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The temperature field study on the annular heat source model in large surface grinding by cup wheel

INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2017年第9-12期93卷 3261-3273页

作者： Wang, Ruiqin Dai, Shijie Zhang, Huibo Dong, Yafan Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interac Tianjin 300132 Peoples R China

Most of the current studies focus on the moving heat source model of straight wheel. However, these cannot be applied to calculate the cup wheel grinding temperature field, especially for the grinding processes performed with an adaptive end-effector. Based on the moving heat method and the principle of heat source superposition, the analytical thermal model of annular moving heat source for large surface workpiece is deduced. According to the parameters of the grinding instance, the numerical model is established by the finite element method for comparison and validating in this paper. The comparison results show that the characteristics of temperature distribution predicted by the analytical model and the numerical model agree very well. Two evident peak temperatures in grinding zone appear at both edges at the back of the grinding wheel in the feed direction, and test results with different grinding parameters show the relative errors do not exceed 19%. The feasibility of the analytical model and the numerical model based on different mathematical foundations is mutually validated. In the view of the non-uniform features of temperature distribution, especially the location of the peak temperature values, there are some reasonable explanations and analyses in this paper.

关键词： Surface grinding Moving heat source model Cup wheel Analytical thermal model Finite element method Temperature field

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A low cost and portable smartphone microscopic device for cell counting

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SENSORS AND ACTUATORS A-PHYSICAL 2018年 274卷 57-63页

作者： Zeng, Yujin Jin, Ke Li, Jie Liu, Jixiao Li, Junwei Li, Tiejun Li, Shanshan Hebei Univ Technol Sch Mech Engn Tianjin 300130 Peoples R China Hebei Key Lab Smart Sensing & Human Robot Interac Tianjin 300401 Peoples R China Hebei Univ Technol Sch Architecture & Design Tianjin 300401 Peoples R China Hebei Univ Technol Inst Biophys Tianjin 300401 Peoples R China

Portable smartphone microscopic devices can potentially address various imaging and cell counting needs in healthcare monitoring. In this paper, a portable microscopic platform is constructed by a commercial smartphone and a custom-designed slider-scale microfluidic chip. Here the smartphone acts both as a detector and image analysis station. We demonstrate the adaptation of a smartphone's camera by loading a single-ball lens to function as a compact microscope, and then a glass slider or a slider-scale multiplex microfluidic chip is designed for preprocess of the samples. Our portable imaging device allows for micron size resolution and a home-coded Android application is performed for automatic/manual particle counting. Pumpkin pollen powders on a slider were counted as a demo test and then the counting for dairy somatic cells within a microfluidic chip were carried out automatically. The results from the smartphone microscopic device show good agreement with those values done by commercial microscope and flowcytometry. With advances in miniaturized electronics and smartphones, this low cost and portable smartphone microscopic platform can be used as common and convenient tools to perform true point-of-care biomedical or biochemical lab-on-a-chip applications. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Microscopic Smartp hone Portable Cell counting Low cost

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Dynamic positioning accuracy of dual-axis drive mechanism of satellite antenna with multi-clearance coupling

Dynamic positioning accuracy of dual-axis drive mechanism of...

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Asia Conference on Mechanical Engineering and Aerospace Engineering (MEAE)

作者： Qi, Chaoqun Zhang, Huibo You, Bindi Fan, Jizhuang Dai, Shijie Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interac Tianjin 300130 Peoples R China Harbin Inst Technol Weihai Sch Naval Architecture & Ocean Engn Weihai 264209 Shandong Peoples R China Harbin Inst Technol State Key Lab Robot & Syst Harbin 150001 Heilongjiang Peoples R China

The dual-axis drive mechanism of satellite antenna as a typical multi joint aerospace mechanism consists of azimuth axis and pitch axis. The multi-clearance contained within those drive joint cause contact and impact in joint, and consequently affect the dynamic positioning accuracy. A nonlinear dynamic model of planetary gears with multiple clearances couplings is proposed to investigate the influence mechanism of clearances on the dynamic performances. The nonlinear factors such as radial clearance, backlash and time-varying meshing stiffness of the bearing are considered in the model. And the dynamic model of double-axis driving mechanism of satellite antenna with multi-clearance coupling is established. Then positional and rotational speed error curves of antenna reflector at different rotational speed are respectively analyzed. The numerical simulation results show that the influence of multi-clearance coupling on the dynamic positioning accuracy of double-axis drive mechanism of satellite antenna is remarkable.

关键词： Satellite antennas

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Biomimetic Design of A Chest Carrying Nursing-care robot for Transfer Task

Biomimetic Design of A Chest Carrying Nursing-care Robot for...

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IEEE International Conference on robotics and Biomimetics (ROBIO)

作者： Liu, Yuxin Chen, Guiliang Liu, Jinyue Guo, Shijie Mukai, Toshiharu Hebei Key Lab Robot Sensing & Human Robot Interac State Key Lab Reliabil & Intelligence Elect Equip Tianjin Peoples R China Hebei Univ Technol Tianjin Peoples R China RIKEN 2-1 Hirosawa Wako Saitama 3510198 Japan Meijo Univ Tempaku Ku 1-501 Shiogamaguchi Nagoya Aichi 4688502 Japan

ISBN: (纸本)9781728103778

Patient transfer, such as lifting and moving a bedridden patient from a bed to a wheelchair or a pedestal pan and back, is one of the most physically challenging tasks in nursing care. We have developed a prototype nursing-care assistant robot that can conduct patient transfer by imitating the motion when a person holds another person on his/her back. Based on the measurement of human motions including back-chest touching, leaning forward, holding up, moving and putting down, we analyzed the key factors that may influence the safety and comfort of the patient and designed a new type of robot. The robot consists of a chest holder which moves like a human back. In this paper, we state the details of motion design and related kinematic/dynamic analysis of the robot and demonstrate its effect on patient transfer. It is demonstrated that the robot developed can transfer a subject from a bed to a chair and back.

关键词： Machine design

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Pressure-Driven Micro-Casting for Electrode Fabrication and Its Applications in Wear Grain Detections

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MATERIALS 2019年第22期12卷 3710页

作者： Cheng, E. Xing, Ben Li, Shanshan Yu, Chengzhuang Li, Junwei Wei, Chunyang Cheng, Cheng Hebei Univ Technol Sch Mech Engn Tianjin 300132 Peoples R China Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equip Tianjin 300130 Peoples R China Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interac Tianjin 300132 Peoples R China Hebei Univ Technol Dept Comp Sci & Elect Engn Langfang 065000 Peoples R China Hebei Univ Technol Sch Sci Inst Biophys Tianjin 300401 Peoples R China Morehead State Univ Sch Engn & Comp Sci Morehead KY 40351 USA

The microelectrode is an essential and vital part in microsensors that are largely used in industrial, chemical, and biological applications. To obtain desired microelectrodes in great quality, it is also of great necessity and significance to develop a robust method to fabricate the microelectrode pattern. This work developed a four-terminal differential microelectrode that aims at recognizing microparticles in fluids. This microelectrode pair consisted of a high height-width ratio microelectrode array fabricated using a pre-designed microelectrode pattern (a micro-scale channel) and melted liquid metal. The surface treatment of microelectrodes was also investigated to reveal its impacts on the continuality of melting metal and the quality of the fabricated microelectrode patterns. To evaluate the performance of micro-casting fabricated electrodes, a microfluidic device was packaged using a microelectrode layer and a flow layer. Then impedance cytometer experiments were performed using sample fluids with polymer particles in two different sizes in diameter (5 mu m and 10 mu m). In addition, engine oil was tested on the microelectrodes as complex samples. The number of abrasive particles in the engine oil can be collected from the developed microfluidic device for further analysis.

关键词： microfabrication melting metal surface pretreatment impedance cytometer differential amplifier wear particle detection

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Easy-to-operate fabrication of tapered glass capillaries for microdroplet generation

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JOURNAL OF MICROMECHANICS AND MICROENGINEERING 2019年第3期29卷 037001-037001页

作者： Wei, Chunyang Yu, Chengzhuang Wu, Jie Jayne Li, Junwei Li, Shanshan Dai, Shijie Li, Tiejun Hebei Univ Technol Sch Mech Engn Tianjin 300401 Peoples R China Hebei Key Lab Smart Sensing & Human Robot Interac Tianjin 300130 Peoples R China Univ Tennessee Dept Elect Engn & Comp Sci Knoxville TN 37996 USA Hebei Univ Technol Dept Comp Sci & Elect Engn Langfang 000650 Peoples R China State Key Lab Reliabil & Intelligence Elect Equip Tianjin 300132 Peoples R China

Tapered glass capillaries play an important role in microdroplet generation and related microfluidic applications such as particle synthesis, digital PCR and microrectors. However, its controlled production poses a challenge. Specifically, there is difficulty controlling the tip sizes of capillaries with good repeatability at an affordable cost, which is critical to produce standard droplets for use by research groups. To produce tapered capillaries, micro needle geometries are first pulled by a commercial pipette puller, which yields a sharp tip (i.e. 1-3 mu m). Those tips need to be enlarged and standardized by post microfabrication. Although larger tips could be achieved by advanced pulling-forging, sanding-forging or breakingforging methods, the uniformity and repeatability do not meet the requirements for mass production. In this paper, several easy-to-operate fabrication approaches, including mechanical and chemical fabrication methods, are studied. Chemical etching fabrication method shows good repeatability and robust control of dimensions. A capillary droplet microfluidic device assembled by tapered glass capillaries fabricated by chemical etching method is also presented, which shows good performance for droplet generations. This non-labor intensive fabrication is straightforward and be readily adopted for industrial scale mass production.

关键词： micro fabrication glass capillary taper droplet generation

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AC electrothermal mixing for high conductive biofluids by arc-electrodes

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JOURNAL OF MICROMECHANICS AND MICROENGINEERING 2018年第6期28卷 065004-065004页

作者： Meng, Jiyu Li, Shanshan Li, Junwei Yu, Chengzhuang Wei, Chunyang Dai, Shijie Hebei Univ Technol Sch Mech Engn Tianjin 300130 Peoples R China Hebei Key Lab Robot Sensing & Human Robot Interac Tianjin 300130 Peoples R China Hebei Univ Technol Inst Biophys Tianjin 300401 Peoples R China

As a platform to mix the bioagents (i.e. serum, urine), we take advantage of the alternating current electrothermal (ACET) effect which is quite suitable for rapid pumping/mixing of high conductive biomicrofluids. Here we demonstrate the concept of a high-efficient mixing microfluidic chip as a basic unit to provide rapid mixing for lab-on-a-chip applications. As an active mixer, two streams are introduced into a ring-shape microchamber by a passive flow rate regulator, and then the microfluids in the chamber are actuated by a nonuniform electric field with a phase shift of 180 degrees. It shows perfect mixing performance by arranging four arc-electrodes around the ring-shape microchamber subsequently. Taking the Joule heating and conductivity/permittivity changes into consideration, a temperature dependent fully coupled numerical model is presented. Then, the effects of applied voltages on mixing performance and temperature rise are provided to get an optimized design for ACET mixer. Moreover, the arrangement of the electrode array is analyzed to show the effects of electrode patterns on the swirls and mixing efficiencies. Since all the electrodes here are located along a ring-shape central microchamber, the ring-shape micromixer is quite suitable to function as a compact element modular for integrated microfluidic chips.

关键词： AC electrothermal mixing ring-shape arc-electrodes fully-coupled

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Stretchable, ultrasensitive, and low-temperature NO2 sensors based on MoS2@rGO nanocomposites

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MATERIALS TODAY PHYSICS 2020年 15卷

作者： Yi, Ning Cheng, Zheng Li, Han Yang, Li Zhu, Jia Zheng, Xiaoqi Chen, Yong Liu, Zhendong Zhu, Hongli Cheng, Huanyu Penn State Univ Dept Mat Sci & Engn University Pk PA 16802 USA Penn State Univ Mat Res Inst University Pk PA 16802 USA Northeastern Univ Dept Mech & Ind Engn Boston MA 02115 USA Penn State Univ Dept Engn Sci & Mech 227 Hammond Bldg University Pk PA 16802 USA Xiamen Univ Pen Tung Sah Inst Micronano Sci & Technol Xiamen 361005 Fujian Peoples R China Southeast Inst Chinaunicom Fuzhou 350000 Fujian Peoples R China Hebei Univ Technol Sch Mech Engn Hebei Key Lab Robot Percept & Human Robot Interac Tianjin 300401 Peoples R China ShanghaiTech Univ Sch Phys Sci & Technol Shanghai 201219 Peoples R China Zhejiang Univ Technol Minist Educ & Zhejiang Prov Hangzhou 310014 Zhejiang Peoples R China

The recent development of 3D highly porous laser-induced graphene (LIG) has drawn significant attention for numerous sensing applications. In particular, novel gas sensing platforms based on stretchable LIG patterns with self-heating capabilities have been demonstrated as a simple alternative to interdigitated electrodes (IDEs) for integrating gas-sensitive nanomaterials. However, their direct performance comparison with the IDEs is unclear. In this paper, the sensing performance of nanomaterials with various specific surface areas between the LIG patterns and IDEs are compared directly. Molybdenum disulfide (MoS2) @ reduced graphene oxide (rGO) was synthesized with controllable size and morphology for nitrogen dioxide (NO2) sensing. When dispersing MoS2@rGO on an IDE integrated on a soft silicone polymeric substrate, the stretchable gas sensor exhibited mechanical robustness upon stretching and a significantly large signal-to-noise ratio (SNR) for rapid detection of 10 ppb NO2. The MoS2@rGO nanocomposite was integrated on a stretchable 3D porous LIG pattern yielding an extraordinarily high SNR of 1026.9 to NO2 of 2 ppm. Considering the high SNR of over 60 to NO2 of 10 ppb, the novel LIG gas sensing platform with a simple fabrication process shows a great promise to test nanomaterials and enable stretchable bio-integrated gas sensors for monitoring of the health and environment. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： Molybdenum disulfide (MoS2) Reduced graphene oxide (rGO) Nitrogen dioxide (NO2) Stretchable and ultrasensitive Laser-induced graphene (LIG) patterns

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Vibration Characteristics Analysis of Planetary Gears with a Multi-Clearance Coupling in Space Mechanism

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ENERGIES 2018年第10期11卷 2687-2687页

作者： Zhang, Huibo Qi, Chaoqun Fan, Jizhuang Dai, Shijie You, Bindi Hebei Univ Technol Sch Mech Engn Tianjin 300130 Peoples R China Hebei Key Lab Robot Percept & Human Robot Interac Tianjin 300130 Peoples R China Harbin Inst Technol State Key Lab Robot & Syst Harbin 150080 Heilongjiang Peoples R China Harbin Inst Technol Weihai Sch Naval Architecture & Ocean Engn Weihai 264209 Peoples R China

Multi-clearance is the main cause for the performance and reliability decline of complicated mechanical systems. The increased clearance could induce contacts and impacts in joints, and consequently affect control accuracy. A nonlinear dynamic model of planetary gears with multi-clearance coupling is proposed in the current study to investigate the mechanism of influence of clearance on the dynamic performance. In addition, the coupling relationship between radial clearance and backlash is integrated into the multi-body system dynamics. The vibration characteristics of planetary gears with the changes of rotational velocity, clearance size and inertia load are explored. The numerical simulation results show that there are complex coupling relations in planetary gear systems, due to the multi-clearance coupling. The phenomenon of system resonance may occur with the changes of rotational velocities and clearances' sizes. Multi-clearance coupling can significantly increase the resonant response of planetary gear systems in empty-load or light-load states.

关键词： space mechanism multi-clearance nonlinear dynamic model planetary gears vibration characteristics

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Fluid mixing in droplet-based microfluidics with T junction and convergent-divergent sinusoidal microchannels

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ELECTROPHORESIS 2018年第3期39卷 512-520页

作者： Yang, Li Li, Shanshan Liu, Jixiao Cheng, Jingmeng Hebei Key Lab Smart Sensing & Human Robot Intera Tianjin Peoples R China Hebei Univ Technol Sch Mech Engn Tianjin Peoples R China

To explore and utilize the advantages of droplet-based microfluidics, hydrodynamics, and mixing process within droplets traveling though the T junction channel and convergent-divergent sinusoidal microchannels are studied by numerical simulations and experiments, respectively. In the T junction channel, the mixing efficiency is significantly influenced by the twirling effect, which controls the initial distributions of the mixture during the droplet formation stage. Therefore, the internal recirculating flow can create a convection mechanism, thus improving mixing. The twirling effect is noticeably influenced by the velocityof thecontinuous phase;in the sinusoidal channel, the Dean vortices and droplet deformation are induced by centrifugal force and alternative velocity gradient, thus enhancing the mixing efficiency. The best mixing occurred when the droplet size is comparable with the channel width. Finally, we propose a unique optimized structure, which includes a T junction inlet joined to a sinusoidal channel. In this structure, the mixing of fluids in the droplets follows two routes: One is the twirling effect and symmetric recirculation flow in the straight channel. The other is the asymmetric recirculation and droplet deformation in the winding and variable cross-section. Among the three structures, the optimized structure has the best mixing efficiency at the shortest mixing time (0.25 ms). The combination of the twirling effect, variable cross-section effect, and Dean vortices greatly intensifies the chaotic flow. This study provides the insight of the mixing process and may benefit the design and operations of droplet-based microfluidics.

关键词： Dean vortices Microdroplet Mixing Twirling effect

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