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Cooling pathways for deep Australian longwall coal mines of the future

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International Journal of mining Science and Technology 2018年第6期28卷 865-875页

作者： b.belle m.biffi Anglo American Coal QueenslandAustralia Department of mining Engineering UNSWSydneyNSW 2052Australia Anglo American Operations(Pty)Ltd. Johannesburg 2001South Africa

Cooling of coal mines in the bowen basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures over 50 °C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures(WbT) to below 27 °C at which point the risks of heat stroke or other heat related issues are manageable. The capacities of these systems are in the range of 6–10 mW refrigeration power. The relationship between high working temperature environment and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long term cooling pathways to effectively manage the thermal hazards. Thermodynamic modeling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarizes the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the bowen basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers(bACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants,are discussed in this paper. Finally, the comparison of ‘rental' versus ‘ownership' of cooling plants is analysed as part of long-term cooling strategies.

关键词： Cooling Chilled water Underground Positional efficiency Thermal hazard

A review of light amplification by stimulated emission of radiation in oil and gas well drilling

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mining Science and Technology 2010年第5期20卷 752-757页

作者： OLALEYE b m Department of mining Engineering Federal University of Technology

The prospect of employing Light Amplification by Stimulated Emission of Radiation(LASER) for well drilling in oil and gas industry was *** this work,the experimental works carried out on various oil well drilling operations was *** results show that,LASER or LASER-aided oil and gas well drilling has many potential advantages over conventional rotary drilling,including high penetration rate,reduction or elimination of tripping,casing,bit costs,enhanced well control,as well as perforating and side-tracking *** investigation also reveals that modern infrared LASERs have a higher rate of rock cuttings removal than that of conventional rotary drilling and flame-jet *** also reveals that LASER can destroy rock without damaging formation permeability but rather,it enhances or improves permeability and that permeability and porosity increases in all rock *** paper has therefore provided more knowledge on the potential value to drilling operations and techniques using LASER.

关键词： LASER oil gas well drilling simulation specific energy spallation

Sample geometric mean versus sample median in closed form framework of seismic reliability evaluation: a case study comparison

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 187-201页

作者： m.Abyani b.Asgarian m.Zarrin Faculty of Civil Engineering K.N.Toosi University of Technology

Earthquake engineers have made a lot of efforts to derive a comprehensive set of closed form expressions for performance evaluation of frames, which are already presented in guidelines such as SAC/FEmA. These analytical expressions have been developed to estimate the annual probability of exceeding a limit state. In the process of such seismic assessments, some essential assumptions are adopted to simplify the process. One of these fundamental assumptions declares that drift demand at any seismic intensity level follows a lognormal distribution around its median. To investigate the validity of this assumption, this paper describes a case study of the types of errors that could be produced by using the sample median as the central tendency. based on the maximum Likelihood Estimation method as well as other statistical evidence, this paper proposes the use of the sample geometric mean instead of the sample median for the central tendency. Further, the results of seismic reliability evaluations of 4 sample frames are compared based on utilizing both the geometric mean and the sample median. In this process, both first and second order power law fits of the hazard curve are implemented to compare the effects of hazard estimation and the selection of the central tendency on the final results. It is observed in the application example that the sample geometric mean could lead to more accurate results.

关键词： seismic reliability closed-form expression SAC/FEmA limit state median geometric mean

Warm Deformation of Low Carbon Steel Using Forward Extrusion-Equal Channel Angular Pressing Technique

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Journal of Iron and Steel Research International 2013年第2期20卷 68-71页

作者： b Eghbali m Shaban Department of materials Science Engineering Sahand University of Technology

A combination of extrusion and equal channel angular pressing （ECAP） was used to deform a plain low carbon steel. This process consists of two successive deformations by extrusion and ECAP in a single die （Ex-ECAP）. Cylindrical samples were heated to predefined temperatures （650 and 850 ℃） and then pressed through a die channel with crosshead speed of 10 mm/s. microstructure and resultant mechanical properties of processed material were studied. The results showed that pressing temperature has a significant effect on the resultant microstructure. While at 650 ℃, the cold worked structure with elongated ferrite grains were obtained, and at 850 ℃ the microstructure consisted of elongated ferrite grains and very fine grains at their boundaries as a consequence of continuous dynamic recrystallization （CDRX） of ferrite phase. Also at 850 ℃, a particular microstructure consisted of cold worked ferrite and static recrystallized grains on shear bands was obtained.

关键词： extrusion equal channel angular pressing low carbon steel

Existence of traveling wave solutions for a nonlinear dissipative-dispersive equation

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Applied mathematics and mechanics(English Edition) 2009年第4期30卷 513-516页

作者： m.b.A.mansour mathematics Department Faculty of Science at Qena South Valley University

In this paper, we consider a dissipative-dispersive nonlinear equation appliable to many physical phenomena. Using the geometric singular perturbation method based on the theory of dynamical systems, we investigate the existence of its traveling wave solutions with the dissipative terms having sufficiently small coefficients. The results show that the traveling waves exist on a two-dimensional slow manifold in a three-dimensional system of ordinary differential equations （ODEs）. Then, we use the melnikov method to establish the existence of a homoclinic orbit in this manifold corresponding to a solitary wave solution of the equation. Furthermore, we present some numerical computations to show the approximations of such wave orbits.

关键词： dissipative-dispersive equation singular perturbations traveling waves

Uniform Query Framework for Relational and NoSQL Databases

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Computer modeling in Engineering & Sciences 2017年第2期113卷 171-181页

作者： J.b.Karanjekar m.b.Chandak Shri Ramdeobaba College of Engineering and management NagpurIndia and Izel Technologies Pvt Ltd.PuneIndia Shri Ramdeobaba College of Engineering and management NagpurIndia

As the data managed by applications has evolved over the years with the arrival of Web 2.0,a large number of new databases have been developed to manage various types of *** the traditional relational databases continue to exist,NoSQL databases which are document oriented or key-value stores or columnar continue to evolve and are embraced very rapidly across the *** is not just the type of data handled by these databases that is different but also the query language they use is also *** paper talks about a uniform query framework that can be used for traditional relational databases and NoSQL *** query framework can also perform joins,aggregates,filter on data from various data sources in a single query.

关键词： NoSQL RDbmS data tetrieval inter-database joins SQL Cassandra mongoDb Calcite mySQL

Theoretical study of differential cross sections for the ionization of helium by fast proton impact

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Chinese Physics b 2024年第11期33卷 255-264页

作者： m mondal b mandal T mistry D Jana m Purkait Department of Physics Ramakrishna Mission Residential CollegeNarendrapurKolkata-700103India

We present the angular distribution of the ejected electron for single ionization of He by fast proton impact.A fourbody formalism of the three-Coulomb wave is applied to calculate the triple differential cross sections at several impact energies in the scattering,perpendicular and azimuthal ***,the three-body formalism of three-Coulomb,two-Coulomb and first born approximation models has also been used to study the many-body effect on electron emission and the validity of the *** the three-Coulomb wave model,the final state wave function incorporates distortion due to the three-body mutual Coulombic *** this formalism,we use an uncorrelated and correlated born initial state,which consists of a plane wave for the incoming projectile times a two-electron bound state wavefunction of the helium atom representing the 1s2(1S)***,in the case of the three-body formalism,the initial state wavefunction consists of a long-range Coulomb distortion for the incoming projectile and one active electron of the He atom described by the Roothaan–Hartree–Fock *** structure with a single or two peaks with unequal intensity is observed in the angular distributions of the triple differential cross sections for the different kinematic *** addition,the influence of static electron correlations is investigated using different bound state wavefunctions for the ground state of the He *** the four-body formalism,the present computations are very fast by reducing a nine-dimensional integral to a two-dimensional real *** the simplicity and speed of the proposed quadrature,the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other theories.

关键词： ionization cross sections collision atoms ions

Incipient motion of gravel in a bottomless arch culvert

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International Journal of Sediment Research 2011年第1期26卷 15-26页

作者： b.m.CROOKSTON b.P.m.TULLIS Utah State University 8200 Old Main HillLoganUT 84322

Incipient motion was investigated for four gravel substrate materials in a bottomless arch culvert and a rectangular *** methods for calculating Shields parameter at incipient motion（θc） based upon local flow parameters were *** incipient motion region for bottomless arch culverts in fully turbulent flow was defined with two bounding curves on Shields *** variation ofθcas a function of relative roughness was ***,a method that utilizes measured flow velocities to determine stable substrate particle diameters for bottomless arched culverts is presented as an alternative to the Shields diagram.

关键词： Incipient motion bottomless arch culvert Shields parameter Flow rate Experiment

Critical Finite Size Scaling Relation of the Order-Parameter Probability Distribution for the Three-Dimensional Ising model on the Creutz Cellular Automaton

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Chinese Physics Letters 2006年第10期23卷 2670-2673页

作者： b.Kutlu m.Civi Department of Physics Gazi University 06500 Ankara Turkey

We study the order parameter probability distribution at the critical point for the three-dimensional spin-1/2 and spin-1 Ising models on the simple cubic lattice under periodic boundary conditions. The finite size scaling relation for the order parameter probability distribution is tested and verified numerically by microcanonical Creutz cellular automata simulations. The state critical exponent δ, which characterizes the far tail regime of the scaling order parameter probability distribution, is estimated for three-dimensional Ising models using the cellular automaton simulations at the critical temperature. The results are in good agreement with the monte Carlo calculations.

关键词： bLUmE-CAPEL mODEL mONTE-CARLO RENORmALIZATION-GROUP TRICRITICAL bEHAVIOR FREE-ENERGY mAGNETIZATION UNIVERSALITY SImULATION DImENSIONS EXPONENTS