The displacement feedback with time delay considered is introduced in order to enhance the vibration isolation performance of a high-static-low-dynamic stiffness(HSLDS) vibration isolator. Such feedback is detailedly ...The displacement feedback with time delay considered is introduced in order to enhance the vibration isolation performance of a high-static-low-dynamic stiffness(HSLDS) vibration isolator. Such feedback is detailedly analyzed from the viewpoint of equivalent damping. Firstly, the primary resonance of the controlled HSLDS vibration isolator subjected to a harmonic force excitation is obtained based on the multiple scales method and further verified by numerical integration. The stability of the primary resonance is subsequently investigated. Then, the equivalent damping is defined to study the effects of feedback gain and time delay on primary resonance. The condition of jump avoidance is obtained with the purpose of eliminating the adverse effects induced by jumps. Finally, the force transmissibility of the controlled HSLDS vibration isolator is defined to evaluate its isolation performance. It is shown that an appropriate choice of feedback parameters can effectively suppress the force transmissibility in resonant region and reduce the resonance frequency. Furthermore, a wider vibration isolation frequency bandwidth can be achieved compared to the passive HSLDS vibration isolator.展开更多
The problem of designing fuzzy static output feedback controller for T-S discrete-time fuzzy bilinear system （DFBS） is presented. Based on parallel distribution compensation method, some sufficient conditions are de...The problem of designing fuzzy static output feedback controller for T-S discrete-time fuzzy bilinear system （DFBS） is presented. Based on parallel distribution compensation method, some sufficient conditions are derived to guarantee the stability of the overall fuzzy system. The stabilization conditions are further formulated into linear matrix inequality （LMI） so that the desired controller can be easily obtained by using the Matlab LMI toolbox. In comparison with the existing results, the drawbacks, such as coordinate transformation, same output matrices, have been elim- inated. Finally, a simulation example shows that the approach is effective.展开更多
为探究静磁场辅助冷冻(static magnetic field assisted freezing,SMAF)对牛肉品质的影响,采用不同强度SMAF(0、2、4、6、8、10 mT,-18℃),对比分析冷冻参数对牛背最长肌品质的影响。结果表明:与对照组相比,SMAF-6、8、10处理组相变时...为探究静磁场辅助冷冻(static magnetic field assisted freezing,SMAF)对牛肉品质的影响,采用不同强度SMAF(0、2、4、6、8、10 mT,-18℃),对比分析冷冻参数对牛背最长肌品质的影响。结果表明:与对照组相比,SMAF-6、8、10处理组相变时间分别显著缩短15%、25%和6.7%(P<0.05);SMAF处理有效提高了肌肉的持水性(解冻损失率、蒸煮损失率和离心损失率),降低了样品的ΔE(P<0.05),但对样品的pH值和硫代巴比妥酸反应物值无显著影响(P>0.05);此外,剪切力与肌原纤维小片化指数的结果一致,SMAF处理维持了牛肉的剪切力;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示,SMAF处理可以减少肉品经冷冻-解冻后蛋白质含量的降低。综上,在适当的静磁场强度下辅助冷冻,可节省冻结时间,提高肌肉持水力,减少蛋白质含量的降低,从而改善牛肉品质,其中SMAF-8处理效果最佳。展开更多
基金Project(KYLX15_0256)supported by the Funding of Jiangsu Innovation Program for Graduate Education,ChinaProject(SV2015-KF-01)supported by the Open Project of State Key Laboratory for Strength and Vibration of Mechanical Structures,ChinaProject(XZA15003)supported by the Fundamental Research Funds for the Central Universities,China
文摘The displacement feedback with time delay considered is introduced in order to enhance the vibration isolation performance of a high-static-low-dynamic stiffness(HSLDS) vibration isolator. Such feedback is detailedly analyzed from the viewpoint of equivalent damping. Firstly, the primary resonance of the controlled HSLDS vibration isolator subjected to a harmonic force excitation is obtained based on the multiple scales method and further verified by numerical integration. The stability of the primary resonance is subsequently investigated. Then, the equivalent damping is defined to study the effects of feedback gain and time delay on primary resonance. The condition of jump avoidance is obtained with the purpose of eliminating the adverse effects induced by jumps. Finally, the force transmissibility of the controlled HSLDS vibration isolator is defined to evaluate its isolation performance. It is shown that an appropriate choice of feedback parameters can effectively suppress the force transmissibility in resonant region and reduce the resonance frequency. Furthermore, a wider vibration isolation frequency bandwidth can be achieved compared to the passive HSLDS vibration isolator.
文摘The problem of designing fuzzy static output feedback controller for T-S discrete-time fuzzy bilinear system （DFBS） is presented. Based on parallel distribution compensation method, some sufficient conditions are derived to guarantee the stability of the overall fuzzy system. The stabilization conditions are further formulated into linear matrix inequality （LMI） so that the desired controller can be easily obtained by using the Matlab LMI toolbox. In comparison with the existing results, the drawbacks, such as coordinate transformation, same output matrices, have been elim- inated. Finally, a simulation example shows that the approach is effective.
文摘为探究静磁场辅助冷冻(static magnetic field assisted freezing,SMAF)对牛肉品质的影响,采用不同强度SMAF(0、2、4、6、8、10 mT,-18℃),对比分析冷冻参数对牛背最长肌品质的影响。结果表明:与对照组相比,SMAF-6、8、10处理组相变时间分别显著缩短15%、25%和6.7%(P<0.05);SMAF处理有效提高了肌肉的持水性(解冻损失率、蒸煮损失率和离心损失率),降低了样品的ΔE(P<0.05),但对样品的pH值和硫代巴比妥酸反应物值无显著影响(P>0.05);此外,剪切力与肌原纤维小片化指数的结果一致,SMAF处理维持了牛肉的剪切力;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示,SMAF处理可以减少肉品经冷冻-解冻后蛋白质含量的降低。综上,在适当的静磁场强度下辅助冷冻,可节省冻结时间,提高肌肉持水力,减少蛋白质含量的降低,从而改善牛肉品质,其中SMAF-8处理效果最佳。
