Residential location,vehicle ownership and travel in Asia: a comparative analysis of Kei-Han-Shin and Kuala Lumpur metropolitan areas

The study examines the relationships between residential location, vehicle ownership and mobility in two metropolitan areas of Asia, Kei-Han-Shin area of Japan and Kuala Lumpur area of Malaysia. It shows that, behind apparent similarities of household auto ownership and travel time expenditure per household member, there are many causal relationships that are distinct between the areas. The similarities and differences between the two areas point to the conjecture that the evolution of a metropolitan area may be unique and path dependent, being heavily influenced by the history and culture of the locale, spatial and geographical constraints, and historical progression in infrastructure development.

A porous cell method for the simulation of fluid-solid interactions

There are many ways of describing a solid,porous or fluid region of the computational domain when solving the Navier-Stokes equations(NSE)for flow motions.Amongst these the porous cell method is one of the most flexible approaches.In this method,a parameter is defined as a ratio of the volume open to water and air in a calculation cell to its cell volume.In the calculation,the same numerical procedure is applied to every cell and no explicit boundary conditions are needed at solid boundaries.The method is used to simulate flow through porous media,around solid bodies and over a moving seabed.The results compare well with experimental data and other numerical results.In our future work the porous cell method will be applied to more complex fluid-solid interaction situations.     

船舶十字轴万向节轴系受力分析

船舶十字轴万向节轴系的轴承由于十字轴万向节的影响,其受力情况复杂。文章简要分析十字轴万向节特殊的力学特性和速度特性,并分析十字轴万向节的受力情况。在此基础上运用平衡方程、三弯矩方程、MATLAB软件和EXCEL软件计算船舶十字轴万向节轴系上各个轴承在各种情况下的径向负荷。最后,简要分析十字轴万向节轴向力计算方法及其对轴系轴向力轴承的影响。为十字轴万向节轴系设计、建造和维修提供理论依据。     

A comprehensive dwelling unit choice model accommodating psychological constructs within a search strategy for consideration set formation

This study adopts a dwelling unit level of analysis and considers a probabilistic choice set generation approach for residential choice modeling. In doing so, we accommodate the fact that housing choices involve both characteristics of the dwelling unit and its location, while also mimicking the search process that underlies housing decisions. In particular, we model a complete range of dwelling unit choices that include tenure type (rent or own), housing type (single family detached, single family attached, or apartment complex), number of bedrooms, number of bathrooms, number of storeys (one or multiple), square footage of the house, lot size, housing costs, density of residential neighborhood, and commute distance. Bhat’s (2015) generalized heterogeneous data model (GHDM) system is used to accommodate the different types of dependent outcomes associated with housing choices, while capturing jointness caused by unobserved factors. The proposed analytic framework is applied to study housing choices using data derived from the 2009 American Housing Survey (AHS), sponsored by the Department of Housing and Urban Development (HUD) and conducted by the U.S. Census Bureau. The results confirm the jointness in housing choices, and indicate the superiority of a choice set formation model relative to a model that assumes the availability of all dwelling unit alternatives in the choice set.     

一类分数阶非线性微分方程组的显式算法

讨论了一类分数阶微分方程组的一种数值算法,根据Caputo导数的性质,将分数阶微分方程组转化为Volterra积分方程组,再利用求解普通积分方程的Adams技巧,建立了分数阶微分方程组的一种显式数值算法,证明了该算法的收敛性与稳定性,并给出了数值仿真实例,证实了算法的有效性.     

Profile-speed data-based models to estimate operating speeds for urban residential streets with a 30 km/h speed limit

A speed limit of 30 kilometres per hour (km/h) has been widely introduced for urban residential streets to ensure traffic safety and allow these streets to fulfil other intended functions. However, excessive speeds on these roads are very common, causing traffic safety problems and threatening the liveability of neighbourhoods. An effective and active way to deal with speeding is the application of a performance-based design approach, as mentioned in previous research. In a performance-based design approach, street geometrics and roadside elements are selected based on their influence on the desired driving speeds. The relationship between driving speeds and street features therefore needs to be determined. Although several studies have developed operating speed models for urban streets, all of these models were calibrated based on data for streets with speed limits of more than 30 km/h. The present research is designed to investigate the influence of various roadway and roadside characteristics on operating speeds on urban tangent street sections with a 30 km/h speed limit using profile-speed data. A simultaneous equation regression with a three-stage-least-square (3SLS) estimator was used for the modelling effort. The driving speed models developed in this study incorporate several street design factors, which provide helpful information for urban planners and street designers to cope with speeding issues on residential streets.     

Bayesian statistical data assimilation for ecosystem models using Markov Chain Monte Carlo

This study considers advanced statistical approaches for sequential data assimilation. These are explored in the context of nowcasting and forecasting using nonlinear differential equation based marine ecosystem models assimilating sparse and noisy non-Gaussian multivariate observations. The statistical framework uses a state space model with the goal of estimating the time evolving probability distribution of the ecosystem state. Assimilation of observations relies on stochastic dynamic prediction and Bayesian principles. In this study, a new sequential data assimilation approach is introduced based on Markov Chain Monte Carlo (MCMC). The ecosystem state is represented by an ensemble, or sample, from which distributional properties, or summary statistical measures, can be derived. The Metropolis-Hastings based MCMC approach is compared and contrasted with two other sequential data assimilation approaches: sequential importance resampling, and the (approximate) ensemble Kalman filter (including computational comparisons). A simple illustrative application is provided based on a 0-D nonlinear plankton ecosystem model with multivariate non-Gaussian observations of the ecosystem state from a coastal ocean observatory. The MCMC approach is shown to be straightforward to implement and to effectively characterize the non-Gaussian ecosystem state in both nowcast and forecast experiments. Results are reported which illustrate how non-Gaussian information originates, and how it can be used to characterize ecosystem properties.     

Volterra型积分微分方程边值问题

利用上下解方法研究了Ｖｏｌｔｅｒｒａ型积分微分方程ｕ″＝ｆ（ｔ，ｕ，ｕ＇，Ｔｕ），ｕ（０）＝Ａ，     

线性代数方程组正交化列处理法

给出对任意的n×m阶相容性或不相容性线性代数方程组均有效的一种新的迭代算法 .证明了算法求解过程 .在经过m次迭代后 ,必然求得该方程组的理论上精确的解或最小二乘解 .分析了该算法的计算复杂度、数值稳定性和内在并行性     

关于连续正整数Diophantine方程的正整数解

连续正整数Diophantine方程xn+(x+1)n+…+(x+h)n=(x+h+1)n的正整数解问题,是一个迄今为止尚未彻底解决的数论难题。目前已知的结果是:①当6≤n≤33时;②当n>3且为奇数时;③当34≤n≤200且为偶数时,该方程均无正整数解。采用多种素数模筛法证明了:当200相似文献