网络贸易模拟——在贸易实战中培养学生的职业素质和能力

网络贸易模拟是一门实践性课程,该课程采用贸易实战的方式使学生通过模拟的网络商务环境独立地从事国际货物买卖业务,从而培养学生的职业素质和解决问题的能力。本文介绍了作者对如何在课程中有效地培养学生职业素质和能力的思考。     

国际智能交通系统研发热点

 智能交通系统（intelligent transport system,ITS）是现代交通的一项前沿技术,自1994年正式确定名称以来,迄今已发展了20多年。随着前沿技术的发展和出行者需求的变化,ITS领域出现了与以往不同的、特色鲜明的技术方向和研发热点。分析了近期国际ITS研发热点和最新动态,探讨了新一代信息技术带来的智能交通技术变革和热点领域变化,提出了智能交通系统演进的方向和产业方向。对照中国ITS近几年的发展,分析了国内外发展思路的异同以及发达国家研发热点的启示,对智能交通系统发展提出了建议,认为应实事求是地对待国内外的差距和异同、加强智能交通特色技术的研发、建立以产业推动为主的新发展模式等。     

Evolutionary relationship and species separation of four morphologically similar stichotrichous ciliates （Protozoa, Ciliophora）

Phylogenetic and taxonomic studies on ciliate protists using molecular approaches have been demonstrated to be very reliable to form strong conclusions and results. In the present work, species separation of some morphologically similar stichotrichous ciliates, two species of Pseudokeronopsis and two species of Apokeronopsis, was reexamined using amplified ribosomal DNA restriction analysis (PCRRFLP). Five of 10 restriction enzymes revealed species-specific polymorphic patterns, of which four similar stichotrichs could be significantly separated and identified. Among them, EcoR I offered almost no significantly different restriction fragment patterns, but the four species could be separated from one another and identified with Hae III. Distinctly different restriction digestion haplotypes and similarity indices separated the species, and were used to construct a phylogeny. Phylogenies based on ITS2 nucleotide sequences and ITS2 secondary structures supported the separation of Pseudokeronopsis and Apokeronopsis using RFLP analysis, although three Pseudokeronopsis carnea populations did not cluster together. In addition, phylogenetic analyses using multiple algorithms confirmed that these two genera formed two distinct groups within the urostylids.     

新疆羊肚菌rDNA的ITS序列分析

根据生境和形态学特征与大型真菌图鉴对照,从形体上挑选了4个羊肚菌子实体（其中3个来自哈密巴里坤,1个来自乌鲁木齐南山）,同时从四川绵阳某研究所购得一株高羊肚菌菌种做为实验阳性对照,为了确定收集的羊肚菌分类学地位,采用PCR技术,以rDNA—ITS为分子指标,对子实体和菌丝进行了ITS序列测定与分析,结合系统进化树确定品种归属。     

一种混合交通流微观模型仿真实现

充分考虑中国城域混合交通流的特点,利用马尔可夫过程理论对个体运动轨迹、行进方向及行为冲突进行建模,建立了由汽车、自行车和行人构成的混合交通流微观模型.在此基础上,进一步对个体交通行为进行描述和算法设计,并对西安市古城墙内区域各主干道混合交通流的交通行为进行了模拟验证.仿真表明,该模型具有结构简单、层次清晰和可扩展性强等优点.     

泡沫沥青用量和矿料级配对混合料拌和用水量影响

为了研究泡沫沥青用量和矿料级配对泡沫沥青混合料所需合理拌和用水量的影响,设计了3种矿料级配组成OA1、OA2和OA3,通过变化4种沥青用量2％、3％、4％、5％（相对于矿料干重的百分比）,5种拌和用水量,即混合料最佳击实含水率（OMC）的60％、70％、80％、90％、100％,将各组合下制备成的泡沫沥青混合料成型试件,测定其间接拉伸强度和干密度．结果表明：不同的矿料级配、泡沫沥青用量和拌和用水量条件下制备的泡沫沥青混合料具有不同的间接拉伸强度和干密度．不同的矿料级配和不同的混合料拌和用水量存在最佳泡沫沥青用量3％．综合推荐出泡沫沥青混合料OA1、OA2和OA3适宜的拌和用水量范围分别为65％～80％OMC、70％～85％OMC和75％～85％OMC．通过试验路的铺筑观测发现,使用状况良好,验证了此研究结果是合理的．     

一种简化的短波信道ITS模型

短波信道的仿真是建立在短波通信系统基础上的.目前公认最好的宽带短波信道模型是ITS信道模型,针对ITS信道模型仿真的复杂性,运用Nakagami函数,对ITS信道模型中的功率延迟剖面函数进行了拟合,得到相对简单的仿真模型.通过对功率延迟剖面分布函数的分析验证以及赤道信道条件下延迟等高线的比对,证明了运用Nakagami函数进行拟合后获得的简化模型的可行性与合理性.     

智能交通系统集成控制软件研究

智能交通已成为城市交通发展的趋势。由于不同时期会有不同的厂家进行交通设备的安装和软件系统的建设,因此很多交通管理部门会面临数量众多、不同类型的交通管理系统,影响到交管工作的效率。在此背景下,文中阐述了智能交通系统集成控制软件的设计思路和实现功能,该软件着重实现将不同种类、不同时期建设的交通管控系统整合到统一的框架下,并对用户提供统一的操作界面,软件系统可以与其他部门的系统进行数据共享,还提供未来建设的交通管控系统的接口,建立一个统一的可伸缩的智能交通信息采集、处理、分析和管理体系,提升交管部门工作的水平和效率。     

Series queuing network scheduling approach to co-scheduling model of three Gorges-Gezhou dam

<正> This paper provides a mathematical model for Three Gorges-Gezhou dam co-schedulingproblem,based on full analysis of Three Gorges-Gezhou dam's actual needs,to maximize the totalthroughput of Three Gorges-Gezhou dam and the utilization ratio of shiplock area and minimize thetotal navigation shiplock waiting time under multiple constraints.This paper proposes a series queuingnetwork(SQN)scheduling algorithm to divide the total ships that intend to pass through the shiplocksinto four queues and calculate dynamically the weight of priority for each ship.The SQN schedulingalgorithm schedules ships according to their priority weights which is determined by the characteristicsof each ship,such as length,width,affiliation,waiting time,and so on.In the process,the operationconditions of Gezhou dam related to the navigable shiplocks and the task balancing among differentshiplocks also should be considered.The SQN algorithm schedules ships circularly and optimizes theresults step by step.Real operation data from our project shows that our SQN scheduling algorithmoutperforms the traditional manual scheduling in which the less computational time is taken,the areautilization ratio of the five shiplocks is increased,the waiting time of high-prioritized ships is shorten,and a better balanced and alternating run-mode is provided for the three shiplocks in the Gezhou dam.