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121.
In this paper, we explore the diurnal dynamics of joint activity participation in a small city in Pennsylvania, USA, using behavioral data and an inventory of business establishments. We account for the variation caused by the collective impact of social, temporal and spatial choices of individuals to produce predicted space–time visualizations of activity participation. The focus is on how social contexts of an activity impact the temporal and spatial decisions regarding the activity locations and how this impact varies depending on activity types. A comparison across activity types and social interaction types is made among spatial patterns during a day. The CentreSIM dataset, which is a household-based activity diary survey collected in Centre County (Pennsylvania, USA) in 2003, provides very detailed social interaction information enabling the analysis of social, spatial and temporal aspects of activity participation. In this paper we use this information to develop a spatio-temporal interpolation method and demonstration based on kriging. In this way, we extract the dynamic social taxonomy of places from the behavioral information in the dataset and suggest how urban and transportation models can be informed from the dynamics of places by observing “what is taking place” (activities being pursued in the context of this paper) combined with “what exists” (business establishments) or “what is available” (businesses that are open). The method here can also be used to improve the design of urban environments (e.g., filling gaps in desired activity locations), manage specific places (e.g., extending the opening and closing times of businesses), study transportation policies that are sensitive to time of day (e.g., pricing of parking to discourage crowding and traffic congestion), and modeling of spatio-temporal decisions of social activities in travel demand models (e.g., to guide the development of model specification and representation of the space in which behavioral models are applied). 相似文献
122.
用模糊逻辑实现动力定位船舶的艏向寻优 总被引:1,自引:1,他引:0
由于各种环境因素随时间不断变化,船舶作为动力定位作业时,最优艏向也是不断变化的,所以艏向寻优是动力定位的关键技术之一,本文用模糊逻辑实现艏向寻优,其优点是,不依赖于环境要素的测量值和数学模型,寻优与控制相结合,反应快,准确程度高。 相似文献
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部分斜拉桥的动力性能分析 总被引:4,自引:0,他引:4
对一座塔梁固结、梁墩分设的部分斜拉桥进行动力性能研究。根据该桥特点 ,分析上、下部结构共同作用和混凝土弹性模量变化对部分斜拉桥动力特性的影响 ,并将分析结果与该桥静动载试验的结果作对比 ,从而得出研究部分斜拉桥动力特性时应综合考虑上下部结构共同作用 ,可以忽略弹性模量变化 (动弹性模量 )影响的结论。 相似文献
125.
This paper describes the development of an optimal design process for a steering column system and supporting system. A design
guide is proposed at the initial concept stage of the development process to obtain sufficient stiffness of the steering system
while reducing the idle vibration sensitivity of the system. Case studies on resonance isolation are summarized, where vibration
modes among the systems are separated by applying a vibration mode map at the initial stage of the design process. This study
also provides design guidelines for an optimal dynamic damper system using a CAE (computer aided engineering) analysis. The
damper FE (finite element) model is added to the vehicle model to analyze the relation between the frequency and the sensitivity
of the steering column system. This analysis methodology makes it possible to achieve target performance in the early design
stage and reduction of damper tuning activity after the proto car test stage. Through the proposed steering column system
development process, a lightweight vehicle with high stiffness is possible prior to the proto build stage. Furthermore, the
improved process is expected to contribute to reducing the overall development period and the number of proto car tests necessary
to achieve the desired steering system performance. 相似文献
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A link-node complementarity model and solution algorithm for dynamic user equilibria with exact flow propagations 总被引:2,自引:0,他引:2
Xuegang Ban Henry X. Liu Michael C. Ferris Bin Ran 《Transportation Research Part B: Methodological》2008,42(9):823-842
In this paper, we propose a link-node complementarity model for the basic deterministic dynamic user equilibrium (DUE) problem with single-user-class and fixed demands. The model complements link-path formulations that have been widely studied for dynamic user equilibria. Under various dynamic network constraints, especially the exact flow propagation constraints, we show that the continuous-time dynamic user equilibrium problem can be formulated as an infinite dimensional mixed complementarity model. The continuous-time model can be further discretized as a finite dimensional non-linear complementarity problem (NCP). The proposed discrete-time model captures the exact flow propagation constraints that were usually approximated in previous studies. By associating link inflow at the beginning of a time interval to travel times at the end of the interval, the resulting discrete-time model is predictive rather than reactive. The solution existence and compactness condition for the proposed model is established under mild assumptions. The model is solved by an iterative algorithm with a relaxed NCP solved at each iteration. Numerical examples are provided to illustrate the proposed model and solution approach. We particularly show why predictive DUE is preferable to reactive DUE from an algorithmic perspective. 相似文献
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