Advanced Materials Research Vols. 383-390

Abstract: A relative navigation and control scheme based on multiple camera systems was presented for autonomous operations in close proximity for autonomous air refueling (AAR) mission. The relative navigation system employed non-iterative fast global optimal pose estimation algorithm, and the result was filtered and fused with velocity’s measurements to increase accuracy and robustness by using Kalman filtering algorithm. To attenuate effect of tanker’s vortex and atmospheric turbulence, an H-infinity tracking control law was designed for docking phase of air refueling. Simulation results showed that accuracy of both vision navigation system and trajectory tracking could meet requirements of aerial refueling.

Abstract: The symplectic algorithm is a kind of new numerical integration methods. This paper proposes the application of the explicit and symplectic Runge-Kutta-Nyström method to solve the differential equations encountered in the power system transient stability simulation. The proposed method achieves significant improvement both in speed and in calculation precision as compared to the conventional Runge-Kutta method which is widely used for power system transient stability simulation. The proposed method is applied to the IEEE 145-bus system and the results are reported.

Abstract: Redundancy technique is an effective method to improve the ability of mission reliability, safety reliability and fault tolerant. With redundancy technique, it will increase additional system software and hardware resources, such as fault monitor module and channel switch module etc. In allusion to sensor fault, serial fault, controller fault and motor fault, this paper designs and researches the strategy of fault logic, fault management and fault reconstruction, appropriately distributes the system resources, thus effectively processes fault monitoring and isolating, and sufficiently improves mission reliability, safety reliability and fault tolerant ability of the dual-redundancy brushless direct current electric rudder loop.

Abstract: On the basis of introducing the causes and hazards of islanding, the paper classifies and generalizes the testing methods used currently about islanding. It is shown that applying single method to detect islanding will bring some wrong judgments. It is difficult to determine the protection thresholds by a single detection method, which will decrease protection sensitivity and result in system losses. This paper studies a method based on fuzzy clustering, which integrates variations of voltage amplitude and frequency change, mutations of current phase and voltage phase, as well as formation of voltage harmonics and so on, and determines the formation of islanding and the appropriate protection criterion.

Abstract: This paper first gives out the harmonic coupled equivalent model for the Thyristor Controlled Reactors (TCRs) and the converter. Then, the harmonic generating characteristics of the TCRs and the converter are investigated based on the proposed model. With the help of the equivalent model, the impact of each harmonic contribution component is quantified. Moreover, based on the characteristics analysis of the model, two simplified model are proposed which are useful for simplifying the harmonic analysis of systems with TCRs and converters.

Abstract: To overcome the nonlinear and slow-varying factor in hydraulic system and the uneasy-building model of erection system, the single neuron self-adaptive PID controller is designed. To solve the conflict between the speed and the stability in erecting, The erecting system based on virtual instrument is designed. The system uses a data acquisition card simultaneously to acquire the test data and the feedback signal and control the hydraulic system, utilizes the module method and the technique of mixed-program between LabWindows/CVI and Matlab based on ActiveX technique to design application software. The results of experiment shows that the system with high precision of testing and controlling is operated conveniently and universally and can satisfy the requirement of the erection system.

Abstract: MCNP input file has the characteristics of complicated form and is error-prone in describing geometry model. An algorithm of converting UG model to MCNP geometry model was researched and implemented through UG OPEN API and C++ programming language. The algorithm improves the efficiency of describing MCNP geometry model, and provides a valuable reference to MCNP users.

Abstract: Electro Hydraulic Brake (EHB) system plays an important role for improving vehicle active safety. In this paper, the dynamic behavior of EHB system is discussed. From its working principle, a dynamic model of quarter EHB system is established based on AMESim and Matlab. To analyze performance of the proposed EHB system, the strategy of Single-Neuron PID regulation is presented and a typical numerical case is given. The results show that this strategy can obtain good performance and proper parameters can improve the dynamic characteristics of EHB system effectively.

Abstract: There are many kind of clamps used in geological exploration, and the hobbyhorse clamp obtains the widespread application because of its simple structure and reliable clasp. But theoretical analysis shows problem of the hobbyhorse clamp that clamping force is too small to overcome the resultant force of dead weight of drill pipe and tangential force from unscrewing torsional moment when drill rods in underground hole are tailed off gradually. This paper bring forward a new project on the basis of hobbyhorse clamp holder, established its static mechanics model based on the structural and mechanical analysis. Practice application has proved that the design is successful.

Abstract: Power grid suffers tremendous economic loss in extreme ice disaster weather, suggesting that it lacks immediate precautionary system. On the basis of the standards of Q/GDW179-2008 and IEC60826-2003, the curve of transmission line design loads is built up. In view of ransom character for load-strength of transmission line, according to load-strength interference theory, a short-term wind and ice loading risk model is established, which is a time-dependent wind and ice loading model, and can be calculated unreliability probability and fault rate, showing risks about cluster fault and common fault. Furthermore, wind and ice loads are divided into five states, which show risk margin of loads. It also can provide precautionary information for operator, and can present risk measurement on time scale.