基于PEPA的云计算资源分配算法性能评价

资源分配是云计算的核心之一,对云计算资源分配算法的性能进行评价可为云计算平台设计提供指导.讨论了两种云计算资源分配算法,提出了一种基于PEPA的资源分配算法的性能评价模型,该模型通过建立云计算系统中各组件之间的交互关系进行形式化分析和推理,获得了云计算系统性能的评价指标.实验通过分析资源分配过程中不同参数变化对系统性能的影响,结果表明,PEPA模型方法可以直接评估资源分配算法性能的优劣,并能够确定算法性能提升的关键因素,从而减少云平台设计过程的周期.     

进程代数在性能评价中的应用研究

介绍了使用随机进程代数作为性能建模的一种方法,着重介绍了Hillston提出的性能评价进程代数(PEPA),主要论述了使用PEPA模型性能评价方法及特点,讨论资源利用率系统性能分析方法,最后归纳了性能评价进程代数(PEPA)研究的应用领域,并对未来研究方向提出了展望.     

笼状磷酸酯PEPA的合成工艺研究

在以二氧六环为溶剂,季戊四醇与三氯氧磷物料比为1∶1,缓慢滴加三氯氧磷的条件下,合成阻燃剂中间体双环笼状磷酸酯1-氧基磷杂-4-羟甲基-2,6,7-三氧杂双环[2.2.2]辛烷(PEPA),并对影响其产率的几个主要因素,如:反应温度、反应时间及是否进行预处理以及是否添加缚酸剂等因素进行初步研究,优化工艺路线。     

硼酸锌对MPP/PEPA阻燃PP性能的影响

采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的无卤阻燃PP。研究了MPP/PEPA质量比和硼酸锌(ZB)用量对PP阻燃和力学性能的影响。结果表明:MPP/PEPA质量比为3∶2时,复配效果最好;添加少量的ZB即可显著提高材料的阻燃性能;当MPP/PEPA/ZB添加量分别为12%、8%和2%时,阻燃PP的氧指数高达35%,并具有较好的力学性能。TGA结果表明:添加ZB可以起催化MPP/PEPA酯化,促进成炭的作用;SEM分析表明,ZB可以起到稳定炭层,增加炭层厚度的作用。     

4A分子筛对PP/MPP/PEPA膨胀阻燃体系的协同作用

以4A分子筛为阻燃协效剂,采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的无卤阻燃PP。研究了4A分子筛用量对PP阻燃性能和协同作用的影响。结果表明:添加少量的4A分子筛即可显著提高PP的阻燃性能;当MPP/PEPA/4A分子筛添加量分别为12%、8%和2%时,阻燃PP的氧指数高达33。TGA、FTIR分析和体视显微镜及SEM观测结果表明:添加少量的4A分子筛可以催化MPP/PEPA间的酯化反应,促进体系成炭,形成更致密的炭层,从而提高材料的阻燃性能。     

Dynamic Scheduling Policy for Patient Flow in a Smart Environment

Given the popularity of smart environment in a hospital involving the participation of a large group of patients, scheduling of patients towards their desired des-tination is still being a challenging issue. With the devel-opment of Internet of Things (IoT), smart environments are increasingly being deployed in various public scenar-ios and in particular, hospitals are an important target environment for smart environments. This paper models a dynamic scheduling policy based on a patient flow sce-nario in order to solve the queuing issue and facilitate peo-ple's experience. The dynamic scheduling policy aims to forward incoming patients to dissolve jams especially at the peaks by giving accurate predication of appointment time. The main modelling technique is a formal method— Performance evaluation process algebra (PEPA). The findings show that the dynamic scheduling policy is able to efficiently improve the patient flow.     

Performance Modeling and Evaluation for Optical Access Networks

GEPON （gigabit Ethemet passive optical network） is widely deployed to realize the economical FTTH （fiber-to-the home） system for supporting high speed Internet and video distribution service. Looking ahead, next home FTTH standardization activities, 10G-EPON, were completed at the IEEE 802.3av Task Force in 2009, and the standards had specified the co-existence of 10G-EPON on the same exist optical access distribution network as a cost-effective solution. A key device in such a system is an optical receiver IC （integrated circuit） with a quick response and high sensitivity that realizes high efficiency in data transmission. This paper also reports burst-mode optical receiver ICs fabricated using 0.25 ktm SiGe BiCMOS （Silicon-germanium Bipolar Complementary Metal Oxide Semiconductor） technologies for a 10G-EPON system, which is a promising access network for a next generation PON system. The results show that SiGe BiCMOS can provide high performance and cost effective receiver ICs for 10G-class PON systems. The authors use PEPA （performance evaluation process algebra） to evaluate a typical PON system＇s performance. The approach is more convenient, flexible and lower cost than the former simulation method which needs to develop special hardware and software tools. Moreover, they can easily analyze how changes in performance depend on changes in a particular mode by supplying ranges for parameter values.     

阻燃成炭剂二甲基硅氧基双笼环磷酸酯的合成

1-氧基磷杂-4-羟甲基-2,6,7-三氧杂双环[2.2.2]辛烷(PEPA)与二甲基二氯硅烷反应合成阻燃成炭剂——二甲基硅氧基双笼环磷酸酯,即二甲基硅酸二{1-氧基磷杂-2,6,7-三氧杂双环[2.2.2]辛烷-(4)-甲}酯(DSDE)。考察了不同溶剂、反应温度和反应物配比对产物产率的影响,得到了最佳的反应条件是PEPA与二甲基二氯硅烷的摩尔比为2.16∶1,产率达92.6%。通过FTIR、1HNMR、元素分析、差热分析及极限氧指数表征了产物的结构及性能。研究表明,目标产物有较好的阻燃成炭性和热稳定性。     

PEPA阻燃环氧树脂的性能研究

将反应型含磷阻燃剂1-氧代-4-羟甲基-2,6,7-三氧杂-1-磷杂双环[2.2.2]辛烷(PEPA)与环氧树脂(EP)反应制得含磷EP,经固化剂间苯二胺固化后得到阻燃EP.表征了阻燃EP的热稳定性、成炭性和阻燃性能等.结果显示,PEPA的羟基与EP的环氧基团发生反应,使EP环氧当量提高.随着PEPA含量增加,阻燃EP的氧指数逐渐增大,起始分解温度降低,最终质量保持率增大.PEPA的加入对阻燃EP的玻璃化转变温度影响不大.燃烧后形成的炭层表面结构致密,内部多孔.     

Cr2O3增效阻燃PP的制备及其热降解性能的研究

以Cr2O3为阻燃协效剂,采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的无卤阻燃PP.研究了Cr2O3添加量对PP阻燃性能和协效作用的影响.结果表明:添加少量的Cr2O3可显著提高PP的阻燃性能.当MPP/PEPA/Cr2O3添加量分别为12%、8%和2%时,阻燃PP的氧指数高达31.5%.TGA、FTIR和Flynn-Wall法热降解活化能分析结果表明:添加Cr2O3可以起催化MPP/PEPA酯化,促进成炭的作用,使PP的活化能提高.