3,579 research outputs found
A direct A.C. to A.C. regenerative frequency and voltage converter
No full textIncludes bibliographical references.The reliable variable speed operation of an a. c. machine over a wide speed range is a problem that has received attention for some time. In this thesis a system to permit such operation from a fixed frequency fixed voltage supply is proposed, under the name of the asynchronous modulation converter. This converter is of the cycloconverter family, but is force-commutated and is not synchronised with the supply frequency. The power switching element comprises a power transistor in a diode bridge, coupled to the control circuitry by opto-isolators. The output of the a-mod converter is produced by a "chopper" modulation process and this results in the harmonics present being at frequencies well removed from the fundamental. A feedback system to ensure smooth commutation of the output current from the power switches is described. This feedback system operates by sensing the rate of rise of the inductive voltage surge on the load when a switch is opened to operate a freewheel path switch
Cratere stamnoide da Monte Bibele
No full textScheda di reperto ceramico: cratere decorato di fine IV-inizi III sec. a.C., di ambito produttivo incerto, forse imitazioni locali (padane) influenzate da produzioni tirreniche e dell'Italia meridionale
Lo scontro tra Eracle e il 'brigante' Cicno: riletture magno-greche di un mito tra VI e V-IV secolo a.C. da Stesicoro a Pindaro (e a Dionisio I)
No full textLa conflittualità confinaria tra Rhegion e Lokroi Epizephyrioi, documentata a partire dal V secolo a.C., sembra risalire già al pieno VI secolo a.C. stando ad un frammento stesicoreo (forse pertinente al Cicno) poi ripreso in chiave propagandistica dal tiranno siracusano Dionisio I
Nuovi dati dagli scavi nell'area a nord del Santuario nella seconda metà del VI sec. a.C.
No full textI nuovi scavi hanno portato alla luce un settore insediativo organizzato lungo un asse stradale ortogonale alla grande arteria Caere-Pyrgi, comprendente edifici di planimetrie diverse. Il più articolato è un edificio porticato fiancheggiante il lato sud della strada, con copertura di terrecotte architettoniche dipinte di tipo ceretano databili nel 530/520 a.C. Rinvenute inoltre sul terreno interventi di carattere votivo, legati forse a fasi di dismissione e rifacimento, e un altare con basamento in lastroni di pietre
Zane Grey with Orange A.C. baseball team
No full textThis photograph shows Ohio native Zane Grey with the Orange A.C. Baseball Team, ca. 1896-1904. Prior to becoming a well-known author of western novels, Zane Grey was also a dentist and a semi-professional baseball player, with teams including the Orange Athletic Club and the Newark (New Jersey) Colts
Trasformazioni del paesaggio nel territorio di Segesta tra VII e II secolo a.C.
No full text2012 - 2013The aim of this research is to analyze the settlemet dynamics in the territory of CalatafimiSegesta (TP) between the seventh and the second century BC. The scientific background
consists of the data collected during the surveys conducted in 1995-1997 by the University
of Siena. The oldest archaeological traces of a cult space planning, and perhaps even the
living space, on Mount Barbaro, dating back to the last quarter of the seventh century BC.
During the Hellenistic period, we can see a major transformation of the landscape of
Segesta, with a stable population of the countryside. At the end of the second century BC
is evident a change in the large urban restructuring of Segesta and in the monumental
forms of worship in the surrounding areas, expressions of political power and wealth of the
local ruling class. [edited by Author]La ricerca propone un’analisi delle dinamiche di popolamento che hanno caratterizzato la
parte di territorio compresa all’interno dei confini comunali di Calatafimi-Segesta tra il VII
ed il II secolo a.C., attraverso una revisione critica dei dati del survey condotto
dall'Università di Siena negli anni 1995-1997, finalizzato alla redazione di una Carta
archeologica del Comune.
La scelta del termine cronologico più antico è dovuta al fatto che le prime tracce materiali
di una pianificazione dello spazio cultuale, e forse anche abitativo, sul Monte Barbaro,
sede in età classica dell'abitato indigeno di Segesta, risalgono all'ultimo quarto del VII
secolo a.C.
Nel corso dell'età ellenistica si assiste ad una profonda trasformazione del paesaggio
segestano, con la fitta occupazione stabile delle campagne. Alla fine del II secolo a.C. una
netta cesura è evidente nella complessa ristrutturazione urbanistica della città di Segesta
e nelle forme monumentali di alcune aree cultuali nel territorio circostante, espressioni del
potere politico e della ricchezza della classe dirigente locale. [a cura dell'Autore]XII n.s
Experimental research on spatial distribution of overtopping
No full textThe overtopping empirical formulas calculate the discharge only at the top of the crest of a coastal protection structure. On the other hand, the tolerable overtopping discharges are defined at certain points behind the crest where the total overtopping is reduced. The scope of this thesis is to find an empirical formula to describe the distribution of overtopping at the space behind the crest. This thesis comes as a further investigation on the work conducted by v.Kester [2009] for regular waves. In this research, a physical model was developed on which irregular waves are tested. Because of the duration of the tests and the amount of collected water (significant lose of water during the test), a completely new measuring system was designed. Five influencing parameters (variables) are considered on this research: wave height, wave period/steepness, slope angle, crest freeboard and crest permeability. The entire overtopping process is analysed separately for the total overtopping discharge, the overtopping discharge directly behind the crest and the distribution of overtopping behind the structure. In the analysis of the data collected from the measurements, the impact of the varying parameters is investigated leading to useful conclusions and better understanding of the entire process. Additionally, the experimental findings are analysed and compared to the relative existing methods. Based on the TAW [2002] method which is proposed by the EurOtop Manual [2007], a prediction formula is developed. This formula is a generic version of TAW [2002] formula in which a new reduction factor ?c is introduced in order to describe the decay of the overtopping and thus predict the discharge at any certain distance behind the crest. Other relevant methods are also analysed (Juul Jensen [1984], Steenaard [2002], Besley [1999] and v.Kester [2009]) and conclusions for their applicability are drawn leading to suggested improvements or corrections. Apart from the distribution of overtopping, on this thesis the determination of crest freeboard (which is an ambiguous issue) is also investigated. Finally, suggestions of further research on this topic are discussed. The entire work has been perfomed in close cooperation with van Oord.Hydraulic EngineeringCivil Engineering and Geoscience
P.Würzb. II 25. Frammento di documento ufficiale (?)
No full textEditio princeps di un frammento di documento, forse ufficiale, dalla Tebaide; II sec. a.C
Flow over partially liquid filled cavity
No full textExperiments have been carried out to investigate the effect of liquid cavity filling on the behavior of the gas flow over a flat plate cavity. PIV measurements in the gas phase reveal that cavity filling can affect vortex shedding in the cavity mouth. Shear layer vortices can break-up into smaller vortices, thereby losing their periodic interaction with the aft wall and, hence, their sound producing potential. Expected is that this is one of the mechanisms causing sound mitigation in corrugated pipes with liquid addition, observed in literature
On modular lattices generated by chains
No full textDe La Maza, A.C. (reprint author). Instituto de Matematica y Fisica, Universidad de Talca. Casilla 747, Talca, Chile.We describe the free modular lattice generated by two chains and a single point, under the assumption that there are few meets
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