Search results for "upper"
showing 10 items of 987 documents
On the performance of hybrid-ARQ with code combining over double rayleigh fading channels
2011
In this paper, we study the performance of hybrid automatic repeat request (HARQ) with code combining (CC) over double Rayleigh channels. This channel can be utilized to model the fading envelope of vehicle-to-vehicle (V2V) channels. We derive analytical solutions for the characteristic quantities of double Rayleigh channels, such as the outage probability, the ergodic capacity, and the bit error probability (BEP). Moreover, we study the performance of HARQ with CC. Our analysis focuses on information theoretic aspects of HARQ with CC. closed-form analytical approximations are derived for the e-outage capacity, the average number of transmissions, and the average transmission rate of HARQ w…
Do we need metamodels AND ontologies for engineering platforms?
2006
In this paper we show how the joint use of metamodeling and ontologies allows to describe domain knowledge for a complex domain. Ontologies are used as stabilized descriptions of a business domain while metamodels allow a fine description of the domain (to be constructed in the initial phases of modeling). We propose to use an ontology for early categorization, i.e., as a "natural" complement of the formal system that is induced by the metamodel.
Exploring twitter for csr disclosure: influence of ceo and firm characteristics in latin american companies
2018
Social networks, which are characterised by accessibility and interactivity, offer great potential for dialogue between companies and stakeholders, for example as platforms for publishing information on aspects of corporate social responsibility (CSR). In this paper, we use a synthetic index to analyse levels of CSR disclosure via Twitter, and identify explanatory variables of this disclosure by studying the demographic characteristics of the Chief Executive Officer (CEO) and of the company. This synthetic index was based on data for 93 companies located in the four countries of the Pacific Alliance (Chile, Colombia, Mexico, and Peru), using categories based on the 2016 Global Reporting Ini…
$MC$-hypercentral groups
2007
This paper is devoted to the imposition of some chain conditions on groups having a generalized central series. It is also given a characterization of MC-groups with finite abelian section rank: such class of groups is a suitable enlargement of the class of FC-groups. Mathematics Subject Classification: 20F24; 20F14
Temperature and pressure dependence of phase separation of trans-decahydronaphthalene/polystyrene solution
2004
Abstract The cloud-point temperatures (Tcl’s) of trans-decahydronaphthalene (TD)/polystyrene (PS, Mw=270 kg/mol) solutions were determined by light scattering measurements over a range of temperatures (1–16 °C), pressures (100–900 bar), and compositions (4.2–21.6 vol% polymer). The system phase separates upon cooling and the Tcl was found to increase with the rising pressure for the constant composition. In the absence of special effects this finding indicates positive excess volumes. The special attention was paid to the demixing temperatures as a function of the pressure for the different polymer solutions and the plots in the T-volume fraction plane and P-volume fraction plane. The cloud…
The Efficiency of Polymer Fractionation at Lower Critical Solution Temperatures
1978
The efficiency of a single fractionation step (i.e. of the partition of a given polymer sample between the coexisting phases which form when its solution demixes) is governed by the variation of the mass ratio of the individual P-mers with chain length. These dependences have been measured for the system dimethoxymethane/diethylether/ polystyrene which exhibits lower critical solution temperatures by means of the Baker-Williams method and by means of g.p.c. Their comparison with the results of previous investigation on systems showing upper critical solution temperatures reveals no thermodynamic differences in the aptitude of upper and lower critical solution temperatures for fractionation …
HOWERD: A Hidden Markov Model for Automatic OWL-ERD Alignment
2016
The HOWERD model for estimating the most likely alignment between an OWL ontology and an Entity Relation Diagram (ERD) is presented. Automatic alignment between relational schema and ontology represents a big challenge in Semantic Web research due to the different expressiveness of these representations. A relational schema is less expressive than the ontology; this is a non trivial problem when accessing data via an ontology and for ontology storing by means of a relational schema. Existent alignment methodologies fail in loosing some contents of the involved representations because the ontology captures more semantic information, and several elements are left unaligned. HOWERD relies on a…
Reproducing pairs of measurable functions
2017
We analyze the notion of reproducing pair of weakly measurable functions, which generalizes that of continuous frame. We show, in particular, that each reproducing pair generates two Hilbert spaces, conjugate dual to each other. Several examples, both discrete and continuous, are presented.
Lower bound limit analysis by bem: Convex optimization problem and incremental approach
2013
Abstract The lower bound limit approach of the classical plasticity theory is rephrased using the Multidomain Symmetric Galerkin Boundary Element Method, under conditions of plane and initial strains, ideal plasticity and associated flow rule. The new formulation couples a multidomain procedure with nonlinear programming techniques and defines the self-equilibrium stress field by an equation involving all the substructures (bem-elements) of the discretized system. The analysis is performed in a canonical form as a convex optimization problem with quadratic constraints, in terms of discrete variables, and implemented using the Karnak.sGbem code coupled with the optimization toolbox by MatLab…
Limits on point-like sources of ultra-high-energy neutrinos with the Pierre Auger Observatory
2019
With the Surface Detector array (SD) of the Pierre Auger Observatory we can detect neutrinos with energy between 1017 eV and 1020 eV from point-like sources across the sky, from close to the Southern Celestial Pole up to 60 in declination, with peak sensitivities at declinations around ∼-53 and ∼+55, and an unmatched sensitivity for arrival directions in the Northern hemisphere. A search has been performed for highly-inclined air showers induced by neutrinos of all flavours with no candidate events found in data taken between 1 Jan 2004 and 31 Aug 2018. Upper limits on the neutrino flux from point-like steady sources have been derived as a function of source declination. An unrivaled sensit…