A study of microwave transmission,reflection, absorption,and shielding effectiveness of conducting polypyrrole films

Microwave transmission, reflection, and absorption behavior and the shielding effectiveness of electrochemically synthesized polypyrrole films with dc conductivities ranging from 0.001 to 50 S/cm are presented. Results show that the electrical conductivity of the doped polypyrrole films has a significant effect on transmission, reflection, and absorption of microwaves. Heavily doped, conducting films were highly reflective, whereas lightly doped, semiconducting films had very high transmission. Intermediate conductivity polypyrrole samples were highly absorptive. The agreement between experimental data and theoretical modeling provided confidence to extend the modeling to include the effect of sample thickness on the transmission, reflection, and absorption properties of films with a wide range of conductivity values, hence, providing valuable information for the design of microwave devices and fundamental understanding of the material properties. A method of measuring the far-field sheilding effectiveness of polypyrrole films is also presented. Results of shielding experiments indicated the potential for such applications. © 1994 John Wiley & Sons, Inc.     

Inhibiting effects of some synthesized organic compound on the corrosion of St-3 in 0.1N H2SO4 solution

The inhibiting properties of two synthesized metals (alkyl)-2-hydroxy benzene sulfonate compounds have been studied on the corrosion of steel (St-3) in aerated 0.1N H₂SO₄ solutions by potentiodynamic polarization (dc) technique and electrochemical impedance spectroscopy (ac). The polarization curves indicate that the inhibitors are mixed-type. The impedance increases with inhibitors concentration. Low difference in inhibition efficiencies of two compounds for the corrosion of St-3 steel could be explained by high similarities of their structures. Results obtained by both electrochemical methods are in relatively good agreement.     

A mathematical model for designing reconfigurable cellular hybrid manufacturing-remanufacturing systems

The process chain of product regeneration includes the removal of excess weld material, which is called re-contouring. Like all machining processes, re-contouring influences the surface integrity and therefore the functional performance of the regenerated parts. One important aspect of surface integrity is the surface topography, especially for blades in turbine engines due to the flow losses. This paper investigates the fundamental influence of cutting conditions, tool geometry and weld shape on the surface topography after 5-axis ball nose end milling of welded Ti-6Al-4V parts. It is shown by experiment and simulation that apart from the cutting parameters also the chipping of the cutting edge and the tool runout highly influence the surface topography. The size of the weld and the tool compliance primarily influence the tool deflection and the appearance of chatter vibrations.     

Influence of commercial corrosion-inhibiting compounds on the atmospheric corrosion of the magnesium alloys EV31A,WE43B,ZE41A and pure magnesium

The influence of four commercial corrosion-inhibiting compounds on the atmospheric corrosion of EV31A, WE43B, ZE41A and pure Mg was studied at two hot, humid, tropical sites for test periods of 3–12 months. LPS 3 and AMLGuard significantly reduced the corrosion rates, with AMLGuard being most effective with inhibition efficiencies above 85%. In contrast, Ardrox 3961 and LPS 2 were ineffective with typical corrosion rates comparable with those of the bare alloys. Corrosion inhibition was tentatively attributed to protective durable barrier films formed by chemical adsorption for LPS 3 and AMLGuard.     

Ensuring the Stability of Operation of the Ethylene Region of a Chemical and Technological Complex for Processing Gases of Cracking and Pyrolysis by Taking into Account the Dynamics of the Processes

Theoretical Foundations of Chemical Engineering - This work studies the dynamics of the processes of the ethylene region of a chemical–technological complex (CTC) and the reasons for the...     

On the rate of convergence of the asymptotic expansion for the ergodic distribution of a semi-Markov (s, S) inventory model

A stochastic process is considered that describes the so-called (s, S) inventory model. The asymptotic behavior of the ergodic distribution of the process is investigated. It is established that the ergodic distribution of the process on the interval [s, S] tends to the uniform distribution for sufficiently large values of the parameter β = S − s, and the convergence rate is estimated.     

Source Rock Evaluation of The Eocene Shales in the Gökçesu Area (Bolu/Turkey)

Abstract

Hydrocarbon potential of oil shale samples from the Gökçesu basin in Bolu, Turkey, was evaluated on the basis of organic geochemical, organic petrographic, gas chromatography, and thin-layer chromatography techniques. Organic materials were found to be oil-producing type (Type I and II kerogen). Thermal maturities, that indicate diagenetic and early mature oil formation stage, were determined with pyrolysis (Tmax), production index (PI), and spore color index (SCI) analyses. The amount of organic material ranging between 0.21 and 15.89% reveals that the unit has variable source rock potentials from weak to perfect. The productivity of the basin was probably high and organic matter preservation was enhanced by a stratified water column. As the basin began to fill with sediment and become shallower, TOC and HI values declined, as the basin water was better oxygenated and preservation conditions declined. On the basis of geologic data, organic geochemical analyses and organic petrographic studies, organic facies of Eocene shales is of AB and B types.