Surface treatment of titanium dioxide nanopowder using rotary electrode dielectric barrier discharge reactor

Titanium dioxide (TiO2) nanopowder (P-25;Degussa AG) was treated using dielectric barrier discharge (DBD) in a rotary electrode DBD (RE-DBD) reactor.Its electrical and optical characteristics were investigated during RE-DBD generation.The treated TiO2 nanopowder properties and structures were analyzed using x-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR).After RE-DBD treatment,XRD measurements indicated that the anatase peak theta positions shifted from 25.3° to 25.1°,which can be attributed to the substitution of new functional groups in the TiO2 lattice.The FTIR results show that hydroxyl groups (OH) at 3400 cm-1 increased considerably.The mechanism used to modify the TiO2 nanopowder surface by air DBD treatment was confirmed from optical emission spectrum measurements.Reactive species,such as OH radical,ozone and atomic oxygen can play key roles in hydroxyl formation on the TiO2 nanopowder surface.     

Two-degrees-of-freedom dead-beat control system with robustness

This paper deals with the design of a two-degrees-of-freedom (TDF) dead-beat controller with both optimal robustness and minimum settling time. Based on the parametrization of all stabilizing TDF controllers, optimal robustness and minimum-time control are achieved simultaneously. The minimum-time dead-beat control is constructed for arbitrary real-rational reference input. At the same time, optimal robustness is achieved under the constraint that the error between reference input and output asymptotically vanishes for any plant perturbation that does not violate the internal stability. It is proved that under the same robustness criterion, irrespective of its length of settling time, the optimal robustness of the TDF system is always superior to that of the one-degree-of-freedom (ODF) system as long as its settling time is finite, and they become identical only when the settling time of the ODF system goes to infinity. A numerical example is given to illustrate the theoretical results.     

An application of Markov potential theory to Markovian decision processes

The aim of this paper is to identify the denumerable stochastic systems which have an optimal strategy, namely, to give general sufficient conditions of the existence of an optimal strategy for denumerable Markovian decision processes. The aim is accomplished by using Markov potential theory and showing the range of the validity of a method to find an optimal strategy called Howard's technique. Since Markov potential theory helps to characterize the properties of evaluations of strategies on such processes, it plays an important role to find the sufficient conditions mentioned above

For Markov potential theory, new concepts are introduced such as absorbable chains, quasi-potentials, etc., and using them, sufficient conditions for the existence of a solution of the equation x = f+Px are generalized to the one's for cyclic chains and multi-chains

The results obtained in this paper are as follows : if a system represents a strong Markov chain for any strategy, then there exists an optimal strategy with respect to the total or the mean expected earnings, and for any stochastic system there exists an optimal strategy with respect to the discounted total expected earnings.     

KINETICS OF BIOETHANOL PRODUCTION FROM WHEAT MILLING BY-PRODUCTS

An overview of the potential application of wheat milling by‐products as substrate for bioethanol production is presented. In order to select a suitable microorganism, model fermentations were conducted using glucose and dry baker's yeast. The overall ethanol yield was nearly stable (ca. 0.35 g/g), independent of mash glucose concentration; mashes with 100 g glucose/L resulted in an overall ethanol productivity of 3.48 g/L·h. Slurries containing low‐grade wheat flour (LG) (100, 200 or 300 g/L) were used for simultaneous saccharification and fermentation (SSF) with Zymomonas mobilis. Fermentation performance was evaluated based on ethanol concentration (P), productivity (Q_v), yield (Y_P/S), production rate (Q_p) and glucose consumption rate (Q_s). Mashes containing 200 g LG/L produced about 52 g ethanol/L, with Q_vof 2.17 g/L·h. Based on the relatively high fermentation rate of LG, reaching peak ethanol productivity within ca. 9 h of SSF, considerable savings on fermentation time was achieved. Using Z. mobilis for LG fermentation, P was about 30% higher than that obtained with Saccharomyces cerevisiae.     

Transformation of a continuous time-invariant linear system into a discrete one

A discrete-time time-invariant linear system (DILS) is considered which has resulted from the discretization of a continuous-time time-invariant linear system (CILS) by the zero order hold. In this system, the system and input matrices are given by exp(AT) and $ where A and B are the system and input matrices of the CILS, and T is a sampling interval. Since they involve the matrix exponential, their computations are not easy.

First, on the assumption that the Kalman canonical form of the CILS is sought, a formal Kalman canonical form of the DILS is determined. Second, with the use of this form and the decomposition of A into the projectors onto the generalized eigenspaces, an algorithm is presented which computes the system and input matrices of the DlLS.     

Mn和V对TiAl合金热腐蚀的影响

Mn和V对TiAl金属间化合物在900℃(Na，K)2SO4熔盐中热腐蚀行为的影响有所不同．TiAl合金中加入Mn后，最外层的腐蚀产物为以Al2O3为主、另有少量TiO2的混合物；内层是Al，Ti和Mn的混合氧化物以及Ti的硫化物．加Mn在一定程度上减弱了TiAl合金的耐蚀性TiAl和TiAl-Mn合金中加入V后耐蚀性明显变差，最外层腐蚀产物以TiO2为主，并含有少量Al2O3和微量的V2O5，腐蚀层中的V2O5引起Al2O3的酸性溶解，因而不能形成保护性的Al2O3层，形成的TiO2和Al2O3混合膜的黏附性差，较易剥落。     

Collagen as the Major Edible Component of Jellyfish (Stomolophus nomural)

The mesogloea and skin of a common edible jellyfish, Stomolophus nomurai, were characterized with respect to amino acid composition and compared with a commercially salted jellyfish. Then the mesogloea was digested with pepsin at 3°C for 48 hr and its solubilized protein was isolated and subjected to biochemical analyses. These composite results have shown that the major edible component of jellyfish was the connective tissue protein, collagen, characterized by its high content of hydroxylysine and its glycosides.     

Preparation of Bi4Ti3O12 Powders in the Presence of Molten Salt Containing LiCl

The reaction between Bi₂O₃ and TiO₂ in molten LiCl-KCl was examined with special emphasis on the reaction mechanism and the size of Bi₄Ti₃O₁₂ particles. The oxides reacted with LiCl to form an intermediate compound, which changed into Bi₄Ti₃O₁₂ on extended heating. Potassium chloride retarded the reaction between the oxides and LiCl and promoted the change from the intermediate compound to Bi₄Ti₃O₁₂. Bi₄Ti₃O₁₂ particles prepared in the flux were platelike, irrespective of the preparation conditions, but their size depended on reaction temperature and time, the ratio of LiCl to KCl, and the amount of flux.