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Deposition processes and properties of coatings on steel fasteners——A review

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Friction 2019年第5期7卷 389-416页

作者： Ping Ping chung James WANG Yvonne DURANDET Department of Mechanical and Product Design Engineering Faculty of Science Engineering and Technology Swinburne University of Technology

Mechanical fastening is widely used in joining metals, particularly in automotive, aerospace, building and construction industries. However, the main concern on mechanical fastening is the issue of corrosion. An effective way to prolong the service life of steel fasteners is to apply protective coatings onto these components. This paper reviews and compares a few common coating deposition techniques, i.e., electroplating, hot-dip galvanizing, ion vapour deposition and mechanical plating, in terms of their characteristics. Compositional and microstructural properties including morphology and porosity, corrosion resistance performance and frictional performance of the coatings formed by each process are discussed in details. Hydrogen embrittlement, a premature failure often occurred on high strength steel fasteners, is also reviewed. The key results of recent studies of various metallic coatings on fasteners are presented to provide a fundamental understanding of the evolving topics, and the research gaps have been identified for further investigation.

关键词： zinc coating steel fasteners frictional characteristics corrosion performance mechanical plating electroplating

Efficient nonlinear companding scheme for substantial reduction in peak-to-average power ratio of OFDM

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Journal of Systems Engineering and Electronics 2015年第5期26卷 924-931页

作者： Kasun Bandara Atul Sewaiwar Yeon-Ho chung Department of Information and Communications Engineering Pukyong National University

Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding *** this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.

关键词： companding orthogonal frequency division multiplexing(OFDM) peak-to-average power ratio(PAPR)

Development of a group support system to support collaborative works in value management workshops

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Journal of Harbin Institute of Technology(New Series) 2004年第1期11卷 91-97页

作者： chung J K H Dept. of Building and Real Estate Hong Kong Polytechnic University Kowloon Hong Kong China

Value Management (VM) is a rigorous and systematic approach to improve the value and optimise the overall cost of a facility. It identifies opportunities to remove unnecessary costs while assuring that quality, reliability, performance, and other critical factors will meet or exceed the customers’ expectations. It has been widely used in the construction industry in a number of countries. A recent survey, however, revealed several problems that hinder the wider use of this methodology in the industry. To overcome these problems, a feasibility study has been conducted to investigate whether or not a Group Support System (GSS) can support collaborative works in VM workshops. This paper introduces the development and structure of a prototype GSS which is designed to support the collaborative works of stakeholders in VM workshops. It begins with an introduction to the conceptual GSS framework and job plan, illustrating what GSS supports can be provided to VM workshops. This is followed by a detailed description of the GSS prototype system to demonstrate how these supports can be performed as an integrated computer system. The testing of the system is also discussed. The research findings provide strong evidence in supporting the notion of using GSS to improve VM implementation. The information support of GSS has been ranked to be the most useful GSS functions and most of the practitioners interviewed are highly interested in applying GSS to support VM workshops in the future.

关键词： group support system value management workshops construction

Dual ultra-wideband(UWB)radar-based sleep posture recognition system:Towards ubiquitous sleep monitoring

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再生工程(英文) 2023年第1期4卷 36-43页

作者： Derek Ka-Hei Lai Li-Wen Zha Tommy Yau-Nam Leung Andy Yiu-Chau Tam Bryan pak-Hei So Hyo-Jung Lim Daphne Sze Ki Cheung Duo Wai-Chi Wong James chung-Wai Cheung Department of Biomedical Engineering Faculty of EngineeringThe Hong Kong Polytechnic UniversityHong Kong 999077China Department of Bioengineering Imperial CollegeLondon SW72AZUnited Kingdom Research Institute of Smart Ageing The Hong Kong Polytechnic UniversityHong KongChina School of Nursing The Hong Kong Polytechnic UniversityHong KongChina

Sleep posture monitoring is an essential assessment for obstructive sleep apnea(OSA)*** objective of this study is to develop a machine learning-based sleep posture recognition system using a dual ultra-wideband radar *** collected radiofrequency data from two radars positioned over and at the side of the bed for 16 patients performing four sleep postures(supine,left and right lateral,and prone).We proposed and evaluated deep learning approaches that streamlined feature extraction and classification,and the traditional machine learning approaches that involved different combinations of feature extractors and *** results showed that the dual radar system performed better than either single *** statistical features with random forest classifier yielded the best accuracy(0.887),which could be further improved via an ablation study(0.938).Deep learning approach using transformer yielded accuracy of 0.713.

关键词： Obstructive sleep apnea Deep learning Sleep monitoring Feature extraction Ablation study

Effects of dispersoid preforming via multistep sintering of oxide dispersion-strengthened CoCrFeMnNi high-entropy alloy

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Journal of Materials Science & Technology 2023年第9期140卷 187-200页

作者： SeungHyeok chung Ji Ho Shin Ho Jin Ryu Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Central Research Institute Korea Hydro and Nuclear Power Co.Ltd.(KHNP)Daejeon 34101Republic of Korea

Dispersoid formation and microstructural evolution in an oxide dispersion-strengthened CoCrFeMnNi high-entropy alloy(HEA)using a newly designed multistep sintering process are *** proposed multistep sintering consists of a dispersoid preforming heat treatment of as-milled 0.1 wt%Y_(2)O_(3)-CoCrFeMnNi high-entropy alloy powders at 800℃,followed by sintering at 800–1000℃ under uniaxial *** the conventional single-step sintered bulk,the coarsened BCC Y_(2)O_(3)dispersoids mainly form with an incoherent interface with the HEA *** contrast,finer FCC Y_(2)O_(3)dispersoids,an atypical form of Y_(2)O_(3),are formed in the matrix region after multistep *** of FCC Y_(2)O_(3)disper-soids is initiated on the favorable facet,the{111}plane of the austenitic matrix,with the formation of a semi-coherent interface with the matrix during the dispersoid preforming heat treatment and it maintains its refined size even after *** is found that dispersoid preforming prior to sintering appears promising to control the finer dispersoid formation and refined grain structure.

关键词： Oxide dispersion strengthening High-Entropy alloy Multistep sintering Dispersoid preforming Microstructure evolution Interfacial structure

Mortar DG Method with Staggered Hybridization for Rayleigh Waves Simulation

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Communications in Computational Physics 2021年第1期29卷 111-127页

作者： Jie Du Eric chung Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084P.R.China Department of Mathematics The Chinese University of Hong KongShatinNew TerritoriesHong Kong SARChina

The simulation of Rayleigh waves is important in a variety of geophysical *** computational challenge is the fact that very fine mesh is necessary as the waves are concentrated at the free surface and decay exponentially away from the free *** overcome this challenge and to develop a robust high order scheme for the simulation of Rayleigh waves,we develop a mortar discontinuous Galerkin method with staggered *** use of the mortar technique allows one to use fine mesh in only a local region near the free surface,and use coarse mesh in most of the *** approach reduces the computational cost *** staggered hybridization allows the preservation of the strong symmetry of the stress tensor without complicated construction of basis *** particular,the basis functions are piecewise polynomial without any continuity requirement,and the coupling of the basis functions is performed by using carefully chosen hybridized *** resulting scheme is explicit in time,and only local saddle point system are solved for each time *** will present several benchmark problems to demonstrate the performance of the proposed method.

关键词： Discontinuous Galerkin method elastic wave equations Rayleigh wave mortar for-mulation hybridization

简版中文五维度正念问卷在大学生和运动员群体中的结构效度检验

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中国运动医学杂志 2016年第1期35卷 53-62页

作者：钟伯光张春青姒刚彦刘靖东香港浸会大学体育学系香港教育学院健康与体育学系

本研究的目的是在香港大学生和中国运动员群体中检验中文版本的五维度正念问卷(Five Facet Mindfulness Questionnaire,FFMQ)及其简版的结构效度。研究共调查了417名香港大学生以及479名省队运动员。在不使用打包技术的情况下,探索结构... 详细信息

本研究的目的是在香港大学生和中国运动员群体中检验中文版本的五维度正念问卷(Five Facet Mindfulness Questionnaire,FFMQ)及其简版的结构效度。研究共调查了417名香港大学生以及479名省队运动员。在不使用打包技术的情况下,探索结构方程建模(ESEM)分析支持了中文版本的FFMQ的因素效度,并发展了一个20条目的简版五维度正念问卷(FFMQ-SF)。FFMQ-SF在大学生和运动员群体的内部一致性信度、重测信度、因素效度以及校标关联效度都达到了较为理想的标准。总之,39条目的完全版FFMQ以及20条目的 FFMQ-SF都可以作为评估中国香港大学生和中国运动员正念能力的一个有效和可靠的测量工具。

关键词：正念问卷运动员学生结构效度

Benefits of the Seattle biopsy protocol in the diagnosis of Barrett's esophagus in a Chinese population

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World Journal of Clinical Cases 2018年第14期6卷 753-758页

作者： Shou-Wu Lee Han-chung Lien Chi-Sen Chang Ming-Xian Lin chung-Hsin Chang chung-Wang Ko Division of Gastroenterology Department of Internal Medicine Taichung Veterans General Hospital Taichung 40705 Taiwan Department of Internal Medicine Chung Shan Medical University Taichung 40201 Taiwan Department of Internal Medicine National Yang-Ming University Taipei 11221 Taiwan

AIMTo investigate the benefits of the Seattle protocol in the diagnosis of Chinese individuals with Barrett’s *** enrolled were patients from one center with endoscopically-suspected esophageal metaplasia. These patients first received narrow-band imaging-targeted biopsy, and later, the Seattle protocol-guided biopsy, within a period from October 2012 to December 2014. Those cases without initial pathologic patterns of intestinal metaplasia （IM） and then appearance or loss of IM tissue were designated as Group A or B, respectively. Those with initial pathologic patterns ofIM, which then persisted or were lost were designated as Group C or D, *** number of cases for each group was as follows： A： 20, B： 78, C： 31 and D： 14. The distribution of the Prague criteria M levels of Group A was significantly higher than Group B （ P = 0.174）. Among these groups, Group C had the highest proportions of hiatus hernia （54.8%）, long segment Barrett’s esophagus （29%）, and also the highest Prague criteria M levels. The sensitivity of IM detection was 69.2% for the narrow-band imaging-targeted biopsy and 78.5% for the Lee SW et al . Seattle protocol for Barrett’s esophagusSeattle protocol-guided biopsy. The difference was not signifcant （P = 0.231）. The number of detectable dysplasias increased from one case via the NBI-target biopsy to five cases via the Seattle protocol-guided biopsy, including one case of *** Seattle protocol improved the IM detection in our subjects with higher Prague criteria M levels and disclosed more cases with dysplastic tissues.

关键词： Barrett’s esophagus Dysplasia Intestinal metaplasia Seattle protocol Chinese

Identical-video retrieval using the low-peak feature of a video's audio information

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第3期11卷 151-159页

作者： Myoung-beom chung Il-ju KO Department of Media Soongsil University

The recognition and retrieval of identical videos by combing through entire video files requires a great deal of time and memory space. Therefore, most current video-matching methods analyze only a part of each video's image frame information. All these methods, however, share the critical problem of erroneously categorizing identical videos as different if they have merely been altered in resolution or converted with a different codec. This paper deals instead with an identical-video-retrieval method using the low-peak feature of audio data. The low-peak feature remains relatively stable even with changes in bit-rate or codec. The proposed method showed a search success rate of 93.7% in a video matching experiment. This approach could provide a technique for recognizing identical content on video file share sites.

关键词： Video retrieval Video DNA Audio signal processing Audio feature extraction