检索结果-南通市图书馆

RESIDUAL AUSTENITE AND STRAIN-INDUCED MARTENSITE IN LASER HARDENING LAYER ON GRAY IRON

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1990年第3期3卷 218-221页

作者： LI Chenglao SHEN Lian xi’an jiaotong university,xi’an,china LI Chenglao Lecturer Dept.of {2. {3.,xi’an jiaotong university,xi’an 710049,china

The distribution of residual austenite in the laser hardening laver on the gray cast iron and the change in the amount of residual austenite during sliding wearing have been investigated by X-ray *** thin foils of the hardening layer worn down have been observed by electron *** was revealed that two types of martensite are strain-induced by slid- ing wearing under load of 1.72.MPa on the hardening layer of residual *** strain induced martensite is profitable to improve the sliding wearing resistance.

关键词： laser surface modification gray cast iron residual austenite martensite wear resistance

Influence of Molecular Weight of PEO on Performance of Quasi-solid-state Dye-sensitized Solar Cells

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) 2010年第2期25卷 218-222页

作者：沈小林 school of materials Science & {2. Xi’an Jiaotong University

Quasi-solid-state dye-sensitized solar cells （DSCs） were prepared using gel electrolyte gelated by poly（ethylene-oxide）（PEO） with different molecular weight. With the increase in PEO molecular weight, the short circuit current densities （Jsc） increase significantly, which is related to the increase in I - diffusion due to the increase in free volume of gel electrolyte. However, only a slight increase in open voltage （Voc） is observed, which is explained by the decrease in dark current arising from the reduction of triiodide （I3.-） by conduction band electrons.

关键词： dye-sensitized solar cell poly(ethylene oxide) gel electrolyte molecular weight

Decarboxylative cyanation and thiocyanation via catalytic electron donor-acceptor complex with copper catalysis

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2024年第9期67卷 3019-3028页

作者： Hongping Zhao xiaoxiang xi Tianbao Wu Zimin Chen Minyan Wang Weiming Yuan Key Laboratory of material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Bioinorganic Chemistry and Materia MedicaSchool of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210093China Shenzhen Huazhong university of Science and Technology Research Institute Shenzhen 518000China

A new catalytic decarboxylative cyanation and thiocyanation via a synergistic Na I/Cu catalysis is *** photoexcited electron donor-acceptor complex by assembly of Na I,R3.,and N-acyloxy-phthalimide ester(NHPI ester)triggers the generation of alkyl radical species,which then engages in Cu-catalyzed radical coupling *** to success of this dual catalytic transformation is the reliable charge transfer between I·and Cu(I).This dual catalytic platform can eliminate the use of expensive iridium-based photocatalyst or synthetically elaborate organic dyes.A series of primary,secondary,and tertiary alkyl nitriles and thiocyanates are easily ***,an asymmetric decarboxylative cyanation by applying a chiral Cu catalyst is also developed to afford chiral nitriles in high *** mechanistic details and the origin of the high enantioselectivity are further investigated by the mechanistic experiments and the density functional theory calculations.

关键词： electron donor-acceptor catalysis copper catalysis cyanation thiocyanation asymmetric synthesis

A new adaptive fast motion estimation algorithm based on local motion similarity degree (LMSD)

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:materials International 2005年第12期15卷 1126-1134页

作者： LIU Long,HAN Chongzhao and BAI Yan school of Electronics & Information engineering,xi’an {2. {3.,xi’an 710049,china school of Electronics & Information engineering Xi''an Jiaotong University Xi''an 710049 China

In the motion vector field adaptive search technique (MVFAST) and the predictive motion vector field adaptive search technique (PMVFAST),the size of the largest motion vector from the three adjacent blocks (left,top,top-right) is compared with the threshold to select different search *** a suitable search center and search pattern will not be selected in the adaptive search technique when the adjacent motion vectors are not coherent in local *** paper presents an efficient adaptive search *** motion vector variation degree (MVVD) is considered a reasonable factor for adaptive search *** the relationship between local motion similarity degree (LMSD) and the variation degree of motion vector (MVVD),the motion vectors are classified as three categories according to corresponding LMSD; then different proposed search schemes are adopted for motion *** experimental results show that the proposed algorithm has a significant computational speedup compared with MVFAST and PMVFAST algorithms,and offers a similar,even better performance.

关键词： motion estimation motion vector video coding local motion

Optimal user scheduling and power control in multi-user cognitive broadcast systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第6期55卷 1402-1414页

作者： WANG QunHuan 1,2.3.WANG HuiMing 1,2.3.& YIN QinYe 1,3.1 school of Electronic and Information {3.,xi'an {2. university,xi'an 710049,china 2.State Key Lab for Integrated Services Networks,xidian university,xi'an 710071,china 3.Ministry of Education Key Lab for Intelligent Networks and Network Security,xi'an {2. university,xi'an 710071,china. 1. school of Electronic and Information engineering Xi’an Jiaotong University Xi’an 710049 China2. State Key Lab for Integrated Services Networks Xidian University Xi’an 710071 China3. Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an Jiaotong University Xi’an 710071 China

Cognitive radio systems should not only have the ability to sense and exploit "frequency spectrum holes",but also the ability to sense and utilize "spatial spectrum holes".In this paper,we consider the issue of maximizing the throughput of the cognitive systems by fully utilizing "spatial spectrum holes" brought in by multiple cognitive users,in the scenario where a pair of licensed users and a cognitive broadcast system share multiple spectrum *** exploiting the channel reciprocity under the premise that the licensed system adopts the time-division-duplexing (TDD) mode,we propose a more practical cognitive access scheme that can sense the interference at the licensed user caused by the cognitive transmitter,based on the existing feedback signals from the licensed user to the licensed base *** both interferences from the licensed base station to the cognitive receiver and from the cognitive transmitter to the licensed user into consideration,we investigate the optimal user scheduling and power allocation scheme that can maximize the ergodic sum rate of the cognitive *** show that scheduling the user whose channel gain to interference and noise ratio (CGINR) is the largest for each frequency band is *** also derive the dynamic power allocation scheme meeting the three practical constraints,i.e.,the transmitter's average transmission power constraint,the power amplifier's instantaneous transmission power constraint,and the interference power constraint at the licensed *** result shows that in different coherent time intervals and different frequency bands,the power allocation has a multi-level waterfilling *** analysis shows that the strategy scheduling user with the largest CGINR introduces significant performance improvement compared with the traditional strategy scheduling user with the largest channel gain to noise ratio (CGNR).We also illustrate the impact of power constraints and the number of users on system p

关键词： cognitive radio distributed spatial spectrum holes opportunistic scheduling power allocation

Binary particle swarm optimization with multiple evolutionary strategies

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第11期55卷 2485-2494页

作者： ZHAO Jing1,HAN ChongZhao1 & WEI Bin2.1Ministry of Education Key Lab For Intelligent Networks and Network Security,State Key Laboratory for Manufacturing Systems engineering,Institute of Integrated Automation,school of Electronics and Information engineering,xi'an jiaotong university,xi'an 710049,china 2.nstitute of System engineering,school of Electronics and Information engineering,xi'an jiaotong university,xi'an 710049,china 1. Ministry of Education Key Lab For Intelligent Networks and Network Security State Key Laboratory for Manufacturing Systems Engineering Institute of Integrated Automation School of Electronics and Information Engineering Xi’an Jiaotong University Xi’an 710049 China2. Institute of System Engineering School of Electronics and Information Engineering Xi’an Jiaotong University Xi’an 710049 China

This paper introduces a novel variation of binary particle swarm optimization(BPSO) algorithm and a further extension to improve its ***,mimicking the behaviors of some creatures group,multiple evolutionary strategies BPSO(MBPSO) is introduced which takes different evolutionary strategies for various particles according to their ***,on the basis of MBPSO,a new strategy is discussed to improve the performance of the MBPSO(M2.PSO) which adopts the concept of the mutation operator aiming to overcome the premature convergence and slow convergent speed during the later stages of the *** proposed two algorithms are tested on seven benchmark functions and their results are compared with those obtained by other *** results show that our methods outperform the other algorithms.

关键词： binary particle swarm optimizer evolutionary strategies swarm intelligence

A quantum-confinement model for surrounding-gate MOSFETS from subthreshold to strong-inversion regions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第10期55卷 2399-2408页

作者： LIU LinLin & LI ZunChao school of Electronics and information engineering,xi’an {2. {3.,xi’an 710049,china 1. school of Electronics and information engineering Xi’an Jiaotong University Xi’an 710049 China

A new analytical model is developed for quantum-confinement effects of short channel surroundinggate *** eigenenergies and wavefunctions are obtained by solving Schrdinger’s equation with an accurate potential energy *** potential energy distribution is derived from the solution of Poisson’s equation,which contains both depletion charge and free *** eigenenergies obtained from our model are compared with other two quantum-confinement models,which use flat-well approximation and parabola-well approximation as the potential energy distributions,*** we point out the relationship between the eigenenergies and the potential energy distribution for the first *** on this model,the electron density with quantum confinement effects are derived,and threshold voltage is defined based on average electron *** considering quantum confinement effects,the electron density becomes smaller while the threshold voltage becomes *** results show that this model is applicable from the subthreshold region to the stronginversion region in different channel doping conditions.

关键词： surrounding gate quantum-confinement effects potential energy MOSFET

Dry Friction Characteristics of Ti-6Al-4V Alloy under High Sliding Velocity

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 Wuhan university of Technology(materials Science) 2007年第4期22卷 582-585页

作者：邱明 school of Mechatronic engineering Henan University of Science and Technology Theory of Lubrication and Bearing Institute Xi'an Jiaotong UniversityXi'an 710049China

Tribological behaviours of Ti-6Al-4V alloy pins sliding against GCr15 steel discs over a range of contact pressures （0.3.-1.3. MPa） and sliding velocities （3.-70 m/s） were investigated using a pin-on-disc tribometer under unlubricated conditions. The wear mechanisms and the wear transition were analyzed based on examinations of worn surfaces using SEM, EDS and XRD. When the velocity increases, the friction coefficient and the wear rate of the Ti-6Al-4V alloy show typical transition features, namely, the critical values of sliding velocities for 0.3. and 0.67 MPa are 60 and 40 m/s, respectively. The experimental results reveal that the tribological behaviours of Ti-6Al-4V alloys are controlled by the thermal-mechanical effects, which connects with the friction heat and hard particles of the pairs. A tribolayer containing mainly Ti oxides and V oxides is formed on the worn surface of Ti-6Al-4V alloy.

关键词： Ti alloy dry sliding friction behavior contact temperature wear mechanism

Crystal structures and electronic properties of BaC_2.isomers by theoretical study based on DFT

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2008年第6期51卷 545-550页

作者： FENG Jing1,xiAO Bing2.& CHEN JingChao1 1 Key Laboratory of Advanced materials of Precious-Nonferrous Metals,Education Ministry of china,and Key Lab of Advanced materials of Yunnan Province,Kunming university of Science and Technology,Kunming 650093.china 2.school of materials Science and engineering,xi’an jiaotong university,xi’an 710049,china 1. Key Laboratory of Advanced materials of Precious-Nonferrous Metals Education Ministry of China Kunming China 3. Key Lab of Advanced materials of Yunnan Province Kunming University of Science and Technology Kunming 650093 China 2. school of materials Science and {2. Xi’an Jiaotong University Xi’an 710049 China

Band structures and electronic properties of two BaC2.isomers were calculated by using density func-tional theory(DFT) *** ionic bond features are all typical between cation(Ba) and anion clusters(C2. in both structures of the ***,a much stronger covalent bond exists in anion clusters which can be seen by inspecting the electron distribution contour that has a dull bell like shape between two carbon *** shortest distance between Ba2. and C2.? and the bond length in anion clusters are different in these isomers of BaC2.which are 0.2.45 nm and 0.1185 nm for the structure with the I4/mmm space group and 0.2.44 and 0.113. nm with the C2.c type,*** structures were clarified by combining the DOS to indicate the ionic bonding features more *** analysis provided further evidence on these *** calculation results reveal that the transition temperature of these two polymorphs of BaC2.locates near 13.0}K,which is consistent with the recent experimental results.

关键词： functional materials metal diaries phase transition electron density first principle calculation orbital bonding state