计算机病毒及其防治的探讨

本文阐述了计算机病毒的概念,对计算机病毒进行了分类,同时分析了各类病毒的特点。并着重介绍了对病毒的防范措施以及清除的方法。     

量子线中施主杂质的光致电离截面

本文就几种不同的线宽计算了准一维GaAs量子线中施主杂质的光致电离截面,同时也研究了磁场对光谱的影响。     

离子电子法配平方程式的简便方法

本文介绍了离子电子法在配平半反应时,利用离子、电子及溶液的介质,来调节反应式两边的电荷数,使之相等.     

多方发挥物理实验教学的职能作用

当前我国医学教育中物理实验教学存在弱点:对物理教育不重视,实验条件差,仪器、设备陈旧,实验选项过时,实验课时少.针对存在的问题及现状,在现有的条件之内,我们提出了物理实验课的改进措施:认真做好实验准备,发挥教师的主导作用,督查学生亲自动手,利用现有仪器设备,不断改善实验条件,重视教学情况的反馈信息.     

高精度低速数据采集系统

本文为Applel Ⅱ微型计算机提供了一种廉价的高精度低速数据采集系统。该系统的采样频率为3Hz,精度为1/20000,并拥有8个模拟输入通道,适用于仪表自动记录等低速环境。     

On a Class of Nonlinear AR(P) Models with Nonlinear ARCH Errors

This paper studies general sufficient conditions for the geometric ergodicity and the existence of moments for a class of nonlinear autoregressive models with nonlinear ARCH errors. Applications of these conditions to various well-known nonlinear time series models yield specific sufficient conditions, many of which are new or generalizations of existing conditions.     

A modified likelihood ratio test for homogeneity in finite mixture models

Testing for homogeneity in finite mixture models has been investigated by many researchers. The asymptotic null distribution of the likelihood ratio test (LRT) is very complex and difficult to use in practice. We propose a modified LRT for homogeneity in finite mixture models with a general parametric kernel distribution family. The modified LRT has a χ-type of null limiting distribution and is asymptotically most powerful under local alternatives. Simulations show that it performs better than competing tests. They also reveal that the limiting distribution with some adjustment can satisfactorily approximate the quantiles of the test statistic, even for moderate sample sizes.     

INNOVACQ: Serials control at Boalt Hall

Many changes in the Law School Library have occurred during this past year because of INNOVACQ. Within the Serials/Acquisitions Section, almost all the routines and procedures have been radically redefined to allow for the computerization of serials control. There have been some staff reassignments and shifts in responsibility, and in most instances, old tasks and manual file maintenance have been done away with completely and replaced by work at a VDT. Naturally, the impact of INNOVACQ has also been felt in the Cataloging Section, and the instant availability of serials check-in and routing information in public services has certainly added a level of service that was never possible before. In addition, the immediate and up-to-date fiscal information has been a boon for both the library's collection development officers and the Library administration.Various staff members throughout the year have been working to clean up and upgrade different parts of the serials files and to add or exchange better information in a number of fields in each record. Past payment history has been keyed into over 2/3 of the records in the file. The records for all the loose-leaf services contracted for by the Library are not fully online.All the records for our California documents have been edited and check-in cards have been created for this large and obviously important part of the file. Conversion of the U.S. documents which had been deferred at the very beginning of the fiscal year, has begun and most entries now can be checked-in and claimed online.All invoices (both serials and monographs) for this fiscal year have been processed on INNOVACQ, and while there are still some vendor and fund anomalies, Boalt has better, more comprehensive — and certainly more accurate — financial records than ever before.A massive editing and claiming project has recently gotten under way. All titles on INNOVACQ are being checked against the shelf list to make sure that all the bibliographic elements in each record are in sync and are presented in a standard, retrievable (punctuation and spacing count in INNOVACQ) format. Routine claiming (as part of serials check-in) has been in place for some time now, and that activity was begun when that feature was delivered. A second part of the editing project, is however, to get the thousands of blank boxes out of the check-in screens where they will remain as claimable items until some sort of purging action is taken. The files are now being gone through (a simple command in INNOVACQ can allow one to review every check-in record in the system), our holdings are being checked on the shelves, and decisions to claim or replace the missing pieces are being made. We anticipate that this editing/ claiming project will take approximately half a year.The INNOVACQ system was pretty exciting when we first saw it demonstrated, and we were eager then to incorporate it into our technical processing activities here at Boalt. If anything, our enthusiasm has grown as the capabilities of INNOVACQ have been realized. Enhancement and refinement — some at our prompting, others by the design staff at Innovative Interfaces — over the past year have resulted in what we believe to be the most comprehensive and easy-to-use serials control system available. Our confidence was manifested when we shifted all of our acquisitions activities from RLIN to INNOVAQ at the beginning of our fiscal year in mid-1984.Many tasks remain for the Law Library in making the best use of the INNOVACQ system. The rapid acceptance by the public service staff and users has been heartening, and the continuing work to clean up the Serials Records has proven fruitful. System performance and maintenance have been outstanding, and we are excited about various possibilities for future growth. It has not been a simple nor uncomplicated process, but the gains realized by the Law library have been substantial.     

A Markov regime‐switching model for crude‐oil markets: Comparison of composite likelihood and full likelihood

We use the two‐state Markov regime‐switching model to explain the behaviour of the WTI crude‐oil spot prices from January 1986 to February 2012. We investigated the use of methods based on the composite likelihood and the full likelihood. We found that the composite‐likelihood approach can better capture the general structural changes in world oil prices. The two‐state Markov regime‐switching model based on the composite‐likelihood approach closely depicts the cycles of the two postulated states: fall and rise. These two states persist for on average 8 and 15 months, which matches the observed cycles during the period. According to the fitted model, drops in oil prices are more volatile than rises. We believe that this information can be useful for financial officers working in related areas. The model based on the full‐likelihood approach was less satisfactory. We attribute its failure to the fact that the two‐state Markov regime‐switching model is too rigid and overly simplistic. In comparison, the composite likelihood requires only that the model correctly specifies the joint distribution of two adjacent price changes. Thus, model violations in other areas do not invalidate the results. The Canadian Journal of Statistics 41: 353–367; 2013 © 2013 Statistical Society of Canada