77 research outputs found
Determination of added mass for earthquake induced hydrodynamic loadings on vertical structures
No full textEarthquakes can induce severe hydrodynamic loadings on dams and their equipment. The dynamic dam-reservoir interaction is usually modelled by the so-called added mass. There are two theoretical approaches in the literature, employing either momentum or compressibility theory. Both assume zero pressures at the top of the structure, leading to comparatively low design pressures for control structures. A new theory was developed for a simple approximation for added mass and hydrodynamic pressures. The added mass is assumed to be uniform over the dam height. The added mass becomes a linear function of acceleration and water depth. Comparison with 'classic' theories showed good agreement for accelerations up to 0.3g, and higher pressures for higher accelerations
Hydropower converters with head differences below 2·5 m
Get PDFHydropower with very low head (VLH) differences constitutes a largely unused potential source of renewable energy. A literature review of hydropower converters for VLH differences covering the engineering literature from the 1830s onwards was conducted to assess the potential of historic, current and emerging technologies. The results showed that a large number of different interesting technologies were used/developed, and that several novel and promising concepts are currently under development. Technologies emerged for different market segments: water wheels for low flow rates, turbines for large flow volumes. To take account of increased ecological demands and the desire for cost reduction, further improvements of existing technologies and new converter technologies have been developed. Other concepts described in the literature were apparently never applied although they promise development potential. The information gathered allowed for a comparison of available technologies with respect to area of application, performance, ecological impact and cost level
Design of steel lined penstock of hydroelectric power plant
Get PDFDie Diplomarbeit "Variantenuntersuchung der Druckrohrleitung eines Speicherkraftwerkes an einem Stausee" untersucht das Konzept, die Varianten und die Konstruktion der Anlagen eienes geplannten Speicherkraftwerkes. Die vorgegebene Plannungsunterlage umfaßt gleichzeitig viele Lösungskonzepte. Die entsprechenden Anlagen über die ganze Trasse der Druckrohrleitung sind einen vertikalen Druckschacht, eine gepanzerte unterirdische Hochdruckstrecke und eine eingeerdete Druckrohrleitung. Die drei Anlagen wurden hydraulisch und statisch bemisst. Die hydraulische Bemessung wurde für die stationären und instationären Vorgänge durchgeführt, wobei die Untersuchung der stationären Zustände die Ermittlung der kontinuierlichen Verluste in der Druckrohrleitung infolge der Flüssigkeitsreibung (Wandreibungsverluste) und der örtlichen Widerstände wie z.B. Rohrverengungen oder - erweiterungen erfasst. Bei den instationären Strömungsvorgängen wurde die maximale Erhöhung des statischen Druckes infolge einer Druckstoßentwicklung untersucht. Die instationäre Berechnung wurde mit dem an der UACG erarbeitetes Berechnungsprogramm "HIUD" nach der Charakteristickenverfahren durchgeführt. Als Egebnis liefert das Programm die Werte von der Druckhöhe, Geschwindigkeit und dem Durchfluß in jedem Berechnungspunkt für jeden Zeitschritt. Diese Änderungen der drei Parameter für den konkreten Fall wurden tabelarisch und grafisch dargestellt.Danach wurde die statische Bemessung durchgeführt. Aufgrund der Berechnungsergebnisse wurden die notwendigen Stützkonstruktionen und Auskleidungen des vertikalen Druckschachtes und der geneigten gepanzerten Strecke bestimmt.Für den Druckstollen mit der gepanzerten Auskleidung wurde zusätzlich noch eine Beulberechnung durchgeführt. Zu diesem Ziel wurden die Berechnungsmethoden von Amstutz, Montel und Jacobsen verwendet und die entsprechenden Ergebnisse verglichen.Die statische Bemessung für die letzte eingegrabene Strecke von der Triebwasserleitung wurde nach den bulgarischen Normen und nach ÖNORM B5012 durchgeführt und einen Vergleich zwischen den Ergebnissen und den Grundlagen der beiden Standards gemacht.Im letzten Kapitel wurde eine Beschreibung der Bauverfahrenstechnik der Anlagen gemacht. Es wurden die verschiedenen Ausbruchsmethoden, die Felssicherungsarten, die notwendigen Baumaschinen und Baugeräte mit den einzelnen Arbeitsvorgänge dargestellt
Pumped-storage in Bulgaria – Developments, Current Situation and Some Perspectives
No full textAbstractThe objective approach requires that the hydropower development cannot be analyzed outside the economical and overall national development of a particular country during a considered time period. Yet the current presentation addresses exclusively the Hydropower development in Bulgaria, and moreover, concentrated only on the features of pumped-storage as a reliable and still highly competitive energy storage technology.The pumped-storage as part of the hydropower development in Bulgaria and the situation as in 1989 are introduced. The overall development in Bulgaria after November 1989 and its impact on both running and future hydropower and pumped-storage projects are shortly presented. Particular features of the current situation are outlined. Furthermore, special attention is paid to the national legislative environment in the frame of the crucial policies, strategies and directives of the European Union.Finally, some ideas and project possibilities for the use of the still available pumped-storage potential in Bulgaria are discussed in more detail. The work ends with conclusions on the Bulgarian hydropower development with respect of pumped-storage mainly after 1989. Needed research activities in particular fields are identified for a possible future pumped-storage development in Bulgaria as an EU member state in the sense of global electricity market conditions
Is unitary and integral Yugoslavia possible?
No full textTitle: Bъзмοжнa πu e euòннa u uяπocmнa Юƨocπaeuя? Ha ƨpaнuyama мeжòy noπumuκama u фuπocoфuяma (Is unitary and integral Yugoslavia possible? On the borderline between politics and philosophy) Originally published: in the magazine Фuπocoфcκu npeƨπeò, IV, 1932, vol. III, pp. 197–227. Language: BulgarianThe excerpts used are from the original, pp. 213–214, 220, 221–223. About the author Dimitar Mihalchev [1880, Lozengrad (Tur. Kirklareli, present-day Turkey) – 1967, Sofia]: philosopher and diplom..
THE IDIOLECT OF REVEREND ECONOMOS DIMITAR POPNIKOLOV PETKANOV
Get PDFA less studied talented author and brother of the popular fiction writer Konstantin Petkanov, priest
Dimitar wrote in the 1950s. This publication analyzes several parameters of his idiolect: phonetic peculiarities (reflex of ѣ, ѫ,
ъ; epenthetic [l]; reflexes of the [tʃ] [dʒ] groups; phonetic dialectisms; phonetic doublets); morphological paradigm (case
inflections; noun form for number; dualis; nomina collectiva; extended Church Slavonic suffix for adjectives; dialectal and
contracted pronoun forms; a temporal system characterized by high frequency of the verbs in terms of origin, distribution and
stylistic differentiation); lexical specifics (in terms of origin, distribution and stylistic differentiation). Emphasis is placed on
those lexical layers that constitute and ditinguish the author’s language. Hapaxes (produced using morphological and non-
morphological methods), rare words, semantic transponents, dialectisms, colloquial vocabulary and foreign words are studied.
All linguistic phenomena are examined retrospectively and in comparison with the synchronous linguistic situation before and
after the orthographic reform of 1945 in order to highlight the innovative contribution and the mechanisms through which the
author enriched the contemporary Bulgarian vocabulary. Occasionalisms, dialectal and archaic units occur more often in
Petkanov’s poetic works than in his fiction. The source material has been excerpted from Volume 1 (January – March) and
Volume 2 (April – June) of the hagiographic tetralogy “The Year of Our Lord“ and the memoir “A Book about My Brother –
the Writer Konstantin N. Petkanov“, which were published a few years ago by Dimitar Petkanov’s heirs
Imperium Militiae(I)
No full textThe most common idea in Romance studies is that Romans, as practical people, didn’t conduct theoretical research on their country or their army, but they gradually built them both. Meanwhile, they reformed and upgraded it, so that they could respond to the challenges of their age. Moreover, the basis of their research was not explicit doctrines, or prior concepts, in fact they used their own, or the experience of others, to find concrete solutions to daily problems. Just as the Hellenic romanophile Polibius (200-120 B.C), in his work Historia, asks the crucial question: ”Is it possible to have such an unreliable man who is not interested in how the Romans, with their unicipal structure, managed to conquer the whole world”? - in the same way the author of this paper, as much as its content allows, humbly and unpretentiously tries to answer the crucial question: “What kind of military structure
created and defended one of the biggest and most enduring empires in world’s history, and what rules governed it”
Earthquake-induced vibrations of a buried pipeline including fluid-structure interaction � numerical solution
No full textNichtlineare dynamische Untersuchung einer 70 Jahre alten Gewichtsstaumauer in Bulgarien
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