The application of transmission-line modelling to the simulation ofan induction motor drive

The simulation of a complete induction motor drive is presented. The entire network is modelled using the transmission-line modelling (TLM) technique. The network is split into three sections which are solved independently and are joined together by link transmission-line models. Advantages of this approach are the explicit nature of the algorithm which remains unaltered irrespective of the network topology, unconditional stability, and straightforward modelling of switching elements. Results are presented for a complete drive which illustrate the capabilities and flexibility of the simulation technique     

Precision measurements of the degradation of semiconductor optoelectronic components

A method, apparatus and results of measurements of the degradation of semiconductor optoelectronic components (light-emitting diodes and photodiodes) are described. The difficulties that occur in such investigations are pointed out. Translated from Izmeritel'naya Tekhnika, No. 10, pp. 33–35, October, 1996.     

Dissolution Behavior of Griseofulvin Solid Dispersions Using Polyethylene Glycol, Talc, and Their Combination as Dispersion Carriers

Griseofulvin solid dispersions were prepared using polyethylene glycol 6000 (PEG), talc, and their combination as carriers by the solvent method. The dissolution of griseofulvin from these dispersions was studied. It was found that in these carriers the drug dissolution rate was a function of drug loading. The dissolution rate from dispersions prepared using PEG was similar to that from PEG/talc dispersions, especially at a low percentage of drug loading. Dispersions of PEG and PEG/talc provided dissolution rates faster than those from dispersions of talc. The incorporation of talc in PEG yielded dispersions with properties of less tackiness and ease for handling. Dissolution kinetics, based on the Hixson-Crowell equation, was used to determine the characteristics of griseofulvin particles in dispersions. Linear relationships were obtained for PEG and PEG/talc dispersions that indicated the presence of a uniformly sized monoparticulate system, whereas deviation from linearity was observed for talc dispersions. This appeared to be a multiparticulate system in which particles were present as free form and adsorbed form on the surface of talc.     

Electrochemical intercalation in NiOx thin films

In this work we investigated the mechanism of the electrochemical intercalation reactions in rf sputtered nickel oxide thin films electrodes by two techniques: mechanical stress change measurements by means of an optical technique and mass changes using an electrochemical quartz microbalance (EQCM). The experiments were performed in alkaline electrolytes containing cations of the first column of the periodic table. Reversible mass and volume changes were observed. In order to explain these experimental results, an exchange reaction is proposed, in which the oxidation process is accompanied by the deinteractional of a relative large number of “light” cations, simultaneously with the intercalation of a smaller number of heaviest cations.     

Analogue micropowered log-domain tone controller for auditoryprostheses

A micropower tone-control circuit comprising two first-order log-domain filters and a subtractor built with MOS transistors in weak inversion is described. The tone-controller is capable of providing bass cut/boost and treble cut operations. This circuit is being used in new designs of a conventional (acoustic) hearing-aid and cochlear implant     

Mixing in processing of thermoplastics by extrusion

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 8, pp. 9–11, August, 1993.     

How far is it to the nearest hospital? Calculating distances using the Statistics Canada Postal Code Conversion File

This report demonstrates how to calculate distances between points described in terms of latitude and longitude, using the Postal Code Conversion File (PCCF) and other files available from the Geography Division of Statistics Canada. Examples based on hospital data show how the results can be summarized in the form of tables, figures, or maps. Aerial distance to the nearest hospital is a crude but objective indicator of geographic accessibility to hospital services. Distances were calculated between enumeration area centroids for the population and blockface or enumeration area centroids for the hospitals. The median aerial distance to the nearest hospital facility in Canada was less than 3 km, while the mean distance was about 6 km. For teaching hospitals, the median aerial distance was a little less than 30 km, while the mean distance was a little more than 90 km. As most health files for administrative and research purposes contain postal codes, these techniques have potentially wide application.