In this review lecture the author will explain the principlesand practical methods of numerical weather prediction (NWP) and climate change prediction together with brief histories of NWP and development of climate models both in the world and in Japan. Since climate modeling requires vast amount of computer resources, climate model research in Japan was difficult until the 1980's and therefore the Japanese climate research community is rather young and small. Now the community is going to have a world biggest computer the Earth Simulator. Research strategy for more accurate climate modeling by use of the Earth Simulator is briefly disscussed especially in the context of global warming prediction.
Since earthquake ground motions involve various intrinsic and epistemic uncertainties, it is difficult even with the present knowledge to predict forthcoming events at a specific site in a reasonably accurate way. It is therefore desirable to develop a robust structural design method taking into account these uncertainties even partially. Critical excitation or worst-case analysis approaches are making remarkable progress recently and seem to be promising as a candidate to overcome such difficulties. In this paper, the power (area of power spectral density function) and the intensity (magnitude of power spectral density function) are fixed and the critical excitation is found under these restrictions. A design problem for restricted variable design earthquakes is formulated as a min-max problem which is expected to lead to the maximum global performance design for variable critical excitations. The elastic-plastic response characteristics of the building models designed by the present method are revealed for a broader class of excitations and code-specified design earthquakes.
Process asymmetry often gives rise to difficulties in process modeling and control. In this work a general modeling framework is proposed, which can effectively trade-off positive and negative process dynamics. It can also make the consideration of process asymmetry with small modeling effort. The simulation results obtained demonstrate that control system performances can be improved substantially.
Implicit numerical algorithm using return-mapping method has been proven to provide an excellent performance when integrating a nonlinear isotropic elastoplasticity; i.e., a pressure-dependent model, in particular, where only a few scalar equations are required to formulate whole governing equations (Aravas, 1987). The simplicity lies in the fact that return directions to yield surface are coaxial with updated stresses in principle stress space. Accordingly, an explicit form of a consistent tangent operator in regard to a modified Cam-clay was derived by Borja et al. (1990), giving by-passed steps needed for evaluating a costly inversion of material stiffness tensor. However, the similar procedure is not conveniently applicable to an anisotropic model mainly because return directions to anisotropic yield surface are not coaxial with updated state of stresses. Luccioni et al. (2000) employed a return-mapping technique to an anisotropic Bear-Clay model and concluded that the formulation of governing equations under a return-mapping scheme is complicated and relatively cumbersome due to the complexity of anisotropy; therefore, the method loses a performance and appears impractical to initial boundary value problems. In this study, a return-mapping regularization applicable to anisotropic models was developed following a typical procedure but a newly-developed process corresponding to invariant-based tensor basis was applied to solve a concerned limitation. An implementation of implicit finite element method and numerical illustration were presented to demonstrate a computational performance under the proposed procedure. The performance of the proposed procedure is evaluated through numerical simulations of compression test under plane strain conditions. The resulting solutions can reach a convergence with considerably accuracy even by a relatively large strain.