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Xin Wang,Xin Zuo,Jianwei Liu,Huaqing Liang,Qi Pan 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
This paper is concerned with the robust discrete-time control for uncertain time-delay systems with nonlinearities and external noises. The parameter uncertainties enter into all the system matrices. The time-varying delay is unknown with given lower and upper bounds. The stochastic nonlinearities are described by satisfying a class of α Hölder condition. The problem addressed is the analysis and design of a stable controller such that, for all the parameter uncertainties, time-delay, stochastic nonlinearities and external noises, the resulting closed-loop system is exponentially stabile. The controller gain can be got by linear matrix inequalities (LMIs). Numerical examples are given to illustrate the effectiveness and verify the proposed theoretical results.
Chongyu Jia,Renjie Zhang,Jiaqi Wang,Bo Zhang,Huaqing Zhang,Liang Kang,Luping Zhou,Cailiang Shen 대한척추신경외과학회 2023 Neurospine Vol.20 No.4
Objective: This study assessed biomechanical properties of pedicle screws enhanced or revised with 3 materials. We aimed to compare the efficacy of these materials in pedicle augmentation and revision. Methods: One hundred twenty human cadaveric vertebrae were utilized for in vitro testing. Vertebrae bone density was evaluated. Allograft bone particles (ABP), calcium phosphate cement (CPC), and demineralized bone matrix (DBM) were used to augment or revise pedicle screw. Post the implantation of pedicle screws, parameters such as insertional torque, pullout strength, cycles to failure and failure load were measured using specialized instruments. Results: ABP, CPC, and DBM significantly enhanced biomechanical properties of the screws. CPC augmentation showed superior properties compared to ABP or DBM. ABP-augmented screws had higher cycles to failure and failure loads than DBM-augmented screws, with no difference in pullout strength. CPC-revised screws exhibited similar strength to the original screws, while ABP-revised screws showed comparable cycles to failure and failure loads but lower pullout strength. DBM-revised screws did not match the original screws’ strength. Conclusion: ABP, CPC, and DBM effectively improve pedicle screw stability for pedicle augmentation. CPC demonstrated the highest efficacy, followed by ABP, while DBM was less effective. For pedicle revision, CPC is recommended as the primary choice, with ABP as an alternative. However, using DBM for pedicle revision is not recommended.