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Chinese Journal of Mechanical Engineering 2007年第5期20卷 80-86页

作者： wong Pak-kin TAM Lap-mou LI Ke Department of Electromechanical Engineering Faculty of Science and Technology University of Macao Macao China

In modem four-stroke engine technology, variable valve timing and lift control offers potential benefits for making a high-performance engine. A novel electro-hydraulic fully variable valve train for four-stroke automotive engines is introduced. The construction of the nonlinear mathematic model of the valve train system and its dynamic analysis are also presented. Experimental and simulation results show that the novel electro-hydraulic valve train can achieve fully variable valve timing and lift control. Consequently the engine performance on different loads and speeds will be significantly increased. The technology also permits the elimination of the traditional throttle valve in the gasoline engines and increases engine design flexibility.

关键词： Fully variable engine valve train Dynamic model Simulation

Sampled-Data Asynchronous Fuzzy Output Feedback Control for Active Suspension Systems in Restricted Frequency Domain

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IEEE/CAA Journal of Automatica Sinica 2021年第5期8卷 1052-1066页

作者： Wenfeng Li Zhengchao Xie Yucong Cao Pak kin wong Jing Zhao the School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641China the Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing South China University of TechnologyGuangzhou 510641China the Automotive Engineering Institute Guangzhou Automotive Group CompanyLtd.Guangzhou 510640China the Department of Electromechanical Engineering University of MacaoMacaoChina

This paper proposes a novel sampled-data asynchronous fuzzy output feedback control approach for active suspension systems in restricted frequency *** order to better investigate uncertain suspension dynamics,the sampleddata Takagi-Sugeno(T-S)fuzzy half-car active suspension(HCAS)system is considered,which is further modelled as a continuous system with an input ***,considering that the fuzzy system and the fuzzy controller cannot share the identical premises due to the existence of input delay,a reconstructed method is employed to synchronize the time scales of membership functions between the fuzzy controller and the fuzzy ***,since external disturbances often belong to a restricted frequency range,a finite frequency control criterion is presented for control synthesis to reduce ***,given a full information of state variables is hardly available in practical suspension systems,a two-stage method is proposed to calculate the static output feedback control ***,an iterative algorithm is proposed to compute the optimum ***,numerical simulations verify the effectiveness of the proposed controllers.

关键词： Active suspension asynchronous constraints output feedback restricted frequency domain sampled-data control Takagi-Sugeno(T-S)fuzzy

An Adaptive Nonsingular Fast Terminal Sliding Mode Control for Yaw Stability Control of Bus Based on STI Tire Model

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Chinese Journal of Mechanical Engineering 2021年第4期34卷 182-195页

作者： Xiaoqiang Sun Yujun Wang Yingfeng Cai Pak kin wong Long Chen Automotive Engineering Research Institute Jiangsu UniversityZhenjiang 212013China Department of Electromechanical Engineering University of MacaoTaipaMacaoChina State Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijing 100084China

Due to the bus characteristics of large quality,high center of gravity and narrow wheelbase,the research of its yaw stability control(YSC)system has become the focus in the field of vehicle system ***,the tire nonlinear mechanical properties and the effectiveness of the YSC control system are not considered carefully in the current *** this paper,a novel adaptive nonsingular fast terminal sliding mode(ANFTSM)control scheme for YSC is proposed to improve the bus curve driving stability and safety on slippery ***,the STI(Systems Technologies Inc.)tire model,which can effectively reflect the nonlinear coupling relationship between the tire longitudinal force and lateral force,is established based on experimental data and firstly adopted in the bus YSC system *** this basis,a more accurate bus lateral dynamics model is built and a novel YSC strategy based on ANFTSM,which has the merits of fast transient response,finite time convergence and high robustness against uncertainties and external disturbances,is ***,to solve the optimal allocation problem of the tire forces,whose objective is to achieve the desired direct yaw moment through the effective distribution of the brake force of each tire,the robust least-squares allocation method is *** verify the feasibility,effectiveness and practicality of the proposed bus YSC approach,the TruckSim-Simulink co-simulation results are finally *** co-simulation results show that the lateral stability of bus under special driving conditions has been significantly *** research proposes a more effective design method for bus YSC system based on a more accurate tire model.

关键词： Bus Yaw stability control Sliding mode control STI tire model Co-simulation

Ignition Pattern Analysis for Automotive Engine Trouble Diagnosis Using Wavelet Packet Transform and Support Vector Machines

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 870-878页

作者： VONG Chi-man wong Pak-kin TAM Lap-mou ZHANG Zaiyong Department of Computer and Information Science Faculty of Science and Technology University of Macao Macao China Department of Electromechanical Engineering Faculty of Science and Technology University of Macao Macao China

Engine spark ignition is an important source for diagnosis of engine *** on the waveform of the ignition pattern,a mechanic can guess what may be the potential malfunctioning parts of an engine with his/her experience and ***,this manual diagnostic method is imprecise because many spark ignition patterns are very ***,a diagnosis needs many trials to identify the malfunctioning *** the mechanic needs to disassemble and assemble the engine parts for *** tackle this problem,an intelligent diagnosis system was established based on ignition ***,the captured patterns were normalized and *** wavelet packet transform（WPT） was employed to extract the representative features of the ignition ***,a classification system was constructed by using multi-class support vector machines（SVM） and the extracted *** classification system can intelligently classify the most likely engine fault so as to reduce the number of diagnosis *** results show that SVM produces higher diagnosis accuracy than the traditional multilayer feedforward neural *** is the first trial on the combination of WPT and SVM to analyze ignition patterns and diagnose automotive engines.

关键词： automotive engine ignition pattern diagnosis pattern classification wavelet packet transform support vector machines.

Deep learning for diagnosis of precancerous lesions in upper gastrointestinal endoscopy:A review

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World Journal of Gastroenterology 2021年第20期27卷 2531-2544页

作者： Tao Yan Pak kin wong Ye-Ying Qin School of Mechanical Engineering Hubei University of Arts and ScienceXiangyang 441053Hubei ProvinceChina Department of Electromechanical Engineering University of MacaoTaipa 999078MacaoChina

Upper gastrointestinal(GI)cancers are the leading cause of cancer-related deaths *** identification of precancerous lesions has been shown to minimize the incidence of GI cancers and substantiate the vital role of screening ***,unlike GI cancers,precancerous lesions in the upper GI tract can be subtle and difficult to *** intelligence techniques,especially deep learning algorithms with convolutional neural networks,might help endoscopists identify the precancerous lesions and reduce interobserver *** this review,a systematic literature search was undertaken of the Web of Science,PubMed,Cochrane Library and Embase,with an emphasis on the deep learning-based diagnosis of precancerous lesions in the upper GI *** status of deep learning algorithms in upper GI precancerous lesions has been systematically *** challenges and recommendations targeting this field are comprehensively analyzed for future research.

关键词： Artificial intelligence Deep learning Convolutional neural network Precancerous lesions Endoscopy

Static-Output-Feedback Based Robust Fuzzy Wheelbase Preview Control for Uncertain Active Suspensions With Time Delay and Finite Frequency Constraint

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IEEE/CAA Journal of Automatica Sinica 2021年第3期8卷 664-678页

作者： Wenfeng Li Zhengchao Xie Jing Zhao Pak kin wong Hui Wang Xiaowei Wang School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhouand Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced ManufacturingSouth China University of TechnologyGuangzhou 510641China Department of Electromechanical Engineering University of MacaoMacao 999078 Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing South China University of TechnologyGuangzhou 510641China Department of Electromechanical Engineering University of MacaoMacao 999078China School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641China School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China

This paper proposes a static-output-feedback based robust fuzzy wheelbase preview control algorithm for uncertain active suspensions with time delay and finite frequency ***,a Takagi-Sugeno(T-S)fuzzy augmented model is established to formulate the half-car active suspension system with consideration of time delay,sprung mass variation and wheelbase preview ***,in view of the resonation between human’s organs and vertical vibrations in the frequency range of 4–8 Hz,a finite frequency control criterion in terms of H∞norm is developed to improve ride ***,other mechanical constraints are also considered and satisfied via generalized H2 ***,in order to maintain the feasibility of the controller despite of some state variables are not online-measured,a two stage approach is adopted to derive a static output feedback ***,numerical simulation results illustrate the excellent performance of the proposed controller.

关键词： Active suspension finite frequency output feedback Takagi-Sugeno(T-S)fuzzy model time delay wheelbase preview

Design of a Five-Band Dual-Port Rectenna for RF Energy Harvesting

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Computers, Materials & Continua 2021年第10期69卷 487-501页

作者： Surajo Muhammad Jun Jiat Tiang Sew kin wong Jamel Nebhen Amjad Iqbal Centre for Wireless Technology Faculty of EngineeringMultimedia UniversityCyberjaya63100Malaysia College of Computer Science and Engineering Prince Sattam Bin Abdulaziz UniversityAlkharj11942Saudi Arabia

This paper proposed the design of a dual-port rectifier with multifrequency *** RF rectifier is achieved using a combination of L-section inductive impedance matching network(IMN)at Port-1 with a multiple stubs impedance transformer at *** fabricated prototype can harvest RF signal from GSM/900,GSM/1800,UMTS/2100,Wi-Fi/2.45 and LTE/2600 frequency bands at(0.94,1.80,2.10,2.46,and 2.63 GHz),*** rectifier occupies a small portion of a PCB board at 0.20λg×0.15λ*** proposed circuit realized a measured peak RF-to-dc(radio frequency direct current)power conversion efficiency(PCE)of(21%,22.76%,25.33%,21.57%,and 22.14%)for an input power of−20 *** RF harvester attains a measured peak RF-to-dc PCE of 72.70%and an output dc voltage of 154 mV for an input power of 3 dBm at 2.46 *** of the proposed rectifier in the ambiance gives a peak dc output voltage of 376.1 mV from the five signal ***,a low-powered bq25504-674 evaluation module(EVM)is integrated with the *** module boost and drive the rectifier output dc voltage to 945 *** performance of the proposed rectifier in the ambiance environment makes it a suitable module for low-powered RF applications.

关键词： RF energy harvesting impedance matching network power conversion efficiency multi-band rectifier

Radar-based Characteristics and Formation Environment of Supercells in the Landfalling Typhoon Mujigae in 2015

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Advances in Atmospheric Sciences 2022年第5期39卷 802-818页

作者： Lanqiang BAI Zhiyong MENG Ruilin ZHOU Guixing CHEN Naigeng WU Wai-kin wong School of Atmospheric Sciences Sun Yat-sen Universityand Key Laboratory of Tropical Atmosphere-Ocean SystemMinistry of Educationand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510640China Hong Kong Observatory Hong Kong 999077China

This study presents the radar-based characteristics and formation environment of supercells spawned by the tornadic landfalling Typhoon Mujigae(2015)in October *** than 100 supercells were identified within a 24-hour period around the time of the typhoon’s landfall,of which three were tornadic with a rotational intensity clearly stronger than those of non-tornadic *** identified supercells were concentrated within a relatively small area in the northeast quadrant beyond 140 km from the typhoon *** supercells were found more likely to form over flat topography and were difficult to maintain in mountainous *** the study period,more supercells formed offshore than *** mesocyclones of the identified supercells were characterized by a small diameter generally less than 5 km and a shallow depth generally less than 4 km above ground *** environmental analysis revealed that the northeast quadrant had the most favorable conditions for the genesis of supercell in this typhoon *** nondimensional supercell composite parameter(SCP)and entraining-SCP(E-SCP)were effective in separating supercell from non-supercell *** though the atmosphere in the typhoon’s northeast quadrant was characterized by an E-SCP/SCP value supportive of supercell organization,orography was an impeditive factor for the supercell *** findings support the use of traditional parameters obtained from midlatitude supercells to assess the supercell potential in a tropical cyclone envelope.

关键词： supercell tropical cyclone atmospheric environment radar meteorology

Multiplex real-time PCR revealed very high prevalence of soil-transmitted helminth infections among aborigines in Peninsular Malaysia

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Asian Pacific Journal of Tropical Medicine 2020年第12期13卷 550-556页

作者： Nurulhasanah Othman Noorizan Miswan Weng-kin wong Boon-huat Lim Rahmah Noordin Institute for Research in Molecular Medicine Universiti Sains Malaysia11800 PenangMalaysia School of Health Sciences Universiti Sains Malaysia16150 KelantanMalaysia

Objective:To determine the true prevalence of soil-transmitted helminth infections in the Malaysian aborigines using real-time ***:A total of 122 aborigines from seven tribes were recruited from settlements and nearby hospitals which served the communities,located in four states in Peninsular *** stool samples were examined for the presence of soil-transmitted helminth using real-time PCR and *** latter included the direct wet mount and formalin-ether concentration technique(FECT).The infection load in FECT-positive samples was determined by the Kato-Katz *** real-time analyzer detected five helminth species using two sets of ***:The real-time PCR detected soil-transmitted helminth in 98.4% samples(n=122),which were 1.56 times higher than by *** lumbricoides and Trichuris trichiura were detected in more than 90% of the samples,while hookworm was detected in 46.7%(Necator americanus) and 13.9%(Ancylostoma sp.)of the *** with previous reports on the Malaysian aborigines showed that the real-time PCR markedly improved the detection of Ascaris lumbricoides,hookworm and Strongyloides *** real-time PCR detected poly-helminths in 92.6%of the samples compared to 28.7% by *** addition,27 samples(22.1%) showed amplification of Strongyloides stercoralis ***:The real-time PCR showed very high prevalence rates of soil-transmitted helminth infections in the aborigines and is the recommended method for epidemiological investigation of soiltransmitted helminth infections in this population.

关键词： prevalence infections markedly

A Compact Dual-Port Multi-Band Rectifier Circuit for RF Energy Harvesting

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Computers, Materials & Continua 2021年第7期68卷 167-184页

作者： Surajo Muhammad Jun Jiat Tiang Sew kin wong Amjad Iqbal Amor Smida Mohamed Karim Azizi Centre for Wireless Technology Faculty of EngineeringMultimedia UniversityCyberjaya63100Malaysia Department of Medical Equipment Technology College of Applied Medical SciencesMajmaah UniversityAlMajmaah11952Saudi Arabia Department of Physics Microwave Electronics Research LaboratoryFaculty of MathematicalPhysical and Natural Sciences of TunisTunis El Manar UniversityTunis2092Tunisia

This paper presents a compact multi-band rectifier with an improved impedance matching *** uses a combination of–matching network(MN)at Port-1,with a parallel connection of three cell branch MN at *** proposed impedance matching network(IMN)is adopted to reduce circuit complexity,to improve circuit performance,and power conversion efficiency(PCE)of the rectifier at low input *** fabricated rectifier prototype operates at 0.92,1.82,2.1,2.46 and 2.65 GHz covering GSM/900,GSM/1800,UMTS2100,and Wi-Fi/2.45–*** size of the compact rectifier on the PCB board is 0.13λ_(g)×0.1λ_(g).The fabricated rectifier achieved an RF-to DC(radio frequency direct current)PCE of 31.8%,24%,22.7%,and 15%,and 14.1%for−20 dBm at the five respective measured operating *** circuit attains a peak RF-to-DC PCE of 82.3%for an input power of 3 dBm at 0.92 *** proposed rectifier realizes an ambient output dc voltage of 454 mV for multi-tone input signals from the two *** rectifier drives a bq25504-674 power management module(PMM)to achieve 1.21 V from the two-port *** rectifier has the ability to exploit both frequency domain through the multi-band operation with good impedance bandwidth and a spatial domain using dual-port ***,it is a potential candidate for various applications in radio frequency energy harvesting(RFEH)system.

关键词： RF energy harvesting impedance matching network power conversion efficiency multi-band rectifier dual-port power management module