The star identification algorithm usually identifies stars by angular distance matching.However,under high dynamic conditions,the rolling shutter effect distorts the angular distances between the measured and true sta...The star identification algorithm usually identifies stars by angular distance matching.However,under high dynamic conditions,the rolling shutter effect distorts the angular distances between the measured and true star positions,leading to plethoric false matches and requiring complex and time-consuming verification for star identification.Low identification rate hinders the application of low-noise and cost-effective rolling shutter image sensors.In this work,we first study a rolling shutter distortion model of angular distances between stars,and then propose a novel three-stage star identification algorithm to identify distorted star images captured by the rolling shutter star sensor.The first stage uses a modified grid algorithm with adaptive error tolerance and an expanded pattern database to efficiently eliminate spurious matches.The second stage performs angular velocity estimation based on Hough transform to verify the matches that follow the same distortion pattern.The third stage applies a rolling shutter error correction method for further verification.Both the simulation and night sky image test demonstrate the effectiveness and efficiency of our algorithm under high dynamic conditions.The accuracy of angular velocity estimation method by Hough transform is evaluated and the root mean square error is below 0.5(°)/s.Our algorithm achieves a 95.7% identification rate at an angular velocity of 10(°)/s,which is much higher than traditional algorithms.展开更多
Although optical camera communication(OCC) is gaining increasing attention in research, developing a practical OCC system to increase data rate and transmission distance is still an issue. The rolling shutter can incr...Although optical camera communication(OCC) is gaining increasing attention in research, developing a practical OCC system to increase data rate and transmission distance is still an issue. The rolling shutter can increase data rate, but it also limits the transmission distance at the same time. When the transmission distance is long, the thresholding method will become difficult and the block sequence number(BSN) is easy to be wrong due to bit errors, which will make it impossible to reorder the frame sequences. In this paper, in order to increase the transmission distance, we propose the efficient thresholding method which transforms partial mean gray values of per column nonlinearly to increase the contrast between light and dark bands. In addition, this method takes the frame image of the camera as the basic unit to adjust the threshold for the environment in which each frame of the image is located. Experimental results show that this method is better than the polynomial regression. Moreover, we perform the error correction of BSN by using its continuity to specify the legal BSNs and the illegal BSNs.展开更多
Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high curr...Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90 kA to140 kA and discharging current periods of approximately 13.1μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.展开更多
Due to the electronic rolling shutter, high-speed Complementary Metal-Oxide Semiconductor( CMOS) aerial cameras are generally subject to geometric distortions,which cannot be perfectly corrected by conventional vision...Due to the electronic rolling shutter, high-speed Complementary Metal-Oxide Semiconductor( CMOS) aerial cameras are generally subject to geometric distortions,which cannot be perfectly corrected by conventional vision-based algorithms. In this paper we propose a novel approach to address the problem of rolling shutter distortion in aerial imaging. A mathematical model is established by the coordinate transformation method. It can directly calculate the pixel distortion when an aerial camera is imaging at arbitrary gesture angles.Then all pixel distortions form a distortion map over the whole CMOS array and the map is exploited in the image rectification process incorporating reverse projection. The error analysis indicates that within the margin of measuring errors,the final calculation error of our model is less than 1/2 pixel. The experimental results show that our approach yields good rectification performance in a series of images with different distortions. We demonstrate that our method outperforms other vision-based algorithms in terms of the computational complexity,which makes it more suitable for aerial real-time imaging.展开更多
A major obstacle to the broad application of cathodic arc plasma deposition is the presence of macroparticles. In this paper, the properties of the large rectangular arc ion plating with a magnetic filtering shutter s...A major obstacle to the broad application of cathodic arc plasma deposition is the presence of macroparticles. In this paper, the properties of the large rectangular arc ion plating with a magnetic filtering shutter system to filter macroparticles are studied. It is proposed that the macroparticles in the plasma beam are effectively removed with the magnetic filtering shutter system, and the quality of the deposited films is improved.展开更多
This paper introduces a set of electrical energy-saving system for commercial office buildings,aiming at making better use of solar energy and photovoltaic power generation.Solar energy is a renewable energy source,wh...This paper introduces a set of electrical energy-saving system for commercial office buildings,aiming at making better use of solar energy and photovoltaic power generation.Solar energy is a renewable energy source,which is inexhaustible clean energy and has great commercial application value.Based on this fact,we plan to design a unique and novel solar shutter in combination with the daily observation and the shape of solar panels.The shutter blades are equipped with an automatic light tracking system,and the angle of the blades can be adjusted in time through photoresistor induction,that is,as much solar energy as possible can be converted into electric energy for load use,and at the same time,comfortable light can be provided for the house.In essence,the system is a small photovoltaic power generation system,which runs all day with high-efficiency based on automatic sun tracking.Among them,the basic operation route includes:solar position detection,computer data processing,photovoltaic and electric volt energy conversion,circuit connection,etc.From the current debugging results,the shutter has the characteristics of humanization,high efficiency,cleanliness and so on.Through this energy-saving system,we hope to maximize the use of solar energy in the premise of low cost,so as to achieve the purpose of energy saving.展开更多
High power lasers (> +21dBm) have gradually become the common solution for signal transmitting systems including regional cable television, Fiber To The Home (FTTH), and gigabit passive optical networks (G- PONs) d...High power lasers (> +21dBm) have gradually become the common solution for signal transmitting systems including regional cable television, Fiber To The Home (FTTH), and gigabit passive optical networks (G- PONs) due to their ability to generate signals that can be transmitted over long distances. However, if protective design is not implemented in the facility at the client side, users may be exposed to health hazards such as eye damage from these high-power lasers. High-power optical adapters with laser shutter use metal masks to prevent eye exposure to direct laser beams. They have progressively replaced conventional optical adapters and entered the market mainstream. Our study uses the Elastic-Plastic theory together with parametric design to investigate the effect of geometry on the initial spring-back angle of a laser shutter. Once the force stabilizes, the angles of the initial spring back are found to be the same as the simulated results for several attempts. In our study, it is observed that factors including the thickness of the metal masking plate, the initial design angle, the stiffness of the material and the boundary conditions have significant influence on the spring back angle. These can be used as references in design control.展开更多
BEiJlNG housewife Liu Lifei described how she and her family started to feel claustrophobic in their apartment. Sharing 90 square meters of space with her husband, in-laws and son. it became increasingly crowded espec...BEiJlNG housewife Liu Lifei described how she and her family started to feel claustrophobic in their apartment. Sharing 90 square meters of space with her husband, in-laws and son. it became increasingly crowded especially with son Yangyang growing up. But the ultra-high housing prices in Beijing made the family＇s dream of moving into a bigger apartment simply unattainable.展开更多
The safety shutter of the SR (synchrotron radiation) facility located at the front end of the facility is an in- dispensable component for radiation protection. Its thickness is decided by the gas bremsstrahlung produ...The safety shutter of the SR (synchrotron radiation) facility located at the front end of the facility is an in- dispensable component for radiation protection. Its thickness is decided by the gas bremsstrahlung produced in the SR facility storage ring by the interaction of electrons with the residual gas molecules in the vacuum chamber of the storage ring. In the calculation, the 3.5 GeV, 300 mA electron beam and a 15 m long insertion-device straight section (0.133 μ Pa) were taken into account, and the safety shutter was assumed to be located 12 m away from the end of the straight section. The EGSnrc code based on the Monte-Carlo method and empirical formulas were used, respectively, to calculate the thickness to satisfy the shielding requirement of the safety shutter at the front end of the SR facility, and the results were compared and the availability of EGSnrc was proved.展开更多
In the past few decades, Hydrogen sulfide （H2S） has been newly witnessed as a third gasotransmitter with similar biological functions to its two previously identified counterparts nitric oxide （NO） and carbon mono...In the past few decades, Hydrogen sulfide （H2S） has been newly witnessed as a third gasotransmitter with similar biological functions to its two previously identified counterparts nitric oxide （NO） and carbon monoxide （CO）, after being recognized as a toxic gas with an unpleasant rotten-egg smell for hundreds of years. Following the recognition of its great pharmacological potential in mammalian （Mani et al., 2015）,展开更多
Most modern consumer-grade cameras are often equipped with a rolling shutter mechanism,which is becoming increasingly important in computer vision,robotics and autonomous driving applications.However,its temporal-dyna...Most modern consumer-grade cameras are often equipped with a rolling shutter mechanism,which is becoming increasingly important in computer vision,robotics and autonomous driving applications.However,its temporal-dynamic imaging nature leads to the rolling shutter effect that manifests as geometric distortion.Over the years,researchers have made significant progress in developing tractable rolling shutter models,optimization methods,and learning approaches,aiming to remove geometry distortion and improve visual quality.In this survey,we review the recent advances in rolling shutter cameras from two aspects of motion modeling and deep learning.To the best of our knowledge,this is the first comprehensive survey of rolling shutter cameras.In the part of rolling shutter motion modeling and optimization,the principles of various rolling shutter motion models are elaborated and their typical applications are summarized.Then,the applications of deep learning in rolling shutter based image processing are presented.Finally,we conclude this survey with discussions on future research directions.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFA0706002).
文摘The star identification algorithm usually identifies stars by angular distance matching.However,under high dynamic conditions,the rolling shutter effect distorts the angular distances between the measured and true star positions,leading to plethoric false matches and requiring complex and time-consuming verification for star identification.Low identification rate hinders the application of low-noise and cost-effective rolling shutter image sensors.In this work,we first study a rolling shutter distortion model of angular distances between stars,and then propose a novel three-stage star identification algorithm to identify distorted star images captured by the rolling shutter star sensor.The first stage uses a modified grid algorithm with adaptive error tolerance and an expanded pattern database to efficiently eliminate spurious matches.The second stage performs angular velocity estimation based on Hough transform to verify the matches that follow the same distortion pattern.The third stage applies a rolling shutter error correction method for further verification.Both the simulation and night sky image test demonstrate the effectiveness and efficiency of our algorithm under high dynamic conditions.The accuracy of angular velocity estimation method by Hough transform is evaluated and the root mean square error is below 0.5(°)/s.Our algorithm achieves a 95.7% identification rate at an angular velocity of 10(°)/s,which is much higher than traditional algorithms.
基金supported by the Department of Science and Technology of Jilin Province(No.20180101040JC)
文摘Although optical camera communication(OCC) is gaining increasing attention in research, developing a practical OCC system to increase data rate and transmission distance is still an issue. The rolling shutter can increase data rate, but it also limits the transmission distance at the same time. When the transmission distance is long, the thresholding method will become difficult and the block sequence number(BSN) is easy to be wrong due to bit errors, which will make it impossible to reorder the frame sequences. In this paper, in order to increase the transmission distance, we propose the efficient thresholding method which transforms partial mean gray values of per column nonlinearly to increase the contrast between light and dark bands. In addition, this method takes the frame image of the camera as the basic unit to adjust the threshold for the environment in which each frame of the image is located. Experimental results show that this method is better than the polynomial regression. Moreover, we perform the error correction of BSN by using its continuity to specify the legal BSNs and the illegal BSNs.
基金This project supported by the National Nature Science Foundation of China (No. 10035020 )
文摘Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90 kA to140 kA and discharging current periods of approximately 13.1μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.
基金Sponsored by the National Natural Science Foundation of China(Grant No.60902067)the Foundation for Science & Technology Research Project of Jilin Province(Grant No.11ZDGG001)
文摘Due to the electronic rolling shutter, high-speed Complementary Metal-Oxide Semiconductor( CMOS) aerial cameras are generally subject to geometric distortions,which cannot be perfectly corrected by conventional vision-based algorithms. In this paper we propose a novel approach to address the problem of rolling shutter distortion in aerial imaging. A mathematical model is established by the coordinate transformation method. It can directly calculate the pixel distortion when an aerial camera is imaging at arbitrary gesture angles.Then all pixel distortions form a distortion map over the whole CMOS array and the map is exploited in the image rectification process incorporating reverse projection. The error analysis indicates that within the margin of measuring errors,the final calculation error of our model is less than 1/2 pixel. The experimental results show that our approach yields good rectification performance in a series of images with different distortions. We demonstrate that our method outperforms other vision-based algorithms in terms of the computational complexity,which makes it more suitable for aerial real-time imaging.
文摘A major obstacle to the broad application of cathodic arc plasma deposition is the presence of macroparticles. In this paper, the properties of the large rectangular arc ion plating with a magnetic filtering shutter system to filter macroparticles are studied. It is proposed that the macroparticles in the plasma beam are effectively removed with the magnetic filtering shutter system, and the quality of the deposited films is improved.
文摘This paper introduces a set of electrical energy-saving system for commercial office buildings,aiming at making better use of solar energy and photovoltaic power generation.Solar energy is a renewable energy source,which is inexhaustible clean energy and has great commercial application value.Based on this fact,we plan to design a unique and novel solar shutter in combination with the daily observation and the shape of solar panels.The shutter blades are equipped with an automatic light tracking system,and the angle of the blades can be adjusted in time through photoresistor induction,that is,as much solar energy as possible can be converted into electric energy for load use,and at the same time,comfortable light can be provided for the house.In essence,the system is a small photovoltaic power generation system,which runs all day with high-efficiency based on automatic sun tracking.Among them,the basic operation route includes:solar position detection,computer data processing,photovoltaic and electric volt energy conversion,circuit connection,etc.From the current debugging results,the shutter has the characteristics of humanization,high efficiency,cleanliness and so on.Through this energy-saving system,we hope to maximize the use of solar energy in the premise of low cost,so as to achieve the purpose of energy saving.
文摘High power lasers (> +21dBm) have gradually become the common solution for signal transmitting systems including regional cable television, Fiber To The Home (FTTH), and gigabit passive optical networks (G- PONs) due to their ability to generate signals that can be transmitted over long distances. However, if protective design is not implemented in the facility at the client side, users may be exposed to health hazards such as eye damage from these high-power lasers. High-power optical adapters with laser shutter use metal masks to prevent eye exposure to direct laser beams. They have progressively replaced conventional optical adapters and entered the market mainstream. Our study uses the Elastic-Plastic theory together with parametric design to investigate the effect of geometry on the initial spring-back angle of a laser shutter. Once the force stabilizes, the angles of the initial spring back are found to be the same as the simulated results for several attempts. In our study, it is observed that factors including the thickness of the metal masking plate, the initial design angle, the stiffness of the material and the boundary conditions have significant influence on the spring back angle. These can be used as references in design control.
文摘BEiJlNG housewife Liu Lifei described how she and her family started to feel claustrophobic in their apartment. Sharing 90 square meters of space with her husband, in-laws and son. it became increasingly crowded especially with son Yangyang growing up. But the ultra-high housing prices in Beijing made the family＇s dream of moving into a bigger apartment simply unattainable.
文摘The safety shutter of the SR (synchrotron radiation) facility located at the front end of the facility is an in- dispensable component for radiation protection. Its thickness is decided by the gas bremsstrahlung produced in the SR facility storage ring by the interaction of electrons with the residual gas molecules in the vacuum chamber of the storage ring. In the calculation, the 3.5 GeV, 300 mA electron beam and a 15 m long insertion-device straight section (0.133 μ Pa) were taken into account, and the safety shutter was assumed to be located 12 m away from the end of the straight section. The EGSnrc code based on the Monte-Carlo method and empirical formulas were used, respectively, to calculate the thickness to satisfy the shielding requirement of the safety shutter at the front end of the SR facility, and the results were compared and the availability of EGSnrc was proved.
基金supported by the National Natural Science Foundation of China(31372085 to Yanxi Pei,31400237 to Zhuping Jin)
文摘In the past few decades, Hydrogen sulfide （H2S） has been newly witnessed as a third gasotransmitter with similar biological functions to its two previously identified counterparts nitric oxide （NO） and carbon monoxide （CO）, after being recognized as a toxic gas with an unpleasant rotten-egg smell for hundreds of years. Following the recognition of its great pharmacological potential in mammalian （Mani et al., 2015）,
基金This work was supported in part by National Natural Science Foundation of China(Nos.62271410,61901387 and 62001394)the Fundamental Research Funds for the Central Universities,China,and the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2022046).
文摘Most modern consumer-grade cameras are often equipped with a rolling shutter mechanism,which is becoming increasingly important in computer vision,robotics and autonomous driving applications.However,its temporal-dynamic imaging nature leads to the rolling shutter effect that manifests as geometric distortion.Over the years,researchers have made significant progress in developing tractable rolling shutter models,optimization methods,and learning approaches,aiming to remove geometry distortion and improve visual quality.In this survey,we review the recent advances in rolling shutter cameras from two aspects of motion modeling and deep learning.To the best of our knowledge,this is the first comprehensive survey of rolling shutter cameras.In the part of rolling shutter motion modeling and optimization,the principles of various rolling shutter motion models are elaborated and their typical applications are summarized.Then,the applications of deep learning in rolling shutter based image processing are presented.Finally,we conclude this survey with discussions on future research directions.
