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INFILTRATION KINETICS MODEL OF LIQUID METAL INTO A FIBROUS PREFORM IN CENTRIFUGAL ACCELERATING FIELD

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Chinese Journal of Mechanical Engineering 2001年第4期14卷 293-296页

作者： Zhang Xinping,Yu Sirong,he zhenming (College of Materials Science and Engineering,Jilin University) 吉林大学吉林

The infiltration kinetics of the metal melt into a fibrous preform in centrifugal accelerating field is analyzed on the basis of Darcy's law and the assumption that the fibrous preform is treated as 'bundle of capillaries' The critical rotating speed is analyzed with the established model The influences of the metal melt mass,the rotating speed of the equipment,the casting height, the original outer radius of the metal melt and the fibrous volume fraction in fibrous preform on infilatration are studied The results show that the critical rotating speed is dependent on critical pressure, casting height, metal melt mass and the character of fibrous preform With the increase in the metal melt mass, rotating speed of the equipment and original outer radius of the metal melt, or the decrease in casting height and fibrous volume fraction in fibrous of the metal melt,or the decrease in casting height and fibrous volume fraction in fibrous preform,infiltration of metal melt for fibrous preform becomes easier.

关键词： Centrifugal accelerating field Metal melt Fiber Infiltration kinetics Metal matrix composite

A modified smoothed particle hydrodynamics method considering residual stress for simulating failure and its application in layered rock mass

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Journal of Mountain Science 2024年第6期21卷 2091-2112页

作者： XIA Chengzhi SHI zhenming KOU Huanjia Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China

Residual strength is an indispensable factor in evaluating rock fracture,yet the current Smoothed Particle Hydrodynamics(SPH)framework rarely considers its influence when simulating *** improved cracking strategy considering residual stress in the base bond SPH method was proposed to simulate failures in layered rocks and slopes and verified by experimental results and other simulation methods(i.e.,the discrete element method).Modified Mohr–Coulomb failure criterion was applied to distinguish the mixed failure of tensile and *** fracture markψwas introduced to improve the kernel function after tensile damage,and the calculation of residual stress after the damage was derived after shear *** simulations were carried out to evaluate its performance under different stress and scale conditions and to verify its effectiveness in realistically reproducing crack initiation and propagation and coalescence,even fracture and *** results indicate that the improved cracking strategy precisely captures the fracture and failure pattern in layered rocks and rock *** residual stress of brittle tock is correctly captured by the improved SPH *** improved SPH method that considers residual strength shows an approximately 13%improvement in accuracy for the safety factor of anti-dip layered slopes compared to the method that does not consider residual strength,as validated against analytical *** infer that the improved SPH method is effective and shows promise for applications to continuous and discontinuous rock masses.

关键词： Smoothed particle hydrodynamics Cracking strategy Residual stress Layered rock Crack propagation

CONSTITUTIONAL DIAGRAM OF Fe-Mn-C ALLOYS AFTER SOLUTION TREATMENT AT 1000℃

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Acta Metallurgica Sinica(English Letters) 1992年第8期5卷 94-98页

作者： LI Shaoxiong he zhenming ZHAO Yuguang ZHAO Yuqian SHI Zhongliang Jilin University of Technology,Changchun,China

On the basis of experimental results of 76 points of composition and previous relevant conclu- sions,a relatively complete constitutional diagram of solid solution treating Fe-Mn-C sys- tem alloy at 1000℃ has been constructed with austenite zones of different *** chemical composition range and structure change of steels with various Mn have also been ***,the reasonable selection of composition and structure may be available for the manganese steel with commercial purposes.

关键词： constitutional diagram Fe-Mn-C alloy austenite

Alternate disinfection approaches or raise disinfectant dosages for sewage treatment plants to address the COVID-19 pandemic?From disinfection efficiency,DBP formation,and toxicity perspectives

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Frontiers of Environmental Science & Engineering 2024年第9期18卷 115-128页

作者： Xiaobin Liao Xinyue Liu Yueyun he Xueping Tang Ruanjunjie Xia Yongjun Huang Wenhua Li Jing Zou zhenming Zhou Mazhan Zhuang Institute of Municipal and Environmental Engineering College of Civil EngineeringHuaqiao UniversityXiamen 361021China Xiamen Institute of Environmental Science Xiamen 361021China College of Biomedical Sciences Huaqiao UniversityXiamen 361021China

During the COVID-19 pandemic,most sewage treatment plants increased disinfectant dosages to inactivate pathogenic viruses and microorganisms more ***,this approach also led to the production of more disinfection by-products(DBPs).To ensure both disinfection efficiency and a reduction in DBP formation,new disinfection protocols are *** this study,the disinfection efficiency,DBP amounts,and toxicity changes resulting from ozone(O_(3)),ultraviolet(UV),chlorine(Cl_(2)),and their combined processes were *** results demonstrated that the O_(3)/UV/Cl_(2)combination achieved the highest disinfection *** produced the most DBPs,whereas UV treatment reduced the formation of trihalomethane(THM),halogenated ketones(HKs),haloacetic acids(HAA),dichloroacetonitrile(DCAN)and N-nitrosodimethylamine(NDMA)by 45.9%,52.6%,82.0%,67.95%,and 47%,respectively.O_(3)also significantly reduced their production by 99.1%,91.1%,99.5%,100%,and 35%.Intracellular organic matter(IOM)was identified as the primary DBP precursors,producing 2.94 times more DBPs than extracellular organic matter(EOM).The increased DBP formation during chlorination was attributed to IOM leakage and cell membrane damage,which was verified using scanning electron microscopy(SEM).The toxicities of DBPs were evaluated for six disinfection methods,revealing inconsistent *** overall toxicities were assessed using zebrafish embryo *** evaluations indicated that chlorination alone was the least favorable *** addition,the toxicities followed a sequence:Cl_(2)≈O_(3)/Cl_(2)>O_(3)>O_(3)/UV/Cl_(2)>UV>UV/Cl_(2).These findings can serve as a reference for sewage treatment plants in selecting appropriate disinfection methods to manage the COVID-19 epidemic from comprehensive perspective.

关键词： Sewage bacteria Disinfection by-products Toxicity Ozonation UV Chlorination

A New Scheme of Bit-plane Coding in MPEG-4

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通讯和计算机（中英文版） 2005年第5期2卷 51-55页

作者： Feng Wang Guangxi Zhu zhenming Zhang Yejun he Dept. of Electronics and Information Engineering Huazhong University of Science ＆ Technology Wuhan 430074 China

In the paper, authors propose a new bit-plane coding scheme of the DCT(Discrete Cosine Transform) coefficients residues which divide an 8 8 block of the DCT coefficients residues into a positive coefficients block and a negative coefficients block, and subsequently encodes the two coefficients blocks with bit-plane coding. The number of (RUN, EOP) symbols in each bit-plane remains the same in proposed and original schemes. As the number of non-zero coefficients does not change in the two schemes, to differentiate the positive and negative bit-plane coefficients, only one flag bit must be inserted between the positive bit-plane and the negative bit-plane. Therefore, at most six flag bits are used in a block. As a result, the total coding bits using the signs of all DCT coefficients residues are decreased to improve coding efficiency.

关键词：二进制译码参数编译程序计算机软件

Mechanism of the Interfacial Reaction of AI_2O_3/Medium Mn Steel Containing Nb

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Journal of Materials Science & Technology 1993年第4期9卷 304-306页

作者： Sirong YU Yaohui LIU zhenming he Dept.of Metallic Materials Engineering,Jilin University of Technology,Changchun,130022,China

The mechanism of the interfacial reaction of Al_2O_3/medium Mn steel containing Nb was studied by means of the observation on the interfacial reaction phenomenon of Al_2O_3/medium Mn steel,and the analyses on the interracial *** results show that when T≥1550℃,the interfacial reac- tion of Al_2O_3/medium Mn steel containing Nb *** the medium Mn steel matrix,Nb exists in the form of *** are the nucleating base of CO gas bubbles.

关键词： Nb medium Mn steel Al_2O_3 interfacial reaction

新型团球状共晶体奥氏体贝氏体钢及其抗冲击磨料磨损特性

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钢铁 1998年第3期33卷 46-50页

作者：许振明姜启川蔡英文何镇明西北工业大学吉林工业大学

研究了新型钢的化学成分、组织结构、力学性能，重点考察了其冲击磨料磨损特性。结果表明，在中、低冲击工况下团球状共晶体能奥—贝钢（Ａｕｓｔｅｎｉｔｅ－ＢａｉｎｉｔｅＳｔｅｅｌｗｉｔｈＮｏｄｕｌａｒＥｕｔｅｃｔｉｃｓ，简称... 详细信息

研究了新型钢的化学成分、组织结构、力学性能，重点考察了其冲击磨料磨损特性。结果表明，在中、低冲击工况下团球状共晶体能奥—贝钢（Ａｕｓｔｅｎｉｔｅ－ＢａｉｎｉｔｅＳｔｅｅｌｗｉｔｈＮｏｄｕｌａｒＥｕｔｅｃｔｉｃｓ，简称ＡＢＮＥ钢）的耐磨性均优于奥—贝钢、奥—贝球铁、团球状碳化物中锰钢，主要原因是在磨损过程中团球状共晶体能有效地减轻磨料侵入深度和阻碍微切削的作用，同时奥—贝基体具有足够的强韧性，以使冲击形成的挤压唇能承受更多的塑性变形而不脱落。

关键词：团球状共晶体奥-贝钢耐磨性

Low-resolution Kramers-Kronig detection system with error-feedback noise shaping

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Science China(Information Sciences) 2024年第5期67卷 259-269页

作者： Xiangyong DONG zhenming YU Hongyu HUANG Kaixuan SUN Kun XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

In this paper, we investigated the effects of error-feedback noise shaping(EFNS) on a lowresolution Kramers-Kronig(KK) detection system for the first time. Both 16-ary quadrature amplitude modulation(16-QAM) and 64-ary quadrature amplitude modulation(64-QAM) were considered in the experiment. The carrier tone was added on the transmitter side using the virtual carrier-assisted single sideband(VCA-SSB) method to meet the minimum phase(MP) condition. Under the MP condition, KK detection only needs the intensity of the optical signal to be detected by one photodiode(PD) to retrieve the phase information. However, the virtual carrier tone increases the carrier-to-signal power ratio(CSPR), which results in a high peak-to-average power ratio(PAPR) at the transmitter, causing an increase in quantization noise. To mitigate quantization noise in the low-resolution KK detection system, EFNS was applied. The application of EFNS increased the optimal CSPR of the KK detection system and improved receiver sensitivity. Using a 4-bit DAC and the EFNS, 80 km transmission was achieved in the 60-Gbit/s 64-QAM KK detection system.

关键词： optical fiber communications Kramers-Kronig receiver error-feedback noise shaping quantization noise carrier-to-signal power ratio

Sensitivity analyses of random cave groups on karst tunnel stability based on water–rock interaction using a novel contact dynamic method

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Underground Space 2024年第5期18卷 162-186页

作者： Chengzhi Xia zhenming Shi Huanjia Kou Shaoqiang Meng Maomao Liu College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China

This paper concentrates on the sensitivity and dynamic simulation of randomly distributed karst cave groups on tunnel stability and connectivity extended ratio based on water–rock interaction using a novel contact dynamic method(CDM).The concept of karst cave group connectivity extended ratio during tunneling and water inrush is *** effects of cave shape and spatial distribution on Qiyueshan tunnel are *** deformation and damage index,and connectivity extended ratio with uniform random karst cave groups are *** results demonstrate that the connectivity extended ratio is verified as a crucial judgment in predicting the safe distance and assessing the stability of the tunnel with the karst cave *** model captures the fracture propagation and contact behavior of rock mass,surface flow,as well as the bidirectional water–rock interaction during the water inrush of Qiyueshan tunnel with multiple caves.A larger cave radius and smaller minimum distance between the cave and tunnel increase the deformation and damage index of the surrounding *** the cave radius and cave area ratio increase,the failure pattern shifts from overall to local *** findings potentially have broad applications in various surface and subsurface scenarios involving water–rock interactions.

关键词： Karst tunnel stability Contact dynamic method Connectivity extended ratio Karst cave groups Qiyueshan tunnel Water-rock interaction