Harmonic Analysis and Suppression of High-frequency Welding Devices

This paper analyzes the structure and line current waveform of 3-phase AC voltage regulation circuit. As an application of 3-phase AC voltage regulation circuit, a high-frequency welding device's simulation model and harmonic analysis of line current are presented. Results of simulation are compared to field measurements. The two are in a good agreement, so this simulation model is correct. Two single-tuning filters and one second-order HPF are designed according to the device's harmonic condition. Simulation results of the circuit with filters indicate decrease of the harmonics in current of power supply, and the waveform is close to sinusoidal wave, which prove correctness of the solution to harmonics pollution.     

Portable ECG Monitor Front- ended Design with C8051 F020

The electrocardiogram (ECG) signal is a recording of the electrical activity on the body surface generated by the heart frequency of which is weak and low. Many researchers devote themselves to get more perfect ECG in many ways. This article introduces the characterize of an ECG signal , then discusses the requirements for the sampling circuit of an ECG. Since there are some shortcoming in common design means, the authors give an effective circuit. The system is composed of a low-cost , low-power and high-performance MCU C8051F020 , amplifier AD620 , right-leg drive circuit ,communication circuit and power management circuit. Then software design is given which is used to sampling and filtering ECG signal. Levkov filter arithmetic and smooth filter arithmetics are used in this design. In the end , the authors advance a distributing and networking ECG monitor system.     

A Method of Adaptive Fuzzy Classfication on Rockmass Blast Ability

This paper presents a series of targets which are usefull for engineering.The paper also presents an adaptive weight function according to the fail mechanism of rockmass and a fuzzy aynthetic evaluation medel on rockmass blast ability.The model is applied to evaluate the blast ability of rockmass in an engineering and the result shows that the model is effective.     

Developing a Recognition System of Gun-code

Intelligent recognition system of gun code is designed , which achieves online recognition of gun code. We applied video camera to get image, and some special technique in this deformed character recognition. As well, we applied dynamic template matching to get a better result.     

发动机用平板型空滤器流动阻力特性分析和改进

为减小平板型空滤器流动阻力以增大进气量,对平板型空滤器流动阻力特性开展了实验研究,获得了空滤器流动阻力随流量变化的规律和阻力构成成分。阻力随流量的增大而加速增大,滤芯阻力约占整个空滤器阻力的一半,入口流量为120 m 3/h时,总阻力为915.3 Pa,滤芯阻力为426.4 Pa。在实验获得滤芯阻力参数的基础上,提出采用多孔介质跃升模型对平板型空滤器内部流场开展三维数值仿真分析,结果表明,仿真结果与实验结果比较吻合,最大误差为5.67%。滤芯阻力同样约占整个阻力的一半,另一半阻力主要为出口处阻力,其余壁面阻力约占15%。最后,在实验和仿真分析的基础上,提出了改进模型并进行了仿真分析。结果表明,改进模型阻力有较大程度的下降,入口流量为120 m 3/h时,总阻力为588.2 Pa,较原始模型下降了32.2%;增大空滤器流通横截面积是减小阻力以增大进气量的有效手段,改进空滤器壁面的平滑性是补充措施。     

改进田间杂草识别图像预处理方法的研究

机器视觉系统采集到的田间杂草图像在分割之前,需要对图像进行预处理来改善图像的视觉效果。为了提高图像的预处理效果,针对杂草图像的特点,在多级加权中值滤波算法的基础上,增加3个不同大小尺寸的二维滤波掩膜,使得在去除噪声的同时尽可能保留了更多的细节特征,从而改善了田间杂草图像的滤波效果。     

厌氧水解-移动床生物膜反应器处理香精调料废水的研究

我国的香精调料行业发展很快,废水的成分复杂,浓度高,必须采用多种技术联合处理。针对某食用香精调料企业的废水特点,采用化学混凝预处理、厌氧水解和好氧移动床(MBBR)组合工艺处理,生产性装置的运行效果表明,COD,BOD5,SS和NH3-N等去除效率突出,完全可以达到排放标准,TN和TP的去除效率可分别达到66.3%~69.7%和83.0%~90.2%,其中,TN是由厌氧段反硝化和MBBR同步硝化反硝化实现,TP则通过化学混凝而去除。厌氧水解和MBBR是去除有机物和生物硝化的核心,曝气生物活性炭滤池进一步保证了出水的水质。