Applied Mechanics and Materials Vols. 55-57

Abstract: In order to study generalized 3x+1 function C(z), we find the character of fixed points of C(z) at real axis by complex analytical analysis. Then we improve the solving algorithm of its fixed points. We proved that the integer fixed points of C(z) are 0 and -1 and the attract fixed points of C(z) are 0 and -1.2777. Popularized the result to complex plane, we prove that there is no fixed point of C(z) except real axis. We draw the fractal figures of C(z) by escape time algorithm to prove the result and give a conjecture from the fractal figures. The conjecture guess that the attract domain of C(z) is a connected domain which is connected with single point.

Abstract: LFMCW radar have a high range measuring accuracy in theory. But in practice, the picket fence effect of the FFT transform, making the range resolution and range accuracy in the same order of magnitude, can not meet the accuracy requirements for the near range measuring . Cascade FFT method is adopted to reduce frequency space of the main lobe of echo range spectrum on the FFT with increasing the less operation .The method can greatly improve the range precision of LFMCW Radar.

Abstract: In electromechanical products form design, there still exist problems such as CAD supporting incompletely and low-usage of existent excellent case form information, this paper proposed a comprehensive method of product form design, which integrated morphological matrix, BP network, Analytical Hierarchy Process (AHP), Gray Relating Analyze (GRA) and Genetic Algorithms. According to the heritability of product form features, this method deconstructed case product modeling components and form elements to obtain the form features, then the features and feature values of product form were represented by morphologic matrix, finally product form design scheme were combined with reasonable solutions. Grading method and AHP were used to quantify the modeling components feature, form elements and perceptual image vocabularies of case product, and a BP network model was trained for form scheme image prediction. This article constructed the genetic algorithm fitness function with the weighed grey relation grade to optimize the product form scheme based on customers’ requirements. VC++ was applied to develop the design software, the design of electric bicycle form scheme was taken to illustrate the application process of this method.

Abstract: In view of high-load density, abundant in wind power and solar energy resources and well-developed areas in the southeastern coastal areas of China, A great number of power system planning problems have emerged. This paper first analyzes the limitations of electric power supply with 10kV voltage level and the advantages of using 20 kV voltage level in distribution network, and then it introduces the status and disadvantages of regenerative energy power to be incorporated into the large grid along the southeast coast of China at present. Finally it is discussed that the advantages of establishing the power supply system based on 20kV power distribution network and Microgrid according to the new resources distribution and the existing problems of medium voltage power distribution in southeast China.

Abstract: With the growth of industry manufacturers and population, power quality becomes more and more important issue, and is attracting significant attention due to the increase in the number of sensitive loads. A distribution static compensator (DSTATCOM) is a voltage source inverter (VS1)-based power electronic device, which is usually used to compensate reactive power and sustain the system voltage in distribution power system. Compared with the traditional STATCOM, multilevel STATCOMs exhibit faster dynamic response, smaller volume, lower cost, and higher ratings. A multilevel inverter connected to an energy storage device can control both active and reactive power flow, providing more flexible and versatile power transmission operation. SPWM is actually a kind of multi-pulse trigger mode and used to trigger the switches in DSTATCOM.

Abstract: Static Synchronous Compensator (STATCOM) using the voltage source inverter (VSI) has been widely accepted as the current generation of the reactive power regulators of power system, improving the network steady-state and dynamic performances, regulates power factor, reduces losses and allows higher power flows in the exist line, assists in the post-fault recovery of transmission system. The cascade inverter not only can eliminate the bulky transformers compared with the conventional STATCOM, but also employ a sinusoid pulse width modular scheme: phase-shift. The use of the feedback linearization approach to design nonlinear controllers of power inverters is particularly interesting because it transforms a nonlinear system into a linear one in terms of its input–output relationship. Partial linearization may still be useful in some cases providing that the internal zero dynamics exhibit a proper transient performance.

Abstract: With the wide spread of cloud computing technologies, we assume that increasing amount of attentions will be given to the area of software evolution processes in the context of cloud computing environments. Some major problems we are here facing now include: What kind of process a software evolution model under the circumstances of cloud computing must possess What properties a software process must have as an attribute in order to effectively support the software evolution How to modeling a process in the context of software evolution While aiming to solve these mentioned problems, we focused our research on establishing a software evolution process model with independent functions as a component. In this article, the detailed discussion of our thoughts has been given and the in-depth analysis of our model is shown. Through a realistic case to which this model is applied, we concluded that our model provided the software evolution process with an effective support under the circumstances of cloud computing.

Abstract: While cloud computing related technologies are gaining increasing amount of popularities nowadays, we are focusing our resent research on the aspects of software evolution processes under the environments of cloud computing. During our pervious research, we have proposed SEPUCCC, a software evolution process prototype under the circumstancees of cloud computing. In this article, we are going to have a further disscussion on SEPUCCC by giving it’s in-depth performance analysis, by which the model’s abilities, the abilities to supporting the evolution process under the circumstances of cloud computing as well as reducing the cost of process improvemnet, was demomstrated.