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Thermoelastic Analysis of Non-uniform Pressurized Functionally Graded Cylinder with Variable Thickness Using First Order Shear Deformation Theory(FSDT) and Perturbation Method

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Chinese Journal of mechanical engineering 2015年第6期28卷 1149-1156页

作者： KHOSHGOFTAR M J MIRZAALI M J RAHIMI G H Faculty of mechanical engineering Tarbiat Modares University department of mechanical engineering Faculty of Engineering Arak University department of mechanical engineering Politecnico di Milano

Recently application of functionally graded materials（FGMs） have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs. Such composites with varying thickness and non-uniform pressure can be used in the aerospace engineering. Therefore, analysis of such composite is of high importance in engineering problems. Thermoelastic analysis of functionally graded cylinder with variable thickness under non-uniform pressure is considered. First order shear deformation theory and total potential energy approach is applied to obtain the governing equations of non-homogeneous cylinder. Considering the inner and outer solutions, perturbation series are applied to solve the governing equations. Outer solution for out of boundaries and more sensitive variable in inner solution at the boundaries are considered. Combining of inner and outer solution for near and far points from boundaries leads to high accurate displacement field distribution. The main aim of this paper is to show the capability of matched asymptotic solution for different non-homogeneous cylinders with different shapes and different non-uniform pressures. The results can be used to design the optimum thickness of the cylinder and also some properties such as high temperature residence by applying non-homogeneous material.

关键词： non-homogenous cylinder First order Shear Deformation Theory matched asymptotic method perturbation method functionally graded material

Using computed tomography scans to develop an ex-vivo gastric model

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World Journal of Gastroenterology 2007年第9期13卷 1372-1377页

作者： Jerome A Henry Gerard O’Sullivan Abhay S Pandit department of mechanical and biomedical engineering and National Centre for Biomedical Engineering Science National University of Ireland Galway Ireland Section of Interventional Radiology Department of Radiology University College Hospital GalwayIreland

The objective of this research was to use abdominal computed tomography (CT) scans to non-invasively quantify anthropometrical data of the human stomach and to concomitantly create an anatomically correct and distensible ex-vivo gastric model. Thirty-three abdominal CT scans of human subjects were obtained and were imported into reconstruction software to generate 3D models of the stomachs. Anthropometrical data such as gastric wall thickness, gastric surface area and gastric volume were subsequently quantified. A representative 3D computer model was exported into a selective laser sintering (SLS) rapid prototyping machine to create an anatomically correct solid gastric model. Subsequently, a replica wax template of the SLS model was created. A negative mould was offset around the wax template such that the offset distance was equivalent to that of the gastric wall thickness. A silicone with similar mechanical properties to the human stomach was poured into the offset. The lost wax manufacturing technique was employed to create a hollow distensible stomach model. 3D computer gastric models were generated from the CT scans. A hollow distensible silicone ex-vivo gastric model with similar compliance to that of the human stomach was created. The anthropometrical data indicated that there is no significant relationship between BMI and gastric surface area or gastric volume. There were inter- and intra-group differences between groups with respect to gastric wall thickness. This study demonstrates that abdominal CT scans can be used to both non-invasively determine gastric anthropometrical data as well as create realistic ex-vivo stomach models.

关键词： Gastric anthropometrical data Rapid prototyping Ex-vivo gastric model Computed tomography

Cell biomechanics and its applications in human disease diagnosis

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Acta Mechanica Sinica 2015年第2期31卷 268-273页

作者： Yasaman Nematbakhsh Chwee Teck Lim NUS Graduate School for Integrative Sciences and engineering department of biomedical engineering National University of Singapore department of mechanical engineering National University of Singapore Mechanobiology Institute National University of Singapore

Certain diseases are known to cause changes in the physical and biomechanical properties of *** include cancer,malaria,and sickle cell anemia among ***,such physical property changes can result in several fold increases or decreases in cell stiffness,which are significant and can result in severe pathology and eventual catastrophic breakdown of the bodily *** there are developed biochemical and biological assays to detect the onset or presence of diseases,there is always a need to develop more rapid,precise,and sensitive methods to detect and diagnose *** property changes can play a significant role in this *** such,research into disease biomechanics can not only give us an in-depth knowledge of the mechanisms underlying disease progression,but can also serve as a powerful tool for detection and *** article provides some insights into opportunities for how significant changes in cellular mechanical properties during onset or progression of a disease can be utilized as useful means for detection and *** will also showcase several technologies that have already been developed to perform such detection and diagnosis.

关键词： Biophysical properties Cancer Malaria Cell enrichment Phenotyping Diagnostic tool Mechanopathology Cell separation and capture

Improvement of Deep Groove Ball Bearing’s Performance Using a Bionic Textured Inner Race

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Journal of Bionic engineering 2021年第4期18卷 974-990页

作者： K.E.Ch.Vidyasagar R.K.Pandey Dinesh Kalyanasundaram Center for biomedical engineering Indian Institute of Technology DelhiNew Delhi110016India department of biomedical engineering College of EngineeringOsmania UniversityHyderabad500007India department of mechanical engineering Indian Institute of Technology DelhiNew Delhi110016India department of biomedical engineering All India Institute of Medical SciencesNew Delhi110029India

Micro-textured surfaces have improved the tribological performance of contact surfaces under lubricated conditions;however,not practiced due to manufacturing *** addition to simpler micro-pits or straight-trench type textures,sophisticated bioinspired textures on commercial radial ball bearings have been scarcely *** this work,Dendroaspis polylepis(Mamba snake)skin-type textures were fabricated on the inner race of FAG radial ball bearings using a nanosecond fiber laser *** the snake textures were primarily meant to enhance friction,the dimensions of the texture have been carefully chosen to improve the tribological performance under lubricated *** textured bearings were assembled and experimented at various rotational speeds and lightly loaded conditions to measure vibrational amplitude,frictional torque,and temperature *** to untextured(conventional)bearing,the snake-skin type textured bearings resulted in improved tribo-dynamic performance.

关键词： bionic texture radial ball bearing frictional torque vibration temperature

Production of "Tricalcium Phosphate/Titanium Dioxide" Coating Surface on Titanium Substrates

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Journal of Materials Science & Technology 2010年第11期26卷 1006-1010页

作者： Onder Albayrak Sabri Altintas department of mechanical engineering Mersin University department of mechanical engineering Bogazici University

A new method for the production of the coating surface consisting of tricalcium phosphate （TCP） and titanium dioxide （TiO2） on titanium （Ti） substrates by using electrophoretic deposition （EPD） method has been *** occurrence on coating surface and hydroxyapatite （HA） decomposition into TCP,which are commonly encountered in EPD method,were used as an advantage in this *** nano-powders synthesized by acid-base method were used as the coating *** were deposited on Ti substrates with different voltages and *** on the deposited surface were observed by scanning electron microscopy （SEM）.Samples were sintered in air atmosphere to allow TiO2 growth from the Ti substrate to fill the *** observation and X-ray diffraction （XRD） analysis proved the occurrence of complete decomposition of HA into TCP,TiO2 growth between cracks,and coalescence of TCP/TiO2 on coating *** type of coating surface is expected to increase the coating strength because of TiO2 growth in the cracks and its coalescence with TCP.

关键词： Electrophoretic deposition Hydroxyapatite Bioceramics Microstructure

WC-M coating to improve resistance of hydraulic turbines to cavitation erosion and abrasion

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中国有色金属学会会刊：英文版 2003年第4期13卷 893-897页

作者：王飚王宇东张自华 department of mechanical engineering

WC M hard faced ceramic coating was made on the substrate of steel by means of high velocity oxygen fuel flame (HVOF) thermal spraying. The resistance of this coating to cavitation erosion and abrasion (CEA) is about 2.5 times higher than that of 188 stainless steel, and is about 1.5 times higher than that of Stellite alloy (CoCrWC) made in America. When this coating were applied to the hydraulic power stations with more silt content in the flow water, which reaches 50 kg/m 3, the resistance of above mentioned coating to CEA was about 2 times to that of NiCr alloy coating, and is about 45 times to that of OCr13Ni4Mo stainless steel. In addition, the micro hardness, microstructures and electron probe analyzing of the WC M coating are all discussed.

关键词： WC-M涂层磨损水轮机涡轮气穴腐蚀

A reinforcement learning approach to vehicle coordination for structured advanced air mobility

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Green Energy and Intelligent Transportation 2024年第2期3卷 20-37页

作者： Sabrullah Deniz Yufei Wu Yang Shi Zhenbo Wang department of mechanical Aerospaceand Biomedical EngineeringThe University of TennesseeKnoxvilleTN37996USA

Advanced Air Mobility(AAM)has emerged as a pioneering concept designed to optimize the efficacy and ecological sustainability of air *** core objective is to provide highly automated air transportation services for passengers or cargo,operating at low altitudes within urban,suburban,and rural *** seeks to enhance the efficiency and environmental viability of the aviation sector by revolutionizing the way air travel is *** a complex aviation environment,traffic management and control are essential technologies for safe and effective AAM *** of the most difficult obstacles in the envisioned AAM systems is vehicle coordination at merging points and *** escalating demand for air mobility services,particularly within urban areas,poses significant complexities to the execution of such *** this study,we propose a novel multi-agent reinforcement learning(MARL)approach to efficiently manage high-density AAM operations in structured *** approach provides effective guidance to AAM vehicles,ensuring conflict avoidance,mitigating traffic congestion,reducing travel time,and maintaining safe ***,intelligent learning-based algorithms are developed to provide speed guidance for each AAM vehicle,ensuring secure merging into air corridors and safe passage through *** validate the effectiveness of our proposed model,we conduct training and evaluation using BlueSky,an open-source air traffic control simulation *** the simulation of thousands of aircraft and the integration of real-world data,our study demonstrates the promising potential of MARL in enabling safe and efficient AAM *** simulation results validate the efficacy of our approach and its ability to achieve the desired outcomes.

关键词： Advanced Air Mobility(AAM) Urban Air Mobility(UAM) Air Traffic Control(ATC) Multi-Agent Reinforcement Learning(MARL)

Effect of Laser Welding on Properties of Dissimilar Joint of Al-Mg-Si and Al-Mn Aluminum Alloys

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Journal of Materials Science & Technology 2010年第3期26卷 276-282页

作者： C.C.Chang C.P.Chou S.N.Hsu G.Y.Hsiung J.R.Chen department of mechanical engineering National Chiao-Tung University National Synchrotron Radiation Research Center department of biomedical engineering and Environmental Sciences National Tsing-Hua University

This study discusses the welding properties for the components of an aluminum-alloy ultra-high vacuum chamber and beam position monitor （BPM）.The welding parameters include the modes of laser output （pulsed wave and continuous wave）,welding speed,shield gas flow,welding bead structure,and focusing *** results showed that the welding defect rate of the pulsed wave type was larger than that of the continuous wave *** crack in the welding bead reduced with decreasing welding *** fusion penetration of the welding bead was higher when the focusing distance was long enough to deepen into the welding *** morphology during the experimental process revealed the proper flow of shield *** adaptability design of the welding bead structure in the preceding processes had more effect on overall welding structure and morphology.

关键词： Laser welding Aluminum alloy Ultra-high vacuum Beam position monitor (BPM)

Boosting the Information Transfer Rate of an SSVEP-BCI System Using Maximal-Phase-Locking Value and Minimal-Distance Spatial Filter Banks

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Tsinghua Science and Technology 2019年第3期24卷 262-270页

作者： Ke Lin Shangkai Gao Xiaorong Gao the department of biomedical engineering Tsinghua University

For Brain-Computer Interface(BCI) systems, improving the Information Transfer Rate(ITR) is a very critical issue. This study focuses on a Steady-State Visually Evoked Potential(SSVEP)-based BCI because of its advantage of high ITR. Unsupervised Canonical Correlation Analysis(CCA)-based method has been widely employed because of its high efficiency and easy implementation. In a recent study, an ensemble-CCA method based on individual training data was proposed and achieved an excellent performance with ITR of 267 bit/min.A 40-target SSVEP-BCI speller was investigated in this study, using an integration of Minimal-Distance(MD) and Maximal-Phase-locking value(MP) approaches. In the MD approach, a spatial filter is developed to minimize the distance between the training data and the reference sine signal, and in this study, two different types of distance were compared. In the MP approach, a spatial filter is developed to maximize the Phase-Locking Value(PLV)between the training calibration data and the reference sine signal. In addition to the fundamental frequency of stimulation, the harmonics were used to train MD and MP spatial filters, which formed spatial filter banks. The test data epoch was multiplied by the MP and MD spatial filter banks, and the distances and PLVs were extracted as features for recognition. Across 12 subjects with a 0.4 s-data length, the proposed method realized an average classification accuracy and ITR of 93% and 307 bit/min, respectively, which is significantly higher than the current state-of-the-art method. To the best of our knowledge, these results suggest that the proposed method has achieved the highest ITR in SSVEP-BCI studies.

关键词： SSVEP-BCI Information Transfer Rate (ITR) spatial filter distance Phase-Locking Value (PLV)