scholarly journals Analysis and Monitoring Technology of Upper Seam Mining in Multiunderlayer Goaf

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Han Liang ◽  
Pengfei Li ◽  
Chen Cao
Keyword(s):  
Numerical Method ◽  
Field Measurement ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Maximum Displacement ◽  
Maximum Deformation ◽  
Roof Caving ◽  
Roof Fall ◽  
Seam Mining ◽  
Roadway Deformation

Based on the background of close coal seam mining in the Qianjiaying coal mine, Tangshan, China, the feasibility of the upper seam mining in complex underlaying goaf is analysed using the roof caving analysis and numerical method. The deformation of the mining seam and roadways is monitored and analysed by field measurement and 3D laser scanning. The deformation characteristics of #5 seam after mining 1378P, 2071P, 2072P, and 2091P working panels with a depth of 39–54 m below the #5 seam are analysed using roof caving analysis and numerical method. Results show that the maximum deformation of #5 seam in the superimposed area of the lower goafs reaches 2.5 m and the maximum deformation in the single coal goaf is 1.5 m. The maximum seam inclination is 1.9°. The subsidence of the floor of 1359P roadways is obtained by field measurement, and the result is consistent with numerical calculation. ZEB-HORIZON 3D laser scanner was used to measure and model the roadway deformation. Based on the analysis of multiple scanning data, the deformation of the 1359P roadways was obtained. Results show that the deformation of the surrounding rock of the roadway is not great, the maximum displacement of the roof fall is 30 mm, and the maximum rib convergence is 25 mm. It can be concluded that the #5 seam can be recovered in this complex underlying lower seams’ mining condition.

Acquisition and Analysis on 3D Deformation of Windshield Glass in Vehicle-Pedestrian Accident

2011 ◽  
Vol 84-85 ◽  
pp. 461-465
Author(s):  
Tao Chen ◽  
Shuai Jing Wu ◽  
Jian Wei Shang ◽  
Lang Wei
Keyword(s):  
Traffic Accident ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Cloud Data ◽  
Maximum Deformation ◽  
Pedestrian Accident ◽  
3D Deformation ◽  
Continuous Curvature ◽  
New Research ◽  
The Right

A method based on the 3D laser scanning is proposed for obtaining and analyzing the windshield's deformation in vehicle-pedestrian accident. With an actual traffic accident of vehicle-pedestrian collision taken for example, point cloud data of windshield’s deformation is scanned by EXAScan 3D laser scanner and the deformed 3D NURBS surface is obtained after fitting process. Based on the discussion about characteristics of curved surface of the vehicle’s front windshield and the principle of continuous curvature, this paper conducts a surface fitting with cubic non-uniform spline according to geometric information of grid surface around the deformation zone, and obtains the pre-deformed surface of windshield by sampling with spline curve. Compared with the pre-deformed surface of vehicle’s windshield, the maximum deformation depth is 48.509mm and its area is 0.3816m2on the right side, while the maximum deformation depth is 36.341mm and its area is 0.2529m2on the left side. The application results in actual traffic accident show that this method can be used to obtain 3D deformation information of overall impact area, which provide a new method for accurately inspecting the windshield’s deformation in vehicle-pedestrian accident. This method also provides a new research idea for quantitative saving the evidence in permanent, and it also has a great value in accident analysis and reconstruction.

scholarly journals The Mechanism and Control Technology of Strong Strata Behavior in Extra-Thick Coal Seam Mining Influenced by Overlying Coal Pillar

2019 ◽  
Vol 11 (1) ◽  
pp. 452-461
Author(s):  
Rui Gao ◽  
Tiejun Kuang ◽  
Yiwen Lan
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
In Situ Monitoring ◽  
Thick Coal Seam ◽  
Maximum Deformation ◽  
Working Face ◽  
Strata Behavior ◽  
Seam Mining ◽  
Roadway Deformation ◽  
And Control

Abstract This work aimed at revealing the mechanism of strong strata behavior in extra-thick coal seam mining which was influenced by an overlying coal pillar (OCP). To this end, the evolution characteristics of the stress and displacement in advance coal body of the working face were studied via numerical simulation. On this basis, the mechanism of strong strata behavior in working face affected by OCP was revealed. In situ monitoring also demonstrated that, as the working face mining near to the position of OCP, severe rib spalling and roadway deformation frequently appeared. The scheme of strengthening the hydraulic supports resistance and adding anchor cables was put forward to control the surrounding rocks in the stope. As a result, the maximum deformation of the roadway height was 0.66m and could completely meet the demands for safe mining. The study on the mechanism of strong strata behavior in working face and the strengthen supporting scheme would provide a theoretical basis for similar mining conditions, thus ensure safe and efficiency coal seam mining.

Results of studying the dimensional accuracy of the bases of complete removable prostheses made using 3D printing and traditional technologies

2020 ◽  
pp. 34-39
Author(s):  
Vokulova Yu.A. Vokulova ◽  
E.N. Zhulev
Keyword(s):  
3D Printing ◽  
Traditional Method ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Digital Technologies ◽  
Dimensional Accuracy ◽  
3D Printer ◽  
Significance Level ◽  
Average Value ◽  
The Difference

This article presents the results of studying the dimensional accuracy of the bases of complete removable prostheses made using a 3D printer and the traditional method. Bases of complete removable prostheses were made using an intraoral laser scanner iTero Cadent (USA) and a 3D printer Asiga Max UV (Australia). To study the dimensional accuracy of the bases of complete removable prostheses, we used the DentalCAD 2.2 Valletta software. The Nonparametric Wilcoxon W-test was used for statistical analysis of the obtained data. We found that the average value of the difference with the standard for bases made using digital technologies is 0.08744±0.0484 mm. The average value of the difference with the standard for bases made by the traditional method is 0.5654±0.1611 mm. Based on these data, we concluded that the bases of complete removable prostheses made using modern digital technologies (intraoral laser scanning and 3D printer) have a higher dimensional accuracy compared to the bases of complete removable prostheses made using the traditional method with a significance level of p<0.05 (Wilcoxon's W-test=0, p=0.031). Keywords: digital technologies in dentistry, digital impressions, intraoral scanner, 3D printing, ExoCAD, complete removable dentures.

scholarly journals Estimation of Vegetation-Induced Flow Resistance for Hydraulic Computations Using Airborne Laser Scanning Data

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1864
Author(s):  
Peter Mewis
Keyword(s):  
Laser Scanning ◽  
Flow Resistance ◽  
Laser Scanner ◽  
Airborne Laser Scanning ◽  
Density Parameter ◽  
Vegetation Density ◽  
Airborne Laser Scanner ◽  
Airborne Laser ◽  
Bed Roughness ◽  
Available Information

The effect of vegetation in hydraulic computations can be significant. This effect is important for flood computations. Today, the necessary terrain information for flood computations is obtained by airborne laser scanning techniques. The quality and density of the airborne laser scanning information allows for more extensive use of these data in flow computations. In this paper, known methods are improved and combined into a new simple and objective procedure to estimate the hydraulic resistance of vegetation on the flow in the field. State-of-the-art airborne laser scanner information is explored to estimate the vegetation density. The laser scanning information provides the base for the calculation of the vegetation density parameter ωp using the Beer–Lambert law. In a second step, the vegetation density is employed in a flow model to appropriately account for vegetation resistance. The use of this vegetation parameter is superior to the common method of accounting for the vegetation resistance in the bed resistance parameter for bed roughness. The proposed procedure utilizes newly available information and is demonstrated in an example. The obtained values fit very well with the values obtained in the literature. Moreover, the obtained information is very detailed. In the results, the effect of vegetation is estimated objectively without the assignment of typical values. Moreover, a more structured flow field is computed with the flood around denser vegetation, such as groups of bushes. A further thorough study based on observed flow resistance is needed.

The Steam Turbine Retrofitting of Six Boiling Water Reactor Units Using Innovative Engineering and Laser Scanning Techniques

2009 ◽  
Author(s):  
Mike Jones ◽  
David J. Nelmes
Keyword(s):  
Steam Turbine ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Boiling Water ◽  
Boiling Water Reactors ◽  
Extensive Experience ◽  
Turbine Generators ◽  
The Usa ◽  
Water Reactors ◽  
Scan Data

Alstom Power is executing the steam turbine retrofit of six nuclear units for Exelon Generation in the USA. The existing turbine-generators are an 1800 RPM General Electric design originally rated at 912 MWe and 1098 MWe and powered by Boiling Water Reactors. 18 Low Pressure inner modules will be replaced, with the first due to be installed in March 2010. This project is particularly challenging — the aggressive retrofit installation schedule is compounded by the requirement to handle radioactively contaminated equipment and also comply with demanding regulations applicable to BWR plant. The author’s company has extensive experience in the steam turbine retrofit business, having supplied around 800 retrofit cylinders globally since the 1970’s. However, this LP upgrade challenges the established techniques used in the business and requires extraordinary effort. Traditional retrofit engineering and installation principles have been interrogated and developed to meet the specific requirements of this project. Innovative techniques are introduced, including the extensive use of the Leica HDS 6000 laser scanner to model the existing plant. The approach has advanced the field of steam turbine retrofit design and installation significantly. The first section of this paper focuses on the extraordinary considerations of the project and the challenges surrounding BWR plant. The second part describes the laser scanning technique and the application of scan data. It outlines the innovative solutions which have been developed.

Extraction of road boundary from MLS data using laser scanner ground trajectory

2021 ◽  
Vol 13 (1) ◽  
pp. 690-704
Author(s):  
Lichun Sui ◽  
Jianfeng Zhu ◽  
Mianqing Zhong ◽  
Xue Wang ◽  
Junmei Kang
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Boundary Tracking ◽  
The Road ◽  
Navigation Data ◽  
Vehicle Trajectories ◽  
Upward Slope ◽  
Tracking Model ◽  
On The Road ◽  
Boundary Model

Abstract Various means of extracting road boundary from mobile laser scanning data based on vehicle trajectories have been investigated. Independent of positioning and navigation data, this study estimated the scanner ground track from the spatial distribution of the point cloud as an indicator of road location. We defined a typical edge block consisting of multiple continuous upward fluctuating points by abrupt changes in elevation, upward slope, and road horizontal slope. Subsequently, such edge blocks were searched for on both sides of the estimated track. A pseudo-mileage spacing map was constructed to reflect the variation in spacing between the track and edge blocks over distance, within which road boundary points were detected using a simple linear tracking model. Experimental results demonstrate that the ground trajectory of the extracted scanner forms a smooth and continuous string just on the road; this can serve as the basis for defining edge block and road boundary tracking algorithms. The defined edge block has been experimentally verified as highly accurate and strongly noise resistant, while the boundary tracking algorithm is simple, fast, and independent of the road boundary model used. The correct detection rate of the road boundary in two experimental data is more than 99.2%.

scholarly journals Detecting the Competition between Moso Bamboos and Broad-Leaved Trees in Mixed Forests Using a Terrestrial Laser Scanner

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 520 ◽  
Author(s):  
Yingjie Yan ◽  
Mingpeng Xia ◽  
Shaohui Fan ◽  
Meichun Zhan ◽  
Fengying Guan
Keyword(s):  
Spatial Structure ◽  
Laser Scanning ◽  
Mixed Forest ◽  
Laser Scanner ◽  
Phyllostachys Pubescens ◽  
Mixed Forests ◽  
Individual Trees ◽  
Convex Hull Algorithm ◽  
Intensity Of Competition ◽  
Multiple Interactions

The growth of individual trees in a forest is affected by many factors, a crucial one being the intensity of competition among trees, because it affects the spatial structure of the forest and is in turn influenced by silvicultural practices. In a mixed forest in particular, the growth of trees is affected by multiple interactions. To analyse the competition between moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) and broad-leaved trees in a mixed forest, data were extracted by sampling six spots within such a forest using terrestrial laser scanning (TLS). The convex hull algorithm was used for calculating the overlap volume between the crowns of the broad-leaved trees and the bamboo canopy. Bamboos growing at least 3 m away from any of the broad-leaved trees were the most numerous and the diameter at breast height (DBH) is larger than those growing closer than that, which suggests that broad-leaved trees suppressed the growth of bamboo if they are closer but promote it beyond 3 m up to a point at which the distance is too great for any such effect. The modified Hegyi’s competition index was constructed based on the canopy factor, which may better describe the competitive interaction among the trees and bamboos. Using TLS can enhance our understanding of the competition among trees in mixed forests and help in planning the spatial structure of such forests in general and provide a benchmark for choosing planting distances in particular.

scholarly journals Segmentation and Multi-Scale Convolutional Neural Network-Based Classification of Airborne Laser Scanner Data

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3347 ◽  
Author(s):  
Zhishuang Yang ◽  
Bo Tan ◽  
Huikun Pei ◽  
Wanshou Jiang
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Region Growing ◽  
Point Clouds ◽  
Classification Method ◽  
Multi Scale ◽  
Airborne Laser

The classification of point clouds is a basic task in airborne laser scanning (ALS) point cloud processing. It is quite a challenge when facing complex observed scenes and irregular point distributions. In order to reduce the computational burden of the point-based classification method and improve the classification accuracy, we present a segmentation and multi-scale convolutional neural network-based classification method. Firstly, a three-step region-growing segmentation method was proposed to reduce both under-segmentation and over-segmentation. Then, a feature image generation method was used to transform the 3D neighborhood features of a point into a 2D image. Finally, feature images were treated as the input of a multi-scale convolutional neural network for training and testing tasks. In order to obtain performance comparisons with existing approaches, we evaluated our framework using the International Society for Photogrammetry and Remote Sensing Working Groups II/4 (ISPRS WG II/4) 3D labeling benchmark tests. The experiment result, which achieved 84.9% overall accuracy and 69.2% of average F1 scores, has a satisfactory performance over all participating approaches analyzed.

Error Modelling and Optimal Estimation of Laser Scanning Aided Inertial Navigation System in GNSS-Denied Environments

2018 ◽  
Vol 72 (3) ◽  
pp. 741-758 ◽  
Author(s):  
W.I. Liu ◽  
Zhixiong Li ◽  
Zhichao Zhang
Keyword(s):  
Kalman Filter ◽  
Navigation System ◽  
Laser Scanning ◽  
Inertial Navigation System ◽  
Laser Scanner ◽  
Inertial Navigation ◽  
Integration Algorithm ◽  
Biased Estimation ◽  
State Estimations ◽  
Estimation And Filtering

A Laser Scanning aided Inertial Navigation System (LSINS) is able to provide highly accurate position and attitude information by aggregating laser scanning and inertial measurements under the assumption that the rigid transformation between sensors is known. However, a LSINS is inevitably subject to biased estimation and filtering divergence errors due to inconsistent state estimations between the inertial measurement unit and the laser scanner. To bridge this gap, this paper presents a novel integration algorithm for LSINS to reduce the inconsistences between different sensors. In this new integration algorithm, the Radial Basis Function Neural Networks (RBFNN) and Singular Value Decomposition Unscented Kalman Filter (SVDUKF) are used together to avoid inconsistent state estimations. Optimal error estimation in the LSINS integration process is achieved to reduce the biased estimation and filtering divergence errors through the error state and measurement error model built by the proposed method. Experimental tests were conducted to evaluate the navigation performance of the proposed method in Global Navigation Satellite System (GNSS)-denied environments. The navigation results demonstrate that the relationship between the laser scanner coordinates and the inertial sensor coordinates can be established to reduce sensor measurement inconsistencies, and LSINS position accuracy can be improved by 23·6% using the proposed integration method compared with the popular Extended Kalman Filter (EKF) algorithm.

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