Search results for "LESS"
showing 10 items of 2452 documents
Making WiFi work in multi-hop topologies: Automatic negotiation and allocation of airtime
2015
We propose a solution for mitigating the performance impairments of CSMA/CA protocols in multi-hop topologies based on the dynamic adaptation of the contention process experienced by nodes in a wireless network. A distributed protocol is used to negotiate the channel airtime for a node as a function of the traffic requirements of its neighbourhood, taking into account bandwidth reserved for the control operations. A mechanism is provided for a node to tune its contention window depending on its allocated airtime. Different from previous schemes, a node's contention window is fixed in size unless the traffic requirements of its neighbourhood change. The scheme is implemented on legacy commer…
Power consumption analysis for mobile stations in hybrid relay-assisted wireless networks
2010
While Internet access using mobile or wireless technologies has become ubiquitous these days, the energy consumption aspect of such connections has not been studied in-depth yet. In this paper, a hybrid wireless network, which consists of a cellular component and a relay-assisted ad hoc component, is studied focusing on energy consumption by mobile stations with respect to the amount of data communicated and achieved battery lifetime. Four alternative paths are considered, including both pure cellular and hybrid ad hoc/cellular links for uplink and downlink traffic. The effects of each alternative connection on energy consumption of the involved mobile stations are analyzed in terms of the …
On building an infrastructure for mobile and wireless systems
2002
Over the last few years, there have been at least two dramatic changes in the way computers are used. The first has its origin in the fact that computers have become more and more connected to each other. The second was triggered by the increasing miniaturization and affordability of hardware components and power supplies, together with the development of wireless communication paths. These two trends combined have allowed the development of powerful, yet comparatively low-priced, portable computers. In spite of these changes, little attention has been given to reaching a common consensus and to the development of a strong infrastructure in this area.
A Small Scale Resonant Coupling Wireless Power Transmission Prototype for EV Applications
2012
In this paper a low cost prototype of wireless power transfer system based on resonant coupling is presented. The system here proposed can be useful for electric vehicle (EV) battery charging systems: as a matter of fact, it consists mainly of two copper wire coils or windings, placed one in front of the other on the same axis. The inductor coil can easily be placed under the road surface (in a parking), while the other (the receiver coil) in the lower side of the vehicle. By exploiting the coils resonance coupling effect, electric energy can be transferred from the inductor coil to the receiver in order to charge the batteries. Low cost experimental tests carried out at DIEETCAM – Universi…
Sentir lo indecible. Sentido, sin sentido y carencia de sentido en el Tractatus de Wittgenstein
2008
Este artículo analiza la concepción wittgensteiniana del sin sentido y, contra las interpretaciones resolutas, defiende que, bajo la influencia quizás de Mauthner y Weininger, el autor del Tractutus consideró los sin sentidos ontológicos y éticos correctos como cercanos a las proposiciones tautológicas carentes de sentido. This article analyses Wittgenstein�s conception of nonsense and, against resolute interpretations, defends that, perhaps influenced by Mauthner and Weininger, the Tractatus author conceived corrects ontological and ethical nonsenses like nearly to tautological senseless.
On the mechanisms involved in the tensile strength of a dissimilar Ti6Al4V/316L laser welded assembly
2021
International audience; The aim of the present work is to analyze the thermomechanical behavior of dissimilar laser seams by means of FE modeling. The case of a Ti6Al4V/316L assembly with vanadium insert was considered. Effective mechanical properties of the main materials and cords were first estimated from NHT measurements. Modeling of the double pass laser welding process was performed first by considering shrinking of the two weld seams during manufacturing, to get the residual stress state in the welded assembly. Modeling of the tensile test was performed in a second step to study the assembly behavior during loading. In these modeling results, the mesh was the cross-section of the mic…
Evaluation of building heating loads with dimensional analysis: Application of the Buckingham π theorem
2017
Abstract A detailed assessment of building energy performance requires a large amount of input data concerning building typology, environmental conditions, envelope thermophysical properties, geometry, control strategies, and several other parameters. Notwithstanding, the use of specialized software tools poses many challenges in regards to the retrieval of reliable and detailed information, setting a steep learning curve for engineers and energy managers. To speed up the preliminary assessment phase, it might be more convenient to resort to a simplified model that allows the evaluation of heating energy demand with a good level of accuracy and without excessive computational cost or user e…
Estimating the temperature evolution of foodstuffs during freezing with a 3D meshless numerical method
2015
Abstract Freezing processes are characterised by sharp changes in specific heat capacity and thermal conductivity for temperatures close to the freezing point. This leads to strong nonlinearities in the governing PDE that may be difficult to resolve using traditional numerical methods. In this work we present a meshless numerical method, based on a local Hermite radial basis function collocation approach in finite differencing mode, to allow the solution of freezing problems. By introducing a Kirchhoff transformation and solving the governing equations in Kirchhoff space, the strength of nonlinearity is reduced while preserving the structure of the heat equation. In combination with the hig…
Wireless power transfer system stability analysis for E-bikes application
2019
The present work reports the stability analysis of an Inductive Coupled Power Transfer (ICPT) System coupled to an electrical bike. The study has focused on two coupled coils with circular geometry and vertical disposition. In the first part of the work, the theoretical aspects related to the stability of wireless power systems are handled. In the second part, performing several simulations, varying the features of the considered configuration, the stability is looked for. In order to perform this process, the Ansys Maxwell software has been used, performing 3D simulations.
Editorial: Special Issue on "5G Workshop on Networks, Services and Applications" : topics from the 1st Joint Workshop between Center for TeleInFrastr…
2010
Published version of an article in Wireless Personal Communications, 57(3), 313-316. Also available from the publisher at http://dx.doi.org/10.1007/s11277-010-0068-7 The first joint workshop between Center for TeleInFrastruktur (CTIF), Denmark and Center for Wireless Innovation (CWI), Norway, was held in Aalborg, Denmark on October 8, 2009, focusing on yet undefined term, "5G mobile networks". This Special Issue features eleven selected papers based on networks, services and applications aspects of 5G.