云计算环境下基于主动预测的节点部署模型研究

随着云计算的不断普及,越来越多的用户选择将自身的业务迁移至云计算系统。 用户的使用习惯与社会日常的运行规律 也伴随着大量用户涌入云计算系统,如每早8点集中地向云计算系统申请资源节点,这给系统带来了一种可预期的资源冲击。针对上述问题,提出了一种基于主动预测模式的资源部署模型。该模型首先根据预测模块中Holt-Winters季节指数平滑模型的算法周期长度来预测下一个时间周期的任务请求量,通过设计的主动预测算法判断是否应对当前的任务请求量做出响应并得出其具体数量、位置等参数指标,以实现对用户使用规律的主动应对。使用CloudSim进行仿真实验,系统地评判模型的性能。实验结果表明,AF-HW模型在应对可预测的海量并发任务请求时可有效地提升单点及整体的响应速率,使用户得到更好的体验。     

A predictive functional control algorithm for multivariable systems with time delay

To improve the dynamic characteristics and the coupling capability, a new predictive functional control algorithm is proposed for strong coupling multivariable systems with time delay, which combines predictive functional control and decoupliug control. First, a decoupling control algorithm is proposed, in which first-order models with time delay are established by analyzing the amplitude-frequency and phase-frequency characteristics of the decoupled subject. Then, a controller is designed for the single-variable subjects after decoupling based on the principles of predictive functional control. The simulation results show that this proposed algorithm has less online computation time and faster tracking. It can provide a more effective control for complex multivariable systems.     

多变量预测控制软件在加氢分馏装置控制中的应用

针对加氢分馏装置分馏塔工艺特点,重点分析加氢分馏塔所面临的控制问题,采用多变量预测控制软件APC—Adcon,通过实验测试、模型辨识、控制器和切换逻辑设计等工作实现该工业分馏塔系的多变量预测控制,显著提高两塔运行参数的平稳性,有效降低操作人员的操作难度。实际应用的结果表明该多变量预测控制系统可有效地克服干扰、确保工艺参数的平稳运行。通过该系统的应用使在相同的负荷下,燃料气减少5％,显著提高分馏塔的分离能力,组分切割更为合理,航空煤油收率提高0.4％,取得了显著的经济效益。     

以太网中双绞线超长布线的论证和实践

在IEEE802．3系列标准以太网的布线中,五类双绞线的长度限制在100米内,当距离超长时,会造成网络故障。为了解决这个问题,本文主要分析CSMA／CD和双绞线的性能,对超出传输长度的限制进行分析。最后还通过实测证明在一定环境距离内,超长使用廉价双绞线替代高成本光缆设备的可行性。     

IEEE802.15.4无线传感器网络仿真与性能评估

IEEE802.15.4标准是为满足低速率、低能耗、低成本需求而制定的无线个人区域网（LR_WPAN）规范。通过用网络仿真软件NS2对基于IEEE802.15.4的无线传感器网络的主要性能指标进行分析,较为详实地论述了IEEE802.15.4MAC层基于时槽的CSMA/CA机制,最后给出仿真环境及其结果,并进行度量分析和阐述各指标间的依赖关系。     

基于OPNET的CSMA/CD改进与仿真

以太网中采用CSMA/CD使得网络时延不确定和时变与时延的随机性导致控制品质的下降,为了改善以太网的延迟抖动性能,对以太网采用的TBEB算法进行改进,提出自适应退避算法,并用OPNET对改进的算法进行仿真分析.     

电磁骚扰自动测试系统中的寻优算法设计

针对电磁骚扰测试转台的特殊要求,根据PID调节器和最小拍控制超调量小,响应速度快,跟随性能强的特点,设计了一种转台的最优控制算法。仿真结果表明,应用此控制方法可以实现电磁骚扰测试转台系统响应速度快、超调量小、控制效果好及抗干扰能力强的优点。该方法具有一定的实用意义和经济价值。     

Predicting defect-prone software modules using support vector machines

Effective prediction of defect-prone software modules can enable software developers to focus quality assurance activities and allocate effort and resources more efficiently. Support vector machines (SVM) have been successfully applied for solving both classification and regression problems in many applications. This paper evaluates the capability of SVM in predicting defect-prone software modules and compares its prediction performance against eight statistical and machine learning models in the context of four NASA datasets. The results indicate that the prediction performance of SVM is generally better than, or at least, is competitive against the compared models.     

Min–Max MPC based on a network problem

In general, min–max model predictive controllers have a high computational burden. In this work, an efficient implementation of this class of controllers that can be applied to linear plants with additive uncertainties and quadratic cost functions is presented. The new approach relies on the equivalence of the maximization problem with a network problem. If a given condition is satisfied, the computational burden of the proposed implementation grows polynomially with the prediction horizon. In particular, the resulting optimization problem can be posed as a quadratic programming problem with a number of constraints and variables that grows in a quadratic manner with the prediction horizon. An alternative controller has been proposed for those systems that do not satisfy this condition. This alternative controller approximates the original one with a given bound on the error.     

无线传感器网络CSMA博弈优化算法研究

提出了一种通用的数学模型GO/CSMA(Game Optimization CSMA),用于优化CSMA退避机制.GO/CSMA以节点发包概率τ为优化变量,建立n人非合作混合策略博弈模型.以吞吐量和成功发包概率作为博弈效用函数为例,独立进行两个回合博弈,博弈的结果经过多约束单目标规划优化后得到折衷的τ~*,并据此设计出最小竞争窗口CWmin.仿真结果表明GO/CSMA显著提高了MAC层的传输效率.GO/CSMA可进一步扩展为对网络的其它多个性能(时延、丢包率、能耗、公平性)进行折衷的博弈优化.