Advanced Materials Research Vols. 121-122

Abstract: With the development of social, economic, groundwater pollution is becoming a concern in our country. In view of the defiency of traditional finite difference method, in this paper, a proposed hybrid finite analytic method was adopted to solve the problem about groundwater pollution. Testing with some examples and contrasting with finite difference method, we can get the conclusion that the hybrid finite analytic method is available.

Abstract: Temperature dependent oriented growth of ZnO thin film deposited on NaCl (001) substrates using ion beam sputtering was studied by transmission electron microscopy (TEM). Thin films showing a texture due to parallel epitaxy with NaCl (001) as deposited at 100 oC, whereas thin films deposited at 400 oC can form a texture. The microstructure and the epitaxial relationship with the NaCl (001) plane were studied by a high-resolution TEM. The possible causes for the orientation changed with temperature are discussed. The optical transparency of the nanofilms grown from room temperature to 400 oC was measured.

Abstract: Recently, sensor networks are usually applied on collecting remote sensing information. The deployed sensor nodes are separated and responsible for specific purposes, and act as an individual device. They cooperatively transmit sensed data to the base station, as shown in Fig.1. However, the transmitted data are exposed to open environments, and possibly contain confidential information. If malicious attacks interfere in the communication using huge packets to break the communication, thus the system can not work properly. In general, attackers exploit a broadcast storm or a Distributed Denial-of-Service (DDoS) attack to paralyze the entire network. Therefore, this study proposes a queuing theory based scheme to detect whether the system encounters malicious attacks. Our proposed scheme provides the arrival requests with a queuing service on the base station, which is responsible for dealing with transmitted jobs. Once the jammed traffic is anomalous for long periods, the system immediately detects the malicious attacks using our proposed approach.

Abstract: This paper proposed a framework of knowledge cognition and ontology based e-learning system, it presented a learning characteristics based ontology metadata model(LCOM). On the basis of LCOM, according to cognitive theory and to as an example data structure course, a domain knowledge ontology base model was set up．it makes the development of network courses and management of learning resources independent.

Abstract: As the important elements in adaptive optical system used for food safety detection instrument, Micro-deformable mirrors are typical Microelectromechanical systems (MEMS). This paper focuses on the structural optimization of the MEMS Micro-deformable mirror. With the method of finite method analysis, the dynamic characteristics of the micro-mirror are studied by the analysis of modal and frequency respond. The random vibration analysis followed shows the optimized structure parameters of the micro-mirror are effective to improve the dynamic performance of the mirror.

Abstract: This paper presents a non-linear math model on ship power station and numerical simulation, aiming at describing dynamic characteristic of electric propulsion ship shipboard power system precisely. Non-linear differential algebraic equations are given by differential equation modeling theory, concerning with diesel engine speed characteristics, electromagnetic and electrical transient characteristics (Φd, Φq, Ed", Eq", E'q, ω, δ as status variables) of synchronous generator and voltage characteristics of excitation system. Then the non-linear equations are solved by implicit trapezoidal integration method, finally dynamic curves of status variables such as voltage, speed of rotor, three phase current of stator and so on are drawn based on simulation program written by C#.NET. Simulation results demonstrate that the non-linear math model proposed by this paper is reasonable, and the results are theory foundation of transient stability on ship integrated power system for further research.

Abstract: Aiming at the problem of complexity and uncertainty factors existing in network security risk assessment process, an analysis method based on Fuzzy Analytic Hierarchy Process is proposed in this paper. By the theory of fuzzy mathematic, this method establishes the network risk assessment model and constructs fuzzy judgment matrix to determine index weight of each level factor. The example of calculation results shows that the method is feasible and effective.

Abstract: As the transistor sizes continue to shrink, quantum effects will significantly affect the circuit behavior. The inherent unreliability of nano-electronics will have significantly impact on the way of circuits design, so defects and faults of nano-scale circuit technologies have to be taken into account early in the design of digital systems. Fault-tolerant architectures may become a necessity to ensure that the underlying circuit could function properly. In CAD software, a same logic can be made out with different circuits but different design methodology can reach different soft error tolerance ability, so we must find a way to estimate the error rate of the circuit efficiently to make the design more fault tolerant. In this paper, a new way to fault tolerance design in nano-scale circuit by accurate soft error rate (SER) estimation is proposed. Transform matrix is used for SER computation and a design criteria is then proposed. Simulation results show that the proposed transform matrix model is effective for nano-scale circuits and the criteria delivered is suitable CAD tools development in nano-system design.

Abstract: As the energy crisis and the pollution are serious, the exploitation of solar has received more and more attentions. It is well known that for a given solar radiation intensity and solar cell temperature there exists a maximum power point at which the power generated from the PV panel is at its maximum. In order to improve the efficiency of the system, the main method is to regulate the output of array to develop the maximum power point tracking (MPPT). In this paper the principle and control method of DC/DC conversion in grid-connected photovoltaic system are experimentally discussed. The conductance incremental method is analyzed in detail, and an improved variable step-size control method is implemented for MPPT with pulse width modulation. The experimental results prove the feasibility and correctness of the control method.

Abstract: The leakage dissipations of nano-circuits have become a critical concern. Estimating the leakage power of nano-circuits is very important in low-power design. This paper presents a new estimation technology for the active leakage dissipations of adiabatic logic circuits. Based on the power dissipation models of adiabatic circuits, active leakage dissipations are estimated by testing total leakage dissipations with additional capacitances on load nodes of the adiabatic circuits using HSPICE simulations. Taken as an example, the estimation for dynamic and active leakage power dissipations of CPAL (Complementary Pass-transistor Adiabatic Logic) circuits is demonstrated using the proposed estimation technology. The simulation results show that the proposed estimation technology can accurately estimate the active leakage dissipations of CPAL circuits with an accepted error over a wide range of frequencies.