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Hong Kong, China

Chu Hai College of Higher Education is a private degree-granting institute in Hong Kong. The college is best known for its journalism and Chinese history programmes. At present, Chu Hai College is recognised as an Approved Post Secondary College under the Post Secondary Colleges Ordinance . Wikipedia.

Wan K.T.,Chu Hai College of Higher Education | Leung C.K.Y.,Hong Kong University of Science and Technology
Sensors | Year: 2012

Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively. © 2012 by the authors. Source

Cheung V.S.-P.,Smart Energy | Chung H.S.-H.,Smart Energy | Lo A.W.-L.,Chu Hai College of Higher Education
IEEE Transactions on Power Electronics | Year: 2016

A modular and scalable voltage-regulation structure for enhancing service continuity and flexibly changing the system power rating is proposed. The methodology is based on paralleling multiple series-voltage compensators, namely multiparallel-connected series-voltage compensator (MSVC), to regulate the load voltage. The output voltage of each compensator is controlled locally by adjusting the phase angle of the output voltage of the inverter in each compensator, while the output current of each compensator is coupled to two adjacent compensators via two coupling transformers. The coupling transformers form a daisy-chained structure. The load current can be shared near-equally among the compensators through the transformer structure. The operating principle, steady-state and transient current-sharing characteristics of the architecture will be discussed and illustrated. A simplified design procedure will be given. A 3-kVA MSVC test bed with three parallel-connected single-phase compensator units has been built and evaluated. The response of the MSVC system with each compensator unit engaged and disengaged momentarily will be investigated. Such structure is applicable for regulating and stabilizing the supply voltage for consumers at the distribution side. © 1986-2012 IEEE. Source

Xu X.,City University of Hong Kong | Po L.-M.,City University of Hong Kong | Cheung K.-W.,Chu Hai College of Higher Education | Ng K.-H.,City University of Hong Kong | And 2 more authors.
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2012

The performance of view synthesis using depth image based rendering (DIBR) highly depends on the accuracy of depth map. Inaccurate boundary alignment between texture image and depth map especially for large depth discontinuities always cause annoying artifacts in disocclusion regions of the synthesized view. Pre-filtering approach and reliability-based approach have been proposed to tackle this problem. However, pre-filtering approach blurs the depth map with drawback of degradation of the depth map and may also cause distortion in non-hole region. Reliability-based approach uses reliable warping information from other views to fill up holes and is not suitable for the view synthesis with single texture video such as video-plus-depth based DIBR applications. This paper presents a simple and efficient depth map preprocessing method with use of texture edge information to refine depth pixels around the large depth discontinuities. The refined depth map can make the whole texture edge pixels assigned with foreground depth values. It can significantly improve the quality of the synthesized view by avoiding incorrect use of foreground texture information in hole filling. The experimental results show the proposed method achieves superior performance for view synthesis by DIBR especially for large baseline. © 2012 IEEE. Source

Liang Z.,Hong Kong Polytechnic University | Chi Z.,Hong Kong Polytechnic University | Fu H.,Hong Kong Polytechnic University | Fu H.,Chu Hai College of Higher Education | And 2 more authors.
Pattern Recognition | Year: 2012

As an important problem in image understanding, salient object detection is essential for image classification, object recognition, as well as image retrieval. In this paper, we propose a new approach to detect salient objects from an image by using content-sensitive hypergraph representation and partitioning. Firstly, a polygonal potential Region-Of-Interest (p-ROI) is extracted through analyzing the edge distribution in an image. Secondly, the image is represented by a content-sensitive hypergraph. Instead of using fixed features and parameters for all the images, we propose a new content-sensitive method for feature selection and hypergraph construction. In this method, the most discriminant color channel which maximizes the difference between p-ROI and the background is selected for each image. Also the number of neighbors in hyperedges is adjusted automatically according to the image content. Finally, an incremental hypergraph partitioning is utilized to generate the candidate regions for the final salient object detection, in which all the candidate regions are evaluated by p-ROI and the best match one will be the selected as final salient object. Our approach has been extensively evaluated on a large benchmark image database. Experimental results show that our approach can not only achieve considerable improvement in terms of commonly adopted performance measures in salient object detection, but also provide more precise object boundaries which is desirable for further image processing and understanding. © 2012 Elsevier Ltd. All rights reserved. Source

Cheung V.S.-P.,Smart Energy | Chung H.S.-H.,Smart Energy | Wang K.-W.,Smart Energy | Lo A.W.-L.,Chu Hai College of Higher Education
IEEE Transactions on Power Electronics | Year: 2014

A modular and scalable series compensation technique for enhancing controllability and flexibility in power transmission in distributed power systems is proposed. The concept is based on paralleling multiple static synchronous series compensators (SSSC) through daisy-chained transformers to perform reactive power compensation, and thus control the amount and direction of the power flow over the transmission link. Each compensator unit is under an autonomous control for regulating its output voltage. Its output current is coupled to another compensator unit through one of the daisy-chained transformers, so that the transmission current is shared among the parallel-connected compensators. Modeling, design, and analysis of a compensator unit and the proposed multiparallel-connected SSSC (MSSSC) architecture in an elementary two-machine system will be presented. A 3-kVA MSSSC test bed with three-parallel-connected compensator units for a single-phase system has been built and evaluated. The steady-state and transient current-sharing characteristics in forward and reverse power transmission over the transmission link will be studied. The response of the MSSSC system with each compensator unit engaged sequentially will also be investigated. © 2013 IEEE. Source

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