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作者： Ngcobo, Mduduzi E.K. Delele, Mulugeta A. Opara, Umezuruike Linus Zietsman, Cobus J. Meyer, Chris J. Department of Horticultural Science Faculty of AgriSciences University of Stellenbosch Private Bag X1 Matieland 7602 South Africa Department of Mechanical and Mechatronics Engineering Faculty of Engineering University of Stellenbosch Private Bag X1 Matieland 7602 South Africa Perishable Products Export Control Board 45 Silwerboom Avenue Platterkloof Parow 7500 South Africa

Postharvest handling of table grape is commonly carried out using multi-scale packages comprised of the main container, inner liner film and pouches holding individual bunch of berries. Total pressure drop through different table grapes packages systems were measured and the percentage contributions of each package component and the fruit bulk were determined. The liner films contributed significantly to total pressure drop for all package combinations, ranging from 40.33 ± 1.15% for micro-perforated liner film to 83.34 ± 2.13% for non-perforated liner film. The total pressure drop through the grape bulk (1.40 ± 0.01% to 9.41 ± 1.23%) was the least compared to the different packaging combinations with different levels of liner perforation. © 2011 Elsevier Ltd and IIR.

关键词： Pressure drop

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Measurement of blade tip clearance using an ultrasonic sensor 35th

Measurement of blade tip clearance using an ultrasonic senso...

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35th Aerospace Sciences Meeting and Exhibit, 1997

作者： Tagashira, Takeshi Sugiyama, Nanahisa Matsuda, Yukio Matsuki, Masakatsu Engine Control Lab Aeroengine Division National Aerospace Laboratory 7-44-1 Jindaiji-Higashi Chofu Tokyo182 Japan Department of Mechanical Engineering Nippon Institute of Technology 4-1 Miyashiro Minami-SaitamaSaitama345 Japan

This paper describes a development and evaluation of a blade tip clearance measurement system using an ultrasonic sensor. Special features of this system are;(i) it is adequate for metal and non-metal blade;(ii) it permits measurement without contact;(iii) it can work in dirty environment;and (iv) it is easy to install. Experimental results using a rotating blade test rig are described. Blade tip speed is restricted to Mach 0.18 due to the limitation of the test rig. It is concluded that the ultrasonic method is a promising candidate for an on-line clearance control of gas turbine engines. © 1997, American Institute of Aeronautics and Astronautics, Inc.

关键词： Gas turbines

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Effects of post heat treatment on microstructure and mechanical properties of Ti5553 parts made by laser powder bed fusion

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Journal of Alloys and Compounds 2023年第1期938卷

作者： Ramachandiran, Nivas Asgari, Hamed Dibia, Francis Eybel, Roger Muhammad, Waqas Gerlich, Adrian Toyserkani, Ehsan Lab Department of Mechanical and Mechatronics Engineering University of Waterloo WaterlooONN2L 3G1 Canada Lab Department of Mechanical and Mechatronics Engineering University of Waterloo WaterlooONN2L 3G1 Canada Safran Landing Systems 574 Monarch Avenue AjaxONL1S 2G8 Canada Department of Mechanical and Mechatronics Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Rapid heating and solidification rates involved in additive manufacturing result in non-homogenous microstructural features, microsegregation and residual stresses, leading to deteriorated mechanical properties. Although the rather new Ti-5553 (Ti‐5Al‐5Mo‐5V‐3Cr) metastable β-Ti alloy is printable by laser powder-bed fusion (LPBF), it exhibits poor mechanical strength compared to conventionally forged components due to the lack of second phase strengthening in the as-printed state. Therefore, post-processing heat treatment is essential to enhance the mechanical properties of the printed parts. In this research work, LPBF-made Ti-5553 specimens were subjected to varying heat treatment cycles to modify their corresponding microstructure in terms of the morphology and distribution of α particles. Differential Scanning Calorimetry (DSC), X-Ray diffraction (XRD) patterns, and electron backscatter diffraction (EBSD) results suggest that solutionizing at the upper α + β region (800 °C) offers a good combination of finer grain size and satisfactory α dissolution. On aging in the range of 500 – 700 °C for 0.5 – 4 h, growth of α particles with different morphologies was observed. A combination of multiple α morphologies, including Widmanstätten, lenticular, cylindrical and lamellar was identified based on the heat treatment conditions. Consequently, a wide range of microhardness from 300 to 500 HV was observed due to phase transformations in the microstructure, which control the mechanical properties. The subsequent tensile tests validated the improved mechanical properties further as the tensile strength increased from 780 ± 10–1640 ± 6.29 MPa, compared to the as-printed specimens. Examination of the fracture surfaces revealed intergranular failure following aging at 500 °C due to segregation of α particles at grain boundaries. At 600 °C, the fracture was initially intergranular, which slowly transformed to a ductile fracture with time. At 700 °C, the fracture was mainly duc

关键词： Titanium alloys

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Flight control design for a highly flexible flutter demonstrator

Flight control design for a highly flexible flutter demonstr...

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AIAA Scitech Forum, 2019

作者： Luspay, Tamás Baár, Tamás Teubl, Dániel Vanek, Bálint Ossmann, Daniel Wüstenhagen, Matthias Pusch, Manuel Kier, Thiemo Waitman, Sérgio Iannelli, Andrea Marcos, Andres Lowenberg, Mark Systems and Control Lab Institute for Computer Science and Control Kende u 13-17 Budapest Hungary DLR German Aerospace Center Institute of Robotics and Mechatronics Wessling82234 Germany Aerospace Engineering Department University of Bristol University Walk BristolBS8 1TR United Kingdom

ISBN: (数字)9781624105784

ISBN: (纸本)9781624105784

The paper presents the control design approaches for the European research project FLEXOP. The ultimate goal is to develop and apply active flutter suppression and load alleviation techniques on an unmanned flying aircraft demonstrator. Due to the flexible wing of the aircraft new challenges rise for the control design: the traditional rigid body (baseline) control loops have to be augmented with flutter control laws. In our approach, the controllers are designed based on a dynamical model, which is briefly discussed first. Details of the baseline control design, as well as the two different flutter suppression algorithms are discussed in the paper. Hardware-in-the-Loop testing of the controllers are reported before the first test flights of the aircraft. © 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： controllers

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Two‑Dimensional Black Phosphorus Nanomaterials:Emerging Advances in Electrochemical Energy Storage Science

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Nano-Micro Letters 2020年第12期12卷 284-317页

作者： Junye Cheng Lingfeng Gao Tian Li Shan Mei Cong Wang Bo Wen Weichun Huang Chao Li Guangping Zheng Hao Wang Han Zhang Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China Collaborative Innovation Center for Optoelectronic Science and Technology International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education and Guangdong ProvinceShenzhen UniversityShenzhen 518060People’s Republic of China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA 19104USA Nantong Key Lab of Intelligent and New Energy Materials College of Chemistry and Chemical EngineeringNantong UniversityNantong 226019JiangsuPeople’s Republic of China

Two-dimensional black phosphorus(2D BP),well known as phosphorene,has triggered tremendous attention since the first discovery in *** unique puckered monolayer structure endows 2D BP intriguing properties,which facilitate its potential applications in various fields,such as catalyst,energy storage,sensor,*** to the large surface area,good electric conductivity,and high theoretical specific capacity,2D BP has been widely studied as electrode materials and significantly enhanced the performance of energy storage *** the rapid development of energy storage devices based on 2D BP,a timely review on this topic is in demand to further extend the application of 2D BP in energy *** this review,recent advances in experimental and theoretical development of 2D BP are presented along with its structures,properties,and synthetic ***,their emerging applications in electrochemical energy storage,including Li−/K−/Mg−/Na-ion,Li–S batteries,and supercapacitors,are systematically summarized with milestones as well as the *** from the fast-growing dynamic investigation of 2D BP,some possible improvements and constructive perspectives are provided to guide the design of 2D BP-based energy storage devices with high performance.

关键词： 2D black phosphorus Electronic structure Supercapacitors Batteries

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Multiple α sub-variants and anisotropic mechanical properties of an additively-manufactured Ti-6Al-4V alloy

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Journal of Materials Science & Technology 2021年第11期70卷 113-124页

作者： Yinling Zhang Zhuo Chen Shoujiang Qu Aihan Feng Guangbao Mi Jun Shen Xu Huang Daolun Chen School of Materials Science and Engineering Tongji UniversityShanghai 201804China Department of Mechanical and Industrial Engineering Ryerson UniversityTorontoOntario M5B 2K3Canada Aerospace Hiwing(Harbin)Titanium Industrial Co. Ltd.Harbin High Tech ZoneHarbin 150028China Shanghai Key Lab.of D&A for Metal-Functional Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China

Additive manu facturing(AM)is a promising material processing method which gains significant momentum in the aerospace and biomedical ***,the anisotropy in the mechanical properties of additively-manufactured materials is still poorly *** study was aimed at elucidating crystallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundantαlamellae with six variants were present inside the columnar prior-βgrains with a<100>fiber texture duringβ→αphase *** sixαvariants followed the Burgers orientation relationship of{110}_(β)//{0001}_(α)and<1-11>_(β)//<11-20>_(α).Multiple sub-variants in eachαvariant were observed for the first *** anisotropy in the mechanical properties was mainly related to the relative amount of sixα*** the horizontally-oriented samples had a lower yield strength,they exhibited a higher ductility and longer fatigue life than the vertically-oriented *** softening occurred at higher strain amplitudes,and cyclic stabilization sustained at lower strain *** crack mainly initiated from the specimen surface at lower strain amplitudes,while multiple crack initiation tended to occur at higher strain *** propagation was characterized by fatigue striations along with some secondary cracks.

关键词： Titanium alloy 3D printing Deformation behavior Anisotropy Burgers orientation relationship

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Fault-tolerant localization for multi-UAV cooperative flight

Fault-tolerant localization for multi-UAV cooperative flight

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2010 IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications, MESA 2010

作者： Qu, Yaohong Zhang, Youmin Dept. of Mechanical and Industrial Engineering Concordia University Montreal H3G 2 W1 Canada School of Automation Northwestern Polytechnical University Xi'an 710072 China Dept. of Mechanical and Industrial Engineering Diagnosis Flight Control and Simulation Lab Concordia University Montreal H3G 2 W1 Canada

ISBN: (纸本)9781424471010

A novel fault-tolerant localization method for low-cost UAVs flying at constant altitude is proposed in this paper, which is based on measuring relative ranges from one UAV to other UAVs. Contrast to the traditional navigation methods of single aerial vehicle, like INS/GPS and SINS/GPS, the proposed method is more suitable for low-cost small-size UAVs because of its low requirement to the navigation device. Furthermore, its localization accuracy is higher than other methods for multi-UAV because the sharable information in multi-UAV network is made full of use. Similar to the principle of GPS, the method takes three other UAVs as the reference points of an UAV whose GPS receiver works improperly due to failure. Thus the UAV's location in 2D horizontal plane can be determined by using the relative ranges from the faulty UAV to the other three UAVs at known location in inertial coordinate system. In order to improve the accuracy of estimated location, a Kalman filter is designed, which can calculate the variance of observations in terms of horizontal dilution of positioning (HDOP) adaptively. Meanwhile, option of the reference points is also optimized in the paper. Simulation results in Matlab\Simulink show the effectiveness of the proposed approach. © 2010 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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Vision-Based Dexterous Motion Planning by Dynamic Movement Primitives with Human Hand Demonstration

arXiv

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arXiv 2024年

作者： Chen, Nuo Pan, Ya-Jun The Advanced Control and Mechatronics Lab Department of Mechanical Engineering Dalhousie University HalifaxB3H 4R2 Canada

This paper proposes a vision-based framework for a 7-degree-of-freedom robotic manipulator, with the primary objective of facilitating its capacity to acquire information from human hand demonstrations for the execution of dexterous pick- and-place tasks. Most existing works only focus on the position demonstration without considering the orientations. In this paper, by employing a single depth camera, MediaPipe is applied to generate the three-dimensional coordinates of a human hand, thereby comprehensively recording the hand’s motion, encompassing the trajectory of the wrist, orientation of the hand, and the grasp motion. A mean filter is applied during data pre-processing to smooth the raw data. The demonstration is designed to pick up an object at a specific angle, navigate around obstacles in its path and subsequently, deposit it within a sloped container. The robotic system demonstrates its learning capabilities, facilitated by the implementation of Dynamic Movement Primitives, enabling the assimilation of user actions into its trajectories with different start and end points. Experimental studies are carried out to demonstrate the effectiveness of the work. Copyright © 2024, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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An experimental study of ultrasonic tip clearance sensor 34th

An experimental study of ultrasonic tip clearance sensor

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34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 1998

作者： Tagashira, Takeshi Sugiyama, Nanahisa Matsuda, Yukio Matsukt, Masakatsu Engine Control Lab Aeroengine Division National Aerospace Laboratory 7-44-1 Jindaiji-Higashi Chofu Tokyo182-8522 Japan Department of Mechanical Engineering Nippon Institute of Technology 4-1 Miyashiro Minami-SaitamaSaitama345-8501 Japan

This paper describes a development and evaluation of a blade tip clearance measurement system using an ultrasonic sensor. The method developed here has some advantages;(i) adequate for non-metal blade;(ii) measurement without contact;(iii) operable in dirty environment;(iv) easy to install;and (v) digital measurement suitable to an advanced control. Experimental results using a rotating blade test rig are described. Blade tip speed is restricted to Mach 0.96 due to the limitation of the test rig. It is concluded that the ultrasonic method is a promising candidate for an on-line clearance control of gas turbine engines. © 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Gas turbines

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Bidirectional Multi-Stack RNNs with Attention for Machine Translation

Bidirectional Multi-Stack RNNs with Attention for Machine Tr...

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On-Line Conference (ONCON), Industrial Electronics Society Annual

作者： Zhiren Chen Ziyu Qiu Nuo Chen the Department of Mechanical & Industrial Engineering University of Toronto Toronto Canada Faculty of Computer Science Dalhousie University Halifax Canada Department of Mechanical Engineering Advanced Control and Mechatronics Lab Dalhousie University Halifax Canada

This project developed a novel attention algorithm for multi-stack bidirectional encoder-decoder RNN (including GRU and LSTM) sequence-to-sequence models, particularly for language translation tasks. The attention mechanism utilizes matrix rearranging and multiplication to compute the significance of the vectors in the encoder output to the vectors in the current decoder hidden states when predicting each word. Our approach achieved 98% of the performance of fine-tuned pretrained T5-small, with 30% to 50% fewer parameters depending on vocabulary size, making our model an ideal choice in cases of single-processor training, low processor resource, limited memory, small dataset, or tasks not supported by pretrained transformers.

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