A full automatic welding machine for spherical tanks' all position multi layer welds has been developed. This machine is mainly composed of a two dimension seam tracking system based on microcomputer's memor...A full automatic welding machine for spherical tanks' all position multi layer welds has been developed. This machine is mainly composed of a two dimension seam tracking system based on microcomputer's memory and a welding tractor as well as rail. The main features of the machine are: while welding the first layer of a seam, its microcomputer system can analyze and store the tracing information from a two dimension sensor, and control the welding head device to realize two dimension real time tracing; while welding the second layer up to the top layer of the seam, it can realize two dimension tracing based on the memorial data, automatically determine the layer number and continually sway the welding head. The welding test shows that the machine has good tracing and welding behavior, and is suitable for spherical tank's all position multi layer welds.展开更多
Fugitive dust is one of the well known problems in agriculture and it affects both humans and machine producing quality. Dust problems can seriously cause harmful diseases to workers and ruin expensive equipments. In ...Fugitive dust is one of the well known problems in agriculture and it affects both humans and machine producing quality. Dust problems can seriously cause harmful diseases to workers and ruin expensive equipments. In this study, a dust formation generated in open environment by vehicles was analyzed on unpaved roads. Formed dust was measured by calculating total forces on the PM10 （airborne particles smaller than 10 mm） of dust particles, such as air velocity, gravity forces and air turbulence generated by the moving vehicle. The water fogger nozzle discharge was measured to determine the approximate droplets quantity in the air. The foggers were used to suppress the generated dust in an open environment via installing a proposed automatic suppression system which opens automatically when vehicles pass under the system. The relationship between water droplet speed and ability of collecting fugitive dust showed that high air temperature above 40oC and wind speed above 10 m s-1 have negative effects on the system’s ability of collecting dust due to evaporation of small radius droplets and/or drifting water droplets away from the effective area. The overall system efficiency was found to be 85% and the proposed dust suppression system was found to be a satisfying solution for reducing fugitive dust hazards.展开更多
In this paper, a speech signal recovery algorithm is presented for a personalized voice command automatic recognition system in vehicle and restaurant environments. This novel algorithm is able to separate a mixed spe...In this paper, a speech signal recovery algorithm is presented for a personalized voice command automatic recognition system in vehicle and restaurant environments. This novel algorithm is able to separate a mixed speech source from multiple speakers, detect presence/absence of speakers by tracking the higher magnitude portion of speech power spectrum and adaptively suppress noises. An automatic speech recognition (ASR) process to deal with the multi-speaker task is designed and implemented. Evaluation tests have been carried out by using the speech da- tabase NOIZEUS and the experimental results show that the proposed algorithm achieves impressive performance improvements.展开更多
The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion m...The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.展开更多
采用基于三维智能射线追踪法(three-dimensional intelligent ray tracing method,3D-IRT)的GPS压制干扰预测方法,对城市场景低空空域的干扰效果进行预测。对地理环境进行预处理,将建筑物离散分割为大量单元并预先构建电磁波射线的传播...采用基于三维智能射线追踪法(three-dimensional intelligent ray tracing method,3D-IRT)的GPS压制干扰预测方法,对城市场景低空空域的干扰效果进行预测。对地理环境进行预处理,将建筑物离散分割为大量单元并预先构建电磁波射线的传播路径,以发射机为起点追踪所有单元,在接收点叠加计算所有射线的功率得到接收功率。结合干扰容限预测压制干扰的影响范围,并与主路径法的计算结果进行比较。结果表明,3D-IRT法可以反映城市场景中的电波传播特点,尤其当干扰源周围环境复杂时,计算结果更能反映电磁波传播的多径效应和小尺度衰落,预处理可以大大减小电波传播预测的计算量,相较于主路径法具有更高的计算精度。展开更多
文摘A full automatic welding machine for spherical tanks' all position multi layer welds has been developed. This machine is mainly composed of a two dimension seam tracking system based on microcomputer's memory and a welding tractor as well as rail. The main features of the machine are: while welding the first layer of a seam, its microcomputer system can analyze and store the tracing information from a two dimension sensor, and control the welding head device to realize two dimension real time tracing; while welding the second layer up to the top layer of the seam, it can realize two dimension tracing based on the memorial data, automatically determine the layer number and continually sway the welding head. The welding test shows that the machine has good tracing and welding behavior, and is suitable for spherical tank's all position multi layer welds.
基金funded by the Special Program on the S&T of China for the Pollution Control and Treatment of Water Bodies(2008ZX07421-001)the Foundamental Research Funds for the Central Universities, China
文摘Fugitive dust is one of the well known problems in agriculture and it affects both humans and machine producing quality. Dust problems can seriously cause harmful diseases to workers and ruin expensive equipments. In this study, a dust formation generated in open environment by vehicles was analyzed on unpaved roads. Formed dust was measured by calculating total forces on the PM10 （airborne particles smaller than 10 mm） of dust particles, such as air velocity, gravity forces and air turbulence generated by the moving vehicle. The water fogger nozzle discharge was measured to determine the approximate droplets quantity in the air. The foggers were used to suppress the generated dust in an open environment via installing a proposed automatic suppression system which opens automatically when vehicles pass under the system. The relationship between water droplet speed and ability of collecting fugitive dust showed that high air temperature above 40oC and wind speed above 10 m s-1 have negative effects on the system’s ability of collecting dust due to evaporation of small radius droplets and/or drifting water droplets away from the effective area. The overall system efficiency was found to be 85% and the proposed dust suppression system was found to be a satisfying solution for reducing fugitive dust hazards.
文摘In this paper, a speech signal recovery algorithm is presented for a personalized voice command automatic recognition system in vehicle and restaurant environments. This novel algorithm is able to separate a mixed speech source from multiple speakers, detect presence/absence of speakers by tracking the higher magnitude portion of speech power spectrum and adaptively suppress noises. An automatic speech recognition (ASR) process to deal with the multi-speaker task is designed and implemented. Evaluation tests have been carried out by using the speech da- tabase NOIZEUS and the experimental results show that the proposed algorithm achieves impressive performance improvements.
文摘The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.
文摘采用基于三维智能射线追踪法(three-dimensional intelligent ray tracing method,3D-IRT)的GPS压制干扰预测方法,对城市场景低空空域的干扰效果进行预测。对地理环境进行预处理,将建筑物离散分割为大量单元并预先构建电磁波射线的传播路径,以发射机为起点追踪所有单元,在接收点叠加计算所有射线的功率得到接收功率。结合干扰容限预测压制干扰的影响范围,并与主路径法的计算结果进行比较。结果表明,3D-IRT法可以反映城市场景中的电波传播特点,尤其当干扰源周围环境复杂时,计算结果更能反映电磁波传播的多径效应和小尺度衰落,预处理可以大大减小电波传播预测的计算量,相较于主路径法具有更高的计算精度。
