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Control of settlement and volume loss induced by tunneling under recently reclaimed land

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Underground Space 2019年第4期4卷 289-301页

作者： A.K.l.Kwong C.C.W.ng A.Schwob AECOM Hong KongChina Dragages-Bouygues Joint Venture Hong KongChina

The proposed Tuen Mun-Chek lap Kok link(TM-ClKl)project comprises a 9-km-long dual two-lane carriageway between Tuen Mun and North lantau,Hong *** of the two tunnels at the Northern landfall Fall was carried out by two TBMs:the northbound is referred to as Ml03 and has an excavated diameter of 17.63 m,and the southbound is referred to as Ml02 and has an excavated diameter of 14.00 *** use of TBMs minimized the amount of dredging and removal of soft marine deposits,resulting in less impact to the environment within and near the work site of the *** treatment in the form of deep vibro-compaction was carried out at the sand fill and band drains installed in the marine deposit.A surcharge was also added above the final formation level to limit the residual settlement and differential settlement of the reclaimed land to less than 500 mm and 1 in 300,respectively,for a design life of 50 *** element analyses were performed to predict the settlement trough under different confinement pressures along the tunnel *** monitoring of the ground movement was carried out during the driving of the two TBMs to ensure that the design confinement pressure of the slurry would not cause excessive settlement,heave,or blow out at the shallow tunnel sections or different facilities along the tunnel *** monitoring data was then used to back-calculate the percentage of volume loss,which is a key index describing the behavior of the ground during *** monitoring data showed that the measured settlement and back-calculated volume loss were much lower than the predicted values.

关键词： TBM excavation Settlement trough Volume loss Ground treatment Confinement pressure

A new green process for biodiesel production from waste oils via catalytic distillation using a solid acid catalyst-Modeling, economic and environmental analysis

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Green Energy & Environment 2016年第1期1卷 62-74页

作者： Aashish Gaurav Flora T.T.ng Garry l.Rempel Department of Chemical Engineering University of Waterloo

The challenges in the chemical processing industry today are environmental concerns, energy and capital costs. Catalytic distillation(CD) is a green reactor technology which combines a catalytic reaction and separation via distillation in the same distillation column. Utilization of CD in chemical process development could result in capital and energy savings, and the reduction of greenhouse gases. The efficacy of CD and the economic merits, in terms of energy and equipment savings, brought by CD for the production of biodiesel from waste oil such as yellow grease is quantified. Process flow sheets for industrial routes for an annual production of 10 million gallon ASTM purity biodiesel in a conventional process(reactor followed by distillation) and CD configurations are modeled in Aspen Plus. Material and energy flows, as well as sized unit operation blocks, are used to conduct an economic assessment of each process. Total capital investment, total operating and utility costs are calculated for each process. The waste oil feedstock is yellow grease containing both triglyceride and free fatty acid. Both transesterification and esterification reactions are considered in the process simulations. Results show a significant advantage of CD compared to a conventional biodiesel processes due to the reduction of distillation columns, waste streams and greenhouse gas emissions. The significant savings in capital and energy costs together with the reduction of greenhouse gases demonstrate that process intensification via CD is a feasible and new green process for the biodiesel production from waste oils.

关键词： Yellow grease Catalytic distillation Aspen plus economic analyzer Process intensification

A Nonstandard lévy-Khintchine Formula and lévy Processes

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Acta Mathematica Sinica,English Series 2008年第2期24卷 241-252页

作者： Siu Ah ng School of Mathematical Sciences University of KwaZulu-Natal Pietermaritzburg 3209 South Africa

We use methods from nonstandard analysis to obtain a short and simple derivation of the levy-Khintchine formula via an explicit construction of certain laws of the infinitesimal increments. Consequently, any arbitrary... 详细信息

关键词： levy processes levy-Khintchine formula nonstandard analysis infinitesimal hyperfinite

Three-dimensional biogenic C-doped Bi_2MoO_6/In_2O_3-ZnO Z-scheme heterojunctions derived from a layered precursor

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Journal of Environmental Sciences 2019年第5期31卷 54-66页

作者： Hongyan li Jia li Ping Yang Dickon H.l.ng Xinling Cui Fei Ji School of Material Science and Engineering University of Jinan Department of Physics The Chinese University of Hong Kong

Novel 3D biogenic C-doped Bi_2 MoO_6/In_2O_3-ZnO Z-scheme heterojunctions were synthesized for the first time, using cotton fiber as template. The as-prepared samples showed excellent adsorption and photodegradation performance toward the hazardous antibiotic doxycycline under simulated sunlight irradiation. The morphology, phase composition and in situ carbon doping could be precisely controlled by adjusting processing parameters. The carbon doping in Bi_2 MoO_6/In_2O_3-ZnO was derived from the cotton template, and the carbon content could be varied in the range 0.9–4.4 wt.% via controlling the heat treatment temperature. The sample with Bi_2 MoO_6/In_2O_3-ZnO molar ratio of 1:2 and carbon content of1.1 wt.% exhibited the highest photocatalytic activity toward doxycycline degradation,which was 3.6 and 4.3 times higher than those of pure Bi_2 MoO_6 and Zn In Al-ClDH(calcined layered double hydroxides), respectively. It is believed that the Z-scheme heterojunction with C-doping, the 3D hierarchically micro–meso–macro porous structure, as well as the high adsorption capacity, contributed significantly to the enhanced photocatalytic activity.

关键词： Biotemplate Bi2MoO6 ZnInAl-layered double hydroxides (lDH) Adsorption Photocatalysis

NUMERICAl STUDIES OF A ClASS OF COMPOSITE PRECONDITIONERS

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Journal of Computational Mathematics 2014年第2期32卷 136-151页

作者： Qiang Niu Michael ng Mathematics and Physics Centre Xi'an Jiaotong-Liverpool University Suzhou 215123 China Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong

In this paper, we study a composite preconditioner that combines the modified tangential frequency filtering decomposition with the IlU（O） factorization. Spectral property of the composite preconditioner is examined by the approach of Fourier analysis. We illustrate that condition number of the preconditioned matrix by the composite preconditioner is asymptotically bounded by O（hp -2/3） on a standard model problem. Performance of the composite preconditioner is compared with other preconditioners on several problems arising from the discretization of PDEs with discontinuous coefficients. Numerical results show that performance of the proposed composite preconditioner is superior to other relative preconditioners.

关键词： Preconditioner IlU Tangential frequency filtering decomposition GMRES.

Compressive properties of a novel slurry-infiltrated fiber concrete reinforced with arc-shaped steel fibers

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第6期24卷 543-556页

作者： Hedong lI Yabiao lI Yunfeng PAN P.l.ng Christopher K.Y.lEUng Xin ZHAO School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Civil Engineering The University of Hong KongHong Kong 999077China Faculty of Civil Engineering Vilnius Gediminas Technical UniversityVilnius LT-10223Lithuania Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou 310023China

Slurry-infiltrated fiber concrete(SIFCON)is a sort of strain hardening cement-based composite material,typically made with 5%–20%steel *** study focused on a novel type of SIFCON in which hooked-end steel fibers were replaced by arc-shaped steel *** quasi-static compressive properties of the SIFCON were first *** results suggested that using arc-shaped steel fibers in lieu of hooked-end steel fibers increased the quasi-static compressive strength by 47.1%and the strain at peak stress by 56.3%.We attribute these improvements to new crack-resisting mechanisms,namely“fiber crosslock”,“dual bridging”,and“confinement loops”,when the arc-shaped steel fibers are introduced into *** high impact resistance is a special property of SIFCON that is of practical significance,the dynamic compressive properties of arc-shaped steel fiber SIFCON were studied by using an 80-mm-diameter split Hopkinson pressure bar(SHPB).The results showed that the dynamic compressive strength,dynamic increase factor(DIF),and dynamic toughness of SIFCON all increased with the strain *** SIFCON incorporating arc-shaped steel fibers proved to have significant advantages in structural applications requiring high impact resistance.

关键词： Slurry-infiltrated fiber concrete(SIFCON) Arc-shaped steel fiber Quasi-static compressive properties Spilt Hopkinson pressure bar(SHPB) Dynamic compressive properties

Contribution of Plant Breeding Efforts to the Safety of the Cereal-based Food Chain

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食品科学 2006年第11期27卷 618-620页

作者： Zoltán Bedo Mariann Rakszegi lászló láng Peter Shewry Agricultural Research Institute of the Hungarian Academy of SciencesMartonvásárHungary

A comprehensive food safety strategy requires the establishment of a farm-to-fork traceability system, which allows each step in the food chain to be followed and identified. This policy requires a multidisciplinary scientific approach including the wide range of technological knowledge necessary to maintain the safety of the whole food chain. With the introduction of the sustainability concept considerable changes have taken place in food *** priorities have been raised nowadays due to increasing concern for environmental protection and healthy food production. These new priorities, which have led to the agricultural sector developing a more multifunctional character,are based on new social demands in relation to food production, where the essential criteria are to provide nutritious foodstuffs free of dangerous substances and to use environment-friendly technologies which ensure sustainability.……

关键词： In Contribution of Plant Breeding Efforts to the Safety of the Cereal-based Food Chain

High mechanical strengths and ductility of stainless steel 304l fabricated using selective laser melting

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Journal of Materials Science & Technology 2019年第2期35卷 388-394页

作者： Q.B.nguyen Z.Zhu F.l.ng B.W.Chua S.M.l.Nai J.Wei Singapore Institute of Manufacturing Technology Institute of Research and Development Duy Tan University

Achieving not only high mechanical strengths but also high ductility is recently established using an additive manufacturing technique called selective laser melting. In the present study, stainless steel 304 l fully dense samples were successfully printed using the 3 D systems – ProX 300 printing machine. The ductility and tensile yield strength were almost two and three times higher compared to those of ASTM cast's alloy. Honey comb like nano-cellular structure with different orientation was observed in the fine grains(~4μm) due to fast cooling rate. In addition, the formation of martensite phase in random grains is also a contributor to the strengths. Furthermore, negative residual stresses in the build and horizontal directions were detected and assisted further increase in the tensile strength. Fractography revealed the ductile feature of plastic deformation and the crack openings at unmelted particles or pores.

关键词： Additive manufacturing Stainless steel Powder Selective laser melting

Evaluation of solubility of polycyclic aromatic hydrocarbons in ethyl lactate/water versus ethanol/water mixtures for contaminated soil remediation applications

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Journal of Environmental Sciences 2012年第6期24卷 1064-1075页

作者： Chiew lin Yap Suyin Gan Hoon Kiat ng Department of Chemical and Environmental Engineering The University of Nottingham Malaysia CampusJalan Broga43500 SemenyihSelangor Darul EhsanMalaysia Department of Mechanical Materials and Manufacturing Engineering The University of Nottingham l~lalaysia Campus Jalan Broga 43500 Semenyih Selangor Darul Ehsan Malaysia

Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil *** solubilities of phenanthrene,anthracene,fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium *** cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from *** ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by 〉 4 orders of magnitude above the levels obtained with water ***,ethyl lactate demonstrated a greater capacity to enhance PAH solubility than *** cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope （σ） and the end-to-half slope （σ 0.5） of the solubilisation curve were 1.0-1.5 and 2.0-2.9 higher than ethanol/water system *** line with this,ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%-37% and 18%-61% higher compared to ethanol/water system in low organic content and high organic content soils respectively,with a 2：1 （V/W） ratio of solution：soil and with cosolvent fraction as low as *** the exception of benzo[a]pyrene,the experimental desorption results agreed fairly with the predicted values,under an applied solution：soil ratio that was enough to hold the capacity of released contaminants.

关键词： polycyclic aromatic hydrocarbon solubility desorption ethyl lactate ethanol