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Efficient matrix inversion based on VLIW architecture
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作者 Li Zhang Fu Li guangming shi 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第3期393-398,共6页
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
关键词 matrix inversion very long instruction word (VLIW) latency register file (RF) cluster.
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An observed nocturnal ozone transport event in the Sichuan Basin,Southwestern China
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作者 Ruyue Guo guangming shi +4 位作者 Dan Zhang Yang Chen Chao Peng Chongzhi Zhai Fumo Yang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2024年第4期10-18,共9页
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
关键词 OZONE Sichuan basin Transport event Vertical profile
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面向事件相机的轻量化脉冲识别网络 被引量:1
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作者 刘昭辛 吴金建 +1 位作者 石光明 赵庆行 《中国科学:信息科学》 CSCD 北大核心 2023年第7期1333-1347,共15页
事件相机是一种用脉冲表达信息的仿生成像传感器,具有高时域分辨率、高动态范围、低功耗和高速率等优势.由于事件驱动特性,传统人工神经网络(artificial neural networks,ANN)无法直接处理事件相机输出的脉冲信号.而脉冲神经网络(spikin... 事件相机是一种用脉冲表达信息的仿生成像传感器,具有高时域分辨率、高动态范围、低功耗和高速率等优势.由于事件驱动特性,传统人工神经网络(artificial neural networks,ANN)无法直接处理事件相机输出的脉冲信号.而脉冲神经网络(spiking neural network,SNN)作为一种神经形态计算方法,具有高时域分辨率及事件驱动的特性,这与事件相机高度契合.但是,深层脉冲神经网络需要消耗大量存储空间以及神经元计算资源,严重限制了其在边缘计算场景的部署.本文基于特征维度映射原理,提出面向嵌入式系统的轻量化脉冲神经网络,降低存储需求、提高运行效率并提高网络性能.首先,通过分析网络参数量与网络拟合功能间的关系,明确了约束脉冲神经网络能力的参数瓶颈问题.随后,基于低维特征提取–融合策略提出一种通用轻量化特征提取结构SpikeFire,该模块在保证感受野和特征维度等基本性质不变的前提下大幅减少了网络参数.此外,模拟脑神经元复杂连接特性,模块中采用跳层连接,这既增加多尺度信息提取又有助于深层次网络的优化.最后,将本文所提轻量化网络部署在嵌入式硬件中,开发出了事件驱动的成像识别一体化系统.实验表明,无论是在公开数据集还是自建真实场景和极端成像场景中,所提方法在保证识别性能的前提下大幅减少了参数量并提高运行速度. 展开更多
关键词 脉冲神经网络 事件相机 轻量化网络 特征融合 嵌入式硬件
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Survey of visual just noticeable difference estimation 被引量:2
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作者 Jinjian WU guangming shi Weisi LIN 《Frontiers of Computer Science》 SCIE EI CSCD 2019年第1期4-15,共12页
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
关键词 JUST noticeable DIFFERENCE human VISUAL system LUMINANCE adaptation CONTRAST MASKING pattern MASKING CONTRAST sensitivity function
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Sensitivity analysis of single-angle polarization reflectance observed by satellite 被引量:1
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作者 guangming shi Chengcai Li Tong Ren 《Chinese Science Bulletin》 SCIE EI CAS 2014年第14期1519-1528,共10页
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
关键词 敏感性分析 偏振反射 卫星观测 地球大气系统 气溶胶粒子 复数折射率 TOA 观测卫星
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Retrieval of column-averaged volume mixing ratio of CO_2 with ground-based high spectral resolution solar absorption 被引量:1
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作者 Jian Li Chengcai Li +6 位作者 Jietai Mao Dongwei Yang Dong Wang Lin Mei guangming shi Yefang Wang Xia Mao 《Chinese Science Bulletin》 SCIE EI CAS 2014年第14期1536-1540,共5页
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
关键词 高光谱分辨率 平均体积 二氧化碳 吸收塔 太阳能 混合比 检索 陆基
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Early stage of radiological expertise modulates resting-state local coherence in the inferior temporal lobe 被引量:1
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作者 Minghao Dong Peiming Zhang +9 位作者 Weilu Chai Xiaoyan Zhang Bihong TChen Hongmei Wang Jia Wu Chao Chen Yi Niu Jimin Liang guangming shi Chenwang Jin 《Psychoradiology》 2022年第4期199-206,共8页
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
关键词 visual expertise resting state fMRI RADIOLOGISTS inferior temporal cortex
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Characteristics of ambient volatile organic compounds during spring O_(3) pollution episode in Chengdu,China
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作者 Dongyang Chen Li Zhou +6 位作者 Chen Wang Hefan Liu Yang Qiu guangming shi Danlin Song Qinwen Tan Fumo Yang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2022年第4期115-125,共11页
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
关键词 Volatile organic compounds Ozone sensitivity Observation-based box model Source apportionments Chengdu
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