Search results

In the paper a comparison between the analytical and numerical method of no‐load computation will be made taking into account the initial hypothesis and computational effort face to the concrete obtainable results. It is concluded that the reduced fixed‐mesh FEM analysis of the induction motors is very suitable for no‐load computation because it relates directly to the well known equivalent circuit parameters. The symmetry of the machine allows for the computation only on a small part of the magnetic circuit so that the time of computation can be reduced even when a relatively fine mesh is used. However, for the optimal design of the motor it appears that analytical methods are very suitable owing to the simplicity and accuracy of the design.

C'est avec une certaine joie et une satisfaction toute particulière que je vous souhaite la bienvenue à ce 36e Congrès qui se tient dans mon pays natal, pays qui est en même temps le siège de notre association. Ce dernier fait n'est pas un hasard puisque c'est précisément à Lugano qu'en 1959, à l'invitation des prof. Hunziker et Krapf, différents scientifiques du tourisme se sont retrouvés afin de promouvoir la recherche touristique d'après‐guerre. Depuis que notre association existe — et l'indication “36e Congrès” précise également l'âge de l'AIEST — nous nous sommes déjà rencontrés en Suisse, en 1958 et en 1960 et je me souviens qu'en 1960 déjà nous avons eu l'occasion d'apprécier la gastronomie du Château de Chillon, ou aura lieu notre banquet de clôture.

Now that we have reviewed the basic reports, the published special reports and the discussions of the working groups let us see what can be high‐lighted as a conclusion. How has this Congress advanced the science of tourism applied to mega‐attractions and to mega‐events?

Excellenzen meine sehr verehrten Damen und Herren liebe Kollegen Es ist mir eine besondere Freude und Ehre, erstmals einen AIEST Kongress in der Sozialistischen Republik der Tschechoslowakei zu eröffnen und dies in der prächtigen Stadt Prag, der Hauptstadt und dem kulturellen und politischen Mittelpunkt. Die Stadt ist durch ihr reiches Erbe an kulturellen Gütern besonders für unsern 34. Kongress geeignet. Auf den berechtigten Wunsch der Organisatoren des diesjährigen Kongresses hin haben wir das Thema “Tourismus und architektonisches Erbe — kulturelle, rechtliche, wirtschaftliche und marketing‐orientierte Aspekte” gewählt.

This paper aims to establish a modified variable coefficient calculation model to analyse the control parameter effect on the iron loss of switched reluctance motor under pulse width modulation (PWM) mode.

The finite element model is solved to get the flux density by python language. Due to non-sinusoidal flux density feature and the effect of PWM excitation, the Fourier transform is applied in consideration of harmonic components. To improve the accuracy of iron loss computation, the effect of minor loops is considered by using the rain-flow counting method.

When the speed fluctuates around the set speed and the fluctuations are relatively small, it is useful to reduce the iron loss with smaller duty ratio and turn-on angle or greater duty ratio and smaller turn-off angle. The iron loss is less affected by chopping frequency, while the iron loss increases obviously with higher conduction angles. The iron loss under non-energy-returnable-voltage-chop mode is greater than energy-returnable-voltage-chop mode.

The modified variable coefficient MIEM5 iron loss model is proposed to improve the accuracy of iron loss calculation. Then the control parameters such as duty ratio, chopping frequency, turn on angle and turn off angle are analysed under PWM mode.

In der aktuellen Diskussion ber den Fremdenverkehr allgemein und die Fremdenverkehrspolitik im besonderen stehen zur Zeit — insbesondere im Alpenraum — Umweltaspekte im Vordergrund 1). Dies rechtfertigt zweifellos das Adjektiv ‘umweltorientiert’ im Zusammenhang mit der Fremdenverkehrspolitik. Dennoch soll hier zunächst eher all‐gemein auf die Fremdenverkehrspolitik und ihre wirtschaftlichen Ziele eingegangen werden; letztlich wird sich herausstellen, dass zwar jede Fremdenverkehrspolitik auf Umweltbelange Bedacht nehmen muss, wenn sie Nachfrage anziehen und damit ihrem Anspruch auf Erreichung bestimmter regionaler Wirtschaftsziele gerecht werden will, dass aber vor allem in der Frage der touristischen Landschaft Zielkonflikte zwischen der Erreichung wirtschaftspolitischer Ziele und Umweltfragen auftreten können.

The purpose of this paper is to focus on the structural integrity of the rainwater propeller pumps installed in the municipal wastewater treatment plant (WTP).

A numerical analysis is performed to determine the maximum shear stress on the fasten bolts. The rainwater propeller pump is examined in operation at normal conditions and when one blade is progressively blocked.

The failure mechanism of the rainwater pump impeller is determined.

The fibbers and wastes are discharged together with rainwater during storms with these types of pumps to avoid the flood of the WTP. Several catastrophic events have occurred in service due to the fibbers clog the gap between the impeller blades and the pump casing. The clogging process is partially understood so actual technical solutions deal with effects rather the main causes.

The operation time of all seven rainwater pumps installed in Timisoara’s WTP is investigated. Climate changes in Banat region and new waste properties found in the wastewater require appropriate technical solutions. A technical solution is proposed based on these investigations to extend the operation time and to diminish the operation and maintenance costs.

These large pumps are installed in the urban sewage centralised system implemented in the most cities. The access to the sewerage network is a requirement of any community, regardless of the social status.

The fracture surfaces of both fastening bolts of the rainwater pump impellers produced in service are examined. As a result, it has been identified that the catastrophic events are due to the brittle fracture of both fasten bolts between the impeller blades and the pump hub, respectively. The catastrophic events of the rainwater propeller pumps are directly correlated to the clog level of the impeller. The numerical simulation is performed to determine the maximum shear stress on the fasten bolts. The case with pump operating at normal conditions is performed identifying its vulnerabilities to clog conditions. Next, one impeller blade is progressively blocked considering three time stop scenarios associated with different clog levels. Conclusively, the operating time of the rainwater pump up to the catastrophic failure is correlated to the clog level of the impeller.