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To the analysis and further development of straight-racket-hit skill of table tennis, visual simulation is established to help finding its character through comparing with straight racket backhand skill. To overcome such flaws as unable to exert enough force and difficult to determine a strike point, an optimal angle to achieve the skill is got through analyzing force of different angle of wrist and forearm. Through analyzing the visual simulation of mechanical arm, a systematic theory is established to orient the training of straight-racket-hit skill.

The photocurrent and spectral response characteristics of gallium arsenide (GaAs) are obtained by a multi-information measurement system, and the evolution of the photocurrent versus the Cs:O flux ratio is investigated. The experimental results show that the photocurrent increases approximately exponentially after the first exposure to Cs until a maximum sensitivity is reached, the detailed evolution process and the ultimate photocurrent are different for different samples. These differences are analysed, and according to the process of coadsorption of Cs and oxygen on GaAs, an equation is presented to explain the increase of photocurrent.

The filling process of plastic precise gear is simulated by CAE software and the factors that influence injection molding accuracy in single cavity mold are discussed in this paper. With the assistant of visualization technology, the mechanism of filling unbalance which influences efficient injection molding was especially studied. The model of filling unbalance was supposed that was verified experimentally by visualization technique. It is clarified that the mechanism of filling unbalance results from dissymmetrical temperature distribution on the cross-section of runner, which is strongly influenced by the shear heat and the cooling process in the runner. At the same time, a new method was proposed for improving the filling imbalance by applying appropriate injection molding process without any changes in runner shape of multi-cavity mold.

This letter outlines the design and manufacture of a miniaturized bandpass filter realized by low-temperature cofired ceramic (LTCC) technology for bluetooth applications. The bandpass filter with a central frequency of 2450 MHz and a 100 MHz passband is designed as a three-dimensional (3-D) structure based on lumped components. Experimental measurements were compared with modeling. The insertion losses in the passband (100 MHz) were less than 1.2 dB and the attenuation was more than 20 dB in the stop band. The area occupied by the filter is 1.6times0.8times0.6 mm3.

This paper presents a new compact 90deg hybrid coupler using multi-layer technology. In order to reduce an intrinsic circuit area of the hybrid coupler, a compact meandered line configuration and a new multi-layer structure design have been adopted. The configuration and structural dimensions of the multi-layer structure were designed and investigated through detailed 3-D electro-magnetic simulations. The measured insertion loss is less than 0.4 dB, and the phase imbalance is less than 3 degree with the frequency range from 380 MHz to 520 MHz. The overall dimension is as small as 16.5 mm times 12.2 mm times 1.66 mm.

A LTCC band-pass filter with dual transmission zeros for Bluetoothtrade application was presented. With the classic network synthesis method, a lumped LC filter was educed and then transformed to physical prototype with LTCC process. This prototype was refined with DOE method, and was implemented in Zhejiang Zhengyuan Electric Co. Ltd. The measured insertion loss is less than 1.8 dB at 2400 MHz, and two transmission zeros are obtained at 1.7 and 7.1 GHz, respectively. They result in 40-45 dB for lower stop band suppression and 45-50 dB for higher stop band reduction. The experimental data agree very well with the 3-D simulation.

The present status of research on negative electron affinity (NEA) GaN vacuum surface electron source is discussed with considering the latest research conclusions from our country and foreign country. Some valuable results about GaN vacuum electron source have been obtained including the theory of photoemission, the surface depuration method, the activation technique for GaN photocathode, the measurement of spectral response, the characteristics of material etc. The mechanism of photoemission for NEA GaN vacuum electron source is studied preliminarily. The depuration method of obtaining the atom cleanness surface is given. The GaN material is effectively activated with Cs or Cs/O. The spectral response of GaN vacuum electron source material is measured. The material characteristics affecting the quantum efficiency of the electron source are analyzed. The next investigation is also mentioned.

Aiming at determining the quantum efficiency of fully activated negative electron affinity(NEA) GaN photocathodes, we have investigated the spectral response of NEA GaN photocathodes by using a dedicated ultraviolet spectral response measurement instrument. The quantum efficiency curve of reflection-mode NEA GaN photocathode has been obtained in the band region from 230nm to 400nm. The experimental results show that the quantum efficiency of reflection-mode NEA GaN photocathode reaches up to 37.4% at 230 nm, and at 365 nm, which is the threshold of GaN photocathode, the quantum efficiency remains 3.75%. A sharp cutoff characteristic with over two orders of magnitude degradation from 230 nm to 400 nm has been observed. Based on the former research results, the factors influencing quantum efficiency were also comprehensively analyzed in the paper.

The photocurrent curves during either Cs or Cs/O activation of GaN photocathode were tested by using dedicated experimental system for activation and evaluation of negative electron affinity （NEA） photocathode. Aiming at explaining the formation of NEA property of GaN photocathode and according to the rule of photocurrent change during activation period and the surface model of a fully activated photocathode，the activation mechanism for NEA GaN photocathode was studied. The experiment results show that：the obvious NEA property is be induced in GaN photocathode mainly due to the activation by Cs. The increase extent of photocurrent is not large after introducing O during Cs/O activation process for GaN photocathode. The NEA property formation reasons of GaN photocathode after being activated successfully can be well explained using the double dipole layer model ［GaN（Mg）：Cs］：O—Cs.

The photocurrent curves of reflection-mode GaAs photocathodes as a function of time, when were illuminated by white light with an intensity of 0, 33 and 100lx, respectively, were measured using a multi-information measurement system. The calculated lifetimes of cathodes are 320, 160 and 75min, respectively, showing that the stability of cathodes degraded with the increase of light intensity. The lifetime of cathode, illuminated by white light with an intensity of 100lx, while no photocurrent was being drawn during the illumination, was 100min. Through comparison, we found that the influence of illumination on cathodes stability is greater than that of photocurrent. The quantum-yield curves of cathodes as a functions of time, when illuminated by white light with an intensity of 33lx, were measured also. The measured results show that the shape of the yield curves changes with increasing illumination time due to the faster quantum-yield degradation rate of low energy photons. Based on the revised quantum-efficiency equations for the reflection-mode cathodes, the variation of yield curves are analyzed to be due to the intervalley diffusion of photoelectrons and the evolution of the surface potential barrier profile of the photocathodes during degradation process.