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Hydrodynamic Study of a Suction Stabilized Float (SSF)January 2014 (has links)
abstract: In this work, the hydrodynamics of Suction Stabilization is studied. Suction stabilization was found to stabilize floating platforms/floats in a much better way as compared to the conventional methods. This was achieved by an effective increment in the metacentric height due to the Inverse Slack Tank (IST) effect. The study involves the analysis of the existing designs and optimizing its performance. This research investigates the stability of such floats and the hydrodynamic forces acting on the same for offshore applications, such as wind turbines. A simple mathematical model for the condition of parametric resonance is developed and the results are verified, both analytically and experimentally. / Dissertation/Thesis / Real time working of SSF in heavy wind and rain conditions / Animation explaining working of SSF / Experiment with patio umbrella mounted on SSF / Masters Thesis Mechanical Engineering 2014
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Dynamics of holomorphic correspondences / Dinâmica de correspondências holomorfasCarlos Alberto Siqueira Lima 22 June 2015 (has links)
We generalize the notions of structural stability and hyperbolicity for the family of (multivalued) complex maps Hc(z) = zr + c; where r > 1 is rational and zr = exp r log z: We discovered that Hc is structurally stable at every hyperbolic parameter satisfying the escaping condition. Surprisingly, there may be infinitely many attracting periodic points for Hc. The set of such points gives rise to the dual Julia set, which is a Cantor set coming from a Conformal Iterated Funcion System. Both the Julia set and its dual are projections of holomorphic motions of dynamical systems (single valued maps) defined on compact subsets of Banach spaces, denoted by Xc and Wc, respectively. For c close to zero: (1) we show that Jc is a union of quasiconformal arcs around the unit circle; (2) the set Xc is an holomorphic motion of the solenoid X0; (3) using the formalism of Gibbs states we exhibit an upper bound for the Hausdorff dimension of Jc; which implies that Jc has zero Lebesgue measure. / Generalizamos as noções de estabilidade estrutural e hiperbolicidade para a família de correspondências holomorfas Hc(z) = zr + c; onde r > 1 é racional e zr = exp r log z: Descobrimos que Hc é estruturalmente estável em todos os parâmetros hiperbólicos satisfazendo a condição de fuga. Tipicamente Hc possui infinitos pontos periódicos atratores, fato totalmente inesperado, uma vez que este número é sempre finito para aplicações racionais. O conjunto de tais pontos dá origem ao chamado conjunto de Julia dual, que é um conjunto de Cantor proveniente de um Conformal Iterated Function System. Tanto o conjunto de Julia e quanto seu dual são projeções de movimentos holomorfos de sistemas definidos em subconjuntos compactos denotados por Xc e Wc; respectivamente de um espaço de Banach. Para todo c próximo de zero: (1) mostramos que Jc é reunião de arcos quase-conformes próximos do círculo unitário; (2) o conjunto Xc é um movimento holomorfo do solenóide X0; (3) utilizando o formalismo dos estados de Gibbs, exibimos um limitante superior para a dimensão de Hausdorff de Jc. Consequentemente, Jc possui medida de Lebesgue nula.
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Near-infrared proper motion surveysSmith, Leigh Charles January 2016 (has links)
I present the development of two near infrared proper motion pipelines for high resolution near infrared data from UKIDSS and the VISTA VVV survey. The UKIDSS pipeline is capable of accuracies of order 5-10 mas yr⁻¹ for bright sources with the largest epoch baselines (~ 8 years). The VVV pipeline reaches 1-2 mas yr⁻¹ proper motion precision at the bright end and parallax measurements at ~ 1 mas precision. It will be possible to improve upon the VVV astrometric precision due to increases in data volume and further pipeline development. I have used the proper motion pipelines to generate three near infrared proper motion catalogues of the UKIDSS LAS and GPS and the VVV survey. The LAS proper motion catalogue covers 1500 deg2 at high Galactic latitudes and contains approximately 15 million sources with two J band epochs. The GPS proper motion catalogue covers 1500 deg2 of the northern Galactic plane and contains approximately 400 million sources with two K band epochs. The VVV proper motion catalogue covers 560 deg2 of the Galactic bulge and disc and contains approximately 200 million sources with between 50 and 150 Ks band epochs. I have also produced a preliminary 5σ parallax catalogue containing 3403 VVV sources. The LAS and GPS proper motion catalogues have been used by myself and other authors to identify and study many new examples of high proper motion stars, brown dwarfs, ul-tracool dwarf benchmark candidates, cool white dwarfs, substellar subdwarfs and nearby sources within < 25 pc. These catalogues remain far from fully exploited and will be a useful resource for future research by the astronomical community. Exploitation of the VVV proper motion catalogue is still in its infancy, yet it has already generated large numbers of new high proper motion sources. These include new brown dwarf candi-dates, important benchmark objects, and nearby sources which have previously avoided detection. Parallax results from the VVV pipeline will be useful to improve low mass star/ultracool dwarf luminosity functions, significantly increasing the numbers of brown dwarfs with known parallaxes and illustrates how general purpose multi-epoch wide area surveys can generate parallaxes. Finally, I discuss the long term usefulness of such catalogues in the Gaia era and how they might be exploited in the future.
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Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy WeatherBassler, Christopher Colby 21 June 2013 (has links)
Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on operability, safety, and survivability. Estimation and prediction of the energy transfer and dissipation of the hydrodynamic components, added inertia and damping, is essential to accurately describe the roll motions of a ship. This is especially true for ship operations in moderate to extreme sea conditions. In these conditions, a complex process of energy transfer occurs, which alters the physical behavior of the hydrodynamic components, and ultimately affects the amplitude of ship roll motion.
Bilge keels have been used on ships for nearly two centuries, to increase damping and reduce the severity of roll motions experienced by a ship in waves. Because ship motions are more severe in extreme sea conditions, large roll angles may occur. With the possibility of crew injury, cargo damage, or even capsize, it is important to understand the behavior of the roll added inertia and damping for these conditions. Dead ship conditions, where ships may experience excitation from beam, or near beam, seas present a worst case scenario in heavy weather. The behavior of a ship in this condition should be considered in both the design and assessment of seakeeping performance.
In this study, hydrodynamic component models of roll added inertia and roll damping were examined and assessed to be unsuitable for accurate prediction of ship motions in heavy weather. A series of model experiments and numerical studies were carried out and analyzed to provide improved understanding of the essential physical phenomena which affect the hydrodynamic components and occur during large amplitude roll motion. These observations served to confirm the hypothesis that the existing models for roll added inertia and damping in large amplitude motions are not sufficient. The change in added inertia and damping behavior for large roll motion is largely due to the effects of hull form geometry, including the bilge keels and topside geometry, and their interactions with the free surface. Therefore, the changes in added inertia and damping must be considered in models to describe and predict roll motions in severe wave environments.
Based on the observations and analysis from both experimental and numerical methods, several time-domain model formulations were proposed and examined to model hydrodynamic components of large amplitude roll motions. These time-domain formulations included an analytical model with memory effects, a piecewise formulation, and several possibilities for a bilge keel force model. Although a piecewise model for roll damping was proposed, which can improve the applicability of traditional formulations for roll damping to heavy weather conditions, a further attempt was undertaken to develop a more detailed model specifically for the bilge keel force. This model was based on the consideration of large amplitude effects on the hydrodynamic components of the bilge keel force. Both the piecewise and bilge keel force models have the possibility to enable improved accuracy of potential flow-based numerical prediction of ship roll motion in heavy weather. However, additional development remains to address issues for further practical implementation. / Ph. D.
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FINANCIAL MODELING WITH LE ́VY PROCESSES AND APPLYING LE ́VYSUBORDINATOR TO CURRENT STOCK DATAALMEIDA, GONSALGE SUREKA January 2019 (has links)
No description available.
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Ultrafast Collective Dynamics of Water-Protein InteractionsHouston, Patrick R. January 2020 (has links)
No description available.
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Nonlinear Dynamics of Driveline Systems with Hypoid Gear PairYang, Junyi 30 October 2012 (has links)
No description available.
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Protein Dynamics, Loop Motions and Protein-Protein Interactions CombiningNuclear Magnetic Resonance (NMR) Spectroscopy with Molecular Dynamics (MD)SimulationsGu, Yina January 2016 (has links)
No description available.
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Ultrafast Protein Hydration Dynamics and Water-Protein InteractionsYang, Jin January 2016 (has links)
No description available.
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Calculation of the forces on a moored ship due to a passing container shipSwiegers, Pierre Brink 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: When a sailing ship passes a moored ship the moored ship experiences forces and
moments. These forces and moments cause the moored ship to move. The resulting ship
motions due to the passing ship can sometimes be more severe than the ship motions due
to ocean waves and can cause serious accidents at moorings such as the failing of mooring
lines or even the total break away of the ship from the berth. Since bulk carriers and tankers
were traditionally the largest seafaring ships, passing ship studies have focused mainly on
these vessels, but recently container ships have grown to a comparable size. In this study an
existing numerical model “Passcat” is validated with physical model measurements for a
Post Panamax container ship passing a Panamax bulk carrier. Other existing mathematical
formulae are also evaluated by comparison with these model tests.
In the physical model tests the passing speed (V), passing distance (G), depth draft ratio
(d/D) and the presence of walls and channels were varied. It was found that the passing ship
forces are proportional to the passing speed to the power of 2.32. This is slightly higher than
the generally accepted quadratic relationship for passing ship induced forces. Similar
relationships were found for the other variables.
The numerical model results were compared to the physical model measurements by
determining agreement ratios. A perfect agreement between the numerical and physical
models would result in an agreement ratio of 1. Agreement ratio boundaries, wherein
agreement would be regarded as good, were drawn between 0.7 and 1.3. The numerical
model, Passcat, was found to under predict the passing ship forces. It was found that
Passcat is valid for a wide range of sensitivities and remains within the agreement ratio limits
as long as passing speed is limited to 10 knots (kt), depth draft ratio to more than 1.164,
passing distance to less than four times the moored ship beam (Bm) for surge and sway
estimation and passing distance to less than three times the moored ship beam for yaw
estimations. These limits are true for no structures in the water. For structures in the water
only the passing speed limits are different. When quay walls are present, the surge and
sway forces will only provide acceptable answers at passing speeds below 9kt. When 9Bm
or 12Bm channels are present, the sway force will only provide acceptable answers at
passing speeds below 7kt. When a 6Bm channel is present, the yaw moments will only
provide acceptable answers at passing speeds below 6kt.
From the mathematical model evaluation study it was found that empirical or semi empirical
methods can not provide answers with good agreement to the physical model when walls or
channels are present. For the open water case, it is only the Flory method that can provide
answers with good agreement to the physical model for surge, sway and yaw forces. The
Flory method can provide answers with acceptable agreement within narrow boundaries of
passing distance (1 to 2 times the beam of the moored ship), passing speed (4 kt to 14 kt)
and depth draft ratio (less than 1.7). The numerical model, Passcat can be used with little
effort to provide answers with better agreement to the physical model for a larger range of
variables. / AFRIKAANSE OPSOMMING: Wanneer ’n skip verby ‘n vasgemeerde skip vaar, ondervind die vasgemeerde skip kragte en
momente. Hierdie kragte induseer beweging van die vasgemeerde skip. Die beweging kan
soms groter wees as die effek van wind of golwe. Indien die bewegings groot genoeg is kan
dit van die vasmeer lyne van die skip laat breek, of al die lyne laat breek sodat die skip vry in
die hawe ronddryf. Aangesien erts skepe en tenk skepe vir jare die grootste skepe in the
wêreld was, het die meeste van die skip interaksie studies op daardie skepe gefokus. Die
grootte van behouering skepe het egter in die onlangse tye gegroei om dimensies soortgelyk
aan die van erts en tenk skepe te hê. In hierdie studie word ’n bestaande numeriese model
“Passcat” gestaaf met fisiese model metings op ’n Post Panamax behoueringskip wat verby
‘n Panamax erts skip vaar. Bestaande wiskundige formules is ook getoets deur dit met
dieselfde fisiese model metings te vergelyk. In die fisiese model studie is die spoed van die skip (V), tussenafstand (G), diepte diepgang
verhouding (d/D) en die teenwoordigheid van kaai mure en kanale in die water getoets. Daar
is gevind dat die kragte op die vasgemeerde skip direk eweredig is aan die spoed van die
skip tot die mag 2.32. Dit is effens meer as die algemeen aanvaarde kwadratiese verhouding
tussen vloeistof sleurkrag en vloeisnelheid asook tussen skip interaksie kragte en vaar
snelheid. Soortgelyke verhoudings is vir al die veranderlikes bereken.
Numeriese model resultate is vergelyk met die fisiese model om die verhouding van
ooreenstemming te bepaal. ’n Perfekte ooreenstemming word voorgestel deur ’n verhouding
van ooreenstemming van 1. Grense waarbinne die verhouding van ooreenstemming as
goed beskou word is getrek tussen 0.7 en 1.3. Daar is gevind dat die numeriese model,
Passcat, kragte oor die algemeen onderskat. Passcat is geldig vir 'n breë reeks van
veranderlikes en sal geldig bly solank die skip spoed tot 10 knope, diepte diepgang
verhouding tot meer as 1.164, tussenafstand tot minder as vier skipwydtes (Bm) vir 'surge'
en 'sway' kragte en tot minder as drie skipwydtes vir 'yaw' momente beperk word. Hierdie
grense is opgestel vir geen strukture in die water. Vir strukture in die water word slegs die
skip spoed aangepas. Wanneer daar mure in die water is sal 'surge' en 'sway' slegs geskikte
antwoorde gee as die skip spoed tot 9 knope beperk word. Vir 9Bm of 12Bm kanale sal
geskikte antwoorde vir 'sway' kragte slegs voorkom met 'n skip spoed minder as 7 knope. Vir
6Bm kanale sal geskikte antwoorde vir 'yaw' momente slegs voorkom met 'n skip spoed van
minder as 6 knope. Van die wiskundige model evaluasie studie is gevind dat empiriese of semi empiriese
metodes nie resultate met goeie ooreenstemming tot the fisiese model metings kan gee,
wanneer daar kaai of kanaal mure in die water is nie. Vir die oopwater geval is dit slegs die
Flory metode wat antwoorde kan voorsien wat goed ooreenstem met die fisiese model vir
'surge', 'sway', en 'yaw' kragte. Die Flory metode voorsien hierdie resultate binne noue
grense vir tussenafstand (1 tot 2 wydtes van die vasgemeerde skip), verbyvaar spoed (4
knope tot 14 knope) en diepte diepgang verhouding (minder as 1.7). Die numeriese model,
Passcat, kan met min moeite antwoorde bereken wat beter ooreenstemming vir 'n groter
reeks veranderlikes gee.
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