MIMS EPrints
Not a member yet
2151 research outputs found
Sort by
OCEAN CURRENT PREDICTION IN TOWED CABLE HYDRODYNAMICS UNDER DYNAMIC STEERING
Get PDFThis paper considers the problem of reconstructing the velocities of o
cean currents impinging on a towed streamer cable sparsely equipped with steerin
g elements. The study is based on a two-dimensional model describing the quasi-s
teady motion of the towed cable in the presence of hydrodynamic drag and steerin
g forces that depend nonlinearly on the angle of attack. To derive the proposed
methodology we firstly outline the hydrodynamic equations used in solving the for
ward problem by which the cable’s velocity, curvature and tension are obtained i
n the knowledge of the towing vessel’s motion, the ocean current velocities and
the drag coefficient characteristics of the steering elements. In sequence we form
ulate the inverse problem of inferring the ocean velocities using a finite set of
noise-infused positioning and tension measurements showing that this is nonline
ar and ill-posed. To solve the inverse problem we adopt Newton’s scheme for nonl
inear convex problems in conjunction with generalized Tikhonov regularization. T
he problem under consideration bares significant differences from the linear non-s
teered formulation addressed in (12), due to the nonlinearity in the forward met
hod as well as the discontinuities observed in the forward measurements due to t
he steering forces. A series of numerical simulation studies is subsequently pre
sented in order to demonstrate the practical performance of the proposed techniq
ue in reconstructing the ocean currents velocity profile and angle of attack
A Note on Binary Inductive Logic
Get PDFWe consider the problem of induction over languages containing binary
relations and outline a way of interpreting and constructing a class of
probability functions on the sentences of such a language. Some principles
of inductive reasoning satisfied by these probability functions are discussed,
leading in turn to a representation theorem for a more general class of
probability functions satisfying these principles
Remarks on -definability without the equality test over the Reals
Get PDFIn this paper we study properties of Σ–definability over the reals without the equality test which is one of the main concepts in the logical approach to computability over continuous data. It has been shown that a set is Σ–definable without the equality test if and only if is c.e. open. If we allow the equality test, the structurR^nR^n$? It this paper we give the negative answer to this question
On the difference \pi(x) - li(x)
Get PDFA full exposition of Littlewood's proof that the sign of \pi(x) - li(x) changes infinitely many times.
So, where is the first crossover? In 2008, the best upper bound for the first crossover was due to Chao-Plymen, now published in Int. J. Number Theory 6 (2010) 681 - 690.
The emphasis in this dissertation is on the mathematical analysis involved in the proofs
BASES, FILTRATIONS AND MODULE DECOMPOSITIONS OF FREE LIE ALGEBRAS
No full textWe use Lazard Elimination to devise some new bases of the free Lie
algebra which (like classical Hall bases) consist of Lie products of left
normed basic Lie monomials. Our bases yield direct decompositions
of the homogeneous components of the free Lie algebra with direct
summands that are particularly easy to describe: they are tensor
products of metabelian Lie powers. They also give rise to new
filtrations and decompositions of
free Lie algebras as modules for groups of graded
algebra automorphisms. In particular, we obtain some new
decompositions for free Lie algebras and free restricted free Lie
algebras over fields of positive characteristic
Cylindrical Wiener processes
Get PDFIn this work cylindrical Wiener processes on Banach spaces are defined by means of cylindrical stochastic processes, which are a well considered mathematical object. This approach allows a definition which is a simple straightforward extension of the real-valued situation. We apply this definition to introduce a stochastic integral with respect to cylindrical Wiener processes. Again, this definition is a straightforward extension of the real-valued situation which results now in simple conditions on the integrand. In particular, we do not have to put any geometric constraints on the Banach space under consideration. Finally, we relate this integral to well-known stochastic integrals in literature
The Generalized Singular Value Decomposition and the Method of Particular Solutions
Get PDFA powerful method for solving planar eigenvalue problems is the
Method of Particular Solutions (MPS), which is also well known under
the name ``point matching method''. The implementation of this
method usually depends on the solution of one of three types of
linear algebra problems: singular value decomposition, generalized
eigenvalue decomposition, or generalized singular value
decomposition. We compare and give geometric interpretations of
these different variants of the MPS. It turns out that the most
stable and accurate of them is based on the
Generalized Singular Value Decomposition. We present results to this
effect and demonstrate the behavior of the generalized singular
value decomposition in the presence of a highly ill-conditioned
basis of particular solutions
Spatial interaction among nontoxic phytoplankton, toxic phytoplankton, and zooplankton:Emergence in space and time
Get PDFIn homogeneous environments, by overturning the possibility of competitive exclusion among phytoplankton species, and by regulating the dynamics of overall plankton population, toxin-producing phytoplankton (TPP) potentially help in maintaining plankton diversity—a result shown recently. Here, I explore the competitive effects of TPP on phytoplankton and zooplankton species undergoing spatial movements in the subsurface water. The spatial interactions among the species are represented in the form of reaction-diffusion equations. Suitable parametric conditions under which Turing patterns may or may not evolve are investigated. Spatiotemporal distributions of species biomass are simulated using the diffusivity assumptions realistic for natural planktonic systems. The study demonstrates that spatial movements of planktonic systems in the presence of TPP generate and maintain inhomogeneous biomass distribution of competing phytoplankton, as well as grazer zooplankton, thereby ensuring the persistence of multiple species in space and time. The overall results may potentially explain the sustainability of biodiversity and the spatiotemporal emergence of phytoplankton and zooplankton species under the influence of TPP combined with their physical movement in the subsurface water