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In a fully mechanized coal-mining face, the positioning and attitude of the shearer and scraper conveyor are inaccurate. To overcome this problem, a joint positioning and attitude solving method that considers the effect of an uneven floor is proposed. In addition, the real-time connection and coupling relationship between the two devices is analyzed. Two types of sensors, namely, the tilt sensor and strapdown inertial navigation system (SINS), are used to measure the shearer body pitch angle and the scraper conveyor shape, respectively. To improve the accuracy, two pieces of information are fused using the adaptive information fusion algorithm. It is observed that, using a marking strategy, the shearer body pitch angle can be reversely mapped to the real-time shape of the scraper conveyor. Then, a virtual-reality (VR) software that can visually simulate this entire operation process under different conditions is developed. Finally, experiments are conducted on a prototype experimental platform. The positioning error is found to be less than 0.38 times the middle trough length; moreover, no accumulated error is detected. This method can monitor the operation of the shearer and scraper conveyor in a highly dynamic and precise manner and provide strong technical support for safe and efficient operation of a fully mechanized coal-mining face.

This article proposes a cooperatively analytic solving method that calculates the chute posture in the bending section. The method maintains a good posture of the scraper conveyor during its bending process and solves the feeding trajectory of the shearer accurately and precisely. This method modifies and perfects the existing method to obtain the main parameters of the bending section, including the postures of the chutes and pin rails, and the corresponding extension lengths of the advancing units. A virtual-reality software that can visually simulate this entire operation process under different conditions is developed. Considering the gap between the driving wheel and the pin rails, the relationship between the shearer yaw angle and shearer working trajectory in the feeding stage is investigated for different body lengths. The angular relationship between the left and right driving wheels and the pin rails is also researched. Finally, the proposal is verified in experiments on a test prototype and on physical equipment. This analytic method provides a theoretical basis for the cooperative three-dimension localization of three machines in a fully mechanized coal-mining face, ensuring safe automatic production of the mining face.

According to the characteristics of cable and decoration materials, the typical fire scenes were built using the method of FDS large eddy simulation (LES)). The smoke movement, temperature change, visibility and CO distribution of different fire scenes were studied. The fire spreading and risk when the fire occurs in electric vehicle charging and swapping station (EVCSS) were analyzed, which provides an important technological support for effectively preventing fire and guiding evacuation in EVCSS.

On the basis of analyzing the composition of losses in high-efficient high-voltage asynchronous motors, the approaches of increasing the efficiency of the motors is investigated in this paper. The approaches concern with the improvement of material, winding, fan, magnetic groove and so on. By taking the economy and efficiency into account synthetically, the design of the YKK series induction motors is carried on, and it is realized by software simulation.

With the great demands for lifelong learning and popularization of higher education, modern distance education has developed significantly in recent years. Therefore, how to ensure its quality, drawn great concern of the academic circles both in China and over the world, has become a vital issue in its development. By collecting Chinese literatures of recent years, particularly from 2006-2007, this paper analyzes and summarizes research findings of Chinese scholars on the problems in distance education. The paper address the key elements of quality assurance and standards, quality view as well as some thoughts and approaches on improvement of distance education in order to explore the practical way for ensuring its quality. The Chinese literatures mainly come from journals of ?China's Distance Education?, ?Modern Distance Education?, and ?Adult Education?.

Two types of familiar DC power, switching power and integrated voltage regulator (IVR) power were chosen as study objects, the injection experiments and radiation experiments of LEMP on power circuits were studied and experimental results of injection and radiation were compared and discussed. The results show that injection method and radiation method are irrelevant, and not only injection effects but also radiation effects should be considered to estimate lightning effects.

The communication protocol is important for applying adjustable speed drive (ASD) systems to an industry network. This paper proposes a novel scheme of communication system for the ASD system based on Modbus protocol. The most remarkable advantage of the approach lies in the tradeoff between performance and economic cost for a power converter system. The overall system is built on master-slave structure and easy for interacting with other networks. An additional study on the cyclic redundancy check (CRC) in Modbus RTU is introduced to obtain the optimization design in the actual application and the optimization method in software design is also presented. The performance of the communication system obtained from experiment conducted on the 15 kW ASD system validates the effectiveness of the proposed design method.

Instantaneous energy balancing plays an important role in power electronics conversion. The unbalance of electromagnetic energy not only debases the system performance but also decreases the reliability and efficiency of the conversion. In this paper, instantaneous energy balancing problems in three-level neutral point clamped (NPC) converters are classified and discussed. Typical examples and their usual solutions of each kind of problems are expounded and compared. In the end of this paper, limitations and disadvantages of traditional methods are analyzed, and electromagnetic field method is summarized as the new trend to analyze electromagnetic energy transmission and exchange. The method using electromagnetic field theory is emphasized to be the better approach to solve the aforementioned energy balancing problems.

In this paper, the performances of two types of ESD simulators (ESS-200AX made in Noiseken and NSG435 made in Schaffner) are studied, and ESD immunity experiments of a single chip microcomputer (SCM) system are made. The experimental results show that the differences between two simulators yield inconsistent test results though they both comply with the IEC61000-4-2 ESD standard. Therefore, besides the ESD current waveform, the relevant IEC61000-4-2 ESD standard should specify the discharge current derivative, related electromagnetic field in detail, and give unified specifications for the construction and configuration of ESD simulators.