青藏铁路GSM-R网络TCU重启故障原因分析与查找

青藏铁路GSM—R系统正式开通运行以来,GSM—R网络西宁侧TCU设备频繁重启,其承载的所有行车业务闪断,严重影响格拉线运输安全。引起TCU重启的原因较复杂,要明确TCU重启的真正原因,需要从网络结构、系统工作原理等多方面逐一分析查找。     

虚拟局域网技术在有线电视宽带网络中的应用研究

首先阐述了发展日益壮大的有线电视宽带网络中虚拟局域网(VLAN)技术的特点、划分方式,其次介绍了VLAN关键的ISL标签和VTP协议技术,最后对有线电视宽带网络中典型的Cisco Catalyst 6509 3层交换机基于端口的VLAN技术应用作研究分析.     

DX发射机控制单元24V电源故障及技术改造

本文以一故障为例介绍了DX600中波广播发射机控制单元24V电源故障对发射机安全播出造成的较大影响,阐述了利用TCU预留24V电源B实现即能备份TCU24V电源又能备份CCU24V电源的应急备份改造设计方案.     

虚拟局域网技术在有线电视宽带网络中的应用研究

首先阐述了发展日益壮大的有线电视宽带网络中虚拟局域网(VLAN)技术的特点、划分方式,其次介绍了VLAN关键的ISL标签和VTP协议技术,最后对有线电视宽带网络中典型的Cisco Catalyst 6509 3层交换机基于端口的VLAN技术应用作研究分析.     

虚拟局域网技术在有线电视宽带网络中的应用研究

首先阐述了发展日益壮大的有线电视宽带网络中虚拟局域网 (VLAN)技术的特点、划分方式 ,其次介绍了VLAN关键的ISL标签和VTP协议技术 ,最后对有线电视宽带网络中典型的CiscoCata lyst 6 5 0 93层交换机基于端口的VLAN技术应用作研究分析。     

关于HXD2机车TCU电子插件箱故障原因分析及解决办法

针对大秦线HXD2机车TCU电子插件箱故障导致机车电机隔离问题情况,深入查找了TCU故障原因并提出解决办法,有效解决了TCU由于电子插件箱故障引起电机隔离致使机车质量不稳定的情况,保证了大秦线运输运量的顺利完成。     

基于三层交换的VLAN设置技术研究

基于三层交换与路由技术的交换机的应用,已从最初网络骨干层、汇聚层渗透到接入层。论文对三层交换和路由技术、Trunk和VTP技术、VLAN技术的应用进行了全面详尽的描述,并介绍了思科交换机的VLAN配置方法。     

DX-600中波发射机TCU机柜中TCU及CCU电源箱的分析及故障判断

DX-600中波发射机TCU机柜中的TCU及CCU电源箱作为发射机控制系统的电源提供者,其重要性可想而知。本文通过对TCU及CCU电源箱的分析,介绍了故障预想、故障模拟及重要工作点电压检测等实践的经验,可为同类机型在排除故障时提供参考。     

电控机械式自动变速器在线故障诊断系统的开发

根据电控机械式自动变速器系统的特点,采用基于模型的设计方法,在MATLAB／SIMUuNK软件环境下,运用Stateflow逻辑系统建模工具建立了AMT系统的在线故障诊断模型,从而有效地对AMT系统中的传感器、执行机构和TCU硬件的主要故障进行在线诊断。大量试验表明,该设计方法是行之有效的且非常实用。     

基于方差时间图法的关键参数选取方法

在深入研究方差时间图法(Variance-time plots,VTP)的基础上,针对VTP算法中的3个关键参数:数据块数、采样数据长度和数据更新度参数进行了详细测试研究,分别对三者给出比较恰当合理的具体值,并提出基于上述参数值的分布式拒绝服务(DDoS)攻击判决门限条件.     

低副瓣直线阵的最坏情况容差最优化方法研究

本文以激励系数为设计参量,讨论了直线阵的最坏情况容差最优化问题,给出了直线阵的最坏情况问题,固定容差问题和可变容差问题,研究了它们的新求解方法。固定容差问题将采用正多面体方法来求解,可变容差问题由一个双层迭代算法求解。可变容差问题以实际与理想方向图在容差域中的最大偏差为基准,协调阵列方向图的副(?)电平和激励系数的容差,使阵列方向图的副(?)电平满足所希望的指标要求,同时尽可能地放宽激励系数的容差,文中最后给出了6元和16元直线阵的最坏情况容差最优化的模拟计算结果。     

Performance management of multiple access communication networks

This paper focuses on conceptual design, development, and implementation of a performance management tool for computer communication networks to serve large-scale integrated systems. The objective is to improve the network performance in handling various types of messages by on-line adjustment of protocol parameters. The techniques of perturbation analysis of Discrete Event Dynamic Systems (DEDS), stochastic approximation (SA), and learning automata have been used in formulating the algorithm of performance management. The efficacy of the performance management tool has been demonstrated on a network testbed. The conceptual design presented offers a step forward to bridging the gap between management standards and users' demands for efficient network operations since most standards such as ISO (International Standards Organization) and IEEE address only the architecture, services, and interfaces for network management. The proposed concept for performance management can also be used as a general framework to assist design, operation, and management of various DEDS such as computer integrated manufacturing and battlefield C³ (Command, Control, and Communications)     

基于WinCE的网络嗅探器的设计与实现

网络嗅探器是网络数据包捕获和解析的基本工具.提出了一种基于WinCE嵌入式系统网络嗅探器的设计和实现方案,利用了Winpcap库函数实现网络数据包捕获功能,分析了Winpcap和NDIS网络驱动程序的结构与联系,给出了网络数据包的传递与解析流程,并将Winpcap在WinCE平台上进行移植.经应用测试表明,该网络探嗅器具有较好的系统兼容性和广泛适用性.     

Transient thermal management of temperature fluctuations duringtime varying workloads on portable electronics

This paper describes the investigation of solid to liquid phase change materials (PCM's) for passive energy storage during the condition of time varying workloads on portable electronics. The model investigated includes a thermal control unit (TCU) embedded in an epoxy polymer. A TCU is an enclosure that contains phase change material (PCM) and a thermal conductivity enhancer, is located near the power source, and acts as an energy storage and heat-spreading module. Physical experiments were carried out to investigate the performance improvements of introducing a TCU into an embedded system and were used to validate the accuracy of the numerical model. Numerical simulations were performed to study the effect duty cycles and substrate thermal conductivities have on the thermal performance of the electronic wearable computer system with passive energy storage. Additionally, the TCU was numerically modeled to determine the influence of boundary conditions on TCU performance. To quantify the improvements of the system, metrics were developed from analyzing the thermal evolution of the TCU parameters, such as temperature fields, temperature bands, PCM characteristics, and power loads. Results indicate that using a TCU for passive energy storage significantly increases the portable electronics system's operational performance. Duty cycles with the same average power over the duration of the cycle do not influence the length of the PCM phase change time, but do impact the mean value of the temperature fluctuation bands     

Building a Normative Decision Support System for Clinical and Operational Risk Management in Hemodialysis

This paper describes the design and implementation of a decision support system for risk management in hemodialysis (HD) departments. The proposed system exploits a domain ontology to formalize the problem as a Bayesian network. It also relies on a software tool, able to automatically collect HD data, to learn the network conditional probabilities. By merging prior knowledge and the available data, the system allows to estimate risk profiles both for patients and HD departments. The risk management process is completed by an influence diagram that enables scenario analysis to choose the optimal decisions that mitigate a patient's risk. The methods and design of the decision support tool are described in detail, and the derived decision model is presented. Examples and case studies are also shown. The tool is one of the few examples of normative system explicitly conceived to manage operational and clinical risks in health care environments.      

一种用于光通信网络质量保障的保护路由算法

为了实现对光通信网络的质量保障,文章介绍了一种保护路由算法的设计和实现,它可用于在一个网络图中寻找两条不重合的最短路,同时也保证了这两条路径不存在共享风险的链路,最后设计了一个应用此算法方案的网络规划工具对寻找保护路由功能进行测试,从路由结果可见此方案的正确性。     

应用型本科院校网络协议分析课程实验教学改革研究——以福州理工学院为例

在网络协议分析课程现有的实验教学环节中存在实验项目老旧、缺乏创新、脱离实际应用等问题,无法满足网络协议分析课程的“三维”职业能力培养目标。因此提出一种基于协议编辑的实验教学方法,通过协议编辑工具,从报文编辑、协议设计、协议安全性等维度考虑进行实验项目设计探索和改进,并结合案例,给出了该方法在网络协议分析课程实验教学中的实施过程,为传统网络协议分析实验教学进行重要填补。     

PCM thermal control unit for portable electronic devices: experimental and numerical studies

This paper investigates the effectiveness of a thermal control unit (TCU) for portable electronic devices by performing experimental and numerical analyses. The TCU objective is to improve thermal management of electronic devices when their operating time is limited to a few hours. It is composed of an organic phase change material (PCM) and a thermal conductivity enhancer (TCE). To overcome the relatively low thermal conductivity of the PCM, a TCE is incorporated into the PCM to boost its conductivity. The TCU structure is complex, and modeling an electronic device with it requires time and effort. Hence, this research develops approximate, yet effective, solutions for modeling the TCU, which employ effective thermo-physical properties. The TCU component properties are averaged and a single TCU material is considered. This approach is evaluated by comparing the numerical predictions with the experimental results. The numerical model is then used to study the effect of important parameters that are experimentally expensive to examine, such as the PCM latent heat, Stefan number, and heat source power. It is shown that the TCU can provide a reliable solution to portable electronic devices, which avoids overheating and thermally-induced fatigue, as well as a solution which satisfies the ergonomic requirement.     

Automated modeling and analysis of CSMA-type access schemes for building automation networks

During the design of large technical systems, the use of analytic and simulative models to test and dimension the system before implementation is of practical importance for an efficient and reliable design process. However, setting up the necessary models is time-consuming and therefore often too expensive in practice. Usually most information for modeling is already available in the design tool used to develop such extensive systems and only needs to be extracted for automatic model building. This paper presents an automated modeling approach from an existing design database using the example of a network analysis for building automation fieldbuses. The analysis is based on an analytical decomposition approach that enables fast estimation of performance measures for large-scale networks. The combination of fast analytical algorithms with automatic model generation allows network performance engineering with minimized effort for model generation and analysis.