Hong Kong Polytechnic University

About: Hong Kong Polytechnic University is a education organization based out in Hong Kong, China. It is known for research contribution in the topics: Tourism & Population. The organization has 29633 authors who have published 72136 publications receiving 1956312 citations. The organization is also known as: HKPU & PolyU.

Influence of Fly Ash as Cement Replacement on the Properties of Recycled Aggregate Concrete

Abstract: The use of high percentages of recycled aggregates in concrete would usually worsen the concrete properties. This paper tries to address the deficiency of the use of recycled aggregates by systematically presenting results on the influence of incorporating Class F fly ash on concrete properties. In this study, two series of concrete mixtures were prepared with water-to-binder (W/B) ratios of 0.45 and 0.55. The recycled aggregate was used as 0, 20, 50, and 100% by weight replacements of natural aggregate. In addition, fly ash was used as 0, 25, and 35% by weight replacements of cement. The results showed that the compressive strengths, tensile strengths, and static modulus of elasticity values of the concrete at all ages decreased as the recycled aggregate and the fly ash contents increased. Further, an increase in the recycled aggregate content decreased the resistance to chloride ion penetration and increased the drying shrinkage and creep of concrete. Nevertheless, the use of fly ash as a substitute for...

Image demosaicing: a systematic survey

Abstract: Image demosaicing is a problem of interpolating full-resolution color images from so-called color-filter-array (CFA) samples Among various CFA patterns, Bayer pattern has been the most popular choice and demosaicing of Bayer pattern has attracted renewed interest in recent years partially due to the increased availability of source codes/executables in response to the principle of "reproducible research" In this article, we provide a systematic survey of over seventy published works in this field since 1999 (complementary to previous reviews22, 67) Our review attempts to address important issues to demosaicing and identify fundamental differences among competing approaches Our findings suggest most existing works belong to the class of sequential demosaicing - ie, luminance channel is interpolated first and then chrominance channels are reconstructed based on recovered luminance information We report our comparative study results with a collection of eleven competing algorithms whose source codes or executables are provided by the authors Our comparison is performed on two data sets: Kodak PhotoCD (popular choice) and IMAX high-quality images (more challenging) While most existing demosaicing algorithms achieve good performance on the Kodak data set, their performance on the IMAX one (images with varying-hue and high-saturation edges) degrades significantly Such observation suggests the importance of properly addressing the issue of mismatch between assumed model and observation data in demosaicing, which calls for further investigation on issues such as model validation, test data selection and performance evaluation

A transparent, flexible, low-temperature, and solution-processible graphene composite electrode

Abstract: The synthesis and preparation of a new type of graphene composite material suitable for spin-coating into conductive, transparent, and flexible thin film electrodes in ambient conditions is reported here for the first time. Solution-processible graphene with diameter up to 50 mu m is synthesized by surfactant-assisted exfoliation of graphite oxide and in situ chemical reduction in a large quantity. Spin-coating the mixing solution of surfactant-functionalized graphene and PEDOT:PSS yields the graphene composite electrode (GCE) without the need for high temperature annealing, chemical vapor deposition, or any additional transfer-printing process. The conductivity and transparency of GCE are at the same level as those of an indium tin oxide (ITO) electrode. Importantly, it exhibits high stability (both mechanical and electrical) in bending tests of at least 1000 cycles. The performance of organic light-emitting diodes based on a GCE anode is comparable, if not superior, to that of OLEDs made with an ITO anode.