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Thermoelastic properties of sandwich materials with pin-reinforced foam cores

Science China(Technological Sciences) 2008年第12期51卷 2059-2074页

作者： LU TianJian1,LIU Tao2,3 & DENG ZiChen2,4 1 MOE Key Laboratory of Strength and Vibration,School of Aerospace,Xi’an Jiaotong university,Xi’an 710049,China 2 department of engineering Mechanics,Northwestern Polytechnical university,Xi’an 710072,China 3 department of engineering,university of cambridge,cambridge cb2.1pz,uk 4 State Key Laboratory of Structural Analysis of Industrial Equipment,Dalian university of Technology,Dalian 116024,China MOE Key Laboratory of Strength and Vibration School of Aerospace Xi’an Jiaotong University Xi’an 710049 China department of engineering Mechanics Northwestern Polytechnical University Xi’an 710072 China department of engineering University of Cambridge Cambridge CB2 1PZ UK State Key Laboratory of Structural Analysis of Industrial Equipment Dalian University of Technology Dalian 116024 China

Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins(trusses) into a foam matrix to create a truss-like network reinforced foam *** loading,the pins deform predominantly by local stretching whilst the deformation of foam is governed by local *** paper presents a theoretical study on the thermoelasticity of pin-reinforced foam sandwich *** calculate the effective thermoelastic properties of pin-reinforced foam cores,the energy-based homogenization approach is employed to develop a micromechanics-based model,calibrated by the existing experimental *** is found that the stiffness of the sandwich core is mainly governed by pin reinforcements:the foam matrix contributes little to sandwich *** with traditional foam cores without pin reinforcements,the changes in inplane thermal expansion coefficients are not vigorous as a result of pin reinforcements,while the through-thickness thermal expansion coefficient changes *** is also demonstrated that it is possible to design materials with zero or negative thermal expansion coefficients under such a context.

关键词： sandwich panel pin reinforcement analytical solutions homogenization thermoelasticity thermal expansion

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Truncation error calculation based on Richardson extrapolation for variable-step collaborative simulation

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Science China(Information Sciences) 2011年第6期54卷 1238-1250页

作者： ZHANG HeMing 1 , LIANG SiLu 2 , SONG ShiJi 1 & WANG HongWei 3 1 department of Automation, TNList, Tsinghua university, Beijing 100084, China 2 Computer and Information Management Center, Tsinghua university Beijing 100084, China 3 engineering Design Centre, engineering department, cambridge university, cambridge cb2.1pz, uk 1. department of Automation TNList Tsinghua University Beijing 100084 China2. Computer and Information Management Center Tsinghua University Beijing 100084 China3. Engineering Design Centre Engineering Department Cambridge University Cambridge CB2 1PZ UK

Collaborative simulation is an effective approach to performing simulation analysis for complex systems by integrating models developed for different engineering disciplines. Collaborative simulation issues include the modeling of coupled multidisciplinary systems, and the simulation running time integration of these models that are solved parallelly. Estimation of the local truncation error of coupling models is the key to solve multidisciplinary collaborative simulation problem, which is actually used to restrict the simulation step. This paper presents a variable-step method based on Richardson extrapolation for calculating the local truncation error to solve collaborative simulation problem of multidisciplinary coupling models. Formulas for estimating the local truncation error are derived through theoretical analysis by using integration methods and interpolation technologies, respectively. The simulation experiments are illustrated to validate the accuracy and efficiency of proposed collaborative simulation algorithm in comparison with the usual combinative algorithm.

关键词： multidisciplinary systems collaborative simulation variable-step algorithm error estimation

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A flexible framework for HMM based noise robust speech recognition using generalized parametric space polynomial regression

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Science China(Information Sciences) 2011年第12期54卷 2501-2511页

作者： CHENG Ning 1 , LIU XunYing 1,2 & WANG Lan 1 1 Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences/The Chinese university of Hong Kong, Hong Kong, China 2.cambridge university engineering department, cambridge cb2.1pz, uk 1. Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences/The Chinese University of Hong Kong Hong Kong China2. Cambridge University Engineering Department Cambridge CB2 1PZ UK

Handling variable, non-stationary ambient noise is a challenging task for automatic speech recognition (ASR) systems. To address this issue, multi-style, noise condition independent (CI) model training using speech data collected in diverse noise environments, or uncertainty decoding techniques can be used. An alternative approach is to explicitly approximate the continuous trajectory of Gaussian component mean and variance parameters against the varying noise level, for example, using variable parameter hidden Markov model (VP-HMM). This paper investigates a more generalized form of variable parameter HMMs (GVP-HMM). In addition to Gaussian component means and variances, it can also provide a more compact trajectory modeling for tied linear transformations. An alternative noise condition dependent (CD) training algorithm is also proposed to handle the bias to training noise condition distribution. Consistent error rate gains were obtained over conventional VP-HMM mean and variance only trajectory modeling on a media vocabulary Mandarin Chinese in-car navigation command recognition task.

关键词： non-stationary noise generalized variable parameter HMM noise robust speech recognition

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Exploration and Understanding of Manufacturing Networks:From Manufacturing Centres Towards Global Inter-firm Relationships

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厦门大学学报（自然科学版） 2002年第S1期41卷 254-256页

作者： Yongjiang Shi (engineering department, The university of cambridge, uk)

The boundaries of manufacturing system have been ex te nded from factory to the international manufacturing network, supply network, va lue network and virtual network in recent decades, driven by intensified competi tion, fragmented market, globalised collaboration, and advanced technology. However, as the manufacturing system evolves into more and more complicated net work relationship, the fundamental concepts of manufacturing strategy focusing o n a product family and bridging its market, competition and factory system have rarely been adapted to face new challenges from extended system, although the st rategy formation processes are widely discussed from both perspectives in terms of top-down and bottom-up. Coming into the new economy, as manufacturing industry and system have changed their role in both company and society, manufac turing, especially physical fabrications and assembly, has become less critical than ten years ago, and the compatible manufacturing strategy has been also chal lenged by the new rules based on knowledge development and by the new business m odel based on value creation. Manufacturing strategy has to find a position and mechanism contributing itself to the corporate strategy and competitive advanta ge. This paper seeks to answer the question what networked manufacturing systems can imply to the manufacturing strategy, by clarifying some key challenges to the c lassical manufacturing strategy theory, especially from networked manufacturing system and value-based manufacturing strategy perspectives. The paper is based on some preliminary case observations in several multinationa l corporations in aerospace, automotive, engineering and electronics industries. Original objectives are targeted on an evolutionary process of manufacturing system from factory-based system towards globally collaborated inter-firm netw ork, seeking to explain why manufacturing companies evolve into more and more un controllable relationship. The preliminary fi

关键词： new manufacturing strategy supply chain virtu al enterprises value constellation

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Developing Chinese Collaborative Manufacturing:From the Perspective of Western Manufacturing System Evolution

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厦门大学学报（自然科学版） 2002年第S1期41卷 172-173页

作者： Yilei Liu, Yongjiang Shi (engineering department, The university of cambridge, uk)

Chinese manufacturing companies are facing intensif ie d challenges from the world after joining the world trade organisation (WTO). I t is especially critical when China is currently trying to achieve its industria lisation. To identify gaps between Chinese manufacturers and world class player s can actually help Chinese companies understand real challenges and opportuniti es for improvement. Various types of manufacturing technologies and systems have been emerging drama tically since information, manu...

关键词： manufacturing system collaborative manufacturing Contemporary Integrated Manufacturing (CIM)

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Preliminary Study on Aluminium-based Nanophase Composites Al_(88)Ni_(10)Y_2 and Al_(88)Ni_8Y_4

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Journal of Materials Science & Technology 1996年第1期12卷 1-6页

作者： Z. C.Zhong and A.L. Greer(Dept. of Materials Science & Metallurgy, university of cambridge, Pembroke Street, cambridge cb2 3QZ, uk) Dept. of Materials Science and Metallurgy University of Cambridge Pembroke Street Cambridge CB2 3QZ United Kingdom

A new kind of aluminium-based alloy part amorphous/part crystalline, can be produced directlyby rapid quenching of the liquid. These materials have a novel structure of nanometer-sizedcrystals in an amorphous matrix and quite remarkable mechanical properties. The materialscan be considered to be nanophase composites. In this work Al88Ni10Y2 and Al88Ni8Y4 (atpct) nanophase composites consisting of a nanoscale dispersion of fcc-Al crystallites uniformlydispersed in an amorphous matrix, have been produced by melt-spinning. They have much highermicrohardness HV than fully amorphous alloys with the same composition. while retaining goodbending ductility The volume fraction, crystallite size and distribution of the fcc-Al phase havebeen estimated by DSC. X-ray diffraction and TEM. lt is found that the microstructure andproperties of the nanophase composites are very sensitive to the composition and the quenchingconditions. lncreasing the Y contedt and decreasing the Ni content at a given Al content givesmuch smaller dispersed nanophase aluminium crystallites. The volume fraction and crystallitesize of the fcc-Al phase increase with a decrease of wheel speed (quenching rate). The effectsof Y and Ni contents on the ease of formaticn of the nanophase composites are discussed. Theorigins of the novel mechanical properties are also considered.

关键词： Ni8Y4 Figure Y2 and Al

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A MAGNUS EXPANSION FOR THE EQUATION Y'= AY - YB

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Journal of Computational Mathematics 2001年第1期19卷 15-26页

作者： Arieh Iserles (department of Applied Mathematics and Theoretical Physics, university of cambridge, Silver Street, cambridge cb3 9EW, England) university of cambridge 英国 CB3 9EW

The subject matter of this paper is the representation of the solution of the linear differential equation Y = AY - YB, Y(0) = Yo, in the form y(t) = eΩ(t)Y0 and the representation of the function n as a generalization of the classical Magnus expansion. An immediate application is a new recursive algorithm for the deriVation of the Baker- Campbell-Hausdorff formula and its symmetric generalization.

关键词： Geometric integration Magnus expansions B aher- Campbell- Hausdorff formula.

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Lessons from Rotor 37

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Journal of Thermal Science 1997年第1期6卷 1-13页

作者： J.D. Denton(Whittle Laboratory cambridge university engineering Dept., cambridge, England) Whittle Laboratory Cambridge University Engineering Dept. Cambridge England

NASA rotor 37 was used as a ’blind’ test case for turbomachinery CFD by the Turbimachinery Com-mittee of the IGTI. The rotor is a transonic compressor with a tip speed of 454 m/s (15OO ft/s) anda relatively high pressure ratio of 2.1. It was tested in isolation with a circumferentially uniform inletflow so that the flow through it should be steady apart from any effects of passage to passage geometry variation and mechanical vibration. As such it represents the simplest possible type of test forthree-dimensional turbomachinery flow solvers. However, the rotor still presents a real challenge to3D viscous flow solvers because the shock wave-boundary layer interaction is strong and the effects ofviscosity are dominant in determining the flow deviation and hence the pressure ratio. Eleven ’blind’solutions were submitted and in addition a ’non-blind’ solution was used to prepare for the exercise-This paper reviews the fiow in the test case and the comparisons of the CFD solutions with the testdata. Lessons for both the Flow Physics in transonic has and for the application of CFD to suchmachines are pointed out.

关键词： transonic compressor rotor shock wave-boundary layer interation CFD ‘blind’ solutions

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Recent Advance in the Electrochemical Detection of Sulphide and Sulphhydryl Species

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Chemical Research in Chinese Universities 2002年第2期18卷 161-168页

作者： Nathan S. Lawrence 1, Timothy G. J. Jones 2, Richard G. Compton 1 and Li Jiang 2.1. Physical and Theoretical Chemistry Laboratory, university of Oxford, Oxford, OX1 3QZ, uk 2. Schlumberger cambridge Research, High Cross, Madingley Road, cambridge, Univ Oxford Phys & Theoret Chem Lab Oxford OX1 3QZ England Schlumberger cambridge Res Ltd Cambridge CB3 0EL England

This article aims at providing a critical review of some most recent developments in the electrochemical detection and measurement of hydrogen sulphide and the related species, which are of great significance to a variety of industries and in environmental moitoring. The molecular recognition processes are initiated by using either an organic precursor or a catalytic complex, leading to extensive ranges of detection. A series of advanced chemical and simulation techniques are used to probe the mechanistic details of the analytical chemistry involved.

关键词： Advance, Electrochemical detection, Sulphide Sulphhydryl

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THE EFFECT OF LESSER HIMALAYAN CALC-SILICATES ON THE ^(87)Sr/^(86)Sr OF THE BHOTE KOSI RIVER OF NEPAL—IMPLICATIONS FOR HIMALAYAN WEATHERING, THE MARINE ^(87)Sr/^(86)Sr RECORD AND GLOBAL CLIMATE

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地学前缘 2000年第S1期7卷 396-397页

作者： Lee Oliver 1,Nigel Harris 1, Nancy Dise 1,Mike Bickle 2[WT5,5”BX](1 department of Earth Sciences, Open university, Milton Keynes MK7 6AA, uk 2 department of Earth Sciences, cambridge university, cambridge cb2 3EQ, uk)

During the last 40Ma the marine 87 Sr/ 86 Sr record shows a rapid rise (from 0 7078 to 0 7092) [1] , a trend which has been linked to the Himalayan Orogeny [2] . Indeed, many Himalayan rivers, principally those of the Ganges\|Brahmaputra system, display high 87 Sr/ 86 Sr relative to [Sr] [3] . Theories concerning the cause of this radiogenic Sr enrichment are diverse, but our results suggest that Lesser Himalayan carbonate\|rich lithologies play a vital role [4,5] .The Bhote Kosi originates in Tibet at ca.5km elevation from Tibetan Sedimentary Series (TSS) bedrock, before traversing the High Himalayan Crystalline Series (HHCS) and Lesser Himalaya (LH) of eastern Nepal, joining the Indrawati (at ca.0 6km elevation) to form the Sun Kosi, part of the Ganges system. Carbonates, calc\|silicates and silicates have been identified from the TSS, HHCS and LH, and the Bhote Kosi provides an opportunity to study the influence of these upon fluvial chemistry. Interest is focused on the cause of a rapid rise in riverine Sr\|isotope ratios immediately downstream of the Main Central Thrust (MCT) and the role of carbonate\|rich lithologies exposed in this section. Similar lithologies are lacking in the catchment of a second Nepalese river system, the Lantang Khola—Trisuli, sampled during the same period, and used as a baseline indicator for the effect of LH carbonates on the dissolved load of the Bhote Kosi.

关键词： weathering strontium isotopes Himalayan rivers carbonates

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