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Longwall automation: Delivering enabling technology to achieve safer and more productive underground mining

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International Journal of Mining Science and Technology 2015年第6期25卷 865-876页

作者： Ralston Jonathon C. Reid david C. Dunn Mark T. Hainsworth david w. Coal Mining Research Program CSIRO Energy

The ongoing need to deliver improved safety, productivity and environmental benefit in coal mining presents an open challenge as well as a powerful incentive to develop new and improved *** paper assesses the critical role that enabling technologies have played in the delivery of remote and automated capability for longwall mining. A brief historical account is given to highlight key technical contributions which have influenced the direction and development of present-day longwall technology. The current state of longwall automation is discussed with particular attention drawn to the technologies that enable automated capability. Outcomes are presented from an independently conducted case study that assessed the impact that CSIRO's LASC longwall automation research has made to the longwall mining industry in Australia. Importantly, this study reveals how uptake of this innovative technology has significantly benefitted coal mine productivity, improved working conditions for personnel and enhanced environmental outcomes. These benefits have been widely adopted with CSIRO automation technology being used in 60 per cent of all Australian underground *** deployment of the technology is also emerging. The paper concludes with future challenges and opportunities to highlight the ongoing scope for longwall automation research and development.

关键词：远程自动化开采技术长壁工作面安全性地下开采 CSIRO 研究与开发长壁开采

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Coherent and semicoherent α/β interfaces in titanium: structure, thermodynamics, migration

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npj Computational Materials 2023年第1期9卷 146-156页

作者： Siqi wang Tongqi wen Jian Han david J.Srolovitz Department of Materials Science and Engineering City University of Hong KongHong Kong SARChina Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong SARChina

Theα/βinterface is central to the microstructure and mechanical properties of titanium *** investigate the structure,thermodynamics and migration of the coherent and semicoherent Tiα/βinterfaces as a function of temperature and misfit strain via molecular dynamics(MD)simulations,thermodynamic integration and an accurate,DFT-trained Deep *** structure of an equilibrium semicoherent interface consists of an array of steps,an array of misfit dislocations,and coherent *** determines the dislocation and step(disconnection)array structure and habit *** MD simulations show the detailed interface morphology dictated by intersecting disconnection *** steps are shown to facilitateα/βinterface migration,while the misfit dislocations lead to interface drag;the drag mechanism is different depending on the direction of interface *** results are used to predict the nature ofαphase nucleation on cooling through theα-βphase transition.

关键词： semicoherent microstructure interface

Drag on Hydroid-Fouled Nets – An Experimental Approach

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China Ocean Engineering 2015年第3期29卷 369-389页

作者： Pl LADER david w. FREDRIKSSON Jana GUENTHER Zsolt VOLENT Nina BLOCHER david KRISTIANSEN Lars GANSEL Jud DECEw SINTEF Fisheries and Aquaculture United States Naval Academy University of New Hampshire

The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts： firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant（1.4 hydroids/mm and 0.29 mm, respectively）, while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal（Gaussian） distributed. Replicas of twines with three different levels of hydroid growth were made（1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm）, and the drag on these twines was measured at different towing velocities（0.1 to 1.4 m/s） and with different twine configurations. For the twine with the shortest hydroids（9 mm）, the drag was from 1.5 times（Re=4000） to 2.2 times（Re=1000） the drag on a clean twine. For the longest hydroids（21 mm）, the drag was 2 times and 3.8 times, respectively.

关键词： hydroid biofouling aquaculture net hydrodynamic drag

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Quantifying local fire regimes using the Landsat data-archive:a conceptual framework to derive detailed fire pattern metrics from pixel-level information

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International Journal of Digital Earth 2019年第5期12卷 544-565页

作者： Ignacio San-Miguel david w.Andison Nicholas C.Coops Integrated Remote Sensing Studio Department of Forest Resources ManagementUniversity of British ColumbiaVancouverBCCanada Bandaloop Landscape-Ecosystem Services North VancouverBCCanada

Free and open access to the Landsat archive has enabled the detection and delineation of an unprecedented number of fire events across the *** the availability and potential of these data,few studies have analysed residual vegetation patterns and/or partial mortality of fire across the Canadian boreal forest,and those available,are either incomplete or ***,they all differ in the methods and spatial language,which makes it difficult for managers to interpret fire patterns over large *** is an urgent need for methods to help unify fire pattern observations across the Canadian boreal *** study explores the capacity of the Landsat data archive when coupled with a recently developed fire mapping approach and a robust spatial language to characterize and compare tree mortality patterns across the boreal plains ecozone,*** 507 fires 2.5 Mha mapped,this study represents the most comprehensive analysis of mortality patterns for study *** from this demonstration generated an accurate characterization of the fire patterns the various ecoregions based on seven key fire *** comparison between ecoregions revealed differences in the amount of residual vegetation,which in turn suggested various climate,topography and/or vegetation ecosystem drivers.

关键词： Fire emulation historical range of variability landscape metrics fire patterns disturbance-based management

Machine learning and data-driven prediction of pore pressure from geophysical logs:A case study for the Mangahewa gas field,New Zealand

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1799-1809页

作者： Ahmed E.Radwan david A.wood Ahmed A.Radwan Faculty of Geography and Geology Institute of Geological SciencesJagiellonian UniversityKraków30-387Poland Exploration Department Gulf of Suez Petroleum CompanyCairoEgypt DwA Energy Limited LincolnUK Department of Geology Faculty of ScienceAl-Azhar UniversityAssiut BranchAssiut71524Egypt

Pore pressure is an essential parameter for establishing reservoir conditions,geological interpretation and drilling *** pressure prediction depends on information from various geophysical logs,seismic,and direct down-hole pressure ***,a level of uncertainty accompanies the prediction of pore pressure because insufficient information is usually recorded in many *** machine learning(ML)algorithms can decrease the level of uncertainty of pore pressure prediction uncertainty in cases where available information is *** this research,several ML techniques are applied to predict pore pressure through the over-pressured Eocene reservoir section penetrated by four wells in the Mangahewa gas field,New *** predictions substantially outperform,in terms of prediction performance,those generated using a multiple linear regression(MLR)*** geophysical logs used as input variables are sonic,temperature and density logs,and some direct pore pressure measurements were available at the reservoir level to calibrate the predictions.A total of 25,935 data records involving six well-log input variables were evaluated across the four *** ML methods achieved credible levels of pore pressure prediction *** most accurate models for predicting pore pressure in individual wells on a supervised basis are decision tree(DT),adaboost(ADA),random forest(RF)and transparent open box(TOB).The DT achieved root mean square error(RMSE)ranging from 0.25 psi to 14.71 psi for the four *** trained models were less accurate when deployed on a semi-supervised basis to predict pore pressure in the other *** two wells(Mangahewa-03 and Mangahewa-06),semi-supervised prediction achieved acceptable prediction performance of RMSE of 130—140 psi;while for the other wells,semi-supervised prediction performance was reduced to RMSE>300 *** results suggest that these models can be used to predict pore pressure in nearby locat

关键词： Machine learning(ML) Pore pressure Overburden well-log derived predictions Overpressure

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Harnessing the synergy of perfusable muscle flap matrix and adipose-derived stem cells for prevascularization and macrophage polarization to reconstruct volumetric muscle loss

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Bioactive Materials 2023年第4期22卷 588-614页

作者： Qixu Zhang Yulun Chiu Youbai Chen Yewen wu Lina w.Dunne Rene D.Largo Edward I.Chang david M.Adelman Mark V.Schaverien Charles E.Butler Department of Plastic Surgery The University of Texas MD Anderson Cancer CenterHoustonTX77030USA Department of Melanoma Medical Oncology The University of Texas MD Anderson Cancer CenterHoustonTX77030USA Department of Plastic Surgery Chinese PLA General HospitalBeijing100853China

Muscle flaps must have a strong vascular network to support a large tissue volume and ensure successful *** developed porcine stomach musculofascial flap matrix(PDSF)comprising extracellular matrix(ECM)and intact *** had a dominant vascular pedicle,microcirculatory vessels,a nerve network,well-retained 3-dimensional(3D)nanofibrous ECM structures,and no allo-or ***-depth proteomic analysis demonstrated that PDSF was composed of core matrisome proteins(e.g.,collagens,glycoproteins,proteoglycans,and ECM regulators)that,as shown by Gene Ontology term enrichment analysis,are functionally related to musculofascial biological ***,PDSF􀀀human adipose-derived stem cell(hASC)synergy not only induced monocytes towards IL-10􀀀producing M2 macrophage polarization through the enhancement of hASCs’paracrine effect but also promoted the proliferation and interconnection of both human skeletal muscle myoblasts(HSMMs)and human umbilical vein endothelial cells(HUVECs)in static triculture ***,PDSF was successfully prevascularized through a dynamic perfusion coculture of hASCs and HUVECs,which integrated with PDSF and induced the maturation of vascular networks in *** a xenotransplantation model,PDSF demonstrated myoconductive and immunomodulatory properties associated with the predominance of M2 macrophages and regulatory T *** a volumetric muscle loss(VML)model,prevascularized PDSF augmented neovascularization and constructive remodeling,which was characterized by the predominant infiltration of M2 macrophages and significant musculofascial tissue *** results indicate that hASCs’integration with PDSF enhances the cells’dual function in immunomodulation and *** in part to this PDSF-hASC synergy,our platform shows promise for vascularized muscle flap engineering for VML reconstruction.

关键词： Muscle flap fabrication Extracellular matrix Decellularization Vascularization Macrophage polarization Volumetric muscle loss

Channel capacity investigation of a linear massive MIMO system using spherical wave model in LOS scenarios

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Science China(Information Sciences) 2016年第2期59卷 45-59页

作者： Liu LIU david w.MATOLAK Cheng TAO Yongzhi LI Bo AI Houjin CHEN Institute of Broadband wireless Mobile Communications Beijing Jiaotong University Department of Electrical Engineering University of South Carolina National Mobile Communications Research Laboratory Southeast University

Massive multiple-input multiple-output(MIMO) is a key technology for the 5th generation(5G)of wireless communication systems. The traditional plane wave channel model(PwM) is often not suitable for the large antenna structure, and in certain cases should be replaced by the more accurate spherical wave model(SwM). By using the spherical wave characterization method, this paper investigates the channel capacity performance of a linear massive MIMO system in line-of-sight(LOS) scenarios. Two types of access settings, the point to point(PTP) system and multi-user(MU) system, are considered. In the PTP setting, a geometrical optimization is performed to obtain configurations that are able to generate a full rank channel matrix for a linear massive MIMO system, which yields full spatial diversity even in LOS scenarios. Compared with the approximate and commonly applied rank-1 PwM, this is very useful for fixed wireless access and radio relay systems requiring high throughput. For the MU case, we compare the eigenvalue distributions of the LOS channels using the plane wave and spherical wave characterization method, and sum rate results are obtained by Monte Carlo simulations. The results show that MU systems using the more realistic and accurate SwM can achieve a higher sum rate than results from the PwM. This is beneficial and informative when designing massive MIMO wireless networks.

关键词： massive MIMO channel model plane wave model spherical wave model channel capacity

Convergence of ADMM for multi-block nonconvex separable optimization models

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Frontiers of Mathematics in China 2017年第5期12卷 1139-1162页

作者： Ke GUO Deren HAN david Z. w. wANG Tingting wU School of Mathematical Sciences and Key Laboratory for NSLSCS of Jiangsu Province Nanjing Normal University Nanjing 210023 China School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore 639798 Singapore School of Science Nanjing University of Posts and Telecommunications Nanjing 210023China

For solving minimization problems whose objective function is the sum of two functions without coupled variables and the constrained function is linear, the alternating direction method of multipliers （ADMM） has exhibited its efficiency and its convergence is well understood. when either the involved number of separable functions is more than two, or there is a nonconvex function~ ADMM or its direct extended version may not converge. In this paper, we consider the multi-block *** optimization problems with linear constraints and absence of convexity of the involved component functions. Under the assumption that the associated function satisfies the Kurdyka- Lojasiewicz inequality, we prove that any cluster point of the iterative sequence generated by ADMM is a critical point, under the mild condition that the penalty parameter is sufficiently large. we also present some sufficient conditions guaranteeing the sublinear and linear rate of convergence of the algorithm.

关键词： Nonconvex optimization separable structure alternating directionmethod of rnultip!iers (.ADMM) Kurdyka-Lojasiewicz inequality

PRISMS-PF:A general framework for phase-field modeling with a matrix-free finite element method

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npj Computational Materials 2020年第1期6卷 1421-1432页

作者： Stephen Dewitt Shiva Rudraraju david Montiel w.Beck Andrews Katsuyo Thornton University of Michigan Department of Materials Science and Engineering2300 Hayward St.Ann ArborMI 48109USA University of Michigan Department of Mechanical Engineering2350 Hayward St.Ann ArborMI 48109USA University of wisconsin MadisonWI 53706USA

A new phase-field modeling framework with an emphasis on performance,flexibility,and ease of use is *** among the strategies employed to fulfill these objectives are the use of a matrix-free finite element method and a modular,application-centric code *** approach is implemented in the new open-source PRISMS-PF *** performance is enabled by the combination of a matrix-free variant of the finite element method with adaptive mesh refinement,explicit time integration,and multilevel *** testing with a particle growth problem shows PRISMS-PF with adaptive mesh refinement and higher-order elements to be up to 12 times faster than a finite difference code employing a second-order-accurate spatial discretization and first-order-accurate explicit time integration.

关键词： structure finite element