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Experimental and numerical research on the characteristics of heavy gas leakage and diffusion

PROCESS SAFETY PROGRESS 2022年第3期41卷 567-580页

作者： Shi, Bao-Jun Wang, Hui Nie, Shi-Ming Cheng, Cheng Li, Tie-Jun Hebei Univ Technol Sch Mech Engn Tianjin 300401 Peoples R China State Key Lab Reliabil & Intelligence Elect Equip Tianjin Peoples R China Hebei Key Lab Robot Sensing & Human Robot Integra Tianjin Peoples R China

Once a hazardous gas leaks, it will pose a serious threat to the safety of people's lives and property. This paper aims to investigate the flow characteristics of heavy gas leakage and diffusion to deal with sudden accidents caused by hazardous gas leakage. First, an experimental platform for the leakage and diffusion of heavy gas is built, and the tracer technique is adopted to visualize the experimental phenomena during the process of gas leakage and diffusion. Second, a computational fluid dynamics (CFD) model is built based on the experimental platform to simulate and analyze the gas leakage and diffusion process. The CFD model is verified by comparing the numerical results with those of experiments using an authoritative evaluation standard procedure. The comparison shows that the related statistical performance measures are all reasonable. Third, a three-dimensional numerical model of a real tank farm is created in full scale and the heavy gas (liquefied petroleum gas) leakage process is simulated and analyzed considering also the effect of wind. Experimental and numerical results show that the heavy gas leakage and diffusion process can be divided into three stages: gas concentration rising stage, gravity sedimentation stage, and gas passive diffusion stage, in which different flow phenomena are observed with different flow characteristics for each of the stages. The phenomena observed in experiment are further analyzed and clarified using fluid dynamics by numerical simulation. The full-scale modeling and simulation of the real tank farm is helpful for taking possible measures once a gas leakage occurs.

关键词： computational fluid dynamics design and simulation evacuation route heavy gas leakage and diffusion

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Flexible and Antifreezing Fiber-Shaped Solid-State Zinc-Ion Batteries with an Integrated Bonding Structure

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JOURNAL OF PHYSICAL CHEMISTRY LETTERS 2023年第14期14卷 3512-3520页

作者： Wang, Guo-Yuan Li, Guo-Xian Tang, Yu-Dong Zhao, Zhen Yu, Wei Meng, Chui-Zhou Guo, Shi-Jie Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equipm Tianjin 300401 Peoples R China Hebei Univ Technol Hebei Key Lab Smart Sensing & Human Robot Interact Tianjin 300401 Peoples R China Hebei Univ Technol Sch Mech Engn Tianjin 300401 Peoples R China

Fiber-shaped solid-state zinc-ion battery (FZIB) is a promising candidate for wearable electronic devices, but challenges remain in terms of mechanical stability and low temperature tolerance. Herein, we design and fabricate a FZIB with an integrated device structure through effective incorporation of the active electrode materials with a carbon fiber rope (CFR) and a gel polymer electrolyte. The gel polymer electrolyte incorporated with ethylene glycol (EG) and graphene oxide (GO) endows the FZIB with a high Zn stripping/ plating efficiency under extreme low temperature conditions. A high power density of 1.25 mW cm-1 and large energy density of 0.1752 mWh cm-1 are obtained. In addition, a high capacity retention of 91% after 2000 continuous bending cycles is achieved. Furthermore, the discharge capacity is fairly retained at more than 22% even at the low temperature of -20 degrees C. Toward practical applications, the FZIB integrated into textiles to power electronic products is demonstrated.

关键词： Mechanical stability

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A highly stretchable and ultra-sensitive strain sensing fiber based on a porous core-network sheath configuration for wearable human motion detection

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NANOSCALE 2022年第34期14卷 12418-12430页

作者： Liu, Jun Wang, Peng Li, Guoxian Yang, Li Yu, Wei Meng, Chuizhou Guo, Shijie Hebei Univ Technol Sch Mech Engn State Key Lab Reliabil & Intelligence Elect Equip Hebei Key Lab Smart Sensing & Human Robot Interac Tianjin 300401 Peoples R China Hebei Univ Technol Sch Hlth Sci & Biomed Engn State Key Lab Reliabil & Intelligence Elect Equip Tianjin 300130 Peoples R China

Functional fibers have attracted much research attention due to their potential application in developing advanced electronic textiles for wearable devices. However, challenges still exist in preparing high-performance fiber-shaped sensors with superior flexibility and stretchability while achieving a high sensitivity and a wide detection range. Herein, we propose the design and fabrication of an ultra-flexible and super-elastic fiber-shaped strain sensor via a facile combining approach of wet-spinning and dip-coating. The sensor adopts a core-sheath configuration of liquid metal droplets dispersed in porous thermoplastic polyurethane as a substrate core and a carbon nanotube intertwined network embedding silver nanowires as a strain sensitive sheath. By taking advantage of both the composition of multiple functional materials and the design of a microstructured device configuration, the developed fiber-shaped sensor exhibits an ultrahigh sensitivity (maximum gauge factor of 7336.1), an extremely large workable strain range (500%), a low strain detection limit (0.5%), a fast response time (200 ms) and good stability (10 000 cycles). In addition, the sensor is temperature insensitive, inert under harsh solution conditions, degradable and recyclable. Intriguingly, the fiber-shaped sensor can be used to detect various human motions and gestures by directly attaching to skins or elaborately weaving into textiles, demonstrating its great potential in human healthcare monitoring and human-machine interactions.

关键词： Fibers

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Copper-cobalt diatomic bifunctional oxygen electrocatalysts based on three-dimensional porous nitrogen-doped carbon frameworks for high-performance zinc-air batteries

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2025年第Pt 1期683卷 1150-1161页

作者： Ma, Zhaolei Bai, Ruoning Yu, Wei Li, Guoxian Meng, Chuizhou Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equipm Tianjin 300401 Peoples R China Hebei Univ Technol Engn Res Ctr Minist Educ Intelligent Rehabil Devic Tianjin 300401 Peoples R China Hebei Univ Technol Hebei Key Lab Smart Sensing & Human Robot Interact Tianjin 300401 Peoples R China Hebei Univ Technol Sch Mech Engn 5340 Xiping Rd Tianjin 300401 Peoples R China

Transition-metal-loaded carbon-based electrocatalysts are promising alternatives to conventional precious metal electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in highperformance zinc-air batteries. However, efficiently doping transition-metal single atoms onto carbon-based frameworks is a significant challenge. Herein, an improved template-sacrificing method combining a two-step carbonization process is proposed to fabricate Cu/Co diatomic sites coanchored on a three-dimensional nitrogen-doped carbon-based framework. By optimizing the addition amounts of silica (template) and zinc chloride (foaming agent), as well as adjusting the high-temperature treatment conditions, the porous microstructure of the nitrogen-carbon framework is fine-tuned to achieve the optimal diatomic Cu/Co loading. This catalyst exhibits excellent bifunctional oxygen electrocatalytic performance, facilitating both ORR and OER, and out- performing commercial precious metal electrocatalysts. The synergistic catalytic effect of the isolated dual-metal sites for high-performance electrocatalysis of ORR and OER is thoroughly investigated through comparative studies with nitrogen-doped carbon frameworks without Cu or Co. An aqueous zinc-air battery is assembled to demonstrate its exceptional performance, including a high open-circuit voltage of 1.48 V, a high peak power density of 311 mW cm- 2 , and remarkable durability, exceeding 600 h. Additionally, a zinc-air battery containing a gel-polymer electrolyte is assembled to showcase its potential application in wearable electronic devices.

关键词： Zinc-air battery Copper-cobalt diatomic site Porous nitrogen-doped carbon framework Oxygen reduction reaction Oxygen evolution reaction

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Design and Compliant Control of a Piggyback Transfer robot

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JOURNAL OF MECHANISMS AND robotICS-TRANSACTIONS OF THE ASME 2022年第3期14卷 031009页

作者： Liu, Yuxin Guo, Shijie Yin, Yuting Jiang, Zhiwen Liu, Teng Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equip 81 Dingzigu Rd Tianjin 300131 Peoples R China Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interac 81 Dingzigu Rd Tianjin 300131 Peoples R China Hebei Univ Technol Sch Mech Engn 81 Dingzigu Rd Tianjin 300131 Peoples R China

Patient transfer, such as lifting and moving a bedridden patient from a bed to a wheelchair or a pedestal pan, is one of the most physically challenging tasks in nursing care. Although many transfer devices have been developed, they are rarely used because of the large time consumption in performing transfer tasks and the lack of safety and comfortableness. We developed a piggyback transfer robot that can conduct patient transfer by imitating the motion when a person holds another person on his/her back. The robot consisted of a chest holder that moves like a human back. In this paper, we present an active stiffness control approach for the motion control of the chest holder, combined with a passive cushion, for lifting a care-receiver comfortably. A human-robot dynamic model was built and a subjective evaluation was conducted to optimize the parameters of both the active stiffness control and the passive cushion of the chest holder. The test results of 10 subjects demonstrated that the robot could transfer a subject safely, and the combination of active stiffness and passive stiffness were essential to a comfortable transfer. The objective evaluation demonstrated that an active stiffness of k = 4 kPa/mm along with a passive stiffness lower than the stiffness of human chest was helpful for a comfort feeling.

关键词： nursing care robot transfer task bio-inspired design compliant control care-receiver's comfort

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Easy-to-Operate Co-flow Step Emulsification Device for Droplet Digital Polymerase Chain Reaction

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ANALYTICAL CHEMISTRY 2022年第9期94卷 3939-3947页

作者： Wei, Chunyang Yu, Chengzhuang Li, Shanshan Meng, Jiyu Li, Tiejun Cheng, Jingmeng Pan, Feng Li, Junwei Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interac 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 Inst Biophys Sch Hlth Sci & Biomed Engn Tianjin 300401 Peoples R China Hebei Univ Technol Dept Elect & Informat Engn Langfang 065000 Peoples R China

Digital polymerase chain reaction (PCR) plays important roles in the detection and quantification of nucleic acid targets, while there still remain challenges including high cost, complex operation, and low integration of the instrumental system. Here, in this work, a novel microfluidic chip based on co-flow step emulsification is proposed for droplet digital PCR (ddPCR), which can achieve droplet generation, droplet array self-assembly, PCR amplification, and fluorescence detection on a single device. With the combination of single-layer lithography and punching operation, a step microstructure was constructed and it served as the key element to develop a Laplace pressure gradient at the Rayleigh-Plateau instability interface so as to achieve droplet generation. It is demonstrated that the fabrication of step microstructure is low cost, easy-to-operate, and reliable. In addition, the single droplet volume can be adjusted flexibly due to the co-flow design;thus, the ddPCR chip can get an ultrahigh upper limit of quantification to deal with DNA templates with high concentrations. Furthermore, the volume fraction of the resulting droplets in this ddPCR chip can be up to 72% and it results in closely spaced droplet arrays, makes the best of CCD camera for fluorescence detections, and is beneficial for the minimization of a ddPCR system. The quantitative capability of the ddPCR chip was evaluated by measuring template DNA at concentrations from 20 to 50 000 copies/mu L. Owing to the characteristics of low cost, easy operation, excellent quantitative capability, and minimization, the proposed ddPCR chip meets the requirements of DNA molecule quantification and is expected to be applied in the point-of-care testing field.

关键词： lab-on-a-chip Microfluidics

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Force Tracking Control With Adaptive Stiffness and Iterative Position of Hip-Assistive Soft Exosuits

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IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING 2024年第4期21卷 7203-7218页

作者： Chen, Qiang Guo, Shijie Zhang, Dan Hebei Univ Technol Hebei Key Lab Robot Sensing & Human Robot Interact Sch Mech Engn Engn Res CtrMinist Educ Intelligent Rehabil Equip Tianjin 300401 Peoples R China York Univ Dept Mech Engn Toronto ON M3J 1P3 Canada Fudan Univ Inst Robot & AI Shanghai 200433 Peoples R China York Univ Dept Mech Engn Toronto ON M3J 1P3 Canada

Soft exosuits feature nonlinear, low stiffness, and hysteretic behavior, presenting different mechanical responses during loading and unloading of assistive force. Delivering the desired force to the wearer is a challenge in such a system. To address this issue, this article proposed a novel control strategy with adaptive stiffness and iterative position to optimize the assistive forces of the actuators in compliance with the humanexosuit interface stiffness and relative motion. Specifically, a stiffness model was proposed to describe the force loading and unloading behaviors, further an adaptive stiffness-based force controller was designed to improve the force tracking for whole profile by adaptively adjusting the stiffness parameters related to loading and unloading, and iteratively compensating the position error associated with the force amplitude in the model on a step-by-step basis. This control strategy was implemented on a soft exosuit for hip flexion and extension assistance, and its performance was evaluated through walking tests on six subjects. The results showed that after 4 or 5 iterations of optimization based on the initial parameter settings, the proposed controller could comply with the human-exosuit interface stiffness and achieved an improved force tracking, with a minimal root-mean-square error of 7.5 N in desired force profiles tracking, and a metabolic gain of 14.8%, demonstrating a promising potential of the proposed controller for improving the force tracking and the economy of human walking.

关键词： Soft exosuits hip assistance force tracking adaptive stiffness control iterative optimization

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Observer-based finite-time control for trajectory tracking of lower extremity exoskeleton

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART I-JOURNAL OF SYSTEMS AND CONTROL ENGINEERING 2022年第2期236卷 257-269页

作者： Wang, Jie Liu, Jiahao Chen, Lingling Guo, Shijie Univ Sci & Technol Beijing Inst Artificial Intelligence Beijing Peoples R China Hebei Univ Technol Sch Artificial Intelligence & Data Sci Guangrong Rd Tianjin 300130 Peoples R China Engn Res Ctr Intelligent Rehabil Minist Educ Tianjin Peoples R China Hebei Key Lab Robot Sensing & Human Robot Interac Tianjin Peoples R China

In this article, an advanced observer-based finite-time trajectory tracking controller is investigated for lower extremity exoskeleton without available joint angular velocities to improve the movement ability of dependent persons, which is robust against uncertain dynamics, human active joint torque and external disturbances. First, the Lagrange principle is applied to analyze the dynamic properties of lower extremity exoskeleton driven by artificial pneumatic muscles, and its swing phase model is established. After that, a novel finite-time extended state observer is proposed to observe the lumped disturbances and unavailable angular velocities of the lower limb exoskeleton simultaneously. Furthermore, a finite-time sliding mode controller of exoskeleton is designed based on the extended state observer, and the finite-time convergence of tracking error is rigorously demonstrated based on the Lyapunov theory. Finally, the control system simulation is established and experimental tests are conducted with a voluntary subject during flexion of wearer's knee and hip joints, the obtained results demonstrate fast and high-precision tracking performance of the proposed approach.

关键词： Lower extremity exoskeleton sliding mode control finite-time control Lyapunov theory extended state observer

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All-Gel-Based Triboelectric Noncontact Sensor for human Motion Perception

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ACS APPLIED MATERIALS & INTERFACES 2025年第14期17卷 21491-21500页

作者： Wang, Shanping Wan, Haicheng Lv, Yu Wang, Peng Meng, Chuizhou Shandong Huayu Univ Technol Sch Elect Engn Dezhou 253000 Peoples R China Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equipm Hebei Key Lab Smart Sensing & Human Robot Interact Engn Res CtrMinist Educ Intelligent Rehabil Devic Tianjin 300401 Peoples R China Univ Jinan Sch Mech Engn Jinan 250022 Peoples R China

Flexible noncontact sensors are of great significance in contemporary applications. Nevertheless, conventional noncontact sensors that rely on metal electrodes have limited flexibility, and their multilayer architectures are likely to experience interfacial delamination during extended use. To tackle these problems, we introduce an all-gel-based flexible triboelectric noncontact sensor, which consists of two parts, i.e., the gelatin/poly(vinyl alcohol) (PVA)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/graphene (G) electrode hydrogel and PVA/cellulose/carbon nanotubes (CNT) triboelectric aerogel. The hydrogel electrode not only features outstanding biocompatibility but also exhibits high conductivity. The triboelectric aerogel demonstrates excellent mechanical properties, such as good elasticity and durability. This sensor can stably output a noncontact current of 1.18 mu A, a charge of 18.4 nC/cm2, and a voltage of 3.7 V at a stable state. It can accurately and reliably detect a wide range of human motions, such as elbow bending, knee movement, and running, providing a reliable and flexible approach for human motion perception and facilitating the progress of relevant fields.

关键词： gel-based triboelectric noncontact sensor human motion perception hydrogel and aerogel triboelectric gel

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In2O3-ZnO/Laser-Induced Graphene Nanocomposites for a Highly Sensitive, Room-Temperature, Flexible Methane Gas Sensor

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ACS APPLIED NANO MATERIALS 2025年第15期8卷 7510-7519页

作者： Yang, Li Fu, Wenyuan Mao, Longbiao Xu, Luxiang Yao, Chengpeng Zhang, Hui Cheng, Huanyu Hebei Univ Technol Sch Hlth Sci & Biomed Engn State Key Lab Reliabil & Intelligence Elect Equipm Tianjin 300130 Peoples R China Hebei Univ Technol Sch Mech Engn Hebei Key Lab Smart Sensing & Human Robot Interact Tianjin 300130 Peoples R China Hebei Univ Technol Sch Elect Engn State Key Lab Reliabil & Intelligence Elect Equipm Tianjin 300130 Peoples R China Penn State Univ Dept Engn Sci & Mech University Pk PA 16802 USA

Real-time monitoring of methane can alert for explosion or health issues, but it is still difficult to detect methane with high sensitivity and low detection limit at room temperature. This work reports a highly sensitive room-temperature methane gas sensor based on heterojunction nanocomposites between n-type indium-zinc oxide (In2O3-ZnO) and p-type porous laser-induced graphene (LIG) prepared by laser direct writing and facile spray coating. The resulting In2O3-ZnO/LIG-based methane gas sensor exhibits a large response of -27.48% to 500 ppm methane room temperature, a fast response/recovery time of 48/169 s, and an experimentally demonstrated ultralow detection limit of 3 ppm. After confirming the stable response over 9 days and against bending with a radius of curvature down to 10 mm, the In2O3-ZnO/LIG gas sensors are further combined with a wireless powering and transmitting module into an integrated methane gas sensing device to wirelessly detect methane in real time for early warning and safe evacuation in mining and fertilizer plants.

关键词： laser-induced graphene (LIG) nanocomposites In2O3-ZnO heterojunction room-temperaturemethane detection wireless wearable gas sensors mine and industrial methane monitoring

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