Search results for "Telecommunication"

Status of the EPIC thin and medium filters on-board XMM-Newton after more than 10 years of operation II: analysis of in-flight data

2013

After more than ten years of operation of the EPIC camera on board the X-ray observatory XMM-Newton we have reviewed the status of its thin and medium filters by performing both analysis of data collected in-flight and laboratory measurements on on-ground back-up filters. We have investigated the status of the EPIC thin and medium filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission of the filters. We both investigated repeated observations of single optically bright targets and performed a statistical analysis of the extent of loading versus visual magnitude at different epochs. We report the results of these …

Implementation of a two stage fully-blind self-adapted spectrum sensing algorithm

2017

In this paper, an experimental validation of a combined two-stage detector called 2EMC is carried out. The detector is proposed in [1]. The 2EMC is composed of energy detector as a primary stage and maximum-minimum eigenvalue detector as a secondary stage. The 2EMC outperforms the two individual detectors in terms of the probability of detection for the same probability of false alarm. Regarding the complexity measured in the sensing time, the 2EMC sensing time is bounded by the sensing times of the two individual detectors. 2EMC incorporates noise estimation that is used by the energy detector, which makes it fully-blind and self-adapted detector. The noise estimator performance is express…

Optical Frequency Combs Generated in Silica Microspheres in the Telecommunication C-, U-, and E-Bands

2021

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are demanded for different applications including telecommunications. Extending operating spectral ranges is an important problem for wavelength-division multiplexing systems based on microresonators. We demonstrate experimentally three spectrally separated OFCs in the C-, U-, and E-bands in silica microspheres which, in principle, can be used for telecommunication applications. For qualitative explanation of the OFC generation in the sidebands, we calculated gain coefficients and gain bandwidths for degenerate four-wave mixing (FWM) processes. We also attained a regime when the pump frequency was in t…

MICROWAVE EFFECTS ON ACETYLCHOLINE-INDUCED CHANNELS IN CULTURED CHICK MYOTUBES

1988

The behavior of cultured myotubes from chick embryos exposed to microwaves has been experimentally analyzed. Recordings of acetylcholine-induced currents have been obtained via patch-clamp techniques using both cell-attached (single-channel current recording) and whole-cell (total current recording) configurations. During the exposure to low-power microwaves the frequency of the ACh-activated single channel openings decreased, while the ACh-induced total current showed a faster falling phase. Channel open time and conductance were not affected by microwave irradiation. It is concluded that the exposure to microwaves increases the rate of desensitization and decreases the channel opening pro…

Are better young readers more likely to confuse their mother with their mohter?

2021

One of the most replicated effects in the contemporary word recognition literature is the transposed-letter effect (TL effect): pseudowords created by the transposition of two letters (e.g., MOHTER) are often misread as the real word. This effect ruled out those accounts that assume that letter position is encoded accurately and led to more flexible coding schemes. Here, we examined whether reading skill modulates this effect. The relationship between reading skill and the TL effect magnitude is a contentious issue both empirically and theoretically. The present lexical decision experiment was designed to shed some light on the relationship between reading skill and the TL effect magnitude…

Developing MLS Location-Based Service Pilot System

2002

Development of mobile networks and terminals provides basis for advanced mobile services and applications. One of the new features is support for locating the mobile user by her/his terminal. The Location-Based Services (LBS), utilising this feature, are expected to form an important class of the new services. At the Information Technology Research Institute, University of Jyvaskyla, LBSs have been studied in MultiMeetMobile research project. The project developed an LBS pilot system, called MLS. This paper presents the experiences collected during the development of the LBS pilot and describes the MLS system.

Nordic stock market integration

2001

Exploring Training Options for RF Sensing Using CSI

2018

This work analyzes human behavior recognition approaches using WiFi channel state information from the perhaps less usual point of view of training and calibration needs. With the help of selected literature examples, as well as with more detailed experimental insights on our own Doppler spectrum-based approach for physical motion/presence/cardinality detection, we first classify the diverse forms of training so far employed into three main categories (trained, trained-once, and training-free). We further discuss under which conditions it is possible to move toward lighter forms of calibration or even succeed in devising fully untrained model-based solutions. Our take home messages are main…

Left-handed metamaterial coatings for subwavelength-resolution imaging

2012

We report on a procedure to improve the resolution of far-field imaging by using a neighboring high-index medium that is coated with a left-handed metamaterial. The resulting plot can also exhibit an enhanced transmission by considering proper conditions to retract backscattering. Based on negative refraction, geometrical aberrations are considered in detail since they may cause a great impact in this sort of diffraction-unlimited imaging by reducing its resolution power. We employ a standard aberration analysis to refine the asymmetric configuration of metamaterial superlenses. We demonstrate that low-order centrosymmetric aberrations can be fully corrected for a given object plane. For su…

Variational multiframe restoration of images degraded by noisy (stochastic) blur kernels

2013

This article introduces and explores a class of degradation models in which an image is blurred by a noisy (stochastic) point spread function (PSF). The aim is to restore a sharper and cleaner image from the degraded one. Due to the highly ill-posed nature of the problem, we propose to recover the image given a sequence of several observed degraded images or multiframes. Thus we adopt the idea of the multiframe approach introduced for image super-resolution, which reduces distortions appearing in the degraded images. Moreover, we formulate variational minimization problems with the robust (local or nonlocal) L^1 edge-preserving regularizing energy functionals, unlike prior works dealing wit…