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Institution

Philips

CompanyVantaa, Finland
About: Philips is a company organization based out in Vantaa, Finland. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 68260 authors who have published 99663 publications receiving 1882329 citations. The organization is also known as: Koninklijke Philips Electronics N.V. & Royal Philips Electronics.


Papers
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Proceedings ArticleDOI
01 Apr 2007
TL;DR: This paper introduces a novel cognitive MAC (C-MAC) protocol for distributed multi-channel wireless networks that is able to effectively deal with the dynamics of resource availability due to primary users and mitigate the effects of distributed quiet periods utilized for primary user signal detection.
Abstract: A number of algorithmic and protocol assumptions taken for granted in the design of existing wireless communication technologies need to be revisited in extending their scope to the new cognitive radio (CR) paradigm. The fact that channel availability can rapidly change over time and the need for coordinated quiet periods in order to quickly and robustly detect the presence of incumbents, are just some of the examples of the unique challenges in protocol and algorithm design for CR networks and, in particular, in the medium access control (MAC) layer. With this in mind, in this paper we introduce a novel cognitive MAC (C-MAC) protocol for distributed multi-channel wireless networks. C-MAC operates over multiple channels, and hence is able to effectively deal with, among other things, the dynamics of resource availability due to primary users and mitigate the effects of distributed quiet periods utilized for primary user signal detection. In C-MAC, each channel is logically divided into recurring superframes which, in turn, include a slotted beaconing period (BP) where nodes exchange information and negotiate channel usage. Each node transmits a beacon in a designated beacon slot during the BP, which helps in dealing with hidden nodes, medium reservations, and mobility. For coordination amongst nodes in different channels, a rendezvous channel (RC) is employed that is decided dynamically and in a totally distributed fashion. Among other things, the RC is used to support network-wide multicast and broadcast which are often neglected in existing multi-channel MAC protocols. We present promising performance results of C- MAC. We also describe our efforts to implement features of C- MAC in a real CR prototype with Atheros chipset, which currently includes the spectrum sensing module and preliminary features of C-MAC.

449 citations

Journal ArticleDOI
M.J. Powell1
TL;DR: In this paper, the basic physics underlying the operation and key performance issues of amorphous-silicon thin-film transistors are discussed, and the transistors also show longer time threshold voltage shifts due to two distinct mechanisms: charge trapping in the silicon nitride gate insulator and metastable dangling bond state creation.
Abstract: The basic physics underlying the operation and key performance issues of amorphous-silicon thin-film transistors (TFTs) are discussed. The static transistor characteristics are determined by the localized electronic states that occur in the bandgap of the amorphous silicon. The deep states, mostly consisting of Si dangling bonds, determine the threshold voltage, and the conduction band-tail states determine the field-effect mobility. The finite capture and emission times of the deep localized states lead to a dynamic transistor characteristic that can be described by a time-dependent threshold voltage. The transistors also show longer time threshold voltage shifts due to two other distinct mechanisms: charge trapping in the silicon nitride gate insulator and metastable dangling bond state creation in the amorphous silicon. These two mechanisms show characteristically different bias, temperature, and time dependencies of the threshold voltage shift. Illumination of a TFT causes the generation of electron-hole pairs in the space-charge region leading to a steady-state equal flux of electrons and holes and a reduction in the band-bending. In most applications, the photosensitivity should be minimized. The uniformity of large arrays of transistors for display applications is excellent, with variations in the threshold voltage of 0.5-1.0 V. >

449 citations

Journal ArticleDOI
TL;DR: Multiparametric MR imaging of the prostate at 3 T enables tumor detection, with reasonable sensitivity and specificity values, and Generalized estimating equations (GEEs) provided significant independent and additive predictive value when GEEs were used.
Abstract: Combined use of anatomic (T2-weighted MR imaging) and functional (MR spectroscopy and dynamic contrast material–enhanced MR imaging) modalities improves the performance of MR imaging for prostate tumor detection.

447 citations

Journal ArticleDOI
A. Van Wieringen1, N. Warmoltz1
TL;DR: In this paper, a mass spectrometer examination of the permeability of the elements silicon and germanium to the gases hydrogen and helium has been carried out in the temperature range 967-1207°C for silicon and 766-930°C with respect to helium.

446 citations


Authors

Showing all 68268 results

NameH-indexPapersCitations
Mark Raymond Adams1471187135038
Dario R. Alessi13635474753
Mohammad Khaja Nazeeruddin12964685630
Sanjay Kumar120205282620
Mark W. Dewhirst11679757525
Carl G. Figdor11656652145
Mathias Fink11690051759
David B. Solit11446952340
Giulio Tononi11451158519
Jie Wu112153756708
Claire M. Fraser10835276292
Michael F. Berger10754052426
Nikolaus Schultz106297120240
Rolf Müller10490550027
Warren J. Manning10260638781
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20235
202239
2021898
20201,428
20191,665
20181,378