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Jerk-limited feedrate scheduling and optimization for five-axis machining using new piecewise linear programming approach

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Science China(Technological Sciences) 2019年第7期62卷 1067-1081页

作者： SUN YuWen CHEN ManSen JIA JinJie lee yuan-Shin GUO DongMing School of Mechanical Engineering Dalian University of Technology Dalian 116024 China Department of Industrial and Systems Engineering North Carolina State University Raleigh NC 27695 USA

In this paper, a new computation method and an optimization algorithm are presented for feedrate scheduling of five-axis machining in compliance with both machine drive limits and process limits. Five-axis machine tool with its ability of controlling tool orientation to follow the sculptured surface contour has been widely used in modern manufacturing industry. Feedrate scheduling serving as a kernel of CNC control system plays a critical role to ensure the required machining accuracy and reliability for five-axis machining. Due to the nonlinear coupling effects of all involved drive axes and the saturation limit of servo motors, the feedrate scheduling for multi-axis machining has long been recognized and remains as a critical challenge for achieving five-axis machine tools’ full capacity and advantage. To solve the nonlinearity nature of the five-axis feedrate scheduling problems, a relaxation mathematical process is presented for relaxing both the drive motors’ physical limitations and the kinematic constraints of five-axis tool motions. Based on the primary optimization variable of feedrate, the presented method analytically linearizes the machining-related constraints, in terms of the machines’ axis velocities, axis accelerations and axis jerks. The nonlinear multi-constrained feedrate scheduling problem is transformed into a manageable linear programming problem. An optimization algorithm is presented to find the optimal feedrate scheduling solution for the five-axis machining problems. Both computer implementation and laboratorial experiment testing by actual machine cutting were conducted and presented in this paper. The experiment results demonstrate that the proposed method can effectively generate efficient feedrate scheduling for five-axis machining with constraints of the machine tool physical constraints and limits. Compared with other existing numerical methods, the proposed method is able to find an accurate analytical solution for the nonlinear cons

关键词： five-axis machining feedrate scheduling jerk linear programming optimization

Fabrication of Microlens Array and Its Application:A Review

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 10-18页

作者： Wei yuan Li-Hua Li Wing-Bun lee Chang-Yuen Chan State Key Laboratory of Ultra-precision Machining Technology Partner Laboratory in the Hong Kong Polytechnic University Shenzhen Branch of State Key Laboratory of Ultra-precision Machining Technology PolyU Shenzhen Research Institute

Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.

关键词： Microlens array Ultraprecision machining 3D image system MEMS

OWC air chamber performance prediction under impulse turbine damping effects

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Science China(Technological Sciences) 2016年第4期59卷 657-666页

作者： LIU Zhen HYUN BeomSoo JIN Ji yuan HONG KeyYong lee YoungYeon Shandong Provincial Key Laboratory of Ocean Engineering Ocean University of China Qingdao Municipal Key Laboratory of Ocean Renewable Energy Ocean University of China College of Ocean Science and Technology Korea Maritime and Ocean University Ocean Plant Research Division Korea Research Institute of Ships and Ocean Engineering

Oscillating water columns(OWCs)are most widely used in coastal wave energy *** air duct opens into the atmosphere through the air turbine,which is the power take-off device,and this results in a pressure drop across the air ***,because of the complex configure of the impulse turbine and its high rotation speed,it is difficult to install it in the experimental simulator and numerical ***,the turbine damping effects on the operation of the OWC air chamber are induced to predict its performance more *** plates are used as a substitute for the impulse turbine as it generates a similar pressure drop and power output;the experimental and numerical pressure drops and output powers are compared.A 3D numerical wave tank based on the two-phase VOF model is established using the commercial CFD code Fluent,which can predict air flow and pressure variations in the chamber and *** surface elevations,air flow velocity and pressure variation inside the chamber with the orifice plate are studied numerically,and validated by the corresponding experimental *** air chamber of the Yongsoo OWC pilot plant is used as the engineering project *** operating performance of the air chamber installed with a 0.428D orifice plate as the substitute for the designed impulse turbine is computed and *** is found that the turbine damping effects will cause around 30%reduction in the peak values of the pneumatic energy output of the OWC air chamber in the resonant wave domain.

关键词： oscillating water column air chamber turbine damping effects pressure drop orifice plate operating performance

What could probiotic do for us?

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Food Science and Human Wellness 2014年第2期3卷 47-50页

作者： yuan Kun lee Department of Microbiology Yong Loo Lin School of MedicineNational University of Singapore5 Science Drive 2Singapore 117597Singapore

Gastrointestinal microbes play important roles in the health and disease of the *** are many documented evidences which demonstrated that disturbance of intestinal microbiota is linked to the risk of developing infectious,inflammatory and allergic *** intestine is home for a complex consortium of 1013–1014 microbial *** between the intestinal microbes,pathogens and the host lead to exclusion of toxins(mycotoxins)and pathogens(colonization resistance),interference in disease progression as demonstrated in the prevention of oral infection,dental caries,diarrhoeas(Antibiotic Associated Diarrhoea,Travellers’Diarrhoea and Rotavirus Diarrhoea),postoperative infection,respiratory infection and certain *** group of beneficial intestinal microbes termed probiotics alter intestinal epithelial cell tight junction and immunological ***,laboratory and clinical studies demonstrated gut-brain axis communication and intestinal microbial(both pathogens and probiotics)modulation of host psycho-neuroimmunological functions,in relation to depression,anxiety and memory *** open up many possibilities of probiotics supplementation for moderating intestinal microbiota as an approach in disease prevention and treatment.

关键词： prevention intestine allergic

Relationship of multidrug-resistant gene and extended-spectrum carbapenem-resistance in Staphylococcus aureus

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BIOCELL 2019年第4期43卷 263-269页

作者： yuan LI YONGHYUN lee YIELHEA SEO YOUJIN HWANG Department of Life Science College of Bio-nano TechnologyGachon UniversityIncheon21936Korea Department of Health Sciences and Technology GAIHSTGachon UniversityIncheon21999Korea Department of Laboratory Medicine Gil HospitalGachon University College of MedicineIncheonKorea

The aim of this study was to determine the relationship between phenotypic antimicrobial susceptibility patterns and extended-spectrum,carbapenem-resistance genes.A total of 109 clinical Staphilococcus aureus strains were subjected to 19 antimicrobial susceptibility *** to methicillin(mecA),penicillin(blaTEM),and tetracycline(tetM)was *** compared the presence of the blaTEM genes with extended-spectrum,carbapenem-related genes and identified the types of SCCmec *** 109 clinical *** strains,62(56.88%)had methicillin resistance and 60 strains carried *** prevalence of blaTEM and tetM genes was 81.65%and 37.61%,*** most predominant SCCmec type was SCCmec type Ⅱ 28/60(46.67%),in 60 mecA-positive methicillin-resistant ***(MRSA)*** SCCmec prevalence rates were type ⅣA 30.00%(18/60),type Ⅳb 8.33%(5/60),type Ⅳd 6.67%(4/60),and non-typable 8.33%(5/60).Sixty of the 109(55.05%)MRSA isolates were positive for extended-spectrum carbapenems(31/60)(51.67%),cephalosporins 40/60(66.67%)and carbapenems 31/60(51.67%).The predominant SCCmec type II demonstrated more carbapenem-resistance than the ⅣA,Ⅳb and Ⅳd types.

关键词： MRSA BlaTEM BlaNDM CCmec typeⅡ Type IVA Extended-spectrum carbapenems

How much information is lost when sampling driving behavior data?Indicators to quantify the extent of information loss

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Journal of Intelligent and Connected Vehicles 2020年第1期3卷 17-29页

作者： Jun Liu Asad Khattak lee Han Quan yuan Department of Civil Construction and Environmental EngineeringThe University of AlabamaTuscaloosaAlabamaUSA Department of Civil and Environmental Engineering The University of TennesseeKnoxvilleTennesseeUSA State Key Laboratory of Automotive Safety and Energy School of Vehicle and MobilityTsinghua UniversityBeijingChina

Purpose–Individuals’driving behavior data are becoming available widely through Global Positioning System devices and on-board diagnostic *** incoming data can be sampled at rates ranging from one Hertz(or even lower)to hundreds of *** to capture substantial changes in vehicle movements over time by“undersampling”can cause loss of information and misinterpretations of the data,but“oversampling”can waste storage and processing *** purpose of this study is to empirically explore how micro-driving decisions to maintain speed,accelerate or decelerate,can be best captured,without substantial loss of ***/methodology/approach–This study creates a set of indicators to quantify the magnitude of information loss(MIL).Each indicator is calculated as a percentage to index the extent of information loss(EIL)in different *** overall information loss index named EIL is created to combine the MIL *** from a driving simulator study collected at 20 Hertz are analyzed(N=718,481 data points from 35,924 s of driving tests).The study quantiﬁes the relationship between information loss indicators and sampling ***–The results show that marginally more information is lost as data are sampled down from 20 to 0.5 Hz,but the relationship is not *** four indicators of MILs,the overall EIL is 3.85 per cent for 1-Hz sampling rate driving behavior *** sampling rates are higher than 2 Hz,all MILs are under 5 per cent for importation ***/value–This study contributes by developing a framework for quantifying the relationship between sampling rates,and information loss and depending on the objective of their study,researchers can choose the appropriate sampling rate necessary to get the right amount of accuracy.

关键词： Driver behaviours and assistance Sensor data processing Information loss Instantaneous driving decisions Sampling rate Undersampling

Infant intestinal Enterococcus faecalis down-regulates inflammatory responses in human intestinal cell lines

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World Journal of Gastroenterology 2008年第7期14卷 1067-1076页

作者： Lydia Hui Mei Ng Wai Ling Chow yuan Kun lee Department of Microbiology National University of Singapore5 Science Drive 2Singapore 117597Republic of Singapore

AIM: To investigate the ability of Lactic acid bacteria (LAB) to modulate inflammatory reaction in human intestinal cell lines (Caco-2, HT-29 and HCT116). Different strains of LAB isolated from new born infants and fermented milk, together with the strains obtained from culture collections were ***: LABs were treated with human intestinal cell lines. ELISA was used to detect IL-8 and TGF-β protein secretion. Cytokines and Toll like receptors (TLRs) gene expression were assessed using RT-PCR. Conditional medium, sonicated bacteria and UV killed bacteria were used to find the effecter molecules on the bacteria. Carbohydrate oxidation and protein digestion were applied to figure out the molecules' residues. Adhesion assays were further carried ***: It was found that Enterococcus faecalis is the main immune modulator among the LABs by downregulation of IL-8 secretion and upregulation of TGF-β. Strikingly, the effect was only observed in four strains of E. faecalis out of the 27 isolated and tested. This implies strain dependent immunomodulation in the host. In addition, E. faecalis may regulate inflammatory responses through TLR3, TLR4, TLR9 and TRAF6. Carbohydrates on the bacterial cell surface are involved in both its adhesion to intestinal cells and regulation of inflammatory responses in the host. CONCLUSION: These data provide a case for the modulation of intestinal mucosal immunity in which specific strains of E. faecalis have uniquely evolved to maintain colonic homeostasis and regulate inflammatory responses.

关键词： Lactic acid bacteria E. faecalis Inflammation IL-8 TLRs

Growth and characterization of Bi(110)/CrTe_(2) heterostructures:Exploring interplay between magnetism and topology

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Chinese Physics B 2024年第2期33卷 449-455页

作者：袁震宇杨发枝吕佰晴黄耀波钱天徐金朋丁洪 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences(CAS)Beijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Tsung-Dao lee Institute and School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China Songshan Lake Materials Laboratory Dongguan 523808China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China School of Physics Shandong UniversityJi’nan 250100 China

The interplay between topology and magnetism is vital for realizing exotic quantum phenomena,significant examples including quantum anomalous Hall effect,axion insulators,and high-order topological *** states host great potential for future applications in high-speed and low-consumption electronic *** being extensively investigated,practical platforms are still *** this work,with molecular beam epitaxy(MBE),we provide the first experimental report on high-quality Bi(110)/CrTe_(2) magnetic *** employing in-situ high-resolution scanning tunneling microscopy,we are able to examine the interaction between magnetism and *** is a potential edge state at an energy level above the Fermi level,but no edge states observed near the Fermi level The absence of high-order topological corner states near EF highlights the importance of lattice matching and interface engineering in designing high-order topological *** study provides key insights into the interplay between two-dimensional magnetic and topological materials and offers an important dimension for engineering magnetic topological states.

关键词： bismuth(110) chromium ditelluride(CrTe_(2)) topological states scanning tunneling microscopy(STM)

Fuzzy optimization design of multicomponent refinery hydrogen network

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Chinese Journal of Chemical Engineering 2022年第8期35卷 125-139页

作者： Chun Deng Xuantong Lu Qixin Zhang Jian Liu Jui-yuan lee Xiao Feng State Key Laboratory of Heavy Oil Processing College of Chemical Engineering and EnvironmentChina University of PetroleumBeijing 102249China PetroChina Daqing Petrochemical Company Daqing 163000China Department of Chemical Engineering and Biotechnology National Taipei University of TechnologyTaipei 10608China School of Chemical Engineering&Technology Xi’an Jiaotong UniversityXi’an 710049China

Hydrogen and light hydrocarbon components are essential resources of the *** optimization of the refinery hydrogen system and recovery of the light hydrocarbon components contained in the gas streams are key strategies to reduce the operating costs for sustainable *** research efforts have been focused on the optimization of single impurity hydrogen network,and the flowrates of the hydrogen sources and sinks are assumed to be ***,their flowrates vary along with the quality of crude oil and refinery processing plans.A general superstructure of multicomponent refinery hydrogen network is proposed,which considers four components,namely H_(2),H_(2)S,CH_(4) and C_(2+),as well as the flowrate variations of hydrogen source and hydrogen *** mathematical model based on the superstructure is developed with objective functions,including the minimization of total annualized cost and the maximization of overall satisfaction of the hydrogen ***,the model considers the removal of hydrogen sulfide and the recovery of light hydrocarbon components(i.e.,C_(2+))in the *** verify the applicability of the proposed mathematical model,a simplified industrial case study with four scenarios is *** optimization results show that the economic benefit can be maximized by considering both the direct reuse of gas streams from high-pressure separator(HP gas stream)and from low-pressure separator(LP gas stream)and the recovery of the light hydrocarbon *** fuzzy optimization method can be used to guide the optimal design of the refinery hydrogen system with multi-period variable flowrates.

关键词： Hydrogen network Mathematical programming Multicomponent Fuzzy optimization Light hydrocarbon recovery