Contextual cues aid recovery from interruption: The role of associative activation.

A series of experiments introduced interruptions to the execution phase of simple Tower of London problems and found that the opportunity for preparation before the break in task reduced the time cost at resumption. Retrieval of the suspended goal was facilitated when participants were given the opportunity to encode retrieval cues during an "interruption lag" (the brief time before engaging in the interrupting task) but was impeded when these visual cues were subsequently altered following interruption. The results provide useful support for the goal-activation model (E. M. Altmann & G. J. Trafton, 2002), which assumes that context--at the points of both goal suspension and goal retrieval--is critical to efficient interruption recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Java异常处理

异常处理是Java程序设计中一个非常重要的机制,也是程序设计的一大难点,就异常和异常处理方式等方面进行介绍,并通过一个实例来验证异常。     

基于串空间认证测试的DTLS协议认证性分析

网络通信的普及和发展使得对网络协议尤其是安全协议的需求日益增长,同时安全要求及攻击方式的多样化对网络安全协议的效率和准确性提出了更高的要求。通过对各种协议安全性分析方法进行研究,采用串空间方法对DTLS协议进行形式化建模,进而采用认证测试方法进行协议认证性证明,用简明清晰的方式验证DTLS协议的认证性,保障了数据传输的安全。     

基于Windows异常处理机制研究

首先从系统层面和编译层面分析了Windows和C+KG-*3+异常处理的基本原理,指出了基于Windows的C+KG-*3+异常处理机制在使用过程中可能出现的逻辑错误,以及Windows运行时库中个别函数可能存在的此类安全隐患。为了更好地保证C+KG-*3+代码安全性和健壮性,综合上述研究提出了审计C+KG-*3+异常处理的方法和建议。     

基于CPN的工作流异常处理模型设计

工作流异常处理是工作流管理系统中的重要组成部分,但是它的实现既复杂又耗时。为了支持面向服务的工作流,层次化地描述异常处理,提出一种基于CPN的异常处理模型。在形式化描述工作流异常的基础上,采用补偿法作为异常处理方式,详细描述了处理结构中的异常监控、异常分析和补偿案例执行三个子过程。结合茶餐厅的运营模型的仿真实验证明了该模型可有效地分离工作流的异常处理逻辑和运行逻辑,并支持工作流管理系统的实施。     

Effect of growth-interrupted method on quality of AlGaAs/GaAs multiple quantum wells prepared by MBE

AlGaAs/GaAs multi-quantum well （MQW） was prepared by molecular beam epitaxy（MBE） with growth-interrupted heterointerface （GIH） method and continuous growth （CG） method, respectively. The microstructures Of the MQWs were characterized by double-crystal X-ray rocking curve （DCRC） and atomic force microscopy （AFM）, and the photoluminescence （PL） properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendelloesung fiinges are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum （FWHM） of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atomsfor a few minutes grower interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.     

水闸闸门开度显示异常故障的分析与排除

闸门控制系统故障将影响着水闸的正常运行,进而影响水闸工程效益的发挥,文章提出了闸门运行时导致闸门开度显示异常故障的原因是多样的,触摸屏、电路传输、编码器、传感器或机械传动装置任一方面出现问题都有可能导致此类故障的发生,通过分析排查确认此次问题出在机械传动装置方面,更换或修复相应的机械传动装置后排除了故障,同时分析了防止此类故障发生的有利条件或者排除此类故障的一般思路方法,确保水闸正常运行,发挥工程效益。     

浮点数学函数异常处理方法

异常会造成程序错误,实现完全没有异常的浮点计算软件也很艰难,因此,实现有效的异常处理方法很重要.但现有的异常处理并不针对浮点运算,并且研究重点都集中在整数溢出错误上,而浮点类型运算降低了整数溢出存在的可能.针对上述现象,面向基于汇编实现的数学函数,提出了一种针对浮点运算的分段式异常处理方法.通过将异常类型映射为64位浮点数,以核心运算为中心,将异常处理过程分为3个阶段:输入参数检测(处理INV异常)、特定代码检测(处理DZE异常和INF异常)以及输出结果检测(处理FPF异常和DNO异常),并从数学运算的角度对该方法采用分段式处理的原因进行了证明.实验将该方法应用于Mlib浮点函数库,对库中600多个面向不同平台的浮点函数进行了测试.测试结果表明:该方法能够将出现浮点异常即中断的函数个数从90%降到0%.同时,实验结果验证了该方法的高效性.     

Performance analysis of a non-preemptive priority queuing system subjected to a correlated Markovian interruption process

In this paper, we consider a discrete-time queuing system with head-of-line non-preemptive priority scheduling and a single server subjected to server interruptions. We model the server interruptions by a correlated Markovian on/off process with geometrically distributed on and off periods. Two classes of traffic are considered, namely high-priority and low-priority traffic. In the first part of the paper, we derive an expression for the functional equation describing the transient evolution of this priority queuing system. This functional equation is then manipulated and transformed into a mathematical tractable form. This allows us to derive the joint probability generating function (pgf) of the system contents. From this pgf, closed-form expressions for various performance measures, such as mean and variance of system contents and customer delay can be derived. Finally, we illustrate our solution technique with some numerical examples, whereby we demonstrate the negative effect of correlation in the interruption process on the performance of both classes. Some numerical results illustrating the impact of second-order characteristics of the arrival process on mean delays are also presented. The proposed approach which is purely based on pgfs is entirely analytical and enables the derivation of not only steady-state but transient performance measures, as well. The paper presents new insights into the performance analysis of discrete-time queues with service interruption and it also covers some previously published results as a special case.

Scope and purpose

In this contribution, we consider a practical queuing model, with HOL priority scheduling, two classes of traffic, and a server which is subjected to a correlated Markovian interruption process. We first derive a non-linear functional equation relating the joint pgf of the system state vector between two consecutive slots. Then we outline a solution technique to solve for this functional equation. This allows us to derive the joint pgf of the system contents of both classes, from which various performance measures related to mean system contents and customer delays are derived. We also demonstrate how the proposed approach allows for derivation of transient performance measures, as well. It should be noted that detailed coverage of the transient analysis of the system is beyond the scope of this paper.To our best knowledge, this is the first initiative that aims to explore the performance of queuing systems with priority scheduling when the shared server is subjected to service interruption. The paper also generalizes the results of Walraevens et al. (Analysis of a single-server ATM queue with priority scheduling, Computers & Operations Research 2003;30(12):1807–30) by incorporating service interruption into their original queuing model. By means of numerical results, the paper also demonstrates the effect of correlation in the service interruption process on the performance of both classes of customers. The impact of second-order characteristics of the arrival process on mean delays is also investigated.     

Triage Drift: A Workplace Study in a Pediatric Emergency Department

This paper presents a workplace study of triage work practices within an emergency department (ED). We examine the practices, procedures, and organization in which ED staff uses tools and technologies when coordinating the essential activity of assessing and sorting patients arriving at the ED. The paper provides in-depth empirical observations describing the situated work practices of triage work, and the complex collaborative nature of the triage process. We identify and conceptualize triage work practices as comprising patient trajectories, triage nurse activities, coordinative artefacts and exception handling; we also articulate how these four features of triage practices constitute and connect workflows, organize and re-organize time and space during the triage process. Finally we conceptualize these connections as an assessing and sorting mechanism in collaborative work. We argue that the complexities involved in this mechanism are a necessary asset of triage work, which calls for a reassessment of the concept of triage drift.