DESIGNING 2 POLE AND 2/4 POLE WINDINGS BY THE SIMULATED ANNEALING METHOD

ABSTRACT

The object of the present paper is to explore the possibility of using simulated annealing procedures to determine multi-speed three phase windings. It is limited to the very simple case of p/2p polarities. The program has yielded the very well known solutions; thus, research may proceed towards more difficult problems.     

Subspace model identification Part 2. Analysis of the elementary output-error state-space model identification algorithm

The elementary MOESP algorithm presented in the first part of this series of papers is analysed in this paper. This is done in three different ways. First, we study the asymptotic properties of the estimated state-space model when only considering zero-mean white noise perturbations on the output sequence. It is shown that, in this case, the MOESPl implementation yields asymptotically unbiased estimates. An important constraint to this result is that the underlying system must have a finite impulse response and subsequently the size of the Hankel matrices, constructed from the input and output data at the beginning of the computations, depends on the number of non-zero Markov parameters. This analysis, however, leads to a second implementation of the elementary MOESP scheme, namely MOESP2. The latter implementation has the same asymptotic properties without the finite impulse response constraint. Secondly, we compare the MOESP2 algorithm with a classical state space model identification scheme. The latter scheme, referred to as the CLASSIC algorithm, is based on the Ho and Kalman realization scheme and estimated Markov parameters. The comparison is done by a sensitivity study, where the effect is studied of the errors on the data on the calculated column space of the shift-invariant subspace. This study demonstrates that the elementary MOESP2 scheme is more robust with respect to the errors considered than the CLASSIC algorithm. In the third part, the model reduction capabilities of the elementary MOESP schemes are analysed when the observations are error-free. We demonstrate in which sense the reduced order model is optimal when acquired with the MOESP schemes. The optimality is expressed by the difference between the 2-norm of the errors on the state (or output) sequence of the reduced-order model and the 2-norm of the matrix containing the rejected singular values being as small as possible. The insights obtained in these three parts are evaluated in a simulation study, and validated in this paper. They lead to the assertion that the MOESP2 implementation allows identification of a compact, low-dimensional, state-space model accurately describing the input -output behaviour of the system to be identified, while making use of ‘perturbed’ input-output data. This can be done efficiently.     

Comparison theorems for set stability of differential equations

Set stability and uniform set stability of differential equations involve known specific bounds on solutions of the differential equations under consideration. Comparison theorems are presented giving sufficient conditions for these forms of stability. The conditions include the existence of a Liapunov-Like function and the set stability of a scalar differential equation. Examples are given to demonstrate the method.     

MODELISATION D'UN SECHOIR SOLAIRE A POISSONS FONCTIONNANT EN CONVECTION NATURELLE

A mathematical model of the behaviour of a fish solar dryer has been described. This model has allowed an optimization of the design of this dryer (solar-chimney area and height, insolator area, etc...). The natural convection had to pulse drying air inside apparatus, whose capacity should be 30 kg of fresh fish.

Then the dryer has been built in National Fishing School of Anjouan (Comores Island). The first results mean a good fit between theoretical and experimental results.

The air-insolator, used for air heating, is a porous type, made with blacked coco fibers, crossed by the drying air. This local material is confirmed as a good thermic interface.

The most sensitive parameter, on the drying time, is the thickness of the fish slices. The choice of the fish quality is also very important: each different fish is characterized by one or several specific value of the water diffusivity constant, D_m. The model uses experimental values for the calculation.

Then the Fick's diffusion equation may be solved by decomposition of the moisture content inside fish slice (Fourier analysis).

Un modeéle matheématique du comportement d'un seéchoir solaire, destineé aà seécher du poisson, a eété eécrit. II a permis d'optimiser au mieux la geéomeétric de ce seéchoir qui a pu eêtre construit sur le site de I'eécole Nationale de peêche d'Anjouan aux Comores. II s'agit d'un seéchoir fonctionnant grace aà la convection naturelle, et dont la capacite est d'environ 30 kg.

L'air de seéchage est chauffeé par un capteur solaire de type absorbeur poreux, reéaliseé en bourre de noix de coco noircie. Le choix de ce mateériau local est bien suÛr volontaire; il s'est par ailleurs aveéreé comme un excellent milieu d'eéchange thermique.

Le parameètre le plus sensible sur la dureée de sechage est l'eépaisseur des filets de poisson. La qualiteé du poisson est aussi un choix important, chacun posseédant une constante de diffusiviteé de l'eau, D_m, bien speécifique. Le modeèle utilise les valeurs expeérimentales de cette constante. L'eéquation de Fick, qui reégit la migration de l'eau dans un mateériau poreux, peut alors eâtre reésolue en utiiisant une deécomposition en seérie de Fourier, de la reépartition de l'eau dans les tranches de poisson.     

DESIGN AND TUNING OF A FUZZY CONTROLLER FOR INDOOR AIR QUALITY AND THERMAL COMFORT MANAGEMENT

This paper presents the development and testing of a multi objective fuzzy controller. It is dedicated to the control of thermal comfort and indoor air quality while minimising energy consumption and reducing instabilities are other constraints for this controller. After a brief introduction on the difficult task of indoor climate control, the test cell and its corresponding model is described in the second section. The model has been developed within TRNSYS. Section 3 describes the architecture of the fuzzy controller applied to these control objectives in the test cell. A hierarchical architecture has finally been selected since it is a very flexible architecture and it results in reducing the total number of fuzzy rules. The rule optimisation technique, based on genetic algorithms is also presented in the third section. Simulation results are finally presented. They prove that, after optimisation, the fuzzy controller greatly outperforms a typical ON-OFF controller on all control criteria. Energy consumption is in particular reduced by more than 10%. The fourth section of this chapter presents field experiments among 20 subjects of both ON-OFF control and fuzzy control. If major differences are not observed on the thermal comfort and indoor air quality point of view, these experiments however illustrate the importance of on-line tuning of specific fuzzy rules.     

Nutritional Value of Veal Bone Hydrolysate

Industrial veal hydrolysate was produced enzymatically for possible use as a gelatin-replacing ingredient for human consumption. Protein digestibility and nutritional value were determined in vitro and in vivo. Net protein ratio (= 2.65) and true digestibility (= 80.3) were compared with gelatin and caseinate. Protein digestibility was determined by pH-stat method and cell dialysis. Amino acid composition including 4-hydroxyproline, allowed determination of connective tissue, amino acid score and protein digestibility corrected amino acid score. High correlation was found between true digestibility and pH-stat method (R²= 0.99). Meaty flavor and gelling properties of veal hydrolysate could make it useful for high-quality soups, sauces and gravies.     

Coalescence Index of Protein-Stabilized Emulsions

A simple method is proposed to estimate coalescence stability of protein-stabilized emulsions. Coalescence was accelerated through agitation and measured by change in emulsion turbidity over time. A coalescence index (CI) was determined and used to compare emulsions stabilized with casein, whey (WPI) and soy protein isolates (SPI). CI increased when stirring rate increased. Casein produced more stable emulsions, followed by WPI and SPI. High homogenization pressure increased coalescence stability of WPI and SPI-stabilized emulsions and decreased coalescence stability of casein-stabilized emulsions. Microscopic examination, showed agitation of the emulsion had clearly induced formation of large oil droplets which acted as coalescence nuclei.     

High temperature compression creep of aluminium nitride after immersion in molten stainless steel

The effect of immersion in molten steel on subsequent creep behaviour has been investigated in two AlN ceramics. Steady-state creep was not significantly affected but an enhanced initial creep rate was observed, especially when the surface layer had not been removed after immersion. In immersed samples, SEM revealed some open porosity and microcracks near the surface and particles containing steel constituents were found by TEM deep inside samples, in grain-boundary secondary phases. This revised version was published online in November 2006 with corrections to the Cover Date.