DSpace Collection:
https://dspace.lboro.ac.uk/2134/2484
2016-12-05T00:36:21ZCompetitive analysis of interrelated price online inventory problems with demands?
https://dspace.lboro.ac.uk/2134/23318
Title: Competitive analysis of interrelated price online inventory problems with demands?
Authors: Han, Shuguang; Hu, Jueliang; Zhou, Diwei
Abstract: This paper investigates the interrelated price online inventory problems in which decisions as to when and how much to replenish must be made in an online fashion to meet some demand even without concrete knowledge of future prices. The objective of the decision maker is to minimize the total cost with the demands met. Two different types of demand are considered carefully, which are linearly related demand to
price and exponentially related demand to price. In this paper, the prices are online with only the price range variation known in advance, which are interrelated with the preceding price. Two models of price correlations are investigated. Namely an exponential model and a logarithmic model. The corresponding algorithms of the problems are developed and the competitive ratio of the algorithms are also derived by the solutions of linear programming.
Description: This paper is embargoed until six months after publication.2016-01-01T00:00:00ZDomain decomposition methods for domain composition purpose: Chimera, overset, gluing and sliding mesh methods
https://dspace.lboro.ac.uk/2134/23282
Title: Domain decomposition methods for domain composition purpose: Chimera, overset, gluing and sliding mesh methods
Authors: Houzeaux, G.; Cajas, J.C.; Discacciati, Marco; Eguzkitza, B.; Gargallo-Peiro, A.; Rivero, M.; Vazquez, M.
Abstract: Domain composition methods (DCM) consist in
obtaining a solution to a problem, from the formulations of the same problem expressed on various subdomains. These methods have therefore the opposite objective of domain
decomposition methods (DDM). Indeed, in contrast to
DCM, these last techniques are usually applied to matching
meshes as their purpose consists mainly in distributing the
work in parallel environments. However, they are sometimes
based on the same methodology as after decomposing,
DDM have to recompose. As a consequence, in the
literature, the term DDM has many times substituted DCM.
DCM are powerful techniques that can be used for different
purposes: to simplify the meshing of a complex geometry
by decomposing it into different meshable pieces; to perform
local refinement to adapt to local mesh requirements;
to treat subdomains in relative motion (Chimera, sliding
mesh); to solve multiphysics or multiscale problems, etc.
The term DCM is generic and does not give any clue about
how the fragmented solutions on the different subdomains
are composed into a global one. In the literature, many
methodologies have been proposed: they are mesh-based,
equation-based, or algebraic-based. In mesh-based formulations,
the coupling is achieved at the mesh level, before the governing equations are assembled into an algebraic
system (mesh conforming, Shear-Slip Mesh Update,
HERMESH). The equation-based counterpart recomposes
the solution from the strong or weak formulation itself, and
are implemented during the assembly of the algebraic
system on the subdomain meshes. The different coupling
techniques can be formulated for the strong formulation at
the continuous level, for the weak formulation either at the
continuous or at the discrete level (iteration-by-subdomains,
mortar element, mesh free interpolation). Although
the different methods usually lead to the same solutions at
the continuous level, which usually coincide with the
solution of the problem on the original domain, they have
very different behaviors at the discrete level and can be
implemented in many different ways. Eventually, algebraic-
based formulations treat the composition of the
solutions directly on the matrix and right-hand side of the
individual subdomain algebraic systems. The present work
introduces mesh-based, equation-based and algebraicbased
DCM. It however focusses on algebraic-based
domain composition methods, which have many advantages
with respect to the others: they are relatively problem
independent; their implicit implementation can be hidden
in the iterative solver operations, which enables one to
avoid intensive code rewriting; they can be implemented in
a multi-code environment.
Description: This paper is closed access until 9th November 2017.2016-01-01T00:00:00ZHydro-acoustic frequencies of the weakly compressible mild-slope equation
https://dspace.lboro.ac.uk/2134/23262
Title: Hydro-acoustic frequencies of the weakly compressible mild-slope equation
Authors: Renzi, Emiliano
Abstract: We present a novel analytical solution for hydro-acoustic waves in a weakly compressible fluid over a slowly varying bottom. Application of a multiple-scale perturbation technique and matched asymptotic analysis leads to a uniform analytical solution of the depth-averaged
governing equations in three dimensions. We show that the slow depth variation plays a leading-order effect on the evolution of the normal mode amplitude and direction. This dynamics is much richer than the two-dimensional limit analysed in previous studies. For tsunamigenic disturbances, we show that the hydro-acoustic wave field is made up by longshore trapped and offshore propagating components, which were not explicated in previous work. For a plane beach, we find an exact analytical solution of the model equation in terms of integrals of Bessel functions. Our model offers a physical insight into the evolution of hydro-acoustic waves of interest for the design of tsunami early warning systems.
Description: This paper is embargoed until six months after publication.2016-01-01T00:00:00ZV-systems, holonomy Lie algebras and logarithmic vector fields
https://dspace.lboro.ac.uk/2134/23214
Title: V-systems, holonomy Lie algebras and logarithmic vector fields
Authors: Feigin, M.V.; Veselov, A.P.
Abstract: It is shown that the description of certain class of representations
of the holonomy Lie algebra g Δ associated to hyperplane arrangement is Δ essentially equivalent to the classification of V-systems associated to Δ. The flat
sections of the corresponding V-connection can be interpreted as vector fields, which are both logarithmic and gradient. We conjecture that the hyperplane
arrangement of any V-system is free in Saito's sense and show this
for all known V-systems and for a special class of V-systems called harmonic,
which includes all Coxeter systems. In the irreducible Coxeter case the potentials
of the corresponding gradient vector fields turn out to be Saito flat coordinates, or their one-parameter deformations. We give formulas for these deformations as well as for the potentials of the classical families of harmonic V-systems.
Description: This paper is closed access until published.2016-01-01T00:00:00Z