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Modelling for registration of remotely sensed imagery when reference control points contain error

Science China Earth Sciences 2006年第7期49卷 739-746页

作者： leung Yee The Department of Geography and Resource Management The Chinese University of Hong Kong Shatin Hong Kong China

Reference control points (RCPs) used in establishing the regression model in the regis-tration or geometric correction of remote sensing images are generally assumed to be “perfect”. That is, the RCPs, as explanatory variables in the regression equation, are accurate and the coordinates of their locations have no errors. Thus ordinary least squares (OLS) estimator has been applied exten-sively to the registration or geometric correction of remotely sensed data. However, this assumption is often invalid in practice because RCPs always contain errors. Moreover, the errors are actually one of the main sources which lower the accuracy of geometric correction of an uncorrected image. Under this situation, the OLS estimator is biased. It cannot handle explanatory variables with errors and cannot propagate appropriately errors from the RCPs to the corrected image. Therefore, it is essential to develop new feasible methods to overcome such a problem. This paper introduces a consistent adjusted least squares (CALS) estimator and proposes relaxed consistent adjusted least squares (RCALS) estimator, with the latter being more general and flexible, for geometric correction or regis-tration. These estimators have good capability in correcting errors contained in the RCPs, and in propagating appropriately errors of the RCPs to the corrected image with and without prior information. The objective of the CALS and proposed RCALS estimators is to improve the accuracy of measure-ment value by weakening the measurement errors. The conceptual arguments are substantiated by a real remotely sensed data. Compared to the OLS estimator, the CALS and RCALS estimators give a superior overall performance in estimating the regression coefficients and variance of measurement errors.

关键词： error modelling, registration, ordinary least squares, relaxed consistent adjusted least squares, remote sensing images.

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Effects of Risk Perception on Disaster Preparedness Toward Typhoons:An Application of the Extended Theory of Planned Behavior

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International Journal of Disaster Risk Science 2022年第1期13卷 100-113页

作者： Sai leung Ng Graduate Institute of Earth Science Chinese Culture UniversityTaipei 11114TaiwanChina

This study adopted an extended theory of planned behavior to understand how risk perception affected disaster preparedness *** intercept survey(N=286)was conducted at a typhoon-prone district of Hong Kong,China in 2019,then the data were analyzed using structural equation *** results indicated that risk perception and intention of preparedness were predictors of disaster preparedness *** perception significantly affected intention of preparedness and the effect was partially mediated by subjective *** perception also significantly affected attitude and perceived behavioral control,but attitude and perceived behavioral control were not significantly correlated with intention of *** only may this study supplement the existing literature of disaster preparedness toward typhoons,but also it provides insights for the planning and management of natural hazards and disaster risk reduction in Hong Kong,China.

关键词： Disaster preparedness behaviour Hong Kong,China Risk perception Structural equation modelling Theory of planned behaviour Typhoon preparedness

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Treatment of pediatric refractory Crohn’s disease with thalidomide

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World Journal of Gastroenterology 2011年第10期17卷 1286-1291页

作者： Ying-Kit leung Department of Gastroenterology Children’s Hospital of Fudan University

AIM: To assess the efficacy and tolerability of thalidomide in pediatric Crohn's disease (CD). METHODS: Six patients with refractory CD received thalidomide at an initial dose of 2 mg/kg per day for one month, then increased to 3 mg/kg per day or decreased to 1 mg/kg per day, and again further reduced to 0.5 mg/kg per day, according to the individual patient's response to the drug. RESULTS: Remission was achieved within three months. Dramatic clinical improvement was demonstrated after thalidomide treatment. Endoscopic and pathological improvements were also observed after thalidomide treatment, which was well tolerated by all patients. CONCLUSION: Thalidomide is a useful drug for pediatric refractory CD.

关键词： Inflammatory bowel disease Thalidomide Tumor necrosis factor-m Children

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Differentially weighted operator splitting Monte Carlo method for simulating complex aerosol dynamic processes

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Particuology 2018年第1期16卷 114-126页

作者： Hongmei Liu Tat leung Chan Department of Mechanical Engineering The Hong Kong Polytechnic University Kowloon Hong Kong China

A differentially weighted operator splitting Monte Carlo （DWOSMC） method is developed to solve com- plex aerosol dynamic processes by coupling the differentially weighted Monte Carlo method and the operator splitting technique. This method is validated by analytical solutions and a sectional method in different aerosol dynamic processes. It is first validated in coagulation and condensation processes, and nucleation and coagulation processes, and then validated through simultaneous nucleation, coagulation, and condensation processes. The results show that the DWOSMC method is a computationally efficient and quantitatively accurate method for simulating complex aerosol dynamic processes.

关键词： Differentially weighted Monte Carlo Operator splitting Aerosol dynamics Particle size distribution

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Evaluation and management of the child with hypothyroidism

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World Journal of Pediatrics 2019年第2期15卷 124-134页

作者： Alexander K.C.leung Alexander A.C.leung Department of Pediatrics The University of Calgaryand The Alberta Children's Hospital#200233-16th Avenue NWCalgaryAB T2M 0H5Canada Department of Medicine The University of CalgaryCalgaryABCanada

Background Thyroid hormones are critical for early neurocognitive development as well as growth and development throughout *** recognition and treatment of hypothyroidism is,therefore,of utmost importance to optimize physical and neurodevelopmental *** sources A PubMed search was completed in Clinical Queries using the key terms 'hypothyroidism'.Results Hypothyroidism may be present at birth (congenital hypothyroidism) or develop later in life (acquired hypothyroidism).Thyroid dysgenesis and dyshormonogenesis account for approximately 85% and 15% of permanent cases of congenital primary hypothyroidism,*** than 95% of infants with congenital hypothyroidism have few,if any,clinical manifestations of *** screening programs allow early detection of congenital *** developed countries,Hashimoto thyroiditis is the most common cause of goiter and acquired hypothyroidism in children and ***,iodine deficiency associated with goiter is the most common cause of *** hypothyroidism is uncommon and may be associated with other congenital syndromes and deficiencies of other pituitary *** of the clinical features would allow prompt diagnosis and institution of *** To optimize neurocognitive outcome in infants with congenital hypothyroidism,treatment with levothyroxine should be started as soon as possible,preferably within the first 2 weeks of *** with acquired hypothyroidism should also be treated early to ensure normal growth and development as well as cognitive *** target is to keep serum TSH < 5 mIU/L and to maintain serum free T4 or total T4 within the upper half of the age-specific reference range,with elimination of all symptoms and signs of hypothyroidism.

关键词： Dysgenesis Dyshormonogenesis Hashimoto thyroiditis Hypothyroidism Iodine deficiency Levothyroxine Mental retardation Stunted growth

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An in-depth investigation into the relationships between structural metrics and unit testability in object-oriented systems

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Science China(Information Sciences) 2012年第12期55卷 2800-2815页

作者： leung Hareton Department of Computing Hong Kong Polytechnic University

There is a common belief that structural properties of classes are important factors to determine their unit ***,few empirical studies have been conducted to examine the actual impact of structural properties of *** this paper,we employ multiple linear regression(MLR) and partial least square regression(PLSR) to investigate the relationships between the metrics measuring structural properties and unit testability of a *** investigated structural metrics cover five property dimensions,including size,cohesion,coupling,inheritance,and *** results from open-source software systems show that:(1) most structural metrics are statistically related to unit testability in an expected direction,among which size,complexity,and coupling metrics are the most important predictors;that(2) multivariate regression models based on structural metrics cannot accurately predict unit testability of classes,although they are better able to rank unit testability of classes;that(3) the transition from MLR to PLSR could significantly improve the ability to rank unit testability of classes but cannot improve the ability to predict the unit testing effort of classes.

关键词： testability metrics object-oriented testing effort unit testing prediction

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Coordination and nursing care of pediatric patients undergoing double balloon enteroscopy

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World Journal of Gastroenterology 2011年第25期17卷 3049-3053页

作者： Ying-Kit leung Department of Gastroenterology Children's Hospital of Fudan University

AIM:To review safety,efficacy,and proper nursing care of double-balloon enteroscopy (DBE) in pediatric patients with small intestinal ***:Our study included 37 patients with abdominal pain,diarrhea,passage of blood in the stools,and other symptoms,who underwent DBE from December 2006 to July *** was retrograde in 36 procedures,antegrade in six,and from both ends in *** diagnostic significance and salient points in nursing care are discussed in this ***:At least one lesion was discovered in 28 out of 37 patients,which yielded a positive diagnosis in 75.7% of *** bowel preparation and skilled nursing care not only shortened the procedure time,but could also alleviate patient discomfort and enhance the quality of *** serious procedure-related complications were observed in any ***:DBE is a new modality of endoscopic procedure that improves the standard of diagnosis and treatment of small bowel diseases in *** nursing care is essential to the successful execution of the procedure.

关键词： Children Double-balloon enteroscopy Nurs-ing care Small intestinal disease

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DYNAMIC RESOURCE ALLOCATION FOR EFFICIENT PATIENT SCHEDULING： A DATA-DRIVEN APPROACH

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Journal of Systems Science and Systems Engineering 2017年第4期26卷 448-462页

作者： Monique Bakker Kwok-leung Tsui Department of Systems Engineering and Engineering Management City University of Hong Kong China

Efficient staff rostering and patient scheduling to meet outpatient demand is a very complex and dynamic task. Due to fluctuations in demand and specialist availability, specialist allocation must be very flexible and non-myopic. Medical specialists are typically restricted in sub-specialization, serve several patient groups and are the key resource in a chain of patient visits to the clinic and operating room （OR）. To overcome a myopic view of once-off appointment scheduling, we address the patient flow through a chain of patient appointments when allocating key resources to different patient groups. We present a new, data-driven algorithmic approach to automatic allocation of specialists to roster activities and patient groups. By their very nature, simplified mathematical models cannot capture the complexity that is characteristic to the system being modeled. In our approach, the allocation of specialists to their day-to-day activities is flexible and responsive to past and present key resource availability, as well as to past resource allocation. Variability in roster activities is actively minimized, in order to enhance the supply chain flow. With discrete-event simulation of the application case using empirical data, we illustrate how our approach improves patient Service Level （SL, percentage of patients served on-time） as well as Wait Time （days）, without change in resource capacity.

关键词： Patient scheduling dynamic rostering patient care path discrete-event simulation

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(-)Epicatechin induces and modulates endothelium-dependent relaxation in isolated rat mesenteric artery rings

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Acta Pharmacologica Sinica 2002年第12期23卷 135-139页

作者： CHAN Franky leung China Chinese University of Hong Kong Department of Anatomy

AIM: The present study was aimed to examine the role of endothelial nitric oxide in the relaxant response to green tea (-)epicatechin and its modulation of endothelium-mediated relaxation in the isolated rat mesenteric artery rings. METHODS: Changes in the isometric tension were measured with Grass force-displacement transducers. RESULTS: The (-)epicatechin-induced relaxation was largely dependent on the presence of intact endothelium and was re-versed by NG-nitro-L-arginine methyl ester 10 μmol/L or methylene blue 10 μmol/L, the inhibitors of nitric oxide-mediated relaxation. L-Arginine at 1 mmol/L antagonized the effect of L-NAME or methylene blue. Pretreatment of endothelium-intact rings with (-)epicatechin 10 μmol/L enhanced the relaxation induced by endothelium-dependent vasodilator, acetylcholine, while this concentration did not influence the endothelium-independent relaxation in-duced by sodium nitroprusside in the endothelium-denuded artery rings. CONCLUSION: The results indicate that the en

关键词： (-)epicatechin vascular endothelium nitric oxide muscle relaxation mesenteric artery rats

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Study on the wind field and pollutant dispersion in street canyons using a stable numerical method

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Journal of Environmental Sciences 2005年第3期17卷 488-490页

作者： Dennis Y.C. leung Department of Mechanical Engineering the University of Hong Kong Hong Kong China

A stable finite element method for the time dependent Navier-Stokes equations was used for studying the wind flow and pollutant dispersion within street canyons. A three-step fractional method was used to solve the velocity field and the pressure field separately from the governing equations. The Streamline Upwind Petrov-Galerkin(SUPG) method was used to get stable numerical results. Numerical oscillation was minimized and satisfactory results can be obtained for flows at high Reynolds numbers. Simulating the flow over a square cylinder within a wide range of Reynolds numbers validates the wind field model. The Strouhal numbers obtained from the numerical simulation had a good agreement with those obtained from experiment. The wind field model developed in the present study is applied to simulate more complex flow phenomena in street canyons with two different building configurations. The results indicated that the flow at rooftop of buildings might not be assumed parallel to the ground as some numerical modelers did. A counter-clockwise rotating vortex may be found in street canyons with an inflow from the left to right. In addition, increasing building height can increase velocity fluctuations in the street canyon under certain circumstances, which facilitate pollutant dispersion. At high Reynolds numbers, the flow regimes in street canyons do not change with inflow velocity.

关键词： finite element method Streamline Upwind Petrov-Galerkin method three-step fractional method

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