Nonlinear Auto-Companding Method for Behavioral Modeling of Switched-Current Circuits

A wavelet collocation method with nonlinear auto companding is proposed for behavioral modeling of switched current circuits.The companding function is automatically constructed according to the initial error distribution obtained through approximating the input output function of the SI circuit by conventional wavelet collocation method.In practical applications,the proposed method is a general purpose approach,by which both the small signal effect and the large signal effect are modeled in a unified formulation to ease the process of modeling and simulation.Compared with the published modeling approaches,the proposed nonlinear auto companding method works more efficiently not only in controlling the error distribution but also in reducing the modeling errors.To demonstrate the promising features of the proposed method,several SI circuits are employed as examples to be modeled and simulated.

Shape optimization of plate with static and dynamic constraints via virtual laminated element

The virtual laminated element method (VLEM) can resolve structural shap e optimization problems with a new method. According to the characteristics of V LEM , only some characterized layer thickness values need be defined as design v ariables instead of boundary node coordinates or some other parameters determini ng the system boundary. One of the important features of this method is that it is not necessary to regenerate the FE(finite element) grid during the optimizati on process so as to avoid optimization failures resulting from some distortion grid elements. Th e thickness distribution in thin plate optimization problems in other studies be fore is of stepped shape. However, in this paper, a continuous thickness distrib ution can be obtained after optimization using VLEM, and is more reasonable. Fur thermore, an approximate reanalysis method named ″behavior model technique″ ca n be used to reduce the amount of structural reanalysis. Some typical examples are offered to prove the effectiveness and practicality of the proposed method.

Modeling and Simulation of Heat Transfer through an Electric Wire

This paper illustrates the use of a general purpose differential equation （DE） solver called FlexPDE for the solution heat transfer problems in electric wire. FlexPDE uses the finite element method for the solution of boundary and initial value problems. A flexible input of the governing DE＇s and of material properties functions allows the simulation of non-linear variable behavior quickly and inexpensively. A modeling of temperature distribution in one-dimensional problem, a cross section of an electric wire was simulated. Comparison of those results obtained by FlexPDE with analytical and numerical solutions are done. The results compared well with those obtained from the analytical and numerical methods. The adaptability of the FlexPDE software for solving a variety of problem types was clearly demonstrated.

Kinetic Behavior of Aggregation-Exchange Growth Process with Catalyzed-Birth

We propose an aggregation model of a two-species system to mimic the growth of cities＇ population and assets, in which irreversible coagulation reactions and exchange reactions occur between any two aggregates of the same species, and the monomer-birth reactions of one species occur by the catalysis Of the other species. In the case with population-catalyzed birth of assets, the rate kernel of an asset aggregate Bκ of size k grows to become an aggregate Bκ＋1 through a monomer-birth catalyzed by a population aggregate Aj of size j is J（κ,j） = Jkjλ. And in mutually catalyzed birth model, the birth rate kernels of population and assets are H（k,j）=Hkjη and J（k,j） = Jkjλ, respectively. The kinetics of the system is investigated based on the mean-field theory. In the model of population-catalyzed birth of aseets, the long-time asymptotic behavior of the assets aggregate size distribution obeys the conventional or modified scaling form. In mutually catalyzed birth system, the asymptotic behaviors of population and assets obey the conventional scaling form in the case of η=λ =0, and they obey the modified scaling form in the case of η=0, λ=1. In the case of η = λ= 1, the total mass of population aggregates and that of asset aggregates both grow much faster than those in population-catalyzed birth of assets model, and they approaches to infinite values in finite time.

Factors Influencing on Drinking Water Source Selection in Rural Areas of the Bengal Region

The arsenic contamination of underground water is a serious problem in rural areas of the Bengal region, where the water pipeline supply is not equipped. Those, who suffer from the contamination are mainly in the poorest sector. In the region, the selection of drinking water sources is done by women. The local traditional custom of Parda may restrict women＇s behavior. In this paper, a quantitative way of evaluating women＇s psychological stress is proposed, and mechanisms of women＇s water selection are analyzed using behavioral model. Ultimately, the more acceptable ways of installing water facilities to local people in each village are discussed.

The Information Security of Digital Control Systems for Nuclear Power Plants

The NPP （nuclear power plant） being vital objects of an energy infrastructure must be protected against malicious actions affecting their safety, and cyber security plays a key part in attaining this goal. The paper considers, implemented by the authors within the project of advanced digital control system for NPP with the reactor VVER-1000, a system of unauthorized access protection, partially built up on the technology of AA （active audit） and expert system. The AA technology is based on response of the system on deviation of current signature of the automated process control system from stable state rather than on a certain signature of attack and relies on the estimation of the behavioral models of the particular digital control system. The advent of active audit reflects the current situation in the digital control systems where complex distributed platforms are used to construct automated process control system. The active audit allows one to make the digital control system functionally closed, provided that it is determinate. The methodology of the active audit does not give u external （barrier） and traditional （password, antivirus） methods of unauthorized access protection. These methods can be used when it is appropriate to achieve a required protection level.

A mesoscale model based on Monte-Carlo method for concrete fracture behavior study

An aggregate generation and packing algorithm based on Monte-Carlo method is developed to express the aggregate random distribution in cement concrete. A mesoscale model is proposed on the basis of the algorithm. In this model, the concrete con- sists of three parts, namely coarse aggregate, cement matrix and the interracial transition zone （ITZ） between them. To verify the proposed model, a three-point bending beam test was performed and a series of two-dimensional mesoscale concrete mod- els were generated for crack behavior investigation. The results indicate that the numerical model proposed in this study is helpful in modeling crack behavior of concrete, and that treating concrete as heterogeneous material is very important in frac- ture modeling.