Search results for "extensions"
showing 10 items of 35 documents
QoS Support for Time-Constrained Multimedia Communications in IEEE 802.11 WLANs: A Performance Evaluation
2005
During the past few years, we have been witnessing the massive deployment of IEEE 802.11 wireless LANs. Even though the widespread deployment of such wireless LANs, many studies are still underway aiming to design and develop simple yet effective QoS mechanisms for supporting time-constrained services over such platforms. In this paper, we first overview five different QoS mechanisms recently introduced in the literature as well as the upcoming IEEE 802.11e (EDCA) standard. We then carry out a comparative performance evaluation of all the QoS mechanisms. We focus our study on the effectiveness of the various QoS mechanisms for supporting time-constrained services.
QoS Mechanisms for IEEE 802.11 Wireless LANs
2004
Currently the Internet provides users with access to information across the world using IP technology. Until now most access points to the Internet have been fixed stations at given locations, but with increasing sales of mobile devices, mobility has become a major trend. Therefore, the Internet is becoming more and more heterogeneous due to the recent explosion of wireless networks. The IEEE 802.11 wireless LAN (WLAN) is the most widely used WLAN standard nowadays. Currently the IEEE 802.11 standard specifies an over-the-air interface between wireless devices. However, QoS services over this technology are still being defined aiming to provide support to multiple applications. Thus, a larg…
Brand extension: the moderating role of the category to which the brand extension is found
2008
PurposeThe objective of this paper is to evaluate brand extension from a consumer consumption perspective. The most relevant entity becomes both the product and the choice vector. This provides a different aspect of the heterogeneity as it concerns brand extension.Design/methodology/approachNestlé was selected as the brand to be studied and two qualitative studies were carried out on students based on open‐ended interviews. After a pre‐test, two groups of 400 students were selected. The first group was exposed to the diet biscuits in the context of “nibbling” and the second group exposed to the lip applications in the context “protecting my lips”.FindingsThe results confirm the importance o…
Optimal Extensions of Conformal Mappings from the Unit Disk to Cardioid-Type Domains
2019
AbstractThe conformal mapping $$f(z)=(z+1)^2 $$ f ( z ) = ( z + 1 ) 2 from $${\mathbb {D}}$$ D onto the standard cardioid has a homeomorphic extension of finite distortion to entire $${\mathbb {R}}^2 .$$ R 2 . We study the optimal regularity of such extensions, in terms of the integrability degree of the distortion and of the derivatives, and these for the inverse. We generalize all outcomes to the case of conformal mappings from $${\mathbb {D}}$$ D onto cardioid-type domains.
Morrey–Sobolev Extension Domains
2017
We show that every uniform domain of R n with n ≥ 2 is a Morrey-Sobolev W 1, p-extension domain for all p ∈ [1, n), and moreover, that this result is essentially best possible for each p ∈ [1, n) in the sense that, given a simply connected planar domain or a domain of R n with n ≥ 3 that is quasiconformal equivalent to a uniform domain, if it is a W 1, p-extension domain, then it must be uniform. peerReviewed
Observational constraints on decoupled hidden sectors
2016
We consider an extension of the Standard Model with a singlet sector consisting of a real (pseudo)scalar and a Dirac fermion coupled with the Standard Model only via the scalar portal. We assume that the portal coupling is weak enough for the singlet sector not to thermalize with the Standard Model allowing the production of singlet particles via the freeze-in mechanism. If the singlet sector interacts with itself sufficiently strongly, it may thermalize within itself, resulting in dark matter abundance determined by the freeze-out mechanism operating within the singlet sector. We investigate this scenario in detail. In particular, we show that requiring the absence of inflationary isocurva…
Reheating the Standard Model from a hidden sector
2016
We consider a scenario where the inflaton decays to a hidden sector thermally decoupled from the visible Standard Model sector. A tiny portal coupling between the hidden and the visible sectors later heats the visible sector so that the Standard Model degrees of freedom come to dominate the energy density of the Universe before Big Bang Nucleosynthesis. We find that this scenario is viable, although obtaining the correct dark matter abundance and retaining successful Big Bang Nucleosynthesis is not obvious. We also show that the isocurvature perturbations constituted by a primordial Higgs condensate are not problematic for the viability of the scenario.
Effects of triplet Higgs bosons in long baseline neutrino experiments
2018
The triplet scalars $(\Delta=\Delta^{++},\Delta^{+},\Delta^{0})$, utilized in the so-called Type-II seesaw model to explain the lightness of neutrinos, would generate nonstandard interactions (NSI) for neutrino propagating in matter. We investigate the prospects to probe these interactions in long baseline neutrino oscillation experiments. We analyze the upper bounds that the proposed DUNE experiment might set on the nonstandard parameters and numerically derive upper bounds, as function of the lightest neutrino mass, on the ratio the mass $M_\Delta$ of the triplet scalars and strength $|\lambda_\phi|$ of the coupling $\phi\phi\Delta$ of the triplet $\Delta$ and conventional Higgs doublet $…
Baryogenesis in the two doublet and inert singlet extension of the Standard Model
2016
We investigate an extension of the Standard Model containing two Higgs doublets and a singlet scalar field (2HDSM). We show that the model can have a strongly first-order phase transition and give rise to the observed baryon asymmetry of the Universe, consistent with all experimental constraints. In particular, the constraints from the electron and neutron electric dipole moments are less constraining here than in pure two-Higgs-doublet model (2HDM). The two-step, first-order transition in 2HDSM, induced by the singlet field, may lead to strong supercooling and low nucleation temperatures in comparison with the critical temperature, $T_n \ll T_c$, which can significantly alter the usual pha…
Nonperturbative effective model for the Higgs sector of the standard model
2010
A nonperturbative effective model is derived for the Higgs sector of the Standard Model which is described by a simple scalar theory. The renormalized couplings are determined by the derivatives of the Gaussian effective potential that are known to be the sum of infinite bubble graphs contributing to the vertex functions. A good agreement has been found with strong coupling lattice simulations when a comparison can be made.