Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limi...Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limited to the quantity of air moving through any given heading. Because computer-aided modelling, simulation, and ventilation system design tools have improved, it is now important to ensure that developed models have the most accurate information possible. This paper presents a new technique for estimating underground drift friction factors that works by processing 3 D point cloud data obtained by using a mobile Li DAR. Presented are field results that compare the proposed approach with previously published algorithms, as well as with manually acquired measurements.展开更多
CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated ...CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated utility in capturing forest structure information. This paper proposes an indirect method of assessing downed CWD using LiDAR derived forest structure variables. Fieldwork was conducted to measure CWD volume in an Eucalyptus forest in Tasmania. A GLM (generalized linear model) to statistically estimate CWD volume in the Eucalyptus forest was developed using a LiDAR derived FCS (forest characterisation scheme): the openings above the ground, low and medium vegetation, canopy cover, presence of understorey and mid-storey vegetation and high trees, and the vertical canopy density of high trees. Five structural variables were selected for the best model based on AIC (Akaike's Information Criterion) by stepwise selection. The applicability of the model was then compared to the outcome of model using field derived variables such as diameter at breast height of trees. The results show that the model using LiDAR derived variables better estimated the amount of CWD. It is concluded that LiDAR derived forest structural variables has the potential to predict the amount of downed CWD in Eucalyptus forest.展开更多
New LIDAR (Light Detection and Ranging) and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly v...New LIDAR (Light Detection and Ranging) and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly visible on LIDAR and sonar images. Many previously unknown faults criss-cross the islands and large fault scarps are visible on sonar imagery along the margins of the larger islands. Sonar images of sea floor morphology show many submerged faults as long linear scarps with relief up to 300m (1,000 fl), some of which visibly truncate geologic structures. The San Juan Lopez fault, the largest fault in the islands, extends for at least 65 km (40 mi) from Stuart Island to Rosario strait with a scarp up to 330m (1,000 it) high. Since 1975, the basic structural framework of the San Juan Islands has been considered to consist of five stacked thrust faults, the Rosario, Orcas, Haro, Lopez, and Buck Bay faults, constituting the San Juan Thrust (Nappe) System that has shuffled together far distant terranes. However, the new LIDAR and sonar imagery shows that most of the mapped extent of these postulated faults are actually segments of high angle, dipslip faults and are not thrust faults at all. Thus, the San Juan Thrust (Nappe) System does not exist. The age of these faults is not accurately known and more than one period of high angle faulting may have occurred. Faults shown on L1DAR images of the surface of the islands appear as visible gashes, etched out by erosion of fault zones with few fault scarps. However, the sea floor faults have bold relief and high scarps. A late Pleistocene moraine lies undisturbed across the San Juan Lopez fault.展开更多
This paper describes a full waveform sampling LiDAR system applying stripe principle. A kind of denoising method based on edge detection of original stripe signal is proposed. This method is compared with other denois...This paper describes a full waveform sampling LiDAR system applying stripe principle. A kind of denoising method based on edge detection of original stripe signal is proposed. This method is compared with other denoising methods, such as Wiener filtering, mean filtering and median filtering. It is found that the proposed denoising method is much more effective for dealing with the waveform signals.展开更多
During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The res...During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum(FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content(TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results.展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) under grant CRDPJ 44580412Barrick Gold Corporation and Peck Tech Consulting Ltd
文摘Ventilation system analysis for underground mines has remained mostly unchanged since the Atkinson method was made popular by Mc Elroy in 1935. Data available to ventilation technicians and engineers is typically limited to the quantity of air moving through any given heading. Because computer-aided modelling, simulation, and ventilation system design tools have improved, it is now important to ensure that developed models have the most accurate information possible. This paper presents a new technique for estimating underground drift friction factors that works by processing 3 D point cloud data obtained by using a mobile Li DAR. Presented are field results that compare the proposed approach with previously published algorithms, as well as with manually acquired measurements.
文摘CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated utility in capturing forest structure information. This paper proposes an indirect method of assessing downed CWD using LiDAR derived forest structure variables. Fieldwork was conducted to measure CWD volume in an Eucalyptus forest in Tasmania. A GLM (generalized linear model) to statistically estimate CWD volume in the Eucalyptus forest was developed using a LiDAR derived FCS (forest characterisation scheme): the openings above the ground, low and medium vegetation, canopy cover, presence of understorey and mid-storey vegetation and high trees, and the vertical canopy density of high trees. Five structural variables were selected for the best model based on AIC (Akaike's Information Criterion) by stepwise selection. The applicability of the model was then compared to the outcome of model using field derived variables such as diameter at breast height of trees. The results show that the model using LiDAR derived variables better estimated the amount of CWD. It is concluded that LiDAR derived forest structural variables has the potential to predict the amount of downed CWD in Eucalyptus forest.
文摘New LIDAR (Light Detection and Ranging) and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly visible on LIDAR and sonar images. Many previously unknown faults criss-cross the islands and large fault scarps are visible on sonar imagery along the margins of the larger islands. Sonar images of sea floor morphology show many submerged faults as long linear scarps with relief up to 300m (1,000 fl), some of which visibly truncate geologic structures. The San Juan Lopez fault, the largest fault in the islands, extends for at least 65 km (40 mi) from Stuart Island to Rosario strait with a scarp up to 330m (1,000 it) high. Since 1975, the basic structural framework of the San Juan Islands has been considered to consist of five stacked thrust faults, the Rosario, Orcas, Haro, Lopez, and Buck Bay faults, constituting the San Juan Thrust (Nappe) System that has shuffled together far distant terranes. However, the new LIDAR and sonar imagery shows that most of the mapped extent of these postulated faults are actually segments of high angle, dipslip faults and are not thrust faults at all. Thus, the San Juan Thrust (Nappe) System does not exist. The age of these faults is not accurately known and more than one period of high angle faulting may have occurred. Faults shown on L1DAR images of the surface of the islands appear as visible gashes, etched out by erosion of fault zones with few fault scarps. However, the sea floor faults have bold relief and high scarps. A late Pleistocene moraine lies undisturbed across the San Juan Lopez fault.
基金supported by the National Natural Science Foundation of China(No.11004042)the National Key Scientific Instrument and Equipment Development Projects(No.2012YQ040164)the Science Funds of Heilongjiang Province(No.F2016015)
文摘This paper describes a full waveform sampling LiDAR system applying stripe principle. A kind of denoising method based on edge detection of original stripe signal is proposed. This method is compared with other denoising methods, such as Wiener filtering, mean filtering and median filtering. It is found that the proposed denoising method is much more effective for dealing with the waveform signals.
基金supported by the National Natural Science Foundation of China(Grant Nos.1097800341104101+1 种基金41101334)the National High-tech R&D Program
文摘During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum(FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content(TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results.