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Case study and design of steel set support for aged belt entry rehabilitation

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International Journal of Mining Science and Technology 2018年第1期28卷 101-106页

作者： kevin Jinrong Ma John Stankus Keystone Mining Services LLC

In order to access remote reserve areas, some *** mines have to maintain aged underground entries for a great ***, high humidity, warm temperature, and time dependent deterioration can cause progressive roof deterioration and unexpected roof falls, and pose a great challenge to ground control *** an active belt structure in place and limited space, re-bolting becomes very costly, less effective,and, sometimes, impractical and *** gain long-term entry stability and serviceability, operators typically rehabilitate the aged belt entries by installing standing steel set *** the last several years,Keystone Mining Services, LLC,(KMS) has assisted many coal mines with their belt entry rehabilitation projects, evaluated the ground condition of various aged belt entries, and designed different standing steel set support *** paper presents a case study of a large-scale roof fall that occurred at an aged belt entry in a mine located in an eastern coalfield, analyzes root causes of excessive deformation of square sets that were installed in an adjacent entry, evaluates the adequacy of an existing rehabilitation square set, and develops remedial recommendations for future rehabilitation *** on the case study, the paper outlines design guidelines for rehabilitation steel sets that include field evaluation, engineering considerations, design assumptions, steel structural analysis, and field installation quality control.

关键词： Coal mine Roof fall Belt entry Rehabilitation Steel set support

JUMPING INSTABILITIES IN THE POST-BUCKLING OF A BEAM ON A PARTIAL NONLINEAR FOUNDATION

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Acta Mechanica Solida Sinica 2013年第5期26卷 500-513页

作者： Yin Zhang kevin D Murphy State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Department of Mechanical Engineering University of Connecticut

Mode jumping is an instability phenomenon in the post-buckling region, which causes a sudden change in the equilibrium configuration and is thus harmful to structure. The con- figuration of a partial elastic foundation can directly induce mode coupling from the buckling stage and through the whole post-buckling region. The mode coupling effect due to the configuration of partial foundation on mode jumping is investigated and demonstrated to be an important factor of determining mode jumping. By properly choosing the partial elastic foundation configuration, mode jumping can be avoided.

关键词： instability mode jumping tertiary jumping buckling beam elastic foundation

High Resolution Global Modeling of the Atmospheric Circulation

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Advances in Atmospheric Sciences 2006年第6期23卷 842-856页

作者： kevin HAMILTON International Pacific Research Center University of Hawaii at Manoa HonoluluHawaii 96822USA

An informal review is presented of recent developments in numerical simulation of the global atmospheric circulation with very fine numerical resolution models, The focus is on results obtained recently with versions of the GFDL SKYHI model and the Atmospheric Model for the Earth Simulator （AFES） global atmospheric models. These models have been run with effective horizontal grid resolution of -10-40 km and fine vertical resolution. The results presented demonstrate the utility of such models for the study of a diverse range of phenomena, Specifically the models are shown to simulate the development of tropical cyclones with peak winds and minimum central pressures comparable to those of the most intense hurricanes actually observed, More fundamentally, the spectrum of energy content in the mesoscale in the flow can be reproduced by these models down to near the smallest explicitly-resolved horizontal scales, in the middle atmosphere it is shown that increasing horizontal resolution can lead to significantly improved overall simulation of the global-scale circulation, The application of the models to two specific problems requiring very fine resolution global will be discussed, The spatial and temporal variability of the vertical eddy flux of zonal momentum associated with gravity waves near the tropopause is evaluated in the very fine resolution AFES model, This is a subject of great importance for understanding and modelling the flow in the middle atmosphere, Then the simulation of the small scale variations of the semidiurnal surface pressure oscillation is analyzed, and the signature of significant topographic modulation of the semidiurnal atmospheric tide is identified.

关键词： general circulation model mesoscale simulation gravity waves atmospheric tides

Preliminary studies on the stability of arsenolipids:Implications for sample handling and analysis

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Journal of Environmental Sciences 2016年第11期28卷 97-103页

作者： Muslim Khan kevin A.Francesconi Institute of Chemistry-Analytical Chemistry University of Graz

Human health risk assessments concerning arsenic are now estimating exposure through food in addition to exposure through drinking water. Intrinsic to this assessment is sample handling and preparation that maintains the arsenic species in the form that they occur in foods. We investigated the stability of three arsenolipids（two arsenic fatty acids, As FA-362 and As FA-388, and one arsenic hydrocarbon As HC-332）, common constituents of fish and algae, relevant to sample storage and transport, and to their preparation for quantitative measurements. The fate of the arsenolipids was followed by high performance liquid chromatography/electrospray triple quadruple mass spectrometry（HPLC/ESIMS） *** of the compounds dry as pure compounds or mixed in fish oil at up to 60？C did not result in significant changes to the compounds, although losses were observed by apparent adsorption onto the plastic walls of the polypropylene tubes. No losses occurred when the experiment was repeated with glass tubes. When the compounds were stored in ethanol for up to 15 days under acidic, neutral, or alkaline conditions（each at room temperature）, no significant decomposition was observed, although esterification of the fatty acids occurred at low p H. The compounds were also stable during a sample preparation step involving passage through a small silica column. The results indicate that these typical arsenolipids are stable when stored in glass at temperatures up to 60？C for at least 2 days, and that,consequently, samples of food or extracts thereof can be transported dry at ambient temperatures, i.e. without the need for cool conditions.

关键词： Arsenolipids Stability Mass spectrometry

Global aspirations, local realities: the role of social science research in controlling neglected tropical diseases

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Infectious Diseases of Poverty 2014年第1期3卷 310-324页

作者： kevin Bardosh Centre of African Studies School of Social and Political ScienceCollege of Humanities and Social ScienceThe University of Edinburgh58 George SquareEdinburgh EH89LDUK Division of Pathway Medicine and Centre for Infectious Diseases School of Biomedical SciencesCollege of Medicine and Veterinary MedicineThe University of EdinburghChancellor’s Building49 Little France CrescentEdinburgh EH164SBUK

Neglected Tropical Diseases(NTDs)are both drivers and manifestations of poverty and social *** advocacy efforts since the mid-2000s have led to ambitious new control and elimination targets set for 2020 by the World Health *** these global aspirations represent significant policy momentum,there are multifaceted challenges in controlling infectious diseases in resource-poor local contexts that need to be acknowledged,understood and *** a number of recent publications have emphasised the“neglected”status of applied social science research on *** light of the 2020 targets,this paper explores the social science/NTD literature and unpacks some of the ways in which social inquiry can help support effective and sustainable *** priority areas are discussed,including on policy processes,health systems capacity,compliance and resistance to interventions,education and behaviour change,and community *** paper shows that despite the multifaceted value of having anthropological and sociological perspectives integrated into NTD programmes,contemporary efforts underutilise this *** is reflective of the dominance of top-down information flows and technocratic approaches in global *** counter this tendency,social research needs to be more than an afterthought;integrating social inquiry into the planning,monitoring and evaluating process will help ensure that flexibility and adaptability to local realities are built into *** emphasis on social science perspectives can also help link NTD control to broader social determinants of health,especially important given the major social and economic inequalities that continue to underpin transmission in endemic countries.

关键词： Neglected tropical diseases Applied social sciences Implementation research Social determinants Community participation Policy Global health Sociology Anthropology

Experimental study on modification of water-based filtercake to improve the bonding strength at the wellbore cement-formation interface

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Petroleum Research 2023年第4期8卷 531-540页

作者： kevin Nsolloh Lichinga Department of Engineering Development Tanzania Industrial Research and Development Organization(TIRDO)PO Box 23235Dar es SalaamTanzania Department of Petroleum Engineering Faculty of Earth Resources for Oil Well Cement Research and TestingNo.388Lumo RoadHongshan DistrictWuhanChina University of GeosciencesWuhan430074PR China

The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface(WCFI),so as to ensure long-term zonal isolation throughout the lifecycle of the well by using NsO solution as filtercake modifier which was developed in the *** to designed experimental method and API RP 10,the effectiveness of filtercake modifier(NSO)on the bonding strength at the WCFI was assessed by using designed simulated wellbore as sandstone *** experimental results indicated that the samples which were treated with NsO solution had higher bond strength over untreated *** strength generally increased with curing period as for treated samples,0.198,0.374,0.433 and 0.473 MPa for 3,7,15,and 30 days respectively while for the untreated samples the bond strength were 0.050,0.070,0.81 and 0.100 MPa for the same *** water-based filtercake modification techniques had significantly enhanced the bonding strength of WCFI by increasing rates above 296%.Improvement of bond strength to the treated sample was due to filtercake modification as a result of formation of cementitious material as revealed in FTIR spectral such as Calcium-Silicate-Hydrate(C-S-H)and other geopolymers like Calcium-Aluminium-Silicate-Hydrate(C-A-S-H)and Sodium-Aluminium-Silicate-Hydrate(N-A-S-H)along the interface which filled the existed pores hence reducing porosity hence high strength of *** low transmittance value for the NsO treated samples revealed that there were more cementitious materials existing at the WCFI which led to improvement of bonding strength as compared to the untreated *** lower/poor bond strength for the untreated samples is due to existence of untreated,thick water-based filtercake films at WCFI,which prevented the complete hydration process between rock grains and cement slurry components to make chemical binder of cement slurry material and formation.2022 The Authors.P

关键词： Geopolymer Bond strength Water-based mud Wellbore cement-formation interface NSO

Discrete element modelling of the quasi-static uniaxial compression of individual infant formula agglomerates

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Particuology 2012年第5期10卷 523-531页

作者： kevin J.Hanley Catherine O'Sullivan Edmond P.Byrne kevin Cronin Department of Process and Chemical Engineering University College CorkCorkIreland Department of Civil and Environmental Engineering Skempton BuildingImperial College LondonLondon SW7 2AZ United Kingdom

Infant formula is usually produced in an agglomerated powder form. These agglomerates are subjected to many transient forces following their manufacture. These can be difficult to quantify experimentally because of their small magnitudes and short durations, Numerical models have the potential to address this gap in the experimental data. The objective of the research described here was to calibrate a discrete element model for these agglomerates using experimental data obtained for quasi-static loading, and to use this model to study the mechanics of the particle response in detail. The Taguchi method was previously proposed as a viable calibration approach for discrete element models. In this work, the method was assessed for calibration of the model parameters （e.g., bond stiffnesses and strengths） considering three responses： the force at failure, strain at failure and agglomerate stiffness. The Weibull moduli for the simulation results and the experimental data were almost identical following calibration and the 37% characteristic stresses were similar. An analysis of the energy terms in the model provided useful insight into the model response. The bond energy and the normal force exerted on the platens were strongly correlated, and bond breakage events coincided with the highest energy dissipation rates.

关键词： Discrete element modellingUniaxial compressionQuasi-static crushingSimulationGranular materialsTaguchi methods

FEARCF a multidimensional free energy method for investigating conformational landscapes and chemical reaction mechanisms

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Science China Chemistry 2011年第12期54卷 1962-1973页

作者： NAIDOO kevin J. Scientific Computing Research Unit and Department of Chemistry University of Cape Town

The development and implementation of a computational method able to produce free energies in multiple dimensions,descriptively named the free energies from adaptive reaction coordinate forces(FEARCF) method is described in this *** the method can be used to calculate free energies of association,conformation and reactivity here it is shown in the context of chemical reaction landscapes.A reaction free energy surface for the Claisen rearrangement of chorismate to prephenate is used as an illustration of the method's efficient *** simulations are shown to achieve flat histograms for complex multidimensional free energy *** sampling efficiency by which it produces multidimensional free energies is demonstrated on the complex puckering of a pyranose ring,that is described by a three dimensional W(θ1,θ2,θ3) potential of mean force.

关键词： free energy calculations reaction dynamics reaction surfaces multidimensional free energy surfaces

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折出莫比乌斯带极限

环球科学 2024年第13期 58-63页

作者：凯文·哈特尼特柳翔(翻译) 不详河北师范大学数学科学学院

日常生活中的折纸不仅能折出纸飞机和纸鹤,还能帮助数学家找到最特别的莫比乌斯带。在过去的两年中,数学家终于确定了儿童游戏室中常见折纸游戏的最佳纸带形状。但最近这些研究结果在数学中占据了一个相当奇怪的角落。确切地说,这些研... 详细信息

日常生活中的折纸不仅能折出纸飞机和纸鹤,还能帮助数学家找到最特别的莫比乌斯带。在过去的两年中,数学家终于确定了儿童游戏室中常见折纸游戏的最佳纸带形状。但最近这些研究结果在数学中占据了一个相当奇怪的角落。确切地说,这些研究的合作者很不寻常,其中涉及一位数学家与他妻子的折纸练习,以及一位教授教她的本科生玩折纸。

关键词：莫比乌斯带纸飞机折纸儿童游戏室合作者数学家本科生日常生活