Search results for "WIDTH"
showing 10 items of 690 documents
Channel aggregation with guard-band in D-OFDM based CRNs: Modeling and performance evaluation
2016
Channel aggregation (CA) techniques can offer flexible channel allocation and improve overall system performance in multi-channel cognitive radio networks (CRNs). Although many CA techniques have been proposed and studied, the impact of guard-band on CA for channel access has not been addressed in-depth. In this paper, we study the guard-band allocation mechanisms in discontinuous-orthogonal frequency division multiplexing (D-OFDM) based CRNs, and investigate the impact of guard-band sharing on SU flows when CA is enabled. Continuous time Markov chain (CTMC) based models have been developed in order to investigate the stochastic behavior of PU and SU flows. Based on our mathematical analysi…
<title>Statistical bandwidth allocation for multiservice networks</title>
2002
Multiservice networks will carry di erent kinds of applications in the near future. Bandwidth requirements change rapidly, and the network resource management will play an important role to guarantee the use of the limited resources in the most eAEcient way. We approach the channel capacity allocation problem by developing an SLA (Service Level Agreement) based channel allocation method. In our model, the channel may be wired or wireless, so this method can be adapted in multi-technique networks. The algorithm allocates resources to several di erent service classes via several di erent capacity routes. Service provider perfroms optimization by allocating data rate in such a way that the sat…
Channel capacity of fading channels for differentially encoded transmission
1999
The capacity of flat fading channels when applying differential encoding with noncoherent reception and no channel state information available at the receiver is considered. Numerical results indicate the gains achievable by multiple symbol detection in the case of slowly time-varying channels and provide a comparison between schemes with different potential bandwidth efficiencies.
Einfluß der quellung in aceton auf das kernresonanzspektrum von polyäthylenterephthalat
1971
Die Kernresonanzspektren isotherm kristallisierter Proben von Polyathylenterephthalat wurden vor und nach der Quellung in deuteriertem Aceton als Funktion der Temperatur gemessen. Anschliesend wurde jedes Spektrum in eine breite und eine schmale Komponente zerlegt. Es zeigt sich, das durch die Quellung der Einfrierbereich verbreitert und die Einfriertemperatur erniedrigt wird. Diese Erniedrigung ist von den Kristallisationsbedingungen unabhangig. Die Linienbreite der schmalen Komponente wird durch die Quellung leicht erhoht, was fur eine Zunahme der Kettenverspannung in den nichtkristallinen Bereichen spricht. Das zweite Moment der breiten Komponente wird durch die Quellung erniedrigt. Dara…
High-resolution photoacoustic Raman spectroscopy of gases
1992
A high-resolution photoacoustic Raman spectroscopy experiment is described. The resolution achieved by using two single-mode pulsed lasers is about 0.0054 cm −1 (full width at half maximum intensity). The experiment was tested first on the v 1 /2v 2 bands of CO 2 and gave an increase of at least about one order of magnitude in the signal-to-noise ratio with respect to stimulated Raman spectroscopy at low pressure (ca. 10 Torr ≃ 1.3 kPa). The sensitivity is also demonstrated by the study of the weak hot band v 1 +v 2 −v 2 of CO 2 . In both cases, the experimental line shape is well reproduced by taking into account Doppler and collisional effects. A comparison with CARS spectra was also made
Single-crystal EPR study of the bimetallic ferrimagnetic chain MnCu(EDTA)·6H2O
1993
Abstract A single-crystal EPR study of the bimetallic chain compound MnCu(EDTA)·6H2O is reported. The angular dependence of the linewidth is discussed in relation to the magnetic dipole-dipole interaction, manganese zerofield splitting (ZFS) and copper hyperfine coupling. The calculation of the second moments indicates that ZFS is comparable to the dipolar contribution. The EPR data support the one-dimensional character of the compound.
Overlapped moving windows followed by principal component analysis to extract information from chromatograms and application to classification analys…
2015
Variable generation from chromatograms is conveniently accomplished using unsupervised rather than manual techniques. With unsupervised techniques, there is no need for selecting a few peaks for manual integration and valuable information is quickly and efficiently collected. The generation of variables can be performed by using either peak searching or moving window (MW) strategies. With a MW approach, the peaks are ignored and many variables, only part of them carrying information, are generated. Thus, variable generation by MWs should be followed by data compression to generate the variables to be further used for classification or quantitation purposes. In this work, unsupervised proces…
Optimized Multipactor-Resistant Wedge-Shaped Waveguide Bandpass Filters
2013
[EN] Wedge-shaped waveguides present a certain advantage with respect to rectangular waveguides regarding their resistance to multipactor discharges. In this paper, the optimal configuration for the wedge geometry is investigated based on theoretical results, on a precise multipactor prediction tool, and on previous experience. In addition, design rules are presented, which allow us to achieve for wedge-shaped filters electrical performances comparable to the ones of rectangular waveguide filters, while at the same time improving the multipactor-free power range. As a proof of concept, two three-pole bandpass filters with equivalent electrical characteristic of 150-MHz bandwidth, centered a…
Circular dichroism of magnetically induced transitions for D 2 lines of alkali atoms
2018
In this letter we study magnetic circular dichroism in alkali atoms exhibiting asymmetric behaviour of magnetically induced transitions. The magnetic field induces transitions between hyperfine levels of alkali atoms and in the range of magnetic field, the intensities of these transitions experience significant enhancement. We have inferred a general rule applicable for the D 2 lines of all alkali atoms, that is the transition intensity enhancement is around four times larger for the case of than for excitation for , whereas it is several hundreds of thousand times larger in the case of than that for polarization for . This asymmetric behaviour results in circular dichroism. For experimenta…
On the chromatic number of disk graphs
1998
Colorings of disk graphs arise in the study of the frequency-assignment problem in broadcast networks. Motivated by the observations that the chromatic number of graphs modeling real networks hardly exceeds their clique number, we examine the related properties of the unit disk (UD) graphs and their different generalizations. For all these graphs including the most general class of the double disk (DD) graphs, it is shown that X(G) ≤ c.ω(G) for a constant c. Several coloring algorithms are analyzed for disk graphs, aiming to improve the bounds on X(G). We find that their worst-case performance expressed in the number of used colors is indeed reached in some instances.