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Effect of local non-convexity on the critical shear strength of granular materials determined via the discrete element method

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Particuology 2020年第5期18卷 105-112页

作者： Zhihong Nie Shunkai Liu wei hu Jian Gong School of Civil Engineering Central South UniversityChangshaHunan 410075China hunan Province Key Laboratory of Geotechnical Engineering Stability Control and Health Monitoring Hunan University of Science and TechnologyXiangtanHunan 411201China School of Hydraulic Engineering Changsha University of Science and Technology Changsha 410114China

Multi-sphere clumps are commonly used to simulate non-spherical particles in discrete element method *** is of interest whether the degree of local non-convexity λ affects the mechanical behaviour of granular materials with the same non-convexity η.A series of discrete-element-method biaxial shear tests are conducted on rough particle packings with rη=0.075 and different λ values(ranging from 0.134 to 0.770).The microscale results show that the contact type changes with an increase in λ.However,the critical strength is independent of λ.The evaluation of the contributions of different contact types to the critical shear strength and a detailed analysis of the anisotropies help clarify the microscopic mechanisms that result in the independence of the critical shear strength from λ.

关键词： Multi-sphere clump Local non-convexity Discrete element method Biaxial shear test Contact type Critical shear strength

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Science in China(Series F) 2009年第4期52卷 617-626页

作者： wei YongZhuang hu YuPu Key Laboratory of Computer Networks & Information Security of Ministry of Education Xidian University Xi'an 710071 China

In this paper, we examine the security of reduced AES-192 and AES-256 against related-key rectangle attacks by exploiting the weakness in the AES key schedule. We find the following two new attacks： 9-round reduced AES-192 with 4 related keys, and 10-round reduced AES-256 with 4 related keys. Our results show that related-key rectangle attack with 4 related keys on 9-round reduced AES-192 requires a data complexity of about 2^101 chosen plaintexts and a time complexity of about 2^174.8 encryptions, and moreover, related-key rectangle attack with 4 related keys on 10-round reduced AES-256 requires a data complexity of about 2^97.5 chosen plaintexts and a time complexity of about 2^254 encryptions. These attacks are the first known attacks on 9-round reduced AES-192 and 10-round reduced AES-256 with only 4 related keys. Furthermore, we give an improvement of the 10-round reduced AES-192 attack presented at FSE2007, which reduces both the data complexity and the time complexity.

关键词： block cipher Advanced Encryption Standard related-key rectangle attack time complexity

Integration mechanisms of transgenes and population fitness of GH transgenic fish

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Science China(Life Sciences) 2010年第4期53卷 401-408页

作者： hu wei &Zhu ZuoYan State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China

It has been more than 20 years since the first batch of transgenic fish was produced. Five stable germ-line transmitted growth hormone (GH) transgenic fish lines have been generated. This paper reviews the mechanisms of integration and gene targeting of the transgene, as well as the viability, reproduction and transgenic approaches for the reproductive containment of GH-transgenic fish. Further, we propose that it should be necessary to do the following studies, in particularly, of the breeding of transgenic fish: to assess the fitness of transgenic fish in an aqueous environment with a large space and a complex structure; and to develop a controllable on-off strategy of reproduction in transgenic fish.

关键词： transgene integration mechanism GH transgenic fish population fitness

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基于机器视觉的电极片缺陷检测方法研究

印刷与数字媒体技术研究 2025年第1期 101-109页

作者：吴中虎胡伟河南理工大学电气工程与自动化学院焦作454003

本研究将机器视觉与锂电池模切设备相结合,提出一种基于Canny算法改进的极片缺陷边缘检测方法。首先采用灰度拉伸的自适应图像增强算法,增强图像信息;其次针对对比度较低的缺陷使用引导滤波对图像进行降噪,有效避免了高斯滤波在降噪时... 详细信息

本研究将机器视觉与锂电池模切设备相结合,提出一种基于Canny算法改进的极片缺陷边缘检测方法。首先采用灰度拉伸的自适应图像增强算法,增强图像信息;其次针对对比度较低的缺陷使用引导滤波对图像进行降噪,有效避免了高斯滤波在降噪时对梯度变化平缓的边缘造成梯度消失的问题;采用基于Sobel算法的3×3梯度模板使用一阶有限差分计算4个方向偏导数阵列得到梯度的幅值与方向角;最后,基于迭代法和NIBLACK算法自动获取图像的高、低阈值,通过双阈值去掉伪边缘,并将两种算法的检测结果逻辑与运算进行边缘融合。经实测,本算法对极片表面低对比度的缺陷边缘提取识别率可达97.95%,相较与传统Canny算法提高了17.35%以上。且该算法系统可以在线稳定运行,满足实际生产需求。

关键词：机器视觉引导滤波 Canny算法缺陷检测

Efficient dechlorination of 2,4-dichlorophenol in an aqueous media with a mild pH using a Pd/TiO2NTs/Ti cathode

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Frontiers of Environmental Science & Engineering 2015年第5期9卷 919-928页

作者： Jiangkun DU Jianguo BAO wei hu School of Environmental Studies China University of Geosciences Wuhan 430074 China

In this study, palladium-loaded titania nano- tubes was fabricated on a titanium plate （Pd/TiO2NTs/Ti） for efficient electrodechlorination of 2,4-chlorophenol with a mild pH condition. The nature of PdYTiO2NTs/Ti electrodes was characterized by field-emission scanning electron microscope （FESEM）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, and cyclic voltammetry （CV） techniques. The characterization results indicated the generation of Pd~ nanoparticles which were evenly dispersed on titania nanotubes arrays on the Pd/ TiO2NTs/Ti surface. An effective degradation efficiency of up to 91% was achieved within 60 min at cathode potential of -0.7 V （vs. SCE） and initial pH of 5.5. The effects of the applied cathode potential and initial pH on the degradation efficiency were studied. A near neutral condition was more favorable since very low and very high pHs were not conducive to the dechlorination process. Furthermore, the intermediates analysis showed that the Pd/TiO2NTs/Ti electrode could completely remove chlor- ine from 2, 4-dichlorophenol since only phenol was detected as the byproduct and the concentration of released chlorine ions indicated near-complete dechlorination. This work presents a good alternative technique for eliminating persistent chlorophenols in polluted wastewater without maintaining strong acidic environment.

关键词： Pd/TiO2NTs/Ti cathode chlorophenols electrocatalytic dechlorination wastewater treatment

Desulfurizer desulphurization kinetics by the injection method

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Journal of University of Science and Technology Beijing 2008年第4期15卷 375-378页

作者： wei Wu Zhijun Han Yanbin hu wei Wu2 Metallurgical Technology Institute Central Iron ＆ Steel Research Institute Beijing 100081 China

To obtain a better desulphurization effect in hot metal, suitable desulfurizers should be selected first according to thermodynamics. However, the effect of desulphurization is also strongly affected by kinetics. The conditions of different desulfurizers （Mg, CaC2, and lime） penetrating into hot metal, the rising up velocity in iron melt, residence time, and dissolving time are theoretically calculated and analyzed. The results are helpful to select the desulphurization process and equipment and to improve the desulphurization effect.

关键词： hot metal desulphurization desulphurization kinetics injection

Direct synthesis of diaryl sulfides by copper-catalyzed coupling of aryl halides with aminothiourea

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Chinese Chemical Letters 2012年第4期23卷 391-394页

作者： Xiang Mei Wu wei Ya hu Department of Chemistry College of ScienceLishui UniversityLishui 323000China

An efficient and simple protocol of copper-catalyzed C-S bond formation between aryl halides and inexpensive and commercially available aminothiourea is reported.A variety of symmetrical diaryl sulfides can be synthes... 详细信息

关键词： Copper Diaryl sulfide Aryl halide Aminothiourea

Modeling Topic-Based human Expertise for Crowd Entity Resolution

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Journal of Computer Science & Technology 2018年第6期33卷 1204-1218页

作者： Sai-Sai Gong wei hu wei-Yi Ge Yu-Zhong Qu State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210023 China Science and Technology on Information Systems Engineering Laboratory Nanjing 210007 China

Entity resolution （ER） aims to identify whether two entities in an ER task refer to the same real-world *** ER uses humans, in addition to machine algorithms, to obtain the truths of ER tasks. However, inaccurate orerroneous results are likely to be generated when humans give unreliable judgments. Previous studies have found thatcorrectly estimating human accuracy or expertise in crowd ER is crucial to truth inference. However, a large number ofthem assume that humans have consistent expertise over all the tasks, and ignore the fact that humans may have variedexpertise on different topics （e.g., music versus sport）. In this paper, we deal with crowd ER in the Semantic Web *** identify multiple topics of ER tasks and model human expertise on different topics. Furthermore, we leverage similartask clustering to enhance the topic modeling and expertise estimation. We propose a probabilistic graphical model thatcomputes ER task similarity, estimates human expertise, and infers the task truths in a unified framework. Our evaluationresults on real-world and synthetic datasets show that, compared with several state-of-the-art approaches, our proposedmodel achieves higher accuracy on the task truth inference and is more consistent with the human real expertise.

关键词： entity resolution crowdsourcing human expertise topic modeling task similarity

Asymmetric Polymerization of N-Vinylcarbazole with Optically Active Anionic Initiators

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Chinese Journal of Polymer Science 2015年第11期33卷 1618-1624页

作者： wei hu 曹靖 Yi-ling huang Sai Liang Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education College of ChemistryXiangtan University

The anionic polymerization of N-vinylcarbazole（NVC） by using optically active anionic initiators such as the lithium salts of（S）-1-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-1-FIDH） and（S）-2-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-2-FIDH） and complexes of（-）-Sparteine with n-butylithium（n-Bu Li-（-）-Sp） or fluorenyl lithium（FILi-（-）-Sp） was achieved. The yield and specific rotation of poly（N-vinylcarbazole）s（poly（NVC）s） were considerably affected by the molar ratio of（S）-FIDH to NVC. The highest yield and specific rotation were obtained with Li-（S）-1-FIDH as an initiator, with a molar ratio of monomer and initiator [M]/[I] = 10/1. The effects of the chiral initiators, type of solvent and the polymerization temperature were investigated. The obtained optical activity of polymers was attributed to asymmetric induction of the chiral initiators.

关键词： Helical polymer Anionic polymerization Chiral carbon anionic initiator N-vinylcarbazole