ROTOR RESISTANCE ESTIMATION FOR SLIP ADAPTATION IN SENSORLESS INDUCTION MACHINE DRIVES

ABSTRACT

This work presents a rotor resistance estimation algorithm. The estimation process is based on a recursive least squares method. It is applied to a speed sensorless induction motor drive scheme in order to implement slip adaptation. A discrete approach is considered in which an induction motor model written in form of difference equations is used by the estimation algorithm. All the associated mathematical developments are shown. Simulation results are used to verify the performance of the proposed rotor resistance estimator.     

Evaluation of calibration methods for a helicopter-borne microwave scatterometer

The French frequency modulated continuous waves (FMCW) scatterometer ERASME mounted on small helicopter or aircraft has been designed as dualfrequency (C and X bands) and dualpolarization (HH, VV) to investigate simultaneously the vegetation and the soil responses in radar backscattering. It is operated as a forward looking radar with a large elevation beamwidth (± 10° at 3 db) to observe easily the same surface target over a large range of incidence angles during a single flight. By this ability, ERASME is a complementary research tool for intercalibration of airborne and spaceborne imaging Synthetic Aperture Radars like Radarsat and ASAR and has to be well calibrated in every configuration, both absolutely and relatively for comparisons at different incidence angles.

This paper evaluates different calibration methods to be applied to such an instrument. Absolute calibration within 1 dB is easily obtained by external calibration using metallic corner reflectors. But this method remains insufficient to get the antenna elevation aperture which is essential on natural distributed targets for antenna pattern correction, due to the severe constraint of a narrow azimuthal beam and flight parameters (pitch, roll, altitude) varying quickly in time and range.

The external calibration is strongly improved by using a statistical analysis of data obtained over natural targets which analyses the correlation between the processed data and the recorded flight parameters. This method appears promising, but its application on natural targets with random variations need specific statistical properties of the data set. It is operative for high antenna setting (here 38° incidence angle) and mostly over bare soils, with low of σ⁰ variances and σ² correlation length of the order of the correlation length of pitch. It provides the aperture range around the antenna axis and an accuracy of 0.5 dB upon erσ⁰ is achieved providing the antenna pattern correction are done.     

Kaolin from Sultan-Uvaiskoe Deposit in Ceramic Production

It is demonstrated that the Sultan-Uvaiskoe deposit (Uzbekistan) is a promising source of high-quality kaolin for production of fine ceramics and refractories.     

The influence of breed on the organoleptic characteristics of Zamorano sheep’s raw milk cheese and its assessment by instrumental analysis

The aim of this study was to investigate the effects of three different somatic cell count (SCC) values on the sensory characteristics of sheep’s milk cheeses from the Castellana and Churra breeds (allowed for Protected Designation of Origin Zamorano cheese manufacture) and the Assaf breed (foreign), determined by typical consumers and instrumentally. The results show that the sensory characteristics of hardness, intensity of taste, and pungency reflect a significant influence of the SCCs of the original milk whereas breed significantly affects colour intensity and hardness (Warner‐Bratzler maximum shear force; WBSF). The instrumental parameters most closely related to the assessments of the typical consumers were WBSF and the value of a*, for hardness and colour respectively.     

Operating experience with lubricating oils in diesel locomotive engine

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 10, pp. 21–22, October, 1988.     

Multilingual Document Production From Support for Translating to Support for Authoring

In this paper, we look at the current scenario in multilingual documentation generation and the types of tools currently being used in support of the translation task, and discuss their shortcomings. We examine emergent trends in the document industry, observing a reorganisation of the workflow which mirrors a shift of attention from translating to authoring and from the ergonomics of post-editing the target text to the ergonomics of producing the source text. We argue that these trends invite the design and development of new tools for the task of producing multilingual texts, and that multilingual generation provides the appropriate technology, shifting attention to an even earlier stage in the authoring process, that of specifying the semantics of the text to be produced. We describe a prototype system which exploits this technology to meet the expressed needs of authors and translators by supporting them in the drafting of multilingual instructions. We suggest that, in the future, a single platform to support multilingual documentation should integrate translation-oriented tools and generation-based tools to be employed as appropriate by different types of users (translators and authors) in different circumstances.     

Effects of cold and warm blood cardioplegia assessed by myocardial pH and release of metabolic markers

The optimal temperature of blood cardioplegia remains controversial. Interstitial myocardial pH was monitored online with a probe that was inserted in the anterior wall of the left ventricle. Venous pH, lactate production, and creatine kinase and troponin T release were measured in coronary sinus blood obtained in 14 dogs after ischemic arrest periods of 5, 10, 20, and 40 minutes with warm (n = 7; mean myocardial temperature, 35 degrees +/- 2 degrees C) and cold (n = 7; mean myocardial temperature, 12 degrees +/- 1 degree C) blood cardioplegic protection. Blood cardioplegic solution was delivered at a rate of 100 mL/min during the 10 minutes between each ischemic arrest. The interstitial myocardial pH decreased significantly (p < 0.05) from 7.1 +/- 0.3 to 6.53 +/- 0.3 after ischemia in animals perfused with warm blood cardioplegia and from 7.04 +/- 0.3 to 6.64 +/- 0.1 in those receiving cold blood cardioplegic protection; however, the difference between the groups was not significant (p > 0.05). Lactate production and creatine kinase and troponin T release increased significantly after ischemia, but there was no difference in the changes between the warm and cold blood cardioplegia groups. In conclusion, ischemia caused significant changes in all variables measured, and these changes were directly proportional to the duration of ischemia. However, there was no significant difference (p > 0.05) in the myocardial metabolic changes between the warm and cold blood cardioplegia groups in terms of the duration of ischemic arrest studied.(ABSTRACT TRUNCATED AT 250 WORDS)