剪切作用定量影响含蜡原油蜡晶形态的机理

由于含蜡原油中蜡的形态、结构是影响原油流动性的主要因素,通过研究剪切作用定量影响蜡晶形态、结构的机理,将有助于研究剪切作用影响原油流动性的机理.为此,以蜡晶形态参数为因变量,以表征剪切模拟量的参数粘性流动熵产,以及原油化学组成参数为自变量,建立了定量关系式.定量关系式显示,含蜡原油在析蜡点以下的温度被剪切时,剪切作用与原油的化学组成可显著影响蜡晶的形态、结构.粘性流动熵产越大,原油蜡含量与析蜡量越高,胶质含量越低,则蜡晶聚集体越容易被破坏.     

轨道交通延误条件下列车跳站与客流控制协同优化模型

针对城市轨道交通突发列车延误问题,统筹考虑行车秩序的恢复和乘客出行体验,提出列车调整与客流控制协同优化方法。首先分析延误条件下城轨列车调整和客流控制的措施及效果,构建以跳站停车和多车站客流控制为手段的双层线性规划模型。上层模型以列车总延误最小为目标,以列车载客能力为约束;下层模型以上车客流量最大为目标,以列车载客能力和控流率均衡为约束。采用灵敏度分析算法求解模型,并以北京地铁亦庄线故障延误事件为例,验证模型和算法的有效性。结果表明：采用跳站停车与进站客流协同控制可使延误列车行程时间缩短5.2%,使各车站进站率方差降低97.8%,在保障乘客公平性的条件下提高列车运行和乘客集散效率。     

几种疲劳裂纹扩展模型的比较分析

研究疲劳裂纹扩展机理以及评估结构疲劳强度的“单参数模型”和“双参数模型”对疲劳裂纹扩展的三个阶段—门槛值附近、稳定扩展阶段、失稳阶段的描述能力存在较大差别.文章就现今主流的以McEvily模型为源头的一系列单参数模型、双参数模型、统一模型以及正切模型进行了探讨,分析了这些模型对疲劳裂纹扩展的描述能力以及在疲劳寿命评估方面的差别.     

潜艇耐压结构径向初挠度计算方法试验

针对评定潜艇肋骨初挠度时寻找评定中心不准确的现状,本文利用全站仪进行测量获取母线划分点的二维坐标,并采用评定圆度误差的4种方法的拟合圆心作为初挠度的评定中心对其初挠度进行评定。试验结果表明,最小区域圆法评定精度最高,最小外接圆法和最大内接圆法的评定精度次之,最小二乘圆法评定精度最低。不同的工况可以选择适合的方法,可以提高潜艇耐压结构的建造效率与质量。     

Synergies between Adjacent Beach-Nourishing Communities in a Morpho-Economic Coupled Coastline Model

Beach “nourishment” consists of placing sand on an eroding beach. The widened beach provides increased storm protection to adjacent structures and improved recreational benefits, but is most often transient, requiring on-going, repeated nourishment episodes. Numerical models of beach nourishment typically address such questions as how long a widened beach will last; economic models compare the benefits and costs of preserving a stretch of beach without regard to its geomorphic evolution. Neither have addressed the physical nor economic interactions between adjacent nourishing communities. Here, we couple a numerical model of coastline evolution and a cost-benefit model of beach nourishment, allowing adjacent communities to make dynamic nourishment decisions. Beach nourishment benefits adjacent communities both “updrift” and “downdrift.” The total amount of money spent on nourishment activities can decrease by as much as 25% when adjacent communities both conduct on-going nourishment projects, as opposed to the case where each community nourishes in isolation.     

Determinants of motor vehicle crash fatalities using Bayesian model selection methods

Motor vehicle crashes continue to result in large numbers of fatalities each year and represent the leading cause of death for young persons. In 2006, for example, there were over 42,700 fatalities associated with these crashes. Understanding the causes of these crashes and methods to reduce them continues to be of great interest to economists, public health officials, and policy makers. We present in this paper statistical models using a rich set of panel data covering the period 1980 to 2007 by state and the District of Columbia. Our choice of variables is based on an extensive literature highlighting the importance of policy, safety, demographic, and economic determinants of fatality rates.     

Collaborative Management of Natural Resources in San Diego Bay

This article presents the results of a three-year effort at applying information technology to the problem of collaborative natural resource management in San Diego Bay. As such, it represents an approach to integrated coastal zone management (ICZM). This effort resulted from a collaboration between the San Diego Supercomputer Center at the University of California, San Diego and the San Diego Bay Interagency Water Quality Panel for the purpose of (1) developing an environmental data repository to facilitate the acquisition and sharing of data and (2) the development of a visual model of the bay in support of the development of a comprehensive, coordinated management plan for San Diego Bay. It was determined from this study that information technology is an important and key component to ICZM but that sociopolitical factors may override the benefits of decision-support systems and should be considered at the outset of any project of this kind.     

浅谈海洋石油平台橇内仪表设计与安装

在橇块项目建设中,仪表专业占据着20%左右的比重。与相关各专业有着千丝万缕的联系,且本专业点散面广,类型繁多,在工程实施过程中首先要做好设计与选型,再充分理顺各专业及工序间的关系,才能保证按期优质完成任务,促进整个项目的顺利进行。     

基于组态软件WinCC的船舶监测报警系统的设计与研究

船舶监测报警系统是保证船舶安全、可靠、高效运行的重要组成部分。结合现代工业与船舶监测报警功能的需要,论述了以工业组态软件WinCC为基础的船舶损管及火灾监测报警系统软件的设计、研究及其能够实现的具体功能,并对系统主要参数如网络速度、动态响应时间、数据采集、归档周期等进行了说明,也对组态软件相对于其他编程软件的优势以及硬件的组成部分、软件与硬件的通讯方法和过程作了简要介绍。     

嵌入式平台视频通信系统的设计与实现

利用X.264视频压缩编码在嵌入式平台上进行实时视频通信系统前台和利用FFMPEG视频解码在linux平台上进行实时视频通信系统后台。实现了视频通信嵌入式系统的设计与开发,该系统具有视频采集和存储、无线网络传输等功能。该设计适用面广,用户计费流量低,功能实用可靠。