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941.
山区河流渠化枢纽布置模糊综合评判 总被引:3,自引:1,他引:2
山区河流渠化布置是较复杂的问题,涉及影响因子较多,其中大多具有不能定量模糊因素。运用模糊数学思想,把模糊评判引入到山区渠化枢纽布置选优中,对选优前各个方案进行模糊评判,以期提供一种分析问题的思路。 相似文献
942.
计算机配色中活性染料单位浓度K/S值研究 总被引:1,自引:0,他引:1
在计算机自动配色中,所用染料的单位浓度K/S值准确与否,直接影响配色精度。提出的单位浓度K/S值算法思想是,通过引进调整系数,根据不同浓度梯度对光谱数据进行合理的调整,使库贝尔卡-芒克函数与浓度具有更好的线性关系。在实例分析中,用3组活性染料按不同浓度梯度对纯棉织物进行染色,应用最优化方法确定光谱数据的调整系数,进而求解所用染料的单位浓度K/S值,最后由三刺激值匹配算法得出预测配方,并使用CIE1976(L^*,a^*,b^*)均匀颜色空间色差公式来衡量配色效果。实验证明,配色的预测结果能够较好地满足计算机配色的要求。 相似文献
943.
Effect of attitudes, habit and affective appraisal on mode choice: an application to university workers 总被引:1,自引:0,他引:1
Traditionally, car use and modal choice, in general, have been studied under the random utility framework, assuming that individuals
choose a particular mode based on their own socio-economic characteristics and the attributes describing the available options.
This approach has originated useful models which have been able to explain modal split. However, at the same time, it has
received critics because of its poor characterization of human behaviour and the weakness of its assumptions. Research has
suggested that socio-psychological factors could help to understand better the choice process. In this paper, attitudinal
theory and its link to human behaviour were used to select attitudes, habit and affective appraisals as explanatory variables.
They were measured using ad-hoc instruments, which were combined with a revealed preference questionnaire, in order to obtain
information about the traveller and the chosen mode. This instrument was applied to a sample extracted from staff members
of the University of Concepcion, Chile. Analyses of attitudinal variables showed that car use habit was positively correlated
to attitude and positive emotions towards car, implying that breaking the vicious circle of car use through persuasive techniques
might be difficult. Estimation of discrete choice models showed that attitudinal variables presented a significant contribution
to modal utility, and helped to improve both fitness and statistical significance. Results showed that choice can be influenced
by factors related to attitudes and affective appraisal, and that their study is necessary in order to achieve an effective
car use reduction.
相似文献
Alejandro TudelaEmail: |
944.
波形钢腹板组合箱梁自振特性与试验研究 总被引:3,自引:0,他引:3
为了精确计算波形钢腹板组合箱梁的振动频率,根据能量变分原理,推导了振动频率公式,得到了考虑剪切变形及剪力滞效应的各阶自振频率的解析解。对一试验波形钢腹板组合箱梁进行了动力测试,得到了实际自振频率,并与简单梁理论、本文理论公式与三维有限元模型的计算频率进行对比。结果表明:剪力滞效应及剪切变形对波形钢腹板组合箱梁的振动频率影响较大,考虑剪力滞及剪切变形影响后的波形钢腹板组合箱梁的振动频率有所降低,且降低程度随着计算频率阶次的增加而迅速增加,因而在波形钢腹板组合箱梁振动频率的计算中须计其影响。 相似文献
945.
A probabilistic framework for weather-based rerouting and delay estimations within an Airspace Planning model 总被引:1,自引:0,他引:1
Michael V. McCrea Hanif D. Sherali Antonio A. Trani 《Transportation Research Part C: Emerging Technologies》2008,16(4):410-431
In this paper, we develop a novel severe weather-modeling paradigm to be applied within the context of a large-scale Airspace Planning and collaborative decision-making model in order to reroute flights with respect to a specified probability threshold of encountering severe weather, subject to collision safety, airline equity, and sector workload considerations. This approach serves as an alternative to the current practice adopted by the Federal Aviation Administration (FAA) of adjusting flight routes in accordance with the guidelines specified in the National Playbook. Our innovative contributions in this paper include (a) the concept of “Probability-Nets” and the development of discretized representations of various weather phenomena that affect aviation operations; (b) the integration of readily accessible severe weather probabilities from existing weather forecast data provided by the National Weather Service; (c) the generation of flight plans that circumvent severe weather phenomena with specified probability threshold levels, and (d) a probabilistic delay assessment methodology for evaluating planned flight routes that might encounter potentially disruptive weather along its trajectory. Additionally, we conduct an economic benefit analysis using a k-means clustering mechanism in concert with our delay assessment methodology in order to evaluate delay costs and system disruptions associated with variations in probability-net refinement-based information. Computational results and insights are presented based on flight test cases derived from the Enhanced Traffic Management System data provided by the FAA and using weather scenarios derived from the Model Output Statistics forecast data provided by the National Weather Service. 相似文献
946.
集肤效应伴热技术在辽河油田的应用 总被引:3,自引:0,他引:3
针对辽河油田油稠、高凝油面积大、凝固点高,在集输过程中易凝、输送困难的特点,在集输过程中采用了集肤效应伴热的方法。集肤效应是一种新型的输液管伴热技术,伴热结构合理、热能利用率高、伴热温度可控、使用寿命长,是管道安全运行的最好措施。介绍了集肤效应国内外的应用情况,着重介绍了集肤效应的基本原理和在实际应用中的经济性对比,集肤效应发热部分和电源部分的基本结构,集肤效应伴热技术在辽河油田中的使用情况。 相似文献
947.
将三维时域CFD方法应用于计算和分析水管路消声器的声学性能.对于直通穿孔管消声器与横流穿孔管消声器,在不考虑水的流动时,传递损失的时域CFD方法计算结果与频域有限元法计算结果吻合很好.时域CFD方法进而被用于研究流速对穿孔管消声器消声特性的影响.计算结果表明,介质流动增大了消声器的传递损失,特别是在高频区域;消声器的传递损失随流速的增加而增大. 相似文献
948.
949.
Community severance occurs when transport infrastructure or motorised traffic divides space and people. Despite the growing awareness of its effects on the wellbeing of local communities, the problem is not usually assessed quantitatively or assigned a monetary value. This paper reviews existing practice and research on quantitative methods dealing with community severance. The problem is first decomposed into a series of questions, which are then used as a base to review the methods found in governmental guidance documents, technical reports, and academic studies. The paper ends with recommendations for the integration of severance issues into transport planning. 相似文献
950.
Work zones exist widely on urban arterials in the cities that are undergoing road construction or maintenance. However, the existing studies on arterial work zones are very limited, especially on the work zones at urban intersections, although they have a severe negative impact on the urban traffic system. For the first time, this study focuses on how work zones reduce intersection capacity. A type of widely observed work zone, the straddling work zone that straddles on a road segment and an intersection, is studied. A linear regression model and a multiplicative model suggested by Highway Capacity Manual are proposed respectively to determine the saturation flow rate of the signal intersection with the straddling work zone. The data of 22 straddling work zones are collected and used to evaluate the performances of the proposed models. The results display that the linear regression model outperforms the multiplicative model suggested by Highway Capacity Manual. The study also reveals that reducing approach (or exit) lanes and the mixture of motor vehicles and non‐motor vehicles (and pedestrians) can significantly decrease the capacity of the intersection with straddling work zone. Therefore, in setting a straddling work zone, workers should try to ensure that the intersection approach and exit are unobstructed and set a separation for non‐motors and pedestrians to avoid mixed traffic flow. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献