Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vi, 21, [24] p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 20-21).

Popularly used impedance-based methods need voltage and current waveform as well as line impedance per unit length to estimate distance to fault location. For a non-homogenous system with different line configuration, these methods assume that the system is homogenous and use the line impedance of the most frequently occurring line configuration. Load present in the system before fault is an important parameter which affects fault location accuracy. Impedance-based methods like Takagi and positive-sequence method assume that the load is lumped beyond the fault point which may not be true for a typical distribution system. As a result, accuracy of the impedance-based methods in estimating distance to fault is affected. Another short-coming of impedance-based methods are that they are unable to identify the branch in which the fault may be located. To minimize these errors, this thesis proposes a short-circuit fault current profile approach to complement impedance-based algorithms. In the short-circuit fault current profile approach, circuit model of the distribution feeder is used to place faults at every bus and the corresponding short-circuit fault current is plotted against reactance or distance to fault. When a fault occurs in the distribution feeder, fault current recorded by relay is extrapolated on the current profile to get location estimates. Since the circuit model is directly used in building the current profile, this approach takes into account load and non-uniform line impedance. Using the estimates from short-circuit fault current profile approach and impedance-based methods, the path on which the fault is located is identified. Next to improve fault location estimates, a median value of the estimates is computed. The median is a more robust estimate since it is not affected by outliers. The strategy developed above is tested using modified IEEE 34 Node Test Feeder and validated against field data provided by utilities. For the IEEE 34 Node Test Feeder, it is observed that the median estimate computed from impedance-based methods and the short-circuit fault current profile approach is very close to the actual fault location. Error in estimation is within 0.58 miles. It was also observed that if a 0.6 mile radius is built around the median estimate, the fault will lie within that range. Now the IEEE 34 Node Test Feeder represents a typical distribution feeder and has also been modeled to represent the worst case scenario, i.e. load current is around 51% of the fault current for the farthest bus. Hence the 0.6 mile radius around the median estimate will hold true for most distribution feeders and will be used when computing the fault range for field case events. For the field events, it was seen that the actual faults indeed lie within the 0.6 mile radius built around the median estimate and the path of the fault location has also been accurately estimated. For certain events, voltage waveform was not useful for analysis. In such situations, short-circuit fault current profile alone could be used to estimate fault location. Error in estimation is within 0.1 miles, provided the circuit model closely represents the distribution feeder. / text

This study uses a 1375 km2 3D seismic dataset located in the late Miocene to Pliocene Mississippi River Delta in order to investigate the external characteristics, lithology, and evolution of channelized deposits within the seismic survey. Fluvial thicknesses range from about 11 m to 90 m and widths range from about 100 m to 31 km. Channel fill can be generalized as sandy with low impedance and high porosity (~ 35%), though heterogeneity can be high. Three distinct fluvial styles were recognized: incised valleys, channel-belts, and distributive channel networks. Fluvial styles were interpreted as a result of changes in sea-level and a speculative late Miocene to Pliocene Mississippi River Delta sea-level curve constructed using these relationships. Additionally, a characteristic interval between the major changes in fluvial style was found. These fluvial systems interact with and are affected by other elements in the landscape. Growth faults in particular are common within the survey area; however, the dynamic between fluvial systems and growth fault related subsidence has been poorly understood and so was also a focus of this project. Previous work as well as this study found little evidence that growth faults are able to affect the course or geometry of the majority of small (with most < 500 m in width and < 20 m in depth) channels. However, the relationship between growth faults and larger scale channel-belt systems (between 1 km and 5 km in width and > 25 m in depth) has not been previously evaluated in this area. In contrast to the majority of small distributary channels found within the survey, channel-belts appear to be steered by growth faults. Fluvial response or insensitivity to fault induced subsidence is related to the relative timescales of avulsion and faulting. Channel-belts are longer lived features than more ephemeral small distributary channels. Channel-belts, due to their relatively low mobility compared to small channels, are more likely to experience punctuated faulting events which results in greater apparent sensitivity to faulting than seen in small channels. / text

A study f the characters of the Tertiary dyke-swarms of Skye, Ardnmurchan and. the Small Isles of Invernessshire is based on observations at over 7500 dyke-outcrops, most of whiciL are located along well-exposed traverses. Because of geological limitations analyses of the properties of the dykes (trend, dip and thickness) can be semi-statistical only. Each of the dyke-swarms consists of a regional linear component of LW. to N.N.W. trending dykes, including parallel secondary-swarms in Skye and Ardnamurchan, together with in Skye and R.hum N.E. subswarnis of distinctive geo-. graphic distribution and comparatively- low intensities. The observations taken have facilitated: (a.) the construction of contour-maps depicting symmetrical distributions of multiple- dykes, of the arithmetic-average trends and thicknesses of the dykes, etc., (b.) both an approximate delimitation of regional-swarms and the distinction of these from subsidiary-avarms, in each case on the basis of the intensity- distribution and trend-distribution of the constituent dykes, and Cc.) the discovery of a latent plutonic -complex near Jluck, az a possible "centre" off the rwrth-west coast of Lewis. The trends, thicknesses, and to some extent the dips of small groups of dykes are intimately related to: (i.) the locations of those dykes with respect to the axes of highintensity of both crustal-stretch (dilation) and number of dykes per kilometre, (ii.) the positions of the dykes in relation to the site of the roughly contemporaneous Central Intrusive Coiiplexes, and (iii.) the structure of the country-- rock in which the dykes were emplaced, especially in the cases of the !oinian rocks, the Tertiary lavas, and the peripherally folded Mesozoic rocks bordering the Central Complex of Skye. The form and structure of the dyke-swarms, the distribution of the petrological types of dykes, and the available aeromagnetic, gravity-anomaly, and radiometric-dating evidence, indicate that the emplacement of each dyke-swarm is related to a sone of N.W. transcurrent faulting roughly paralleling the major dilation-axis of the swarm. Such faults were the consequence of differential movement of crustal blocks away from the line of a proposed Tertiary separation (Rockall Trough) of the British mainland and Rockall Plateau. Intracrustal, elongate, ridge-like basaltic magma-reservirs, whose ultimate source was the upper mantle, are believed to have ascended each of these faults. At the intersections of the N.W. transcurrent faults with preexisting N.E. faults cylinders of basaltic magma arose to form the Central Intrusive Complexes. Dyke-swarms developed as offshoots of the basaltic ridges and to a small extent from the basaltic cylinders, under the influence of a N.E. to S.W. tension resulting from a relative separation in this same direction of' the crustal blocks on both sides of the Rockall Trough rift.

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Στη παρούσα διπλωματική εργασία θα μελετηθεί η συμπεριφορά των εναέριων γραμμών μέσης τάσης του νομού Άρτας, όταν αυτές πλήττονται από διάφορα αίτια, τα οποία είναι καταγεγραμμένα μέσω του Συστήματος Αναγγελιών Βλαβών (ΣΑΒ) της ΔΕΗ και βρίσκονται στη διάθεσή μας για το έτος 2011. Τα κυριότερα αυτών είναι τα κεραυνικά πλήγματα και η κακοκαιρία και σε αυτά θα δωθεί βαρύτητα. Σκοπός είναι να εξαχθούν, μέσω θεωρητικών υπολογισμών, κάποια συμπεράσματα για το πως θα συμπεριφέρονται οι γραμμές αυτές ανάλογα με τη τοποθεσία, το ανάγλυφο της περιοχής, το ύψος της γραμμής και διάφορους άλλους παράγοντες που θα αναφερθούν λεπτομερώς στο 3ο κεφάλαιο. Για την καλύτερη κατανόηση όμως των προαναφερθέντων και για να έχουμε μια πιο πλήρη εικόνα επι του αντικειμένου, θα πρέπει αρχικά να γίνει μια συνοπτική παρουσίαση ενός τυπικού συστήματος ηλεκτρικής ενέργειας, αφού πρώτα αναλυθεί στα επιμέρους τμήματά του. Αναγκαία επίσης είναι και η αναφορά της IEEE οδηγίας για τη συμπεριφορά έναντι κεραυνών των εναέριων γραμμών διανομής ηλεκτρικής ενέργειας, μιας και οι επικρατούντες κλιματολογικές – περιβαλλοντολογικές συνθήκες είναι από τις βασικές αιτίες πρόκλησης σφαλμάτων στα εναέρια δίκτυα. / This thesis studies the behavior of medium voltage (distribution) lines of county of Artas, when they are affected by various causes, which are written down from the System Notice Damage of Hellenic Public Power Corporation and are at our disposal for the year 2011. The most important of them are lightning strikes and bad weather, to which extra focus will be given. Our purpose is to conclude through theoretical calculations to the behavior of these lines according to the location, relief area, the line’s height and other factors that will be mentioned in chapter 3. In order to have a complete perception of the subject, a brief presentation of a typical power system will take place after it is analysed in subsections. It is also important to mention the guidelines of Intstitute of Electrical and Electronic Engineers (IEEE) on the behaviour of air power distribution lines against lightning, as the prevailing environmental and climatological conditions are the most essential causes of faults on air lines.