An Application of Dynamic Structure Model to SoilCorrosion Research

Soil corrosion is a complex system which is difficult to be simulated with mathematicalmodels. Taking the mountainous areas in western henan Province as an example, this paper describesthe application of dynamic structure model to soil corrosion analysis. The primary component factors ofthe soil corrosion system and the causality of the factors are determined in this paper. The interactiverelations of the systematic variables is established with delphi method. The dynamic structure modelis selected to make the forecast of the soil corrosion system, the analysis of sensitivity of the variablesand the analysis of the system control.

Practice on Gravity-1 Rocket Dynamic Characteristics Design

Since the Dongfeng-2 missile, full-vehicle modal testing has been established as an indispensable part of the development and testing of rocket and missile models. However, as rockets have been developed larger, the cost and duration of such tests have significantly increased, magnifying their impact on model development. This article follows the process of the modal testing practice of the Gravity-1 rocket, reviewing and summarizing the design process of the rocket's dynamic characteristics. Initially, the article introduces common modeling techniques for launch rockets, including the mass-beam model and the hybrid element model. It then discusses the relationship between the structural dynamics model of the launch rocket and modal testing, aiming to reduce testing costs through refined structural dynamics modeling methods. Subsequently, the article describes the dynamic characteristics design process of the Gravity-1 carrier rocket, categorizes structural parameters, and studies how the selection of structural parameters affects the predicted dynamic characteristics of the rocket. Finally, it elaborates on the design of the modal testing scheme and the dynamic characteristics design based on the test data.

Modelling the Term Structure of Hong Kong Inter-Bank Offered Rates （HIBOR）

Different single-factor models are used to estimate the term structure of Hong Kong Inter-Bank Offered Rates （HIBOR）. These models use stochastic differential equations which effectively reflect market characteristics of short- and long-term interest rates, such as capability of mean reversion and interest rate level fluctuation. For the period from 2005 to early 2007, the economy of Hong Kong had been relatively stable with pretty low volatilities in interest rate. However, starting from 2008 to beginning of 2012, the Hong Kong and the world economies had been steering from relatively stable to fluctuations, the 2008 financial tsunami initiated by the U,S. had been causing financial instability globally. With the U.S： government taking quantitative easing monetary policy, U.S. interest rates fluctuated and submerged rapidly. Volatility of HIBOR was extremely sensitive to fluctuation of U.S. interest rates, since Hong Kong dollar exchange rate has been pegged with U.S. dollar. In short, during the period of early 2008 to early 2012, volatility of short-term interest rate was extremely sensitive. Obviously, the term structure of interest rate for these two periods had made major shift, combining the two periods would lead to unfavorable econometric results.

Exergy and ecological modelling of lake environment

The thermodynamic theories and ecological theories can be integrated effectively by exergy(biogeochemical energy of the system) to study the environmental problems of the lakes and reservoirs. In this paper, the applications of exergy in the ecological modelling of lake environment were reviewed. Results showed that exergy can be used as a goal function to estimate the parameters of the ecological model for lakes and reservoirs and to develop the structural dynamic models accounting for the changes in lake ecosystems, and as an ecological indicators for the development and evolution of lake ecosystems.

ACG-TypeMethod for InverseQuadratic Eigenvalue Problems in Model Updating of Structural Dynamics

In this paper we first present a CG-type method for inverse eigenvalue problem of constructing real and symmetric matrices M,D and K for the quadratic pencil Q(λ)=λ^(2)M+λD+K,so that Q(λ)has a prescribed subset of eigenvalues and eigenvectors.This method can determine the solvability of the inverse eigenvalue problem automatically.We then consider the least squares model for updating a quadratic pencil Q(λ).More precisely,we update the model coefficient matrices M,C and K so that(i)the updated model reproduces the measured data,(ii)the symmetry of the original model is preserved,and(iii)the difference between the analytical triplet(M,D,K)and the updated triplet(M_(new),D_(new),K_(new))is minimized.In this paper a computationally efficient method is provided for such model updating and numerical examples are given to illustrate the effectiveness of the proposed method.