共查询到14条相似文献,搜索用时 546 毫秒
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考虑同时存在状态不确定性和控制不确定性的时滞系统的滑模控制问题,其中控制不确定性是不匹配的。利用Lyapunov方法和线性矩阵不等式技术,给出了闭环系统渐近稳定的充分条件。利用该线性矩阵不等式的解可以得到所设计的滑模控制律和滑模面。从理论上证明了该滑模控制律能保证状态轨迹被驱动到指定的切换面上。仿真结果验证了该算法的有效性。 相似文献
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在时域中,对线性时滞参数扰动系统提出了一种新的鲁棒状态反馈控制器设计方法,利用矩阵的测度和范数的性质,得到了在参数结构扰动和非结构扰动下的线性时滞系统a鲁棒稳定性的充分条件,给出了满足鲁棒性要求的鲁棒状态反馈控制器的设计方法,并举例表明该设计方法简单易行。 相似文献
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考虑存在状态和输入时滞情况下It随机系统的滑模控制问题。通过设计一个新的切换函数,不仅可以有效解决存在状态和输入时滞情况下随机系统的滑模控制器的设计问题,而且可以保证系统状态轨迹从初始时刻就发生滑模运动,从而使得系统在整个状态空间上都具有不变性。利用线性矩阵不等式给出了保证滑模动态依概率渐近稳定的充分条件,最后给出了数值仿真结果。 相似文献
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针对允许执行器发生故障的不确定系统,分别研究了被动可靠以及自适应可靠滑模控制器的设计,通过线性矩阵不等式技术和李雅普诺夫稳定性理论证明了滑模运动的稳定性、指定滑模面的可达性,数值仿真结果验证了该方法的有效性。 相似文献
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针对一类具有参数不确定的T akag i-Sugeno(T-S)模糊系统,基于模糊区域的概念研究了其鲁棒控制问题。通过将不确定T-S模糊模型转换为不确定T-S模糊区域模型,并利用Lya-punov稳定性理论,导出了线性矩阵不等式(LM I)形式的鲁棒控制器设计方法。相对于传统设计方法,降低了采用线性矩阵不等式方法求解的难度,并具有良好的鲁棒性能。仿真结果验证了该方法的有效性。 相似文献
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把不确定系统的鲁棒极点配置与LQR问题相结合,首先通过矩阵变换,将不确定系统的区域极点问题转换成鲁棒镇定问题,然后通过优化二次型性能指标,得到状态反馈控制器,并提出了相应的算法。仿真结果表明了此方法的有效性。 相似文献
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目的 对比经阴道三维超声多平面模式与二维超声在计数窦卵泡(AFC)方面的可靠度及计数时间。方法 以2012年10月-2015年4月在该院妇产科就诊或检查的妇女为受试对象,由两名经验丰富的工作人员独立以二维和三维模式进行AFC,对比其计数差异,计算相关系数及一致性限度,对比计数时间。结果 ①对3个不同年龄段受试者而言,两名观察者的计数结果差异无统计学意义(P >0.05),同一观测者以不同方法的计数结果也未见显著差异(P >0.05);②不同观察者以同一方法行AFC所用时间差异无统计学意义(P > 0.05),但同一观察者以三维超声模式行AFC所需时间明显高于二维超声(P <0.01);③两名观察者以三维超声多平面模式行AFC的差值范围与一致性限度范围更小,差值的均值更低,相关系数更高;④三维超声多平面模式对卵巢低反应性的诊断的准确度与敏感均更高。结论 三维超声多平面模式在行AFC时具有比二维超声更高的可靠度、一致性及准确度,虽其计数时间明显增加,但可大大缩短患者暴露的时间。
相似文献14.
《Journal of Pharmaceutical Analysis》2022,12(1):136-144
Comprehensive characterization of metabolites and metabolic profiles in plasma has considerable significance in determining the efficacy and safety of traditional Chinese medicine (TCM) in vivo. However, this process is usually hindered by the insufficient characteristic fragments of metabolites, ubiquitous matrix interference, and complicated screening and identification procedures for metabolites. In this study, an effective strategy was established to systematically characterize the metabolites, deduce the metabolic pathways, and describe the metabolic profiles of bufadienolides isolated from Venenum Bufonis in vivo. The strategy was divided into five steps. First, the blank and test plasma samples were injected into an ultra-high performance liquid chromatography/linear trap quadrupole-orbitrap-mass spectrometry (MS) system in the full scan mode continuously five times to screen for valid matrix compounds and metabolites. Second, an extension-mass defect filter model was established to obtain the targeted precursor ions of the list of bufadienolide metabolites, which reduced approximately 39% of the interfering ions. Third, an acquisition model was developed and used to trigger more tandem MS (MS/MS) fragments of precursor ions based on the targeted ion list. The acquisition mode enhanced the acquisition capability by approximately four times than that of the regular data-dependent acquisition mode. Fourth, the acquired data were imported into Compound Discoverer software for identification of metabolites with metabolic network prediction. The main in vivo metabolic pathways of bufadienolides were elucidated. A total of 147 metabolites were characterized, and the main biotransformation reactions of bufadienolides were hydroxylation, dihydroxylation, and isomerization. Finally, the main prototype bufadienolides in plasma at different time points were determined using LC-MS/MS, and the metabolic profiles were clearly identified. This strategy could be widely used to elucidate the metabolic profiles of TCM preparations or Chinese patent medicines in vivo and provide critical data for rational drug use. 相似文献