Matrix inversion is a critical part in communication, signal processing and electromagnetic system. A flexible and scalable very long instruction word (VLIW) processor with clustered architecture is proposed for mat...Matrix inversion is a critical part in communication, signal processing and electromagnetic system. A flexible and scalable very long instruction word (VLIW) processor with clustered architecture is proposed for matrix inversion. A global register file (RF) is used to connect al the clusters. Two nearby clusters share a local register file. The instruction sets are also designed for the VLIW processor. Experimental results show that the proposed VLIW architecture takes only 45 latency to invert a 4 × 4 matrix when running at 150 MHz. The proposed design is roughly five times faster than the DSP solution in processing speed.展开更多
The ozone(O_(3))pollution in China drew lots of attention in recent years,and the Sichuan Basin(SCB)was one of the regions confronting worsening O_(3)pollution problem.Many previous studies have shown that regional tr...The ozone(O_(3))pollution in China drew lots of attention in recent years,and the Sichuan Basin(SCB)was one of the regions confronting worsening O_(3)pollution problem.Many previous studies have shown that regional transport is an important contributor to O_(3)pollution.However,very few features of the O_(3)profile during transport have been reported,especially in the border regions between different administrative divisions.In this study,we conducted tethered balloon soundings in SCB during the summer of 2020 and captured a nocturnal O_(3)transport event during the campaign.Vertically,the O_(3)transport occurred in the bottom of the residual layer,between 200 and 500 m above ground level.Horizontally,the transport pathway was directed from southeast to northwest based on the analysis of the wind field and air mass trajectories.The effect of transport in the residual layer on the surface O_(3)concentration was related to the spatial distribution of O_(3).For cities with high O_(3)concentrations in the upwind region,the transport process would bring clean air masses and abate pollution.For downwind lightly polluted cities,the transport process would slow down the decreasing or even increase the surface O_(3)concentration during the night.We provided observational facts on the profile features of a transboundary O_(3)transport event between two provincial administrative divisions,which implicated the importance of joint prevention and control measures.However,the sounding parameters were limited and the quantitative analysis was preliminary,more integrated,and thorough studies of this topic were called for in the future.展开更多
The concept of just noticeable difference (JND), which accounts for the visibility threshold (visual redundancy)of the human visual system,is useful in perceptionoriented signal processing systems.In this work,we pres...The concept of just noticeable difference (JND), which accounts for the visibility threshold (visual redundancy)of the human visual system,is useful in perceptionoriented signal processing systems.In this work,we present a comprehensive review of JND estimation technology.First, the visual mechanism and its corresponding computational modules are illustrated.These include luminance adaptation, contrast masking,pattern masking,and the contrast sensitivity function.Next,the existing pixel domain and subband domain YND models are presented and analyzed.Finally,the challenges associated with JND estimation are discussed.展开更多
Two channels of the Cloud Aerosol Polarimetric Imager,onboard the TanSat-Chinese carbon dioxide observation satellite,are designed to detect the polarization state of radiation reflected by the earth-atmosphere system...Two channels of the Cloud Aerosol Polarimetric Imager,onboard the TanSat-Chinese carbon dioxide observation satellite,are designed to detect the polarization state of radiation reflected by the earth-atmosphere system in a single-viewing angle.Aiming to understand how the earth and atmospheric parameters affect the polarization state of radiation,we conduct a sensitivity analysis of the polarized reflectance at the top of atmosphere(TOA)with respect to the aerosol microphysical parameters,atmospheric profiles,and surface polarization properties.It is found that(1)the TOA polarization reflectance at 0.66 lm is most sensitive to the real part of the aerosol complex refractive index,the mean radius of the fine mode aerosol particles,as well as atmospheric pressure and temperature profiles;(2)the TOA polarization reflectance at 1.64 lm is sensitive to the volume ratio between the coarse mode and fine mode particles as well,but it is not sensitive to atmospheric profiles;and(3)surface polarization properties have a relatively weak influence on the TOA polarization reflectance at both 0.66 and 1.64 lm.展开更多
The total column-averaged volume mixing ratio of atmospheric carbon dioxide(XCO2)has been retrieved with high spectral resolution solar absorption data obtained from ground-based Fourier transform spectrometer(FTS)mea...The total column-averaged volume mixing ratio of atmospheric carbon dioxide(XCO2)has been retrieved with high spectral resolution solar absorption data obtained from ground-based Fourier transform spectrometer(FTS)measurements at Xichong,a coastal site in the district of Shenzhen in southern China.Based on differential optical absorption spectroscopy(DOAS)theory,the XCO2was retrieved by finding the best match of observed high spectral resolution solar absorption data and monochromatic radiation transfer model calculations.The averaged XCO2in the whole observation period was about 394.9 ppm.The uncertainty of the retrieval was estimated to be 2.0 ppm(0.51%)by comparing retrievals at two bands.The preliminary results show that XCO2retrieved by this method can be used to validate satellite remote sensing of XCO2:展开更多
Background The visual system and its inherent functions undergo experience-dependent changes through the lifespan,enabling acquisition of new skills.Previous fMRI studies using tasks reported increased specialization ...Background The visual system and its inherent functions undergo experience-dependent changes through the lifespan,enabling acquisition of new skills.Previous fMRI studies using tasks reported increased specialization in a number of cortical regions subserving visual expertise.Although ample studies focused on representation of long-term visual expertise in the brain,i.e.in terms of year,monthly-based early-stage representation of visual expertise remains unstudied.Given that spontaneous neuronal oscillations actively encode previous experience,we propose brain representations in the resting state is fundamentally important.Objective The current study aimed to investigate how monthly-based early-stage visual expertise are represented in the resting state using the expertise model of radiologists.Methods In particular,we investigated the altered local clustering pattern of spontaneous brain activity using regional homogeneity(ReHo).A cohort group of radiology interns(n=22)after one-month training in X-ray department and matched laypersons(n=22)were recruited after rigorous behavioral assessment.Results The results showed higher ReHo in the right hippocampus(HIP)and the right ventral anterior temporal lobe(vATL)(corrected by Alphasim correction,P<0.05).Moreover,ReHo in the right HIP correlated with the number of cases reviewed during intern radiologists’training(corrected by Alphasim correction,P<0.05).Conclusions In sum,our results demonstrated that the early stage of visual expertise is more concerned with stabilizing visual feature and domain-specific knowledge into long-term memory.The results provided novel evidence regarding how early-stage visual expertise is represented in the resting brain,which help further elaborate how human visual expertise is acquired.We propose that our current study may provide novel ideas for developing new training protocols in medical schools.展开更多
Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently ...Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.展开更多
基金supported by the National Natural Science Foundation of China(6110015561227004+4 种基金613720716137213161201289)the Fundamental Research Funds of the Central Universities of China(K5051302096JB140207)
文摘Matrix inversion is a critical part in communication, signal processing and electromagnetic system. A flexible and scalable very long instruction word (VLIW) processor with clustered architecture is proposed for matrix inversion. A global register file (RF) is used to connect al the clusters. Two nearby clusters share a local register file. The instruction sets are also designed for the VLIW processor. Experimental results show that the proposed VLIW architecture takes only 45 latency to invert a 4 × 4 matrix when running at 150 MHz. The proposed design is roughly five times faster than the DSP solution in processing speed.
基金supported by the National Key R&D Program of China(Nos.2018YFC0214002 and 2018YFC0214001)the Key S&T Program of Sichuan Province(No.2018SZDZX0023)+1 种基金the National Natural Science Foundation of China(No.22076129)the Fundamental Research Funds for the Central Universities(Nos.YJ201871 and YJ201891)。
文摘The ozone(O_(3))pollution in China drew lots of attention in recent years,and the Sichuan Basin(SCB)was one of the regions confronting worsening O_(3)pollution problem.Many previous studies have shown that regional transport is an important contributor to O_(3)pollution.However,very few features of the O_(3)profile during transport have been reported,especially in the border regions between different administrative divisions.In this study,we conducted tethered balloon soundings in SCB during the summer of 2020 and captured a nocturnal O_(3)transport event during the campaign.Vertically,the O_(3)transport occurred in the bottom of the residual layer,between 200 and 500 m above ground level.Horizontally,the transport pathway was directed from southeast to northwest based on the analysis of the wind field and air mass trajectories.The effect of transport in the residual layer on the surface O_(3)concentration was related to the spatial distribution of O_(3).For cities with high O_(3)concentrations in the upwind region,the transport process would bring clean air masses and abate pollution.For downwind lightly polluted cities,the transport process would slow down the decreasing or even increase the surface O_(3)concentration during the night.We provided observational facts on the profile features of a transboundary O_(3)transport event between two provincial administrative divisions,which implicated the importance of joint prevention and control measures.However,the sounding parameters were limited and the quantitative analysis was preliminary,more integrated,and thorough studies of this topic were called for in the future.
基金the National Natural Science Foundation of China (Grant No.61401325)the Research Fund for the Doctoral Program of Higher Education (20130203130001)the Young Talent Fund of University Association for Science and Technology in Shaanxi (20150110).
文摘The concept of just noticeable difference (JND), which accounts for the visibility threshold (visual redundancy)of the human visual system,is useful in perceptionoriented signal processing systems.In this work,we present a comprehensive review of JND estimation technology.First, the visual mechanism and its corresponding computational modules are illustrated.These include luminance adaptation, contrast masking,pattern masking,and the contrast sensitivity function.Next,the existing pixel domain and subband domain YND models are presented and analyzed.Finally,the challenges associated with JND estimation are discussed.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05040000)the National High Technology Research and Development Program of China(SQ2010AA1221583001)the National Natural Science Foundation of China(40775002,41175020 and 41375008)
文摘Two channels of the Cloud Aerosol Polarimetric Imager,onboard the TanSat-Chinese carbon dioxide observation satellite,are designed to detect the polarization state of radiation reflected by the earth-atmosphere system in a single-viewing angle.Aiming to understand how the earth and atmospheric parameters affect the polarization state of radiation,we conduct a sensitivity analysis of the polarized reflectance at the top of atmosphere(TOA)with respect to the aerosol microphysical parameters,atmospheric profiles,and surface polarization properties.It is found that(1)the TOA polarization reflectance at 0.66 lm is most sensitive to the real part of the aerosol complex refractive index,the mean radius of the fine mode aerosol particles,as well as atmospheric pressure and temperature profiles;(2)the TOA polarization reflectance at 1.64 lm is sensitive to the volume ratio between the coarse mode and fine mode particles as well,but it is not sensitive to atmospheric profiles;and(3)surface polarization properties have a relatively weak influence on the TOA polarization reflectance at both 0.66 and 1.64 lm.
基金supported by the Chinese Academy of Sciences(XDA05040203)the National High-Tech R&D Program of China(SQ2010AA1221583001)+1 种基金the National Natural Science Foundation of China(40775002,41175020,and 41375008)the Climate Change Program of the Chinese Meteorological Administration(CCSF201351)
文摘The total column-averaged volume mixing ratio of atmospheric carbon dioxide(XCO2)has been retrieved with high spectral resolution solar absorption data obtained from ground-based Fourier transform spectrometer(FTS)measurements at Xichong,a coastal site in the district of Shenzhen in southern China.Based on differential optical absorption spectroscopy(DOAS)theory,the XCO2was retrieved by finding the best match of observed high spectral resolution solar absorption data and monochromatic radiation transfer model calculations.The averaged XCO2in the whole observation period was about 394.9 ppm.The uncertainty of the retrieval was estimated to be 2.0 ppm(0.51%)by comparing retrievals at two bands.The preliminary results show that XCO2retrieved by this method can be used to validate satellite remote sensing of XCO2:
基金This paper is supported by National Key R&D Program of China(Grant No.2022YFF1202400)the National Natural Science Foundation of China(U19B2030)the Science and Technology Projects of Xi’an,China(No.201809170CX11JC12).
文摘Background The visual system and its inherent functions undergo experience-dependent changes through the lifespan,enabling acquisition of new skills.Previous fMRI studies using tasks reported increased specialization in a number of cortical regions subserving visual expertise.Although ample studies focused on representation of long-term visual expertise in the brain,i.e.in terms of year,monthly-based early-stage representation of visual expertise remains unstudied.Given that spontaneous neuronal oscillations actively encode previous experience,we propose brain representations in the resting state is fundamentally important.Objective The current study aimed to investigate how monthly-based early-stage visual expertise are represented in the resting state using the expertise model of radiologists.Methods In particular,we investigated the altered local clustering pattern of spontaneous brain activity using regional homogeneity(ReHo).A cohort group of radiology interns(n=22)after one-month training in X-ray department and matched laypersons(n=22)were recruited after rigorous behavioral assessment.Results The results showed higher ReHo in the right hippocampus(HIP)and the right ventral anterior temporal lobe(vATL)(corrected by Alphasim correction,P<0.05).Moreover,ReHo in the right HIP correlated with the number of cases reviewed during intern radiologists’training(corrected by Alphasim correction,P<0.05).Conclusions In sum,our results demonstrated that the early stage of visual expertise is more concerned with stabilizing visual feature and domain-specific knowledge into long-term memory.The results provided novel evidence regarding how early-stage visual expertise is represented in the resting brain,which help further elaborate how human visual expertise is acquired.We propose that our current study may provide novel ideas for developing new training protocols in medical schools.
基金supported by the National Natural Science Foundation of China(No.21906108)the Fundamental Research Funds for the Central Universities(No.YJ201937)Chengdu Science and Technology Bureau(No.2020-YF09-00051-SN)
文摘Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.