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Development of a system configuration for a solar powered hydrogen facility using fuzzy logic control

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第11期14卷 822-834页

作者： Ying-tai LOONG Mahidzal DAHARI Hwa-jen YAP Hue-yee CHONG Department of Mechanical Engineering Faculty of Engineering University MalayaKuala Lumpur 50603 Malaysia

Solar energy is a natural resource which can be harnessed to provide clean electricity for hydrogen production ***, this technology is not widely used because of control issues, particularly for hydrogen refuelling stations. At present,direct or DC-DC converter couplings are the most common system configurations for hydrogen refuelling stations. However, these system configurations are costly and suffer from gas shortage at hydrogen refuelling stations. Furthermore, the hydrogen produced by such system configurations varies considerably depending on the levels of solar radiation. In order to address these issues, a new system configuration is proposed, incorporating the feedback signal of the storage level in the control system. The photovoltaic(PV) system, electrolyzer, and storage tank are integrated with a fuzzy logic controller(FLC) to determine the backup current compensation for electrolyzer operation in order to obtain the minimum power required for hydrogen production. The proposed FLC is constructed with three input variables which are the PV current, hydrogen storage level, and the battery state of charge. The rules-based fuzzy inference process is based on the proposed configuration which combines the advantages of direct and DC-DC converter coupling configurations. The simulation results show that the proposed configuration offers better adaptability to variable radiation conditions compared to other methods. This gives a more promising option for ensuring the adequacy of hydrogen supply at hydrogen refuelling stations.

关键词： Hydrogen energy Solar energy Hydrogen refueling facility Fuzzy logic

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Graphical password： prevent shoulder-surfing attack using digraph substitution rules

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Frontiers of Computer Science 2017年第6期11卷 1098-1108页

作者： Lip yee POR chin Soon KU Amanul ISLAM Tan Fong ANG Department of Computer Science and Information Technology University of Malaya Kuala Lumpur 50603 Malaysia Department of Computer Science Universiti Tunku Abdul Rahman (Jalan Universiti) Kampar 31900 Malaysia

In this paper, a new scheme that uses digraph substitution rules to conceal the mechanism or activity re- quired to derive password-images is proposed. In the pro- posed method, a user is only required to click on one of the pass-image instead of both pass-images shown in each chal- lenge set for three consecutive sets. While this activity is sim- ple enough to reduce login time, the images clicked appear to be random and can only be obtained with complete knowl- edge of the registered password along with the activity rules. Thus, it becomes impossible for shoulder-surfing attackers to obtain the information about which password images and pass-images are used by the user. Although the attackers may know about the digraph substitution rules used in the pro- posed method, the scenario information used in each chal- lenge set remains. User study results reveal an average login process of less than half a minute. In addition, the proposed method is resistant to shoulder-surfing attacks.

关键词： graphical password authentication shoulder-surfing data and computer security digraph substitution rules

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Effect of pH on the photocatalytic removal of silver ions byβ-MnO2 particles

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International Journal of Minerals,Metallurgy and Materials 2021年第2期28卷 325-334页

作者： Sin-Ling chiam Anh Thi Le Swee-Yong Pung Fei-yee Yeoh School of Materials and Mineral Resources Engineering Engineering CampusUniversiti Sains Malaysia14300 Nibong TebalPulau PinangMalaysia

The presence of silver ions(Ag(I))in wastewater has a detrimental effect on living *** of soluble silver,especially at low concentrations,is *** paper presents the use ofβ-MnO2 particles as a photocatalyst to remove Ag(I)ions selectively from aqueous solution at various pH *** coupled plasma mass spectrometry(ICP-MS),X-ray diffraction(XRD),field emission electron microscope(FESEM),transmission electron microscopy(TEM),and X-ray photoelectron microscopy(XPS)were employed to determine the removal efficiency and to characterize the deposition of silver onto the surface ofβ-MnO2 *** optimum pH for the removal of Ag(I)ions was at pH 4 with 99%removal efficiency under 1 h of visible light *** phenomenon can be attributed to the electrostatic attraction betweenβ-MnO2 particles and Ag(I)ions as well as the suppression of electron–hole recombination in the presence of H+ions.

关键词： manganese oxide(MnO2) silver metal ion removal photocatalyst

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Polyvinylpyrrolidone-based bioink:influence of bioink properties on printing performance and cell proliferation during inkjet-based bioprinting

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Bio-Design and Manufacturing 2023年第6期6卷 676-690页

作者： Wei Long Ng Xi Huang Viktor Shkolnikov Ratima Suntornnond Wai yee Yeong HP-NTU Digital Manufacturing Corporate Lab Nanyang Technological University(NTU)Singapore 637460Singapore Singapore Centre for 3D Printing(SC3DP) School of Mechanical and Aerospace EngineeringNanyang Technological University(NTU)Singapore 639798Singapore HP Inc. Palo AltoCA 94304USA

Among the different bioprinting techniques,the drop-on-demand(DOD)jetting-based bioprinting approach facilitates contactless deposition of pico/nanoliter droplets ofmaterials and cells for optimal cell–matrix and cell–cell *** bioinks play a critical role in the bioprinting process,there is a poor understanding of the influence of bioink properties on printing performance(such as filament elongation,formation of satellite droplets,and droplet splashing)and cell health(cell viability and proliferation)during the DOD jetting-based bioprinting *** inert polyvinylpyrrolidone(PVP360,molecular weight=360 kDa)polymerwas used in this study to manipulate the physical properties of the bioinks and investigate the influence of bioink properties on printing performance and cell *** experimental results showed that a higher bioink viscoelasticity helps to stabilize droplet filaments before rupturing from the nozzle *** highly stretched droplet filament resulted in the formation of highly aligned“satellite droplets,”which minimized the displacement of the satellite droplets away from the predefined ***,a significant increase in the bioink viscosity facilitated droplet deposition on the wetted substrate surface in the absence of splashing and significantly improved the accuracy of the deposited main *** analysis showed that cell-laden bioinks with higher viscosity exhibited higher measured average cell viability(%),as the presence of polymer within the printed droplets provides an additional cushioning effect(higher energy dissipation)for the encapsulated cells during droplet impact on the substrate surface,improves the measured average cell viability even at higher droplet impact velocity and retains the proliferation capability of the printed *** the influence of bioink properties(e.g.,bioink viscoelasticity and viscosity)on printing performance and cell proliferation is important for the formulation

关键词： Biofabrication 3D bioprinting Drop-on-demand bioprinting Bioink properties Polyvinylpyrrolidone

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Noise robustness of an operational modal-based structural damage-detection scheme using impact-synchronous modal analysis

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第9期24卷 782-800页

作者： Pei Yi SIOW Zhi Chao ONG Shin yee KHOO Kok-Sing LIM Department of Mechanical Engineering Faculty of EngineeringUniversiti MalayaKuala Lumpur 50603Malaysia Photonics Research Centre Deputy Vice Chancellor(Research and Innovation)OfficeUniversiti MalayaKuala Lumpur 50603Malaysia

Data-driven damage-detection schemes are usually unsupervised machine-learning models in practice,as these do not require any ***-based features are commonly used in these schemes but often require several other parameters to accurately correlate with damage,as they may not globally represent the model,making them less sensitive to *** data,such as frequency response functions(FRFs)and principal component analysis(PCA)reduced FRFs(PCA-FRFs),inherits the dynamic characteristics of the structure,and it changes when damage occurs,thus showing sensitivity to ***,noise from the environment or external sources such as wind,operating machines,or the in-service system itself,can reduce the modal data's sensitivity to damage if not handled properly,which affects damage-detection *** study proposes a noise-robust operational modal-based structural damage-detection scheme that uses impact-synchronous modal analysis(ISMA)to generate clean,static-like FRFs for damage *** allows modal data collection without requiring shutdown conditions,and its denoising feature aids in generating clean,static-like FRFs for damage *** results showed that the FRFs obtained through ISMA under noise conditions have frequency response assurance criterion(FRAC)and cross signature assurance criterion(CSAC)scores greater than 0.9 when compared with FRFs obtained through experimental modal analysis(EMA)under static conditions;this validates the denoising feature of *** the denoised FRFs are reduced to PCA-FRFs and used in an unsupervised learning-based damage-detection scheme,zero false alarms occur.

关键词： Impact-synchronous modal analysis(ISMA) Frequency response function(FRF) Principal component analysis(PCA) Unsupervised learning Damage detection

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Amine-based solvent for CO_2 absorption and its impact on carbon steel corrosion: A perspective review

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chinese Journal of Chemical Engineering 2020年第5期28卷 1357-1367页

作者： Zhe Lun Ooi Pui yee Tan Lian See Tan Swee Pin Yeap Department of Chemical&Petroleum Engineering Faculty of EngineeringTechnology&Built EnvironmentUCSI University56000Cheras Kuala LumpurMalaysia Department of Chemical Process Engineering Malaysia–Japan International Institute of TechnologyUniversiti Teknologi MalaysiaJalan Sultan Yahya Petra54100 Kuala LumpurMalaysia

Carbon dioxide(CO2)is one of the commonly emitted gaseous by-products in industrial *** CO2 gas is the main cause to greenhouse effect,various CO2 capture technologies have been proposed and implemented to sequester the CO2 before the waste gases being released into the *** of the mature technologies for CO2 absorption is by using amine-based *** this regard,different single amine solvents or blended amine solvents have been proven for their capability to remove ***,the dissolution and reaction of CO2 gas with the amine solvents turn the solution *** phenomenon is undesired as it posts corrosion problem to the absorption column,which normally built of carbon steel ***,understanding the behaviour of different amine-based solvents in absorbing CO2 and its subsequent impact on carbon steel corrosion is very *** this review article,we will outline some of the more commonly used solvents and their respective advantages and disadvantages,motivating further investigation into the corrosion ***,existing gaps in this research area are discussed for future investigation.

关键词： Greenhouse gases PCCC technology Amine solvent Corrosion rate Carbon steel

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Low-thermal-budget electrically active thick polysilicon for CMOS-First MEMS-last integration

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Microsystems & Nanoengineering 2024年第3期10卷 395-407页

作者： Aron Michael Ian Yao-Hsiang Chuang Chee yee Kwok Kazuo Omaki UNSW SydneyNSW 2052Australia

Low-thermal-budget,electrically active,and thick polysilicon films are necessary for building a microelectromechanical system(MEMS)on top of a complementary metal oxide semiconductor(CMOS).However,the formation of these polysilicon films is a challenge in this ***,for the first time,the development of in situ phosphorus-doped silicon films deposited under ultrahigh-vacuum conditions(~10^(−9)Torr)using electron-beam evaporation(UHVEE)is *** process results in electrically active,fully crystallized,low-stress,smooth,and thick polysilicon films with low thermal *** crystallographic,mechanical,and electrical properties of phosphorus-doped UHVEE polysilicon films are *** films are compared with intrinsic and boron-doped UHVEE silicon *** spectroscopy,X-ray diffraction(XRD),transmission electron microscopy(TEM)and atomic force microscopy(AFM)are used for crystallographic and surface morphological *** curvature,cantilever deflection profile and resonance frequency measurements are employed to study the mechanical properties of the ***,resistivity measurements are conducted to investigate the electrical properties of the *** vertical,high-aspectratio micromachining of UHVEE polysilicon has been developed.A comb-drive structure is designed,simulated,fabricated,and characterized as an actuator and inertial sensor comprising 20-μm-thick in situ phosphorus-doped UHVEE films at a temperature less than 500℃.The results demonstrate for the first time that UHVEE polysilicon uniquely allows the realization of mechanically and electrically functional MEMS devices with low thermal budgets.

关键词： budget thick thermal

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Variable High Order Multiblock Overlapping Grid Methods for Mixed Steady and Unsteady Multiscale Viscous Flows

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Communications in Computational Physics 2009年第2期5卷 730-744页

作者： Bjorn Sjogreen H.C.yee Center for Applied Scientific Computing Lawrence Livermore National LaboratoryLivermoreCA 94551USA NASA Ames Research Center Moffett FieldCA 94035USA

Flows containing steady or nearly steady strong shocks on parts of the flow field,and unsteady turbulence with shocklets on other parts of the flow field are difficult to capture accurately and efficiently employing the same numerical scheme,even under the multiblock grid or adaptive grid refinement *** sixthorder or higher-order shock-capturing methods are appropriate for unsteady turbulence with shocklets,third-order or lower shock-capturing methods are more effective for strong steady or nearly steady shocks in terms of *** order to minimize the short comings of low order and high order shock-capturing schemes for the subject flows,a multiblock overlapping grid with different types of spatial schemes and orders of accuracy on different blocks is *** recently developed single block high order filter scheme in generalized geometries for Navier Stokes and magnetohydrodynamics systems is extended to multiblock overlapping grid *** first stage in validating the high order overlapping approach with several test cases is included.

关键词： Multiblock grid overset grids high order numerical methods blunt body hypersonic flows mixed steady and unsteady flows

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The current role of radiofrequency ablation in the treatment of hepatocellular carcinoma

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Hepatobiliary & Pancreatic Diseases International 2017年第2期16卷 122-126页

作者： Wan yee Lau Stephanie Hiu Yan Lau Faculty of Medicine The Chinese University of Hong Kong Shatin New Territories Hong Kong SAR China

Local ablative therapy is used in treating liver tumors by either injection of cytotoxic agents（chemicals,radioactive isotopes,hyperthermic agents or chemotherapeutic agents）or application of an energy source to ach... 详细信息

关键词： HCC The current role of radiofrequency ablation in the treatment of hepatocellular carcinoma RFA

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The Rise of china As A Major Host Destination for International Student Education

The Rise of China As A Major Host Destination for Internatio...

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作者： Audrey yee 上海交通大学

学位级别：硕士

International student mobility figures have exponentially increased over the years,doubling from 2.1 million in 2000 to close to 5 million in 2014 *** OECD projects this figure to reach 8 million in *** opening up its market in 1978 and making rapid developments in its economy,china has seen remarkable progress in its education *** much so,it has recently emerged as one of the top ten destinations for international students *** central objective of this paper hence,is to examine the rise of china as major host destination for international student *** the theoretical approach of a developmental state,china’s rise would be attributed to its strategies employed by the chinese state and universities that are used to enhance or create its attraction factors（otherwise known as “pull” factors）as identified in international student opinion surveys,that are of economic,educational and socio-cultural *** supplementing the above primary objective,the paperthen demonstrates that china’s success in the international student education market owing to the choice of strategies and motivations are indeed ***,itdeviates from the global neo-liberalism ideology,which otherwise sees pursuit of economic gain as ***-medium master programmes are also an emerging trend amongst chinese universities in attracting international *** paper will add on to the scarce literature available by prescribing some exploratory factors as to why some of these new programmes are more successful in attracting international students than others,through case studies of four such programmes that are from two C9 universities.

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