In order to obtain the optimized aircraft design concept which meets the increasingly complex operation environment at the conceptual design stage,System-of-systems(So S)engineering must be considered.This paper propo...In order to obtain the optimized aircraft design concept which meets the increasingly complex operation environment at the conceptual design stage,System-of-systems(So S)engineering must be considered.This paper proposes a novel optimization method for the design of aircraft Mission Success Space(MSS)based on Gaussian fitting and Genetic Algorithm(GA)in the So S area.First,the concepts in the design and evaluation of MSS are summarized to introduce the Contribution to System-of-Systems(CSS)by using a conventional effectiveness index,Mission Success Rate(MSR).Then,the mathematic modelling of Gaussian fitting technique is noted as the basis of the optimization work.After that,the proposed optimal MSS design is illustrated by the multiobjective optimization process where GA acts as the search tool to find the best solution(via Pareto front).In the case study,a simulation system of penetration mission was built.The simulation results are collected and then processed by two MSS design schemes(contour and neural network)giving the initial variable space to GA optimization.Based on that,the proposed optimization method is implemented under both schemes whose optimal solutions are compared to obtain the final best design in the case study.展开更多
The energy distribution model of motion blurred star point is analyzed.The distribution of the star point approximates to a two-dimensional(2 D) Gaussian distribution under degeneration.Two multi-parameter nonlinear G...The energy distribution model of motion blurred star point is analyzed.The distribution of the star point approximates to a two-dimensional(2 D) Gaussian distribution under degeneration.Two multi-parameter nonlinear Gaussian fitting methods(GFMs) are proposed,and the relationship between fitting parameters and motion blur parameters is analyzed.Estimation of the parameters of motion blur by fitting parameters is calculated to realize the error compensation of the motion blur.The simulation results show the effectiveness and accuracy.展开更多
A slight uneven settlement of the foundation may cause the wind turbine to shake,tilt,or even collapse,so it is increasingly necessary to realize remote condition monitoring of the foundations.At present,the wind turb...A slight uneven settlement of the foundation may cause the wind turbine to shake,tilt,or even collapse,so it is increasingly necessary to realize remote condition monitoring of the foundations.At present,the wind turbine foundation monitoring system is incomplete.The current monitoring research of the tower foundation is mainly of contact measurements,using acceleration sensors and static-level sensors for monitoring multiple reference points.Such monitoring methods will face some disadvantages,such as the complexity of monitoring deployment,the cost of manpower,and the load effect on the tower structure.To solve above issues,this paper aims to investigate wind turbine tower foundation variation dynamic monitoring based on machine vision.Machine vision monitoring is a kind of noncontact measurement,which helps to realize comprehensive diagnosis of early foundation uneven settlement and loose faults.The FEA model is firstly investigated as the theoretical foundation to investigate the dynamics of the tower foundation.Second,the Gaussian-based vibration detection is adopted by tracking the tower edge points.Finally,a tower structure with distributed foundation support is tested.The modal parameters obtained from the visual measurement are compared with those from the accelerometer,proving the vision method can effectively monitor the issues with tower foundation changes.展开更多
Based on the Eigen and Crow-Kimura models with a single-peak fitness landscape, we propose the fitness values of all sequence types to be Gausslan distributed random variables to incorporate the effects of the fluctua...Based on the Eigen and Crow-Kimura models with a single-peak fitness landscape, we propose the fitness values of all sequence types to be Gausslan distributed random variables to incorporate the effects of the fluctuations of the fitness landscapes （noise of environments） and investigate the concentration distribution and error threshold of quasispecies by performing an ensemble average within this theoretical framework. We find that a small fluctuation of the fitness landscape causes only a slight change in the concentration distribution and error threshold, which implies that the error threshold is stable against small perturbations. However, for a sizable fluctuation, quite different from the previous deterministic models, our statistical results show that the transition from quasi-species to error catastrophe is not so sharp, indicating that the error threshold is located within a certain range and has a shift toward a larger value. Our results are qualitatively in agreement with the experimental data and provide a new implication for antiviral strategies.展开更多
A large number of logistics operations are needed to transport fabric rolls and dye barrels to different positions in printing and dyeing plants, and increasing labor cost is making it difficult for plants to recruit ...A large number of logistics operations are needed to transport fabric rolls and dye barrels to different positions in printing and dyeing plants, and increasing labor cost is making it difficult for plants to recruit workers to complete manual operations. Artificial intelligence and robotics, which are rapidly evolving, offer potential solutions to this problem. In this paper, a navigation method dedicated to solving the issues of the inability to pass smoothly at corners in practice and local obstacle avoidance is presented. In the system, a Gaussian fitting smoothing rapid exploration random tree star-smart(GFS RRT^(*)-Smart) algorithm is proposed for global path planning and enhances the performance when the robot makes a sharp turn around corners. In local obstacle avoidance, a deep reinforcement learning determiner mixed actor critic(MAC) algorithm is used for obstacle avoidance decisions. The navigation system is implemented in a scaled-down simulation factory.展开更多
Copper-doped ZnS （ZnS：Cu） nanocrystals are synthesized by the sol-gel method. The average size of the ZnS：Cu nanocrystals is 3.1 nm. The x-ray diffraction indicates that increasing the Cu-dopant concentration resu...Copper-doped ZnS （ZnS：Cu） nanocrystals are synthesized by the sol-gel method. The average size of the ZnS：Cu nanocrystals is 3.1 nm. The x-ray diffraction indicates that increasing the Cu-dopant concentration results in a large shift in the diffraction angle. The effects of the dopant concentration, the reactant ratio, and aging temperature on the optical properties of the ZnS：Cu nanocrystals are also investigated. The fluorescence emission mechanism is analyzed by peak deconvolution using Gaussian functions. We find that the emission of the ZnS：Cu nanocrystal is composed of different luminescence centers at 430, 470, 490, 526, and 560 nm. The origins of these emissions are discussed and demonstrated by controlled experiments.展开更多
Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can ...Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ...展开更多
Green apple targets are difficult to identify for having similar color with backgrounds such as leaves.The primary goal of this study was to detect green apples in natural scenes by applying saliency detection and Gau...Green apple targets are difficult to identify for having similar color with backgrounds such as leaves.The primary goal of this study was to detect green apples in natural scenes by applying saliency detection and Gaussian curve fitting algorithm.Firstly,the image was represented as a close-loop graph with superpixels as nodes.These nodes were ranked based on the similarity to background and foreground queries to generate the final saliency map.Secondly,Gaussian curve fitting was carried out to fit the V-component in YUV color space in salient areas,and a threshold was selected to binarize the image.To verify the validity of the proposed algorithm,55 images were selected and compared with the common used image segmentation algorithms such as k-means clustering algorithm and FCM(Fuzzy C-means clustering algorithm).Four parameters including recognition ratio,FPR(false positive rate),FNR(false negative rate)and FDR(false detection rate)were used to evaluate the results,which were 91.84%,1.36%,8.16%and 4.22%,respectively.The results indicated that it was effective and feasible to apply this method to the detection of green apples in nature scenes.展开更多
Inelastic incoherent neutron scattering spectra of D2O high-density amorphous （hda） ice, ice-Ⅷ and ice-Ⅱ mixed with small amount of H2O （（5%） have been measured recently on high-energy transfer spectrometer at ...Inelastic incoherent neutron scattering spectra of D2O high-density amorphous （hda） ice, ice-Ⅷ and ice-Ⅱ mixed with small amount of H2O （（5%） have been measured recently on high-energy transfer spectrometer at Rutherford Appleton Laboratory （UK）. The hydrogen atom on D2O ice lattices has three distinguished vibrational modes, two bending at low frequencies and one stretching at high frequencies, and their frequencies are slightly different for different phases of ice. It was found that the lower one of the bending modes is located at -95 meⅤ for hda-ice, at -95 meⅤ for ice-Ⅷ and at -96 meⅤ for ice-Ⅱ and they are all lower than the value of 104 meⅤ for ice-Ih. It was also measured that the O-D and O-H covalent bond stretching modes of ice-Ⅷ are at -315 and -425 meⅤ, ice-Ⅱ at 307 and -415 meⅤ, hda-ice at 312 and -418 meⅤ, respectively. They are significantly higher than the values of ice-Ih at -299 and -406 meⅤ, respectively.展开更多
This paper presents a novel design method of the Mission Success Space(MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the...This paper presents a novel design method of the Mission Success Space(MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the success by conventional mission effectiveness with regards to the aircraft capabilities. This space is created by the Mission Success Function(MSF) and the original Effectiveness Index Space(EIS) where empirical equations are usually assumed to be MSFs. Based on this MSS concept, this paper firstly defines the MSS-based evaluation, then further summarizes the evaluation process of the Contribution to System-of-Systems(CSS). More importantly, based on the thought of Inverse Design(ID), a new design method of MSF is presented comprehensively analyzing aircraft's CSS in a combat mission without using any empirical MSF. The definition of MSS based ID is given and the design procedure is sequentially introduced. Two different confrontation cases are depicted with many details as the simulation validation: Air-to-ground and Penetration. There are two design variables considered for designing MSS in the latter case while only one for the former. However, in both cases, the best design is given by evaluating the Gaussian fitting performance of CSS.展开更多
A topographic parameter inversion method based on laser altimetry is developed in this paper, which can be used to deduce the surface vertical profile and retrieve the topographic parameters within the laser footprint...A topographic parameter inversion method based on laser altimetry is developed in this paper, which can be used to deduce the surface vertical profile and retrieve the topographic parameters within the laser footprints by analyzing and simulating return waveforms. This method comprises three steps. The first step is to build the numerical models for the whole measuring procedure of laser altimetry, construct digital elevation models for surfaces with different topographic parameters, and calculate return waveforms. The second step is to analyze the simulated return waveforms to obtain their characteristics parameters, summarize the effects of the topographic parameter variations on the characteristic parameters of simulated return waveforms, and analyze the observed return waveforms of laser altimeters to acquire their characteristic parameters at the same time. The last step is to match the characteristic parameters of the simulated and observed return waveforms, and deduce the topographic parameters within the laser footprint. This method can be used to retrieve the topographic parameters within the laser footprint from the observed return waveforms of spaceborne laser altimeters and to get knowledge about the surface altitude distribution within the laser footprint other than only getting the height of the surface encountered firstly by the laser beam, which extends laser altimeters' function and makes them more like radars.展开更多
Walking-induced fluctuations have a significant influence on indoor airflow and pollutant dispersion.This study developed a method to quantify the robustness of ventilation systems in the control of walking-induced fl...Walking-induced fluctuations have a significant influence on indoor airflow and pollutant dispersion.This study developed a method to quantify the robustness of ventilation systems in the control of walking-induced fluctuation control.Experiments were conducted in a full-scale chamber with four different kinds of ventilation systems:ceiling supply and side return(CS),ceiling supply and ceiling return(CC),side supply and ceiling return(SC),and side supply and side return(SS).The measured temperature,flow and pollutant field data was(1)denoised by FFT filtering or wavelet transform;(2)fitted by a Gaussian function;(3)feature-extracted for the range and time scale disturbance;and then(4)used to calculate the range scale and time scale robustness for different ventilation systems with dimensionless equations developed in this study.The selection processes for FFT filtering and wavelet transform,FFT filter cut-off frequency,wavelet function,and decomposition layers are also discussed,as well as the threshold for wavelet denoising,which can be adjusted accordingly if the walking frequency or sampling frequency differs from that in other studies.The results show that for the flow and pollutant fields,the use of a ventilation system can increase the range scale robustness by 19.7%-39.4% and 10.0%-38.8%,respectively;and the SS system was 7.0%-25.7% more robust than the other three ventilation systems.However,all four kinds of ventilation systems had a very limited effect in controlling the time scale disturbance.展开更多
Background Liquid xenon time projection chamber(LXe TPC)is widely used in high-energy physics experiments such as particle detection and neutrino(or neutrinoless)double beta decay.The charge readout accuracy of the LX...Background Liquid xenon time projection chamber(LXe TPC)is widely used in high-energy physics experiments such as particle detection and neutrino(or neutrinoless)double beta decay.The charge readout accuracy of the LXeTPCdirectly affects the measurement results and success of the experiments.Because liquid xenon needs to maintain a cryogenic temperature between 162 and 165 K at atmospheric pressure,the charge generated in the LXe TPC always needs to be read out in the cryogenic environment for minimizing the input capacitance,which has effect in determining the output noise of the charge amplifier.Purpose Design a charge readout electronics system applicable to LXe TPC and research a data analysis method to get the exact amount of charge by analyzing the waveform at that output of the designed electronics system.Methods Design a multi-channel charge-reading application specific integrated circuit(ASIC)that can operate in the cryogenic environment.The signals and power supply of the ASIC are connected to an electronics system at room temperature through micro-coaxial cables.The electronics at room temperature complete the sampling of the ASIC output.A data acquisition device receives the sampled waveform data and calculates the charge measurement resolution by Gaussian fitting.Results The designed ASIC and selected micro-coaxial cable can work in stable condition under the cryogenic environment of 165 K.The analyzed integral nonlinearity of the charge measurement of the chip is 0.83%in the range from 1 to 50 fC,and the charge measurement resolution of the chip is lower than 900 e−RMS.Conclusion In this paper,a preliminary study of the charge readout method based on the system structure of self-developed ASIC,micro-coaxial cable,and data readout electronics is completed for LXe TPC.The system test results indicate that the designed ASIC can work normally in the cryogenic temperature of 165 K with a high dynamic range and good linearity of the charge measurement.Further work can be done to reduce the charge measurement resolution of the system to 200 e−RMS.展开更多
文摘In order to obtain the optimized aircraft design concept which meets the increasingly complex operation environment at the conceptual design stage,System-of-systems(So S)engineering must be considered.This paper proposes a novel optimization method for the design of aircraft Mission Success Space(MSS)based on Gaussian fitting and Genetic Algorithm(GA)in the So S area.First,the concepts in the design and evaluation of MSS are summarized to introduce the Contribution to System-of-Systems(CSS)by using a conventional effectiveness index,Mission Success Rate(MSR).Then,the mathematic modelling of Gaussian fitting technique is noted as the basis of the optimization work.After that,the proposed optimal MSS design is illustrated by the multiobjective optimization process where GA acts as the search tool to find the best solution(via Pareto front).In the case study,a simulation system of penetration mission was built.The simulation results are collected and then processed by two MSS design schemes(contour and neural network)giving the initial variable space to GA optimization.Based on that,the proposed optimization method is implemented under both schemes whose optimal solutions are compared to obtain the final best design in the case study.
文摘The energy distribution model of motion blurred star point is analyzed.The distribution of the star point approximates to a two-dimensional(2 D) Gaussian distribution under degeneration.Two multi-parameter nonlinear Gaussian fitting methods(GFMs) are proposed,and the relationship between fitting parameters and motion blur parameters is analyzed.Estimation of the parameters of motion blur by fitting parameters is calculated to realize the error compensation of the motion blur.The simulation results show the effectiveness and accuracy.
基金the support of the National Natural Science Foundation of China(NSFC)(62076029)Guangdong provincial base platforms and major scientific research project:Research on Remote Large Facility Condition Monitoring Method Based on Motion Amplification(ZX-2021-040)+1 种基金Major Scientific and Technological Project in the Inner Mongolia Autonomous Region(2023YFSW0003)the Guangdong Basic and Applied Basic Research Fund Offshore Wind Power Scheme-General Project under Grant 2022A1515240042.
文摘A slight uneven settlement of the foundation may cause the wind turbine to shake,tilt,or even collapse,so it is increasingly necessary to realize remote condition monitoring of the foundations.At present,the wind turbine foundation monitoring system is incomplete.The current monitoring research of the tower foundation is mainly of contact measurements,using acceleration sensors and static-level sensors for monitoring multiple reference points.Such monitoring methods will face some disadvantages,such as the complexity of monitoring deployment,the cost of manpower,and the load effect on the tower structure.To solve above issues,this paper aims to investigate wind turbine tower foundation variation dynamic monitoring based on machine vision.Machine vision monitoring is a kind of noncontact measurement,which helps to realize comprehensive diagnosis of early foundation uneven settlement and loose faults.The FEA model is firstly investigated as the theoretical foundation to investigate the dynamics of the tower foundation.Second,the Gaussian-based vibration detection is adopted by tracking the tower edge points.Finally,a tower structure with distributed foundation support is tested.The modal parameters obtained from the visual measurement are compared with those from the accelerometer,proving the vision method can effectively monitor the issues with tower foundation changes.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10475008, 10675170, and 10435020, and the Department of Nuclear Physics of China Institute of Atomic Energy under Grant Nos. 11SZZ-200501 and 11SZZ-200601
文摘Based on the Eigen and Crow-Kimura models with a single-peak fitness landscape, we propose the fitness values of all sequence types to be Gausslan distributed random variables to incorporate the effects of the fluctuations of the fitness landscapes （noise of environments） and investigate the concentration distribution and error threshold of quasispecies by performing an ensemble average within this theoretical framework. We find that a small fluctuation of the fitness landscape causes only a slight change in the concentration distribution and error threshold, which implies that the error threshold is stable against small perturbations. However, for a sizable fluctuation, quite different from the previous deterministic models, our statistical results show that the transition from quasi-species to error catastrophe is not so sharp, indicating that the error threshold is located within a certain range and has a shift toward a larger value. Our results are qualitatively in agreement with the experimental data and provide a new implication for antiviral strategies.
基金National Natural Science Foundation of China (No.61903078)。
文摘A large number of logistics operations are needed to transport fabric rolls and dye barrels to different positions in printing and dyeing plants, and increasing labor cost is making it difficult for plants to recruit workers to complete manual operations. Artificial intelligence and robotics, which are rapidly evolving, offer potential solutions to this problem. In this paper, a navigation method dedicated to solving the issues of the inability to pass smoothly at corners in practice and local obstacle avoidance is presented. In the system, a Gaussian fitting smoothing rapid exploration random tree star-smart(GFS RRT^(*)-Smart) algorithm is proposed for global path planning and enhances the performance when the robot makes a sharp turn around corners. In local obstacle avoidance, a deep reinforcement learning determiner mixed actor critic(MAC) algorithm is used for obstacle avoidance decisions. The navigation system is implemented in a scaled-down simulation factory.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61205193,61204065,and 61307045)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20112216120005)the Developing Project of Science and Technology of Jilin Province,China(Grant Nos.201201116,20140520107JH,and 20140204025GX)
文摘Copper-doped ZnS （ZnS：Cu） nanocrystals are synthesized by the sol-gel method. The average size of the ZnS：Cu nanocrystals is 3.1 nm. The x-ray diffraction indicates that increasing the Cu-dopant concentration results in a large shift in the diffraction angle. The effects of the dopant concentration, the reactant ratio, and aging temperature on the optical properties of the ZnS：Cu nanocrystals are also investigated. The fluorescence emission mechanism is analyzed by peak deconvolution using Gaussian functions. We find that the emission of the ZnS：Cu nanocrystal is composed of different luminescence centers at 430, 470, 490, 526, and 560 nm. The origins of these emissions are discussed and demonstrated by controlled experiments.
基金Supported by Major State Basic Research Program of China("973"Program,No.2010CB327800)Research Fund for Doctoral Program of Higher Education of China(No.20090032110053)New Teacher Research Fund for Doctoral Program of Higher Education of China (No.200800561022)
文摘Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ...
基金This study was supported by the National High Technology Research and Development Program of China(“863”Program)(No.2013AA10230402)Agricultural science and technology project of Shaanxi Province(No.2016NY-157)Fundamental Research Funds Central Universities(2452016077).
文摘Green apple targets are difficult to identify for having similar color with backgrounds such as leaves.The primary goal of this study was to detect green apples in natural scenes by applying saliency detection and Gaussian curve fitting algorithm.Firstly,the image was represented as a close-loop graph with superpixels as nodes.These nodes were ranked based on the similarity to background and foreground queries to generate the final saliency map.Secondly,Gaussian curve fitting was carried out to fit the V-component in YUV color space in salient areas,and a threshold was selected to binarize the image.To verify the validity of the proposed algorithm,55 images were selected and compared with the common used image segmentation algorithms such as k-means clustering algorithm and FCM(Fuzzy C-means clustering algorithm).Four parameters including recognition ratio,FPR(false positive rate),FNR(false negative rate)and FDR(false detection rate)were used to evaluate the results,which were 91.84%,1.36%,8.16%and 4.22%,respectively.The results indicated that it was effective and feasible to apply this method to the detection of green apples in nature scenes.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10274034 and 10474085）, and the Scientific Research Foundation for the Returned 0verseas Chinese Scholars, State Education Ministry, China.
文摘Inelastic incoherent neutron scattering spectra of D2O high-density amorphous （hda） ice, ice-Ⅷ and ice-Ⅱ mixed with small amount of H2O （（5%） have been measured recently on high-energy transfer spectrometer at Rutherford Appleton Laboratory （UK）. The hydrogen atom on D2O ice lattices has three distinguished vibrational modes, two bending at low frequencies and one stretching at high frequencies, and their frequencies are slightly different for different phases of ice. It was found that the lower one of the bending modes is located at -95 meⅤ for hda-ice, at -95 meⅤ for ice-Ⅷ and at -96 meⅤ for ice-Ⅱ and they are all lower than the value of 104 meⅤ for ice-Ih. It was also measured that the O-D and O-H covalent bond stretching modes of ice-Ⅷ are at -315 and -425 meⅤ, ice-Ⅱ at 307 and -415 meⅤ, hda-ice at 312 and -418 meⅤ, respectively. They are significantly higher than the values of ice-Ih at -299 and -406 meⅤ, respectively.
文摘This paper presents a novel design method of the Mission Success Space(MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the success by conventional mission effectiveness with regards to the aircraft capabilities. This space is created by the Mission Success Function(MSF) and the original Effectiveness Index Space(EIS) where empirical equations are usually assumed to be MSFs. Based on this MSS concept, this paper firstly defines the MSS-based evaluation, then further summarizes the evaluation process of the Contribution to System-of-Systems(CSS). More importantly, based on the thought of Inverse Design(ID), a new design method of MSF is presented comprehensively analyzing aircraft's CSS in a combat mission without using any empirical MSF. The definition of MSS based ID is given and the design procedure is sequentially introduced. Two different confrontation cases are depicted with many details as the simulation validation: Air-to-ground and Penetration. There are two design variables considered for designing MSS in the latter case while only one for the former. However, in both cases, the best design is given by evaluating the Gaussian fitting performance of CSS.
基金supported by the National Hi-Tech Research and Development Program of China (Grant No. 2007AA12Z177)
文摘A topographic parameter inversion method based on laser altimetry is developed in this paper, which can be used to deduce the surface vertical profile and retrieve the topographic parameters within the laser footprints by analyzing and simulating return waveforms. This method comprises three steps. The first step is to build the numerical models for the whole measuring procedure of laser altimetry, construct digital elevation models for surfaces with different topographic parameters, and calculate return waveforms. The second step is to analyze the simulated return waveforms to obtain their characteristics parameters, summarize the effects of the topographic parameter variations on the characteristic parameters of simulated return waveforms, and analyze the observed return waveforms of laser altimeters to acquire their characteristic parameters at the same time. The last step is to match the characteristic parameters of the simulated and observed return waveforms, and deduce the topographic parameters within the laser footprint. This method can be used to retrieve the topographic parameters within the laser footprint from the observed return waveforms of spaceborne laser altimeters and to get knowledge about the surface altitude distribution within the laser footprint other than only getting the height of the surface encountered firstly by the laser beam, which extends laser altimeters' function and makes them more like radars.
基金This study was supported by the National Natural Science Foundation of China(No.52108075)Natural Science Foundation of Hebei Province,China(No.E2020202147)+2 种基金S&T Program of Hebei(No.216Z4502G)Fundamental Research Funds of Hebei University of Technology(No.JBKYTD2003)Hebei Province Funding Project for Returned Scholars,China(No.C20190507).
文摘Walking-induced fluctuations have a significant influence on indoor airflow and pollutant dispersion.This study developed a method to quantify the robustness of ventilation systems in the control of walking-induced fluctuation control.Experiments were conducted in a full-scale chamber with four different kinds of ventilation systems:ceiling supply and side return(CS),ceiling supply and ceiling return(CC),side supply and ceiling return(SC),and side supply and side return(SS).The measured temperature,flow and pollutant field data was(1)denoised by FFT filtering or wavelet transform;(2)fitted by a Gaussian function;(3)feature-extracted for the range and time scale disturbance;and then(4)used to calculate the range scale and time scale robustness for different ventilation systems with dimensionless equations developed in this study.The selection processes for FFT filtering and wavelet transform,FFT filter cut-off frequency,wavelet function,and decomposition layers are also discussed,as well as the threshold for wavelet denoising,which can be adjusted accordingly if the walking frequency or sampling frequency differs from that in other studies.The results show that for the flow and pollutant fields,the use of a ventilation system can increase the range scale robustness by 19.7%-39.4% and 10.0%-38.8%,respectively;and the SS system was 7.0%-25.7% more robust than the other three ventilation systems.However,all four kinds of ventilation systems had a very limited effect in controlling the time scale disturbance.
基金a Grant from theNational Natural Science Foundation of China(No.11820101005).
文摘Background Liquid xenon time projection chamber(LXe TPC)is widely used in high-energy physics experiments such as particle detection and neutrino(or neutrinoless)double beta decay.The charge readout accuracy of the LXeTPCdirectly affects the measurement results and success of the experiments.Because liquid xenon needs to maintain a cryogenic temperature between 162 and 165 K at atmospheric pressure,the charge generated in the LXe TPC always needs to be read out in the cryogenic environment for minimizing the input capacitance,which has effect in determining the output noise of the charge amplifier.Purpose Design a charge readout electronics system applicable to LXe TPC and research a data analysis method to get the exact amount of charge by analyzing the waveform at that output of the designed electronics system.Methods Design a multi-channel charge-reading application specific integrated circuit(ASIC)that can operate in the cryogenic environment.The signals and power supply of the ASIC are connected to an electronics system at room temperature through micro-coaxial cables.The electronics at room temperature complete the sampling of the ASIC output.A data acquisition device receives the sampled waveform data and calculates the charge measurement resolution by Gaussian fitting.Results The designed ASIC and selected micro-coaxial cable can work in stable condition under the cryogenic environment of 165 K.The analyzed integral nonlinearity of the charge measurement of the chip is 0.83%in the range from 1 to 50 fC,and the charge measurement resolution of the chip is lower than 900 e−RMS.Conclusion In this paper,a preliminary study of the charge readout method based on the system structure of self-developed ASIC,micro-coaxial cable,and data readout electronics is completed for LXe TPC.The system test results indicate that the designed ASIC can work normally in the cryogenic temperature of 165 K with a high dynamic range and good linearity of the charge measurement.Further work can be done to reduce the charge measurement resolution of the system to 200 e−RMS.
