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NONLINEAR FREE SURFACE ACTION WITH AN ARRAY OF VERTICAL CYLINDERS

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Acta Mechanica Sinica 2004年第3期20卷 247-262页

作者： HUANG j.B. Department of Engineering Science University of OxfordUK

Nonlinear diffraction of regular waves by an array of bottom-seated circular cylindersis investigated in frequency domain,based on a Stokes expansion approach.A complete semi-analyticalsolution is developed which allows an efficient evaluation of the second-order potentials in the entirefluid domain,and the wave forces on the *** are derived for the second-orderpotential in the vicinity of individual *** expressions have a simple form,thus providingan effective means for investigating the wave enhancement due to nonlinear interactions with *** on the present method,the wave run-up and free-surface elevations around an arrayof two,three and four cylinders are investigated numerically.

关键词： nonlinear wave diffraction water waves frequency analysis semi-analytical method

High-temperature mechanical properties of aluminium alloys reinforced with titanium diboride (TiB_2) particles

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Rare Metals 2011年第2期30卷 200-205页

作者： j.Ooro Ingeniería y Ciencia de los Materiales ETSI IndustrialesUniversidad Politécnica de Madridc/José Gutiérrez Abascal2.28006 MadridSpain

The physical and mechanical properties of metal matrix composites were improved by the addition of reinforcements. The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys （6061 and 7015） at high temperatures were studied. Titanium diboride （TiB2） particles were used as the reinforcement. All the composites were produced by hot extrusion. The tensile properties and fracture characteristics of these materials were investigated at room temperature and at high temperatures to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy. TiB2 particles provide high stability of the alumin- ium alloys （6061 and 7015） in the fabrication process. An improvement in the mechanical behaviour was achieved by adding TiB2 particles as reinforcement in both the aluminium alloys. Adding TiB2 particles reduces the ductility of the aluminium alloys but does not change the microscopic mode of failure, and the fracture surface exhibits a ductile appearance with dimples formed by coalescence.

关键词： metal-matrix composites aluminium high-temperature properties titanium diboride

Development process for a higher capacity Propsetter~ system

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International journal of Mining Science and Technology 2018年第1期28卷 121-126页

作者： Christopher j.Brown Product Development-Strata Worldwide LLC

As longwall tailgate support technologies continue to be developed and improved, strata worldwide has worked to design and manufacture a revised Propsetter to provide additional support capacity and enable applications at greater mine *** support is targeted for tailgate applications, however, it can also be utilized for roof support in various types of mining *** paper describes the design changes for enhancing the support capacity of the Propsetter to more closely align its performance with other support technologies currently being employed in longwall *** changes to each design aspect of the Propsetter was key to successfully improving the roof support's load capacity while maintaining controlled *** the load capacity would allow a mine to improve support efficiency with a smaller, less intrusive support compared to support alternatives and reduce the cost per foot of supported *** target support capacity was 711–890 k N at 50 mm of deformation to more closely match the performance of competing tailgate supports such as the 610 mm-diameter CAN~.To achieve this goal, changes were made to all design aspects of the Propsetter: diameter, wedge cut depth and angle, pod size, and confinement *** results from the NIOSH Mine Roof Simulator verified that these design changes were successful in increasing the capacity of the Propsetter to the 711–890 k N range at fifty mms of deformation.

关键词： Propsetter Can Longwall mining Tailgate roof support Controlled deformation

Heat Transfer Optimization for Air-Mist Cooling between a Stack of Parallel Plates

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journal of Thermal Science 2010年第3期19卷 253-260页

作者： Roy j.Issa Mechanical Engineering Division Department of Engineering and Computer Science West Texas A&M University CanyonTexas 79016USA

A theoretical model is developed to predict the upper limit heat transfer between a stack of parallel plates subject to multiphase cooling by air-mist *** model predicts the optimal separation distance between the plates based on the development of the boundary layers for small and large separation distances,and for dilute mist *** results show the optimal separation distance to be strongly dependent on the liquid-to-air mass flow rate loading ratio,and reach a limit for a critical *** these dilute spray conditions,complete evaporation of the droplets takes *** results also show the optimal separation distance decreases with the increase in the mist flow *** proposed theoretical model shall lead to a better understanding of the design of fins spacing in heat exchangers where multiphase spray cooling is used.

关键词： Air-mist Multiphase Heat transfer Liquid-to-air loading

Plasma-catalysis: Is it just a question of scale?

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Frontiers of Chemical Science and Engineering 2019年第2期13卷 264-273页

作者： j.Christopher Whitehead School of Chemistry The University of ManchesterManchester M13 9PLUK

The issues of describing and understanding the changes in performance that result when a catalyst is placed into plasma are discussed. The different chemical and physical interactions that result and how their combination might produce beneficial results for the plasma-catalytic processing of different gas streams are outlined with particular emphasis being placed on the different range of spatial and temporal scales that must be considered both in experiment and modelling. The focus is on non-thermal plasma where the lack of thermal equilibrium creates a range of temperature scales that must be considered. This contributes in part to a wide range of inhomogeneity in different properties such as species concentrations and electric fields that must be determined experimentally by in situ methods and be incorporated into modelling. It is concluded that plasmacatalysis is best regarded as conventional catalysis perturbed by the presence of a discharge, which modifies its operating conditions, properties and outcomes often in a very localised way. The sometimes used description "plasma-activated catalysis" is an apt one.

关键词： plasma catalysis plasma-activated catalysis non-thermal plasma CO2 conversion

Combining Aluminum Heat Treat with Hot Isostatic Pressing: A Comparison of Structure, Properties, and Processing Routes for a Cast AI-Si-Mg Alloy

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材料热处理学报 2004年第5期25卷 546-551页

作者： Stephen j. Mashl Body cote HIP Inc. Andover Massachusetts USA

Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.

关键词： Al-Si-Mg合金热处理热等静压缩 HIP 机械性质疲劳寿命

Hybrid silicon modulators

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Chinese Optics Letters 2009年第4期7卷 280-285页

作者： j.E.Bowers Department of Electrical and Computer Engineering University of California Santa Barbara

A number of active elements have been demonstrated using the hybrid silicon evanescent platform, including lasers, amplifiers, and detectors. In this letter, two types of hybrid silicon modulators, flflfilling the building blocks in optical communication on this platform, are presented. A hybrid silicon electroabsorp- tion modulator, suitable for high speed interconnects, with 10-dB extinction ratio at -5 V and 16-GHz modulation bandwidth is demonstrated. In addition, a hybrid silicon Mach-Zehnder modulator utilizing carrier depletion in multiple quantum wells is proved with 2 *** voltage-length product, 150-nm optical bandwidth, and a large signal modulation up to 10 Gb/s.

关键词： Bandwidth Electroabsorption modulators Modulation Modulators Optical communication Quantum well lasers Semiconducting indium compounds Semiconductor quantum wells Silicon Silicon detectors

ON COMPUTING ZEROS OF A BIVARIATE BERNSTEIN POLYNOMIAL

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journal of Computational Mathematics 1996年第3期14卷 237-248页

作者： Chen, FL Kozak, j UNIV SCI & TECHNOL CHINA DEPT MATHHEFEIPEOPLES R CHINA UNIV LjUBLjANA DEPT MATHLJUBLJANA 1000SLOVENIA

In this paper, the problem of computing zeros of a general degree bivariate Bernstein polynomial is considered. An efficient and robust algorithm is presented that takes into full account particular properties of the function considered. The algorithm works for rectangular as well as triangular domains. The outlined procedure can also be applied for the computation of the intersection of a Bezier patch and a plane as well as in the determination of an algebraic curve restricted to a compact domain. In particular, singular points of the algebraic curve are reliably detected.

关键词： Figure Design ON COMPUTING ZEROS OF A BIVARIATE BERNSTEIN POLYNOMIAL

Formalisms to Support the Definition of Processes

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journal of Computer Science & Technology 2009年第2期24卷 198-211页

作者： Leon j. Osterweil Department of Computer Science University of Massachusetts Amherst

This paper emphasizes the importance of defining processes rigorously, completely, clearly, and in detail in order to support the complex projects that are essential to the modern world. The paper argues that such process definitions provide needed structure and context for the development of effective software systems. The centrality of process is argued by enumerating seven key ways in which processes and their definitions are expected to provide important benefits to society. The paper provides an example of a process formalism that makes good progress towards the difficult goal of being simultaneously rigorous, detailed, broad, and clear. Early experience suggests that these four key characteristics of this formalism do indeed seem to help it to support meeting the seven key benefits sought from process definitions. Additional research is suggested in order to gain more insights into needs in the area of process definition formalisms.

关键词： processes process definition process language