Nonlinear inverse problem of reconstructing transport coefficients

The inverse coefficient problem for the quasilinear heat-conduction equation is solved numerically.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 6, pp. 909–915, December, 1985.     

Analysis of the effect of polypyrrole synthesis conditions on its capacity to reduce hexavalent chromium

This paper reports the capacity of polypyrrole to reduce toxic hexavalent chromium (Cr(VI)). The influence of using different electrolytes during the polymer's synthesis has been studied. To improve the reduction of Cr(VI), the parameters considered were the polypyrrole morphology and the amount of conducting polymer. Polypyrrole obtained by cyclic voltammetry at a low sweep rate using KBr as supporting electrolyte showed better performance for Cr(VI) reduction compared to coatings obtained by constant potential or cyclic voltammetry at high sweep rates.     

Alternative market arrangements for technology transfer

With the rapid expansion of markets for telecommunications services and equipment, both national and international, one sees an increasing frequency of alliances in which each of two firms seeks to use the other to complete its portfolio strengths. Often this combination enables firms to achieve the product differentiation that seems to be the key to competitive advantage in modern telecommunications markets. This alliance may take the form of a « joint venture », which in the paper includes as limiting cases a subsidiary wholly owned by one firm, a technology licensing arrangement, and direct exporting. The model of such a venture presented here, although simple, is rich enough to illustrate the influence of four types of factors on the negotiations that set up the venture: demand, costs, risk, and regulatory constraints. We characterize the sets of acceptable and efficient arrangements, under various assumptions about exogeneous factors. The partners must choose among these by some form of bargaining.     

System analysis of the efficiency of turbocompressor units for the gas and oil industry

Schemes are analyzed for turbocompressor installations (TCI) with a gas turbine drive (GTD) for collecting and transporting petroleum gas (PG) and natural gas (NG). The makeup of the equipment for an NG TCI setup based on a GTD of the aircraft or ship type is considered. Energy characteristics of the NG TCI and PG GTD are provided. A procedure for energy analysis of the TCI is developed. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 8, pp. 44–48, August, 2007. From the editor. According to the certificate of the international bureau Marquis Who’s Who (USA) the biography of the author of this article V. P. Parafeinik as a specialist in the field of oil and gas equipment is included in the annual catalog Who’s Who in the World (24, p. 1954) for 2007.     

Modeling Microwave Vacuum Drying Kinetics and Moisture Diffusivity of Carrot Slices

Carrot slices of 3.5 mm thickness were dried in a laboratory microwave vacuum dryer at five different microwave power density levels of 2, 4.66, 7.33, 10, and 12.66 W/g and at three vacuum chamber pressure levels of 6.66, 19.98, and 33.3 kPa to 4-6% d.b. moisture content. Inside the dryer the sample holding plate was rotated with the speed of 4 rpm for uniform microwaves application. The drying rates were increased with the increase in microwave power density at all pressure levels and the Page model was found to be the most suitable model to predict the drying behavior of carrot slices at all process conditions. The Page model drying rate constant (k, min^-1) showed high correlation with microwave power density at constant pressure by a power law equation and showed a logarithmic relationship with the microwave power density and pressure. Similar to the drying rate constant, the average moisture diffusivity at constant pressure was found to be function of microwave power density by power law equation as well as was also dependent on the power density and pressure by a logarithmic relationship.     

Percutaneous Absorption Enhancement by Nonionic Surfactants

The influence of nonionic surfactants (polysorbates) on hydrocortisone penetration through hairless mouse skin in vitro has been determined. Permeation was quite slow from purely aqueous media containing surfactants following finite dose application. However, if the vehicle contained high propylene glycol concentrations (40% or more), inclusion of a surfactant increased permeation rate significantly. Similar effects were noted following application of a large donor volume (infinite dose). Synergism was attributed to enhancement of surfactant absorption by the stratum corneum leading to changes in skin barrier resistance. With vehicles containing a surfactant, penetration was higher after finite dose application due to compositional changes within the vehicle.