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        Design of a Class of New Nonlinear Disturbance Observers based on Tracking Differentiators for Uncertain Dynamic Systems

        Xiang-Wei Bu,Xiao-Yan Wu,Yong-Xing Chen,Rui-Yang Bai 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.3

        The main contribution of this paper is to present a general design method of new nonlinear disturbance observer (NDO) based on tracking differentiator (TD) for uncertain dynamic system. The stability and convergence of the proposed NDO can be guaranteed by TD. This new NDO can be used to estimate many types of uncertain disturbances, and can overcome the disadvantages of existing NDOs that need the priori information concerning the upper and lower bounds of the disturbance and its ith derivative’s Lipschitz upper bound. It can be also applied in uncertain dynamic system for various purposes such as disturbance estimate and compensation, solving the problem of control input constraint, and reducing even eliminating chattering of control input. Simulation results are presented to show the effectiveness of the developed NDO.

      • 0346 Occupational Exposure to Lead and Cancer in Two Cohort Studies of Men and Women in Shanghai, China

        Liao, Linda M,Friesen, Melissa C,Xiang, Yong-Bing,Cai, Hui,Koh, Dong-Hee,Ji, Bu-Tian,Yang, Gong,Li, Hong-Lan,Locke, Sarah J,Rothman, Nathaniel,Zheng, Wei,Gao, Yu-Tang,Shu, Xiao-Ou,Purdue, Mark P BMJ Publishing Group Ltd 2014 Occupational and environmental medicine Vol.71 No.suppl1

        <P><B>Objectives</B></P><P>Epidemiologic studies of occupational lead exposure have suggested increased risks of cancers of the brain, kidney, lung, meninges, and stomach; however, the totality of the evidence is inconsistent. To clarify whether lead is a carcinogen, we investigated the relationship between occupational lead exposure and risks of these five cancer sites in two prospective cohort studies in Shanghai, China.</P><P><B>Method</B></P><P>Annual job/industry-specific estimates of lead fume and lead dust exposure were derived from a statistical model that combined expert ratings of lead intensity with inspection measurements collected by the Shanghai Centre for Disease Control and Prevention. The job/industry estimates were applied to the lifetime work histories of subjects from the Shanghai Women’s Health Study (73 363 participants) and the Shanghai Men’s Health Study (61 379 participants) to estimate cumulative exposure to lead dust and lead fume. Cohort-specific relative hazard rate ratios (RRs) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression models and then pooled using a random effects meta-analysis model.</P><P><B>Results</B></P><P>We observed a statistically significant increased risk of meningioma among individuals with estimated occupational exposure to lead dust or fumes (RR=2.4, 95% CI:1.1–5.0), and in particular among those with an above-median cumulative exposure to dust or fumes (RR=3.1, 95% CI:1.3–7.4). We observed suggestive associations with lead exposure for cancers of the kidney (RR=1.4, 95% CI:0.9–2.3) and brain (RR=1.8, 95% CI:0.7–4.8), and null findings for cancers of the lung and stomach.</P><P><B>Conclusions</B></P><P>Our findings provide additional evidence that occupational lead exposure increases risk of meningioma.</P>

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