Advanced Materials Research Vols. 546-547

Abstract: The article introduces the design of the half-bridge switching and regulated power supply system which is based on PWM. The design mainly consists of regulated power supply’s structure of basic hardware circuit, its working principles and the process of modeling simulation and software design. The control circuit controls SG3525 chip to output PWM wave through the Microprocessor Control Unit (MCU) of AT89C51 and drives IGBT through the chip of EXB841 as well. The MCU is also used to realize the keyboard process and controls of the pulse width and frequency. Taking advantage of Simulink (dynamic simulation Toolbox) and SimPowerSysterm (power simulation Toolbox) of MATLAB, it simulates the designed regulated power supply. According to the simulation result of this design, the system has high stability and good output waveform. The operation of the design is simple and clear with less software operation and higher speed.

Abstract: The power load forecasting is the core component of the early warning system for fuel storage margin in power system and an important guarantee to the early warning function to achieve. In this paper, one province's 2008 load data is chosen to forecast the electricity consumption in 2009. Firstly the two forecasting models of polynomial trend extrapolation and ARIMA are established, and then the combined model of them is used to forecast, that is, the final result is equal to the sum of the trend value by polynomial extrapolation and the non-trend D-value’s forecasting result by ARIMA. The results indicate that the combination forecasting make the forecast accuracy significantly improved and ensure the effective operation of the early warning system.

Abstract: HVDC transmission (HVDC) is very sensitive to the strength of the AC system especially in fault, may cause a DC power transmission interrupt. Based on the PSCAD simulation software built the HVDC transmission model and SVC-HDVC HVDC transmission model as an example. Made an analysis and research for the influence to the DC exchange station when the exchange side make fault.

Abstract: Successful applications of the ERM depend on accurate simulation models. Firstly, we built up a model on the 5000 volts ERM with ansoft. Then we measured motion trajectories of the ERM prototype respectively by means of a piezoelectric acceleration transducer, a magnetic grating displacement transducer and a linear displacement sensor. Based on the comparative analysis of the results from simulation and measurement, we concluded that the simulation model was reliable on one hand, and on the other hand by means of a linear displacement sensor along with a magnetic grating counterpart, we could obtain accurate motion trajectories with a relative error less than 5%.

Abstract: Radio frequencies explosive magnetic flux compression generator, which use capacitors as the load, is a kind of maneuverable device for generating and radiating electromagnetic pulse. From the equivalent circuit principle analysis on explosive magnetic frequency generator, the influence of capacitance variation discipline on operation current and oscillation frequency is analyzed based on the further analysis of the influence and comparison of inductance variation discipline on time and frequency characteristic of operation current. Then the center frequency of operation current under the circumstance of adopting different capacitance value when dynamic inductance linear changing has been calculated by software programming.

Abstract: Aiming at the limitation of Open Grid Services Architecture-Data Access and Integration middleware only face to JDBC, learning from the design ideas of OGSA-DAI, based on XML and web service, this paper proposes a middleware named XML Transformation-Data Access and Integration using ADO.NET. It analyzes the component structure of the middleware, the interaction of the workflow and the underlying data resources as well as the execution process of the workflow. It describes the conversion process between XML and database. Test result shows that the middleware gets good versatility and easy scalability in heterogeneous data access.

Abstract: To resist algebraic attacks, a high algebraic immunity is now an important criteria for Boolean functions used in stream ciphers. In recent years, several constructions of Boolean functions with maximum algebraic immunity (MAI) have been investigated. In this survey paper, we review the recent constructions of Boolean functions with MAI, and classify those into several different classes by the construction idea. Further, we also present some results and developments of these methods, including some results of the authors.

Abstract: As the improvement of the requirements of Military Information Security, information hiding technology will become an important method in defence of information security. Based on the basic definition and principles of information hiding technology, DCT transfer based on MATLAB is introduced to analyze the application of image hiding technology in military field. According to the simulation results, the need of information hiding technology in Military Information Security is analyzed. On the basis of the need, the application scope of information hiding technology in Military Information Security is illuminated and some issues that should be concerned in application are given at the end.

Abstract: Through the analysis on e-government business characteristics and its application model, this article proposes that e-government workflow model is the core technology of e-government applications. Hence this paper conducts further study respectively on design state and running state of e-government workflow model. In the design of state, it gives some related definitions about e-government workflow model, such as link, link relationship, receiver, condition, action, event and relations between them. Then gives rise to e- workflow modeling ideas and design framework. In the running state, it focuses on the problems to be solved (deadlock problem) in the actual operation of workflow system. It puts forward related algorithm and data related entities and then discusses about the design of the workflow engine idea.

Abstract: A new blind digital watermarking algorithm based on the chain code is proposed. The chain code is obtained by the characteristics of the original image -the edge contour. The feather can reflect the overall correlation of the vector image, and chain code expression can significantly reduce the boundary representation of the amount of data required. For the watermarking embedding, the original vector image is divided into sub-block images, and two bits of the watermarking information are embedded into sub-block images repeatedly by quantization. For watermarking extracting, the majority decision method is employed to determine the size of the extracted watermark. Experimental results show that the image quality is not significantly lowered after watermarking. The algorithm can resist the basic conventional attacks and has good robustness on the shear attacks.