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Simulations of Coarsening Behavior for M_(23)C_6 Carbides in AISI H13 Steel

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Journal of Materials Science & Technology 2006年第2期22卷 153-158页

作者： Xinbin HU Mei ZHANG xiaochun wu Lin LI School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Mechanical Engineering Hubei University of Technology Wuhan 430068 China

Based on the local equilibrium assumption, coarsening behavior of M23C6 carbide at 700℃ in H13 steel was simulated by DICTRA software. The results from the calculations were compared with transmission electron microscopy （TEM） observations. The results show the interracial energy for M23C6 in H13 steel at 700℃ is thus probably 0.7J·m^-2, which fits the experiments well. The influence of composition and temperature on the coarsening rate was also investigated by simulations. Simulations show a decrease in the coarsening rate when V/Mo ratio is increased, while the coarsening rate increases with increasing temperature.

关键词： DICTRA Simulation Carbides coarsening AISI H13 steel Interfacial energy

Dynamic load distribution with hop-by-hop forwarding based on max-min one-way delay

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Science China(Information Sciences) 2014年第6期57卷 113-124页

作者： CHEN Fei wu ChunMing WANG Bin QIAN YaGuan wu xiaochun College of Computer Science Zhejiang University College of Science Zhejiang University of Science and Technology College of Information and Electronic Engineering Zhejiang Gongshang University

Load balancing can effectively improve network performance and scalability,but it may cause packet disorder,so worsening the ***,without MPLS to establish the desired end-to-end paths,hop-by-hop routing load balancing is more difficult to achieve than the source routing;however,it can significantly improve network *** this paper,we propose a load balancing scheme with hop-by-hop routing,by using the burstiness features of flows to make sure that the packets of the same flow arrive at the receiving end in *** results show that our algorithm can adapt to the dynamic changes of the end-to-end delay and the routing vector,and also can achieve fine-gained load balancing.

关键词： load balancing adaptive routing multipath routing traffic engineering packet reordering

SLD-MAGIC冷作模具钢的微观组织及切削性能

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上海金属 2024年第4期46卷 53-59页

作者：肖洋吴红庆闵娜吴晓春上海大学材料科学与工程学院上海200444

采用金相显微镜、扫描电子显微镜和能谱仪、透射电子显微镜以及铣削试验,研究了新型SLD-MAGIC冷作模具钢的微观组织及切削性能。结果表明:相较于DC53钢,SLD-MAGIC钢的切削性能更优异;SLD-MAGIC钢回火析出了(Fe,Cr)_(7)C_(3)和Fe_(7)C_(3... 详细信息

采用金相显微镜、扫描电子显微镜和能谱仪、透射电子显微镜以及铣削试验,研究了新型SLD-MAGIC冷作模具钢的微观组织及切削性能。结果表明:相较于DC53钢,SLD-MAGIC钢的切削性能更优异;SLD-MAGIC钢回火析出了(Fe,Cr)_(7)C_(3)和Fe_(7)C_(3)型二次碳化物,其中,小尺寸碳化物数量是DC53钢的1.2倍,而DC53钢中大尺寸及超大尺寸碳化物数量是SLD-MAGIC钢的1.35倍;此外,SLD-MAGIC钢中还含有大量硫化锰夹杂。大量细小碳化物及硫化锰夹杂有利于SLD-MAGIC钢获得优异的切削性能。

关键词：冷作模具钢硫化锰碳化物切削性能

Fault diagnosis of railway point machines based on wavelet transform and artificial immune algorithm

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Transportation Safety and Environment 2023年第4期5卷 117-126页

作者： xiaochun wu Weikang Yang Jianrong Cao School of Automation and Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070GansuChina China Railway Rolling Stock Corporation Qingdao Sifang Rolling Stock Research Institute Co. LtdQingdao 266000ShandongChina

Aiming at the current problems of high failure rate and low diagnostic efficiency of railway point machines(RPMs)in the railway industry,a short-time method of fault diagnosis is *** the effect of noise on power signals in the data acquisition process of the railway centralized signaling monitoring(CSM)system,this study utilizes wavelet threshold denoising to eliminate *** results show that the accuracy of fault diagnosis can be improved by 4.4% after denoising the power *** in order to attain a lighter weight and shorten the running time of the diagnosis model,Mallat wavelet decomposition and artificial immune algorithm are applied to RPM fault ***,voluminous experiments using veritable power signals collected from CSM are introduced,which show that combining these methods can procure higher precision of RPMs and curtail fault diagnosis *** substantiates the validity and feasibility of the presented approach.

关键词： railway point machines wavelet threshold denoising Mallat wavelet decomposition artificial immune algorithm

Study on risk assessment and factors ranking of the LTE-M communication system

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Transportation Safety and Environment 2023年第4期5卷 45-57页

作者： xiaochun wu Yu Gao Weichao Zheng School of Automation Electrical Engineering Lanzhou Jiaotong UniversityAnning West RoadLanzhou 730070GansuChina Communication Center Tianjin Rail Transit Operation Group Co.LtdNo.36Xuefu Industrial ParkTianjin 300000China

To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are *** to the features of LTE-M system,the risk evaluation system is *** enhanced structural entropy weight method is used to obtain the ***,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence ***,the system risk grade assessment result is *** the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is *** operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and *** results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is *** influencing indicator with the highest importance is the'equipment failure rate".

关键词： long-term evolution for the metro(LTE-M)system operational safety risk assessment improved evidence theory multi-attribute ideal reality comparative analysis(MAIRCA)method

Network View and Cognitive Mechanism for Virtual Network Resource Management Based Intelligent

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Chinese Journal of Electronics 2014年第3期23卷 574-578页

作者： wu xiaochun wu Chunming WANG Bin QIAN Yaguan LAN Julong Computer Science College Zhejiang University Institute of Network and Communication Engineering Zhejiang Gongshang University National Digital Switching System Engineering & Technology R&D Center

Network virtualization has been a particularly important driving force behind the development of NGN. Finding effective ways to control self-adapting virtual networks has become a research hot spot. This paper tries to find an efficient way in combining dynamic resource sensing with traffic character and requirements in virtual network, based on that an intelligent cognition based virtual network resources management model has been put forward. We design a network topology view by coloring network topology matrix with current resources model. We present an intelligent virtual resource management mechanism based on the proposed network topology view. Experiment results illustrate that the proposed mechanism can improve VN capacity by automatic resource adjustment, which can obtain high utilization of VN resources without increasing computational expenses.

关键词： Intelligent cognition Self-adapting Virtual network

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数字技术对创业机会识别的影响研究

创新与创业教育 2024年第2期15卷 9-19页

作者：吴小春陈建平张之剑武汉理工大学创业学院湖北武汉430070

数字化背景下,数字技术对创业活动产生了重要影响,这种影响体现在创业过程中的不同阶段。创业机会识别是创业过程的关键阶段,为探究数字技术赋能创业机会识别的作用机理,基于创业学习理论,构建了“数字技术—双元创业学习—创业机会识... 详细信息

数字化背景下,数字技术对创业活动产生了重要影响,这种影响体现在创业过程中的不同阶段。创业机会识别是创业过程的关键阶段,为探究数字技术赋能创业机会识别的作用机理,基于创业学习理论,构建了“数字技术—双元创业学习—创业机会识别”的理论模型。以新创企业为研究对象,通过调研得到223份有效问卷数据,采用层次回归分析法验证研究假设,结果表明:数字技术对双元创业学习(探索式学习、利用式学习)和创业机会识别均具有显著的正向作用;两个维度的创业学习在数字技术与创业机会识别之间均起到部分中介作用。研究结论有助于拓展数字技术和创业机会识别相关主题的理论研究,进一步丰富创业机会识别影响因素方面的研究成果,为数字化背景下的创业主体进行创业机会识别实践提供了理论参考。

关键词：数字技术探索式学习利用式学习创业机会识别

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Minimizing the effect of near-distance dielectric sensitivity on retrieving average aspect ratio of gold nanorod by optical extinction spectroscopy:in the case of CTAB adsorption

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Chinese Science Bulletin 2014年第16期59卷 1822-1831页

作者： Zhijian Hu Yinglu Ji Shuai Hou xiaochun wu CAS Key Laboratory of Standardization and Measurement for Nanotechnology National Center for Nanoscience and Technology

The aspect ratio(AR)is one of the most intriguing parameters of gold nanorods(GNRs),which plays an important role in determining localized surface plasmon(LSPR)*** of conventional imaging techniques,the optical extinction spectroscopy(OES)method has been developed for allowing fast statistically measuring the average AR under static *** this work,combining with the previous achievements in spectroscopic technique,we further analyze the effects of gold dielectric function and near distance dielectric *** former may reflect possible dielectric loss of real Au samples from ideal single *** latter reflects the cetyltrimethylammonium bromide(CTAB)adsorption on the surface of GNR induces different LSPR shifts below and above critical micelle concentration(CMC).However,their effect on the determination of AR has not been evaluated in OES *** average AR measurements as a function of absorbance of CTAB-GNRs and LSPR maximum below the CMC were *** results indicate that after considering these factors,the mean ARs obtained from spectroscopic techniques are closer to those obtained from imaging techniques.

关键词： CTAB 消光光谱吸附作用平均值纵横比纳米棒灵敏度近距离

铜对4Cr16Mo塑料模具钢切削性能的影响

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上海金属 2024年第2期46卷 57-63,70页

作者：刘友通李佳媛吴晓春上海大学材料科学与工程学院上海200444 上海大学省部共建高品质特殊钢冶金与制备国家重点实验室上海200444 上大鑫仑材料科技(广东)有限公司广东肇庆526105

将4Cr16MoCu、4Cr16Mo和SDP136钢在1030℃保温4 h,冷却至室温后回火两次,第一次为540℃×4 h,4Cr16MoCu钢的第二次回火工艺为590℃×3 h,4Cr16Mo和SDP136钢为565℃×3 h,使其硬度达到35~36 HRC。采用扫描电子显微镜检测钢的显微组织,采... 详细信息

将4Cr16MoCu、4Cr16Mo和SDP136钢在1030℃保温4 h,冷却至室温后回火两次,第一次为540℃×4 h,4Cr16MoCu钢的第二次回火工艺为590℃×3 h,4Cr16Mo和SDP136钢为565℃×3 h,使其硬度达到35~36 HRC。采用扫描电子显微镜检测钢的显微组织,采用数控车床进行切削性能试验。分别采用SY-3F型应变式三维测力传感器、红外测温仪、TR200粗糙度测量仪和超景深显微镜测定切削力、刀尖温度、工件粗糙度和磨损刀具的形貌。结果表明:在相同的切削条件下,铜的添加能延长刀具的使用寿命;切削4Cr16MoCu钢的刀具温度比切削4Cr16Mo钢的刀具温度低50℃,切削试验的前、中期4Cr16Mo钢的切削力比4Cr16MoCu钢大43~94 N,但后期4Cr16MoCu钢的切削力上升至839 N,比SDP136钢大211 N。

关键词：切削性能切削力磨损塑料模具钢