Search results for " Opera"
showing 10 items of 3606 documents
Some consistency issues in multi-criteria decision making
2017
The complexity of decision-making problems included under the multi-criteria decision-making (MCDM) paradigm has favored the proliferation of many schools of thought and varied methodologies. It has not yet been possible to prove the supremacy of any of these approaches. Moreover, in some cases it is difficult to combine the theoretical validity of the approximations with their practical appropriateness. It seems that rigor and applicability are two opposing concepts, something that should not be so. It is our responsibility to bridge the gap. To reduce the gap between theory and practice and use effective methodological approaches, it is necessary to combine the rigor and objectivity of tr…
A Multi objective inventory model for short food supply chains
2017
Over the past 50 years, vertically integrated multinationals dominated global food markets by providing huge product diversity at low prices. Such systems are characterized by long supply chains capable of achieving high cost efficiencies resulting from the use of cheap raw materials, high chemical inputs, industrial shelf-life extension processes, economies of scale and mechanization. This dominant position on the market, however, has been achieved at a heavy cost on the global environment, generated by massive food wastage, and by a steady supply of fossil fuels. For such reasons, global supply chains are considered unsustainable and new food systems are being promoted in order to replace…
Stimulant-induced adaptations in neostriatal matrix and striosome systems: Transiting from instrumental responding to habitual behavior in drug addic…
2005
Abstract Converging evidence indicates that repeated exposure to motor stimulants such as cocaine and amphetamine produces marked alterations in network responsiveness of striatal neurons to subsequent challenge with the same stimulant drug. Such alterations, which correlate with persistent patterns of repetitive behavior, associate with distinct compartmental changes in the neostriatum. Striatal matrix system neurons undergo “silencing” following repeated drug challenges, allowing striosome system neurons to exhibit preferential activation. Matrix neurons are innervated by sensory and motor areas of neocortex and are activated in the course of on-going, adaptive behavior. Inactivation of m…
Locally convex quasi $C^*$-normed algebras
2012
Abstract If A 0 [ ‖ ⋅ ‖ 0 ] is a C ∗ -normed algebra and τ a locally convex topology on A 0 making its multiplication separately continuous, then A 0 ˜ [ τ ] (completion of A 0 [ τ ] ) is a locally convex quasi ∗-algebra over A 0 , but it is not necessarily a locally convex quasi ∗-algebra over the C ∗ -algebra A 0 ˜ [ ‖ ⋅ ‖ 0 ] (completion of A 0 [ ‖ ⋅ ‖ 0 ] ). In this article, stimulated by physical examples, we introduce the notion of a locally convex quasi C ∗ -normed algebra, aiming at the investigation of A 0 ˜ [ τ ] ; in particular, we study its structure, ∗-representation theory and functional calculus.
Nonlinear Nonhomogeneous Elliptic Problems
2019
We consider nonlinear elliptic equations driven by a nonhomogeneous differential operator plus an indefinite potential. The boundary condition is either Dirichlet or Robin (including as a special case the Neumann problem). First we present the corresponding regularity theory (up to the boundary). Then we develop the nonlinear maximum principle and present some important nonlinear strong comparison principles. Subsequently we see how these results together with variational methods, truncation and perturbation techniques, and Morse theory (critical groups) can be used to analyze different classes of elliptic equations. Special attention is given to (p, 2)-equations (these are equations driven…
Maximal Operators with Respect to the Numerical Range
2018
Let $\mathfrak{n}$ be a nonempty, proper, convex subset of $\mathbb{C}$. The $\mathfrak{n}$-maximal operators are defined as the operators having numerical ranges in $\mathfrak{n}$ and are maximal with this property. Typical examples of these are the maximal symmetric (or accretive or dissipative) operators, the associated to some sesquilinear forms (for instance, to closed sectorial forms), and the generators of some strongly continuous semi-groups of bounded operators. In this paper the $\mathfrak{n}$-maximal operators are studied and some characterizations of these in terms of the resolvent set are given.
Measuring diversity. A review and an empirical analysis
2021
Abstract Maximum diversity problems arise in many practical settings from facility location to social networks, and constitute an important class of NP-hard problems in combinatorial optimization. There has been a growing interest in these problems in recent years, and different mathematical programming models have been proposed to capture the notion of diversity. They basically consist of selecting a subset of elements of a given set in such a way that a measure based on their pairwise distances is maximized to achieve dispersion or representativeness. In this paper, we perform an exhaustive comparison of four mathematical models to achieve diversity over the public domain library MDPLIB, …
Two-dimensional filters for structured text
1997
The paper introduces a method for defining filters for structured text. In the method, the text structure is originally defined by a grammar consisting of a set of productions. To describe the information interests, a two-dimensional template is first created interactively from the grammar to show the structure of a set of textual elements, at a chosen level of detail. The template depicts the hierarchical structure of the elements and indicates also optionality, alternatives, and iteration in the structure. Then, the template is filled by constraints and annotations. The constraints allow giving conditions to the content of parts, to the position of parts in an ordered set of parts, and to…
Firefly algorithm based upon slicing structure encoding for unequal facility layout problem
2019
Finding the locations of departments or machines in a workspace is classified as a Facility Layout Problem. Good placement of departments has a relevant influence on manufacturing costs, work in process, lead times and production efficiency. This paper analyses the problem of allocating departments with restrictions in terms of unequal area and rectangular shape within a facility, in order to minimize the sum of material handling costs taking into account the satisfaction of the aspect ratio requested. In particular, we propose for the first time a Firefly Algorithm based on the slicing structure encoding. The proposed method was tested comparing the results obtained from other authors on t…
A Unified Approach to Portfolio Optimization with Linear Transaction Costs
2004
In this paper we study the continuous time optimal portfolio selection problem for an investor with a finite horizon who maximizes expected utility of terminal wealth and faces transaction costs in the capital market. It is well known that, depending on a particular structure of transaction costs, such a problem is formulated and solved within either stochastic singular control or stochastic impulse control framework. In this paper we propose a unified framework, which generalizes the contemporary approaches and is capable to deal with any problem where transaction costs are a linear/piecewise-linear function of the volume of trade. We also discuss some methods for solving numerically the p…