Understanding the process of activity scheduling is a critical pre-requisite to an understanding of changes in travel behavior. To examine this process, a computerized survey instrument was developed to collect household activity scheduling data. The instrument is unique in that it records the evolution of activity schedules from intentions to final outcomes for a weekly period. This paper summarizes an investigation of the structure of activity/travel patterns based on data collected from a pilot study of the instrument. The term “structure” refers to the sequence by which various activities enter one’s daily activity scheduling process. Results of the empirical analyses show that activities of shorter duration were more likely to be opportunistically inserted in a schedule already anchored by their longer duration counterparts. Additionally, analysis of travel patterns reveals that many trip-chains were formed opportunistically. Travel time required to reach an activity was positively related to the scheduling horizon for the activity, with more distant stops being planned earlier than closer locations. 相似文献
Shipbuilding industries have started to employ 3D CAD systems to integrate all design and production processes by achieving seamless data transfer and data sharing. The emerging 3D CAD system brings a considerable change in FE analysis field. The availability of 3D geometry increased the recognition of the need for developing automatic FE modeling system consequently.
However, general automatic mesh algorithms developed by academic research field have a limitation. The difficulty in satisfying lots of line constraints and the absence of proper idealization of 3D geometry entities defined in CAD system hinders directly employing the general mesh algorithms.
In this research, an automatic FE modeling system has been developed for cargo hold FE modeling and whole ship FE modeling. The basic concept of the algorithm is to decompose surfaces using stiffener lines into subregions and generate mesh using a rule established based on FE modeling practice of ship structure. Since the decomposed subregions take simple polygon, they can be easily transformed into elements by decomposing the polygon according to the rule defined considering the shape of the polygon and mesh seed on its perimeter. The algorithm is also designed to treat appropriate geometry idealizations for bracket-type surface and stiffener connections. The idealization process is also completely customized based on FE modeling practice. The validity of the developed system is verified through illustrative examples. 相似文献
Trip chaining is a phenomenon that we know exists but rarely investigate. This could be attributed to either the difficulty
in defining trip chains, extracting such information from travel diary surveys, the difficulty in analysing all the possible
trip chain types, or all of the above. Household travel diary surveys provide a wealth of information on the travel patterns
of individuals and households. Since such surveys collect all information related to travel undertaken, in theory it should
be possible to extract trip-chaining characteristics of travel from them. Due to the difficulty in establishing and analysing
all of the possible trip chain types, the majority of research on trip chaining has appeared to focus on work travel only.
However, work related travel in many cities does not represent the majority of activities undertaken and, for some age groups,
does not represent any travel at all. This paper begins by reviewing existing research in the field of trip chaining. In particular,
investigations into the definitions of trip chaining, the defined typologies of trip chains and the research questions that
have been addressed are explored. This review of previous research into trip chaining facilitates the following tasks: the
identification of the most useful questions to be addressed by this research; defining trip chaining and associated typologies
and defining data structures to extract trip chaining information from the household travel surveys conducted in metropolitan
Adelaide, South Australia. The definition and typology developed in our research was then used to extract trip-chaining information
from the household travel diary survey (MAHTS99) conducted in Adelaide in 1999. The extracted trip chaining information was
then used to investigate trip-chaining behaviour by households. The paper reports the results of this analysis and concludes
with a summary of the findings and recommendations for further investigations. 相似文献