High-Performance and Low-Cost Single-Switch Current-Fed Energy Recovery Circuit for ac Plasma Display Panel

A high-performance and low-cost single-switch current-fed energy recovery circuit (ERC) for an alternating current (ac) plasma display panel (PDF) is proposed. Since it is composed of only one power switch compared with the conventional circuit consisting of four power switches and two large energy recovery capacitors, it features a much simpler structure and lower cost. Furthermore, since all power switches can be switched under soft-switching operation, the proposed circuit has desirable merits such as an increased reliability, and low switching loss. Especially, there are no serious voltage notches across the PDP with the aid of gas discharge current compensation, which can greatly reduce the current stress of all inverter switches, and provide those switches with the turn on timing margin. To confirm the validity of the proposed circuit, its operation and performance were verified on a prototype for 7-in test PDP.     

Sensitivity of third- and higher-order filters

For any realization of a network function F(s) = N(s)/D(s), the sensitivities that can be most readily calculated are those of the coefficients in N(s) and D(s). A simple relationship is derived that enables one to calculate the root (pole and zero) sensitivities of F(s) in terms of the coefficient sensitivities. The root sensitivities, in turn, enable one to calculate the root pair Q and root frequency sensitivities, which can be used to characterize and compare different realizations of F(s). Application to 3rd- and 4th-order filters reveals formulations that are more elegant than those already known in the literature.     

Nonlinear feedback control and trajectory tracking of vehicle

This paper mainly studies nonlinear feedback control applied to the nonlinear vehicle dynamics with varying velocity. The main objective of this study is the stabilisation of longitudinal, lateral and yaw angular vehicle velocities. To this end, a nonlinear vehicle model is developed which takes both the lateral and longitudinal vehicle dynamics into account. Based on this model, a method to build a nonlinear state feedback control is first designed by which the complexity of system structure can be simplified. The obtained system is then synthesised by the combined Lyapunov–LaSalle method. The simulation results show that the proposed control can improve stability and comfort of vehicle driving. Moreover, this paper presents a lemma which ensures the trajectory tracking and path-following problem for vehicle. It can also be exploited simultaneously to solve both the tracking and path-following control problems of the vehicle ride and driving stability. We also show how the results of the lemma can be applied to solve the path-following problem, in which the vehicle converges and follows a designed path. The effectiveness of the proposed lemma for trajectory tracking is clearly demonstrated by simulation results.     

Photoreaction of gold ions from potassium gold cyanide wastewater using solution-combusted ZnO nanopowders

Photoreduction of gold ions from potassium gold cyanide wastewater was tried using the ZnO nanopowder which was synthesized by a unique solution combustion method (SCM). The SCM produced instantaneous high pressure and high temperature (1500–1800 °C) conditions which are desirable to obtain high quality ZnO nanopowders, even though it was not intentionally heated at higher than 100 °C during the synthesis reaction. The high crystalline quality of the ZnO nanopowder seemed to result in high efficiency of gold recovery compared to other commercial photocatalysts such as P-25 TiO₂ nanopowder (Degussa). The wastewater contains many kinds of ions such as K, P, Au, Na, Ni, Cu and Zn ions. Only the gold ions were selectively recovered out of these ions. The gold recovery efficiency of the SCM ZnO nanopowder was about 8.6 folds higher than that of the P-25 TiO₂ nanopowder. The very high selectivity of Au³⁺ ions could be explained by the reduction potential which is placed near the edge of valence band.     

Heat transfer in micropolar boundary layer flow near a stagnation point

Using the micropolar theory, a set of boundary layer equations are obtained for the two dimensional flow of an incompressible micropolar fluid near a stagnation point. The boundary conditions of isothermal and insulated wall are taken with VISCOUS DISSIPATION effects. Numerical results for the temperature distribution has been shown graphically for different values of the material parameters and Prandtl number.     

Chemical-looping combustion of syngas by means of spray-dried NiO oxygen carrier

Chemical-looping combustion (CLC) of syngas has a potential to generate power economically with achieving the inherent carbon dioxide capture. An oxygen carrier with high reactivity and excellent physical properties would make CLC technology more competitive. In this work, oxygen carrier with 70 wt% NiO was prepared by spray drying technique. The prepared oxygen carrier had excellent physical properties for fluidized-bed application of CLC process. The reactivity of the oxygen carrier in repeated reduction-oxidation was measured by thermogravimetric analyzer with simulated syngas. Oxygen carrier calcined at 1,100 °C showed high oxygen transfer capacity of 14.7 wt%, utilizing 98% of the transferable oxygen. Oxygen transfer capacity and oxygen transfer rate was increased with the increase of reaction temperature, and the highest oxygen transfer rate was observed when about half of the transferable oxygen reacted with syngas. The reduction rate of the syngas (mixture of H₂ and CO) appeared to be approximately the sum of the reaction rate of each fuel gas. The experimental results indicated that the spray-dried NiO oxygen carrier prepared in this work could be a good quality oxygen carrier for the CLC of syngas.     

Harmonization of global third generation mobile systems

The International Telecommunication Union launched the third-generation project in 1986 with the aim to provide global personal communication using an inexpensive mobile terminal that can truly facilitate communication "anywhere, anytime". In previous years, standardization activities toward IMT-2000 have accelerated toward concrete specifications. By June 1998, a total of 15 proposals from around the world had been submitted to the ITU as radio transmission technology candidates. Since then, the 3G standardization landscape has seen many changes-a steady progression of the convergence process. This article provides a comprehensive overview of the worldwide harmonization efforts on the standardization of third-generation terrestrial mobile communication systems. The status, as of October 1999 when this article was written, of the technical specifications within 3G partnership projects are also summarized.     

Microstructure formation in chalcogenide thin films assisted by thermal dewetting

The spontaneous formation of self-assembled and/or self-organized patterns is a fundamental and technologically significant topic. This process is achieved via a phenomenon called dewetting, should it be thermally induced, or caused by laser exposure. Although dewetting seems to be a well-known phenomenon for metallic and polymeric thin films, no proper investigation regarding glassy thin films seems to have been done. Thus, in the present study we try to elaborate on the process of thermal dewetting applied to glassy thin films of the system Ag_x(As₂₀S₈₀)_100?x.