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Shape memory behavior of SMPU knitted fabric

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第5期8卷 830-834页

作者： chung Aggie Institute of Textile and Clothing The Hong Polytechnic UniversityHong KongChina

A preliminary investigation of shape memory (SM) effects of SMPU (shape memory polyurethane) knitting fabric is presented in this paper. Three SMPU knitted fabrics series with different content of SMPU fibers: 100% SMPU, 50% SMPU and 50% cotton, 16% SMPU and 84% cotton are designed and manufactured in our lab. Their shape memory behaviors at different temperatures are characterized in terms of bagging. Our experimental results showed that shape memory effect can be improved with increasing content of SMPU fibers. A comparison between Lycra and SMPU knitted fabrics was also made to validate the shape memory effects of SMPU knitted fabrics.

关键词： SMPU (shape memory polyurethane) fiber Shape memory (SM) Bagging Recovery

A Data Transmission Method Using a Cyclic Redundancy Check and Inaudible Frequencies

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Journal of Electronic Science and Technology 2016年第1期14卷 32-36页

作者： Myoungbeom chung the Division of Computer Engineering Sungkyul University

This paper describes a data transmission method using a cyclic redundancy check and inaudible *** proposed method uses inaudible high frequencies from 18 k Hz to 22 k Hz generated via the inner speaker of smart *** the proposed method,the performance is evaluated by conducting data transmission tests between a smart book and smart *** test results confirm that the proposed method can send 32 bits of data in an average of 235 ms,the transmission success rate reaches 99.47%,and the error detection rate of the cyclic redundancy check is0.53%.

关键词： Cyclic redundancy check data transmission method high frequency inaudible frequencies

Self-sensing concrete:from resistance-based sensing to capacitance-based sensing

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International Journal of smart and Nano Materials 2021年第1期12卷 1-19页

作者： D.D.L.chung Composite Materials Research Laboratory Department of Mechanical and Aerospace EngineeringUniversity at Buffalothe State University of New YorkBuffaloNYUSA

Self-sensing uses the cement-based material without sensor incor-poration to sense *** paper reviews self-sensing cementbased materials,with coverage of the well-studied resistance-based sensing as well as the less-studied capacitance-based *** review is the first that covers capacitance-based ***-based sensing is advantageous over resistance-based sensing in that no particular admixture is required,so that it is applicable to both existing and new *** contrast,resis-tancebased sensing that is comparable to capacitance-based sen-sing in stress/strain sensitivity requires conductive admixtures,such as carbon ***-based strain sensing is based on piezo-resistivity,which is associated with the resistance increasing upon tension and decreasing upon ***-based strain sensing is based on piezopermittivity,which is associated with the permittivity decreasing upon tension and increasing upon *** causes the resistance to increase and causes the permittivity to *** in temperature decreases the resistance but increases the *** review also covers the methodology of the electrical measurements.

关键词： Cement concrete sensing resistance capacitance

Small-signal Stability Criteria in Power Electronics-dominated Power Systems:A Comparative Review

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1003-1018页

作者： Qifan Chen Siqi Bu Chi Yung chung Department of Electrical and Electronic Engineer The Hong Kong Polytechnic UniversityHong KongChina Department of Electrical and Electronic Engineering Shenzhen Research InstituteCentre for Grid ModernisationInternational Centre of Urban Energy NexusCentre for Advances in Reliability and SafetyResearch Institute for Smart Energyand Policy Research Centre for Innovation and TechnologyThe Hong Kong Polytechnic UniversityHong KongChina

To tackle emerging power system small-signal stability problems such as wideband oscillations induced by the large-scale integration of renewable energy and power electronics,it is crucial to review and compare existing small-signal stability analysis *** this basis,guidance can be provided on determining suitable analysis methods to solve relevant small-signal stability problems in power electronics-dominated power systems(PEDPSs).Various mature methods have been developed to analyze the small-signal stability of PEDPSs,including eigenvalue-based methods,Routh stability criterion,Nyquist/Bode plot based methods,passivity-based methods,positive-net-damping method,lumped impedance-based methods,bifurcation-based methods,*** this paper,the application conditions,advantages,and limitations of these criteria in identifying oscillation frequencies and stability margins are reviewed and compared to reveal and explain connections and discrepancies among ***,efforts are devoted to mathematically proving the equivalence between these small-signal stability ***,the performance of these criteria is demonstrated and compared in a 4-machine 2-area power system with a wind farm and an IEEE 39-bus power system with 3 wind farms.

关键词： Impedance-based method oscillation analysis power electronic converter power electronics-dominated power system renewable power generation small-signal stability

Effects of TiC on the microstructure refinement and mechanical property enhancement of additive manufactured Inconel 625/TiC metal matrix composites fabricated with novel core-shell composite powder

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Journal of Materials Science & Technology 2023年第33期164卷 13-26页

作者： Taegyu Lee Wonjong Jeong SeungHyeok chung Ho Jin Ryu Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyYu Seong-GuDae Hak-Ro 29134141 DaejeonRepublic of Korea Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and TechnologyYu Seong-GuDae Hak-Ro 29134141 DaejeonRepublic of Korea

The flexible product shape of additive manufacturing(AM)is attractive,but the process suffers from a lack of material property diversity due to a limited number of printable alloys and post-processing *** overcome this problem,the AM of metal matrix composites(MMCs)is a highly suitable solution because the properties of MMC can be tailored using various ***,extensive research has been conducted on the AM of MMCs;however,the major huddle for this process has been the difficulties in preparing feedstock powder and operating the AM *** study introduces an easily synthesizable core-shell composite powder,which was fabricated by a recently developed process called the smart *** core-shell powder has a novel morphology,consisting of a metal core and composite shell,distinguishing it from the powders used in conventional AM *** 625/TiCp composites were fabricated using the core-shell composite powder,with various fractions of TiCp up to 10 vol.%.Compared to additive-manufactured Inconel 625,the additive-manufactured MMCs showed enhanced strength with significantly fewer *** results of this study may accelerate the application of MMC fabricated by AM,which offers superior properties and reliability compared to casting and powder metallurgy due to the higher degree of dislocation density and reinforcement dispersion.

关键词： Powder treatment Composite powder Metal matrix composite Additive manufacturing Nickel-based superalloy Directed energy deposition

Connection Between Damping Torque Analysis and Energy Flow Analysis in Damping Performance Evaluation for Electromechanical Oscillations in Power Systems

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 19-28页

作者： Yong Hu Siqi Bu Xin Zhang Chi Yung chung Hui Cai Department of Electrical Engineering and Research Institute for smart Energy The Hong Kong Polytechnic UniversityHong KongChina Shenzhen Research Institute The Hong Kong Polytechnic UniversityShenzhenChina Centre for Energy Systems and Strategy Cranfield UniversityCranfieldUK Department of Electrical and Computer Engineering University of SaskatchewanSaskatoonCanada State Grid Jiangsu Economic Research Institute NanjingChina

The damping performance evaluation for electromechanical oscillations in power systems is crucial for the stable operation of modern power *** this paper,the connection between two commonly-used damping performance evaluation methods,i.e.,the damping torque analysis(DTA)and energy flow analysis(EFA),are systematically examined and revealed for the better understanding of the oscillatory damping ***,a concept of the aggregated damping torque coefficient is proposed and derived based on DTA of multi-machine power systems,which can characterize the integration effect of the damping contribution from the whole power ***,the pre-processing of measurements at the terminal of a local generator is conducted for EFA,and a concept of the frequency-decomposed energy attenuation coefficient is defined to screen the damping contribution with respect to the interested *** this basis,the frequency spectrum analysis of the energy attenuation coefficient is employed to rigorously prove that the results of DTA and EFA are essentially equivalent,which is valid for arbitrary types of synchronous generator models in multi-machine power ***,the consistency between the aggregated damping torque coefficient and frequency-decomposed energy attenuation coefficient is further verified by the numerical calculation in case *** relationship between the proposed coefficients and the eigenvalue(or damping ratio)is finally revealed,which consolidates the application of the proposed concepts in the damping performance evaluation.

关键词： Electromechanical oscillation damping performance damping torque analysis(DTA) energy flow analysis(EFA) frequency spectrum

Synthesis and enhanced piezoelectric response of CVD-grown SnSe layered nanosheets for flexible nanogenerators

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Nano Research 2023年第9期16卷 11839-11845页

作者： Fumei Yang Man-chung Wong Jianfeng Mao Zehan Wu Jianhua Hao Department of Applied Physics the Hong Kong Polytechnic UniversityHong Kong 999077China

Piezoelectricity is the electric charge which accumulates in certain materials in response to mechanical stimuli,while piezoelectric nanogenerators(PENGs)converting mechanical energy into electricity can be widely used for energy harvesting and self-powered *** group IV-VI monochalcogenides may exhibit strong piezoelectricity because of their puckered C_(2v)symmetry and electronic structure,making them promising for flexible ***,we investigated the synthesis and piezoelectric properties of multilayer SnSe nanosheets grown by chemical vapor deposition(CVD).The SnSe nanosheets exhibited high single-crystallinity,large area,and good *** strong layer-dependent in-plane piezoelectric coefficient of SnSe nanosheets showed a saturated trend to be~110 pm/V,which overcomes the weak piezoelectric response or odd-even effects in other layered nanosheets.A high energy conversion efficiency of 9.3%and a maximum power density of 538 mW/cm^(2)at 1.03%strain have been demonstrated in a SnSe-based *** on the enhanced piezoelectricity of SnSe and attractive output performance of the nanogenerator,a self-powered sensor for human motion monitoring is further *** results demonstrate the strong piezoelectricity in high quality CVD-grown SnSe nanosheets,allowing for application in flexible smart piezoelectric sensors and advanced microelectromechanical devices.

关键词： SnSe piezotronics piezoresponse force microscope piezoelectric nanogenerator self-powered device

Environmentally adaptive reshaping of plant photomorphogenesis by karrikin and strigolactone signaling

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Journal of Integrative Plant Biology 2024年第5期66卷 865-882页

作者： Young-Joon Park Bo Eun Nam chung-Mo Park Department of smart Farm Science Kyung Hee UniversityYongin 17104Korea Departmentof Biological Sciences Seoul National UniversitySeoul 08826Korea Department of Chemistry Seoul National UniversitySeoul 08826Korea

Coordinated morphogenic adaptation of growing plants is critical for their survival and propagation under fluctuating *** morphogenic responses to light and warm temperatures,termed photomorphogenesis and thermomorphogenesis,respectively,have been extensively studied in recent *** photomorphogenesis,plants actively reshape their growth and developmental patterns to cope with changes in light ***,photomorphogenesis is closely associated with diverse growth hormonal ***,accumulating evidence indicates that light-directed morphogenesis is profoundly affected by two recently identified phytochemicals,karrikins(KARs)and strigolactones(SLs).KARs and SLs are structurally related butenolides acting as signaling molecules during a variety of developmental steps,including seed *** receptors and signaling mediators have been identified,and associated working mechanisms have been explored using gene-deficient mutants in various plant *** particular interest is that the KAR and SL signaling pathways play important roles in environmental responses,among which their linkages with photomorphogenesis are most comprehensively studied during seedling *** this review,we focus on how the phytochemical and light signals converge on the optimization of morphogenic *** also discuss molecular mechanisms underlying the signaling crosstalks with an aim of developing potential ways to improve crop productivity under climate changes.

关键词： karrikins morphogenic adaptation photomorphogenesis seedling establishment strigolactones

A Framework for Enhancing Privacy and Anonymity in Blockchain-Enabled IoT Devices

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Computers, Materials & Continua 2024年第3期78卷 4263-4282页

作者： Muhammad Saad Muhammad Raheel Bhutta Jongik Kim Tae-Sun chung Department of Artificial Intelligence Ajou UniversitySuwon443-749Korea Department of Electrical and Computer Engineering University of Utah Asia CampusIncheon21985Korea Department of Artificial Intelligence Chungnam National UniversityDaejeon34134Korea

With the increase in IoT(Internet of Things)devices comes an inherent challenge of *** the world today,privacy is the prime concern of every *** one’s privacy and keeping anonymity throughout the system is a desired functionality that does not come without inevitable trade-offs like scalability and increased complexity and is always exceedingly difficult to *** challenge is keeping confidentiality and continuing to make the person innominate throughout the *** address this,we present our proposed architecture where we manage IoT devices using blockchain *** proposed architecture works on and off blockchain integrated with the closed-circuit television(CCTV)security camera fixed at the rental *** this framework,the CCTV security camera feed is redirected towards the owner and renter based on the smart contract *** entity(owner or renter)can see the CCTV security camera feed at one *** is no third-party dependence except for the CCTV security camera deployment *** contributions include the proposition of framework architecture,a novel smart contract algorithm,and the modification to the ring signatures leveraging an existing cryptographic *** are made based on different systems’security and key management *** an empirical study,our proposed algorithm performed better in key generation,proof generation,and verification *** comparing similar existing schemes,we have shown the proposed architectures’*** now,we have developed this system for a specific area in the real ***,this system is scalable and applicable to other areas like healthcare monitoring systems,which is part of our future work.

关键词： Privacy anonymity blockchain IoT smart contracts