Measuring the impact of urban policies on transportation energy saving using a land use-transport model

Various projects all over the world are attempting to build smart cities in hopes of achieving energy-efficient and livable communities, but most of them are aiming to fulfill their goals technologically. However, the energy efficiency and livability of a city are affected by not only these technological factors but also urban structures that encompass residential areas, offices, transportation networks, and other facilities. Urban policies intervene in transportation and land-use conditions and thereby change how citizens consume energy and go about their daily lives as the actors in the urban system alter their behavior. This means that energy efficiency and quality of life share close ties. Assessments of urban policies thus need to consider the reactions of actors to the intervention.     

CFD performance prediction simulation for hull-form design of sailing boats

A new simulation method is developed for the design of sailing boats. A time-accurate, finite-volume method is combined with the equations of motion, and the hydrodynamic properties of sailing boats are predicted. The hull configuration is designed by a CAD system, and a boundary-fitted grid system is generated for the finite-volume method. Six components of forces and moments are derived by integrating surface pressure and tangential stress, and input into the equations of motion. The translational or rotational motions obtained are represented by the deformation of the grid system. This is repeated in a time-marching procedure. This system is applied to the prediction of both steady and unsteady sailing performance of boats. The degree of accuracy is examined, and two examples of performance simulation are presented.     

A new weather-routing system that accounts for ship stability based on a real-coded genetic algorithm

The operation schedule of an oceangoing vessel can be influenced by wave or wind disturbances, and is therefore weather routed. The weather-routing problem is considered to be a multimodal function problem. Therefore, in the present research, the real-coded genetic algorithm technique (an evolutionary calculation technique) is applied to globally search for the optimum route. Additionally, to avoid maritime accidents due to parametric rolling, this route optimization method takes into account the risk of parametric rolling as one of its objective functions. Numerical verification is carried out for three kinds of objective functions with different weight ratios between fuel efficiency and ship safety in parametric rolling. As a result, it is numerically confirmed that the relation between economics and ship safety is a trade-off, and the safer route is not necessarily the most economical. Considering its robustness, the proposed method appears to be a powerful practical tool by choosing the most appropriate weights for economics and ship safety.     

Finite-volume simulation method to predict the performance of a sailing boat

 A flow-simulation method was developed to predict the performance of a sailing boat in unsteady motion on a free surface. The method is based on the time-marching, finite-volume method and the moving grid technique, including consideration of the free surface and the deformation of the under-water shape of the boat due to its arbitrary motion. The equation of motion with six degrees of freedom is solved by the use of the fluid-dynamic forces and moments obtained from the flow simulation. The sailing conditions of the boat are virtually realized by combining the simulations of water-flow and the motion of the boat. The availability is demonstrated by calculations of the steady advancing, rolling, and maneuvering motions of International America's Cup Class (IACC) sailing boats. Received: December 25, 2001 / Accepted: March 26, 2002