A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simul...A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simultaneously. To enhance the immunity, the values of capacitance and inductance should be increased, which are actually limited by coal mine explosion-proof standards. Hence, for the first time, an active filter was applied in an electromagnetic interference （EMI） output filter. As a result, the interference within 30 MHz clearly weakened, but the frequency spectrum had a wide range. An EMI input filter and ferrite beads were adopted to restrain higher frequency interference. An output interference spectrogram of the substation was obtained with an analyzer. The results indicate that the improved complex filtering markedly help to control interference. With the support of improved complex filtering and other enhancing immunity means about I/O ports, the substation managed to pass both the EFT/B immunity test and the explosion-proof test synchronously. We conclude that improved complex filtering is of vital importance in enhancing the electromagnetic compatibilitv （EMC） of the coal mine monitoring system.展开更多
Underground Electro Magnetic Interference (EMI) has become so serious that there were false alarms in monitoring system,which induced troubles of coal mine safety in production.In order to overcome difficulties caused...Underground Electro Magnetic Interference (EMI) has become so serious that there were false alarms in monitoring system,which induced troubles of coal mine safety in production.In order to overcome difficulties caused by the explosion-proof enclosure of the equipments and the limitation of multiple startup and stop in transient process during EMI measurement,a novel technique was proposed to measure underground EMI distri- bution indirectly and enhance Electromagnetic Campatibility(EMC) of the monitoring sys- tem.The wavelet time-frequency analysis was introduced to underground monitoring sys- tem.Therefore,the sources,the startup time,duration and waveform of EMI could be as- certained correctly based on running records of underground electric equipments.The electrical fast transient/burst (EFT/B) was studied to verify the validity of wavelet analysis. EMI filter was improved in accordance of the EMI distribution gotten from wavelet analysis. Power port immunity was developed obviously.In addition,the method of setting wavelet thresholds was amended based upon conventional thresholds in the wavelet filter design. Therefore the EFT/B of data port was restrained markedly with the wavelet filtering.Coor- dinative effect of EMI power and wavelet filter makes false alarms of monitoring system reduce evidently.It is concluded that wavelet analysis and the improved EMI filter have enhanced the EMC of monitoring system obviously.展开更多
1990年,加拿大多伦多证券交易所推出了第一支ETF"多伦多指数参与单位"(Toronto Index Participation Units,TIPS),标志着ETF的诞生.1993年,美国推出了第一支ETF基金SPDR,从此ETF便得到了迅速发展.1995年至2000年间,ETFs的资...1990年,加拿大多伦多证券交易所推出了第一支ETF"多伦多指数参与单位"(Toronto Index Participation Units,TIPS),标志着ETF的诞生.1993年,美国推出了第一支ETF基金SPDR,从此ETF便得到了迅速发展.1995年至2000年间,ETFs的资产每年都以翻倍的速度增长,备受大多数低成本指数基金倡导者的青睐.这与交易所交易基金所具有的优点是分不开的--低费用率、日内交易、基金日内净资产价值没有实质性溢价或折价、具有较高税收效率等,而这些优点又与所在证券市场的法律、监管、税收、市场环境等因素密切相关.这里我想通过对共同基金和ETF的比较,谈谈在美国ETF为什么会具有较高的税收效率.展开更多
Background : Hypertension and dyslipidemia are considered reversible risk factors for cardiovascular disease. The purpose of this study was to explore the impact of traditional and nontraditional blood lipid profiles ...Background : Hypertension and dyslipidemia are considered reversible risk factors for cardiovascular disease. The purpose of this study was to explore the impact of traditional and nontraditional blood lipid profiles on the risk of left ventricular hypertrophy(LVH) and to explore the superposition effect of dyslipidemia combined with hypertension.Methods : Data on 9134 participants(53.5 ±10.3 years old) from the Northeast China Rural Cardiovascular Health Study(NCRCHS) were statistically analyzed. The blood lipid profile was measured by total cholesterol(TC), low-density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C), total glyceride(TG), and calculated nontraditional blood lipid indices including non-HDL-C, atherosclerosis index(AI), TC/HDL-C, and residual cholesterol(RC).Results : After the adjustment of age and gender, the odds ratios(ORs) of LVH in patients with hypertension, high LDL-C, high non-HDL-C, high AI, and high TC/HDL-C were 3.97(3.31– 4.76), 1.27(1.02– 1.59), 1.21(1.04– 1.39), 1.33(1.15– 1.53), and 1.42(1.22– 1.65), respectively. After full adjustment of potential confounding factors, high AI and TC/HDL-C were associated with LVH rather than traditional blood lipid indices.The combination of hypertension and nontraditional dyslipidemia(defined by high AI and TC/HDL-C) was associated with the highest risk of LVH, especially in participants under 45 years of age. The risk was more significant in men, 5.09-fold and 6.24-fold,respectively, compared with 3.66-fold and 4.01-fold in women.Conclusions : People with dyslipidemia defined by nontraditional blood lipid indices(high AI and high TC/HDL-C) and hypertension were more likely to develop LVH.展开更多
基金Project 50674093 supported by the National Natural Science Foundation of China
文摘A monitoring system is an important guarantee of safety in a production mine. However, not all monitoring substations pass the electrical fast transient/burst （EFT/B） immunity test and the explosion-proof test simultaneously. To enhance the immunity, the values of capacitance and inductance should be increased, which are actually limited by coal mine explosion-proof standards. Hence, for the first time, an active filter was applied in an electromagnetic interference （EMI） output filter. As a result, the interference within 30 MHz clearly weakened, but the frequency spectrum had a wide range. An EMI input filter and ferrite beads were adopted to restrain higher frequency interference. An output interference spectrogram of the substation was obtained with an analyzer. The results indicate that the improved complex filtering markedly help to control interference. With the support of improved complex filtering and other enhancing immunity means about I/O ports, the substation managed to pass both the EFT/B immunity test and the explosion-proof test synchronously. We conclude that improved complex filtering is of vital importance in enhancing the electromagnetic compatibilitv （EMC） of the coal mine monitoring system.
基金the National Natural Science Foundation of China(50674093)
文摘Underground Electro Magnetic Interference (EMI) has become so serious that there were false alarms in monitoring system,which induced troubles of coal mine safety in production.In order to overcome difficulties caused by the explosion-proof enclosure of the equipments and the limitation of multiple startup and stop in transient process during EMI measurement,a novel technique was proposed to measure underground EMI distri- bution indirectly and enhance Electromagnetic Campatibility(EMC) of the monitoring sys- tem.The wavelet time-frequency analysis was introduced to underground monitoring sys- tem.Therefore,the sources,the startup time,duration and waveform of EMI could be as- certained correctly based on running records of underground electric equipments.The electrical fast transient/burst (EFT/B) was studied to verify the validity of wavelet analysis. EMI filter was improved in accordance of the EMI distribution gotten from wavelet analysis. Power port immunity was developed obviously.In addition,the method of setting wavelet thresholds was amended based upon conventional thresholds in the wavelet filter design. Therefore the EFT/B of data port was restrained markedly with the wavelet filtering.Coor- dinative effect of EMI power and wavelet filter makes false alarms of monitoring system reduce evidently.It is concluded that wavelet analysis and the improved EMI filter have enhanced the EMC of monitoring system obviously.
文摘1990年,加拿大多伦多证券交易所推出了第一支ETF"多伦多指数参与单位"(Toronto Index Participation Units,TIPS),标志着ETF的诞生.1993年,美国推出了第一支ETF基金SPDR,从此ETF便得到了迅速发展.1995年至2000年间,ETFs的资产每年都以翻倍的速度增长,备受大多数低成本指数基金倡导者的青睐.这与交易所交易基金所具有的优点是分不开的--低费用率、日内交易、基金日内净资产价值没有实质性溢价或折价、具有较高税收效率等,而这些优点又与所在证券市场的法律、监管、税收、市场环境等因素密切相关.这里我想通过对共同基金和ETF的比较,谈谈在美国ETF为什么会具有较高的税收效率.
文摘Background : Hypertension and dyslipidemia are considered reversible risk factors for cardiovascular disease. The purpose of this study was to explore the impact of traditional and nontraditional blood lipid profiles on the risk of left ventricular hypertrophy(LVH) and to explore the superposition effect of dyslipidemia combined with hypertension.Methods : Data on 9134 participants(53.5 ±10.3 years old) from the Northeast China Rural Cardiovascular Health Study(NCRCHS) were statistically analyzed. The blood lipid profile was measured by total cholesterol(TC), low-density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C), total glyceride(TG), and calculated nontraditional blood lipid indices including non-HDL-C, atherosclerosis index(AI), TC/HDL-C, and residual cholesterol(RC).Results : After the adjustment of age and gender, the odds ratios(ORs) of LVH in patients with hypertension, high LDL-C, high non-HDL-C, high AI, and high TC/HDL-C were 3.97(3.31– 4.76), 1.27(1.02– 1.59), 1.21(1.04– 1.39), 1.33(1.15– 1.53), and 1.42(1.22– 1.65), respectively. After full adjustment of potential confounding factors, high AI and TC/HDL-C were associated with LVH rather than traditional blood lipid indices.The combination of hypertension and nontraditional dyslipidemia(defined by high AI and TC/HDL-C) was associated with the highest risk of LVH, especially in participants under 45 years of age. The risk was more significant in men, 5.09-fold and 6.24-fold,respectively, compared with 3.66-fold and 4.01-fold in women.Conclusions : People with dyslipidemia defined by nontraditional blood lipid indices(high AI and high TC/HDL-C) and hypertension were more likely to develop LVH.
