Search results for "WBAN"
showing 10 items of 43 documents
Transverse chemical interface detection with coherent anti-Stokes Raman scattering microscopy
2011
International audience; Transverse "chemical" interfaces are revealed with a conventional two beam narrowband coherent anti-Stokes Raman scattering microscopy setup in a collinear configuration. The exciting "pump" and "Stokes" beams are focused on the sample in two opposite directions. The subtraction of the two generated anti-Stokes signals gives rise to a signal that is directly proportional to the pure Raman spectrum of the resonant medium. This property is used to highlight an interface between glass and N,N-dimethylformamide (DMF) and recover the pure Raman spectrum of DMF around its 1408 cm−1 vibrational band.
BEP analysis of M-ary PSK modulation schemes over double Rice fading channels with EGC
2010
In this article, the performance of M-ary phase shift keying (PSK) modulation schemes over mobile-to-mobile (M2M) fading channels with equal gain combining (EGC) in cooperative networks is analyzed. Narrowband M2M fading channels under line-of-sight (LOS) propagation conditions are modeled as double Rice processes. A dual-hop amplify-and-forward relay network, where LOS components can exist in the transmission links between the source mobile station and the destination mobile station via K mobile relays, is studied. Here, the average bit error probability (BEP) is utilized to evaluate the performance of Mary PSK modulation schemes. A simple analytical approximation for the average BEP of M-…
A device for multimodal imaging of skin
2013
A compact prototype device for diagnostic imaging of skin has been developed and tested. Polarized LED light at several spectral regions is used for illumination, and round skin spot of diameter 30mm is imaged by a CMOS sensor via crossoriented polarizing filter. Four consecutive imaging series are performed: (1) RGB image at white LED illumination for revealing subcutaneous structures; (2) four spectral images at narrowband LED illumination (450nm, 540nm, 660nm, 940nm) for mapping of the main skin chromophores; (3) video-imaging under green LED illumination for mapping of skin blood perfusion; (4) autofluorescence video-imaging under UV (365nm) LED irradiation for mapping of the skin fluor…
A narrowband MIMO car-to-car channel model based on the geometrical street scattering model
2012
In this paper, we model a narrowband multiple-input multiple-output (MIMO) car-to-car (C2C) channel model based on the geometrical street scattering model. Starting from the geometrical model, a MIMO reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS) and non-LOS (NLOS) propagation environments. In the proposed channel model, an infinite number of scatterers are uniformly distributed in rectangular grids located on both sides of the street. Analytical solutions are presented for the three-dimensional (3D) space-time cross-correlation function (CCF), the temporal autocorrelation function (ACF), and the two-dimensional (2D) space CCF. An …
Oligonucleotide-Hybridization Fiber-Optic Biosensor using a Narrow Bandwidth Long Period Grating
2017
Nanometric narrowband Long Period Gratings (LPG) are investigated for the implementation of improved fiber optic biosensors. The reduction of more than one order of magnitude in the linewidth of the LPG with respect standard LPG at 1500 nm, leads to the improvement of the resolution of the sensor. By selecting the proper fabrication parameters (high numerical aperture, relatively high order mode and large length), LPGs with a 3-dB bandwidth of 1.5 nm were fabricated. The sensitivity of the LPG as a refractometer was calculated, and experimentally characterized in detail. In particular, the LP0,17 and LP0,18 resonances were investigated, in order to select the most suitable one for the bioex…
Remote photoplethysmography for skin perfusion monitoring using narrowband illumination
2019
The purpose of this study was to determine potential of remote photoplethysmography for skin perfusion monitoring, using 540 nm narrowband and 530 nm broadband illuminations. The alterations of cutaneous circulation were produced by topical skin heating protocol. The setup comprises of 530 nm LED light source and two identical cameras operated simultaneously: one equipped with narrowband optical filter (CWL=540nm), and another without filter. Results demonstrate the typical heating test response curve- comprising first peak, nadir and plato phase, which were significantly different in narrowband and broadband illumination. It was concluded that selection of optimal light source parameters i…
Structure of the Accretion Disk in the Lensed Quasar Q2237+0305 from Multi-Epoch and Multi-Wavelength Narrow Band Photometry
2015
We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305, independent of the component velocities. These estimates are based on six epochs of multi-wavelength narrowband images from the Nordic Optical Telescope. For each pair of lensed images and each photometric band, we determine the microlensing amplitude and chromaticity using pre-existing mid-IR photometry to define the baseline for no microlensing magnification. A statistical comparison of the combined microlensing data (6 epochs $\times$ 5 narrow bands $\times$ 6 image pairs) with simulations based on microlensing magnification maps gives Bayesian estimates for the ha…
Lossless equalization of frequency combs
2008
Frequency combs obtained by sinusoidal phase modulation of narrow-band continuous-wave lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not at. In this Letter, we propose a general and eficient approach to achieve at frequency combs with tunable bandwidth. The idea is based on a two-step process. First, eficient generation of a train with temporal at-top-pulse profile is required. Second, we use large parabolic phase modulation in every train period in order to map the temporal intensity shape into the spectral domain. In this way, the resulting spectral envelope is at and the size is tunable with the chirping rate. Two d…
The role of nonlinear optical absorption in narrowband difference-frequency terahertz-wave generation
2010
We present a general analysis of the influence of nonlinear optical absorption on terahertz generation via optical difference frequency generation, when reaching for the quantum conversion efficiency limit. By casting the equations governing the process in a suitably normalized form, including either two-photon- or three-photon-absorption terms, we have been able to plot universal charts for phase matched optical-to-terahertz conversion for different values of the nonlinear absorption coefficients. We apply our analysis to some experiments reported to date, in order to understand to what extent multiphoton absorption could have played a role and also to predict the maximum achievable conver…
Channel estimation and transmit power control in wireless body area networks
2015
Wireless body area networks have recently received much attention because of their application to assisted living and remote patient monitoring. For these applications, energy minimisation is a critical issue since, in many cases, batteries cannot be easily replaced or recharged. Reducing energy expenditure by avoiding unnecessary high transmission power and minimising frame retransmissions is therefore crucial. In this study, a transmit power control scheme suitable for IEEE 802.15.6 networks operating in beacon mode with superframe boundaries is proposed. The transmission power is modulated, frame-by-frame, according to a run-time estimation of the channel conditions. Power measurements u…