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A discrete model for prediction of radon flux from fractured rocks

Journal of Rock.m.chanics and Geotechnical Engineering 2018年第5期10卷 879-892页

作者： k.m. ajayi k. Shahbazi R Tukkaraja k. katzenstein Department of mechanical Engineering South Dakota School of Mines and Technology Rapid City SD 57701 USA b Department of mining Engineering and management South Dakota School of Mines and Technology Rapid City SD 57701 USA Department of Geology and Geological Engineering South Dakota School of Mines and Technology Rapid City SD 57701 USA

Prediction of radon flux from the fractured zone of a propagating cave mine is basically associated with uncertainty and complexity. For instance, there is restricted access to these zones for field measure- ments, and it is quite difficult to replicate the complex nature of both natural and induced fractures in these zones in laboratory studies. Hence, a technique for predicting radon flux from a fractured rock using a discrete fracture network （DFN） model is developed to address these difficulties. This model quantifies the contribution of fractures to the total radon flux, and estimates the fracture density from a measured radon flux considering the effects of advection, diffusion, as well as radon generation and decay. Radon generation and decay are classified as reaction processes. Therefore, the equation solved is termed as the advection-diffusion-reaction equation （ADRE）. Peclet number （Pe）, a conventional dimensionless parameter that indicates the ratio of mass transport by advection to diffusion, is used to classify the transport regimes. The results show that the proposed model effectively predicts radon flux from a fractured rock. An increase in fracture density for a rock sample with uniformly distributed radon generation rate can elevate radon flux significantly compared with another rock sample with an equivalent increase in radon generation rate. In addition to Pe, two other independent dimensionless parameters （derived for radon transport through fractures） significantly affect radon dimensionless flux. Findings provide insight into radon transport through fractured rocks and can be used to improve radon control measures for proactive mitigation.

关键词： Radon mass flux Radon dimensionless flux Stochastic model Discrete fracture network (DFN) Caving mining method Fractured rocks

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Referring Expressions: A Unified Approach

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外国语 2001年第2期24卷 1-22页

作者： k.m. Jaszczolt Department of Linguistics University of Cambridge

0. Introduction

关键词：语言学语言表达方式语言交际语言目的

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Transport model for shale gas well leakage through the surrounding fractured zones of a longwall mine

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International Journal of mining Science and Technology 2020年第5期30卷 635-641页

作者： kayode m.ajayi Steven J.Schatzel Centers for Disease Control and Prevention National Institute for Occupational Safety and HealthPittsburghPA 15236USA

The environmental risks associated with casing deformation in unconventional(shale)gas wells positioned in abutment pillars of longwall mines is a concern to many in the mining and gas well *** the recent interest in shale exploration and the proximity to longwall mining in Southwestern Pennsylvania,the risk to mine workers could be catastrophic as fractures in surrounding strata create pathways for transport of leaked ***,this research by the National Institute for Occupational Safety and Health(NIOSH)presents an analytical model of the gas transport through fractures in a low permeable *** derived equations are used to conduct parametric studies of specific transport conditions to understand the influence of stratum geology,fracture lengths,and the leaked gas properties on subsurface *** results indicated that the prediction that the subsurface gas flux decreases with an increase in fracture length is specifically for a non-gassy *** sub-transport trend could be significantly impacted by the stratum gas generation rate within specific fracture lengths,which emphasized the importance of the stratum *** findings provide new insights for improved understanding of subsurface gas transport to ensure mine safety.

关键词： Subsurface gas transport Longwall mining Shale gas well Analytical modeling Environmental risk Shale gas casing failure

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Atomistic Simulation of the Orientation-dependent Plastic Deformation mechanisms of Iron Nanopillars

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Journal of materials Science & Technology 2012年第2期28卷 164-168页

作者： Y. Zhang D.J. Yu k.m. Wang Anshan-Normal University 43 Pingan Street Anshanll4005 China University of Science and Technology LiaoNing Anshanll4051 China

Tensile tests were performed on iron nanopillars oriented along [001] and [110] directions at a constant temperature of 300 k through molecular dynamics simulations with an embedded-atom interatomic potential for iron. The nanopillars were stretched until yielding to investigate the onset of their plastic deformation behaviors. Yielding was found to occur through two different mechanisms for [001] and [110] tensions. In the former case, plastic deformation is initiated by dislocation nucleation at the edges of the nanopillar, whereas in the latter case by phase transformation inside the nanopillar. The details during the onset of plastic deformation under the two different orientations were analyzed. The varying mechanisms during plastic deformation initiation are bound to influence the mechanical behavior of such nanoscale materials, especially those strongly textured.

关键词： Iron molecular dynamics simulation Nanopillar Plastic deformation

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Buried channels provide keys to infer Quaternary stratigraphic and paleo-environmental changes:A case study from the west coast of India

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Geoscience Frontiers 2019年第4期10卷 1577-1595页

作者： k.m. Dubey A.k.Chaubey V.P. mahale S.m. karisiddaiah CSIR-National Institute of Oceanography Dona PaulaGoa403004India CSIR-National Institute of Oceanography Regional CentreLokhandwala RoadAndheri (West)MumbaiMaharashtra400053India Department of marine Sciences Goa UniversityTaleigao PlateauGoa403206India

High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf *** data revealed characteristic channel incisions beneath 4-15 m thick sediment layer and corresponds to multi cycle *** analysis of these incision signatures reveals three prominent subaerial unconformities S6,S7 and *** unconformities were exposed during the last glacial,penultimate glacial(mIS-6)and prior to penultimate glacial(mIS-8)*** the basis of interpreted age of subaerial unconformities and differences in their morphological features,observed channel incisions have been divided grossly into three phases of ***-1 incisions are older than^330 kyr BP,whereas,incisions of Phase-2 and Phase-3 correspond to^320-125 kyr BP and^115-10 kyr BP *** form of these incisions varied from a straight channel type to ingrown meander and then to anastomosing channel *** channels meet at the confluence of present-day mandovi and Zuari *** confluence point has varied in due course of time because of cyclic incision and burial with repeated sea level *** preserved main channel width varies from^100 m to 1000 *** maximum channel depth reaches up to^35 *** of quantitative and qualitative morphologic results of different phases of incisions suggest that Phase-2 channels had^33%more mean bank full discharge than that of the Phase-3 ***-2 incisions had been carved in higher hydraulic energy condition as compared to Phase-3 incisions implying that the Indian summer monsoon was better during formative stages of Phase-2 incisions.

关键词： Buried channels Glacial period Indian summer monsoon Quaternary sea-level Subaerial unconformity West coast of India

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Efficacy of antimicrobials in preventing resistance in solid organ transplant recipients:A systematic review of clinical trials

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World Journal of Transplantation 2025年第1期15卷 156-164页

作者： Carlos m Ardila Pradeep k Yadalam Jaime Ramírez-Arbelaez Department of Basic Sciences Faculty of Dentistry Biomedical Stomatology Research GroupUniversidad de Antioquia U de AMedellín 0057Colombia Department of Postdoctoral Program CIFE University CenterCuernavaca 62330MorelosMexico Department of Periodontics Saveetha Dental CollegeSaveetha Institute of Medical and HealthSIMATSSaveetha UniversityChennai 600077Tamil NaduIndia Department of Transplantation Hospital San Vicente FundaciónRionegro 054047Colombia

BACkGROUND In the absence of effective antimicrobials,transplant surgery is not viable,and antirejection immunosuppressants cannot be administered,as resistant infections compromise the life-saving goal of organ *** To evaluate the efficacy of antimicrobials in preventing resistance in solid organ transplant *** A systematic review was conducted using a search methodology consistent with the preferred reporting items for systematic reviews and *** review included randomized clinical trials that evaluated the efficacy of antimicrobial agents(prophylactic or therapeutic)aimed at preventing antimicrobial *** search strategy involved analyzing multiple databases,including Pubmed/mEDLINE,Web of Science,Embase,Scopus,and SciELO,as well as examining gray literature sources on Google Scholar.A comprehensive electronic database search was conducted from the databases’inception until may 2024,with no language *** After the final phase of the eligibility assessment,this systematic review ultimate-ly included 7 articles.A total of 2318 patients were *** most studied microorganisms were cytomegalovirus,although vancomycinresistant enterococci,Clostridioides difficile,and multidrug-resistant Enterobacterales were also *** antimicrobials used in the interventions were mainly maribavir,valganciclovir,gancic-lovir,and *** concern,all clinical trials showed significant proportions of resistant microorga-nisms after the interventions,with no statistically significant differences between the groups(mean resistance 13.47%vs 14.39%),except for two studies that demonstrated greater efficacy of maribavir and valganciclovir(mean resistance 22.2%vs 41.1%in the control group;Pmicrobial-resistant microor

关键词： Antimicrobial resistance Antimicrobials Antivirals Solid organ transplant recipients Infections microorganisms Cytomegalovirus

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Total synthesis of(-)-goniopypyrone

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Chinese Journal of Chemistry 1993年第5期11卷 479-480页

作者： SHING Tony k.m. Department of Chemistry The Chinese University of Hong KongShatinH.K.

Recently,three novel styryl-lactones,goniofufurone,goniopypyrone,and 8-acetylgo-niotriol,which are cytotoxic to human tumor cells,have been isolated from the stembark of Goniothalamus *** these lactones,goniopypyrone ... 详细信息

关键词： Total synthesis of goniopypyrone THF

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Prediction of airway resistance in panel cave mines using a discrete and continuum model

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International Journal of mining Science and Technology 2019年第5期29卷 781-784页

作者： kayode m.ajayi khosro Shahbazi Purushotham Tukkaraja kurt katzenstein Department of mechanical Engineering SDSMTRapid CitySD 57701USA Department of mining Engineering and management SDSMTSD 57701USA Department of Geology and Geological Engineering SDSMTSD 57701USA

The configuration of an airway(or production drift)in panel cave mines is different from the typical(straight)mine airway *** drawpoints are connected to the airway(cross-cuts),which allows airflow from the cave into the airway or air loss from the airway into the cave due to the ventilation approach and cave *** affect airflow in the production drifts,but it is difficult to investigate these conditions from field or laboratory scaled ***,this study develops discrete and continuum computational fluid dynamics(CFD)models to study the effects of the ventilation approach and cave porosity on the airway *** findings show that:with active undercut ventilation,a unique resistance model is required for the airway in panel cave mines;and an increase in cave porosity decreases the drift’s *** findings provide essential tools for a panel cave ventilation design.

关键词： Airway resistance Caving mining method Panel cave mines Broken rocks Porous media Computational fluid dynamics(CFD)

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Crystallization inhibition of an amorphous sucrose system using raffinose

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2006年第2期7卷 85-89页

作者： LEINEN k.m. LABUZA T.P. Department of Food Science and Nutrition University of Minnesota St. Paul MN 55108 USA

The shelf life of pure amorphous sucrose systems, such as cotton candy, can be very short. Previous studies have shown that amorphous sucrose systems held above the glass transition temperature will collapse and crystallize. One study, however, showed that adding a small percent of another type of sugar, such as trehalose, to sucrose can extend the shelf life of the amorphous system by slowing crystallization. This study explores the hypothesis that raffinose increases the stability of an amorphous sucrose system. Cotton candy at 5 wt% raffinose and 95 wt% sucrose was made and stored at room temperature and three different relative humidities (%RH) 11%RH, 33%RH, and 43%RH. XRD patterns, and glass transition temperatures were obtained to determine the stability as a function of %RH. The data collected showed that raffinose slows sucrose crystallization in a low moisture amorphous state above the glass transition temperature and therefore improves the stability of amorphous sucrose systems.

关键词： Crystallization Amorphous sucrose system Raffinose

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Dispersion sensitivity analysis&consistency im provement of APFSDS

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Defence Technology（防务技术） 2017年第4期13卷 316-322页

作者： Sangeeta Sharma Panda L.k. Gite A. Anandaraj R.S. Deodhar D.k. Joshi k.m. Rajan Armament Research Development Establishment (ARDE) Defence Research Development Organization Ministry of Defence Government of India Pashan Pune Maharashtra 411 021 India

The purpose of this study is to investigate and quantify some possible sources of dispersion of 120 mm APFSDS tank ammunition both experimentally and *** paper aims to point out the most influential source during In-Bore Balloting motion phase as well as in External Ballistics phase of the ammunition and quantifies its effect on *** obtained from flight trials is critically analysed and parameters affecting dispersion such as initial yaw/pitch rates,yaw/pitch dampening,plane start angle,launch spin,clearance,centre of gravity shift,dynamic imbalance angle,cross wind,*** observed and,later on,studied in detail by extensive External Ballistics monte Carlo(EBmC)simulation and Six Degree of Freedom(6-DOF)trajectory *** Bore Balloting motion simulation shows that reduction in residual spin by about 5%results in drastic56%reduction in first maximum yaw.A correlation between first maximum yaw and residual spin is *** of data analysis are used in design modification for existing *** of designs are evaluated numerically before freezing five designs for further *** designs are critically assessed in terms of their comparative performance during In-bore travel&external ballistics *** are validated by free flight trials for the finalised design.

关键词： APFSDS Dispersion Consistency Accuracy Yaw rate Spin muzzle jump factor In-bore dynamics monte Carlo simulation

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