Search results for " function"
showing 10 items of 9395 documents
On the Fidelity of IEEE 802.11 commercial cards
2006
The IEEE 802.11 D CF protocol is known to be fair in terms of long-term resource repartition among the contending stations. However, when considering real scenarios, where commercial 802.11 cards interact, very unpredictable as well as sometimes surprising behaviors emerge. Motivation of this paper is to investigate the reasons of the very evident disagreement between the theoretical IEEE 802.11 DCF protocol models and its practical implementations. Inparticular, we try to characterize the card behavior not only in terms of perceived throughput, but also in terms of low-level channel access operations. In fact, the simple throughput analysis does not allow to identify what affecting paramet…
Incipient damage identification through characteristics of the analytical signal response
2008
The analytical signal is a complex representation of a time domain signal: the real part is the time domain signal itself, while the imaginary part is its Hilbert transform. It has been observed that damage, even at a very low level, yields clearly detectable variations of analytical signal quantities such as phase and instantaneous frequency. This observation can represent a step toward a quick and effective tool to recognize the presence of incipient damage where other frequency-based techniques fail. In this paper a damage identification procedure based on an adimensional functional of the square of the difference between the characteristics of the analytical theoretical and measured sig…
Algorithm To Calculate Heart Rate By Removing Touch Errors And Algorithm Analysis
2018
Heart rate is one of the important physiological parameter to measure the stability of the health. This study shows analysis of a proposed algorithm to calculate heart rate with miss touch errors to make it more efficient. Android Smart phone with good quality camera has come to reach of common people and has become one of the most necessary and powerful device for today and of course, for future generation. We can use its powerful features to solve or assess heart state monitoring through capturing necessary data in the form of image. Mobile camera has a photo emitting diode and a photo detector. Light source illuminates the tissue and photo-detector calculates the small intensity variatio…
Spectrum cartography using adaptive radial basis functions: Experimental validation
2017
In this paper, we experimentally validate the functionality of a developed algorithm for spectrum cartography using adaptive Gaussian radial basis functions (RBF). The RBF are strategically centered around representative centroid locations in a machine learning context. We assume no prior knowledge about neither the power spectral densities (PSD) of the transmitters nor their locations. Instead, the received signal power at each location is estimated as a linear combination of different RBFs. The weights of the RBFs, their Gaussian decaying parameters and locations are jointly optimized using expectation maximization with a least squares loss function and a quadratic regularizer. The perfor…
Flip angle considerations in (3)helium-MRI.
2000
3Helium-MRI ((3)He-MRI) can be used for analysis of lung function, e. g. dynamic imaging of ventilation and gas diffusion within the lung, assessment of intrapulmonary oxygen concentrations and their time course. During imaging, the irreversible signal loss due to depolarizing radio frequency excitations can be described using the flip angle (FA) alpha. This parameter has to be quantified in order to account for it during quantitative assessment of the (3)helium signal intensity and its temporal development. This technical report reviews two different methods to determine alpha. Limitations and possible error sources of each method are discussed.
Observer-based finite-time fuzzy H∞ control for discrete-time systems with stochastic jumps and time-delays
2014
This paper is concerned with the problem of observer-based finite-time H ∞ control for a family of discrete-time Markovian jump nonlinear systems with time-delays represented by Takagi-Sugeno (T-S) model. The main contribution of this paper is to design an observer-based finite-time H ∞ controller such that the resulting closed-loop system is stochastic finite-time bounded and satisfies a prescribed H ∞ disturbance attenuation level over the given finite-time interval. Sufficient criteria on stochastic finite-time H ∞ stabilization via observer-based fuzzy state feedback are presented for the solvability of the problem, which can be tackled by a feasibility problem in terms of linear matrix…
Multiple-Output Walsh Function Generation for Minimum Orthogonality Error
1978
A hazard-free multiple-output Walsh function generator is presented which requires a minimum amount of hardware and is as fast as the integrated logic family employed for the implementation. However, the main characteristic of the instrument is the optimum performance from the viewpoint of the orthogonality of the function generated, as it is shown by the experimental verifications reported.
The spatial distribution of non-linear effects in multi-photon photoemission from metallic adsorbates on Si(1 1 1)
2001
Multi-photon excitations from thin metallic films on silicon substrates have been observed utilising photoemission electron microscopy. The photoelectrons have been excited by means of high power femtosecond laser pulses with a photon energy below the work function threshold. The strong spatial variations of the non-linear effects became directly visible in electron emission from the adsorbed thin films. Centres of enhanced photoelectron yield, so-called hot spots, were observed on the surfaces of various samples. The multi-photon electron yield of the metallic films (permalloy and lead) depends strongly on the sample topography and the photon polarisation.
Nitrogen interstitial defects in silicon. A quantum mechanical investigation of the structural, electronic and vibrational properties
2019
The vibrational features of eight interstitial nitrogen related defects in silicon have been investigated at the first principles quantum mechanical level by using a periodic supercell approach, a hybrid functionals, an all electron Gaussian type basis set and the Crystal code. The list includes defects that will be indicated as Ni (one N atom forming a bridge between two Si atoms), Ni-Ns (one interstitial and one substitutional N atom linked to the same Si atom), Ni-Ni (two Ni defects linked to the same couple of silicon atoms) and Ni-Sii-Ni (two Ni defects linked to the same interstitial silicon atom). Four 〈0 0 1〉 split interstitial (dumbbell) defects have also been considered, in which …
Reactivity of antitumor coinage metal-based N-heterocyclic carbene complexes with cysteine and selenocysteine protein sites
2021
Abstract The reaction of the antitumor M(I)-bis-N-heterocyclic carbene (M(I)-NHC) complexes, M = Cu, Ag, and Au, with their potential protein binding sites, i.e. cysteine and selenocysteine, was investigated by means of density functional theory approaches. Capped cysteine and selenocysteine were employed to better model the corresponding residues environment within peptide structures. By assuming the neutral or deprotonated form of the side chains of these amino acids and by considering the possible assistance of an external proton donor such as an adjacent acidic residue or the acidic component of the surrounding buffer environment, we devised five possible routes leading to the binding o…