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A practical application of photogrammetry to performing rib characterization measurements in an underground coal mine using a DSLR camera

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International Journal of Mining Science and Technology 2017年第1期27卷 83-90页

作者： brent A.slaker Khaled M.Mohamed Mining Engineer Ground Control Branch NIOSH Office of Mine Safety and Health ResearchPittsburghPAUSA

Understanding coal mine rib behavior is important for inferring pillar loading conditions as well as ensuring the safety of miners who are regularly exposed to ribs. Due to the variability in the geometry of underground openings and ground behavior, point measurements often fail to capture the true movement of mine workings. Photogrammetry is a potentially fast, cheap, and precise supplemental measurement tool in comparison to extensometers, tape measures, or laser range meters, but its application in underground coal has been limited. The practical use of photogrammetry was tested at the Safety Research Coal Mine, National Institute for Occupational Safety and Health(NIOSH). A commercially available, digital single-lens reflex(DSLR) camera was used to perform the photogrammetric surveys for the experiment. Several experiments were performed using different lighting conditions, distances to subject,camera settings, and photograph overlaps, with results summarized as follows: the lighting method was found to be insignificant if the scene was appropriately illuminated. It was found that the distance to the subject has a minimal impact on result accuracy, and that camera settings have a significant impact on the photogrammetric quality of images. An increasing photograph resolution was preferable when measuring plane orientations; otherwise a high point cloud density would likely be excessive. Focal ratio(F-stop) changes affect the depth of field and image quality in situations where multiple angles are necessary to survey cleat orientations. Photograph overlap is very important to proper three-dimensional reconstruction, and at least 60% overlap between photograph pairs is ideal to avoid unnecessary post-processing. The suggestions and guidelines proposed are designed to increase the quality of photogrammetry inputs and outputs as well as minimize processing time, and serve as a starting point for an underground coal photogrammetry study.

关键词： Photogrammetry Coal mining Underground Rib characterization

Evaluation of stress-control layout at the Subtropolis Mine,Petersburg,Ohio

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International Journal of Mining Science and Technology 2020年第1期30卷 77-83页

作者： Anthony Iannacchione Tim Miller Gabriel Esterhuizen brent slaker Michael Murphy Natalie Cope Scott Thayer Department of Civil and Environmental Engineering University of PittsburghPittsburghPA 15216USA East Fairfield Coal Company North LimaOH 44452USA National Institute for Occupational Safety and Health(NIOSH) Pittsburgh Mining Research DivisionPittsburghPA 15236USA Mine Vision Systems Inc. PittsburghPA 1520USA

The Subtropolis room-and-pillar mine extracts the Vanport Limestone(Allegheny Formation,Pennsylvanian System)near Petersburg,*** instability problems associated with excessive concentrations of lateral stress caused the mine operator to implement a change in layout *** mining method has been identified as a stress control layout and has been used by other underground stone mines in the past with varying degrees of *** experience has shown that entry headings advance in the direction of the principal lateral stress,producing lower stress concentrations with better mining *** is important to minimize stress concentrations along the mining front,so an arrowshaped advance is *** technique advances more developments(headings)in a"good"direction and reduces developments(crosscuts)in the"bad direction."As is expected,the stress control layout enhances the potential for shear failures in *** is,therefore,important to focus crosscut engineering interventions that either:(a)lower stress concentrations(for example,an arched roof)or(b)enhance strength of the strata containing the shears(for example,rock reinforcement).This study focuses on observing strata conditions on a regular basis and monitoring the response of these strata to changing geologic and mining conditions through 3D Dynamic LiDAR scans.

关键词： Horizontal stress Stress-control layouts Underground stone mines

Determination of volumetric changes at an underground stone mine： a photogrammetry case study

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International Journal of Mining Science and Technology 2016年第1期26卷 149-154页

作者： slaker brent Westman Erik Ellenberger John Murphy Michael Virginia Polytechnic Institute and State University Blacksburg 24060 USA Office of Mine Safety and Health Research NIOSH Pittsburgh PA 15236 USA

Photogrammetry, as a tool for monitoring underground mine deformation, is an alternative to traditional point measurement devices, and may be capable of accurate measurements in situations where technolo- gies such as laser scanning are unsuited, undesired, or cost-prohibitive. An underground limestone mine in Ohio is used as a test case for monitoring of structurally unstable pillars. Seven pillars were pho- tographed over in a 63 day period, punctuated by four visits. Using photogrammetry, point clouds of the mine geometry were obtained and triangulation surfaces were generated to determine volumes of change over time. Pillar spaUing in the range of 0.29-4.03 m3 of rock on individual rib faces was detected. Isolated incidents of rock expansion prior to failure, and the isolated failure of a weak shale band were also observed. Much of the pillars remained unchanged during the monitoring period, which is indicative of proper alignment in the triangulated surfaces. The photographs of some ribs were of either too poor quality or had insufficient overlap, and were not included. However, photogrammetry was successfully aonlied to multiole ribs in auantifving the oillar geometrv change over time.

关键词： PhotogrammetryLimestoneUnderground miningDisplacementMonitoring

Global patterns and ecological drivers of taxonomic and phylogenetic endemism in angiosperm genera

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Plant Diversity 2024年第2期46卷 149-157页

作者： Hong Qian brent D.Mishler Jian Zhang Shenhua Qian Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA University and Jepson Herbaria Department of Integrative BiologyUniversity of CaliforniaBerkeleyCA 94720-2465USA Center for Global Change and Complex Ecosystems Zhejiang Tiantong Forest Ecosystem National Observation and Research StationSchool of Ecological and Environmental SciencesEast China Normal UniversityShanghai 200241China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of EducationChongqing UniversityChongqing 400045China

Endemism of lineages lies at the core of understanding variation in community composition among geographic regions because it reflects how speciation,extinction,and dispersal have influenced current ***,we investigated geographic patterns and ecological drivers of taxonomic and phylogenetic endemism of angiosperm genera across the *** identify centers of paleo-endemism and neo-endemism of angiosperm genera,and show that they are mostly located in the Southern Hemisphere in tropical and subtropical regions,particularly in Asia and *** categories of phylogenetic endemism centers can be differentiated using current climate *** climate,historical climate change,and geographic variables together explained~80%of global variation in taxonomic and phylogenetic endemism,while 42-46%,1%,and 15%were independently explained by these three types of variables,*** our findings show that past climate change,current climate,and geography act together in shaping endemism,which are consistent with the findings of previous studies that higher temperature and topographic heterogeneity promote *** study showed that many centers of phylogenetic endemism of angiosperms,including regions in Amazonia,Venezuela,and west-central tropical Africa that have not previously been identified as biodiversity hotspots,are missed by taxon-based measures of endemism,indicating the importance of including evolutionary history in biodiversity assessment.

关键词： Angiosperm Current climate Endemism Historical climate change Topographic heterogeneity

Experimental and analytical investigation on friction resistance force between buried coated pressurized steel pipes and soil

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 615-629页

作者： Shaurav ALAM Tanvir MANZUR John MATTHEWS Chris BARTLETT Erez ALLOUCHE brent KEIL John KRAFT Department of Civil Engineering and Construction Engineering Technology Louisiana Tech UniversityRustonLA 71270USA Department of Civil Engineering Bangladesh University of Engineering and TechnologyDhaka 1000Bangladesh Georgia Tech Research Institute AtlantaGA 30332USA Stantec Inc. Edmonton T5J0K4Canada North West Pipe Company VancouverWA 98684USA

This paper presents an analytical approach for estimating frictional resistance to pipe movement at soil and external pipe surface of buried coated pressurized steel pipes relative to the internal thrust *** proposed analytical method was developed based on 36 experiments,which involved three coating types(cement mortar(CM),polyurethane type-I(PT-I),prefabricated plastic tape(PPT))on pipes’surfaces,three different soils(pea-gravel(PG),sand(S),silty-clay(SC)),and four simulated over burden depths above the pipe’s *** showed frictional resistance decreased with increasing over burden depth above the pipe’s *** degree of frictional resistance at the pipe-soil interface was found to be in the order of PG>SC>S for all coating variations and overburden *** coated pipe buried in all three types of soil produced significantly higher frictional resistance as compared to other coating *** on experimental data,the developed analytical introduced a dimensionless factor“Z”,which included effects of types of coatings,soil,and overburden depths for simplified rapid *** showed that the method provided a better prediction of frictional resistance forces,in comparison to previous analytical methods,which were barely close in predicting friction resistance for different coating variations,soil types,and overburden *** resistance force values reported herein could be considered conservative.

关键词： friction resistance force thrust force coated pressurized steel pipe soil type overburden depth

Orientation Bias of Self-Assembled Alkanes and Their Derivatives Under Dynamic Lateral Nanoconfinement Conditions

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CCS Chemistry 2024年第4期6卷 1024-1033页

作者： Conditions Lihua Yu Yuanzhi Xia Tianze Hu brent Daelemans Steven De Feyter Department of Chemistry Division of Molecular Imaging and PhotonicsKU LeuvenB-3001 Leuven

Self-assembled molecular networks(SAMNs)formed on crystalline solid substrates result from the spontaneous arrangement of individual molecules into structured *** interaction between molecules and the substrate leads to a nonrandom orientation of SAMNs with respect to the substrate’s *** the case of graphite,the sixfold rotational symmetry of the substrate results in an equivalent rotational degeneracy in the orientation of *** this study,we explored how nanoconfinement,that is,the restriction of SAMN formation to nanometersized areas,known as nanocorrals,could impact and potentially alleviate the orientational degeneracy of SAMNs,with emphasis on the influence of molecule symmetry,size,and intermolecular *** this end,we investigated the orientation distribution of n-alkanes and functionalized alkanes within nanocorrals,which were fabricated using scanning tunneling microscopy lithography(nanoshaving).We observed lifting of orientational degeneracy for long alkanes,contrary to shorter alkanes,which did not exhibit this orientation ***,functionalized alkanes with hydrogen bonding groups demonstrated preferential alignment regardless of length,highlighting the significance of stabilizing intermolecular interactions in the alignment *** study discussed the underlying principles of the molecular packing process and shed light on the complexity of molecular self-assembly in nanoconfined spaces.

关键词： self-assembly confinement condition nanocorral orientation bias scanning tunneling microscopy

Scalable parallel ultrafast optical random bit generation based on a single chaotic microcomb

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Light(Science & Applications) 2024年第4期13卷 637-644页

作者： Pu Li Qizhi Li Wenye Tang Weiqiang Wang Wenfu Zhang brent ELittle Sai Tek Chu KAlan Shore Yuwen Qin Yuncai Wang Institute of Advanced Photonics Technology School of Information EngineeringGuangdong University of TechnologyGuangzhou 51006China. Key Laboratory of Photonic Technology for Integrated Sensing and Communication Ministry of Education of ChinaGuangdong University of TechnologyGuangzhou 51006China. Guangdong Provincial Key Laboratory of Information Photonics Technology Guangdong University of TechnologyGuangzhou 51006China. Key Laboratory of Advanced Transducers andIntelligent Control System Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China. State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi’an 710119China. Department of Physics and Materials Science City University of Hong KongHong KongChina. School of Electronic Engineering Bangor UniversityBangorWales LL571UTUK

Random bit generators are critical for information security,cryptography,stochastic modeling,and *** and scalability are key challenges faced by current physical random bit ***,we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator.A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams.A proof-of-concept experiment demonstrates that using our method,random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb *** bit rate can be easily enhanced by further increasing the number of comb lines *** approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation,and offers superhigh speed and large scalability.

关键词： resonator random chaotic

Simultaneous genetic transformation and genome editing of mixed lines in soybean(Glycine max)and maize(Zea mays)

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aBIOTECH 2024年第2期5卷 169-183页

作者： Michelle Valentine David Butruille Frederic Achard Steven Beach brent Brower-Toland Edward Cargill Megan Hassebrock Jennifer Rinehart Thomas Ream Yurong Chen Bayer Crop Science 700 Chesterfield Parkway WChesterfieldMO 63017USA

Robust genome editing technologies are becoming part of the crop breeding ***,genome editing is usually conducted either at a single locus,or multiple loci,in a variety at one *** parallel genomics platforms,multifaceted genome editing capabilities,and flexible transformation systems enable targeted variation at nearly any locus,across the spectrum of genotypes within a *** demonstrate here the simultaneous transformation and editing of many genotypes,by targeting mixed seed embryo explants with genome editing machinery,followed by re-identification through genotyping after plant *** and Editing of Mixed Lines(TREDMIL)produced transformed individuals representing 101 of 104(97%)mixed elite genotypes in soybean;and 22 of 40(55%)and 9 of 36(25%)mixed maize female and male elite inbred genotypes,*** of edited genotypes for the regenerated individuals identified over 800 distinct edits at the Determinate1(Dt1)locus in samples from 101 soybean genotypes and 95 distinct Brown midrib3(Bm3)edits in samples from 17 maize *** results illustrate how TREDMIL can help accelerate the development and deployment of customized crop varieties for future precision breeding.

关键词： Maize Soybean Seed embryo explants TREDMIL Genetic transformation Genome editing

Low-loss and polarization insensitive 32×4 optical switch for ROADM applications

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Light(Science & Applications) 2024年第5期13卷 875-884页

作者： Xiaotian Zhu Xiang Wang Yanlu Huang Liyan Wu Chunfei Zhao Mingzhu Xiao Luyi Wang Roy Davidson Yanni Ou brent E.Little Sai T.Chu Department of Physics City University of Hong KongTat Chee AvenueHong KongChina. QXP Technologies Inc. NO.15th Shanglinyuan 1st RoadXi’anShaanxi 710119China. State Key Laboratory of Information of Photonics and Optical Communications School of Electronic EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China

Integrated switches play a crucial role in the development of reconfigurable optical add-drop multiplexers(ROADMs)that have greater flexibility and compactness,ultimately leading to robust single-chip *** decades of research on switches with various structures and platforms,achieving a balance between dense integration,low insertion loss(IL),and polarization-dependent loss(PDL)remains a significant *** this paper,we propose and demonstrate a 32×4 optical switch using high-index doped silica glass(HDSG)for ROADM *** switch is designed to route any of the 32 inputs to the express ports or drop any channels from 32 inputs to the target 4 drop ports or add any of the 4 ports to any of the 32 express *** switch comprises 188 MachZehnder Interferometer(MZI)type switch elements,88 optical vias for the 44 optical bridges,and 618 waveguidewaveguide crossings with three-dimensional(3D)*** 1550 nm,the fiber-to-fiber loss for each express channel is below 2 dB,and across the C and L bands,below 3 *** each input channel to all 4 drop/add channels at 1550 nm,the loss is less than 3.5 dB and less than 5 dB across the C and L *** PDLs for all express and input channels to the 4 drop/add channels are below 0.3 dB over the C band,and the crosstalk is under−50 dB for both the C and L bands.

关键词： polarization ROADM optical