Der Turbogenerator mit supraleitender Erregerwicklung im transienten Betrieb

Übersicht Die weitgehende Verwendung nichtmagnetischer Werkstoffe beim Bau von Turbogeneratoren mit supraleitender Erregerwicklung erfordert die Erarbeitung neuer theoretischer Grundlagen zur Vorausberechnung des Betriebsverhaltens. Mit Hilfe der Raumzeigerdarstellung wird ein den dynamischen Betrieb beschreibendes Differentialgleichungssystem für ein vereinfachtes mathematisches Modell der Maschine abgeleitet.

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Contents The prevalent application of nonmagnetic materials in construction of turbine generators with superconducting field windings demands the development of new theoretical fundamentals for the predetermination of the operational behaviour. Using the definition of space vectors, for a simplified mathematical model of a generator a set of differential equations is presented, suitable for the calculation of transient performance.

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Verzeichnis der verwendeten Symbole a Augenblickswert des Strombelags - g ganze Zahl - i Augenblickswert des Stromes - j imaginäre Einheit - J polares Massenträgheitsmoment - l Länge des geraden Wicklungsteils - L Eigeninduktivität - m Augenblicksert des Drehmoments - M Kopplungsinduktivität - P Grundwellenpolpaarzahl - r radiale Koordinate, Radius - R ohmscher Widerstand - u Augenblickswert der Spannung - v Augenblickswert des Vektorpotentials - W _Spl Spulenweite, bezogen auf den mittleren Radius der Ständerwicklung - z axiale Koordinate - Z in Reihe geschaltete Leiter, Stabzahl der Käfigwicklung - räumlicher Winkel - Bogenkoordinate - ₀ magnetische Feldkonstante - natürliche Zahl - Ordnungszahl - v₁ vorzeichenbehaftete Ordnungszahl - natürliche Zahl - Wicklungsfaktor im geraden Wicklungsteil - _p1 Polteilung, bezogen auf den mittleren Radius der Ständerwicklung - Augenblickswert des magnetischen Flusses - Augenblickswert der magnetischen Flußverkettung - 1 Ständerwicklung - 2 Erregerwicklung - 3 Dämpferwicklung - a außen - A Strang A - b Belastung - B Strang B - C Strang C - d Längsachse - i innen - J Joch - m mechanisch - o Oberschicht, oben - q Querachse - s Strombelag - St Stab - u Unterschicht, unten - natürliche Zahl - Ordnungszahl - v₁ vorzeichenbehfaftete Ordnungszahl - natürlich Zahl Der Verfasser dankt Herrn Prof. Dr.-Ing. H. W. Lorenzen, Lehrstuhl und Laboratorium für Elektrische Maschinen und Geräte, TU München, für die Anregung und Förderung, dieser Arbeit. Sie dient als Voruntersuchung zum Thema Elektrische Grenzleistungssynchrongeneratoren mit supraleitender Erregerwicklung im Rahmen des Schwerpunktprogramms Neue Elektrische Antriebe der Deutschen Forschungsgemeinschaft, Bad Godesberg.     

Impedance and elektrodynamic force acting on a cylindrical conductor partly filling a semi-closed slot

Contents In this paper the inner impedance and the electrodynamic force acting on a cylindrical conductor partly filling a semi-closed slot are calculated. The investigations are made by using the separation of variables method.

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Übersicht Es werden die innere Impedanz und die elektrodynamische Kraft, die auf einen kreisförmigen Leiter wirkt, der eine halbgeschlossene Nut partiell ausfüllt, berechnet. Zur Berechnung wird die Methode der Trennung der Variablen angewendet. Die Ergebnisse sind in Kurvenform dargestellt.

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Symbole A z-component of the vector potential (complex r.m.s. value) - B _x, B_y components of the magnetic induction (complex r.m.s. value) - F electrodynamic forece - I current (r.m.s. value) - I _n(z) modified Bessel function of first kind - imaginary unit - J z-component of the current density (complex r.m.s. value) - L(o) inductance for direct current - R resistance - X reactance - Z impedance - z ^* conjugate complex number ofz - Rez, Imz, |z| real part, imaginary part and modulus of complex numberz - ₀ magnetic permeability - pulsation - Kronecker symbol - 1 atn=m o otherwise     

Two-dimensional analysis of linear induction motor using Fourier's series method

Contents A single sided linear induction motor with finite length of the primary is considered. Calculations of magnetic flux density, secondary current, forces and power losses in two layers of a secondary are based on Fourier's series method. Variation of magnetic flux density across an air-gap and finite values of permeability and conductivity of the secondary back iron were taken into account in the computational model. Calculations were compared with test results.

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Zweidimensionale Analyse des linearen Induktionsmotors nach der Methode harmonischer Fourierreihen

Übersicht Es wird ein einseitiger linearer Induktionsmotor bei Berücksichtigung endlicher Strombelaglänge betrachtet. magnetische Induktion, Strom-, Kraft-und Verlustdichte in zwei Schichten des Sekundärteiles wurden auf Grund der Methode harmonischer Fourierreihen berechnet. Im rechnerischen Modell wurde die Änderung der magnetischen Induktion im Spalt und der endliche Wert der magnetischen Induktion im Spalt und der endliche Wert der magnetischen Permeabilität sowie der Leitfähigkeit von Eisen im Sekundärteil berücksichtigt. Die Berechnungen wurden mit Ergebnissen experimenteller Untersuchungen verglichen.

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List of symbols and abbreviations a primary width - B magnetic flux density - b slot opening - c secondary width - d conducting plate thickness - E electric field intensity - F force - f force density - H magnetic field intensity - J current density - J ^s primary linear current density - J ^r secondary linear current density - K _t finite primary width correction factor - K _b Carter's coefficient - k, u, i harmonic and wave number - L primary length - q number of slots per pole per phase - s slip - v secondary speed relative to primary - v _ijk speed of the kui field harmonic - w _s number of wires per slot - P _e secondary power losses - p _e secondary power loss density - modified air-gap length - _a actual air-gap length - permeability - modified air-gap length - permeability - modified secondary conductivity - _a actual secondary conductivity - [ _s –L] distance between adjacent primaries - _t tooth pitch - _z pole pitch - Q - Q* conjugate value ofQ     

Lessons learned from the testing of RC frames with masonry infills and proposals for new solutions / Untersuchungen an mit Mauerwerk ausgefachten Stahlbetonrahmen und neue Lösungsvorschläge

Past experience has shown that inadequate design of unreinforced masonry walls (URM) or inadequate selection of materials can lead to significant economic losses and fatalities in the case of a strong earthquake. In this context, this paper presents the experimental research that has been carried out with the aim of gaining a better insight into the traditional masonry infill walls commonly built in Portugal. The experimental research includes: (1) shaking table tests on reduced‐scale reinforced concrete (RC) buildings with masonry infills with distinct typologies, from traditional solutions to those with enhanced properties and solutions to improve the seismic behaviour; (2) in‐plane static cyclic tests on a representative one‐storey, one‐bay RC frame with masonry infills with distinct typologies but similar to the ones tested in the RC building models. It was concluded that the typology of masonry walls influences the global behaviour of RC buildings, particularly when there is no connection between masonry infill and RC frame. An appropriate design is necessary to prevent an unforeseen failure mechanism due to shear stresses in the RC columns induced by the infill. The in‐plane cyclic tests showed that render plays a central role in the lateral strength and stiffness. Additionally, it was observed that bed joint reinforcement and reinforced render are important measures for controlling damage but do not significantly influence the in‐plane lateral strength and stiffness.     

Verification of sound insulation in residential building – the new DIN 4109 / Nachweis des Schallschutzes im Wohnungsbau – die neue DIN 4109

The central sound insulation standard for building in Germany, DIN 4109, was issued in a revised version in July 2016. The calculation procedures described in the standard can now be used to verify constructional sound insulation for masonry buildings with insulated external walls. For other building materials and construction methods, the minimum requirements can be verified, or if required the enhanced requirements. Measurements in completed buildings confirm the results and show that provided the construction materials are suitable and the specialist design is correct, good sound protection is regularly achieved.     

Bracing systems in masonry buildings / Aussteifungssysteme im Mauerwerksbau

In this article, an FE analysis model suitable in engineering practice for masonry bracing walls acting as deep beams without tensile strength is compared with simple models based on trusses. The results of both processes are compared through the example of a four‐storey building of Poroton masonry.     

Reinforced masonry beams under shear load – Proposals for future designs / Bewehrte schubbeanspruchte Mauerwerksbalken – Vorschläge für zukünftige Bemessungen

This article is written against the backdrop of the work of the European standardisation committees on the amendment of EN 1996‐1‐1 [N 4] which will also exert an influence on the design of reinforced masonry in Germany. This paper focusses on the design approaches of DIN EN 1996‐1‐1 for untensioned reinforced masonry beams under shear load in the ultimate limit state (ULS). Proposals are made to discuss their revision. The contents of E DIN 1053‐3 [N 3] and of the final draft of the guideline ”Flat Lintels” [7] are taken into account.     

Public policy challenges and implications of the Internet and the emerging e-commerce for sub-Saharan Africa: A business perspective

As businesses move to establish closer links with their customers and suppliers in the global marketplace, a new set of requirements is being placed on businesses in sub-Saharan Africa. The rules of commerce are being turned upside down, and for sub-Saharan African businesses to compete, local governments would have to create an enabling Internet and information infrastructure. This paper examines the Internet environment in sub-Saharan Africa and explores what the Internet can do for businesses. It investigates the public policy challenges and implications of the Internet and the emerging e-commerce for sub-Saharan Africa. The paper ends with a discussion and conclusion.     

Probleme bei Planung und Betrieb von Absetzbecken für Straßenabwässer

Sedimentation basins are incorporated into runoff infiltration systems and serve as a retention system, in which the sedimentation of particles occurs as a result of gravitational force. The effectiveness of sedimentation basins in terms of removing particles is highly dependent on design parameters such as their dimensions and drainage times. To evaluate the flow distribution within sedimentation basins, a conceptual model was developed using a tracer and compared to the actual condition at the treatment system. Here, a significant difference in the height of the connecting tube between settling basin and filter basin was found. This leads to a drying out of the basin, which significantly affects the flow rates and hence the sedimentation there. Based on a model experiment with colour tracer, the flow paths were visually represented in the basin, and both the concrete variant and the effects of internal structures were considered. It was found that the incorporation of a baffle led to an improved utilization of the basin, and to water being retained for longer times. Due to the lower flow rate and these longer times, fine and medium-sized sediments could be easily settled. In a field study, the performance of a sedimentation basin for the removal of particles was evaluated based on the influent and effluent concentrations of total suspended solids (TSS). The street runoff treatment plant was monitored for one year and results showed that there was no particle accumulation in the sedimentation basin (there was no permanent retention of the particle loads). The mean TSS concentrations were 89 mg/L at the inlet of the sedimentation basin and 94 mg/L at the end of the settling tank, respectively. The structural design and operation of the system showed higher flow and turbulent flow conditions in the sedimentation basin, in which settlement of fine and medium sized particles was very low; as a result, the soil filter basin was loaded with runoff particles. Thus the particulate matter had to be removed either on the surface of the filter basin or within the porous space of the filter. The build-up of such particles can result in a significant increase of head loss due to clogging; therefore, filters must be maintained by removing the accumulated particles on a regular basis.     

Covariant-Conics Decomposition of Quartics for 2D Shape Recognition and Alignment

This paper outlines a new geometric parameterization of 2D curves where parameterization is in terms of geometric invariants and parameters that determine intrinsic coordinate systems. This new approach handles two fundamental problems: single-computation alignment, and recognition of 2D shapes under Euclidean or affine transformations. The approach is model-based: every shape is first fitted by a quartic represented by a fourth degree 2D polynomial. Based on the decomposition of this equation into three covariant conics, we are able, in both the Euclidean and the affine cases, to define a unique intrinsic coordinate system for non-singular bounded quartics that incorporates usable alignment information contained in the polynomial representation, a complete set of geometric invariants, and thus an associated canonical form for a quartic. This representation permits shape recognition based on 11 Euclidean invariants, or 8 affine invariants. This is illustrated in experiments with real data sets.