基于物联网的新一代智能交通

智能交通的概念已被社会所接受,并得到广泛的应用。与此同时,智能交通系统所存在的问题也日益显现,物联网的出现为智能交通的发展提供一条新道路。首先介绍物联网的概念、原理和结构;随后分析物联网对交通运输行业的影响,并重点阐述物联网与智能交通之间的联系,探讨基于物联网的新一代智能交通系统的体系结构;最后,展望基于物联网智能交通的应用前景。     

基于马尔可夫过程船舶电力系统可靠性仿真分析

船舶可靠性至关重要,该文采用马尔可夫过程,从接近实际情况出发,建立有别于以往的船舶发电系统的容量模型;从概率论出发,利用MATLAB,选择合适的模拟方法,模拟出电力负荷概率分布曲线,快速地建立负荷模型.创新性地应用电力不足概率法(LOLP)于船舶电力系统中,结合容量模型与负荷模型,得出船舶发电系统可靠性指标,为船舶发电机组的容量、台数以及预防性维修提供参考,有助于完善能量管理系统(PMS)功能,提高电力系统安全与经济运行水平.     

Estimating a model of dynamic activity generation based on one-day observations: Method and results

In this paper we develop and explore an approach to estimate dynamic models of activity generation on one-day travel-diary data. Dynamic models predict multi-day activity patterns of individuals taking into account dynamic needs as well as day-varying preferences and time-budgets. We formulate an ordered-logit model of dynamic activity-agenda-formation decisions and show how one-day observation probabilities can be derived from the model as a function of the model’s parameters and, with that, how parameters can be estimated using standard loglikelihood estimation. A scale parameter cannot be identified because information on within-person variability is lacking in one-day data. An application of the method to data from a national travel survey illustrates the method. A test on simulated data indicates that, given a pre-set scale, the parameters can be identified and that estimates are robust for a source of heterogeneity not captured in the model. This result indicates that dynamic activity-based models of the kind considered here can be estimated from data that are less costly to collect and that support the large sample sizes typically required for travel-demand modeling. We conclude therefore that the proposed approach opens up a way to develop large-scale dynamic activity-based models of travel demand.     

换热器熵产分析

在余热发电系统中,换热器直接将热源中的热量吸收传递到系统中,然后将从透平中出来的工质冷凝,其性能好坏直接影响了整个系统的效率。本文引入了无量纲熵产数Ns表示换热器的热力完善程度,并且通过熵产分析,揭示了换热器能耗产生的原因,确定了最佳的热力参数匹配,能够更好的完成节能目的。对于工业中余热发电项目的优化具有重要参考意义。     

第二代完整稳性衡准的验证与改进研究

国际海事组织正在研究制定第二代完整稳性衡准,根据已经提出的参数横摇和纯稳性丧失的第一层薄弱性衡准建议方案,对我国5艘客滚船、5艘集装箱船、5艘油船和5艘散货船进行实船验证,对第一层薄弱性衡准的建议方案的适用性和合理性,提出必要的改进意见和建议,以完善新的国际完整稳性衡准规则。     

变速恒频发电中混合励磁发电机模拟双向电压调节器的设计

介绍一种应用于变速恒频发电系统中,“模拟双向调节”的混合励磁发电机的电压调节模式.该调压器为双向调节模式,满足了混合励磁发电机变速条件下可靠输出稳定电压的要求.设计了稳压器,验证了性能.     

制氢技术的机动应用研究与改进设计

阐述了电解水制氢技术在机动车上的应用研究与改进设计,详细介绍了系统组成、工作原理、主要性能参数、载车综合控制技术的研究设计和关键技术的解决、电解新技术的研究及新工艺的应用等.机动制氢技术已成功应用于我国"神舟"号系列航天飞行试验和"嫦娥一号"绕月工程的气象保障业务,及时检测"发射、回收窗口"的信息,为航天飞行试验提供可靠的气象参数.     

通信中间件技术在新一代CTC系统中的应用

新一代CTC系统综合了计算机技术、网络通信技术和现代控制技术,采用智能化分散自律设计原则.整个系统通常存在多种硬件系统平台,如工业控制机、工作站、小型机等,不同的操作系统及不同的网络协议和体系结构,如何把这些系统集成起来并开发新的应用是一个非常现实而困难的问题.为此,从安全性、可靠性、扩充性、易管理性、可用性和可移植性等综合因素考虑,提出了采取中间件的方式完成跨平台通信机制.     

Generating complete all-day activity plans with genetic algorithms

Activity-based demand generation contructs complete all-day activity plans for each member of a population, and derives transportation demand from the fact that consecutive activities at different locations need to be connected by travel. Besides many other advantages, activity-based demand generation also fits well into the paradigm of multi-agent simulation, where each traveler is kept as an individual throughout the whole modeling process. In this paper, we present a new approach to the problem, which uses genetic algorithms (GA). Our GA keeps, for each member of the population, several instances of possible all-day activity plans in memory. Those plans are modified by mutation and crossover, while bad instances are eventually discarded. Any GA needs a fitness function to evaluate the performance of each instance. For all-day activity plans, it makes sense to use a utility function to obtain such a fitness. In consequence, a significant part of the paper is spent discussing such a utility function. In addition, the paper shows the performance of the algorithm to a few selected problems, including very busy and rather non-busy days.     

Effect of land use on decisions of shopping tour generation: A case study of three traditional neighborhoods in WA

This study investigates the relationship between land use and shopping tour generation using an activity-based shopping model that captures the effects of land use patterns on household decisions of shopping tour frequency, tour scheduling and mode choice. The model was calibrated using travel data collected in three traditional neighborhoods located in the Puget Sound region, WA, and shopping travel patterns across seven common household structures were analyzed. The results reveal that land use patterns have virtually no impact on overall shopping tour frequency. However, land use does seem to be associated with decisions about the type of shopping tours undertaken. For example, households with poorer accessibility tend to make fewer one-stop shopping tours, and are more likely to combine shoppingtrips with other trips to form multi-stop shopping tours as a means of compensating for locational deficiencies. Finally, we also found that traditional neighborhood residents who live closer to the neighborhood commercial street, and thus, have greater accessibility, are more inclined to use non-auto modes for one-stop shopping tours.