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
Excavation and lining are two main important tasks in tunnel construction. Conventional sequential operations may not be appropriate due to time limit for a project and the high cost of construction. The authors devel...Excavation and lining are two main important tasks in tunnel construction. Conventional sequential operations may not be appropriate due to time limit for a project and the high cost of construction. The authors developed a new mode of tunnel construction that excavation and lining can be operated simultaneously. The new mode of tunnel construction has been successfully applied to Dahuofang Water Conveyance Project in Liaoning Province. This paper makes a comparison of Main Beam TBMs and Double Shield TBMs used in Dahuofang Water Conveyance Project, and the features of Full-ring Inner-through Lining Shutter Jumbo which solves the problem of interference between excavation and lining.展开更多
We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations i...We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations in a straight edge. However, for extreme-relativistic beams, the Fresnel oscillations turn into quantum damped beats.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
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
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
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
The authors, through a descriptive retrospective study have evaluated the results of surgical treatment, by Tension-Free Obturator tape (TOT) technique, of urinary incontinence in the first 68 patients operated in the...The authors, through a descriptive retrospective study have evaluated the results of surgical treatment, by Tension-Free Obturator tape (TOT) technique, of urinary incontinence in the first 68 patients operated in the Department “C” of Obstetrics and Gynecology of the Maternity and Neonatology Centre of Tunis (WTSC). The average age in those patients was 55.14 ± 8.47 years with extremes of 40 and 82 years. The majority of the patients (72%) were under the age of 60 years. In sixty-one patients (89%), no urine leak has been detected and they were healed. In three patients (4%) there was improvement with partial recovery. Three other (4%) did not notice any improvement after the surgery. No case of dysuria or rejection of the strip has been reported. It was concluded that the declared satisfaction rate is 93%.展开更多
Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for det...Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for determining their photographic quality which correlated to the effectiveness of in-taxicab facial identification. Methods: Five photographic quality metric thresholds: 1) resolution, 2) highlight dynamic range, 3) shadow dynamic range, 4) lens distortion, and 5) shutter speed, were employed to evaluate the photographic quality of the sample cameras. Waterproof tests and fire-resistive tests on recording memory cards were conducted to determine the memory card survivability in water and simulated fire. Results: The Full-HD (1920 × 1080 pixels), HD (1280 × 720 pixels) and dual-lens VGA (2 × 640 × 480 pixels with wide-angle and telephoto lenses) cameras performed well in resolution tests in daylight conditions. The resolution of a single-lens VGA (640 × 480 pixels) camera did not meet the resolution minimum requirements. All of the recording memory cards passed the five-meter/72-hour waterproof test. A fire resistant chamber made with one fire insulation material could protect a single memory card at 538°C/1000°F for a five-minute simulated fire test. Conclusions: Single-lens VGA-resolution (640 × 480 pixels) cameras are not suggested for use as security cameras in taxicabs with two or more rows of seats. The recording memory cards can survive 5-meter/72-hour waterproof tests. The memory card chamber built with an existing heat insulation material can protect an individual memory card during 538°C?(1000°F)/5-minute fire resistance oven-test.展开更多
The densely populated foothill zone of western Himalaya between the Beas river and the Chakki stream in and around Kangra is being critically examined by us considering the seismo-tectonic destructive potential of the...The densely populated foothill zone of western Himalaya between the Beas river and the Chakki stream in and around Kangra is being critically examined by us considering the seismo-tectonic destructive potential of the 1905 (Mw 7.8) Kangra earthquake which has not been evaluated so far. We use Resourcesat 1: LISS III Ortho satellite imageries and field studies to qualitatively and quantitatively assess the active tectonic setup of the terrain. Quantitative morphotectonic analysis viz. hypsometric integral, drainage basin asymmetry, stream sinuosity index, ratio of valley floor width to valley height, stream length gradient index, basin shape index and mountain front sinuosity index are being evaluated on high resolution digital elevation model. The five sub-drainage basins of the Gandhiri stream, the Sukar stream and the Duhg stream of Kangra district of Himachal Pradesh, India are being morphotectonically analyzed. The value of hypsometric integral, drainage basin asymmetry, stream sinuosity index, ratio of valley floor width to valley height, stream length gradient index, basin shape index and mountain front sinuosity index reveal that the terrain is tectonically active. An active dextral strike slip fault with significant oblique slip component has been inferred and is being named as the Gandhiri Fault. This fault crosses all the five sub-drainage basins and results in multiple stream offsets. The Index of Relative Tectonic Activity (IRAT) has been established for different sub-drainage basins. The study reveals that the terrain near Gandhiri in Kangra district of Himachal Pradesh is seismo-tectonically active and proper building codes should be followed in construction activity.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
Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer,especially in the hot-humid climate.This study used a case study approac...Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer,especially in the hot-humid climate.This study used a case study approach to discuss the effect of low-energy strategies that can be applied to improve indoor thermal environment and cooling energy consumption of library buildings in hot and humid cities like Nanning City(a southern city,China).The use of cooling window shutters(a shutter with the effects of shading and evaporative cooling)and ceiling fans for generating airflow was considered as applicable energy-saving measures in this study,and a university library was selected as the study building in which the two energy-saving measures were employed.The SET*and annual cooling load before and after the adoption of the proposed measures were quantitatively investigated with a building energy consumption simulation software(DesignBuilder).Simulation results showed that the daytime SET*values can be reduced by 3.0℃and 4.5℃respectively on a typical summer day after the use of the cooling shutters and ceiling fans.Moreover,the cooling loads can also be decreased by 8.4%and 16.6%respectively.Particularly,the combination of these two measures enabled the daytime SET*value and annual cooling load lower by 7.0℃and 60.8%respectively.展开更多
High speed imaging technology has opened applications in many fields,such as collision,detonating,high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and...High speed imaging technology has opened applications in many fields,such as collision,detonating,high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,at the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×108―5×109 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 107―1014 fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polari-zation and wavelength,and even quantum properties of photon.In the cascaded system of electro-magnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.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
The shipbuilding industry is booming and the health problems of workers caused by the harsh indoor dock environmentforce us to explore efficient and reasonable ventilation methods suitable for large workshops.Due to t...The shipbuilding industry is booming and the health problems of workers caused by the harsh indoor dock environmentforce us to explore efficient and reasonable ventilation methods suitable for large workshops.Due to the strongspecificity of large workshops,general or local ventilation methods cannot be universally applied.It has great potentialand good economy to improve indoor environment by changing natural ventilation design.Computational fluiddynamics(CFD)has gradually become a powerful tool for predicting indoor and outdoor airflow organization andoptimizing indoor ventilation.This paper adopts CFD to study the effect of the inflow wind speed,the position of theside wall shutters,the area ratio and form of roof ventilators on the effectiveness of natural ventilation in a large shipyarddriven by wind pressure.The results show that the influence on total ventilation volume is more obvious whenthe intake side is shaded than the exhaust side.Different incoming wind speeds will affect the wind pressure at theventilation position,which is the decisive external factor affecting the natural ventilation of docks.When the area ratioof roof ventilators increases to a certain extent,its continued increase has an insignificant effect on the total ventilationvolume.The influence of changing the arrangement of the roof ventilator on the natural ventilation effect can beneglected when the area ratio is kept constant.展开更多
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.
文摘Excavation and lining are two main important tasks in tunnel construction. Conventional sequential operations may not be appropriate due to time limit for a project and the high cost of construction. The authors developed a new mode of tunnel construction that excavation and lining can be operated simultaneously. The new mode of tunnel construction has been successfully applied to Dahuofang Water Conveyance Project in Liaoning Province. This paper makes a comparison of Main Beam TBMs and Double Shield TBMs used in Dahuofang Water Conveyance Project, and the features of Full-ring Inner-through Lining Shutter Jumbo which solves the problem of interference between excavation and lining.
文摘We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations in a straight edge. However, for extreme-relativistic beams, the Fresnel oscillations turn into quantum damped beats.
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.
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.
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.
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The authors, through a descriptive retrospective study have evaluated the results of surgical treatment, by Tension-Free Obturator tape (TOT) technique, of urinary incontinence in the first 68 patients operated in the Department “C” of Obstetrics and Gynecology of the Maternity and Neonatology Centre of Tunis (WTSC). The average age in those patients was 55.14 ± 8.47 years with extremes of 40 and 82 years. The majority of the patients (72%) were under the age of 60 years. In sixty-one patients (89%), no urine leak has been detected and they were healed. In three patients (4%) there was improvement with partial recovery. Three other (4%) did not notice any improvement after the surgery. No case of dysuria or rejection of the strip has been reported. It was concluded that the declared satisfaction rate is 93%.
文摘Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for determining their photographic quality which correlated to the effectiveness of in-taxicab facial identification. Methods: Five photographic quality metric thresholds: 1) resolution, 2) highlight dynamic range, 3) shadow dynamic range, 4) lens distortion, and 5) shutter speed, were employed to evaluate the photographic quality of the sample cameras. Waterproof tests and fire-resistive tests on recording memory cards were conducted to determine the memory card survivability in water and simulated fire. Results: The Full-HD (1920 × 1080 pixels), HD (1280 × 720 pixels) and dual-lens VGA (2 × 640 × 480 pixels with wide-angle and telephoto lenses) cameras performed well in resolution tests in daylight conditions. The resolution of a single-lens VGA (640 × 480 pixels) camera did not meet the resolution minimum requirements. All of the recording memory cards passed the five-meter/72-hour waterproof test. A fire resistant chamber made with one fire insulation material could protect a single memory card at 538°C/1000°F for a five-minute simulated fire test. Conclusions: Single-lens VGA-resolution (640 × 480 pixels) cameras are not suggested for use as security cameras in taxicabs with two or more rows of seats. The recording memory cards can survive 5-meter/72-hour waterproof tests. The memory card chamber built with an existing heat insulation material can protect an individual memory card during 538°C?(1000°F)/5-minute fire resistance oven-test.
文摘The densely populated foothill zone of western Himalaya between the Beas river and the Chakki stream in and around Kangra is being critically examined by us considering the seismo-tectonic destructive potential of the 1905 (Mw 7.8) Kangra earthquake which has not been evaluated so far. We use Resourcesat 1: LISS III Ortho satellite imageries and field studies to qualitatively and quantitatively assess the active tectonic setup of the terrain. Quantitative morphotectonic analysis viz. hypsometric integral, drainage basin asymmetry, stream sinuosity index, ratio of valley floor width to valley height, stream length gradient index, basin shape index and mountain front sinuosity index are being evaluated on high resolution digital elevation model. The five sub-drainage basins of the Gandhiri stream, the Sukar stream and the Duhg stream of Kangra district of Himachal Pradesh, India are being morphotectonically analyzed. The value of hypsometric integral, drainage basin asymmetry, stream sinuosity index, ratio of valley floor width to valley height, stream length gradient index, basin shape index and mountain front sinuosity index reveal that the terrain is tectonically active. An active dextral strike slip fault with significant oblique slip component has been inferred and is being named as the Gandhiri Fault. This fault crosses all the five sub-drainage basins and results in multiple stream offsets. The Index of Relative Tectonic Activity (IRAT) has been established for different sub-drainage basins. The study reveals that the terrain near Gandhiri in Kangra district of Himachal Pradesh is seismo-tectonically active and proper building codes should be followed in construction activity.
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.
基金supported from the National Natural Science Foundation of China(No.51968003)the Guangxi Science and Technology Project(No.AB16380193).
文摘Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer,especially in the hot-humid climate.This study used a case study approach to discuss the effect of low-energy strategies that can be applied to improve indoor thermal environment and cooling energy consumption of library buildings in hot and humid cities like Nanning City(a southern city,China).The use of cooling window shutters(a shutter with the effects of shading and evaporative cooling)and ceiling fans for generating airflow was considered as applicable energy-saving measures in this study,and a university library was selected as the study building in which the two energy-saving measures were employed.The SET*and annual cooling load before and after the adoption of the proposed measures were quantitatively investigated with a building energy consumption simulation software(DesignBuilder).Simulation results showed that the daytime SET*values can be reduced by 3.0℃and 4.5℃respectively on a typical summer day after the use of the cooling shutters and ceiling fans.Moreover,the cooling loads can also be decreased by 8.4%and 16.6%respectively.Particularly,the combination of these two measures enabled the daytime SET*value and annual cooling load lower by 7.0℃and 60.8%respectively.
基金Supported by the National Natural Science Foundation of China(Grant Nos.60477042 and 60127501)
文摘High speed imaging technology has opened applications in many fields,such as collision,detonating,high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,at the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×108―5×109 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 107―1014 fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polari-zation and wavelength,and even quantum properties of photon.In the cascaded system of electro-magnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.
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supported by Shanghai 2020“Science and Technology Innovation Action Plan”for Social Development Science and Technology Research Project under the project number of 20DZ1207802.
文摘The shipbuilding industry is booming and the health problems of workers caused by the harsh indoor dock environmentforce us to explore efficient and reasonable ventilation methods suitable for large workshops.Due to the strongspecificity of large workshops,general or local ventilation methods cannot be universally applied.It has great potentialand good economy to improve indoor environment by changing natural ventilation design.Computational fluiddynamics(CFD)has gradually become a powerful tool for predicting indoor and outdoor airflow organization andoptimizing indoor ventilation.This paper adopts CFD to study the effect of the inflow wind speed,the position of theside wall shutters,the area ratio and form of roof ventilators on the effectiveness of natural ventilation in a large shipyarddriven by wind pressure.The results show that the influence on total ventilation volume is more obvious whenthe intake side is shaded than the exhaust side.Different incoming wind speeds will affect the wind pressure at theventilation position,which is the decisive external factor affecting the natural ventilation of docks.When the area ratioof roof ventilators increases to a certain extent,its continued increase has an insignificant effect on the total ventilationvolume.The influence of changing the arrangement of the roof ventilator on the natural ventilation effect can beneglected when the area ratio is kept constant.
