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RISS 인기검색어
- 검색키워드
- 저자 : Junjie Niu (검색결과 5 건)
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Niu, Gang,Jiang, Junjie,Youn, Byeng D.,Pecht, Michael Elsevier 2018 ISA transactions Vol.72 No.-
<P><B>Abstract</B></P> <P>Autonomous vehicles are playing an increasingly importance in support of a wide variety of critical events. This paper presents a novel autonomous health management scheme on rail vehicles driven by permanent magnet synchronous motors (PMSMs). Firstly, the PMSMs are modeled based on first principle to deduce the initial profile of pneumatic braking (p-braking) force, then which is utilized for real-time demagnetization monitoring and degradation prognosis through similarity-based theory and generate prognosis-enhanced p-braking force strategy for final optimal control. A case study is conducted to demonstrate the feasibility and benefit of using the real-time prognostics and health management (PHM) information in vehicle ‘drive-brake’ control automatically. The results show that accurate demagnetization monitoring, degradation prognosis, and real-time capability for control optimization can be obtained, which can effectively relieve brake shoe wear.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel autonomous health management scheme for PMSM Rail Vehicles. </LI> <LI> Accurate demagnetization monitoring and degradation prognosis. </LI> <LI> Real-time prognosis-enhanced optimal control capability. </LI> <LI> Integrated control characteristic for ‘drive-brake’ systems. </LI> <LI> Advanced prognosis control enabled maintenance optimization. </LI> </UL> </P>
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Yuansheng Ning,Hongbo Wang,Junjie Tian,Hao Yan,Yu Tian,Congliang Yang,Jian Wei,Jianye Niu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
Upper extremity exoskeleton rehabilitation robots can be used for the training of patients with upper extremity motor dysfunction. In most cases, the design of such robots focuses on the configuration and the human-machine compatibility. For patients, the use of an exoskeleton rehabilitation robot mainly aims to improve their movement ability, which depends on the range of movement of the upper extremity joints. This paper proposes an eight-degreeof-freedom (DOF) upper extremity exoskeleton rehabilitation robot to improve the movement range of the patient’s upper extremity joints. The structural parameters of the shoulder joint are optimized and analyzed by the kinematic equations of the mechanism and the cyclic iteration algorithm such that the movement range of the patient joint can be maximized. The movement space of the robot is then simulated. Finally, the movement range of the rehabilitation robot joints and the movement space of the rehabilitation robot were measured. Experimental results show that the upper extremity exoskeleton rehabilitation robot can meet the patient’s shoulder, elbow, and wrist movement range, and the overlap with the human upper extremity movement space is 97.1 % and 95.7 % in the coronal and sagittal planes, respectively.
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Numerical analysis of stress wave of projectile impact composite laminate
Zhangxin Guo,Weijing Niu,Junjie Cui,Gin Boay Chai,Yongcun Li,Xiaodong Wu 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.2
The three-dimensional Hashin criterion and user subroutine VUMAT were used to simulate the damage in the composite layer, and the secondary stress criterion was used to simulate the interlayer failure of the cohesive element of the bonding layer and the propagation characteristics under the layer. The results showed that when the shear stress wave (shear wave) propagates on the surface of the laminate, the stress wave attenuation along the fiber strength direction is small, and thus producing a large stress profile. When the compressive stress wave (longitudinal wave) is transmitted between the layers, it is reflected immediately instead of being transmitted immediately. This phenomenon occurs only when the energy has accumulated to a certain degree between the layers. The transmission of longitudinal waves is related to the thickness and the layer orientation. Along the symmetry across the thickness direction, the greater is the stress amplitude along the layer direction. Based on the detailed investigation on the impact on various laminated composites carried out in this paper, the propagation characteristics of stress waves, the damage and the destruction of laminates can be explained from the perspective of stress waves and a reasonable layering sequence of the composite can be designed against damage and failure from low velocity impact.
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Jun Zou,Hao Yu,Dawei Song,Junjie Niu,Hui-Lin Yang 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.2
Coronavirus disease 2019 (COVID-19) outbreak started in December 2019 that caused difficulties for clinical work. Practical work experience in our spinal outpatient and emergency department during the COVID-19 pandemic is summarized in this article, with combined evidence-based medical evidence to explore a standardized process of diagnosis and treatment for spinal diseases. Outpatient reservation, continuous screening, triage, and isolation, first consultation accountability system, pandemic reporting system, and online revisit were strictly followed. We hope that our experience in prevention and control of COVID-19 can help spine surgeons globally in stopping the spread of COVID-19. Spine surgeons should collaborate with infection control specialists to avoid cross-infection in hospitals and optimize treatment.
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Improved inverse kinematics and dynamics model research of general parallel mechanisms
Xingchao Zhang,Hongbo Wang,Yu Rong,Jianye Niu,Junjie Tian,Shanshan Li,Yuansheng Ning 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2
Since the classical kinematics model of parallel manipulators cannot accurately reflect the angular velocity and angular acceleration of the limbs, an improved kinematics model is proposed and an inverse dynamic model of the general parallel manipulator is derived based on the improved kinematics model. This paper proves that the shortcoming of the classical kinematics model is that a single model cannot accurately describe the movement of several types of branches in a parallel manipulator. Combined with the principle of angular velocity superposition and vector chain method, the improved kinematic models of the general parallel manipulator’s several typical limbs are derived. Then, an explicit inverse dynamic model of a general parallel robot is established based on the principle of virtual work. Finally, to describe the effectiveness of the improved model, we analyzed a new type of UP+SPR+SPU parallel manipulator. The improved models had higher accuracy than the classical models through the comparison.
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