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Correlation of electromagnetic radiation emitted from coal or rock to supporting resistance

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Mining Science and Technology 2009年第3期19卷 317-320页

作者： JIA hui-lin WANG En-yuan SONG Xiao-yan ZHANG Hong-jie li zhong-hui School of Safety Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

More accurate forecasting of rock burst might be possible from observations of electromagnetic radiation emitted in the *** analyzed experimental observations and field data from the Muchengjian coal mine to study the relationship between electromagnetic radiation signal intensity and stress during the fracturing of coal, or rock, and samples under *** results show that the signal intensity is positively correlated with *** addition, we investigated the change in the electromagnetic radiation intensity, the supporting resistance in a real coal mine environment, and the coal or rock stress in the mining *** data analysis indicates that:1) electromagnetic radiation intensity can accurately reflect the distribution of stress in the mining area;and, 2) there is a correlation between electromagnetic radiation intensity and supporting *** research has some practical guiding significance for rock burst forecasting and for the prevention of accidents in coal mines.

关键词： electromagnetic radiation rock burst supporting resistance coal or rock

Post-processing of chitosan based nanofibers prepared by electrospinning

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Post-processing of chitosan based nanofibers prepared by ele...

Flow stress behavior of high-purity Al-Cu-Mg alloy and microstructure evolution

第八届中国功能材料及其应用学术会议

作者： SUN Kang GE Yuan-xin li zhong-hui ZHANG Xiao-lin Institute of Applied Chemistry Chengdu normal university Environmental monitoring station of Minhang district

ISBN: (纸本)9783037859698

Recently,electrospinning of nanofibers based on chitosan has been widely studied and numerous chitosan based nanofibers have been prepared,for the enormous possibilities of applications in various areas such as filtration,enzyme immobilization,tissue engineering,wound dressing,drug delivery,and *** most of the chitosan based nanofibers are soluble in aqueous solutions and the other properties such as mechanical properties are not suitable for the further *** is necessary to improve the properties of chitosan based *** post-processing has been done to the chitosan based nanofibers and many post-processing products have *** article discusses the post-processing of the chitosan based nanofibers involving methods,mechanisms,changes of nanofiber properties,and applications of the post-processing products in *** post-processing is divided into alkali treatment,crosslinking,and functionalizing.

关键词： chitosan nanofiber electrospinning postprocessing application

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Journal of Central South University 2015年第3期22卷 815-820页

作者：李立李慧中梁霄鹏黄岚洪涛 School of Materials Science and Engineering Central South University State Key Laboratory of Powder Metallurgy (Central South University) Key Laboratory of Nonferrous Metallic Materials Science and Engineering of Ministry of Education(Central South University) Xinjiang Joinworld Co. Ltd.

The flow stress behavior of high-purity Al-Cu-Mg alloy under hot deformation conditions was studied by Gleeble-1500,with the deformation temperature range from 300 to 500 °C and the strain rate range from 0.01 to 10 s-1. From the true stress-true strain curve, the flow stress increases with the increasing of strain and tends to be constant after a peak value, showing dynamic recover, and the peak value of flow stress increases with the decreasing of deformation temperature and the increasing of strain *** the strain rate is 10 s-1 and the deformation temperature is higher than 400 °C, the flow stress shows dynamic recrystallization characteristic. TEM micrographs were used to reveal the evolution of microstructures. According to the processing map at true strain of 0.7, the feasible deformation conditions are high strain rate(>0.5 s-1) or 440-500 °C and 0.01-0.02 s-1.

关键词： high-purity Al-Cu-Mg alloy hot compression flow stress processing map

AlGaN/GaN HEMTs on 4-Inch Silicon Substrates in the Presence of 2.7-μm -Thick Epilayers with the Maximum Off-State Breakdown Voltage of 500 V

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Chinese Physics Letters 2014年第3期31卷 129-132页

作者： YU Xin-Xin NI Jin-Yu li zhong-hui KONG Cen ZHOU Jian-Jun DONG Xun PAN Lei KONG Yue-Chan CHEN Tang-Sheng Science and Technology on Monolithic Integrated Circuits and Modules Laboratory Nanjing Electronic Devices Institute Nanjing 210016

We report on the high breakdown performance of AlGaN/GaN high electron mobility transistors （HEMTs） grown on 4-inch silicon substrates. The HEMT structure including three Al-content step-graded AlGaN transition layers has a total thickness of 2.7 μm. The HEMT with a gate width WG of 300 μm acquires a maximum off-state breakdown voltage （BV） of 550 V and a maximum drain current of 527 mA/mm at a gate voltage of 2 V. It is found that BV is improved with the increase of gate-drain distance LGD until it exceeds 8 μm and then BV is tended to saturation. While the maximum drain current drops continuously with the increase of LGD. The HEMT with a WG of 3 mm and a LGD of 8 μm obtains an off-state BV of 500 V. Its maximum leakage current is just 13 μA when the drain voltage is below 400 V. The device exhibits a maximum output current of 1 A with a maximum transconductance of 242 mS.

关键词： HIGH electron mobility transistors RESEARCH SIliCON -- Research GALliUM nitride SEMICONDUCTOR doping PHYSICS research

Pretreatment with interleukin-33 reduces warm hepatic ischemia/ reperfusion injury in mice

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Chinese Medical Journal 2013年第10期126卷 1855-1859页

作者： li Shu ZHU Feng-xue ZHANG Hong-bin li hui AN You-zhong Department of Critical Care Medicine Peking University People'sHospital Beijing 100044 China

Background Interleukin （IL）-33 is a recently identified member of the IL-1 family that binds to the receptor, ST2L. This study examined IL-33 production in mouse liver and investigated its role in hepatic ischemia/reperfusion （I/R） injury. Methods Male BALB/c mice （（22＋3） g） were subjected to 90 minutes partial hepatic ischemia, followed by 6 hours reperfusion. First, mice were randomized into two groups： control group （laparotomy only, without blocking blood supply） and ischemia model group. IL-33 mRNA and serum protein levels were measured at 30, 60, 90 minutes after ischemia and 2 and 6 hours after reperfusion. Second, mice were randomized into four groups： control, model （injection of rabbit IgG polyclonal antibody）, recombinant IL-33 intervention and anti-ST2L antibody intervention group. Mice were sacrificed 6 hours after reperfusion. liver pathology was observed via transmission electron microscopy. Serum aspartate aminotransferase （AST）, alanine aminotransferase （ALT）, IL-4, IL-5, IL-13, interferon-y （IFN-y） and tumor necrosis factor-a （TNF-a） levels were measured. Results Levels of IL-33 mRNA and protein did not change during ischemia （P 〉0.05） but increased significantly during reperfusion （P 〈0.05）. After reperfusion for 6 hours, serum levels of ALT, AST, IL-4, IL-5, IL-13, IFN-~ and TNF-a were significantly increased （P 〈0.05）, and hepatocellular ultrastructure was damaged. Pretreatment with IL-33 attenuated severity of liver damage compared with controls, but pretreatment with anti-ST2L antibody increased severity. Serum levels of IL-4, IL-5 and IL-13 protein increased whereas IFN-y decreased following IL-33 pretreatment. Pretreatment with anti-ST2L antibody significantly decreased serum IL-4, IL-5, IL-13 levels and increased serum IFN-r levels compared with controls （P 〈0.05）. There was no change in the level of TNF-a. Conclusion IL-33 is produced systematically and locally in liver during I/R injury. Pretreatment with IL-33 is therapeutic for hepatic

关键词： liver ischemia/reperfusion T helper lymphocyte,interleukin-33

Effect of forging on the microstructure and texture of a high Nb containing γ-TiAl alloy

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Journal of Central South University 2024年第6期31卷 1763-1773页

作者： TAO hui li hui-zhong WANG li ZHOU Rui CHE Yi-xuan CHEN Yong-hui liANG Xiao-peng School of Materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Metal Materials Science and Engineering Central South UniversityChangsha 410083China Department of Materials Science and Engineering City University of Hong KongKowloon 999077Hong KongChina

The effect of forging on the microstructure and texture evolution of a high Nb containing Ti-45Al-7Nb-0.3W(at.%)alloy was investigated by X-ray diffractometer(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The results show that the as-cast alloy is mainly composed of α_(2)/γ lamellar colonies with a mean size of 70μm,but the hot-forged pancake displays a near duplex microstructure(DP).Kinking and bending of lamellar colonies,deformation twinning and dynamic recrystallization(DRX)occur during hot ***,dense dislocations in theβphase after forging suggest that the high-temperature β phase with a disordered structure is favorable for improving the hot-workability of the *** the common TiAl casting texture,the solidification process of the investigated as-cast alloy with high Nb content is completely via the β phase region,resulting in the formation of aγ fiber texture where theγ aligns parallel to the heat-flow *** comparison,the relatively strongand weaktexture components in the as-forged alloy are attributed to the deformation *** annealing,static recrystallization occurs at the twin boundary and intersections,which weakens the deformation texture.

关键词： high Nb containingγ-TiAl alloy forging microstructure texture βphase

AE waveform characteristics of rock mass under uniaxial loading based on Hilbert-Huang transform

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Journal of Central South University 2021年第6期28卷 1843-1856页

作者： li Xue-long CHEN Shao-jie liU Shu-min li zhong-hui Mine Disaster Prevention and Control-Ministry of State Key Laboratory Breeding Base Shandong University of Science and TechnologyQingdao 266590China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyXuzhou 221116China College of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 266590China State Key Laboratory of Coal Mine Disaster Dynamics and Control College of Resource and Safety EngineeringChongqing UniversityChongqing 400030China

Acoustic Emission(AE)waveforms contain information on microscopic structural features that can be related with damage of coal rock *** this paper,the Hilbert-Huang transform(HHT)method is used to obtain detailed structural characteristics of coal rock masses associated with damage,at different loading stages,from the analyses of the characteristics of AE *** results show that the HHT method can be used to decompose the target waveform into multiple intrinsic mode function(IMF)components,with the energy mainly concentrated in the c1−c4 IMF components,where the c1 component has the highest frequency and the largest amount of *** the loading continues,the proportion of energy occupied by the low-frequency IMF component shows an increasing *** the initial compaction stage,the Hilbert marginal spectrum is mainly concentrated in the low frequency range of 0−40 *** plastic deformation stage is associated to energy accumulation in the frequency range of 0−25 kHz and 200−350 kHz,while the instability damage stage is mainly concentrated in the frequency range of 0−25 *** 20 kHz,the instability damage reaches its maximum *** is a relatively clear instantaneous energy peak at each stage,albeit being more distinct at the beginning and at the end of the compaction *** the effective duration of the waveform is short,its resulting energy is small,and so there is a relatively high value from the instantaneous energy *** waveform lasts a relatively long time after the peak that coincides with failure,which is the period where the waveform reaches its maximum energy *** Hilbert three-dimensional energy spectrum is generally zero in the region where the real energy is *** addition,its energy spectrum is intermittent rather than *** is therefore consistent with the characteristics of the several dynamic ranges mentioned above,and it indicates more clearly the low-frequency energy concentration in the critical sta

关键词： acoustic emission waveform Hilbert-Huang transform coal rock

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碳酸盐岩地层破裂压力预测新模型及其应用

中国石油大学学报（自然科学版） 2010年第2期34卷 71-73页

作者：崔杰李忠慧中国石油大学地球资源与信息学院山东东营257061 胜利油田钻井工艺研究院山东东营257017 长江大学油气钻采工程湖北省重点实验室湖北荆州434023 长江大学石油工程学院湖北荆州434023

海相碳酸盐岩地层原生孔隙较少而裂缝较发育,利用测井资料计算其破裂压力难度较大。依据弹性力学原理和岩层破裂机制,综合考虑三向地应力及地层特征对地层破裂压力的影响,建立一种新的适合海相碳酸盐岩地层的破裂压力计算模型。川东北... 详细信息

海相碳酸盐岩地层原生孔隙较少而裂缝较发育,利用测井资料计算其破裂压力难度较大。依据弹性力学原理和岩层破裂机制,综合考虑三向地应力及地层特征对地层破裂压力的影响,建立一种新的适合海相碳酸盐岩地层的破裂压力计算模型。川东北通南巴构造上5口井的应用结果表明,利用该模型计算得到的破裂压力值与实测值误差较小,能够满足工程计算要求。

关键词：碳酸盐岩破裂压力计算模型弹性力学

基于COPS的PIM-SM多播转发树切换策略的研究

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计算机工程与科学 2009年第6期31卷 1-3,11页

作者：李钟辉清华大学信息网络工程研究中心北京100084

该文对PIM-SM多播路由协议现有的多播转发树切换策略及其配置方式进行了较为全面的分析,针对其所存在的问题提出了基于COPS协议的PIM-SM多播转发树切换策略模型。该模型中引入了COPS协议的客户/服务器体系结构,从而实现了切换策略的集... 详细信息

该文对PIM-SM多播路由协议现有的多播转发树切换策略及其配置方式进行了较为全面的分析,针对其所存在的问题提出了基于COPS协议的PIM-SM多播转发树切换策略模型。该模型中引入了COPS协议的客户/服务器体系结构,从而实现了切换策略的集中管理与配置。同时,通过对多播转发树及其相关特性的深入研究,设计出两种具体的切换策略实例。在对该模型的模拟和测试中,对实验所获取的测试结果分析表明,基于COPS的切换策略模型具有较高的灵活性和适应性,所提出的两种切换策略可以有效地改善网络的整体性能和稳定性,达到了预期效果。

关键词：多播策略 PIM-SM COPS 转发树切换