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Effect of acid oxidization of carbon nanotube electrode on the capacitances of double layer capacitors

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Science china(Technological Sciences) 2004年第3期47卷 257-264页

作者： Li Chensha1,wang Dazhi1,LIANG Tongxiang2.wang Xiaofeng1 & LIANG Ji1 1. {2. of mechanical engineering, Tsinghua university,Beijing 100084, china 2. Institute of Nuclear Energy technology, Tsinghua university,Beijng 102.01,china department of mechanical {2. Tsinghua University Beijing 100084 China Institute of Nuclear Energy technology Tsinghua University Beijing 102201 China

Polarizable electrode of electric double layer capacitor was made from carbon nanotubes. The effect of acid oxidation of electrode on the specific capacitance was studied. Oxidation removed the redundant carbon, expanded the pore size and introducedf some kinds of functional groups on the surface of CNTs. The specific capacitance of the electrodes winth organic electrolyte was increased from 2..4 to 49.6 F/g after being oxidized at a volume ratio H2.O4 to HNO3 of 3:1.

关键词： carbon nanotubes, electric double layer capacitor, specific capacitance.

Data Component:An Innovative Framework for Information Value Metrics in the Digital Economy

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china Communications 2024年第5期21卷 17-35页

作者： Tao xiaoming wang Yu Peng Jieyang Zhao Yuelin wang Yue wang Youzheng Hu Chengsheng Lu Zhipeng department of Electronic engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and technology Beijing 100084China china Electronics Corporation Beijing 100084China

The increasing dependence on data highlights the need for a detailed understanding of its behavior,encompassing the challenges involved in processing and evaluating ***,current research lacks a comprehensive structure for measuring the worth of data elements,hindering effective navigation of the changing digital *** paper aims to fill this research gap by introducing the innovative concept of“data components.”It proposes a graphtheoretic representation model that presents a clear mathematical definition and demonstrates the superiority of data components over traditional processing ***,the paper introduces an information measurement model that provides a way to calculate the information entropy of data components and establish their increased informational *** paper also assesses the value of information,suggesting a pricing mechanism based on its *** conclusion,this paper establishes a robust framework for understanding and quantifying the value of implicit information in data,laying the groundwork for future research and practical applications.

关键词： data component data element data governance data science information theory

Tribological Properties of Dimpled Surface Alloying Layer on Carbon Steel

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Journal of Wuhan university of technology(Materials Science) 2009年第2期24卷 218-222页

作者：万轶 department of Materials Science & engineering Nanjing University of Science and Technology department of mechanical and Electrical {2. Yingtian College

The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and depth of 50 rn were distributed in an orbicular array on disc surface. Then the alloying element Mo was sputtered to 45# carbon steel disc surface by means of double glow plasma technology. Diffusion Mo alloying layer with 30min thickness and high hardness up to 0.02. was formed on the disc surface. Tribological experiments of three types samples （smooth, texturing and texturing＋alloying） were conducted with a pin-on-disc tribometer. It is found that the dimpled-samples are most effective for reducing friction in comparison with smooth steel surthces, improving the lubricating state from boundary to hydrodynamic region.

关键词： laser surface texturing double glow plasma surface alloying technology carbon steel tribological performance lubricating state

Failure mechanism and safety control technology of a composite strata roadway in deep and soft rock masses:a case study

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Journal of Mountain Science 2024年第7期21卷 2427-2444页

作者： ZHAO Chengwei ZHOU Hui SUN xiaoming ZHANG Yong MIAO Chengyu wang Jian State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China university of Chinese Academy of Sciences Beijing 100049China State Key Laboratory for GeoMechanics and Deep Underground engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil engineering China University of Mining and Technology(Beijing)Beijing 100083China

The construction of coal mines often encounters deep composite soft rock roadways,which is characterized by significant deformation and poor *** deeply study the failure mechanism and large deformation challenges of a composite strata roadway in deep and soft rock masses,a numerical model of 3DEC tetrahedral blocks was established based on the method of rock quality designation(RQD).The results showed that original support cannot prevent asymmetric failure and large deformation due to the adverse geological environment and unsuitable support *** to the failure characteristics,a coupling support of“NPR bolt/cable+mesh+shotcrete+steel pipe”was proposed to control the stability of the surrounding *** excellent mechanical properties of large deformation(approximately 400 mm)and high constant resistance force(bolt with 180 k N;cable with 350 k N)were evaluated by the tensile *** numerical results showed that the maximum deformation was minimized to 2.3 mm,and the bearing capacity of the surrounding rock of the roadway was *** field test results showed that the maximum deformation of the surrounding rock was 2.0 mm,and the forces of the NPR bolt and cable were stable at approximately 180 k N and 350 k N,*** demonstrated the effectiveness of the coupling support with the NPR bolt and cable,which could be a guiding significance for the safety control of large deformation and failure in deep composite soft rock roadways.

关键词： 3DEC Composite strata roadway Soft rock NPR bolt and cable Asymmetric large deformation

NOVEL METHOD SOLVING NUMERICAL INSTABILITIES IN TOPOLOGY OPTIMIZATION

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Chinese Journal of mechanical engineering 2002年第1期15卷 22-26页

作者： Guo Dongming wang xiaoming Liu Zhenyu {2. of mechanical engineering，Dalian university of technology， Dalian 11602.，china department of Mehanical engineering Dalian University of Technology Dalian 116023

Numerical instabilities are often encountered in FE solution of continuumtopology optimization. The essence of the numerical instabilities is given from the inverse partialdifferential equation (PDE) point of view. On the basis of the strict mathematical theory, a novelmethod, named as window filter and multi-grid method, which solves the numerical instabilities, isproposed. Convergent analyses and a numerical example are presented.

关键词： Topology optimization Gaussian windows Checkerboard pattern

High-temperature oxidation behavior of Al_2._3/TiAl matrix composite in air

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Science china(Technological Sciences) 2009年第5期52卷 1273-1282页

作者： AI TaoTao1,wang Fen2.& FENG xiaoming1 1 {2. of Materials Science and engineering,Shaanxi university of technology,Hanzhong 72.003,china 2.School of Materials Science and engineering,Shaanxi university of Science and technology,Xi’an 71002.,china department of Materials Science and engineering Shaanxi University of Technology Hanzhong China School of Materials Science and engineering Shaanxi University of Science and Technology Xi’an China

The oxidation behavior of Al2.3/TiAl in situ composites fabricated by hot-pressing technology was in-vestigated at 900℃ in static *** results indicate that the mass gains of the composites samples decrease gradually with increasing Nb2.5 content and the inert Al2.3 dispersoids effectively increase the oxidation resistance of the *** higher the Al2.3 dispersoids content,the more pro-nounced the *** primary oxidation precesses obey approximately the linear laws,and the cyclic oxidation precesses follow the parabolic *** oxidized sample containing Ti2.lN and TiAl phases in the scales exhibits excellent oxidation *** oxide scale formed after exposure at 900 ℃ for 12. h is multiple-layered,consisting mainly of an outer TiO2.layer,an intermediate Al2.3 layer,and an inner TiO2.Al2.3 mixed *** the outer layer to the inner layer,TiO2.Al2.3 mixed layer presents the transit of Al-rich oxide to Ti-rich oxide mixed *** the substrate,cross-section micrograph shows a relatively loose layer,and micro-and macro-pores remain on this layer,which is a transition layer and transferres from Al2.3+TiO2.scale to *** thickness of oxide layer is about 2. μ*** is also found that continuous protective alumina scales can not be observed on the surface of oxida-tion *** ions diffuse outwardly to form the outer TiO2.layer,while oxygen ions transport inwardly to form the inner TiO2.Al2.3 mixed *** long-time intensive oxidation exposure,the internal Al2.3 scale has a good adhesiveness with the outer TiO2.*** obvious spallation of the oxide scales *** increased oxidation resistance by the presence of in situ Al2.3 particulates is at-tributed to the enhanced alumina-forming tendency and thin and dense scale ***2.3 particu-lates enhance the potential barrier of Ti ions from M/MO interface to O/MO interface,thereby the TiO2.growth rate decreases,which is also beneficial to improve the oxidation resistance.

关键词： Al2.3/TiAl matrix composite oxidation resistance high temperature

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural Science:Materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, wang Dazhi1, ZHANG Baoyou2. wang Xiaofeng1, CAO Maosheng3 and LIANG Ji1(1. {2. of mechanical engineering, Tsinghua university, Beijing 100084, china 2. Center for Analysis and Measurement, Harbin Institute of technology, Harbin 150001, china 3. School of Material Science and engineering, Tsinghua university, Beijing 100084, china) Dept. of Mech. Eng. Tsinghua Univ. Beijing 100084 China Ctr. for Analysis and Meas. Harbin Inst. of Technol. Harbin 150001 China Sch. of Mat. Sci. and Eng. Tsinghua Univ. Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

STRESS-STRAIN FINITE ELEMENT ANALYSIS AND FATIGUE LIFE PREDICTION FOR BOLTED CONNECTIONS

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Chinese Journal of mechanical engineering 2002年第1期15卷 75-78页

作者： wang Ziqin Xie Qingsheng mechanical {2. department，Guizhou university of technology，Guiyang 550003，china mechanical engineering {2. Guizhou University of Technology Guiyang 550003

A cyclic plasticity model is used into finite element (FE) method to obtainthe details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteriain multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue livesare in favorable agreement with the experimental results for machined bolts.

关键词： Finite element Fatigue Bolted connection

Data classification from the inverse nth power gravitation

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Science china(Information Sciences) 2012年第1期55卷 184-190页

作者： XU HuaRong1,wang XiaoDong1,ZENG ZhiQiang1&FANG Qiu2.1department of Computer Science and {2.,Xiamen university of {2.,Xiamen 36102.,china 2.1} of mechanical engineering,Xiamen university of {2.,Xiamen 36102.,china department of Computer Science and technology Xiamen University of Technology Xiamen China department of mechanical {2. Xiamen University of Technology Xiamen China

By the inverse nth power gravitation in physics,a novel classifier for data classification,called the I-n-PG classifier,is *** the I-n-PG model,training samples from each class are regarded as a system of particles and an I-n-PG field is defined for each class.A test sample belongs to the class whose particle system has the maximum I-n-PG to this test *** on large numbers of real data show that the I-n-PG classifier can provide a good classification *** with the nearest neighbor classifier and SVM,performances of the I-n-PG classifier are always superior/close to the better one of them,and thus the I-n-PG classifier has also a wide range of adaptability to data sets.

关键词： data classification inverse nth power gravitation