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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

An Application of Neural Network ¡V Tide Forecasting and Supplement In the South China Sea

Chun, Chu-Chih 17 July 2000 (has links)
In the design and plan of the coast engineering, long-term and continual tidal database represent the indispensable role. This paper collect the tidal database, their locations include the ocean around the Taiwan and the South China Sea. Use the artificial neural networks (ANN) to build model and find the relationship between neighbor tidal observation stations. There are many reasons to cause the tide phenomenon, include the tide generating force, season, coastal geography, geography of sea floor, resonance of gulf or estuary, change depth of sea, and so on, it will be determined by local environment. The tide analysis and prediction usually use the harmonic analysis method. This method need long-term and continual tidal record, and the theory depend on the tide generating force, it has limit about accuracy. The application of artificial neural networks is used in nonlinear science problems in general cases. The back propagation (BP) networks is the one model of the artificial neural networks, this paper use ANN-BP model to build the relationship from different tide observed stations, and verify the quality of model. From the result of verified models, the ANN-BP model can predict and supplement the tide record very well. The items of research include: ¡i1¡j the relationship between two neighbor tide observed stations. (one station input, one station output) ¡i2¡jthe relationship between three neighbor tide observed stations. (two station input, one station output) ¡i3¡j input several tide observed stations and output one station. ¡i4¡j the correlation of connected weight and threshold between different models. ¡i5¡j change the parameters of ANN-BP model and discus the affect of model¡¦s quality. ¡i6¡j application of truly case. From the result of this paper, in the design and plan of the coast engineering, the long-term tide observed record can be predict from the ANN-BP model and tide record of neighbor observed stations. When the tide record has miss or lost cause by machine or other reasons, the ANN-BP model can supplement the lost tide record well. This paper show the ANN-BP model can be apply to predict and supplement the tide record very well, and will be possible applied method.
82

Numerical modeling of flow dynamics and water exchange in the Kaohsiung Harbor

Chuang, Shih-Chiao 31 January 2002 (has links)
Abstract Kaohsiung Harbor is one of the most important international sea ports in the world. Due to the long-standing lack of in-situ current data, the complex variations of the flow field in this basin still remain unclear. As a consequence, the related environmental problems such as oil spills, water quality management and ship maneuvering safety , have long been a great concern in this harbor. The present study is conducted to better understand the flow field in the Kaohsiung Harbor. A series of synoptic flow observations of the Kaohsiung Harbor were conducted by using towed-ADCP or EM current meters. From these observations it can be shown that the flow field of the Kaohsiung Harbor is¡GWater entering the harbor through the second entrance and exiting the harbor through the first entrance during ebbs. During floods the flows are reversed. A 3-D numerical model (from POM) is developed for the Kaohsiung Harbor. The flows are more complicated by the M2 tide driven than by the mixed tide driven. From the results by the M2 tide driven show the ocean current is variable, especially the south ocean current. Therefore, the flows are more complicated owing to the mixed tidal characteristics and shoreline geometry. The maximum current speeds amount to 30 - 40 cm/s in the narrow first entrance and 10 - 20 cm/s in the second entrance. It is clearly demonstrated from the model results that drainage from the Chien-Chen River affects greatly the salinity and circulation patterns of the Kaohsiung Harbor, causing the salinity of the first entrance to be lower than that of the second entrance, and the surface layers flowing outward toward the ocean while the lower layers displaying tidal oscillations. From the modeling results, the influence of the wind on the harbor flows is insignificant and the tide is main force in the harbor. Under the simultaneous forcing of river and wind, flood and ebb tidal streams leaving the two entrances are found to diverge in a flow stagnation area inside the harbor near Pier 45 and 61, respectively. Based on the modeling results, it can be concluded that the main factors affecting the flow patterns of the Kaohsiung Harbor are (1) mixed tidal nature, (2) shoreline geometry and (3) river runoff
83

A Study of Internal Tidal Displacement of Watermass in Gaoping Submarine Canyon based on Echo Intensity and Hydrographic Data

Lin, Sheng-Chin 10 February 2009 (has links)
The internal tide in GPSC¡]Gaoping submarine canyon¡^is the main factor controlling the movement of watermasses. In order to improve our understanding on the compact of suspended sediment exchange in and out GPSC, the data used in this study are collected from four cruises of field observations using research vessel OR3. Instruments deployed include ADCPs¡BEK500¡BCTD and vertical string of temperature loggers. The collected data are analyzed through a variety of time series analysis technique, such as harmonic analysis¡BFFT and EOF. The results show that¡]1¡^the echo intensity recorded by ADCP through calibration could reduce the decay of echo with the distance. The results seem useful to apply in watermass behavior studies.¡]2¡^ Echo intensity with calibration were comparable with signal recorded by EK500 which could be validated to each other. These observations were related to sediment resuspension influenced by internal tide. ¡]3¡^There were two layers of large turbidity, at the depth of canyon edge and near the bottom of canyon, both were fluctuated with two interval tidal frequency.¡]4¡^Another band of echo intensity fluctuations, not directly correlate to sediment resuspension, was likely due to vertical migration, of zooplankton or biology effects.
84

Red tides and algal blooms in subtropical Hong Kong waters: field observations and Lagrangianmodeling

Wong, Tse-man, Ken, 黃子文 January 2004 (has links)
published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
85

Brevetoxins in marine birds: Evidence of trophic transfer and the role of prey fish as toxin vector

Van Deventer, Michelle 01 June 2007 (has links)
Harmful algal blooms (HABs) of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along the central west coast of Florida. Mass mortalities of marine birds have long been associated with these blooms, yet there is little data documenting the accumulation of brevetoxins in the tissues of birds and their prey items. An intense HAB event impacted the region from Tampa Bay to Charlotte Harbor during most of 2005. More than one hundred marine birds, representing twenty three species, were collected during this bloom. All birds sampled were found dead or had died within 24 hours of admittance to local wildlife rehabilitation centers. In order to determine if fish were vectors for brevetoxin ingestion, the stomach contents of all birds were examined and any recovered fish were identified to the extent possible. The gastrointestinal tissues and contents from all avian samples were analyzed for brevetoxin levels, with results ranging from Shorebirds and gulls may also be exposed to brevetoxins via scavenging of red tide-killed fish deposited on beaches during blooms. Samples from scavenged fish were found to have brevetoxin levels ranging from 31 to 95,753 ng PbTx per gram tissue.
86

An intertidal survey of Cape d'Aguilar, Hong Kong with special reference to the ecology of high-zoned rock pools

Cheung, Pui-shan, Catherine., 張佩珊. January 1991 (has links)
published_or_final_version / Zoology / Master / Master of Philosophy
87

The Energetic Demand of Low Tide Stress on Balanus glandula Under Varying Thermal Conditions

Hendrix, Alicia M 01 January 2012 (has links)
Like all intertidal species, the barnacle Balanus glandula must cope with temperature and desiccation stress during daily low tide exposure. The increase in temperature at low tide leads to both increased metabolic rate and the potential for increased ATP demand. With its additional inhibition of oxygen intake, low tide thus has an energetic cost that is often reflected in an increase in oxygen consumption following resubmersion. As anthropogenically induced global climate change increases air and water temperatures, its cost might increase. B. glandula individuals were exposed to 4‑hour low tides with maximal temperatures of 18, 30, 35, and 38°C, and their oxygen consumption rates and behaviors were recorded for 4 hours upon resubmersion. It was found that aerial respiration could be measured, though aerial rates were only a fraction of aquatic rates. It was further found that relative aquatic oxygen consumption rates were not elevated following low tide for any temperatures. However, B. glandula individuals exposed to 35 and 38°C low tides remained active a significantly greater portion of time through the first and second hours of recovery, respectively. This indicates that a low tide stress effect is evident in B. glandula, but that it manifests not as an increase in the respiration rate when active, but rather as an increase in the overall activity time. Thus, with increasing global temperatures B. glandula will likely have increased energy needs. This might lead to range relocations, a drive to find new energy sources, and/or reallocations of energy budgets.
88

Modeling and Data Analysis of Large Ring Laser Gyroscopes

Tian, Wei 30 January 2014 (has links) (PDF)
Ringlaser dienen dazu, durch genaue inertiale Messungen Rotationen ohne Bezug auf ein externes Referenzsystem lokal und praktisch in Echtzeit zu bestimmen. Sie wurden in den 1970er Jahren insbesondere für die Navigation von Flugzeugen entwickelt. In den letzten Jahrzehnten wurden Ringlaser dann so weit verbessert, dass sie nun auch als eigenständige Messinstrumente in der Geodäsie Verwendung finden. Aufgrund der erreichbaren Genauigkeit ist es inzwischen möglich, Variationen in der Erdrotation mit der dafür erforderlichen Präzision zu detektieren. Der stabilste unter den Ringlasern, der so genannte Ringlaser "G" der geodätischen Fundamentalstation Wettzell, erreicht eine Sensitivität von 1.2 x 10 -11 nrad. Damit ist dieses Instrument in der Lage, Neigungen von bis zu 1 nrad (dies entspricht einem Signal von 0.2 mas in der Polbewegung, in Änderung der Rotationsgeschwindigkeit der Erde) im täglichen und halb-täglichen Frequenzband zu messen. Motivation dieser Arbeit ist es, der in den letzten Jahren erreichten Verbesserung des Auflösungsvermögens und der Sensorstabilität Rechnung zu tragen und die für die Auswertung von Ringlaserdaten benutzten geophysikalischen Modelle weiter zu verbessern, um dadurch die variable Rotation der Erde noch präziser vermessen zu können. Die dafür relevanten Effekte werden in den einzelnen Kapiteln dieser Arbeit separat behandelt. Nach einer Einführung werden in Kapitel 2 dieser Arbeit drei lokale, topozentrische Koordinatensysteme konstruiert, mit welchen sich das zu beobachtende Sagnac-Signal eines Ringlasers in der ersten post-Newtonischen Näherung der Allgemeinen Relativitätstheorie adäquat beschrieben lässt. In Kapitel 3 wird ein verbessertes Modell für die Orientierung des Ringlasers, basierend auf Ergebnissen von Dehant et al. (1999), entwickelt. Ein in den bislang benutzten Modellen vernachlässigter Neigungsterm konnte dabei identifiziert werden. Ein Modell für die retrograde tägliche Polbewegung der Erde wird in Kapitel 4 entwickelt. Ausgehend von den dynamischen Gleichungen für eine starre Erde werden diese um elastische Effekte und Einflüsse der Mehrschichtigkeit der Erde ergänzt und die entsprechenden Euler-Liouvilleschen Gleichungen und Transfer-Funktionen abgeleitet. Gezeiteneinflüsse des Ozeans, speziell die dadurch hervorgerufene sub-tägliche Variation der Erdrotation und ozeanische Auflasteffekte, werden in Kapitel 5 behandelt. Es wird gezeigt, dass die ozeanischen Signale größer als 10 -9 Δf0 (Δf0 348 Hz für den Ringlaser "G") sind und damit in den Messdaten des Ringlasers "G" nachweisbar sein sollten. Auf Grundlage der in dieser Arbeit entwickelten Modelle wurde eine 168 Tage (30. April 17. Oktober 2010) umfassenden Datenreihe des Ringlasers "G" in Kapitel 6 ausgewertet. Für die Auswertung wurde die Software ETERNA 3.40 genutzt und entsprechend angepasst. Die tägliche retrograde Polbewegung konnte dabei mit einer Genauigkeit von 0.15 mas bestimmt werden. Diese Auswertung beweist ein weiteres Mal die Existenz eines flüssigen Erdkerns. Des weiteren konnte gezeigt werden, dass bestimmte Gezeitenparameter des halb-täglichen Frequenzbandes durch lokale Effekte beeinflusst werden. Lokal gemessene Luftdruckdaten wurden benutzt, um den Einfluss atmosphärischer Auflasteffekte auf den Ringlaser "G" zu untersuchen. Die Ergebnisse dieser Arbeit zeigen, dass sich für diese Effekte kein signifikanter Einfluss nachweisen lässt. Die Arbeit schließt mit einer Zusammenfassung der Resultate, einer Beschreibung der sich ergebenden Schlussfolgerungen und einem Ausblick auf zukünftige Arbeiten auf dem Gebiet der Ringlaseranalyse. / Ring laser gyroscopes measure inertial rotations locally and in real-time without the need for an external reference system. Initially, they were developed for aircraft navigation applications in the 1970s. With the improvement of ring laser technology during the last decades large ring laser gyroscopes (RLGs) are nowadays used as independent geodetic instruments. Due to the achievable accuracy more and more geophysical signals become observable in the data. The G-ring located at the Geodetic Observatory Wettzell is reckoned as the most stable one amongst the running large RLGs and reaches a sensitivity of 1.2 x 10 -11 nrad. Therefore, the instrument is able to detect a tilt signal of 1 nrad (equivalent to a signal of 0.2 mas in polar motion or 10 -9 Ω0 in variation of Earth rotation rate) in the diurnal and semi-diurnal band. This motivates us to improve previous geophysical models and estimate associated tilt and Earth rotation signals, which are the focuses of this Thesis. Firstly, we construct three local proper topocentric reference frames and interpret the Sagnac effect observed by large RLGs in the first post-Newtonian (PN) approximation of Einstein's theory of gravity. Secondly, in Chapter 3 we develop an improved orientation model for the Sagnac platform, based on the numerical results of Dehant et al. (1999). A missing tilt term in previous RLG tilt models is found. In Chapter 4, based on the Euler-Liouville equations or nutation transfer functions for a rigid Earth, a purely elastic Earth, a two-layered Earth and a three-layered Earth, five retrograde diurnal polar motion models are computed with the HW95 tidal potential catalogue. Thirdly, ocean tide effects (two aspects: effects on sub-daily variations of Earth rotation and loading effect on tilt) are considered in Chapter 5. We show that the Sagnac signals induced by ocean tides are larger than 10 -9 Δf0 (Δf0 348 Hz for the G-ring) and their influences are visible in the G-ring. Fourthly, based on the above-mentioned improved models and 168 days (from Apr.30 to Oct.17 in 2010) of G-ring data, in the diurnal band, we estimate the retrograde diurnal polar motion signal with an accuracy of 0.15 mas. The Earth tide software ETERNA 3.40 was adopted and modified to analyse this data. Our estimation provides one more evidence for the existence of the Earth's fluid outer core. Furthermore, we found that the tidal parameters for the G-ring are affected by the cavity and topographic effects in the semi-diurnal band. The local air pressure record is used in order to investigate the atmospheric loading effect on the G-ring by a simple regression model. Nevertheless, the preliminary result shows that no significant influence from atmospheric loading on our estimation is found. This Thesis closes with a summary of the obtained results, conclusions and suggestions how the analysis of ring laser data could be improved in future work.
89

Characterization of novel compounds isolated from Karenia brevis cultures

Truxal, Laura T. January 2008 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2008. / Includes appendixes. Title from PDF title page (viewed May 27, 2009) Includes bibliographical references (p. 96-102)
90

Microbial food web interactions in two Long Island embayments /

Cellineri, Katie Rose Boissonneault. January 1999 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1999. / Includes bibliographical references (leaves 23-30).

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