Pore size control of porous silica by sol-gel process

Porous silica glass was prepared by sol-gel process from tetraethoxysilane (TEOS). The effects of solvents (water, ethanol), drying condition, heat treatment temperature on specific surface area and pore size distribution of porous silica were investigated. Gelation process accelerates with an increase of H₂O content, while retards with the increase of ethanol amount. Structure changes during heat treatment were studied by means of DTA, XRD. TEM micrographs show that the gel particles shrink after heated at 500°C, thus the average pore size decreases.     

Finite Element Analysis of a Moving Boundary Value Problem

A finite element formulation and the solution of a set of nonlinear coupled heat and mass transfer equations for a two-phase system with a moving evaporation interface is presented. The interface condition takes into account the moisture transfer balance at the moving boundary. The finite element results were compared with existing results for a single phase system for model validation. In the two-phase system, the movement of evaporation front has an appreciable effect on the temperature and moisture distribution inside the porous medium during drying. The effect of the nondimensional heat of vapourization parameter γ on the evaporation front, temperature and moisture distribution in porous medium was studied. The higher the value of γ, the slower is the movement of the evaporation front. The temperature decreased and the moisture content increased as the nondimensional vapourization parameter γ increased. This model has potential applications in studying the heat and mass transfer characteristics in food and biomaterials.     

Mobility modeling, location tracking, and trajectory prediction inwireless ATM networks

Wireless ATM networks require efficient mobility management to cope with frequent mobile handoff and rerouting of connections. Although much attention has been given in the literature to network architecture design to support wide-area mobility in public ATM networks, little has been done to the important issue of user mobility estimation and prediction to improve the connection reliability and bandwidth efficiency of the underlying system architecture. This paper treats the problem by developing a hierarchical user mobility model that closely represents the movement behavior of a mobile user, and that, when used with appropriate pattern matching and Kalman filtering techniques, yields an accurate location prediction algorithm, HLP, or hierarchical location prediction, which provides necessary information for advance resource reservation and advance optimal route establishment in wireless ATM networks     

A study on the anodic protection of Titanium evaporators in Al2(SO4)3 solution

The feasibility of the anodic protection of titanium evaporators in Al₂(SO₄)₃ solution was studied by the measurement of polarization curves, weight loss, solubility of passive film and AC impedance. The protection parameters and efficiency were determined. In addition, the practical technology of anodic protection was studied by screening reference electrodes and auxiliary cathodes. Throwing power was also measured. Four rows of tube-type evaporators of titanium have been anodically protected in situ. Field tests lasting more than one year show satisfactory results.     

A maximum torque control with a controlled capacitor for asingle-phase induction motor

This paper presents a new method to achieve a maximum torque for a single-phase induction motor. An AC adjustable capacitor using an electronic switch in parallel with a capacitor is proposed. The capacitor is short-circuited in a different period by an electronic switch during each cycle to vary the effective value of the AC capacitor. Two new optimization algorithms, which obtain a maximum starting torque by adjusting the effective capacitor, are proposed. No starting capacitor or centrifugal switch is used here. A theoretical analysis, and simulated and experimental results are presented in this paper     

The effects of plasma etching induced gate oxide degradation onMOSFET's 1/f noise

The effects of the plasma etching process induced gate oxide damages on device's low frequency noise behavior are investigated on MOSFET's fabricated with different field plate perimeter to gate area ratio antennas. Abnormal 1/f noise spectrum with a shoulder centered in the frequency range of 100 and to 1 kHz was frequently observed in small geometry devices, and it is attributable to a nonuniform distribution of oxide traps induced by plasma etching process     

COIL中BHP浓度对发生O_2(~1△)的影响

本文实验研究了BHP的浓度对产生O2（1△）的影响。实验结果表明：当BHP浓度大于3.5M时，Cl2利用率以及O2（1△）的产率将不依赖于BHP浓度的变化而变化，同时，实验结果表明，使用低浓度的BHP对COIL的操作是可行的。     

Bisensors for amino acids

Two kinds of biosensors for amino acids (one with nonspecific enzyme as bioelement, the other with specific enzyme(s) as bioelement), including their principles, applications, recent researches and future trends were discussed in detail. 61 references were given. A part of work for gaining Ph. D in chemical and biochemical application at FPMs (Mons, Belgique) Synopsis of the first author Xia Jinlan, Male, born in 1963, now at Facult’e Polytechnique de Mons, Belgique     

Optimality of the sequential probability ratio test fornonstationary observations

Bayesian analysis is used to show that Wald's sequential probability ratio test with varying thresholds is optimal for the nonstationary situation, where the observed samples are independent but not identically distributed. Some important properties useful for the design of the test thresholds are discussed. Wald's lower bound, generalized to the nonstationary situation, is also presented. The results have important applications in situations where the observed signal is time-varying. such as in radar signal processing, image processing, and spread spectrum communications     

Verbessertes Widerstandsgesetz für Stufendiffusoren

Zusammenfassung Es wird ein allgemeines Widerstandsgesetz für Stufendiffusoren hergeleitet, bei dem die Widerstandszahl den Zusatzverlust gegenüber den Verlusten der bis zum Kontursprung reichenden fiktiven Kanal- bzw. Rohrstr?mungen in der Zu- und Abstr?mung beschreibt. Unter vereinfachenden Annahmen reduziert sich dieses Gesetz auf die bekannte Carnot-Formel. Insbesondere wird dabei der Anteil des Zusatzverlustes, der vom Unterdruck an der Stufe und von der Wandschubspannungs?nderung unmittelbar hinter der Stufe herrührt, vernachl?ssigt. Die Berücksichtigung dieses Anteils führt zu einem gegenüber der Carnot-Formel verbesserten Widerstandsgesetz. Herrn Prof. Dr.-Ing. Martin Fiebig zum 60. Geburtstag