电镜的管理与维护

电镜在自然科学的各个领域以及为推进高等教育现代化科学化方面,已经成为不可缺少的技术设备。随着电镜技术的不断更新和发展,有许多科研成果都是通过电镜直接取得的。我国电镜的数量每年都有程度不同的增加,但总的来说并不是很多,尤其在边远地区和省份电镜数量就更少,甚至有些地区仅有几台。由于电镜价格昂贵,考虑到国家财力状况,尚不能大量购置,因此,电镜还不能作为常规仪器广为使用,为了进行科学研究和培养科技人才,目前我国电镜绝大部分都集中在科研机构和大专院校。如何用好现有电镜,使其充分发挥作用,关键在管理。认真负责的管好电镜谁都能作到,但要作到电镜在长期运转中不出问题或者少出问题,一切保持正常,即要顺利开展工作,又有保持整机性能的完好如     

JEM-1010型透射电镜计算机故障的检修

我所电镜室的JEM-1010型透射电子显微镜采用计算机控制系统,通过计算机可设定电镜的一些工作条件和设定照相底片记录文字,它还具有显示各工作点的数值、机内测量数值等功能,它令电镜的操作变得比较简便。在这台电镜几年的运转过程中,该计算机曾数次出现所谓“死机”的故障,电镜计算机“死机”的原因很多,现将我室电镜计算机因电器方面的故障而引起“死机”的情况介绍如下,供同行们参考。JEM-1010型透射电镜有一计算机操作显示屏,它显示电镜有关的各种数据、设定,当计算机出现“死机”时,则不能通过键盘输入指令(在显示屏上光标不移动),这…     

基于VB的电镜图片中粒径分布统计程序的开发

纳米材料粒径分布是材料合成、催化应用等领域一项重要的表征手段。在统计电镜图片粒径分布的方法中,目前主要以传统手动测量和全自动分析软件两种为主。传统手动测量存在费时、复杂等缺点,而全自动分析软件也很难有效地测试非球形、分布复杂的颗粒粒径。以Visual Basic 6.0作为编程平台,集合图片处理、数据统计、数据导出等技术,开发了一款电镜图片粒径分布统计程序。该程序支持结果快速查看和数据导出功能,为测量各种形貌的微/纳米材料的粒径提供了一种方便的方法。     

2012年全国电子显微学会议及征文通知（第一轮）

一、2012年全国电子显微学会议通知2012年全国电子显微学会议将在夏秋季举行。大会的学术交流内容包括透射电子显微镜、扫描电子显微镜、微束分析、扫描探针显微镜（包括STM、AFM等）、激光共聚焦显微镜等在物理学、材料科学、纳米科技、生命科学、化学化工、环境科学、地学等领域中的基础和应用研究成果；显微学相关仪器的理论、技术和实验方法的发展与改进；电镜及其它显微学仪器的使用、改进与维修经验的交流等。大会将邀请相关仪器设备的厂商做电镜和其他仪器的最新发展介绍及产品展示。     

2014年全国电子显微学会议及征文通知（第一轮）

一、2014年全国电子显微学会议通知 2014年全国电子显微学会议将于10月中旬择地举行。大会的学术交流内容包括透射电子显微镜、扫描电子显微镜、微束分析、扫描探针显微镜（包括STM、AFM等）、激光共聚焦显微镜等在物理学、材料科学、纳米科技、生命科学、化学化工、环境科学、地学等领域中的基础和应用研究成果;显微学相关仪器的理论、技术和实验方法的发展与改进;电镜及其它显微学仪器的使用、改进与维修经验的交流等。大会将邀请相关仪器设备的厂商做电镜和其他仪器的最新发展介绍及产品展示。     

2014年全国电子显微学会议及征文通知（第一轮）

一、2014年全国电子显微学会议通知2014年全国电子显微学会议将于10月中旬择地举行。大会的学术交流内容包括透射电子显微镜、扫描电子显微镜、微束分析、扫描探针显微镜（包括STM、AFM等）、激光共聚焦显微镜等在物理学、材料科学、纳米科技、生命科学、化学化工、环境科学、地学等领域中的基础和应用研究成果；显微学相关仪器的理论、技术和实验方法的发展与改进；电镜及其它显微学仪器的使用、改进与维修经验的交流等。大会将邀请相关仪器设备的厂商做电镜和其他仪器的最新发展介绍及产品展示。     

2013年全国电子显微学会议及征文通知(第一轮)

一、2013年全国电子显微学会议通知2013年全国电子显微学会议将于10月中旬在重庆市举行。大会的学术交流内容包括透射电子显微镜、扫描电子显微镜、微束分析、扫描探针显微镜(包括STM、AFM等)、激光共聚焦显微镜等在物理学、材料科学、纳米科技、生命科学、化学化工、环境科学、地学等领域中的基础和应用研究成果;显微学相关仪器的理论、技术和实验方法的发展与改进;电镜及其它显微学仪器的使用、改进与维修经验的交流等。大会将邀请相关仪器设备的厂商做电镜和其他仪器的最新发展介绍及产品展示。     

电镜在肾小球疾病诊断中的应用

电镜检查在肾活检诊断中具有重要的作用，与常规组织学观察，免疫组化检查一起构成了各种肾小球疾病诊断的基础。我们自１９８０年以来已接收肾活检电镜标本３５００余例，在肾脏病的治疗和研究中发挥了重要的作用。本文对如何做好肾活检的电镜诊断，肾小球的超微结构和基本病变，电镜在肾小球疾病中的诊断作用以及免疫电镜在肾小球疾病研究及诊断中的价值等进行了介绍和讨论。     

2015年全国电子显微学会议及征文通知(第一轮)

一、2015年全国电子显微学会议通知2015年全国电子显微学会议将于10月13-18日在成都举行。大会的学术交流内容包括透射电子显微镜、扫描电子显微镜、微束分析、扫描探针显微镜(包括STM、AFM等)等在物理学、材料科学、纳米科技、生命科学、化学化工、环境科学、地学等领域中的基础和应用研究成果;显微学相关仪器的理论、技术和实验方法的发展与改进;电镜及其它显微学仪器的使用、改进与维修经     

JEM-1200EX电镜底片数据显示的调整

日本电子公司的ＪＥＭ１２００ＥＸ电镜在拍摄电镜照片时,通过一个底片数据显示ＣＲＴ,可以将放大倍数、加速电压、显微标尺等数据及一行１２个字符的注释内容打印到底片的一个注释框中记录下来,这一功能为底片的保存提供了很大的方便。通常底片注释框在电镜安装时已由厂方安装人员调整好,用户在使用时不必再对其进行调整。但是如果用户在下述特殊情况发生时,就需要对底片注释框进行重新设定。①用户更换了所使用的电镜底片的生产厂家时。不同厂家生产的电镜胶片,在感光性能上往往存在着较大的差别,因此在更换了不同厂家生产的底片…     

虚拟现实技术在电子显微镜操作模拟中的应用

基于虚拟现实技术对电子显微镜外观结构及其操作流程进行虚拟动态仿真。首先运用三维建模软件对电子显微镜进行精细建模,并对其中涉及到的关键问题,如模型优化、材质制作等进行了阐述。在此基础上,研究运用虚拟现实引擎对电子显微镜的操作流程模拟进行了设计与实现。采用这种的模拟系统,用户可以在虚拟环境下直观、交互地了解电子显微镜的复杂结构,并体验电子显微镜的操作流程。该项工作对电子显微镜的三维动态展示、使用流程演示、用户体验式培训都具有很好的应用意义。文章给出了实例和可视化结果。     

A model for channel sharing in land mobile radio dispatch services

A modeling approach to the problem of channel sharing in land mobile radio dispatch services, which is based on real life traffic data, is presented. In order to apply the GI/G/1 queueing model, the first step consists in identifying a message arrival process for each user by means of observed available data. It is then shown how to use simple approximation formulas to evaluate the expected waiting time, when two or more independent users must share a common channel. GPSS simulations were performed to verify that the proposed approach is suitable to practical applications.     

基于对称KL距离的用户行为时序聚类方法

网络用户随时间变化的行为分析是近年来用户行为分析的热点,通常为了发现用户行为的特征需要对用户做聚类处理。针对用户时序数据的聚类问题,现有研究方法存在计算性能差,距离度量不准确的缺点,无法处理大规模数据。为了解决上述问题,该文提出基于对称KL距离的用户行为时序聚类方法。首先将时序数据转化为概率模型,从划分聚类的角度出发,在距离度量中引入KL距离,用以衡量不同用户间的时间分布差异。针对实网数据中数据规模大的特点,该方法在聚类的各个环节针对KL距离的特点做了优化,并证明了一种高效率的聚类质心求解办法。实验结果证明,该算法相比采用欧式距离和DTW距离度量的聚类算法能提高4%的准确度,与采用medoids聚类质心的聚类算法相比计算时间少了一个量级。采用该算法对实网环境中获取的用户流量数据处理证明了该算法拥有可行的应用价值。     

Wireless channel allocation using an auction algorithm

We develop a novel auction-based algorithm to allow users to fairly compete for a wireless fading channel. We use the second-price auction mechanism whereby user bids for the channel, during each time slot, based on the fade state of the channel, and the user that makes the highest bid wins use of the channel by paying the second highest bid. Under the assumption that each user has a limited budget for bidding, we show the existence of a Nash equilibrium strategy, and the Nash equilibrium leads to a unique allocation for certain channel state distribution, such as the exponential distribution and the uniform distribution over [0, 1]. For uniformly distributed channel state, we establish that the aggregate throughput received by the users using the Nash equilibrium strategy is at least 3/4 of what can be obtained using an optimal centralized allocation that does not take fairness into account. We also show that the Nash equilibrium strategy leads to an allocation that is Pareto optimal (i.e., it is impossible to make some users better off without making some other users worse off). Based on the Nash equilibrium strategies of the second-price auction with money constraint, we further propose a centralized opportunistic scheduler that does not suffer the shortcomings associated with the proportional fair scheduler.     

太赫兹自由电子激光放大器研究

太赫兹自由电子激光(FEL)是获得高功率太赫兹辐射的重要途径,目前运行的太赫兹FEL装置基本上都采用振荡器结构,若采用FEL放大器模式,则可产生具有更高峰值功率的太赫兹辐射。本文以北京大学超导电子直线加速器的束流参数为基础,通过模拟分析确定了太赫兹FEL放大器对太赫兹种子源、电子束流及波荡器等的要求。模拟结果显示,太赫兹种子的峰值功率在10 W以上即可实现太赫兹FEL放大;在较易实现的参数条件下,可获得峰值功率数兆瓦的太赫兹辐射。     

透射电镜电子染色方法的改良

为提高透射电镜生物样品超薄切片的染色效率,在传统染色方法基础上进行改良,使用自制染色装置,在较短时间内完成大批生物样品超薄切片的电子染色。与传统方法相比较省时省药,减少污染机率,电镜观察的超微结构清晰,反差较好。     

太赫兹自由电子激光放大器研究

太赫兹自由电子激光(FEL)是获得高功率太赫兹辐射的重要途径,目前运行的太赫兹FEL装置基本上都采用振荡器结构,若采用FEL放大器模式,则可产生具有更高峰值功率的太赫兹辐射。本文以北京大学超导电子直线加速器的束流参数为基础,通过模拟分析确定了太赫兹FEL放大器对太赫兹种子源、电子束流及波荡器等的要求。模拟结果显示,太赫兹种子的峰值功率在10 W以上即可实现太赫兹FEL放大;在较易实现的参数条件下,可获得峰值功率数兆瓦的太赫兹辐射。     

User’s behavior study for smart houses occupant prediction

This paper deals with the smart house occupant prediction issue based on daily life activities. Based on data provided by nonintrusive sensors and devices, our approach use supervised learning technics to predict the house occupant. We applied support vector machines classifier to build a behavior classification model and learn the users’ habits when they perform activities for predicting and identifying the house occupant among a group of inhabitants. We analyzed the publicly available dataset from the Washington State University smart apartment tesbed. We particulary studied the grooming, having breakfast and bed to toilet activities. The results showed a hight prediction precision and demonstrated that each user has his own manner to perform his daily activities and can be easily identified by just learning his habit.     

User Independent Paging Scheme for Mobile IP

Multi-step paging has been widely proposed in personal communications services (PCS) systems to reduce the signaling overheads. Similar ideas can be applied to Mobile IP to provide IP paging services. However, current proposed multi-step paging schemes are user dependent under which the partition of paging areas and the selection of paging sequence are different for each user. The performance of a user dependent paging scheme for individual users may be affected by many factors. It is often difficult to achieve perfect performance for each user. In addition, when multiple users are paged at the same time, user dependent paging schemes may consume significant system resources. This paper introduces a user independent paging scheme where the paging criterion is not based on individual user information. The goal of user independent paging is to provide satisfactory overall performance of the whole system, when personalized optimal performance for each user is hard to obtain. The user independent paging scheme is proposed for IP mobility for its easy implementation and convenient combination with paging request aggregation. The paging criterion adopted is the mobility rate of each subnet determined by the aggregated movements of all mobile users. In order to implement the proposed scheme, a concept of “semi-idle state” is introduced and the detailed solution for obtaining mobility rate is presented. Analytical results show that when paging one user at a time, the performance of the proposed user independent paging scheme is comparable to that of the paging schemes based on perfect knowledge of user movement statistics. When paging multiple users simultaneously and when the knowledge on individual user behavior is not perfectly accurate, the proposed scheme has remarkable advantages in terms of reducing the overall paging cost. Jiang Xie received her B.E. degree from Tsinghua University, Beijing, China, in 1997, M.Phil. degree from Hong Kong University of Science and Technology in 1999, and M.S. and Ph.D. degrees from Georgia Institute of Technology in 2002 and 2004, respectively, all in electrical engineering. She is currently an assistant professor with the Department of Electrical and Computer Engineering at the University of North Carolina-Charlotte. Her current research interests include resource and mobility management of wireless networks,QoS provisioning, and next-generation Internet. She is a member of IEEE and ACM.     

Understanding user privacy expectations: A software developer’s perspective

Software developers are trained to develop and design software applications that provide services to users. However, software applications sometimes collect users’ data without their knowledge. When applications collect and use users’ data without transparency, this leads to user privacy invasions because users do not expect the application to collect and use these information. Therefore, it is important that software developers understand users’ privacy expectations when designing applications in order to handle user data transparently in software applications. However, due to the lack of systematic approaches to extract user privacy requirements, developers end up designing applications either based on their assumptions on user privacy expectations, or relating to their own expectations of privacy as a user. Nevertheless, how accurate these perceived privacy expectations are against actual user expectations is not currently known. This research focuses on investigating developers’ privacy expectations from a user point of view against users’ privacy expectations. We also investigate developers’ assumptions on user privacy expectations against actual user privacy expectations. Our findings revealed that developers’ assumptions on user privacy expectations are close to their own expectations of privacy from a user point of view and that developers’ privacy expectations from a user point of view are significantly different from actual user privacy expectations. With this understanding, we provide recommendations for software developers to understand and acknowledge user expectations on privacy when they design and develop applications.