Parameter Estimation of Switched Hammerstein Systems

This paper deals with the parameter estimation problem of the Single-Input-Single-Output (SISO) switched Hammerstein system. Suppose that the switching law is arbitrary but can be observed online. All subsystems are parameterized and the Recursive Least Squares (RLS) algorithm is applied to estimate their parameters. To overcome the difficulty caused by coupling of data from different subsystems, the concept "intrinsic switch" is introduced. Two cases are considered: i) The input is taken to be a sequence of independent identically distributed (i.i.d.) random variables when identification is the only purpose; ii) A diminishingly excited signal is superimposed on the control when the adaptive control law is given. The strong consistency of the estimates in both cases is established and a simulation example is given to verify the theoretical analysis.Comment: 16 pages, 3 figures; Accepted for publication by Acta Mathematicae Applicatae Sinica (http://link.springer.com/journal/10255

Dynamical symmetries of the Klein-Gordon equation

The dynamical symmetries of the two-dimensional Klein-Gordon equations with equal scalar and vector potentials (ESVP) are studied. The dynamical symmetries are considered in the plane and the sphere respectively. The generators of the SO(3) group corresponding to the Coulomb potential, and the SU(2) group corresponding to the harmonic oscillator potential are derived. Moreover, the generators in the sphere construct the Higgs algebra. With the help of the Casimir operators, the energy levels of the Klein-Gordon systems are yielded naturally.Comment: 4

Fiscal decentralization, revenue and expenditure assignments, and growth in China

Theory suggests that a close match between revenue and expenditure assignments at sub-national levels benefits allocative efficiency, and hence economic growth. That is, a convergence of revenue and expenditure assignments at sub-national levels of government should, according to the theory, be positively associated with a higher growth rate. In the case of China, this paper shows, divergence, rather than convergence, in revenue and expenditures at the sub-national level of government is associated with higher rates of growth. A panel dataset for 30 provinces in China is used to examine the relationship between fiscal decentralization and economic growth over two phases of fiscal decentralization in China: (1) 1979¨C1993 under the fiscal contract system, and (2) 1994¨C1999 under the tax assignment system. The seeming contradiction between the theory and evidence in the China case is reconciled by taking into account the institutional arrangements that prevailed during the two phases of fiscal decentralization, in particular the inconsistency between the assumptions of the theory of fiscal decentralization and the institutional reality of China.Fiscal decentralization, Economic growth, Revenue, Expenditure

Characterization of Fine Powders and Development of Processes for Powder Coatings

Traditional powder coating provides poor coating appearance. Fine powder coating can overcome this drawback since the smaller powder particles lead to much smoother finish. Nevertheless, fine powder has been experienced to cause more application problems. This study investigated fine powder coatings from different aspects and it provided solutions to solve these application problems. The investigation on fine powders conducted by this study concluded that the medium particle size and D10 was not suitable for the flowability characterization of fine powder coatings. Instead, an index which represented the particle size distribution could correlate with the flowabilities of the fine powder coatings much better. In addition, several processing methods were developed for the production of fine powder coatings. The experiments disclosed that the revised designs of the cyclone and the grinder could obtain narrower particle size distribution of the powder coatings, which was desired. In addition, other performances of the processes were not sacrificed. The spraying method of powder coatings was also investigated in this study. The additional moisture on the surfaces of the fine powder particles was found to reduce the resistivity of the powder so as to enhance the transfer efficiency during the corona spraying. On the other hand, a new spray gun design with alternative charging pattern could reduce the Faraday Cage effect during corona spraying of fine powders. In addition, it also showed large potential on improving the transfer efficiency of coarse powders. Finally, new processing techniques for functional powder coatings were developed. Utilization of dry blended catalysts could solve the problems of pre-curing and short shelf life associated with the conventional low-cure powder coatings. Other than that, the complicated heat-blending process for processing metallic color powder coatings can be replaced by a new bonding technique with utilization of liquid bonder. The strong bond between powder particles and metallic pigments provided by this new technique can solve the recyclability problem of the metallic color powder coatings during spraying. The discoveries from the thesis study contribute to further understandings of powder coatings. This study also provides useful suggestions for future developments of powder coating technologies