徐州市英语培训市场调查分析

本文运用市场调查方法,对徐州市英语培训市场宏观环境因素及市场需求现状进行调查;分析徐州市英语培训需求市场的现状、特征,并对市场需求趋势做出预测。     

利用MATLAB对彩色图像进行低通滤波

彩色图像的数据量比较大，在进行压缩与传输时会增加工作负担。通过对图像的频谱特性分析可以知道，一幅图像中的低频成分要远远高于高频成分。大部分图像信息集中在低频部分。因此，在不过于苛刻地计较图像的再现质量的场合下，如果将代表图像边缘，跳越部分．以及颗粒噪声的高频部分通过低通滤玻器滤除的话就会减少图像数据量，进而减少下一步的工作量。本文主要以真彩色RGB图像为例，介绍一种对其进行低通滤波的方法。     

汽车发动机动力特性的计算机模拟

结合汽车动力性分析过程,阐述了如何建立发动机动力特性的计算方程,并根据实例的计算结果,分析比较了各种方法的优缺点和对汽车动力性评价指标的影响,从而找出一种较为精确的计算方法。     

当代多芯片组装技术

与传统的封装技术相比，多芯片组装技术具有更高的封装密度和更优异的性能。多芯片组装技术正在蓬勃发展，归当代的代表性技术。     

Organic thin film transistors: Materials,processes and devices

For the past ten years, organic materials have been extensively investigated as an electronic material for thin film transistor (TFT) devices. Organic materials offer strong promise in terms of properties, processing and cost effectiveness and they can be used in flat panel displays, imagers, smart cards, inventory tags and large area electronic applications. In this review, we summarize the current status of the organic thin film transistors including substrate materials, electrodes, semiconducting and dielectric layers; organic thin film preparation methods; morphological studies for organic thin films; electrical characterization of gate dielectric layers and semiconducting active layers; and characterization of the OTFTs. Future prospects and investigations required to improve the OTFT performance are also given. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Effects of various baffle designs on acoustic characteristics in combustion chamber of liquid rocket engine

Effects of various baffle designs on acoustic characteristics in combustion chamber are numerically investigated by adopting linear acoustic analysis. A hub-blade configuration with five blades is selected as a candidate baffle and five variants of baffles with various specifications are designed depending on baffle height and hub position. As damping parameters, natural-frequency shift and damping factor are considered and the damping capacity of various baffle designs is evaluated. Increase in baffle height results in more damping capacity and the hub position affects appreciably the damping of the first radial resonant mode. Depending on baffle height, two close resonant modes could be overlapped and thereby the damping factor for one resonant mode is increased exceedingly. The present procedure based on acoustic analysis is expected to be a useful tool to predict acoustic field in combustion chamber and to design the passive control devices such as baffle and acoustic resonator.     

An experimental study on the axial collapse characteristics of hat and double hat shaped section members at various velocities

In this study, the axial collapse tests were performed under either static (or quasi-static) or impact loads with several collapse velocities based on the expectation that para-closed sections of the front-end side members (spot welded hat and double hat shaped section members) would show quite different collapse characteristics from those for seamless section. The test results showed that both of the hat and double hat shaped section members failed in the stable sequential collapse mode in the static or quasi-static collapse tests, while the double hat shaped section members underwent the unstable collapse mode especially when the impact velocity is high. The mean collapse loads in the hat shaped section members increase with collapse velocity for all the cases of the static, quasi-static, and impact collapse tests. In the double hat shaped section members, however, the mean collapse loads decrease with increase in collapse velocity in the impact tests.     

The effects of impeller characteristics in the hydrogenation of aniline on Ru/C catalyst

Effects of impeller characteristics have been studied in the hydrogenation of aniline on Ru/C catalyst. Dual impellers were employed and the experiments were performed at 300 rpm using a lab-scale reactor. Reaction with disk turbines (DT) resulted in the higher cyclohexylamine (CHA) selectivity and higher reaction rate compared to that with pitched blade turbines (PBT). When a combination of PBT and DT impellers was employed, high product selectivity and reaction rate were obtained and the selectivity was maintained constant. Changes in the product selectivity with the impeller geometry were explained in terms of the relative rates of the side reactions depending on the hydrogen concentration in the reaction mixture.     

基于车辆行驶状态的EPS助力特性研究

助力特性是电动助力转向系统控制的依据。本文从保证行车安全的观点出发,分析了车辆行驶状态参数与EPS助力矩的关系,提出了基于车辆行驶状态的EPS助力特性,并用Matlab/Simulink进行了仿真,仿真结果表明该助力特性是合理的。     

微电机制造工艺现状及发展动向

微电机行业是技术密集型、资金密集型和劳动密集型行业。微电机制造工序多,工艺装备数量大,加工精度要求高,一些微特电机还有特殊的使用环境要求。分析了当前我国微电机行业制造工艺技术的特点和状况,阐述了今后微电机制造工艺技术的发展趋势和方向。