Search results for "Operation"
showing 10 items of 2969 documents
ChemInform Abstract: Exploring the Properties of MTO4Compounds Using High-Pressure Powder X-Ray Diffraction
2015
Several ternary oxides with industrial applications, but also interesting for basic research, have been studied recently at room temperature under high-pressure conditions using synchrotron powder x-ray diffraction. In this article, part of these experiments will be summarized. The studied materials include zircon-type vanadates and scheelite-type tungstates as well as other oxides related to them. Several pressure-induced structural phase transitions that take place in these compounds under compression will be here described. In addition, the determination of the crystal structure of the high-pressure phases will be discussed. The reported studies have also allowed the accurate determinati…
Categorical Modeling Method of Intelligent WorkFlow
2018
A category as well as a model is a mixture of graphical information and algebraic operations. Therefore, category language seems to be the most general to describe the models. It can provide us with the features that must characterize both the DSL language and the Modeling Method concept.
Il Consiglio europeo e la crisi del debito sovrano
2013
Il lavoro si occupa del ruolo svolto dal Consiglio europeo nel coordinamento delle politiche economiche degli Stati membri dell'UE di fronte alla crisi del debito sovrano, occupandosi in particolare di due problemi: da un lato quello della natura giuridica del Consiglio europeo e, da un altro lato, quello dei riflessi prodotti dall'intervento di quest'ultimo sul modo di funzionamento della cooperazione economica tra gli Stati membri dell'Unione.
Modelling mode choice for freight transport using advanced choice experiments
2015
Abstract In this paper we use advanced choice modelling techniques to analyse demand for freight transport in a context of modal choice. To this end, a stated preference (SP) survey was conducted in order to estimate freight shipper preferences for the main attributes that define the service offered by the different transport modes. From a methodological point of view, we focus on two critical issues in the construction of efficient choice experiments. Firstly, in obtaining good quality prior information about the parameters; and secondly, in the improved quality of the experimental data by tailoring a specific efficient design for every respondent in the sample. With these data, different …
From fuzzy metric spaces to modular metric spaces: a fixed point approach
2017
We propose an intuitive theorem which uses some concepts of auxiliary functions for establishing existence and uniqueness of the fixed point of a self-mapping. First we work in the setting of fuzzy metric spaces in the sense of George and Veeramani, then we deduce some consequences in modular metric spaces. Finally, a sample homotopy result is derived making use of the main theorem.
An exact method for graph coloring
2006
International audience; We are interested in the graph coloring problem. We propose an exact method based on a linear-decomposition of the graph. The complexity of this method is exponential according to the linearwidth of the entry graph, but linear according to its number of vertices. We present some experiments performed on literature instances, among which COLOR02 library instances. Our method is useful to solve more quickly than other exact algorithms instances with small linearwidth, such as mug graphs. Moreover, our algorithms are the first to our knowledge to solve the COLOR02 instance 4-Inser_3 with an exact method.
The Steiner Traveling Salesman Problem and its extensions
2019
Abstract This paper considers the Steiner Traveling Salesman Problem, an extension of the classical Traveling Salesman Problem on an incomplete graph where not all vertices have demand. Some extensions including several depots or location decisions are introduced, modeled and solved. A compact integer linear programming formulation is proposed for each problem, where the routes are represented with two-index decision variables, and parity conditions are modeled using cocircuit inequalities. Exact branch-and-cut algorithms are developed for all formulations. Computational results obtained confirm the good performance of the algorithms. Instances with up to 500 vertices are solved optimally.
An elementary proof of Hilbertʼs theorem on ternary quartics
2012
Abstract In 1888, Hilbert proved that every nonnegative quartic form f = f ( x , y , z ) with real coefficients is a sum of three squares of quadratic forms. His proof was ahead of its time and used advanced methods from topology and algebraic geometry. Up to now, no elementary proof is known. Here we present a completely new approach. Although our proof is not easy, it uses only elementary techniques. As a by-product, it gives information on the number of representations f = p 1 2 + p 2 2 + p 3 2 of f up to orthogonal equivalence. We show that this number is 8 for generically chosen f, and that it is 4 when f is chosen generically with a real zero. Although these facts were known, there wa…
Graph connectivity and monadic NP
2002
Ehrenfeucht games are a useful tool in proving that certain properties of finite structures are not expressible by formulas of a certain type. In this paper a new method is introduced that allows the extension of a local winning strategy for Duplicator, one of the two players in Ehrenfeucht games, to a global winning strategy. As an application it is shown that graph connectivity cannot be expressed by existential second-order formulas, where the second-order quantification is restricted to unary relations (monadic NP), even, in the presence of a built-in linear order. As a second application it is stated, that, on the other hand, the presence of a linear order increases the power of monadi…
Using Search Algorithms for Modeling Economic Processes
2013
Abstract Economic issues are placed in formal practice, when is desired a modelling of the economic process, a manufacturing process, a device, etc. Each share of that economic process is denoted by a, b, c, d, these actions with defined time periods and action pairs are formed strings of the form, ab * cab * bc ., ab, bb, bc. so for them there are no other restrictions. If the graph is viewed as a system image, nodes representing components, then an immediate interpretation of an arc (xi, xj) are the component xi that is said to directly influence component xj. If nodes have the significance of possible states of a system when a spring (xi.xj) means that, the system can jump from state xi …