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Energy performance analysis of multi-chiller cooling systems for data centers concerning progressive loading throughout the lifecycle under typical climates

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Building Simulation 2024年第10期17卷 1693-1708页

作者： Yingbo Zhang Hangxin Li Shengwei Wang Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Research institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

The increasing demand for cooling energy in data centers has become a global *** studies lack a comprehensive analysis of the energy performance of widely used multi-chiller cooling systems in air-cooled data centers throughout their lifecycle,especially concerning progressive *** bridge this gap,this study conducts a thorough assessment of the energy performance of multi-chiller cooling systems throughout the entire ***,the impact of climate conditions on the energy efficiency of the cooling systems is analyzed,considering design variations for typical ***-chiller cooling system models are developed using the test data of cooling equipment and typical control *** energy performance of the cooling system is thoroughly analyzed under full-range cooling loads and climate *** show that free cooling time could differ up to 1442 hours at different part load ratios in the same ***,the cooling system’s coefficient of performance(COP)varies significantly,by up to 6,at different part load ratios,corresponding to a difference in power usage effectiveness(PUE)up to ***,the average cooling system COP throughout the lifecycle loading is found to be only 11.7,2.9 lower than the design system COP.

关键词： data center cooling system energy performance life-cycle operation power usage effectiveness(PUE) coefficient of performance(COP)

A gigaparsec-scale local void and the Hubble tension

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Science China(Physics,Mechanics & Astronomy) 2020年第9期63卷 7-15页

作者： QianHang Ding Tomohiro Nakama Yi Wang Department of Physics The Hong Kong University of Science and TechnologyHong KongChina Jockey Club institute for Advanced Study The Hong Kong University of Science and TechnologyHong KongChina

We explore the possibility of using a gigaparsec-scale local void to reconcile the Hubble *** a gigaparsec-scale void can be produced by multi-stream inflation where different parts of the observable universe follow different inflationary *** trajectories become different parts of the observable universe after inflation,when these scales return to the *** these trajectories have different e-folding numbers,these parts of the universe have different energy densities,possibly creating a local large *** impacts of such a void for cosmological observations are studied,especially those involving supernovae,Baryon Acoustic Oscillations(BAO)and the kinetic Sunyaev-Zel’dovich(kSZ)*** show that with the presence of the void,supernovae observations may be more consistent with the *** also estimate the impacts of a local large void on BAO *** addition,we show that a local large void and hence its capabilities to ease the Hubble tension is limited by the kSZ *** a benchmark model,a 1.7 Gpc scale void with boundary width 0.7 Gpc and density contrast-0.14 may ease the Hubble tension,evading the kSZ limit.

关键词： Hubble tension void cosmology inflation

SHAPE MEMORY EFFECT OF PU IONOMERS WITH IONIC GROUPS ON HARD-SEGMENTS

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Chinese Journal of Polymer Science 2006年第2期24卷 173-186页

作者：胡金莲 Kwok-wing Yeung institute of Textiles and Clothing hong kong Polytechnic University Hung HomHong KongChina

SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone）（PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） were measured with cyclic tensile test and strain recovery test. The relations between the structure and shape memory effect of these two series were studied with respect to the ionic group content and the effect of neutralization. The resulting data indicate that, with the introduction of asymmetrical extender, the stress at 100% elongation is decreased for PU non-ionomer and ionomer series, especially lowered sharply for non-ionomer series; the fixation ratio of ionomer series is not affected obviously by the ionic group content; the total recovery ratio of ionomer series is decreased greatly. After sufficient relaxation time for samples stretched beforehand, the switching temperature is raised slightly, whereas the recovery ratio measured with strain recovery test method is lowered with increased DMPA content. The characterization with FT-IR, DSC, DMA elucidated that, the ordered hard domain of the two series is disrupted with the introduction of DMPA which causes more hard segments to dissolve in soft phase; ionic groups on hard segment enhance the cohesion between hard segments especially at high ionic group content and significantly facilitate the phase separation compared with the corresponding non-ionomer at moderate ionic group content.

关键词： Polyurethane Ionomers Cyclic thermo-mechanical investigations Shape memory effect Cyclic tensile test Strain recovery test.

Antralization at the edge of proximal gastric ulcers:Does Helicobacter pylori infection play a role?

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World Journal of Gastroenterology 2003年第6期9卷 1265-1269页

作者： Harry Hua-Xinag Xia Shiu Kum Lam Wai Man Wong Wayne Hsing Cheng Hu Kam Chuen Lai Sau Hing Wong Suet Yi Leung Siu Tsan Yuen Nicholas A.Wright Benjamin Chun-Yu Wong Department of medicine The University of Hong KongHong Kong SARChina Department of Pathology The University of Hong KongHong Kong SARChina Histopathology Unit London Research InstituteCancer ResearchUK

AIM: To determine the prevalence of antralization at the edge of proximal gastric ulcers, and the effect ofH. pylori eradication on the mucosal appearances.METHODS: Biopsies were taken from the antrum, body and the ulcer edge of patients with benign proximal gastric ulcers before and one year after treatment. Gastric mucosa was classified as antral, transitional or body type.H. pylori positive patients receivedeither triple therapy, or omeprazole.RESULTS: Patients with index ulcers in the incisura, body or fundus (n=116) were analyzed. Antral-type mucosa was more prevalent at the ulcer edge inH. pylori-positive patients ***-negative patients (93% vs 60%, OR=8.95,95%CI: 2.47-32.4, P=0.001). At one year, there was a significant reduction in the prevalence of antralization (from 93 % to 61%, P=0.004) at the ulcer edge in patients with H. pyloribeing eradicated. However, there was no difference in the prevalence of antralization at the ulcer edge in those with persistent infection.CONCLUSION: H. pylori infection is associated with antralization at the edge of proximal gastric ulcers, which may be reversible in some patients after eradication of the infection.

关键词：胃溃疡幽门螺杆菌感染胃粘膜活组织检查

Place-and Age-Responsive Disaster Risk Reduction for hong kong:Collaborative Place Audit and Social Vulnerability Index for Elders

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International Journal of Disaster Risk Science 2017年第2期8卷 121-133页

作者： Yi Sun Pui Hing Chau Moses Wong Jean Woo CUHK Jockey Club institute of Ageing The Chinese University of Hong Kong Department of Building and Real Estate The Hong Kong Polytechnic University School of Nursing The University of Hong Kong Department of medicine and Therapeutics The Chinese University of Hong Kong

This study reformulates the concept and contents of disaster risk reduction(DRR) in hong kong through an explorative study on collaborative place audit(CPA) and social vulnerability index(SVI) for *** believe that DRR should be place-and ***,DRR needs to go beyond technical concerns and address vulnerability and risk encountered in the built environment where an individual is located.A place-centered DRR begins with an assessment of person–environment relations from an interdependent *** becomes a significant scale at which to address vulnerability and risks across a range of environmental,socioeconomic,and institutional factors.A CPA is a ground-level assessment tool that identifies vulnerability and risk in the built and social *** audit encourages collaboration in problem solving that uses social capital to effect decisionmaking change in hierarchies and policy *** DRR facilitates distinguishing living-alone elders from the general *** perspective addresses varying degrees of vulnerability due to social and communicational isolation,poverty,disability,being sent to hospital and/or receiving institutional care,as well as lack of access to primary ***,SVI,based oncompound indicators,is developed to assess the differentiation of vulnerability across the territory with particular reference to the *** two approaches,namely,CPA and SVI,build community capacity to develop a resilient city,as well as to provide evidence-based recommendations that improve government-led disaster preparedness and contingency plans.

关键词： Disaster risk reduction hong kong Place audit Social capital Social vulnerability

Artificial intelligence in gastroenterology:where are we heading?

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Frontiers of medicine 2020年第4期14卷 511-517页

作者： Joseph JY Sung Nicholas CH Poon institute of Digestive Disease Faculty of MedicineThe Chinese University of Hong KongHong KongChina Big Data Decision Analytic Cancer The Chinese University of Hong KongHong KongChina

Artificial intelligence(AI)is coming to medicine in a big *** making diagnosis in various medical conditions,following the latest advancements in scientific literature,suggesting appropriate therapies,to predicting prognosis and outcome of diseases and conditions,AI is offering unprecedented possibilities to improve care for *** is a field that AI can make a significant *** is partly because the diagnosis of gastrointestinal conditions relies a lot on image-based investigations and procedures(endoscopy and radiology).AI-assisted image analysis can make accurate assessment and provide more information than conventional *** integration of genomic,epigenetic,and metagenomic data may offer new classifications of gastrointestinal cancers and suggest optimal personalized *** managing relapsing and remitting diseases such as inflammatory bowel disease,irritable bowel syndrome,and peptic ulcer bleeding,convoluted neural network may formulate models to predict disease outcome,enhancing treatment *** and surgical robots can also assist surgeons in conducting gastrointestinal *** the advancement and new opportunities are exciting,the responsibility and liability issues of AI-assisted diagnosis and management need much deliberations.

关键词： artificial intelligence endoscopy robotics gastrointestinal diseases

Simultaneously improving mechanical properties and oxidation resistance of Ti-bearing high-entropy superalloys at intermediate temperature via silicon addition

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Journal of Materials Science & Technology 2023年第26期157卷 30-41页

作者： Shaofei Liu Weicheng Xiao Bo Xiao Jiang Ju Yinghao Zhou Yilu Zhao Zengbao Jiao Junhua Luan Qian Li Jinxiong Hou Ji-jung Kai Tao Yang Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Center for Advanced Nuclear Safety and Sustainable Development City University of Hong KongHong Kong 999077China Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China School of Materials Science and Engineering Harbin Institute of TechnologyShenzhen 518055China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China hong kong institute for Advanced Study City University of Hong KongHong Kong 999077China

Ti-bearing high-entropy superalloys(HESAs)often suffer from severe intergranular embrittlement and terrible oxidation degradation at intermediate *** we showcase that minor Si addition can effectively mitigate the intergranular embrittlement and improve the oxidation resistance of the a(Ni_(2)Co_(2)FeCr)_(92) Ti_(4)Al_(4) HESA at 700℃ *** analysis revealed that the intergranu-lar G phase induced by 2 at%Si addition can effectively suppress the inward diffusion of oxygen along grain boundaries at 700℃,thus enhancing the tensile ductility of the alloy from∼8.3%to∼13.4%.Be-sides,the 2 at%Si addition facilitated the formation of a continuous Al_(2)O_(3) layer during oxidation,con-tributing to a remarkable reduction in the growth rate of the oxide scale to a quarter of the Si-free *** results demonstrate that Si can be a favorable alloying element to design advanced HESAs with syn-ergistically improved thermal-mechanical performance.

关键词： High-entropy superalloy Mechanical property Oxidation behavior Intermediate temperature Silicon addition

A Simple and Efficient Algorithm to Identify the Chirality of Polymer Knots Based on the Alexander Polynomial

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Chinese Journal of Polymer Science 2024年第12期42卷 2030-2037,I0012页

作者： Qi-Yuan Qiu Yong-Jian Zhu Zhong-Tao Wu Liang Dai Department of Physics City University of Hong KongHong Kong999077China Shenzhen Research institute City University of Hong KongShenzhen518057China Department of Mathematics The Chinese University of Hong KongHong Kong999077China

Recent experimental observations of knotting in DNA and proteins have stimulated the simulation studies of polymer *** studies usually identify knots in polymer conformations through the calculation of the Alexander ***,the Alexander polynomial cannot directly discriminate knot chirality,while knot chirality plays important roles in many physical,chemical,and biological *** this work,we discover a new relationship for knot chirality and accordingly,develop a new algorithm to extend the applicability of the Alexander polynomial to the identification of knot *** algorithm adds an extra step in the ordinary calculation of the Alexander *** extra step only slightly increases the computational *** correctness of our algorithm has been proved mathematically by *** implication of this algorithm in physical research has been demonstrated by our studies of the tube model for polymer *** this algorithm,we would be unable to obtain the tubes for polymer knots.

关键词： Polymerentanglement Polymer knot Polymerconformation Tubemodel Monte Carlo simulation

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Happy Aging

Chinese Journal of integrative medicine 2009年第6期15卷 466-469页

作者：梁秉中 institute of Chinese medicine the Chinese University of Hong Kong

Aging is a normal physiological process in human *** decline in the ability to repair and regenerate predisposes the aging person to develop disabling problems in the cardiovascular and skeletal *** awareness of aging problems and advocations on the means to prevent their occurrence are *** and US groups rely on scientific,target-oriented means to treat aging manifestations. Oriental medicine aims at prevention,using nutrition and exercise to maintain internal harmony.

关键词： aging nutrition Chinese medicine