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A novel non-invasive model to predict high-risk varices in cirrhotic patients

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Hepatobiliary Surgery and Nutrition 2024年第3期13卷 530-532页

作者： kelvin k.C.ng Department of Surgery The Chinese University of Hong Kong Medical CentreHong KongChina

Acute variceal bleeding is one of the most common and potentially life-threatening complications in patients with liver *** is conventionally diagnosed by oesophagogastroduodenoscopy,which is invasive to patients and carries hospital *** would be more cost-effective if non-invasive tests could screen out high-risk patients who developed acute variceal bleeding requiring endoscopic *** can potentially reduce the need for invasive procedures for cirrhotic *** recent years,there have been advancements in non-invasive methods for assessing the risk of variceal *** include transient elastography(FibroScan)of the liver and spleen,platelet count,imaging modalities[ultrasound or magnetic resonance imaging(MRI)],and non-invasive liver function tests[Child-Pugh score or the Model for End-Stage Liver Disease(MELD)score].The 2015 Baveno VI consensus is developed by an international panel of experts to improve the diagnosis and management of portal hypertension and its complications,specifically focusing on variceal bleeding in patients with cirrhosis(1).The consensus emphasizes using noninvasive methods to screen out high-risk varices(HRV)requiring therapeutic *** key features of the Baveno VI criteria include a liver stiffness measurement(LSM)kPa and a platelet count>150,000/*** can confidently rule out *** has been proven to avoid unnecessary endoscopy up to 40%with a specificity of up to 46%(2).In recent years,spleen stiffness measurement(SSM)has been a useful tool to assess portal hypertension and to predict ***,the revised Baveno VII consensus in 2022 recommends SSM≤40 kPa would avoid more unnecessary endoscopy in patients who fall outside Baveno VI criteria,with a missed HRV rate of<5%(3).

关键词： Non-invasive model high-risk varices cirrhosis

Single-pilot operations in commercial flight:Effects on neural activity and visual behaviour under abnormalities and emergencies

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Chinese Journal of Aeronautics 2024年第8期37卷 277-292页

作者： Qinbiao LI Chun-Hsien CHEN kam k.H.ng Xin YUAN Cho Yin YIU Human Factors and Ergonomics Laboratory Department of Aeronautical and Aviation EngineeringThe Hong Kong Polytechnic UniversityHong Kong Special Administrative Region 100872China School of Mechanical&Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically *** changes in captains’natural behaviours are initially required to comprehend the specific safe human performance envelope for safeguarding single-pilot flight,particularly in high-risk *** paper investigates how captains’performance transforms for fixing emergencies when operating from Dual-Pilot Operations(DPO)to Single-Pilot Operations(SPO)through a physiological-based *** pilots flew an emergency-included flight with/without first officers’*** neural activities and scanning behaviours were recorded using a 32-channel Electroencephalogram(EEG)and glasses-based eye tracker,with the observation and post-experiment questionnaires to evaluate the flight operations and pilots’*** alone,there was a significantly increased cortical activity in h and b waves over the frontal,parietal,and temporal lobes during the more complicated emergencies,and pilots focused less on the primary flight display while spending significantly more time scanning the other *** physiological fluctuating patterns associated with risky operations in SPO were highlighted by cross-correlating multimodal *** experimental-based noteworthy insights may wish to inform commercial SPO measures to lessen the persistent physiological fluctuation,assisting airlines in creating SPO-oriented intelligent flight systems to give captains adequate support for assuring safer air transportation.

关键词： Aviation engineering Single pilot operations Behaviour changes Eye tracker Electroencephalogram

Preconditioned Iterative Methods for Algebraic Systems from Multiplicative Half-Quadratic Regularization Image Restorations

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Numerical Mathematics(Theory,Methods and Applications) 2010年第4期3卷 461-474页

作者： Michael k.ng Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

Image restoration is often solved by minimizing an energy function consisting of a data-fidelity term and a regularization term.A regularized convex term can usually preserve the image edges well in the restored *** this paper,we consider a class of convex and edge-preserving regularization functions,i.e.,multiplicative half-quadratic regularizations,and we use the Newton method to solve the correspondingly reduced systems of nonlinear *** each Newton iterate,the preconditioned conjugate gradient method,incorporated with a constraint preconditioner,is employed to solve the structured Newton equation that has a symmetric positive definite coefficient matrix. The eigenvalue bounds of the preconditioned matrix are deliberately derived,which can be used to estimate the convergence speed of the preconditioned conjugate gradient *** use experimental results to demonstrate that this new approach is efficient, and the effect of image restoration is reasonably well.

关键词： Edge-preserving image restoration multiplicative half-quadratic regularization Newton method preconditioned conjugate gradient method constraint preconditioner eigenvalue bounds

Compression of Battery X-Ray Tomography Data with Machine Learning

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Chinese Physics Letters 2024年第9期41卷 153-158页

作者： Zipei Yan Qiyu Wang Xiqian Yu Jizhou Li Michael k.-P.ng Department of Electronic Engineering The Chinese University of Hong KongHong KongChina Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China Huairou Division Institute of PhysicsChinese Academy of SciencesBeijing 101400China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China CUHk Shenzhen Research Institute Shenzhen 518057China Department of Mathematics Hong Kong Baptist UniversityHong KongChina

With the increasing demand for high-resolution x-ray tomography in battery characterization,the challenges of storing,transmitting,and analyzing substantial imaging data necessitate more efficient *** data compression methods struggle to balance reduction ratio and image quality,often failing to preserve critical details for accurate *** study proposes a machine learning-assisted compression method tailored for battery x-ray imaging *** physics-informed representation learning,our approach significantly reduces file sizes without sacrificing meaningful *** validate the method on typical battery materials and different x-ray imaging techniques,demonstrating its effectiveness in preserving structural and chemical *** results show an up-to-95 compression ratio while maintaining high fidelity in the projection and reconstructed *** proposed framework provides a promising solution for managing large-scale battery x-ray imaging datasets,facilitating significant advancements in battery research and development.

关键词： battery Battery details

ON ALGORITHMS FOR AUTOMATIC DEBLURRIng FROM A SIngLE IMAGE

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Journal of Computational Mathematics 2012年第1期30卷 80-100页

作者： Wei Wang Michael k.ng Department of Mathematics Tongji UniversityShanghai 200092China Centre for Mathematical Imaging and Vision and Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong KongChina

In this paper, we study two variational blind deblurring models for a single linage,The first model is to use the total variation prior in both image and blur, while the second model is to use the flame based prior in both image and blur. The main contribution of this paper is to show how to employ the generalized cross validation （GCV） method efficiently and automatically to estimate the two regularization parameters associated with the priors in these two blind motion deblurring models. Our experimental results show that the visual quality of restored images by the proposed method is very good, and they are competitive with the tested existing methods. We will also demonstrate the proposed method is also very efficient.

关键词： Blind deconvolution Iterative methods Total variation Framelet Generalizedcross validation.

Three-year field study on grass growth and soil hydrological properties in biochar-amended soil

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2764-2774页

作者： Haowen Guo Charles Wang Wai ng Junjun Ni Qi Zhang Yuchen Wang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina School of Transportation Southeast UniversityNanjingChina

Field monitoring was conducted to investigate and quantify the long-term effects of peanut shell biochar on soil-grass interaction over three *** 10 m5 m grassed plots were constructed in completely decomposed granitic *** of them were amended,respectively,with 5%and 10%biochar contents(m^(3)/m^(3))for grass growth,while the third was without biochar *** the threeyear monitoring,plant characteristics,saturated water permeability(k_(s))of grassed soil and soil suction were *** monitored results show that the grass leaf area index(LAI)and root length density(RLD)with biochar amendment were improved by 38%and 200%,*** the grassed plot without biochar,a threshold RLD existed with a value of 1.7 cm/cm^(3),beyond which k_(s) raised *** threshold RLD increased by 52%when biochar content increased from 0%to 10%.This implies that biochar may restrict the increase in k_(s) of grassed soil due to the rise in the threshold *** presence of biochar and grass can retain over 100%higher suction after heavy rainfalls,while 54%lower peak suction under evapotranspiration(ET)compared with the non-amended *** can alleviate the negative effects on hydraulic properties caused by plant growth and reduce ET-induced excessive water loss.A 5%peanut shell biochar content is recommended for the long-term management of vegetated earthen infrastructures.

关键词： Soil-grass interaction Biochar Long-term Water infiltration Soil drying

A Nonlocal Total Variation Model for Image Decomposition: Illumination and Reflectance

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Numerical Mathematics(Theory,Methods and Applications) 2014年第3期7卷 334-355页

作者： Wei Wang Michael k.ng Department of Mathematics Tongji UniversityShanghaiChina Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

In this paper,we study to use nonlocal bounded variation(NLBV)techniques to decompose an image intensity into the illumination and reflectance *** considering spatial smoothness of the illumination component and nonlocal total variation(NLTV)of the reflectance component in the decomposition framework,an energy functional is *** establish the theoretical results of the space of NLBV functions such as lower semicontinuity,approximation and *** essential properties of NLBV functions are important tools to show the existence of solution of the proposed energy *** results on both grey-level and color images are shown to illustrate the usefulness of the nonlocal total variation image decomposition model,and demonstrate the performance of the proposed method is better than the other testing methods.

关键词： Image decomposition illumination reflectance nonlocal total variation iterative method

kernel Density Estimation Based Multiphase Fuzzy Region Competition Method for Texture Image Segmentation

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Communications in Computational Physics 2010年第8期8卷 623-641页

作者： Fang Li Michael k.ng Department of Mathematics East China Normal UniversityShanghai 200241China Centre for Mathematical Imaging and Vision and Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

In this paper,we propose a multiphase fuzzy region competition model for texture image *** the functional,each region is represented by a fuzzy membership function and a probability density function that is estimated by a nonparametric kernel density *** overall algorithm is very efficient as both the fuzzy membership function and the probability density function can be implemented *** apply the proposed method to synthetic and natural texture images,and synthetic aperture radar *** experimental results have shown that the proposed method is competitive with the other state-of-the-art segmentation methods.

关键词： Texture multiphase region competition kernel density estimation fuzzy membership function total variation

Parallel Active Subspace Decomposition for Tensor Robust Principal Component Analysis

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Communications on Applied Mathematics and Computation 2021年第2期3卷 221-241页

作者： Michael k.ng Xue-Zhong Wang Department of Mathematics The University of Hong KongHong KongChina School of Mathematics and Statistics Hexi University734000 ZhangyeGansu ProvinceChina

Tensor robust principal component analysis has received a substantial amount of attention in various *** existing methods,normally relying on tensor nuclear norm minimization,need to pay an expensive computational cost due to multiple singular value decompositions at each *** overcome the drawback,we propose a scalable and efficient method,named parallel active subspace decomposition,which divides the unfolding along each mode of the tensor into a columnwise orthonormal matrix(active subspace)and another small-size matrix in *** a transformation leads to a nonconvex optimization problem in which the scale of nuclear norm minimization is generally much smaller than that in the original *** solve the optimization problem by an alternating direction method of multipliers and show that the iterates can be convergent within the given stopping criterion and the convergent solution is close to the global optimum solution within the prescribed *** results are given to demonstrate that the performance of the proposed model is better than the state-of-the-art methods.

关键词： Principal component analysis Low-rank tensors Nuclear norm minimization Active subspace decomposition Matrix factorization