping Zhang Wei-gang Yang Nan Ma School of Materials Science and Engineering He'nan University of Science and Technology Luoyang 471003 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

ZnO-modified (li, Na, K)NbO3 lead-free ceramics with a nominal composition of li0.06(Na0.535K0.48)0.94NbO3+0.7mol% ZnO (LNKN-ZT) was synthesized normally at 930-1000℃. The Zn ions incorporated into the A-site at a higher sintering temperaVare, which changed LNKN-Z7 to soft piezoelectric ceramics with the mechanical quality factor decreasing from 228 to 192. A phase transition from tetragonal to orthorhombic symmetry was identified by XRD analysis, and the corresponding calculation of lattice parameters was conducted at 970-980℃. Because of such transitional behavior and fine microstructure, the optimized values of piezoelectric coefficient, planar electromechanical coupling coefficient, and relative dielectric constant were obtained.

关键词： piezocemmics niobates zinc oxide modification phase transitions piezoelectricity sintering

Microstructure,crystalline phase and electrical properties of li_(0.06)(Na_(0.5)K_(0.5))_(0.94)Nb_(1-2x/5)Mg_xO_3 lead-free piezoelectric ceramics

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 340-346页

作者： hai-tao li Bo-ping Zhang Qian Zhang Peng-peng Shang Gao-lei Zhao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Henan University of Science and Technology Luoyang 471003 China

MgO-modified li0.06（Na0.5K0.5）0.94NbO3O3 （L6NKN） lead-free piezoelectric ceramics were synthesized by normal sintering at a rela- tively low temperature of 1000℃. The crystalline phase, microstructure, and electrical properties of the ceramics were investigated with a special emphasis on the influence of MgO content. The addition of MgO effectively improves the sintembility of the L6NKN ceramics. X-my diffr cfion analysis indicates that the morphotropic phase boundary （MPB） separating orthorhombic and tetragonal phases for the ceramics lies in the range of Mg doping content （x） from 0.3at% to 0.7at%. High electrical properties of the piezoelectric constant （d33=238 pC/N）, planar electromechanical coupling coefficient （kp=41.5%）, relative dielectric constant （εr=905）, and remanent polarization （Pr=38.3 μC/cm2） are obtained from the specimen with x=0.5at%, which suggests that the li0.06（Na0.5K0.5）0.94Nb（1-2x/5）MgxO3 （x=0.5at%） ceramic is a promising lead-free piezoelectric material.

关键词： lead-flee piezoelectric ceramics sinterability sintering morphotropic phase boundary

A New Flatness Pattern Recognition Model Based on Cerebellar Model Articulation Controllers Network

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2008年第5期15卷 32-36页

作者： HE hai-tao li Yan College of Information Science and Engineering Yanshan University Qinhuangdao 066004 Hebei China

In the traditional flatness pattern recognition neural network, the topologic configurations need to be rebuilt with a changing width of cold strip. Furthermore, the large learning assignment, slow convergence, and local minimum in the network are observed. Moreover, going by the structure of the traditional neural network, according to experience, the model is time-consuming and complex. Thus, a new approach of flatness pattern recognition is proposed based on the CMAC （cerebellar model articulation controllers） neural network. The difference in fuzzy distances between samples and the basic patterns is introduced as the input of the CMAC network. Simultaneously, the adequate learning rate is improved in the error correction algorithm of this neural network. The new approach with advantages, such as high learning speed, good generalization, and easy implementation, is efficient and intelligent. The simulation results show that the speed and accuracy of the flatness pattern recognition model are obviously im proved.

关键词： flatness pattern recognition CMAC neural network fuzzy distance

Seasonal Variation of δ^13C of Four Tree Species： A Biological Integrator of Environmental Variables

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2005年第12期47卷 1459-1469页

作者： hai-tao li Jun XIA Le XIANG tao liANG Qi-Jing liU Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China

Foliar δ^13C values, an indicator of long-term intercellular carbon dioxide concentration and, thus, of long-term water use efficiency （WUE） in plants, were measured for Pinus massoniana Lamb., P. elliottii Engelm., Cunninghamia laceolata （Lamb.） Hook., and Schima superba Gardn. et Champ. in a restored forest ecosystem in the Jiazhu River Basin. Seasonal variation and the relationship between the foliar δ^13C values of the four species and environmental factors （monthly total precipitation, monthly average air temperature, relative humidity, atmospheric pressure, and monthly total solar radiation and evaporation） were investigated. The monthly δ^13C values and WUE of the four species increased with increasing precipitation, air temperature, solar radiation, and evaporation, whereas δ^13C values of the four species decreased with increasing relative humidity and atmospheric pressure. Despite significant differences in δ^13C seasonal means for the four species, our results demonstrate a significant convergence in the responses of δ^13C values and WUE to seasonal variations in environmental factors among the species investigated and that the δ^13C signature for each species gives a strong indication of environmental variables.

关键词： δ^13C Cunninghamia laceolata Pinus elliottii Pinus massoniana Schima superba water use efficiency (WUE)

Variant Scaling Relationship for Mass-Density Across Tree-Dominated Communities

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2006年第3期48卷 268-277页

作者： hai-tao li Xing-Guo Han Jian-Guo Wu Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China Laboratory of Quantitative Vegetation Ecology Institute of Botany the Chinese Academy of Sciences Beijing 100093 China Faculty of Ecology Evolution and Environmental Science School of Life Sciences Arizona State University Tempe AZ 85287-4501 USA

The past few decades have seen a resurgence of Interest in biological allometry. Specifically, a number of recent studies has suggested a -4/3 Invariant scaling relationship between mass and density that Is universally valid for tree-dominated communities, regardless of their phyietic affiliation or habitat. In the present study, we test this scaling relationship using a comprehensive forest biomass database, Including 1 266 plots of six blomes and 17 forest types across China. The present study shows that the scaling exponent of the massdensity relationship varies across different tree-dominated communities and habitats. This great variability In the scaling exponent makes any generalization unwarranted. Although Inappropriate regression methods can lead to flawed estimation of the scaling exponent, inconsistency of theoretical framework and empirical patterns may have undermined the validity of previous work.

关键词： allometry mass-density scaling relationship trees.

Lack of Evidence for 3/4 Scaling of Metabolism in Terrestrial Plants

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2005年第10期47卷 1173-1183页

作者： hai-tao li Xing-Guo HAN Jian-Guo WU Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China Laboratory of Quantitative Vegetation Ecology Institute of Botany the Chinese Academy of Sciences Beijing 100093 China Faculty of Ecology Evolution and Environmental Science School of Life Sciences Arizona State University Tempe AZ 85287-4501 USA

Scaling, as the translation of information across spatial, temporal, and organizational scales, is essential to predictions and understanding in all sciences and has become a central issue in ecology. A large body of theoretical and empirical evidence concerning allometric scaling in terrestrial individual plants and plant communities has been constructed around the fractal volume-filling theory of West, Brown, and Enquist （the WBE model）. One of the most thought-provoking findings has been that the metabolic rates of plants, like those of animals, scale with their size as a 3/4 power law. The earliest, single most-important study cited in support of the application of the WBE model to terrestrial plants claims that whole-plant resource use in terrestrial plants scales as the 3/4 power of total mass, as predicted by the WBE model. However, in the present study we show that empirical data actually do not support such a claim. More recent studies cited as evidence for 3/4 scaling also suffer from several statistical and data-related problems. Using a forest biomass dataset including 1 266 plots of 17 main forest types across China, we explored the scaling exponents between tree productivity and tree mass and found no universal value across forest stands. We conclude that there is not sufficient evidence to support the existence of a single constant scaling exponent for the metabolism-biomass relationship for terrestrial plants.

关键词： metabolism 3/4 power scaling terrestrial plants water use.

Robust H_∞ Filter Design for Time-delay Systems with Saturation

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 Automation and computing 2013年第4期10卷 368-374页

作者： Xiao-Fang Hong Yu-Zhen Wang hai-tao li School of Control Science and Engineering Shandong University Department of Electrical and Automation Shandong Labor Vocational and Technical College

This paper investigates the H∞ filtering problem for a class of linear continuous-time systems with both time delay and saturation. Such systems have time delay in their state equations and saturation in their output equations, and their process and measurement noises have unknown statistical characteristics and bounded energies. Based on the Lyapunov-Krasovskii stability theorem and the linear matrix inequalities （LMIs） technique, a generalized dynamic filter architecture is proposed, and a filter design method is developed. The linear H∞ filter designed by the method can guarantee the H∞ performance. The parameters of the designed filter can be obtained by solving a kind of LMI. An illustrative example shows that the design method proposed in this paper is very effective.

关键词： H∞ filter saturation time delay nonlinear system linear matrix inequality.

Some recent theoretical progress in Higgs boson and top quark physics at hadron colliders

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第29期59卷 3709-3728页

作者： Chong-Sheng li hai-tao li Ding-Yu Shao School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Center for High Energy Physics Peking University

The test of the Standard Model and search for New Physics signal are main aim of LHC *** the increasing of the measurement accuracy at the LHC,it is a major task in future to exceed the current accuracy of the theoretical predictions for important processes,in particular ones involving Higgs boson and top *** this review we briefly summarize some recent theoretical progress in Higgs boson and top quark physics,especially the fixed-order and resummation predictions in QCD at both the Tevatron and the LHC.

关键词：希格斯玻色子物理信号顶夸克强子对撞机 LHC实验 Tevatron 测量精度理论预测

Transcatheter closure of ventricular septal defect in patients with aortic valve prolapse and mild aortic regurgitation:feasibility and preliminary outcome

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2015年第4期8卷 315-318页

作者： Guan-liang Chen hai-tao li hai-Rong li Zhi-Wei Zhang Zhujiang Hospital Affiliated to Southern Medical University Department of Pediatric Cardiology Guangdong Cardiovascular InstituteGuangdong Academy of Medical ScienceGuangdong General Hospital Department of Cardiology Hainan General Hospital

Objective:To evaluate the feasibility,safety and efficacy of transcathcter closure of ventricular septal defect(VSD)in patients with aortic valve prolapse(AVP)and mild aortic regurgitation(AR).Methods:Between January 2008 and July 2014,transcatheter closure of VSD was attempted in 65 ***:The total intermediate closure successful rate in all subjects was 96.9%.During the perioperative period,no death,major bleeding,pericardial tamponade,occluder dislodgement,residual shunt or hemolysis *** procedures had been forced to suspend due to significant aggregation of device related aortic regurgitation,three cases of transient complete left bundle branch block occurred but did not *** 1-year followup,no patients had residual shunts and ***,grade of residual AR were relieved in 61.9%(39/63)cases and degree of AVP were ameliorated in 36.5%(23/63)patients;Conclusions:Transcatheter closure VSD in selected patients with AVP and mild AR is technically feasible and highly *** term safety and efficacy needs to be assessed.

关键词： Transcatheter closure Ventricular septal defect Aortic valve prolapsed Aortic regurgitation

Synthesis and Characterization of a HydrophilicHydrophobic IPN Composed of Poly(vinyl alcohol)and Polystyrene

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 2005年第12期16卷 1597-1599页

作者： Yi Zhen TAN Man Cai XU hai tao li College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081

A hydrophilic/hydrophobic interpenetrating polymer network （IPN） of poly （vinyl alcohol） / polystyrene was prepared by conversion of the IPN of poly （vinyl acetate）/polystyrene. The hydrophilic/hydrophobic IPN w... 详细信息

关键词： Hydrophilic/hydrophobic interpenetrating polymer network poly(vinyl alcohol) polystyrene