Yang Y.,Guangdong Ocean University |
Chan W.Y.,Tat Chee Avenue |
Wu C.L.,Louisiana State University |
Kong R.Y.C.,City University of Hong Kong |
Lai A.C.K.,Tat Chee Avenue
Journal of the Royal Society Interface | Year: 2012
There has been increasing interest in the use of upper-room ultraviolet germicidal irradiation (UVGI) because of its proven effectiveness in disinfecting airborne pathogens. An improved drift flux mathematical model is developed for optimizing the design of indoor upper-room UVGI systems by predicting the distribution and inactivation of bioaerosols in a ventilation room equipped with a UVGI system. The model takes into account several bacteria removal mechanisms such as convection, turbulent diffusion, deposition and UV inactivation. Before applying the model, the natural die-off rate and susceptibility constants of bioaerosols were measured experimentally. Two bacteria aerosols, Escherichia coli and Serratia marcescens, were tested for this purpose. It was found out that the general decay trend of the bioaerosol concentration predicted by the numerical model agrees well with the experimental measurements. The modelling results agree better with experimental observations for the case when the UVGI inactivation mechanism dominates at the upper-room region than for the case without UVGI. The numerical results also illustrate that the spatial distribution of airborne bacteria was influenced by both air-flow pattern and irradiance distribution. In addition to predicting the local variation of concentration, the model assesses the overall performance of an upper-room UVGI system. This model has great potential for optimizing the design of indoor an upper-room UVGI systems. © 2012 The Royal Society.
Chin K.-S.,Tat Chee Avenue |
Lo K.-C.,City University of Hong Kong |
Leung J.P.F.,City University of Hong Kong
Expert Systems with Applications | Year: 2010
Confronting fierce global competition, organizations have implemented knowledge management to enhance competitive advantages. With increasing investments in resources for knowledge management implementation in many organizations, measuring knowledge management performance has become an important agenda among researchers and practitioners. However, the current knowledge management performance measurement methods cannot truly report the results of organizations' knowledge management efforts. To address this problem, there is a need of a better approach for measuring knowledge management performance in organizations. This paper presents the authors' recent research in using a K-user satisfaction based approach and evidential reasoning methodology to develop a user-satisfaction-based knowledge management performance measurement system for organizations to identify strengths and weaknesses, as well as enhance continuous learning. A case study in applying the developed system and methodology in primary school education has been conducted to demonstrate its effectiveness. © 2009 Elsevier Ltd. All rights reserved.
Ma X.,City University of Hong Kong |
Liu W.,City University of Hong Kong |
Du X.,City University of Hong Kong |
Liu X.,City University of Hong Kong |
And 3 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2010
Wafer bonding and layer transfer are two fundamental technologies in the fabrication of advanced microsystems. In the authors' experiments, prior to Ge wafer bonding, the hydrophilicity of the germanium surface after wet chemical treatment and O2/N2 plasma activation is evaluated by contact angle measurement. The effects and mechanism of wet or dry treatments on the Ge surface roughness are also characterized. The results are used to tailor the Ge- SiO2 direct bonding process. Finally, oxygen plasma activation for 10 s and B+ / H+ coimplantation are employed to facilitate Ge- SiO2 direct bonding and Ge layer transfer at a low temperature. In comparison with hydrogen only ion implantation using the same fluence, coimplantation of B+ and H+ decreases the layer transfer temperature from over 400-320 °C. © 2010 American Vacuum Society.
Li F.,Aerospace Combined Environment Laboratory |
Pecht M.,Tat Chee Avenue |
Lau D.,Tat Chee Avenue |
Niu G.,Tat Chee Avenue
Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010 | Year: 2010
This paper has a research on the method of life consumption monitoring based on physics of failure aim at the electronic product. This method that is on the basis of failure modes, mechanisms and effects analysis(FMMEA) takes environmental stress as input, combined with the products' structure character, it determines the time (or cycles) to failure under certain environmental stress using failure models, then it estimates the life consumption using damage accumulation models. For improving the accuracy and the real-time ability in monitoring, this context has a deep study on the data reduction and the forms of damage accumulating. The method is applied on a cert. © 2010 IEEE.
Han N.,Tat Chee Avenue |
Wang F.,City University of Hong Kong |
Hou J.J.,Tat Chee Avenue |
Xiu F.,Tat Chee Avenue |
And 4 more authors.
ACS Nano | Year: 2012
Due to the extraordinary large surface-to-volume ratio, surface effects on semiconductor nanowires have been extensively investigated in recent years for various technological applications. Here, we present a facile interface trapping approach to alter electronic transport properties of GaAs nanowires as a function of diameter utilizing the acceptor-like defect states located between the intrinsic nanowire and its amorphous native oxide shell. Using a nanowire field-effect transistor (FET) device structure, p- to n-channel switching behaviors have been achieved with increasing NW diameters. Interestingly, this oxide interface is shown to induce a space-charge layer penetrating deep into the thin nanowire to deplete all electrons, leading to inversion and thus p-type conduction as compared to the thick and intrinsically n-type GaAs NWs. More generally, all of these might also be applicable to other nanowire material systems with similar interface trapping effects; therefore, careful device design considerations are required for achieving the optimal nanowire device performances. © 2012 American Chemical Society.