Electrical conductivity and gas sensitivity of Zn-Sb-O thick films

The thick film of Zn-Sb-O was prepared by coating the paste of nanoparticles mixture (Sb₂O₃:ZnO=1:3) on the alumina substrate, followed by sintering at 500-900 °C for 2 h in air. The electrical resistance and gas-sensing properties to benzene, alcohol and acetone of Zn-Sb-O films were found to be dependent on the change of phase structure caused by sintering temperature.     

Development of polyurethane elastomer composite materials by addition of milled fiberglass with coupling agent

Polyurethane elastomer composites were developed using milled fiberglass and their mechanical properties were studied. In particular, the organically chemical treatment of the milled fiberglass was investigated in detail. It was demonstrated that both strength and toughness of the resulting elastomer composites were improved considerably with the addition content of fiberglass. Furthermore, it was indicated that the optimal properties can be achieved by the proper addition of milled fiberglass that was chemically treated using coupling agent.     

Host/guest complex of Me-β-CD/2,2-dimethoxy-2-phenyl acetophenone for initiation of aqueous photopolymerization: Kinetics and mechanism

Methylated-β-cyclodextrin (Me-β-CD) was used to complex the photoinitiator, 2,2-dimethoxy-2-phenyl acetophenone (DMPA), yielding a water-soluble host/guest complex. The comparative studies demonstrated that the Me-β-CD complexed DMPA exhibited a high photoreactivity identical to the uncomplexed DMPA, while the CD complex obviously influenced the products of primary photolysis of DMPA and the photopolymerization kinetics due to the steric effect of CD on the subsequent initiation reactions. The photopolymerization rate of acrylamide can be described by the equation: R_p=K[2a]^0.62[M]^1.37[I]^0.5[Me-β-CD]⁰. The mechanism of polymerization was also discussed.     

On sorting triangles in a delaunay tessellation

In a two-dimensional Delaunay-triangulated domain, there exists a partial ordering of the triangles (with respect to a vertex) that is consistent with the two-dimensional visibility of the triangles from that vertex. An equivalent statement is that a polygon that is star-shaped with respect to a given vertex can be extended, one triangle at a time, until it includes the entire domain. Arbitrary planar triangulations do not possess this useful property which allows incremental processing of the triangles.This work was partially supported by the National Science Foundation's US-Italy Collaborative Research Program under Grant INT-8714578 and Information, Robotics, and Intelligent Research Grant IRI-8704781.     

Computerized conferencing for knowledge acquisition from multiple experts

The increasing complecity of many expert system application areas calls for the integration of the knowledge of multiple experts. The use of multiple experts introduces some interesting new problems during the process of knowledge acquisition. The problems are further complicated when the experts are geographically dispersed or unavailable for face-to-face interactions.

This article discusses the motivations for acquiring the knowledge of multiple experts, the problems related to knowledge acquisition, new issues that arise whens multiple experts interact, solutions that can be brought to bear in building multiple expert systems (particularly when experts are geographically dispersed), and new tools for knowledge engineers to use when dealing with multiple experts.     

Electrochemical Faceting of polycrystalline platinum in HF solutions

The electrochemical faceting of polycrystalline (pc) platinum yielding a (100)-preferred oriented electrode surface was accomplished in HF solutions by applying to the pc platinum electrode a square wave potential perturbation at 1 kHz in the 0.2 to 1.3 V range (vs rhe). SEM patterns of the resulting surfaces were also obtained. For HF concentrations up to 2 M no appreciable influence of the electrolyte concentration on the electrochemical faceting was noticed. Otherwise, the voltammetric response of the (100)-type preferred oriented platinum surface in the H-adatom potential range when compared to previously reported data resulted remarkably sensitive to the electrolyte composition. The discussion of results was based on the non-equilibrium adsorption conditions for anions under the periodic perturbation.     

Catalytic properties and electronic structure of copper ions in Cu-ZSM-5

The effect of ion exchange conditions, such as Si/Al ratio, precursor copper salt, pH and concentration of the solution, on the catalytic activity in SCR of NO by propane and on the electronic state of copper ions in Cu-ZSM-5 has been studied. The NO conversion in NO SCR by C₃H₈ has been found to reach a maximum value at Cu/Al ratio about 0.37–0.4 and remain constant at higher Cu/Al.

ESR and UV–vis DR spectroscopy have been used to elucidate stabilization conditions of copper ions in Cu-ZSM-5 zeolites as isolated Cu²⁺ ions, chain copper oxide structures and square-plain oxide clusters. The ability of copper ions for reduction and reoxidation in the chain structures may be responsible for the catalytic activity of Cu-ZSM-5. These transformations of copper ions are accompanied by the observation of intervalence transitions Cu²⁺–Cu⁺ and CTLM of the chain structures in the UV–vis spectra.     

Generalized difference control of parallel streams temperatures

A furnace with multiple parallel passes and multiple burners is commonly seen in petroleum refineries. In order to maintain the furnace running in a safe, stable, and high-efficiency state it is necessary to control the outlet temperatures of the multiple passes to be the same. Due to the fact that the process of the oil heating in such furnace is nonlinear, multivariable, time varying, has serious coupling among passes, has frequent dynamic changes and a large time delay, traditional control methods have trouble in controlling these temperatures, and some advanced control methods, including predictive control, adaptive control, and robust control, are usually too complex for convenient use. In this paper, a control technique, called differences control technique (DsCT), is proposed to distribute the stream flowrates such that the stream temperatures are as identical as possible. The principle of the proposed technique is explained and demonstrated, and the results of its application to a real-life petroleum refinery furnace are also reported. The DsCT technique has the following advantages: it does not need complicated design procedures, the controller structure is simple, it is easy to apply, and it can be canonically applied to furnaces with different number of passes.