A simulation system used in the arc welding short circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical exper...A simulation system used in the arc welding short circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical experiments. The simulation system can be used to simulate and test the current waveform control parameters with welding variables. By this simulation system, the influence regularities of the current waveform control parameters in the CO 2 arc welding droplet short circuit transfer process can be got. Moreover, the basic mode of real time current waveform control can be also established by the simulation testing.展开更多
Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding (GMAW-S) process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been i...Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding (GMAW-S) process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1mm and 3mm mild steel at speed of 1.2m/min. The stable GMAW-S process under high speed welding condition has been achieved by optimizing the parameters.展开更多
A generalized mathematical model of human body current threshold for perception was established and the current flowing through human body could be arbitrary cyclical waveforms.The relationship between human body curr...A generalized mathematical model of human body current threshold for perception was established and the current flowing through human body could be arbitrary cyclical waveforms.The relationship between human body current threshold for perception and current frequency, true root mean square(RMS) value and influence factor was described.A test system was established based on electroencephalogram(EEG) to study the relationship between human body current threshold for perception and current waveform, frequency and duty cycle so that the data could be obtained objectively and reliably.At least 850 groups of current threshold for perception and 16-lead EEGs were acquired.The theoretical analysis are verified by experimental data, and an amendment proposal on leakage current evaluation limits specified in International Electro-Technical Commission(IEC) standards is suggested.展开更多
- Experimental study and theoretical analysis show that the critical value of relative wave height (H/ d)b given by Goda and the critical wave steepness (H/ L)b given by Michell and Miche can be adopted as the spillin...- Experimental study and theoretical analysis show that the critical value of relative wave height (H/ d)b given by Goda and the critical wave steepness (H/ L)b given by Michell and Miche can be adopted as the spilling breaking indices of regular waves. According to the same principle, a systematic theoretical analysis and experiment of irregular waves have been done by the authors in order to solve the breaking problem of irregular waves. It is indicated that the authors’ method for determining wave breaking of regular waves can also be used for irregular waves.展开更多
Structure of main air discharging switch and a crowbar TVS (triggered vacuumswitch) are designed and their triggering characteristics are investigated. The experimental resultsshowed that for TVS the operating voltage...Structure of main air discharging switch and a crowbar TVS (triggered vacuumswitch) are designed and their triggering characteristics are investigated. The experimental resultsshowed that for TVS the operating voltage range is from 1.3 kV to 120 kV, its maximum delaytime is 400 ns and its jitter is±10 ns. Based on these results the crowbar 10/350 μs (i.e., witha front time of 10 μs and a duration of 350 μs) pulse current circuit and its controlling circuitare designed. With a 10 μF stored capacitor C and a 6 μF waveform forming induction, a pulsecurrent is generated with a maximum of 100 kA, front time of 10 ns and duration of 350 μs. Thispulse waveform can be used for testing SPD (surge protective devices).展开更多
文摘A simulation system used in the arc welding short circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical experiments. The simulation system can be used to simulate and test the current waveform control parameters with welding variables. By this simulation system, the influence regularities of the current waveform control parameters in the CO 2 arc welding droplet short circuit transfer process can be got. Moreover, the basic mode of real time current waveform control can be also established by the simulation testing.
文摘Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding (GMAW-S) process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1mm and 3mm mild steel at speed of 1.2m/min. The stable GMAW-S process under high speed welding condition has been achieved by optimizing the parameters.
基金Acknowledgement The authors are grateful to the financial support for this research from the National Natural Science Foundation of China (Key Program Grant No. 50936003).
基金Supported by the Ministry of Science and Technology of China (No. NCSTE-2006-JKZX-167)Beijing Key Laboratory (Measurement and Control of Electro-mechanical Systems) (No. 82063005)
文摘A generalized mathematical model of human body current threshold for perception was established and the current flowing through human body could be arbitrary cyclical waveforms.The relationship between human body current threshold for perception and current frequency, true root mean square(RMS) value and influence factor was described.A test system was established based on electroencephalogram(EEG) to study the relationship between human body current threshold for perception and current waveform, frequency and duty cycle so that the data could be obtained objectively and reliably.At least 850 groups of current threshold for perception and 16-lead EEGs were acquired.The theoretical analysis are verified by experimental data, and an amendment proposal on leakage current evaluation limits specified in International Electro-Technical Commission(IEC) standards is suggested.
文摘- Experimental study and theoretical analysis show that the critical value of relative wave height (H/ d)b given by Goda and the critical wave steepness (H/ L)b given by Michell and Miche can be adopted as the spilling breaking indices of regular waves. According to the same principle, a systematic theoretical analysis and experiment of irregular waves have been done by the authors in order to solve the breaking problem of irregular waves. It is indicated that the authors’ method for determining wave breaking of regular waves can also be used for irregular waves.
基金supported by the New Century Talent Foundation of Ministry of Education of China (NCET-08-0438)
文摘Structure of main air discharging switch and a crowbar TVS (triggered vacuumswitch) are designed and their triggering characteristics are investigated. The experimental resultsshowed that for TVS the operating voltage range is from 1.3 kV to 120 kV, its maximum delaytime is 400 ns and its jitter is±10 ns. Based on these results the crowbar 10/350 μs (i.e., witha front time of 10 μs and a duration of 350 μs) pulse current circuit and its controlling circuitare designed. With a 10 μF stored capacitor C and a 6 μF waveform forming induction, a pulsecurrent is generated with a maximum of 100 kA, front time of 10 ns and duration of 350 μs. Thispulse waveform can be used for testing SPD (surge protective devices).