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Zhang X.,Shandong Jianzhu University | Baron L.,Ecole Polytechnique de Montreal | Liu Q.,Shandong University of Finance and Economics | Boukas E.-K.,Ecole Polytechnique de Montreal
IEEE Transactions on Automatic Control | Year: 2011

In this technical note, constructive control techniques have been proposed for controlling feedforward nonlinear time-delay systems. The nonlinear terms admit an incremental rate depending on the input or delayed input. Based on the Lyapunov-Razumikhin theorem and Lyapunov-Krasovskii theorem, the delay-independent feedback controllers are explicitly constructed such that the closed-loop systems are globally asymptotically stable. An example is given to demonstrate the effectiveness of the proposed design procedure. © 2006 IEEE.


Yuan X.-D.,Shandong Jianzhu University | Yang X.-J.,Shandong Supervision and Inspection Institute for Product Quality
Wear | Year: 2010

The friction and wear properties of polytetrafluoroethylene (PTFE) coatings were studied in detail on a ball-on-disk wear tester under vacuum conditions. Experimental results showed that the friction coefficients of the PTFE coatings first increased with the increase of sliding velocity and then decreased with the increase of sliding velocity when the sliding velocity was higher than 1.2. m/s. The wear of the PTFE coating first decreased with the increase of sliding speed and then increased as the sliding speed increased. The friction coefficient decreased with the increase of load. The wear of PTFE coating first decreased with the increase of load and then increased with the increase of load when the load was higher than 6. N. The environmental pressure has insignificant effect on the friction coefficient of PTFE coating, and the friction coefficient of PTFE coating under air condition is slightly higher than that under vacuum condition. The wear first decreased with the increase of environmental pressure and then increased rapidly with the increase of environmental pressure when the pressure was higher than10. Pa. Scanning electron microscope (SEM) was utilized to investigate the worn surfaces, the self-lubricating films and debris. © 2010 Elsevier B.V.


Li J.,Shandong Jianzhu University | Yu D.-H.,Chinese Academy of Sciences
CMES - Computer Modeling in Engineering and Sciences | Year: 2011

The composite rectangle (midpoint) rule for the computation of multidimensional singular integrals is discussed, and the superconvergence results is obtained. When the local coordinate is coincided with certain priori known coordinates, we get the convergence rate one order higher than the global one. At last, numerical examples are presented to illustrate our theoretical analysis which agree with it very well. © 2011 Tech Science Press.


Zhang X.,Shandong Jianzhu University | Liu Q.,Shandong University of Finance and Economics | Baron L.,Ecole Polytechnique de Montreal | Boukas E.-K.,Ecole Polytechnique de Montreal
Automatica | Year: 2011

This paper investigates the problem of global strong stabilization by state feedback, for a family of high order feedforward nonlinear time-delay systems. The uncertain nonlinearities are assumed to satisfy a polynomial growth assumption with an input or delayed input dependent rate. With the help of the appropriate LyapunovKrasovskii functionals, and a rescaling transformation with a gain to be tuned online by a dynamic equation, we propose a dynamic low gain state feedback control scheme. A simulation example is given to demonstrate the effectiveness of the proposed design procedure. © 2011 Elsevier Ltd. All rights reserved.


Observation data sets from three different periods and 23 International GNSS Service (IGS) stations spread over the world were processed in static mode using four online free precise point positioning (PPP) services: Automatic Precise Positioning Service (APPS), GPS Analysis and Positioning Software, Canadian Spatial Reference System precise point positioning service, and Magic-PPP. The estimated positions of the 23 IGS stations were compared with the published values. The estimated zenith tropospheric delays (ZTDs) at these stations were compared with the corresponding IGS troposphere products published on the IGS Web site. Furthermore, in order to analyze PPP precision for short observation periods, GPS observation data sets with a sampling rate of 1 s collected by one CORS station were also processed by the four online PPP services. Calculation shows that the precision of daily solutions for north and east (N/E) components estimated by the four online PPP services can reach millimeter level, the precision of ellipsoid elevation (H) can reach 1–2 cm, and precision of ZTDs estimation results is approximately 1–2 cm. Compared with the corresponding values published on the IGS Web site, the precision of ZTDs estimated by APPS is higher than those estimated by the other three PPP online services; the differences between ZTDs by APPS and IGS values are mostly within ±1 cm. For PPP with short observation periods, the precision of N/E components within 2, 1, and 0.5 h observation periods can reach about 2–3, 2–7, and 3–8 cm, respectively, while the precision of H components is about 3–5, 5–12, and 10–18 cm, respectively. © 2014, Springer-Verlag Berlin Heidelberg.

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