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991.
Matthew K.O. Lee Na Shi Christy M.K. Cheung Kai H. Lim Choon Ling SiaAuthor vitae 《Information & Management》2011,48(6):185-191
While much of the current literature tends to focus on the direct effect of social influence on consumer online shopping behavior, our study drew heavily on social influence theory and argued for an alternative theory focusing on the moderating role of social influence. In particular, we explored how positive messages in online discussion forums may affect consumers’ decisions to shop online. We used a laboratory experiment in which the treatment group was required to read positive messages about online shopping experience in an online discussion forum. Positive social influence was found to reinforce the relationship between beliefs about and attitude toward online shopping, as well as the relationship between attitude and intention to shop. We believe our alternative theory provides new insight into the complex processes through which social influence is brought to bear on consumers’ online shopping decisions. Implications of our work are discussed. 相似文献
992.
This paper considers the optimal control of convection–diffusion systems modeled by parabolic partial differential equations (PDEs) with time-dependent spatial domains for application to the crystal temperature regulation problem in the Czochralski (CZ) crystal growth process. The parabolic PDE model describing the temperature dynamics in the crystal region arising from the first principles continuum mechanics is defined on the time-varying spatial domain. The dynamics of the domain boundary evolution, which is determined by the mechanical subsystem pulling the crystal from the melt, are described by an ordinary differential equation for rigid body mechanics and unidirectionally coupled to the convection–diffusion process described by the PDE system. The representation of the PDE as an evolution system on an appropriate infinite-dimensional space is developed and the analytic expression and properties of the associated two-parameter semigroup generated by the nonautonomous operator are provided. The LQR control synthesis in terms of the two-parameter semigroup is considered. The optimal control problem setup for the PDE coupled with the finite-dimensional subsystem is presented and numerical results demonstrate the regulation of the two-dimensional crystal temperature distribution in the time-varying spatial domain. 相似文献
993.
Rajesh S. Prabhu Gaonkar Min Xie Kien Ming Ng Mohamed Salahuddin Habibullah 《Expert systems with applications》2011,38(11):13835-13846
System reliability assessment is one of the major acts in the operation and maintenance of every industrial and service sector, which also holds true for maritime transportation system. The complexity of the maritime transportation system is a prime obstacle in the evaluation of the operational reliability of the system; mainly due to the fact that statistical data on the important parameters and variables is scarce. This makes the application of fuzzy sets and fuzzy logic a viable option to overcome the data problem with regards to imprecision or vagueness in parameters and variables values. In this paper, the different decisive factors, affecting maritime transportation systems, are modeled in the form of linguistic variables. Techniques such as aggregation, mapping of fuzzy sets using distance measure and fuzzy logic rule base are used to arrive at subjective operational reliability value. The complete procedure is demonstrated with an example. 相似文献
994.
Man?Yeong?HaEmail author Joo?Goo?Kim 《Journal of Mechanical Science and Technology》2004,18(4):718-730
The solution for the natural convection in internally finned horizontal annuli is obtained by using a numerical simulation
of time-dependent and two-dimensional governing equations. The fins existing in annuli influence the flow pattern, temperature
distribution and heat transfer rate. The variations of the fin configuration suppress or accelerate the free convective effects
compared to those of the smooth tubes. The effects of fin configuration, number of fins and ratio of annulus gap width to
the inner cylinder radius on the fluid flow and heat transfer in annuli are demonstrated by the distribution of the velocity
vector, isotherms and streamlines. The governing equations are solved efficiently by using a parallel implementation. The
technique is adopted for reduction of the computation cost. The parallelization is performed with the domain decomposition
technique and message passing between sub-domains on the basis of the MPI library. The results from parallel computation reveal
in consistency with those of the sequential program. Moreover, the speed-up ratio shows linearity with the number of processor. 相似文献
995.
Colley CS Hebden JC Delpy DT Cambrey AD Brown RA Zibik EA Ng WH Wilson LR Cockburn JW 《The Review of scientific instruments》2007,78(12):123108
A time domain optical coherence tomography (OCT) system is described that uses mid-infrared light (6-8 microm). To the best of our knowledge, this is the first OCT system that operates in the mid-infrared spectral region. It has been designed to characterize bioengineered tissues in terms of their structure and biochemical composition. The system is based upon a free-space Michelson interferometer with a germanium beam splitter and a liquid nitrogen cooled HgCdTe detector. A key component of this work has been the development of a broadband quantum cascade laser source (InGaAs/AlInAs containing 11 different active regions of the three well vertical transition type) that emits continuously over the 6-8 microm wavelength range. This wavelength range corresponds to the so called "mid-infrared fingerprint region" which exhibits well-defined absorption bands that are specifically attributable to the absorbing molecules. Therefore, this technology provides an opportunity for optical coherence molecular imaging without the need for molecular contrast agents. Preliminary measurements are presented. 相似文献
996.
A. Senthil Kumar M. Rahman S.L. Ng 《The International Journal of Advanced Manufacturing Technology》2002,20(2):83-91
Machining of hardened steel and other difficult-to-cut materials requires instant heat transfer from the cutting edge of the
tool to improve tool life. Supply of high-volume and high-pressure coolant often provides the best answer. This paper deals
with an experimental investigation on the effect of high-pressure coolant on workpiece hardness, comparing it with dry cut
and conventional coolant. The effectiveness of high-pressure coolant is evaluated in terms of improvement of surface finish,
reduction in tool wear and cutting forces, and control of chip shape. It is found that the cutting force is reduced, surface
finish improved, and chip width is reduced with the use of high-pressure coolant. 相似文献
997.
Spectroscopic ellipsometry signals used in thin film analysis are dependent on the beam probe size. In this work, we report a technique to determine the beam size that uses the existing detection facilities in a spectroscopic ellipsometry setup without the need to rearrange the optical components. The intensity signal recorded with the technique comprises a coupled boundary diffraction and knife edge wave that can be isolated using nonlinear fitting. This then permitted an accurate measurement of the beam size with the stronger knife edge component. The technique has the added advantage of picking up chromatic aberration in the probing lens which may be a factor in ellipsometry measurement. 相似文献
998.
We investigate the stresses in thin films with sub-millimeter lateral spatial resolution using a dense array of prefabricated cantilever beams prepared by microelectromechanical-system techniques. Stress induced deflection of the cantilever is interrogated by an optical (laser/position sensitive detector) measurement system. Composition spread films are deposited on the cantilever array using a three gun on-axis magnetron cosputtering system. The position dependent composition is inferred using rate calibrations and verified by electron microprobe/energy dispersive spectroscopy. We demonstrate the function of this system using an Fe-Ni-Al composition spread with approximately 1 at. % resolution. This approach allows for measurement of the composition dependence of other electromechanical properties such as the martensitic phase transition temperature of traditional and ferromagnetic shape-memory alloys, as well as the properties of hydrogen storage materials and the magnetic response of magnetostrictive materials. 相似文献
999.
J. E. L. Simmons R. Dewar J. M. Ritchie Foo Meng Ng 《Journal of Mechanical Science and Technology》1998,12(1):1-11
Virtual Reality is a developing technology for which a range of applications are heing explored by different international
research groups. This paper describes recent research in the application of Virtual Reality to two important manufacturing
and assembly tasks which have a direct influence on the speed of introduction of new products. The tasks are the production
of planning documentation for assembled products and the design and planning of the cable harnesses which form part of all
electro-mechanical assemblies. The research completed so far demonstrates the potential of Virtual Reality, even at its current
stage of technological development, to make a significant contribution in both these cases. 相似文献
1000.
Yeong Sung Suh 《Journal of Mechanical Science and Technology》1998,12(4):572-582
In order to express the plastic-strain-induced anisotropy at finite deformation of ductile metals, a combined isotropic-kinematic
hardening model which is a particular form of anisotropic hardening, is an appropriate model because of its simple and convenient
mathematical formulation. This paper examines the applicability of the model in the computation of general straining problems
by performing a numerical tension-torsion test. The anisotropy generated by plastic flow is expressed by back stress. The
evolution equation contains form invariant isotropic functions of plastic strain rate and back stress and also involves the
spin associated with induced anisotropy. A numerical fitting procedure allowed us to show that circules modeled as combined
isotropic-kinematic hardening around the loading nose are in good agreement with the experimental yield loci taken from the
nonproportional straining. The measure of checking the applicability of combined isotropic-kinematic hardening by analyzing
the total stress history has also been demonstrated by simulating an extrusion process using the finite-element method. From
the computed results. the angle variations between the principal stress direction and the material direction, initially axial,
were observed if they are small enough in the active plastic deformation region to ensure that the stress point will move
along the part of the yield locus exhibiting nearly uniform curvature. This indicated that stress and deformation can be predicted
with combined isotropic-kinematic hardening as long as the loading is not reversed. 相似文献