研究了以银氨溶液和抗坏血酸溶液为原料,在截断流管式反应器中制备亚微米球形银粉.试验验证了在截断流管式反应器中还原制备亚微米球形银粉的可控性,考察了反应物浓度 、搅拌速度 、反应时间 、温度等条件对银粉颗粒及形貌的影响.结果表明:在适宜条件下,用银氨溶液和抗坏血酸溶液可制备亚微米级银粉,所得银粉分散性好,主要约0.3μm.该方法简单易操作,银粉颗粒均匀可控.

In testing the electrical safety performance of leakage current on electrical products,human current threshold for perception is one of the most important parameters.Traditionally,the testing of human current threshold for perception depends on their subjective feelings,and has poor reliability and consistency.In the paper,an experiment research method is established based on the principle of EEG(electroencephalogram) activity,382 groups of experimental data are obtained,and the relationship between current threshold for perception and EEG is explored.The study finds that there is obvious relation between current threshold for perception and fre-quency-domain EEG transformed characteristic from time-domain EEG by FFT(Fast Fourier Transform).The vast majority of people EEGs have obvious change when perception threshold currents flow through human bod-ies,which includes the amplitude decreasing or increasing of α or β waves.But further study about its clear changing rule is needed,which is helpful for confirming the electrical safety performance objectively.

The electrical safety testing system for household and similar electrical appliances,which could test and analyze the parameters as leaking-current,with standing-voltage and earth-resistance has been researched.The system is composed of DSP,the test loop and the computer.The system realizes the 0-1MHz frequency band AD sampling by integrated high speed AD converter of DSP.The reappearance of the actual waveforms offers the users comprehensive and intuitive understandings of the testing index.The experiment result indicates the system possesses many characteristics,such as according with the latest test standards,high accuracy and automatic comprehensive test.

The working principle, design and implementation are described for a new design of leakage current test system, which is composed of human body's impedance network, detector switch circuit, the circuit including MCU and CPLD for control and measurement, can achieve peak detection, true RMS detection, real-time display of waveform. According to many international testing standards such as IEC, UL, GB, the system has a broader measuring scope of frequency and higher accuracy with good human-computer interface and calibration function.