Income, Time Effects and Direct Preferences in a Multimodal Choice Context: Application of Mixed RP/SP Models with Non-Linear Utilities

Transport problems typically involve at least two types of constraints, on income and on time. Therefore, the indirect utility function depends either on the income available after having subtracted the cost of the discrete alternative and on the free time left after having worked and travelled by each competing option. In the typical linear-in-the-attributes and in-the-parameters specification, that represents the first grade approximation of the indirect utility function, the effect of income and time constraints cancel out and only the cost and time of the alternatives matter in the comparison between them. From a microeconomic point of view this is equivalent to assume that income and time effects could be disregarded; which is not always the case. To account for these effects the utility function should include second order attributes; however, in non-linear utility functions it may not be easy to distinguish among several effects that could be relevant: direct preferences for good and leisure, and simple interactions between attributes other than income and time effects. This paper analyses these effects from a theoretical point of view focusing on the possible confounding problem in detecting income and time effects. We use a dataset collected for a modal choice context and containing both revealed and stated preference data, and estimate several NL models examining the effect of the different second-order terms on detecting income and time effects. We compared specifications including square cost and time attributes, interactions between time and cost, cost divided by the income available to be spent on free time, and time multiplied by free time. Our results confirm the strong effect of direct preferences for goods and leisure time on choice, and the potential confounding effect between quadratic attributes and other non-linear omitted terms. Finally, we also found that care should be taken in highlighting income and time effects using mixed data sources, since confounding effects can occur when non-linearities are accounted for in both data sets.     

矿物质催化合成SP及SP-C

探索出一种以矿物质（橡胶填充剂）为催化剂合成ＳＰ及ＳＰ－Ｃ的新工艺。选择了最佳的工艺条件。此法制成的ＳＰ及ＳＰ－Ｃ产品性能优良、质量稳定。     

不同尺寸段塞组合等流度二元驱驱油效果评价

辽河油田锦16块实施二元复合驱以来,仍存在部分注入井单层吸液量过大,使注入液在各层中的推进速度不一致,从而导致相应的采油井聚合物质量浓度上升较快的问题。通过室内驱替实验,采用均质岩心和非均质岩心,对比不同段塞组合的等流度二元驱驱油方法在非均质岩心上的驱油效果。结果表明,在相同聚合物用量和总注入孔隙体积倍数条件下,在三层非均质岩心上等流度驱油方法比常规单段塞驱油方法化学驱采出程度高出3.54%;多段塞等流度驱油方法可以明显提高中、低渗层分流率,降低高渗层分流率。因此,合理段塞组合等流度二元驱油方法可有效提高高渗透非均质油藏的采收率。     

对等服务器网络模式

C/S模式具有较好的可管理性和稳定性,但不能自适应客户数量的变化.P2P模式可自动适应网络规模的变化,但可管理较差.对等服务器网络(P2SP)模式融合了C/S和P2P两者的技术优势,可以提高信息服务的质量,同时控制系统的成本.分析了P2SP的结构和特点,并给出了P2SP目录服务器的结构和信息认证模型.     

基于SAML2的单点登录服务器FAAS的设计与实现

单点登录是实现集中身份认证和数据统一管理的一种访问控制方法,它能够解决分布式系统的多重认证问题.在对单点登录以及安全断言标记语言(SAME)分析的基础上,设计和实现了基于SAML2的单点登录服务器FAAS(联邦认证授权服务器),并成功用于某上市企业ERP开发集成项目中.该设计的重点是SAML2的协议实现和FAAS的架构.     

一种卷板填充分层递归排样的优化算法

研究了卷板填充排样问题,提出了一种分层递归排样的优化算法。算法使用水平剪切线将卷板分层,每层的宽度和卷板宽度相同,高度和层最左端的主毛坯高度相同;通过调用递归过程确定卷板中层的排列,为各层选定主毛坯,并确定毛坯的排列方式;采用分支定界技术缩小搜索空间。实验结果说明该算法比文献中最近报道的几种算法都有效。     

一种L~E波段的A型上电极MEMS单刀三掷开关设计

针对单刀多掷开关(SPMT)在相控阵雷达、宽带收发器中用于切换滤波器和传输线时需要满足宽频带、高隔离度的性能需求,设计了一种宽频带、高隔离度的MEMS单刀三掷开关(SP3T)。通过ANSYS电磁仿真软件中的HFSS模块对MEMS SP3T开关进行优化,利用COMSOL软件对上电极的机械性能进行仿真。仿真结果表明,所设计的MEMS SP3T开关可工作在1~90 GHz的频带内,且插入损耗小于1 dB@90 GHz,隔离度大于35 dB@90 GHz,其整体体积约为0.75 mm³。     

基于H.264标准的多视点视频编码方案的研究

为研究一种新的高效的多视点视频编码方法,提高编码效率,并有效地提高视点间随机切换访问的能力,利用H.264中的新技术多参考帧、SP/SI帧、分层B帧编码等,根据时空预测编码结构的方法,提出了一种基于分层B帧并有利于视点间随机切换访问的多视点视频编码方案.实验结果表明,该方案在提高了编码效率的同时,在视点较多的情况下能够有效地提高视点间随机切换访问的能力.     

CC$:一种面向分布式众核平台的并行编程语言

CC$是一种并行编程语言,目的是解决分布式众核并行计算机的编程困难。CC$的编程模型以Multi BSP 模型为基础,将分布式众核并行计算机的硬件架构抽象为3层。数据按照存储的层次和共享范围分为5类,以便在不 同层次上提供共享。LL$还提出一类虚拟指令来解决不同层次之间的数据交换,实现数据访问的逻辑化描述。并行 程序按照3层Multi BSP超步嵌套执行。CC$具有统一的编程风格、内建的多层会共地址空间、数据访问请求的表达 式描述和数据传输编译优化4大特点。测试表明,CC$程序的运行效率高,易学易用,大幅地缩短了开发周期。     

以太网基于优先级的流控仿真设计

互联网在飞速发展的同时,也给网络系统的正常运行带来了一系列的问题,其中最突出的是由网络流量过大引起的网络拥塞。通过对多种流控方法的研究,最终从队列调度方面着手,利用OPNET网络仿真软件对所设计的三种流控机制进行仿真,初步解决了以太网较高优先级的数据流无法得到及时响应的问题以及公平性问题。