Applied Mechanics and Materials Vols. 347-350

Abstract: The present researches of the MIMO theory only proved that channel capacity (CC) could be increased on the setting mathematical model in base-band by the space division multiplex (SDM) principle. But the reasonable physical model matching to that mathematical model has not been given by those researches, resulting in that the SDM could not be realized in MIMO system. So that the CC formula of MIMO system deduced by that mathematical model could not be realized physically. The infeasibility of MIMO system would be discussed in the paper in the aspects of physical characteristic of antenna, radio beam patterns of many kinds of antenna array, the un-reasonability of the MIMO physical model, the experiments of MIMO, and etc.

Abstract: In reality, wireless communication channels are designed to serve for multiple users while multipath propagation interference (MPI) and other problems are deteriorating the quality of service, especially when modern wireless communication demands higher data rate giving that less and less radio spectrum resources are available. Compared to conventional techniques trying to solve the related problems, smart antenna (SA) may have shed new light on the solutions of these issues. The forming of broadcast beam of SA is studied in this paper. Firstly, the mathematical formulas for the forming of directional broadcast beam by the method of baseband-amplitude-weighting are derived, according to which the corresponding circuit diagram is given. Then the forming method for broadcast beam for SA by combining several directional radio beams is presented. Moreover, the computer simulation results of SA with 6 array elements are provided to demonstrate the accuracy and achievability of this beam-forming method.

Abstract: Modulation principle of dual-polarization quadratu-re phase shift keying signal and polarization-switched QPSK signal are demonstrated and advantages of PS-QPSK are proved in theoretically. A novel modulation scheme of PS-RZ-QPSK signal is proposed in this paper. The scheme reduces transmitter cost by less use of Mach-Zehnder modulator, but also presents similar performance as traditional structure for PS-RZ-QPSK. The simulate result indicates PS-RZ-QPSK can achieve a better transmission performance than DP-RZ-QPSK at the same bit rate (84Gb/s) and baud rate (28GBd), and proves showing the feasibility of novel modulation scheme.

Abstract: As a very important part of Link-16, Joint Tactical Information Distribution System (JTIDS) has a good performance. In this paper, the primary technologies of JTIDS are presented and their Transmission performance are simulated and analyzed. And in the different conditions, the bit error rate simulation is tested based on the rationale of JTIDS. In the end of this paper, anti-jamming ability of JTIDS is simulated and the results show that JTIDS has high performance of anti-jamming.

Abstract: Medium logic completely reflects both the contrary relation and the contradictory relation. This paper introduces fuzzy privative and opposition privative in traditional knowledge representation. It takes a power transmission and distribution program for example, adopts a ratio function of distance to define the fuzzy set's member functions. Moreover, one confirmed method is presented to define the value as well as the threshold value in fuzzy production rules.Finally it discusses fuzzy knowledge reasoning by a specific example.

Abstract: With the extensive use of wind power, how to predict wind power effectively, to ensure the security, stability and economic operation of grid-connected wind power becomes a serious problem for the electronic companies. Based on the analysis about the status of wind power forecasting and application, the article designs a set of wind power forecasting and application system aimed at the security, stability of grid-connected wind system, which is described from the ideas of construction, software architecture, and development of hardware.

Abstract: According to the characteristics of PV power station, how to present a new intelligent surveillance and control system of PV power station, which collects the operating parameters at real-time and control the running status of the PV power station through wireless networks and the Internet, to guarantee the security, stability and economic operation of grid-connected PV system, becomes a problem which electric power enterprises have to be solved urgently. Based on the analysis of several remote monitoring technology projects which are general practical in PV system, the article designs a set of photovoltaic power plant monitoring system aimed at the security, stability of grid-connected PV system, which is described from the ideas of construction, software architecture, and development of hardware and so on.

Abstract: Aiming at collapse, disconnection, and ice flash-over problems caused by power grid transmission line icing, this paper proposes a predicting method of transmission line icing. According to historical data and theories of decision tree, calculating out each factors information entropy, with an overall consideration of each influencing factors attribute and attribute value and connections between adjacent layers, we pick out the best testing factor as the root note to complete the model. This model has a clear train of thought, at the same time it has high predicting accuracy and efficiency, which provides a strong guarantee for safely running of power grid transmission line.

Abstract: Transmission line flashing will cause large area and long time of blackouts,it happens in the working voltage,and it poses serious threat to the electric power system. With the development of industry,the increase of power grid capacity and rated voltage level,there are more and more flashing accidents occurred in the power system of power transmission and transformation equipment external insulation,also the damage that they bring about to our economy is getting larger.Aiming at a series of problems caused by transmission line flashing,this paper comes up with an assessment method of transmission line flashing,it improves the forecast accuracy and efficiency so as to ensure the safety operation of transmission.

Abstract: Relay technology is an important technical means to achieve a smooth transition from Long Term Evolution (LTE) to LTE-Advanced (LTE-A). Theoretically, the addition of nodes will improve the performance of the system effectively. While the relay is active nodes, addition of nodes become a new source of interference. Based on the LTE-A simulation platform, the effect of relay node on the system is analyzed.