改进型并行比特翻转算法(英文)

提出一种改进的并行比特翻转算法. 为了加快校验节点和变量节点之间的信息传递速率, 算法中的比特翻转及校验和更新2个步骤采用并行化处理. 仿真结果表明, 改进后的算法相对于原有的并行比特翻转算法在误帧率性能上能够取得0.1～0.3 dB的增益. 同时, 改进算法在译码吞吐率的性能上也有所改善. 此外, 还讨论了翻转门限的选择方法, 这些门限决定了每次迭代中哪些比特需要被翻转. 通过选择合适的翻转门限, 可使错误的比特尽量多地被翻转, 并避免翻转正确的比特. 该改进算法比较适用于对具有准循环结构的LDPC码进行译码.     

普通公路交通标志设置效用调查研究

根据驾驶人视认过程确定交通标志设置效用的影响因素,建立基于集对分析理论的交通标志设置效用综合评价体系。利用“鱼骨图”分析法,确定了交通标志设置效用指标评价体系,并通过层析分析法计算各评价指标权重值,借用集对分析理论进行联系度计算,最终得到交通标志设置效用的综合评价值。最后,以国道316永辉-洪山桥路段现状交通标志设置为例,利用已构建集对分析评价模型确定该路段交通标志设置效用等级,并结合评价结果提出相应的改善建议。     

Optimal design of pressure vessel using an improved genetic algorithm

As the idea of simulated annealing （SA） is introduced into the fitness function, an improved genetic algorithm （GA） is proposed to perform the optimal design of a pressure vessel which aims to attain the minimum weight under burst pressure constraint. The actual burst pressure is calculated using the arc-length and restart analysis in finite element analysis （FEA）. A penalty function in the fitness function is proposed to deal with the constrained problem. The effects of the population size and the number of generations in the GA on the weight and burst pressure of the vessel are explored. The optimization results using the proposed GA are also compared with those using the simple GA and the conventional Monte Carlo method.     

Internet流量与负载均衡的研究

Load and traffic balancing for the Internet are analyzed. An intelligent domain name system(DNS) policy for the control and management of content distribution networks (CDN) is presented. An CDNs network based Urtitech IntelliDNS is built, and performance of the network in realizing traffic and load balancing is measured. It is proved that CDNs provide a valuable service and the methods are feasible.     

聚类分析和逐步回归法在车道流量预测中的综合应用

针对目前国内外大中城市中普遍存在的无检测器信号交叉口车道交通流信息难于获取的情况,基于信号控制交叉口车道之间的相关性,综合应用聚类分析和逐步回归法预测单点无检测器信号控制交叉口车道流量.首先应用聚类分析将单点无检测器信号控制交叉口的车道与有检测器信号控制交叉口的车道交通流量进行聚类,然后在聚类分析结果的基础上随机选取车道交通流量样本运用逐步回归法预测单点无检测器信号控制交叉口的车道流量,此方法经过南京市的具体车道流量数据验证.此类问题的解决,可广泛应用于城市交通流诱导系统以及交通控制系统.     

基于CTM的大型活动突发事件交通影响范围确定(英文)

为了确定大型活动下突发事件的交通影响范围,以元胞传输模型(CTM)为基础,对大型活动中消散过程中交通流时空分布状况进行模拟研究.结合突发事件下常用的交通管制和疏导措施的特点,将静态多路径交通分配方法与元胞传输模型结合,设计出适合突发事件下的准动态交通分配方法.以一个小规模路网为研究对象,通过仿真研究了大型活动条件下路网交通流随交通控制方案的实时调整而变化的时空规律,提出了依据突发事件下各交叉口节点的拥堵时刻划定突发事件交通影响范围的方法.通过对比车辆的平均延误指标,研究了不同交通管控方案下交通拥堵的疏散效率.算例结果表明,基于CTM的准动态交通分配方法可以细致地描述路网中任一位置交通流的时空变化,确定突发事件的动态影响范围,可以为大型活动突发事件下交通组织方案的制定和评价提供定量依据.     

校园网流量自相似特性的研究

针对校园网流量自相似特性的问题,以网络中心测得的实际网络数据为研究对象,对不同时间尺度内的分组到达数目进行研究。利用方差-时间曲线和R/S图方法对实际流量数据进行测量、分析和预测,证实校园网流量具有典型的自相似性。     

A load-balanced minimum energy routing algorithm for Wireless Ad Hoc Sensor Networks

INTRODUCTION Wireless Sensor Network is one special type of wireless ad hoc networks without fixed infrastructure consisting of a collection of sensor nodes, and oper- ating on limited amount of battery energy consumed mostly in transmission and reception. In the WSNs described in Fig.1, every sensor node can sense, process data and communicate to base station (BS). WSNs have attracted much attention during the recent two years and some commercial implementations such as environmental …     

Model predictive control for adaptive cruise control with multi-objectives: comfort, fuel-economy, safety and car-following

For automated vehicles,comfortable driving will improve passengers’ satisfaction.Reducing fuel consumption brings economic profits for car owners,decreases the impact on the environment and increases energy sustainability.In addition to comfort and fuel-economy,automated vehicles also have the basic requirements of safety and car-following.For this purpose,an adaptive cruise control (ACC) algorithm with multi-objectives is proposed based on a model predictive control (MPC) framework.In the proposed ACC algorithm,safety is guaranteed by constraining the inter-distance within a safe range; the requirements of comfort and car-following are considered to be the performance criteria and some optimal reference trajectories are introduced to increase fuel-economy.The performances of the proposed ACC algorithm are simulated and analyzed in five representative traffic scenarios and multiple experiments.The results show that not only are safety and car-following objectives satisfied,but also driving comfort and fuel-economy are improved significantly.     

Optimal time for mesenchymal stem cell transplantation in rats with myocardial infarction

Background:Bone marrow mesenehymal stem cell(MSC)transplantation is a promising strategy in the treatment of myocardial infarction(MI).However,the time for transplanting cells remains controversial.The aim of this study was to find an optimal time point for cell transplantation.Methods:MSCs were isolated and cultured from Sprague-Dawley(SD) rats.MI model was set up in SD rats by permanent ligation of left anterior descending coronary artery.MSCs were directly injected into the infarct berder zone at 1 h,1 week and 2 weeks after MI,respectively.Sham-operated and MI centrel groups received equal volume of phosphate buffered saline(PBS).At 4 weeks after MI,cardiac function Was assessed by echocardiography;vessel density Was analyzed on hematoxylin-eosin stained slides by light microscopy;the apoptosis of cardiomyocytes Was evaluated by terminal deoxynucleotidy1 transferase-mediated dUTP nick end-labeling(TUNEL) assay;the expressions of proteins were analyzed by Western blot.Results:MSC transplantation improved cardiac function.reduced the apoptosis of cardiomyocytes and increased vessel density.These benefits were more obvious in l-week group than in 1-h and 2-week groups.There are more obvious increases in the ratio of bc1-2/bax and the expression of vascular endothelial growth factor(VEGF)and more obvious decreases in the expression of cleaved-caspase-3 in 1-week group than those in other two groups.Conclusion:MSC transplantation was beneficial for the recovery of cardiac function.MSC transplantation at l week post-MI exerted the best effects on increases of cardiac function,anti-apoptosis and angiogenesis.     

Investigation on the temperature distribution and strength of flat steel ribbon wound cryogenic high-pressure vessel

INTRODUCTION Cryogenic high-pressure vessels are used to store liquid hydrogen and liquid oxygen, and are necessary equipments in the fields of chemical engineering, astronautic engineering and nuclear power plant, and so on. Safe operation of the vessel is always a concern of environmental protection. The inner pressure of the vessel can reach 40 MPa at temperature of 20 K; Therefore, the vessel requires high-performance wall material excellent in mechanical strength, plastic property,…     

Review of Research on Learning and Instruction with Specific Reference to Reading Chinese as an Additional Language (1976-2018)

This review, which can be seen as a scoping review, highlights 92 empirical studies about the learning and instruction of reading Chinese as an additional language (CAL) published in English between 1976 and 2018. It first identifies and evaluates the trends of CAL reading research over the past four decades, including the developmental trajectory of the field, topics that are hot versus those not-so-hot, populations that are widely studied versus under studied, research methods adopted in the selected studies, and the most widely cited articles. Second, the review examines direct evidence that supports effective practices of CAL reading instruction and explores two tracks of studies: high-evidence versus low-evidence practices. This review concludes with thoughts on the future directions of CAL reading research inspired by trends in the areas of literacy, second language acquisition (SLA), and teaching Chinese as a second/foreign language (TSCL/TCFL). To be specific, there is a need for the field to pay equal attention to learning to read and reading to learn.     

交通影响分析影响范围的确定

通过分析土地开发对交通的影响,提出进行交通影响分析的必要性.在分析现行确定交通影响范围方法的基础上,指出定性研究方法的不足.探讨了确定影响范围应考虑的用地开发强度、项目周边路网的状况、公交可达性、项目本身四项因素,提出确定影响范围的定量方法,给出计算公式,并指出了公式的不足之处.     

一种基于聚类与关联规则算法的DDoS攻击检测模型

分布式拒绝服务（Distribute Denial of Service）攻击是当前主要的网络安全威胁之一．本文分析了DDoS攻击的本质特征,提出了一种基于数据挖掘算法的DDoS攻击检测模型．该模型使用聚类算法与关联规则对网络流量与网络数据包连接状态分别建立特征模型,并确定DDoS攻击的检测阈值．实验表明,该检测模型能够实时有效的检测DDoS攻击．     

组织工程的一个初步研究混合多尿烷血管移植(英文)

本文的目的是研究半多孔内皮细胞的包膜(SPEUs)的效应 以PTMEG1000为基础的SPEU的多孔性为51.58%(±5.86%) 与天然脉管相比较,例如与一头6个月小牛胸部的上部下来的主动脉大血管相比较,SPEU的拉伸强度是足够强的 脉管的典型脉动压力服从静脉管压力(1.5～2%Δd/d),此压力小于动脉管压力(9～15%Δd/d) 在种植EC之前,观察了在SPEUs上培育的人皮的成纤维细胞(HDF) SPEU的DNA数量与HDF在一天之内种植;有71.9%(±11.01%)细胞被种植在SPEUs上 LDH试验表明:在有控制的和实验群数据之间没有显著的差别,说明没有细胞毒素 因此,EC在SPRUs上具有良好的粘附性,这是所期望的,而应用胶原实现了将EC种植在半微孔的SPEUs上的表面改善     

TDD-CDMA 系统中基于业务统计的联合功率控制算法

An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms.     

Risk-taking path choice behaviors under ATIS in transportation networks with demand uncertainty

A new travel time reliability-based traffic assignment model is proposed to investigate the effects of an advanced transportation information system (ATIS) on drivers‘ risk-taking path choice behaviours in transportation networks with demand uncertainty. In the model, drivers are divided into two classes. The first class is not equipped with ATIS, while the second class is equipped with ATIS. Different risk-taking path choice behaviours of the two classes are studied, respectively. A corresponding mixed equ...     

Adolescent English Learners’ Use of Digital Technology in the Classroom

This study looked at how five adolescent English Learners (ELs) in an English as a second language class use the available digital technology. Data collected consisted of classroom observations, student and classroom documents, and focus student interviews. Data collection and analysis were simultaneous processes. Findings suggest adolescent ELs use their personal smartphones and school-provided laptops on a regular basis for entertainment and scaffolding purposes.