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High voltage SF6 circuit breaker must meet the breaking requirement for large short-circuit current, and ensure absence of breakdown after breaking small current. A 126kV high voltage SF6 circuit breaker was used as the research object in this paper. Based on the calculation results of non-equilibrium arc plasma material parameters, the distribution of pressure, temperature and density were calculated...
This paper presents a numerical model for simulating the breakdown performance of SF6-N2 and SF6-CF4 mixtures gas. Firstly, the ionization and attachment coefficients of mixtures were obtained by solving Boltzmann equation at different mixing ratio and 300K. All these parameters were applied on the fluid model to investigate the mechanism of electron number density varies along with time and space...
In cognitive radio (CR), spectrum sensing is a critical task to effectively detect the spectrum holes. Through dynamically accessing such idle spectrum, CR can improve spectrum utilization and provide broad wireless band for wireless services. There are two types of spectrum sensing algorithms for CR, which are cooperative and noncooperative spectrum sensing. Noncooperative spectrum sensing is easier...
In cognitive radio networks (CRNs), the spectrum utilization can be dramatically improved with the secondary users (SUs) accessing the unoccupied licensed channels opportunistically. However, how to fully utilize the spectrum holes to meet the quality of service requirements of SUs is still an open issue. In this paper, we focus on multi-user, multi-channel case, and analyze the stable channel state...
Vehicle scheduling of urban distribution is an important element of the logistics center's operation. The total scheduling cost is not only influenced by the satisfaction of customer service time window and the effective utilization of vehicle capacity, but also is closely related to the traffic flow, road capacity, vehicle saturation degree of intersection, traffic lights and road rules in actual...
Accurate modeling of Electroencephalography (EEG) signals is an important problem in clinical diagnosis of brain diseases. The method using support vectors machine (SVM) based on the structure risk minimization provides us an effective way of learning machine. But solving the quadratic programming problem for training SVM becomes a bottle-neck of using SVM because of the long time of SVM training...
Consider a master/slave scheme in the coordinated motion control for carrying a rigid body object by two robot arms, which one robot is called the leader and the other is called the follower. The problem is when the leader's motion leads the follower to a singular region, or the leader's motion requires the follower to avoid its joint limit or obstacle, the task cannot be accomplished due to the less...
When circuit breaker repeatedly breaks small capacitive current of compensation equipments,serious burning loss phenomenon is placed on the surface of static arc contact, which will lead to changing of contact shape. It may finally result in electric field distortion and adversely affect dielectric recovery characteristic. The mathematical models of electric field and flow field have been established...
As a important mechanical parameters for the vacuum circuit breaker, the contact bounce affects the electrical life of arc chamber. First, the mathematical model of contact bounce are established, the characteristics curve of contact bounce is obtained according to the mathematic model by using MATLAB. Secondly, the harm of contact bounce and the influence factors of contact bounce are analyzed. Finally,...
Laminar natural convection arising from horizontal rectangle cylinder to its concentric cylindrical enclosure is numerically studied. The Rayleigh number is varied in the range of 103≤Ra≤106. According to the form of isotherms and the streamline patterns, the basic features of flow and heat transfer for four rectangle cylinders with different aspect ratios are reported. And the local and average Nusselt...
The ranking interval number method is adopted for chemical oxygen demand production coefficient forecasting. It could be added to the fuzzy Bayes analysis model. The forecasting model is present. It could make Bayes risk decision making more practical. Financial factor of dyeing enterprise combining with COD experimental setting is adopted for COD forecasting. The standard and extension chemical oxygen...
This investigation focuses on the numerical analysis of the dynamic behavior of a high-pressure safety valve. A three-dimensional compressible flow model and the RNG k - ?? turbulence model are used to obtain the flow and thermal fields. The equations that govern the flow and heat transfer processes are solved by the finite volume method. The dynamic behavior has been presented by analyzing the complex...
The research of multi-product manufacturing scheduling under the circumstances of multi-orders is not profound so far, therefore, this paper proposed a new multi-objective optimization model which was base on orders. The objectives of this model include maximization of profit and balanced production. In order to realize balanced production, we use a method which could minimize various resource consumption...
Using formal method is an effective methodology for modeling and verifying software system. Category theory provides a kind of common language, tool, thinking method and study means for other mathematics subjects, in which a sketch as a formal structure is a specification based on graphs. This paper gives a linear sketch for the Web navigation behavior, and constructs a formal model based on the category...
Robust L2 control is a controller with fixed structure and parameter. It also satisfies performance requirement under the bad uncertainty, which is a salient features for Robust L2 control. The mathematical model of Brushless Direct Circuit Linear Motor (BLDCLM) is nonlinear, so introduction nonlinear control can restrain disturbance and track the input signal accurately. Then according to positioning...
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