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41.
In this work the problem of designing a state estimator for completely or partially observable continuous nonlinear plants with discrete measurements is addressed. The combination of a geometric approach with a stability analysis yields an estimator design methodology with a nonlinear detectability condition susceptible of testing, a systematic estimator construction, a robust convergence criterion coupled with a simple tuning scheme, as well as a rationale to explain the interplay between sampling time, estimator gains, and estimator functioning. Comparing with the continuous measurement case where the convergence is attained by tuning the gain above a low limit, in the discrete measurement case the loss of information due to the measurement sampling increases the size of the lower gain limit, and imposes sampling time and high gain limits. The proposed methodology is applied to address the estimation problem of a class of solution homopolymerization reactors, and is tested with a methyl-methacrylate polymerization run taken from a previous extended Kalman filter implementation study with experimental data. 相似文献
42.
基于四端参数分析的隔振器传递阻抗测量方法 总被引:1,自引:0,他引:1
基于四端参数网络分析方法,推导了隔振器传递阻抗的计算公式,利用公式中易于测量的固定状态和自由状态的输入阻抗,得到隔振器的传递阻抗数据.根据该方法原理,测量了两种隔振器的实际传递阻抗,由测量结果可知,该方法具有简单、方便、理论依据明确的优点. 相似文献
43.
R. Szukiewicz 《Vacuum》2004,74(1):55-68
The thermal stability of Ta(1 1 1) face covered with Pd layers of different thickness was examined by the complementary scanning tunnelling microscope (STM), low-energy electron diffraction (LEED), Auger electron spectroscopy and Δφ techniques. It has been found that for thin layers of θ<3 monolayer (ML) heated to 450 K, uplifts appear on the surface that may be treated as an agglomerated form of Pd adsorbate. For layers thicker than θ>3 ML, facets of the {1 1 0} type were observed upon heating to 700 K. Regardless of the conditions of investigation the faceting of the {2 1 1} type did not appear. During the adsorbate desorption the STM images revealed an ordered arrangement of surface atoms in the form of micropyramids composed of 10 atoms each and equally oriented towards the substrate. The appearance of the pyramids on the surface did not affect the observed LEED pattern. 相似文献
44.
D. Claire F. Hild S. Roux 《International journal for numerical methods in engineering》2004,61(2):189-208
It is proposed to determine damage parameters in two dimensions (surface of a material) or three dimensions (in the bulk of a solid) by using full‐field displacement measurements. A finite‐element approach is developed to evaluate piece‐wise constant elastic parameters modeled by an isotropic damage variable. Two sets of examples are discussed. The first series deals with mechanical fields obtained by finite element simulations to assess the performance of the approach. The second series is concerned with displacement measurements performed during a biaxial test on a composite material. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
45.
Many practical problems of quality control involve the use of ordinal scales. Questionnaires planned to collect judgments on qualitative or linguistic scales, whose levels are terms such as “good,” “bad,” “medium,” etc., are extensively used both in evaluating service quality and in visual controls for manufacturing industry. In an ordinal environment, the concept of distance between two generic levels of the same scale is not defined. Therefore, a population (universe) of judgments cannot be described using “traditional” statistical distributions since they are based on the notion of distance. The concept of “distribution shape” cannot be defined as well. In this article, we introduce a new statistical entity, the so-called ordinal distribution, to describe a population of judgments expressed on an ordinal scale. We also discuss which of the traditional location and dispersion measures can be used in this context and we briefly analyze some of their properties. A new dispersion measure, the ordinal range, as an extension of the cardinal range to ordinal scales, is then proposed. A practical application in the field of quality is developed throughout the article. 相似文献
46.
Gaurang Pant Prakaipetch Punchaipetch M. J. Kim Robert M. Wallace Bruce E. Gnade 《Thin solid films》2004,460(1-2):242-246
Physical and electrical properties of hafnium silicon oxynitride (HfSixOyNz) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSixOyNz are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10−5 A/cm2 at Vfb+1 V. The films have a breakdown field strength >10 MV/cm. 相似文献
47.
Amorphous Si (a-Si) thin film anodes were prepared by pulsed laser deposition (PLD) at room temperature. Structures and properties of the thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and electrochemical measurements. Galvanostatic charge/discharge tests of half cells using lithium counter electrode were conducted at a constant current density of 100 μA/cm2 in different voltage windows. Cyclic voltammetry (CV) was obtained between 0 and 1.5 V at various scan rates from 0.1 to 2 mV/s. The apparent diffusion coefficient (DLi) calculated from the CV measurements was about ∼10−13 cm2/s. The Si thin film anode was also successfully coupled with LiCoO2 thin film cathode. The a-Si/LiCoO2 full cell showed stable cycle performance between 1 and 4 V. 相似文献
48.
Jiaxiong XuRuohe Yao 《Thin solid films》2011,520(1):515-518
Boron-doped or phosphorus-doped β-FeSi2 thin films have been prepared on silicon substrate by magnetron sputtering. Effects of Si/Fe ratio on the boron and phosphorus doping efficiencies have been studied from the resistivities of doped β-FeSi2 thin films and current-voltage characteristics of doped β-FeSi2/Si heterojunctions. The experimental results reveal that the carrier concentration and doping efficiency of boron or phosphorus dopants at the Fe-rich side are higher than that at the Si-rich side. The effect of Si/Fe ratio can be deduced from the comparison of the formation energies under two extreme conditions. At the Fe-rich limit condition, the formation energy of boron or phosphorous doping is lower than that at the Si-rich condition. Therefore, the activation of impurities is more effective at the Fe-rich side. These results demonstrate that the boron-doped and phosphorous-doped β-FeSi2 thin films should be kept at the Fe-rich side to avoid the unexpected doping sites and low doping efficiency. 相似文献
49.
Oriented La0.75Ca0.25MnO3 (LCMO) films have been deposited by pulsed laser deposition (PLD) method on (100) LaAlO3 substrates. Ion-beam technique is used to introduce a very low concentration of57Fe in LCMO film. The deposited films were subjected to 100 keV57Fe+ implantation with different fluences at room temperature. The main motivation of this work was to study the influence of implantation on the transport mechanism in materials exhibiting colossal magnetoresistance (CMR) property. It is observed that Fe implantation drastically affects the structural and magneto-transport properties. The samples were characterized using the X-ray diffraction (XRD) technique, conversion electron Mössbauer spectroscopy (CEMS) and resistance temperature (R-T) measurements. 相似文献
50.
Ni0.11ZnxCo0.03Fe2.86-xO4 spinel ferrite films with x = 0.00, 0.23, 0.34, 0.43 and 0.51 were prepared on Ag-coated glass substrates from nitrate and dimethylamine borane solution at 80 °C. The Ni0.11ZnxCo0.03Fe2.86-xO4 ferrite films are singe-phased spinel ferrite. With the Zn content x increasing from 0 to 0.51, the lattice constant of the ferrite films increases from 0.8383 to 0.8425 nm. The Ni0.11Zn0.51Co0.03Fe2.35O4 film is about 500 nm thick and composed of uniform equiaxed granules of about 40–50 nm. The Raman spectrum analysis indicates that the Zn2+ ions occupy the A sites. Saturation magnetization increases with x increasing from 0 to 0.35, reaches a maximum value of 460 kA/m at x = 0.35, and then decreases with further increase of x. Coercivity decreases monotonically from 12.3 to 1.7 kA/m with x increasing from 0 to 0.51. The change in magnetic properties may be explained by the decrease of A–B interactions and the anisotropy constant due to the incorporation of non-magnetic Zn2+ ions. 相似文献