Advanced Materials Research Vols. 706-708

Abstract: To guarantee the security of composite insulators as tension strings applied to ultra-high voltage engineering, it is necessary to study the mechanical properties of composite insulator regarding break impact. The test system was designed and the implementation plan was developed. Test was done to two insulator strings broken and the dynamic impact factor under different broken conditions at different tension was obtained accordingly, which provides reference and evidence for further study on mechanical properties of composite insulator and development of applicable design specifications.

Abstract: In the study of three-dimensional shape prediction of SMT solder joints, the software Surface Evolver has been widely applied as a quick and accurate effective tool for the prediction of solder joints shape. But the model it builds is not able to be directly imported into any finite element analysis software like ANSYS, and even after the import it still needs a lot of time to mend the import model. For this issue, to predict of the solder joints shape of ball grid array (BGA), the implement programs of three conversion methods of point-line-area method, axisymmetric method and infinitesimal method are given. By comparison, axisymmetric method and infinitesimal method are more suitable for the shape conversion of BGA solder joints.

Abstract: In this paper, PLCC lead free solder joint’s thermal fatigue lifetime is analyzed by using the Response Surface Methodology, combined with solder joint’s shape prediction and finite element simulation. Three key solder joint’s process parameters, pad length, gap height and solder paste’s volume are chosen to build an orthogonal array , 25 PLCC lead free SAC305 solder joint’s models with different parameters combination are built in Surface Evolver to predict the solder joint’s shape. Then the PLCC device’s surface shape models in Surface Evolver are converted to three-dimensional finite element models by using a special method. Thermal analyses give the distribution and the change of thermal stress and strain, which show the dangerous solder joint in the whole PLCC device and position with weak thermal reliability in single solder joint. Furthermore, the PLCC solder joints’ thermal fatigue lifetime are calculated with the modified Coffin-Manson equation, and the series of thermal fatigue lifetime data are processed by the Response Surface Methodology. Regression equation between thermal fatigue lifetime and the three key factors is concluded. With the solder joint’s influencing rule on thermal fatigue lifetime and the solder joint’s process parameter combination belong to the highest thermal fatigue lifetime, assembly process of PLCC is improved and then enhance the PLCC solder joint’s reliability.

Abstract: Research on the temperature field and stress field of tuyere by numerical modeling and analyse the influence of structure on tuyere's property.

Abstract: In this paper, a novel method to recognize rotor fault pattern was proposed based on rank-order morphological filter, harmonic window decomposition, sample entropy and grey incidence. At first, the line structure element was selected for rank-order morphological filter to denoise the original signal. Then, the six feature frequency bands which contain the typical fault information were extracted by harmonic window decomposition that needs not decomposition; and sample entropy of each band was calculated. Finally, these sample entropies could serve as the feature vectors, the grey incidence of different rotor vibration signals was calculated to identify the fault pattern and condition. Practical results show that this method can be used in fault diagnosis of rotating machinery effectively.

Abstract: In this work, we apply the Hauser technique and combine a newer inversion layer charge model to extract the effective channel carrier mobility (μ_eff) and threshold voltage (V_th) of several high-voltage DDD MOSFETs with different dimensions in channel length and width. This paper proposes and demonstrates that our new method is a novel and efficient to extract the carrier mobility and threshold voltage in the DDD MOSFET, meanwhile, the extracted data is well consistent with UT model. And, only the extracted values by our new method and BCV method can clearly reflect the narrow-width effect which results from the so called LOCOS isolation technique. Therefore, it is clearly to see that our extraction technique can exactly reflect the device characteristics in high-voltage DDD MOSFETs.

Abstract: P2P simulator has many basic characteristics such as pattern, P2P architecture supported, mode triggered, develop language and so on. As well as P2P simulators are assessed according to a number of criteria grouped under the headings simulator architecture, usability, scalability, Statistics, Underlying Network Simulation etc. As representative, five P2P simulators are compared in terms of the basic characteristic and the important criteria. A table is given about contrast of P2P simulators on basic characteristic and parameter of criteria. Consequently, supply right smart advantage for P2P researcher to select P2P simulator.

Abstract: The detected structures in a CUP wafer by sensing (leakage) analysis are presented in this paper. The pad structures are designed by the ADS2009 & TSMC 0.18um CMOS processes design rules, and use some electrostatic discharge (ESD) protection devices and circuits under these pads. Furthermore, the signal will be passed through these ESD devices or circuits on the top-metal pad as a sinusoidal, square, or ESD pulse waveform being injected. It is found that during an ESD occurred situation, a strong signal coupling can be sensed by the ESD protection circuits.

Abstract: This paper puts forward a new improved entropy method, which fixes the problem of traditional entropy weight method that entropy weights present the wrong message of entropy when all the entropy values are close to 1. The proposed method achieved efficient performance by designing calculation model of BP network. Firstly, the synthesis weights of power quality indexes were calculated by rank correlation analysis and the improved entropy method, which avoids the one-sidedness of subjective or objective. And the quantitative values of multi-index were obtained. Then a calculation model of BP network to realize this evaluation method is designed in this paper, making it more efficient and more practical. Finally, the evaluation of a power supply bureau has verified the effectiveness of the proposed method.

Abstract: The dynamical process of underwater explosion bubble is a very complicated phenomenon with many facets needed to consider. After detonation, shock wave propagates in a very short time while the oscillation of bubble occurs in a long time. Bubble pulsation can cause serious damage for the structures nearby due to the whipping effect, bubble pulse or water jet impact in the collapse phase. This paper presents an application of Finite Element Method (FEM), namely Eulerian technique, to simulate the dynamical process of bubble and numerical results were verified by an experiment. This approach shows it's feasibility in simulating the bubble pulsation as well as the formation of water jet at the end of first contracting circle. Although numerical model was simplified by the boundary conditions, the success of this method is foundation for further study of bubble such as in predicting the damages of both nearby submerged structures as well as floating structures.