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A Novel Overtopping Wave Energy Device Concept Applied to California
Full text linkThis thesis explores a novel concept in the area ofovertopping ocean wave energy devices. Current models ofovertopping devices are limited to locations which experience largewave activity. The high energy associated with large waves enablesthe ocean water waves to overtop the device ramp into thecollection reservoir which discharges through a power generatingturbine. The ramp height is necessarily large to establish asufficient collection reservoir head. The proposed design conceptcan utilize small waves by implementing a gearing system which cantransfer water to the collection reservoir. This allows for greateraccess to the wave energy resource at more locations than currentlypossible.After providing background to ocean wave energy devices thewave resources of the California coast is investigated. Theformulation for wave energy is established and a statisticalanalysis of eight locations from northern to southern California isprovided. Next important aspects for overtopping as well asovertopping formulas are presented.The modeling of an overtopping device with a gearing systemis presented and examined for a range of variables important toovertopping. An analysis of the proposed design concept showspromise for higher power output in the smaller wave environments ofsouthern California. Additionally for all locations considered thegearing system concept improves power output over a conventionalovertopping device for some portion of the time. In addition,survivability issues important for devices in the ocean environmentare treated using extreme value analysis and further areas ofresearch are suggested for future work
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Experimental determination of stresses in a ship's bottom structure.
Full text linkThis thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title.An attempt is made to verify second order orthotropic plate theory using a Plexiglas model loaded laterally and in the plane of the plate. The design and construction of the model, loading system, support system and instrumentation are discussed in detail. The experiments did not verify second order orthotropic plate theory. The main reason was the inability of the boundary condition members to apply the designed boundary conditions to the plate. Further attempts to verify the theory are possible with the same apparatus if boundary modifications are made.http://archive.org/details/experimentaldete109451499
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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Long-Term Properties and Combinations of Stochastic Hull Girder Loads on Ships
Full text linkThis dissertation presents a novel simulation-based method which provides a consistent and rational framework for long-term hull girder load combination analysis. During its lifetime, which is typically a period of 20 to 25 years (long-term), a ship structure will be subjected to many different dynamic loads. Most of them are caused by very harsh and constantly changing ocean environment and they are random. Therefore, methods of classical statistics and time series analysis have to be applied in order to analyze the structural response to these loads. Many of currently available methods rely on the assumption of weak stationarity of the wave elevation process. This assumption usually holds for a period of up to three hours (short-term) and these methods cannot be used to analyze long-term statistical properties of the loads and their combinations. Long-term methods that can handle the non-stationarity of the wave elevation process often involve many assumptions and require the knowledge of short-term probability density functions of loads or their linear and nonlinear combinations as well as the joint probability density functions of multiple random variables having an impact on these loads.The method presented in this dissertation is based on efficient multi-voyage simulations of properly correlated hull-girder loads. It relies on a comprehensive statistical model from which nine relevant variables that have an impact on the hull-girder load spectral densities can be simulated or sampled using the rejection sampling technique. These nine variables are: significant wave height, zero crossing wave period, prevailing wind and wave direction, ship's relative heading with respect to waves, ship's location, season of the year, ship's speed, voluntary and involuntary speed reductions in severe sea states and the ship's loading condition. The rejection sampling can significantly decrease the number of sea state and operational profile combinations that have to be considered in the long-term analysis. Non-stationary wave elevations during the ship's entire life are treated as a sequence of different short-term weakly stationary Gaussian stochastic processes, each of which is two hours long. Hull girder sectional loads during each short-term period are efficiently simulated from the load spectral densities taking into account their relative phase differences. Multi-voyage long time series of various load combinations, including the nonlinear ones, are obtained and their correlation structure and other statistical properties are examined. Nonlinearities in the vertical bending moment (VBM) and the hydroelastic response of the ship in the form of springing and whipping are also included in the simulation. Slamming events are determined from the linear motion analysis and the subsequent whipping response of the structure is simulated in time domain using a combination of trapezoidal and finite element methods to numerically solve dynamic Timoshenko beam problem. Nonlinearities have a significant effect on the simulation time. However, neglecting the super and subharmonics of small amplitudes significantly reduces simulation time while retaining reasonable accuracy. This makes it possible to use simulation even at the initial stages of ship design process. Although some assumptions are necessary when calculating the loads on a ship structure, the main advantages of the simulation method are that it doesn't make assumptions about the statistical nature of these loads, and it enables nonlinear combinations of linear and nonlinear loads even when their theoretical short-term probability distributions don't exist. Three different ship types; container ship, tanker and bulk carrier, navigating in the North Atlantic, North Pacific, and between Europe and Asia are used to demonstrate the capabilities of the simulation method in three different areas of hull-girder structural analysis: load combinations, extreme value, and fatigue analysis. Correlation structure between all six sectional loads is examined as well as some linear and nonlinear load combinations. The effect of ship route, damping ratio, slamming extent, hydroelasticity, and nonlinearities on the long-term exceedance probabilities of the VBM are also examined. Finally, the fatigue behavior of a selected container ship is studied on all three routes. The total fatigue damage caused by the vertical bending stresses is separated into damage caused by low- and high-frequency VBM components. The high-frequency part is further divided into the damage caused by linear springing, nonlinearities (including nonlinear springing), and whipping.Linear springing does not have a significant effect on the long-term exceedance probabilities of the VBM, but has a significant effect on the fatigue life of the structure. Nonlinearities, on the other hand, have a significant effect on the exceedance probabilities of the VBM and its extreme values as well as on the fatigue life of the structure. Damping ratio has a relatively significant effect on the nonlinear component of the VBM, but does not significantly affect the long-term exceedance probabilities of the total VBM since the damping effects are only pronounced in moderate sea states with steep waves. Nonlinearities are also largest in these sea states.Whipping alone has a relatively small effect on the exceedance probabilities of the VBM and also on the fatigue life of the post-Panamax container ship analyzed in this work. This is attributed to the lack of strong positive correlation in time between whipping peaks and the peaks of the global VBM. More research is needed on studying the phase relationship between these peaks for different ship types, sizes and routes.Simulation method results agree very well with the full-scale measurements taken on board ships in service in terms of linear and nonlinear VBM exceedance probabilities and fatigue life predictions. For ships studied in this work, the simulation outperforms some existing and commonly used long-term methods in terms of accuracy
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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