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compressive Strength, Pore Size Distribution and chloride-ion Penetration of Recycled Aggregate concrete Incorporating class-F Fly Ash

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Journal of Wuhan University of technology(Materials Science) 2006年第4期21卷 130-136页

作者：寇世聪 c S poon Department of civil and Structural Engineering The Hong Kong Polytechnic University Hung HomKowloon Hong Kong

the effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. two series of concrete mb：tures were prepared. the concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/ m^3 , respectively. the concrete rnixtures in series II had a water-to-binder ratio and a cement content of 0.45 and 400 kg/ ml respectively. Recycled aggregate was ased as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In cutdition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. the results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. the total porosity and average porosity diameter of the concrete increased us the recycled aggregate content increased. Furtherrruore , an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ush improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.

关键词： durability properties recycled aggregate concrete fly ash

Use of Recycled Glass in Architectural Mortars

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武汉理工大学学报 2010年第17期32卷 231-234,245页

作者： poon c S LING t c B Department of civil and Structural Engineering The Hong Kong Polytechnic UniversityHong KongChina

In recent years,recycled glass has been widely used as aggregate replacements in concrete. Owing to the aesthetic potential of the coloured recycled glass,this research aims to fully utilize this advantage for their higher end uses,such as architectural mortar. In this study,architectural white cement mortar was produced with a self consolidating method using recycled glass as the aggregate. An adequate amount of Metakaolin was incorporated into the mortar to mitigate the adverse effect of alkali-silica reaction. the results show that the self-compacting method is suitable to produce architectural mortar containing up to 100% recycled glass. Overall,the performance of all the architectural mortar mixtures in terms of both fresh and hardened properties was good.

关键词： recycled glass self-compacting architectural mortar ASR flexural strength

Generation and optical display of a binary-sampled phase-only hologram

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chinese Optics Letters 2016年第1期14卷 12-15页

作者： P. W. M. tsang Y.-t. chow t.-c. poon J.-P. Liu Department of Electronic Engineering City University of Hong Kong Hong Kong SAR China Bradley Department of Electrical and computer Engineering Virginia Tech Blacksburg VA 24061 USA Department of Photonics Feng Chia University No. 100 Wenhwa Rd. Taichung 407 China

Past research has demonstrated that a phase-only hologram can be obtained by down-sampling the intensity image of the object scene prior to the generation of the hologram. In this Letter, we extend the method to the generation of binary phase-only holograms. A hologram derived with our proposed method is referred to as a binary-sampled phase-only hologram （BSPOH）. Being different from the parent scheme, we have adopted an off- axis configuration in the generation of the BSPOH to avoid the quantization noise, the zeroth-order light, and the conjugate lights. An experimental evaluation reveals that the reconstructed image of the BSPOH is of good quality, and only contains slight amount of noise.

关键词： Bins Holographic displays Lithography

Pore Size Distribution of High Performance Metakaolin concrete

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Journal of Wuhan University of technology(Materials Science) 2002年第1期17卷 42-46页

作者： c.S.poon S.c.Kou L.Lam Department of civil and Structural Engineering The Hong Kong Polytechnic University Hong Kong China

the compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. concretes containing 0,5% , 10% and 20% metakaolin were prepared at a water / cementitious material ratio ( W/c) of 0. 30. In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison. the specimens were cured in water at 27℃ for 3 to 90 days. the results show that at the early age of curing (3 days and 7 days), metakaolin replacements increase the compressive strength, but silica fume replacement slightly reduces the compressive strength. At the age of and after 28 days , the compressive strength of the concrete with metakaolin and silica fume replacement increases. A strong reduction in the total porosity and average pore diameter were observed in the concrete with MK 20% and 10% in the first 7 days.

关键词： high performance concrete metakaolin pore size distribution

Quality control of Recycled Aggregates Derived from construction and Demolition Wastes

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四川大学学报（工程科学版） 2009年第3期41卷 248-257页

作者： poon chi-sun KOU Shi-cong Dept. of civil and Structural Engineering the Hong Kong Polytechnic Univ. Hung Horn Kowloon Hong Kong

In 2007,over 24 million tons of construction and Demolition(c&D) wastes were generated in Hong *** the local landfills will be saturated in about 6 years,it is important to find a viable way to reuse these waste materials as to alleviate the demand on public fill *** order to tackle the problem,the Hong Kong government has set up a temporary recycling facility in Hong Kong in 2002 for producing different sizes of recycled aggregate for use in various construction *** Hong Kong Polytechnic University has been studying the feasible use of recycled aggregates in Hong Kong for a number of years.A substantial amount of experimental results on the properties of recycled aggregates and the effect of recycled aggregates on the properties of concrete and other construction products(*** blocks and granular sub-base) has been *** this paper,the experience of Hong Kong in using recycled aggregates are summarized and a set of quality control guidelines proposed for governing the use of recycled aggregates in Hong Kong is *** experience and guidelines may also be useful for the recycling of waste materials derived from the recent Sichuan earthquake in china.

关键词：建筑物工程质量抗震设计建筑结构

Do specific ultrasonography features identified at the time of early pregnancy loss predict fetal chromosomal abnormality? e A systematic review and meta-analysis

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Genes & Diseases 2019年第2期6卷 129-137页

作者： J.Huang W.Zhu J.tang S.H.Saravelos L.c.Y.poon t.c.Li Department of Obstetrics and Gynaecology The First Affiliated Hospital of Chongqing Medical UniversityChongqing400016China Department of Obstetrics and Gynaecology The Chinese University of Hong KongHong Kong SARChina IVF Unit Hammersmith HospitalImperial College Healthcare NHS TrustLondonUK

to investigate the association of specific ultrasonography features identified during the diagnosis of early pregnancy loss(EPL)and abnormal *** was a systematic review and meta-analysis conducted in accordance with PRISMA *** searched PubMed,cochrane and Ovid MEDLINE from 1977 to Jan 2017 to identify the articles that described EPL with karyotype and ultrasonography *** differences were pooled to estimate the chromosomal abnormality rates in ultrasonography features,including pre-embryonic,enlarged yolk sac(YS),short crown rump length(cRL),small gestational sac(GS),symmetrical arrested growth embryo,or gestational sac with only a *** assessment of included studies was performed using Strengthening the Reporting of Observational Studies in Epidemiology(StROBE)checklists for Observational Studies(2007 version).thirteen studies were included in the *** abnormality was more likely to occur in embryonic EPL and enlarged *** the other hand,short cRL,small GS,symmetrical arrested growth embryo,or gestational sac with only a YS,were not associated with an increased risk of fetal chromosomal *** features at the time of diagnosis of EPL have limited predictive value of fetal chromosomal abnormality.

关键词： Ultrasonography Early pregnancy loss chromosomal abnormality Predictive value

An enhanced method for fast generation of hologram sub-lines

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chinese Optics Letters 2009年第12期7卷 1092-1096页

作者： P. W. M. tsang J. P. Liu K. W. K. cheung t.-c. poon Department of Electronic Engineering City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong SAR China Department of Photonics Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung 40724 China Bradley Department of Electrical and computer Engineering Virginia Tech Blacksburg Virginia 24061 USA

Sub-lines are one-dimensional diffraction patterns representing the light beams emerging from horizontal planes of an object image. Past research has demonstrated that the sub-lines can be encapsulated as a multi-bank filtering process, and implemented with a field programmable gate array （FPGA） device. As the complexity of the filters is high, their length and the number of input pins have to be reduced substantially, hence leading to degradation on the reconstructed images. We propose an enhanced method to overcome the problem by binarizing the filters＇ coefficients, and half-toning the pixel intensities of the object image. Experimental evaluation reveals that our method results in reconstructed images are superior to that obtained with the parent method.

关键词： Diffraction Field programmable gate arrays (FPGA) Holographic interferometry

Recent studies on mechanical properties of recycled aggregate concrete in china-A review

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Science china(technological Sciences) 2012年第6期55卷 1463-1480页

作者： XIAO JianZhuang LI WenGui poon chiSun Department of Building Engineering Tongji UniversityShanghai 200092China Department of civil and Structural Engineering Hong Kong Polytechnic UniversityHong KongChina committee of Recycled Aggregate concrete Civil Engineering SocietyShanghai 200092China

Numerous experimental and theoretical studies on recycled aggregate concrete have been carried out in china in the past 10 *** paper provides a comprehensive review of the related findings of research on the mechanical properties of RAc in *** influences of the RcA on the strength and deformation characteristics of concrete,the statistical characteristics for the strength of RAc,fracture energy,stress-strain relationships under uniaxial compression,uniaxial tension as well as pure shear,and the residual strength of RAc after exposure to high temperatures,the bond between RAc and different kinds of steel rebar were also ***,some recent studies on the numerical simulation of the failure mechanism for RAc at the meso-structure level were discussed.

关键词： construction and demolition (c&D) wastes recycled coarse aggregate (RcA) recycled aggregate concrete (RAc) me-chanical property test numerical simulation

Does supplier concentration matter to investors during the cOV1D-19 crisis:evidence from china?

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Financial Innovation 2022年第1期8卷 2289-2316页

作者： Louis t.W.cheng Jack S.c.poon Shaolong tang Jacqueline Wenjie Wang School of Business The Hang Seng University of Hong KongHong KongChina School of Accounting and Finance of the Hong Kong Polytechnic University Hong KongChina Division of Business and Management Beijing Normal University-Hong Kong Baptist UniversityUnited International CollegeZhuhaiChina

the literature shows that investor attention to customer–supplier disclosure increases when suppliers’information arrival is *** to the widespread of city lockdowns in china and the implementation of social distancing to control the cOVID-19 pandemic,investor attention to potential disruption of the supply chain spikes,leading to a price devaluation for firms with high supplier concentration *** find that a higher degree of supplier concentration is related to more serious stock price declines over the short-term and medium-term windows right after the Wuhan *** result lends support to the argument that the concentration risk of suppliers is a significant consideration for china stock market investors,especially under the potential financial distress at the firm level induced by the cOVID-19 crisis.

关键词： cOVID-19 Supplier concentration Supplier disclosure Stock price effect Industry neutral portfolio