黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。...黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。本文从已发表文献中提取我国126个站点的1616个BC月监测数据,时间跨度为2000−2020年,对MERRA-2(Modern-Era Retrospective Analysis for Research and Applications,Version 2)和TAP(Tracking Air Pollution in China)的BC数据进行全面的精度验证和适用性评价。结果表明:①MERRA-2与TAP均低估了我国大气BC浓度,其中MERRA-2低估程度为8.13%,TAP低估程度为19.51%。TAP的大气BC浓度与地面站点监测数据的相关性〔R=0.62,模拟实测两倍因子(FAC2)=0.69〕高于MERRA-2(R=0.46,FAC2=0.58),MERRA-2的20年平均大气BC浓度(3.61μg/m^(3))更接近地面站点平均大气BC浓度(3.97μg/m^(3))。②MERRA-2和TAP的大气BC浓度在我国不同地区的精度存在较大差别,MERRA-2在我国华北和西南地区的精度优于TAP。两个数据集在西南地区都有较高的精度(R为0.68~0.84,FAC2为0.71~0.79),在华北地区精度均较低(R为0.41~0.48,FAC2为0.64~0.77)。③MERRA-2与TAP大气BC浓度在全国大部分地区呈显著正相关,其中,二者在四川省大气BC浓度差异(0.0045μg/m^(3))最小,在北京市差异(2.11μg/m^(3))最大。研究显示,MERRA-2有更长的时间跨度,而TAP更能准确表现大气BC浓度的空间分布,且二者在不同地区表现出较大差异。展开更多
Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Re...Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Republic of Congo.A total of fifty four water samples including thirty two samples from drilled water wells,ten samples from spade-sunk water wells,six samples from supplied tap water,four samples from a mine effluent and two samples from a river were collected from both localities in November and December 2017 and in January,February and March 2018.Then the samples were analyzed for their PTE contents by ICP-SF-MS(Inductively Coupled Plasma-Sector Field Mass Spectrometry).Twenty PTEs including aluminum,arsenic,barium,bismuth,cadmium,cesium,chromium,cobalt,copper,iron,lead,manganese,molybdenum,nickel,strontium,thallium,tungsten,uranium,vanadium and zinc were detected at various concentrations in each one of the samples.Many samples had concentrations and mean concentrations of PTE,such as arsenic,aluminum,cadmium,iron,lead,manganese and zinc,higher than the respective acceptable limits set for drinking water by the EU(European Union),the USEPA(United States Environmental Protection Agency),and the WHO(World Health Organization)standards.Most PTEs being deleterious to human health even at very low concentrations,people who use the groundwater,surface water and tap water to meet their water needs in both localities are at risk.展开更多
As an emerging environmental contaminant,antibiotic resistance genes(ARGs)in tap water have attracted great attention.Although studies have provided ARG profiles in tap water,research on their abundance levels,composi...As an emerging environmental contaminant,antibiotic resistance genes(ARGs)in tap water have attracted great attention.Although studies have provided ARG profiles in tap water,research on their abundance levels,composition characteristics,and potential threat is still insufficient.Here,9 household tap water samples were collected from the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)in China.Additionally,75 sets of environmental sample data(9 types)were downloaded from the public database.Metagenomics was then performed to explore the differences in the abundance and composition of ARGs.221 ARG subtypes consisting of 17 types were detected in tap water.Although the ARG abundance in tap water was not significantly different from that found in drinking water plants and reservoirs,their composition varied.In tap water samples,the three most abundant classes of resistance genes were multidrug,fosfomycin and MLS(macrolide-lincosamidestreptogramin)ARGs,and their corresponding subtypes ompR,fosX and macB were also the most abundant ARG subtypes.Regarding the potential mobility,vanS had the highest abundance on plasmids and viruses,but the absence of key genes rendered resistance to vancomycin ineffective.Generally,the majority of ARGs present in tap water were those that have not been assessed and are currently not listed as high-threat level ARG families based on the World Health Organization Guideline.Although the current potential threat to human health posed by ARGs in tap water is limited,with persistent transfer and accumulation,especially in pathogens,the potential danger to human health posed by ARGs should not be ignored.展开更多
An in-pixel histogramming time-to-digital converter(hTDC)based on octonary search and 4-tap phase detection is presented,aiming to improve frame rate while ensuring high precicion.The proposed hTDC is a 12-bit two-ste...An in-pixel histogramming time-to-digital converter(hTDC)based on octonary search and 4-tap phase detection is presented,aiming to improve frame rate while ensuring high precicion.The proposed hTDC is a 12-bit two-step converter consisting of a 6-bit coarse quantization and a 6-bit fine quantization,which supports a time resolution of 120 ps and multiphoton counting up to 2 GHz without a GHz reference frequency.The proposed hTDC is designed in 0.11μm CMOS process with an area consumption of 6900μm^(2).The data from a behavioral-level model is imported into the designed hTDC circuit for simulation verification.The post-simulation results show that the proposed hTDC achieves 0.8%depth precision in 9 m range for short-range system design specifications and 0.2%depth precision in 48 m range for long-range system design specifications.Under 30×10^(3) lux background light conditions,the proposed hTDC can be used for SPAD-based flash LiDAR sensor to achieve a frame rate to 40 fps with 200 ps resolution in 9 m range.展开更多
The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the paramet...The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent.展开更多
The continuous operation of On-Load Tap-Changers (OLTC) is essential for maintaining stable voltage levels in power transmission and distribution systems. Timely fault detection in OLTC is essential for preventing maj...The continuous operation of On-Load Tap-Changers (OLTC) is essential for maintaining stable voltage levels in power transmission and distribution systems. Timely fault detection in OLTC is essential for preventing major failures and ensuring the reliability of the electrical grid. This research paper proposes an innovative approach that combines voiceprint detection using MATLAB analysis for online fault monitoring of OLTC. By leveraging advanced signal processing techniques and machine learning algorithms in MATLAB, the proposed method accurately detects faults in OLTC, providing real-time monitoring and proactive maintenance strategies.展开更多
文摘黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。本文从已发表文献中提取我国126个站点的1616个BC月监测数据,时间跨度为2000−2020年,对MERRA-2(Modern-Era Retrospective Analysis for Research and Applications,Version 2)和TAP(Tracking Air Pollution in China)的BC数据进行全面的精度验证和适用性评价。结果表明:①MERRA-2与TAP均低估了我国大气BC浓度,其中MERRA-2低估程度为8.13%,TAP低估程度为19.51%。TAP的大气BC浓度与地面站点监测数据的相关性〔R=0.62,模拟实测两倍因子(FAC2)=0.69〕高于MERRA-2(R=0.46,FAC2=0.58),MERRA-2的20年平均大气BC浓度(3.61μg/m^(3))更接近地面站点平均大气BC浓度(3.97μg/m^(3))。②MERRA-2和TAP的大气BC浓度在我国不同地区的精度存在较大差别,MERRA-2在我国华北和西南地区的精度优于TAP。两个数据集在西南地区都有较高的精度(R为0.68~0.84,FAC2为0.71~0.79),在华北地区精度均较低(R为0.41~0.48,FAC2为0.64~0.77)。③MERRA-2与TAP大气BC浓度在全国大部分地区呈显著正相关,其中,二者在四川省大气BC浓度差异(0.0045μg/m^(3))最小,在北京市差异(2.11μg/m^(3))最大。研究显示,MERRA-2有更长的时间跨度,而TAP更能准确表现大气BC浓度的空间分布,且二者在不同地区表现出较大差异。
文摘Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Republic of Congo.A total of fifty four water samples including thirty two samples from drilled water wells,ten samples from spade-sunk water wells,six samples from supplied tap water,four samples from a mine effluent and two samples from a river were collected from both localities in November and December 2017 and in January,February and March 2018.Then the samples were analyzed for their PTE contents by ICP-SF-MS(Inductively Coupled Plasma-Sector Field Mass Spectrometry).Twenty PTEs including aluminum,arsenic,barium,bismuth,cadmium,cesium,chromium,cobalt,copper,iron,lead,manganese,molybdenum,nickel,strontium,thallium,tungsten,uranium,vanadium and zinc were detected at various concentrations in each one of the samples.Many samples had concentrations and mean concentrations of PTE,such as arsenic,aluminum,cadmium,iron,lead,manganese and zinc,higher than the respective acceptable limits set for drinking water by the EU(European Union),the USEPA(United States Environmental Protection Agency),and the WHO(World Health Organization)standards.Most PTEs being deleterious to human health even at very low concentrations,people who use the groundwater,surface water and tap water to meet their water needs in both localities are at risk.
基金supported by the National Key R&D Program of China(No.2022YFE0103200)the Hubei Provincial Natural Science Foundation of China(No.2021CFB016)the National Natural Science Foundation of China(No.52100217).
文摘As an emerging environmental contaminant,antibiotic resistance genes(ARGs)in tap water have attracted great attention.Although studies have provided ARG profiles in tap water,research on their abundance levels,composition characteristics,and potential threat is still insufficient.Here,9 household tap water samples were collected from the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)in China.Additionally,75 sets of environmental sample data(9 types)were downloaded from the public database.Metagenomics was then performed to explore the differences in the abundance and composition of ARGs.221 ARG subtypes consisting of 17 types were detected in tap water.Although the ARG abundance in tap water was not significantly different from that found in drinking water plants and reservoirs,their composition varied.In tap water samples,the three most abundant classes of resistance genes were multidrug,fosfomycin and MLS(macrolide-lincosamidestreptogramin)ARGs,and their corresponding subtypes ompR,fosX and macB were also the most abundant ARG subtypes.Regarding the potential mobility,vanS had the highest abundance on plasmids and viruses,but the absence of key genes rendered resistance to vancomycin ineffective.Generally,the majority of ARGs present in tap water were those that have not been assessed and are currently not listed as high-threat level ARG families based on the World Health Organization Guideline.Although the current potential threat to human health posed by ARGs in tap water is limited,with persistent transfer and accumulation,especially in pathogens,the potential danger to human health posed by ARGs should not be ignored.
基金National Key Research and Development Program of China(2022YFB2804401)。
文摘An in-pixel histogramming time-to-digital converter(hTDC)based on octonary search and 4-tap phase detection is presented,aiming to improve frame rate while ensuring high precicion.The proposed hTDC is a 12-bit two-step converter consisting of a 6-bit coarse quantization and a 6-bit fine quantization,which supports a time resolution of 120 ps and multiphoton counting up to 2 GHz without a GHz reference frequency.The proposed hTDC is designed in 0.11μm CMOS process with an area consumption of 6900μm^(2).The data from a behavioral-level model is imported into the designed hTDC circuit for simulation verification.The post-simulation results show that the proposed hTDC achieves 0.8%depth precision in 9 m range for short-range system design specifications and 0.2%depth precision in 48 m range for long-range system design specifications.Under 30×10^(3) lux background light conditions,the proposed hTDC can be used for SPAD-based flash LiDAR sensor to achieve a frame rate to 40 fps with 200 ps resolution in 9 m range.
文摘The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent.
文摘The continuous operation of On-Load Tap-Changers (OLTC) is essential for maintaining stable voltage levels in power transmission and distribution systems. Timely fault detection in OLTC is essential for preventing major failures and ensuring the reliability of the electrical grid. This research paper proposes an innovative approach that combines voiceprint detection using MATLAB analysis for online fault monitoring of OLTC. By leveraging advanced signal processing techniques and machine learning algorithms in MATLAB, the proposed method accurately detects faults in OLTC, providing real-time monitoring and proactive maintenance strategies.
