Event-Based H∞ filter design for a class of nonlinear time-varying systems with fading channels and multiplicative noises

In this paper, a general event-triggered framework is developed to deal with the finite-horizon H∞ filtering problem for discrete time-varying systems with fading channels, randomly occurring nonlinearities and multiplicative noises. An event indicator variable is constructed and the corresponding event-triggered scheme is proposed. Such a scheme is based on the relative error with respect to the measurement signal in order to determine whether the measurement output should be transmitted to the filter or not. The fading channels are described by modified stochastic Rice fading models. Some uncorrelated random variables are introduced, respectively, to govern the phenomena of state-multiplicative noises, randomly occurring nonlinearities as well as fading measurements. The purpose of the addressed problem is to design a set of time-varying filter such that the influence from the exogenous disturbances onto the filtering errors is attenuated at the given level quantified by a H∞ norm in the mean-square sense. By utilizing stochastic analysis techniques, sufficient conditions are established to ensure that the dynamic system under consideration satisfies the H∞ filtering performance constraint, and then a recursive linear matrix inequality (RLMI) approach is employed to design the desired filter gains. Simulation results demonstrate the effectiveness of the developed filter design scheme

Finite-horizon estimation of randomly occurring faults for a class of nonlinear time-varying systems

This paper is concerned with the finite-horizon estimation problem of randomly occurring faults for a class of nonlinear systems whose parameters are all time-varying. The faults are assumed to occur in a random way governed by two sets of Bernoulli distributed white sequences. The stochastic nonlinearities entering the system are described by statistical means that can cover several classes of well-studied nonlinearities. The aim of the problem is to estimate the random faults, over a finite horizon, such that the influence from the exogenous disturbances onto the estimation errors is attenuated at the given level quantified by an H∞-norm in the mean square sense. By using the completing squares method and stochastic analysis techniques, necessary and sufficient conditions are established for the existence of the desired finite-horizon H∞ fault estimator whose parameters are then obtained by solving coupled backward recursive Riccati difference equations (RDEs). A simulation example is utilized to illustrate the effectiveness of the proposed fault estimation method

Microstructural characteristics of diecast AlMgSiMn alloy

Solidification and microstructural characteristics of Al-5wt.%Mg-1.5wt.%Si-0.6wt.%Mn- 0.2wt.%Ti alloy have been investigated in high pressure die casting. The average size of dendrites and fragmented dendrites of the primary α-Al phase formed in the shot sleeve is 43μm, and the globular α-Al grains formed inside the die cavity is 7.5μm. Solidification inside the die cavity also forms the lamellar Al-Mg2Si eutectic phase and the Fe-rich intermetallics. The size of the eutectic cells is about 10μm, in which the lamellar α-Al phase is 0.41μm thick. The Fe-rich intermetallic compound exhibits a compact morphology and is less than 2μm. Calculations using the Mullins and Sekerka stability criterion reveal that the solidification of the primary α-Al phase inside the die cavity has completed before the spherical α-Al globules begin to lose their stability, but the α-Al grains formed in the shot sleeve exceed the limit of spherical growth and therefore exhibit a dendritic morphology

全球化下的中国热点城市与区域

自从中国2001年底加入世贸组织以来，跨国公司加大了对华投资的种类和规模。据资料显示，我国外商直接投资2002，2003，2004 年连续三年创历史新高，2004年更首次突破600亿美元，超越美国，位列全球第一。全球化的观念和理念已经深入到中国的角角落落，谁如果忽视了这个力量，谁就会在国际竞争中处于被动地位。对企业而言如此，对地区发展而言更是如此。本文以学术视角总结外商直接投资路径与地区增长模式，并在此框架下点评全球化下的中国热点城市区域，预测中国区域经济下一轮走向。Since China joined the World Trade Organization in 2001, foreign direct investment (FDI) in China had been consecutively broken record in 2002, 2003, and 2004. In 2004, China’s FDI had reached US$60 billion for the first time, surpassing that of the US and becoming World No. 1. The concepts and forces of globalization have substantially influenced China’s development. Based on the studies on the “Investment Path of FDI” and the mode of regional growth, this paper predicts the growth tendency of China’s most dynamic global city-regions in the 11th Five-year Plan period and in the next ten to twenty years.postprin

Finite-horizon reliable control with randomly occurring uncertainties and nonlinearities subject to output quantization

Copyright @ 2014 Elsevier Ltd. All rights reserved.This paper deals with the finite-horizon reliable H∞ output feedback control problem for a class of discrete time-varying systems with randomly occurring uncertainties (ROUs), randomly occurring nonlinearities (RONs) as well as measurement quantizations. Both the deterministic actuator failures and probabilistic sensor failures are considered in order to reflect the reality. The actuator failure is quantified by a deterministic variable varying in a given interval and the sensor failure is governed by an individual random variable taking value on [0,1]. Both the nonlinearities and the uncertainties enter into the system in random ways according to Bernoulli distributed white sequences with known conditional probabilities. The main purpose of the problem addressed is to design a time-varying output feedback controller over a given finite horizon such that, in the simultaneous presence of ROUs, RONs, actuator and sensor failures as well as measurement quantizations, the closed-loop system achieves a prescribed performance level in terms of the H∞-norm. Sufficient conditions are first established for the robust H∞ performance through intensive stochastic analysis, and then a recursive linear matrix inequality approach is employed to design the desired output feedback controller achieving the prescribed H∞ disturbance rejection level. A numerical example is given to demonstrate the effectiveness of the proposed design scheme.This work was supported in part by the National Natural Science Foundation of China under Grants 61329301, 61134009, 61273156, 61333012, 61422301 and 61374127, the Scientific and Technology Research Foundation of Heilongjiang Education Department of China under Grant 12541061, the Engineering and Physical Sciences Research Council (EPSRC) of the U.K., the Royal Society of the U.K., and the Alexander von Humboldt Foundation of Germany

Experimental study of non-Newtonian fluid flow in microchannels

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Non-Newtonian fluid flow in microchannels has significant applications in science and engineering. The effects of temperature and PAM solution concentrations on rheological parameters are analyzed by measuring them with rotating cylinder viscometer. Flow characteristics for deionized water and PAM solutions in fused silica microtubes with diameters ranging from 50 to 320μm, fused silica square microchannels with diameters 75 and 100μm, and stainless steel microtubes with diameters from 120 to 362μm, are studied experimentally. The test results for deionized water in microchannels are in good agreement with theoretical predictions for conventional-size channels. Friction factors of PAM solutions are much higher than theoretical predictions. With the PAM concentration reduced, the deviation is more, which is possibly caused by the significant electroviscous effect on PAM solutions flow in microchannels

湖北省罗田凤凰关混合岩浅色体的类型及其锆石U-Pb年龄

Based on the principle of refolding transecting and overprinting, and eliminating the refolding pseudomorph resulting from the effect of viscous folds, 8-generation leucosomes have been distinguished in the Fenghuangguan migmatites in Luotian, Hubei Province, central China. The results of the major-, trace- and rare earth-element geochemistry indicate that the leucosome for dating the U-Pb age was derived from anatexis. The zircon U-Pb age suggests that there was a migmatization during the Yanshan Period, which may represent an important anatex is at the age, (129. 3 +/- 0. 8) Ma.根据混合岩浅色体的重褶、横切和叠加关系并剔除因粘性褶皱效应引起的重褶皱假象, 在湖北罗田凤凰关识别出8 个世代的浅色体。它们的主量、微量和稀土元素地球化学研究表明, 用于锆石U-Pb 定年的浅色体是深熔成因的。锆石U-Pb 定年结果表明, 在大别杂岩内存在燕山期的混合岩化作用, 其时代为（１２９．３．８）Ｍａ。published_or_final_versio

A novel single-phase voltage sag restorer with diode-clamped multilevel bridge

Author name used in this publication: K. DingAuthor name used in this publication: K. W. E. ChengAuthor name used in this publication: X. D. XueAuthor name used in this publication: C. D. XuVersion of RecordPublishe

Neutron diffraction study of the magnetic order in NdMn2Ge1.6Si0.4

Here we report a detailed investigation of NdMn 2 Ge 1.6 Si 0.4 ; this forms part of our investigation of the magnetic order across the NdMn 2 Ge 2− x Si x (x = 0–2.0) series by magnetometry, x-ray diffraction and neutron diffraction over the temperature range 6–465 K. On decreasing the temperature from 465 K, NdMn 2 Ge 1.6 Si 0.4 exhibits four magnetic transitions: (i) from paramagnetism to intralayer antiferromagnetism AFl at T Intra N ~ 430 K; (ii) AFl to canted ferromagnetism Fmc at T Inter C ~ 330 K; (iii) Fmc to conical magnetic ordering of the Mn sublattice Fmi at T cc ~ 178 K and (iv) Fmi(Mn) to Fmi(Mn)+F(Nd) at T Nd C ~ 72 K. (c) 2011 IOP Publishing LT

Modeling study to compare the flow and heat transfer characteristics of low-power hydrogen, nitrogen and argon arc-heated thrusters

A modelling study is performed to compare the plasma °ow and heat transfer char- acteristics of low-power arc-heated thrusters (arcjets) for three di®erent propellants: hydrogen, nitrogen and argon. The all-speed SIMPLE algorithm is employed to solve the governing equa- tions, which take into account the e®ects of compressibility, Lorentz force and Joule heating, as well as the temperature- and pressure-dependence of the gas properties. The temperature, veloc- ity and Mach number distributions calculated within the thruster nozzle obtained with di®erent propellant gases are compared for the same thruster structure, dimensions, inlet-gas stagnant pressure and arc currents. The temperature distributions in the solid region of the anode-nozzle wall are also given. It is found that the °ow and energy conversion processes in the thruster nozzle show many similar features for all three propellants. For example, the propellant is heated mainly in the near-cathode and constrictor region, with the highest plasma temperature appear- ing near the cathode tip; the °ow transition from the subsonic to supersonic regime occurs within the constrictor region; the highest axial velocity appears inside the nozzle; and most of the input propellant °ows towards the thruster exit through the cooler gas region near the anode-nozzle wall. However, since the properties of hydrogen, nitrogen and argon, especially their molecular weights, speci¯c enthalpies and thermal conductivities, are di®erent, there are appreciable di®er- ences in arcjet performance. For example, compared to the other two propellants, the hydrogen arcjet thruster shows a higher plasma temperature in the arc region, and higher axial velocity but lower temperature at the thruster exit. Correspondingly, the hydrogen arcjet thruster has the highest speci¯c impulse and arc voltage for the same inlet stagnant pressure and arc current. The predictions of the modelling are compared favourably with available experimental results