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Jingjing Xu,Zhifeng Liu,Yongsheng Zhao,Yanhu Pei,Qiang Cheng 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.5
In the bolt looseness detection task of the locomotive system, the robot could be used to highly improve the working efficiency and reliability, but faces the complex static obstacles while planning the path for the robotic motion. In this paper, a path optimization technique is proposed to obtain an optimal path with obstacle avoidance for a redundant robot in the static complicated environment. There are three main contributions in this technique. The first is the solving of the inverse kinematics problem for a redundant robot based on the screw theory and the geometric description, which is general to all robots with rotational joints. The second is the modeling of the spatial constraint, where the pseudo distance is defined based on the plane description of the obstacles and calculated using the spatial analytic geometry knowledge. The third is the presentation of the whole path-planning framework based on the above two contributions, which could largely improve the generality of the presented technique. In this framework, the minimum-time path could be obtained while guaranteeing both the motion stability and obstacle avoidance. Moreover, a real setting that includes an obstacle environment and an 8-DOF robot, is taken as an example to better present the technique. Finally, the simulation experiment was performed in Isight software to verify the effectiveness of the path optimization technique.
Jingjing Xu,한우재 대한청각학회 2014 Journal of Audiology & Otology Vol.18 No.3
This systematic review evaluated the impact of using digital pinna-cue preserving technologies (PPT) on front/back sound localization for adult hearing aid users. Two peer-reviewed studies and two non-peer-reviewed studies were included. Lab-based and self-report outcomes were both assessed. The overall findings suggested that PPT was superior to omni-directional and full directional settings in a relatively quiet, well-controlled laboratory environment but not in the real world. However, observed individual differences in self-report measures suggested that PPT was potentially beneficial to certain hearing aid users. PPT candidacy was discussed and the importance of a pre-fitting interview/consultation was emphasized to assist clinicians in making a solid evidence-based and cost-effectiveness decision when prescribing hearing aids to adults with hearing impairment.
Nonlinear Kalman filter bias correction for wind ramp event forecasts at wind turbine height
Jingjing Xu,Zi-Niu Xiao,Zhao-Hui Lin 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.4
One of the growing concerns of the wind energy production is wind ramp events. To improve the wind ramp event forecasts, the nonlinear Kalman filter bias correction method was applied to 24-h wind speed forecasts issued from the WRF model at 70-m height in Zhangbei wind farm, Hebei Province, China for a two-year period. The Kalman filter shows the remarkable ability of improving forecast skill for real-time wind speed forecasts by decreasing RMSE by 32% from 3.26 m s-1 to 2.21 m s-1, reducing BIAS almost to zero, and improving correlation from 0.58 to 0.82. The bias correction improves the forecast skill especially in wind speed intervals sensitive to wind power prediction. The fact shows that the Kalman filter is especially suitable for wind power prediction. Moreover, the bias correction method performs well under abrupt weather transition. As to the overall performance for improving the forecast skill of ramp events, the Kalman filter shows noticeable improvements based on POD and TSS. The bias correction increases the POD score of up-ramps from 0.27 to 0.39 and from 0.26 to 0.38 for down-ramps. After bias correction, the TSS score is significantly promoted from 0.12 to 0.26 for up-ramps and from 0.13 to 0.25 for down-ramps.
Refolding Behavior of Urea-Induced Denaturation Collagen
Xu Wei,Yanqiu Zhao,Jingjing Zheng,Qin Cao,Sheng Li,Lang He,Benmei Wei,Juntao Zhang,Chengzhi Xu,Haibo Wang 한국고분자학회 2021 Macromolecular Research Vol.29 No.6
Exploration of the denaturation and refolding of natural collagen is important for the application of collagen and its denatured products. In this study, using urea as a denaturant, we prepared a denatured natural collagen product and analyzed its structural changes. The denaturation treatment severely destroyed the triple helix conformation of collagen, but had no significant effect on the primary structure of its α chains or the covalent cross-linking between α chains. Next, we observed the refolding behavior of the denatured collagen by removing urea through dialysis. We found that the denatured collagen products from different sources (grass carp skin, bovine tendon) all showed a reconstruction of the triple helix conformation up to 60-75% of the value of natural collagen during the refolding process. The telopeptide did not significantly promote triple helix reconstruction. In conclusion, the reconstruction of the α chains did not perfectly occur in a “head-to-head, tail-to-tail” manner in refolded collagen, as each α chain was participating in the reconstruction of multiple triple helix domains. The refolded collagen still had weak self-assembly ability and formed a unique network-like structure containing small interlaced and closely combined fibers, which shows favorable cell compatibility and potential applications.
Jingjing Gao,Xu Yang,Jian Huang,Kaixiang Peng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.1
Stimulated by the enhancing requirements for system safety as well as process reliability in industrial processes, this paper investigates a subspace aided fault-tolerant control scheme for distributed homogeneous systems with symmetric interconnection pattern. To this end, a decomposition approach is first addressed to show how to convert and decompose the original distributed homogeneous system into a set of independent subsystems. Then, for the independent subsystems, offline subspace predictive controllers and recursive fault-tolerant subspace predictive controllers are designed respectively in a decentralized way. Finally, the controllers designed for the independent subsystems are converted back to the original distributed homogeneous system to achieve its faulttolerant control goal. The effectiveness of the proposed scheme is demonstrated by a case study on a multi-area interconnected power system.
Ultrafast epitaxial growth of metre-sized single-crystal graphene on industrial Cu foil
Xu, Xiaozhi,Zhang, Zhihong,Dong, Jichen,Yi, Ding,Niu, Jingjing,Wu, Muhong,Lin, Li,Yin, Rongkang,Li, Mingqiang,Zhou, Jingyuan,Wang, Shaoxin,Sun, Junliang,Duan, Xiaojie,Gao, Peng,Jiang, Ying,Wu, Xiaoson Elsevier 2017 Science bulletin Vol.62 No.15
ABEP Performance of ISDF Relaying M2M Cooperative Networks
Xu, Lingwei,Wang, Jingjing,Wang, Han,Gulliver, T. Aaron Korean Society for Internet Information 2016 KSII Transactions on Internet and Information Syst Vol.10 No.12
In this paper, the average bit error probability (ABEP) performance of the incremental-selective decode-and-forward (ISDF) relaying mobile-to-mobile (M2M) cooperative networks over N-Nakagami fading channels is investigated. The exact ABEP expressions are derived, and the power allocation problem is formulated.The derived ABEP expressions are verified by Monte Carlo simulations. The simulation results showed that the propagation parameters, such as the fading coefficient, and the power-allocation parameter, have a significant influence on the ABEP performance.
End-to-End Performance Analysis of AF Relaying M2M Cooperative System
Lingwei Xu,Hao Zhang,Jingjing Wang,Wei Shi,T. Aaron Gulliver 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.9
In this paper, the end-to-end performance of the mobile-relay-based mobile-to-mobile (M2M) system with amplify-and-forward (AF) relaying over N-Nakagami fading channels is investigated. The exact closed-form expressions for the lower bound on average symbol error probability (ASEP) and upper bound on channel capacity are derived. Then the ASEP and channel capacity performance under different conditions is evaluated to confirm the accuracy of the analysis. Results are presented which show that the fading coefficient, the number of cascaded components, the relative geometrical gain, and the power-allocation parameter have an important influence on the ASEP and channel capacity performance.