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Science China Mathematics 2006年第12期49卷 1897-1900页

作者： cheung Wing-Sum WONG Bun Department of Mathematics University of Hong Kong Department of Mathematics University of California at Riverside

In this paper,we give certain homotopy and diffeomorphism versions as a generalization to an earlier result due to ***,Bun Wong and Stephen *** concerning a local rigidity problem of the tangent bundle over compact su... 详细信息

关键词： Chern numbers complex surfaces of general type coholomogy group local moduli local deformation space Miyaoka-Yau inequality Yau's global rigidity theorem Yau's uniformization theorem.

Gradient descent decomposition of force-field motor primitives optogenetically elicited for motor mapping of the murine lumbosacral spinal cord

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Zoological Research 2023年第3期44卷 604-619页

作者： Paola Salmas Vincent C.K cheung School of Biomedical Sciences and Gerald Choa Neuroscience InstituteThe Chinese University of Hong KongHong Kong SARChina Kunming Institute of Zoology-The Chinese University of Hong Kong(KIZ-CUHK)Joint Laboratory of Bioresources and Molecular Research of Common Diseases Hong Kong SARChina

Generating diverse motor behaviors critical for survival is a challenge that confronts the central nervous system(CNS)of all *** movement execution,the CNS performs complex calculations to control a large number of neuromusculoskeletal *** theory of modular motor control proposes that spinal interneurons are organized in discrete modules that can be linearly combined to generate a variety of behavioral *** modules have been previously represented as stimulus-evoked force fields(FFs)comprising isometric limb-endpoint forces across workspace ***,we ask whether FFs elicited by different stimulations indeed represent the most elementary units of motor control or are themselves the combination of a limited number of even more fundamental motor *** probe for potentially more elementary modules,we optogenetically stimulated the lumbosacral spinal cord of intact and spinalized Thy1-ChR2 transgenic mice(n=21),eliciting FFs from as many single stimulation loci as possible(20-70 loci per mouse)at minimally necessary *** found that the resulting varieties of FFs defied simple categorization with just a few *** used gradient descent to further decompose the FFs into their underlying basic force fields(BFFs),whose linear combination explained FF *** mice,we identified 4-5 BFFs with partially localizable but overlapping representations along the spinal *** BFFs were structured and topographically distributed in such a way that a rostral-to-caudal traveling wave of activity across the lumbosacral spinal cord may generate a swing-to-stance gait *** BFFs may represent more rudimentary submodules that can be flexibly merged to produce a library of motor modules for building different motor behaviors.

关键词： Motor mapping Optogenetics Spinal cord Motor primitives Traveling wave

Resource Allocation in Public Healthcare: A Team-DEA Model

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Journal of Systems Science & Complexity 2018年第2期31卷 463-472页

作者： LAI Kin Keung cheung Michael Tow FU Yelin Department of Management Sciences City University of Hong Kong Kowloon Hong Kong China Jockey Club School of Public Health and Primary Care Faculty of Medicine The Chinese University of Hong Kong Shatin Hong Kong China

This paper combines the theory of teams and data envelopment analysis（DEA） to design a mechanism to optimally allocate resources in public healthcare. A statutory authority and the public hospitals under its governance are interpreted as a team, the members of which seek to operate efficiently under the shared institutional constraint that public healthcare is a public good. The individual public hospital exploits DEA to maximize own-payoff, subject to the team-condition that the payoff of each other public hospital does not fall and thereby subtract from the external effects created by the public supply of healthcare. The resulting team-DEA solution, which is shown to be both an individuallyefficient and team-satisficing equilibrium and to be computable in terms of a convergent algorithm, can then be applied by the authority to determine the optimal allocation of resources in public healthcare.A case based on Chinese data is presented to illustrate the team-DEA model＇s ready operationalization and computation.

关键词： Data envelopment analysis hospital authority public goods public healthcare resourceallocation mechanism teams.

A Versatile Flow-Profile Engineering Method in the Stokes Flow Regime for Complex-Shaped Flows

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Engineering 2021年第5期7卷 655-662页

作者： Zhenyu Yang Lang Nan Ho cheung Shum Department of Mechanical Engineering The University of Hong KongHong Kong 999077China

Flow profiles are frequently engineered in microfluidic channels for enhanced mixing,reaction control,and material ***,flow profiles are engineered by inducing inertial secondary flow to redistribute the streams,which can hardly be reproduced in microfluidic environments with negligible inertial *** employed symmetric channel structures also limit the variety of achievable flow ***,each of the flow profiles specifically corresponds to a strictly defined flow condition and cannot be generalized to other flow *** address these issues,we present a systematic method to engineer the flow profile using inertialess secondary *** flow is manipulated in the Stokes regime by deploying a cascaded series of microsteps with various morphologies inside a microchannel to shape the flow *** tuning the shapes of the microsteps,arbitrary outflow profiles can be customized.A numerical profile-transformation program is developed for rapid prediction of the output profiles of arbitrary sequences of predefined *** proposed method allows the engineering of stable flow profiles,including asymmetric ones,over a wide range of flow conditions for complex microfluidic environmental prediction and design.

关键词： Microfluidics Flow profile Stokes flow Hydrodynamic focusing Flow shaping

Supramolecular Metal Complex with Ferrocene-conjugated Macrocyclic Triaza Crown Ether as Ligand and Its Electrochemical Property

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Chinese Chemical Letters 1998年第3期9卷 269-272页

作者： Yin, YG cheung, KK Wong, WT Jingzhou Teachers Coll Dept Chem Jingsha 434100 Hubei Peoples R China Univ Hong Kong Dept Chem Hong Kong Peoples R China

A tetranuclear complex [Co(III)(2)(L)(2)(AcO)(2)(OH)](AcO)(2I). 4H(2)O (L = N-ferrocenylmethyl-1,4,7-triaza-cyclononane) was prepared from ligand L . HI and its crystal structure was determined. The crystal exists in P2(1)(/)a space group and its cell parameters are a = 14.285(3)Angstrom, b = 19.888(3)Angstrom, c = 19.133(3)Angstrom; beta = 109.12(2)degrees; V = 5135.8 Angstrom(3); Z = 4. Electrochemical investigation reveals that the oxidation potential of ferrocenyl group in 1 has a 0.11V-positive-shift from that of the ferrocenyl group in ***.

关键词： supermolecule ferrocene host-guest electronic interaction

One-Pot Synthesis of Substituted Cyclohexanes from Condensation of Aldehyde and Methylketone

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Chinese Chemical Letters 1998年第4期9卷 329-332页

作者： Yin, YG cheung, KK Wong, WT Jingzhou Teachers Coll Dept Chem Jingzhou 434100 Hubei Peoples R China Univ Hong Kong Dept Chem Hong Kong Hong Kong

Three asymmetrically substituted cyclohexanes were prepared from one-pot reactions of aldehydes and methylketones, and the products were characterized by single crystal structure analysis, NMR spectroscopy and microan... 详细信息

关键词： Michael reaction intermolecular condensation substituted cyclohexane

Lu Xun＇s View of the Awakening of the Chinese People--Was There Really an ＂Epistemological Break＂？

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Frontiers of Literary Studies in China-Selected Publications from Chinese Universities 2012年第3期6卷 410-425页

作者： Chiu-yee cheung Division of Chinese School of Humanities and Social Science Nanyang Technological University Singapore 639798 Singapore

It has been argued that, starting in the late 1920s, Lu Xun＇s intellectual development underwent a significant transformation constituting what the French Marxist philosopher Louis Althusser has termed an ＂epistemological break.＂ Some of the explicitly more positive comments about the masses that Lu Xun made in his later years have been used to demonstrate this point. However, the existence of such a ＂break＂ is still debatable, and a detailed examination of Lu Xun＇s apparently optimistic comments reveals that Lu Xun possessed a more sophisticated understanding of the masses and the Chinese people. His understanding was informed by the concept of ＂national character.＂ This paper attempts to demonstrate the consistency of Lu Xun＇s view of the masses and the Chinese people and to resolve an apparent self-contradiction in Lu Xun＇s arguments.

关键词： Lu Xun Chinese "national character" epistemological break

Simple Metrics for Representing East Asian Winter Monsoon Variability:Urals Blocking and Western Pacific Teleconnection Patterns

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Advances in Atmospheric Sciences 2016年第6期33卷 695-705页

作者： Hoffman H.N.cheung Wen ZHOU Guy Carpenter Asia-Pacific Climate Impact Centre School of Energy and EnvironmentCity University of Hong KongHong Kong SAR City University of Hong Kong Shenzhen Research Institute Shenzhen 518057

Instead of conventional East Asian winter monsoon indices （EAWMIs）, we simply use two large-scale teleconnection patterns to represent long-term variations in the EAWM. First, the Urals blocking pattern index （UBI） is closely related to cold air advection from the high latitudes towards western Siberia, such that it shows an implicit linkage with the Siberian high intensity and the surface air temperature （SAT） variations north of 40°N in the EAWM region. Second, the well-known western Pacific teleconnection index （WPI） is connected with the meridional displacement of the East Asian jet stream and the East Asian trough. This is strongly related to the SAT variations in the coastal area south of 40°N in the EAWM region. The temperature variation in the EAWM region is also represented by the two dominant temperature modes, which are called the northern temperature mode （NTM） and the southern temperature mode （STM）. Compared to 19 existing EAWMIs and other well-known teleconnection patterns, the UBI shows the strongest correlation with the NTM, while the WPI shows an equally strong correlation with the STM as four EAWMIs. The UBI-NTM and WPI-STM relationships are robust when the correlation analysis is repeated by （1） the 31-year running correlation and （2） the 8-year high-pass and low-pass filter. Hence, these results are useful for analyzing the large-scale teleconnections of the EAWM and for evaluating this issue in climate models. Int particular, more studies should focus on the teleconnection patterns over extratropical Eurasia.

关键词： East Asian winter monsoon Urals blocking high western Pacific teleconnection pattern teleconnection

A novel adjustable multiple cross-hexagonal search algorithm for fast block motion estimation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1304-1310页

作者： XIE Chun-lai cheung Chun-ho LIU Wei-zhong Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China Hong Kong Institute of Technology Hong Kong China

In this paper,we propose a novel adjustable multiple cross-hexagonal search(AMCHS) algorithm for fast block motion estimation. It employs adjustable multiple cross search patterns(AMCSP) in the first step and then uses half-way-skip and half-way-stop technique to determine whether to employ two hexagonal search patterns(HSPs) subsequently. The AMCSP can be used to find small motion vectors efficiently while the HSPs can be used to find large ones accurately to ensure prediction quality. Simulation results showed that our proposed AMCHS achieves faster search speed,and provides better distortion performance than other popular fast search algorithms,such as CDS and CDHS.

关键词： Motion estimation Fast search algorithm Adjustable search patterns Threshold strategy Hexagonal search pattern

DYNAMIC MODELLING OF BAR-GEAR MIXED MULTIBODY SYSTEMS USING A SPECIFIC FINITE ELEMENT METHOD

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Chinese Journal of Mechanical Engineering 1999年第2期12卷 12-18页

作者： Wang, Yong cheung, Hongman Edmund Zhang, Wenjun City Univ of Hong Kong Hong Kong Hong Kong

A new dynamic model for mixed, flexible bar and gear multibody systems is developed based on a specific finite element method, and a new gear element is proposed. The gear element can take into account the time variant stiffness, the gear errors and mass unbalance. The model for geared multibody systems can couple the gear meshing and the flexibility of all contained components. The kinematic and dynamic analyses of the geared multibody systems are expounded and illustrated on an example composed of three gears, two bars and one slider.

关键词： Gear Finite element Multibody system Simulation Dynamics