Stop frequency models, as one of the elements of activity based models, represent an important part of travel behavior. Unobserved heterogeneity across the travelers should be taken into consideration to prevent biase...Stop frequency models, as one of the elements of activity based models, represent an important part of travel behavior. Unobserved heterogeneity across the travelers should be taken into consideration to prevent biasedness and inconsistency in the estimated parameters in the stop frequency models. Additionally, previous studies on the stop frequency have mostly been done in larger metropolitan areas and less attention has been paid to the areas with less population. This study addresses these gaps by using 2012 travel data from a medium sized U.S. urban area using the work tour for the case study. Stop in the work tour were classified into three groups of outbound leg, work based subtour, and inbound leg of the commutes. Latent Class Poisson Regression Models were used to analyze the data. The results indicate the presence of heterogeneity across the commuters. Using latent class models significantly improves the predictive power of the models compared to regular one class Poisson regression models. In contrast to one class Poisson models, gender becomes insignificant in predicting the number of tours when unobserved heterogeneity is accounted for. The commuters are associated with increased stops on their work based subtour when the employment density of service-related occupations increases in their work zone, but employment density of retail employment does not significantly contribute to the stop making likelihood of the commuters. Additionally, an increase in the number of work tours was associated with fewer stops on the inbound leg of the commute. The results of this study suggest the consideration of unobserved heterogeneity in the stop frequency models and help transportation agencies and policy makers make better inferences from such models.展开更多
为解决建筑结构设计信息在工程的后续阶段信息重用和共享困难的问题,本文引入国际工业基础类IFC(Industry Foundation Classes)标准研究建筑结构施工图设计信息模型。通过分析钢筋混凝土结构施工图设计BIM(Building Information Model)...为解决建筑结构设计信息在工程的后续阶段信息重用和共享困难的问题,本文引入国际工业基础类IFC(Industry Foundation Classes)标准研究建筑结构施工图设计信息模型。通过分析钢筋混凝土结构施工图设计BIM(Building Information Model)数据需求,利用IFC的建筑结构信息模型描述方法和模型扩展机制,构建了建筑结构施工图设计的IFC扩展模型,并基于该模型开发了钢筋混凝土结构施工图设计原型系统。系统应用表明,施工图设计模型可自动转化为工程算量模型,进行工程算量统计和分析,实现设计信息的无损交换与充分共享,从而验证了建筑结构施工图IFC扩展模型的可行性。展开更多
文摘Stop frequency models, as one of the elements of activity based models, represent an important part of travel behavior. Unobserved heterogeneity across the travelers should be taken into consideration to prevent biasedness and inconsistency in the estimated parameters in the stop frequency models. Additionally, previous studies on the stop frequency have mostly been done in larger metropolitan areas and less attention has been paid to the areas with less population. This study addresses these gaps by using 2012 travel data from a medium sized U.S. urban area using the work tour for the case study. Stop in the work tour were classified into three groups of outbound leg, work based subtour, and inbound leg of the commutes. Latent Class Poisson Regression Models were used to analyze the data. The results indicate the presence of heterogeneity across the commuters. Using latent class models significantly improves the predictive power of the models compared to regular one class Poisson regression models. In contrast to one class Poisson models, gender becomes insignificant in predicting the number of tours when unobserved heterogeneity is accounted for. The commuters are associated with increased stops on their work based subtour when the employment density of service-related occupations increases in their work zone, but employment density of retail employment does not significantly contribute to the stop making likelihood of the commuters. Additionally, an increase in the number of work tours was associated with fewer stops on the inbound leg of the commute. The results of this study suggest the consideration of unobserved heterogeneity in the stop frequency models and help transportation agencies and policy makers make better inferences from such models.
文摘为解决建筑结构设计信息在工程的后续阶段信息重用和共享困难的问题,本文引入国际工业基础类IFC(Industry Foundation Classes)标准研究建筑结构施工图设计信息模型。通过分析钢筋混凝土结构施工图设计BIM(Building Information Model)数据需求,利用IFC的建筑结构信息模型描述方法和模型扩展机制,构建了建筑结构施工图设计的IFC扩展模型,并基于该模型开发了钢筋混凝土结构施工图设计原型系统。系统应用表明,施工图设计模型可自动转化为工程算量模型,进行工程算量统计和分析,实现设计信息的无损交换与充分共享,从而验证了建筑结构施工图IFC扩展模型的可行性。
