空间复用令牌协议错误检测机制的QoS

传统无线令牌环协议具有一定的错误检测机制,但没有对其服务质量(QoS)性能进行系统研究和分析. Ripple和改进型无线令牌协议等空间复用令牌协议令牌传递不同步,没有任何错误检测机制. 基于此,提出一种令牌自产生的概念,通过将其与固定令牌持有时间机制相结合,采用计时器队列实现空间复用令牌协议多令牌同步并行传递,在此基础上提出基于邻居监听的错误检测机制,并对算法的QoS指标进行了理论分析和仿真. 仿真结果表明,该机制可及时检测网络错误并进行有效处理,正确检测概率较高,适合在无线空间复用令牌网络中使用.     

基于子队列的分布式动态令牌中继协议

为降低短波令牌协议(HFTP)令牌中继延迟,提高中继成功率,提出一种新型无冲突的分布式
令牌中继协议(SQ DTRP). 该协议通过引入令牌中继子队列,提出增加通信对象项以最大限
度保存网络实时状态信息,实现动态搜索令牌中继路径,克服了HFTP令牌中继机制存在的应
答冲突和公平性问题. 仿真结果表明,该协议令牌中继时延和中继成功概率明显优于HFTP,
适合包括短波(HF)网络在内的各种无线网络使用.     

一种提高交换式网络服务质量的算法

服务质量QoS是提高网络性能的一种保障机制.它可以区分实时数据和普通数据,使实时数据及时得到服务,降低实时数据的响应时间.探讨了在交换式以太网中的QoS实现:先采用令牌桶对输入的数据流整形,采用尾部丢弃算法管理队列;在基于流的加权公平队列(WFQ)基础上,提出考虑优先级的WFQP算法调度数据包到出口链路.最后采用OPNET对这些技术进行仿真,分析和仿真结果表明,WFQP算法进一步提高了网络的实时性能,更有效地保证了实时信息的传输.     

一种控制网关流量的控制器设计

提出扶持共享带宽的双令牌桶流量分配算法.基于此算法,设计了对网络服务监控网关中的流量控制所涉及的分类、过滤、限制等.     

支持链路共享的流量整形器

针对英特网的一些接入场合，特别是有服务质量（QoS）要求的场合，对共享一条物理链路
的多个逻辑链路的分组流量进行整形。引用分级链路共享树概念，对应每个类设置一个令牌桶，使得在实
现分级链路共享的同时可以对任意一个类的业务流进行整形，限制其速率和突发。对于带宽不需要限制的
类，改进基于令牌桶的调度算法，使这些类具有借用空余带宽的能力，以便提高带宽利用率。理论分析和
仿真结果表明，该流量整形器通过依权重公平分享令牌途径，保证每个类的基本带宽服务并可以依权重公
平分享空余带宽，从而实现高效的分级链路共享功能。     

基于两色标记器的协作可调整RED算法

在区分服务网络中提出与两色标记器协作的RED改进算法--协作可调整RED算法(CARED)。通过对两色令牌桶标记器的流量特性进行分析,获得了标记概率与服务实际速率/承诺速率间的定量关系,并根据这个关系调节CARED中的丢包概率基数。为便于实现CARED算法,还提出了一种基于包数的滑动窗口标记概率测量算法(NSWM)。仿真实验证明了CARED算法不仅为区分服务网络提供了有效的拥塞控制功能,同时保障了区分服务的性能要求和公平性。     

基于IXP2400的流量监控技术研究

网络流量监控是网络流量管理的基础和重要内容。通过对基于网络处理器IXP2400网络流量监控技术的研究,分析了IXP2400的功能特性,并对基于硬件的哈希运算、令牌漏桶算法等关键技术做了详细的描述,最后用微码编程实现了网络数据包监控的模拟仿真。     

以太网与控制网的性能仿真评估研究

主要讨论了以太网和控制网的网络工作机理,对以太网总线和控制网总线的介质访问控制(MAC)的子层协议,采用带碰撞检测的载波侦听多点访问方式(CSMA/CD)和控制网的令牌传送总线作了详尽的比较,并用仿真方式比较了它们的传输时间和数据编码效率.     

任意拓扑结构Ad hoc网络的分布式一致性算法

为了解决Ad hoc网络中的分布式一致性问题,在对其特性分析的基础上,提出了新的Ad hoc模型以及新的Ad hoc分布式一致性算法ADC (Ad hoc Distributed Consensus)。这种算法基于传统的令牌查询,使用广播在任意拓扑结构的网络中查找令牌,同时,该算法使用带有Lamport时戳的请求消息和动态队列。较之传统算法,它能够较好的适应Ad hoc网络中节点频繁出入的情况。仿真与分析结果表明：该算法具有较低的消息复杂度、较小的空间复杂度和较短的响应延迟。     

一种容错增强的电子织物网络

在已有的电子织物令牌阵列网络的基础上,提出一种容错增强的电子织物网络.新的增强网络采用令牌环正反向交替运行机制和简单路由表机制,并与已有网络进行仿真比较.结果显示,此增强网络的容错性能明显优于已有网络.     

Reliability-based maintenance scheduling of hydraulic system of rotary drilling machines

Hydraulic system has a critical and important role in drilling machines. Any failure in this system leads to problems in power system and machine operation. Since the failure cannot be prevented entirely, it is important to minimize its probability. Reliability is one of the most efficient and important method to study safe operation probability of hydraulic systems. In this research, the reliability of hydraulic system of four rotary drilling machines in Sarcheshmeh Copper Mine in Iran has been analyzed. The data analysis shows that the time between failures (TBF) of Machines A and C obey the Weibull (2P) and Weibull (3P) distribution, respectively. Also, the TBF of Machines B and D obey the lognormal distribution. With regard to reliability plots of hydraulic systems, preventive reliability-based maintenance time intervals for 80% reliability levels for machines in this system are 10 h.     

实时二叉判定图

对布尔函数的有效操作是许多计算机辅助设计的重要组成部分,二叉判定图（ＢＤＤ）是对布尔函数的一种有效表示,为了表示带时间参数的布尔函数,在ＢＤＤ的基础上,本文给出了带时间参数的布尔函数（ＴＢＦ）的表示—带时间参数的二叉判定图（ＴＢＤＤ）,并利用ＣＵＤＤ包实现了ＴＢＤＤ．     

phen—TBF—CTMAB多元络合物光度法测定微量银的研究

本文研究了用Ag(Ⅰ)——phen——TBF——CTMAB多元络合物测定微量银的新方法、该络合物在PH2.52—5.31范围的最大吸收波长为545nm。它发色迅速,摩尔吸光系数为8.4×10~4。当用EDTA2Na—作金属离子的掩蔽剂时,银量在O—20ug/25ml符合比尔定律。这个分光光度的新方法应用于废水中     

Analysis of asphalt pavement structural response from an accelerated loading test

This study was to compare theoretical calculation and practical measurement structure response of asphalt pavement. Analysis of the pavement layer moduli was determined from a Back-calculation of Falling Weight Deflectometer (FWD) data and the measured stiffness moduli of asphalt layer cores. The pavement response was calculated using a theoretical model and the measured strain response at the bottom different layers. Layered elastic theory was used to back-calculate the layer moduli and three different theory models were used to forward calculate the strain and deflection. The models were: Layered Elastic Theory (LET), the Method of Equivalent Thicknesses (MET) with linear elastic and the Finite Element Method (FEM) where asphalt layer may be viscoelastic. The results showed that the calculation structure response from FEM was consistent with measured results.     

基于能量有限元方法的声腔内部噪声预测

为了预测声腔内部噪声,基于能量有限元方法(EFEA)建立了声腔-平板-声腔的EFEA耦合模型,对声腔内部噪声进行了数值计算。建立了声腔-平板-声腔的统计能量分析(SEA)模型,并将EFEA模型的预测结果与SEA模型的预测结果进行了对比。结果表明,二者具有较好的一致性。建立了声腔-前风挡玻璃-声腔的EFEA耦合模型和SEA耦合模型,分别对EFEA和SEA模型的外侧声腔响应进行了仿真分析,并与试验结果进行了对比。结果表明,EFEA预测结果与SEA预测结果以及试验结果均吻合良好,充分显示了本文所建立的声腔-前风挡玻璃-声腔EFEA模型对声腔内部噪声预测的准确性。     

Research on the Control Strategy of Variable Nozzle Turbocharger for Natural Gas Engine

A variable nozzle turbocharger (VNT) was applied to a 2.2-liter L4 natural gas engine,and a VNT control system was designed to operate it.Based on VNT matching test results,a VNT control strategy was studied,in which VNT adjustment is carried out through pre-calibrated VNT handling rod position,combined with a closed-loop target boost pressure feedback using proportional-integral-derivative(PID) algorithm.Experimental results showed that the VNT control system presented in this thesis can lead to optimized ...     

Effects of C_(60) on the Glass Transition Temperature of Carbazole-based Photorefractive Polyphosphazenes

The bi-functional carbazole-based photorefractive polyphosphazenes with different content of C_(60)-doped were fabricated. The glass transition temperature(T_g) of these polymer composite materials was determined using a differential scanning calorimetric(DSC) method. According to the DSC measurement results with different heating rates, the variation of T_g and the active energy of glass transition(E_g) were analyzed in detail. The analysis results indicate that the transition region shifts to higher temperatures with increasing heating rate, and C_(60) content(below 1.0 wt%) can influence the T_g of photorefractive polyphosphazenes. The T_g first increases and then decreases with the C_(60) content(below 1.0 wt%). The probable causes of the influence of C_(60) on T_g was proposed.     

Mathematical modeling of fluid flow, heat transfer and inclusion transport in a four strand tundish

Mathematical simulation was used for trouble-shooting and optimization. By the mathematical simulation, fluid flow and beat transfer of molten-steel in a four-strand tundish of a billet caster under different conditions （bare tundish and tundish with flow control device） were analyzed, The results showed that （1） the tundish with flow control device （FCD） has an important effect on the fluid pattern and temperature distribution; （2） the unsteady, solving method was used to model the inclusion motions at different time perthds, and it showed that the FCD is advantageous to separate the nonmetallic inclusions. According to the simulation results, the main problem existing in the industry preduction was found, and some helpful rneasurements were executed. Consequently, the large nonmetallic inclusions were separated, and the content of total oxygen was reduced. The qualily of steel was greatly improved.     

Sensitive determination of DNA based on resonance light scattering enhancement of azocarmine G and CTAB

A new method for the determination of DNA was developed with azocarmine G（AG） in the presence of cetyltrimethylammonium bromide（CTAB） by the resonance light scattering （RLS） technique. The synthetic samples were determined with satisfactory results, and the reaction mechanism was also studied. The results show that under the optimum conditions, the weak RLS signal of AG can be enhanced by DNA, which results from the formation of a new ternary complex AG-CTAB-DNA with large size. Moreover, the enhanced RLS intensity at 552 nm is directly proportional to the concentration of DNA in the range of 0 - 1.0 μg/mL for fish sperm DNA （fsDNA） and 0 - 1.5μg/mL for calf thymus DNA （ctDNA）. Based on this, a new assay of DNA can be established. The detection limits （3σ） are 2. 1 ng/mL for fsDNA and 2.2 ng/mL for ctDNA, respectively.     

应用PSO和SVM的水下航行器黑箱建模

随着新型水下航行器不断涌现,现有水下航行器数学模型已难以与实际模型吻合.为更好了解新型水下航行器实际模型以及预测新型水下航行器运动,提出应用粒子群(particle swarm optimization,PSO)参数寻优和支持向量机(support vector machine,SVM)的水下航行器黑箱建模方法.首先根据水下航行器的运动状态信息和推进器力,应用支持向量机构造出之间的非线性映射关系,然后通过粒子群智能优化算法获得支持向量机的最佳参数组合,进而实现水下航行器的黑箱建模,最后根据推进器力是否时变,分别以新型四旋翼水下航行器的两种空间运动进行实验验证,并以均方根误差作为空间运动预测结果的评价标准.试验结果表明,基于粒子群参数寻优和支持向量机所构建的水下航行器黑箱模型对空间运动预测具有较小的均方根误差,空间运动预测结果与实际运动基本一致,所建黑箱模型与实际模型基本吻合,能有效预测水下航行器运动状态.