Search results for " Sensor"
showing 10 items of 1714 documents
Enhanced Reflectivity Change and Phase Shift of Polarized Light: Double Parameter Multilayer Sensor
2022
Herein, the concept of point of darkness based on polarized light phase difference and absorption of light is demonstrated by simulations using low refractive index and extinction coefficient semiconductor and dielectric, and high refractive index nonoxidizing metal multilayer thin film structures. Several multilayer sensor configurations show great sensitivity to thickness and refractive index variation of the detectable material by measuring the reflectivity ratio {\Psi} and phase shift {\Delta}. Focus is on such multilayers, which have sensitivity to both parameters ({\Psi}, {\Delta}) in the visible spectral range, thus opening the possibility for further research on a new biomedical sen…
Automatic tunable and reconfigurable fiberoptic microwave filters based on a broadband optical source sliced by uniform fiber Bragg gratings.
2002
We demonstrate an automatic tunable transversal notch filter based on uniform fiber Bragg gratings and a broadband optical source. High tunability can be performed by stretching the fiber with the gratings written in series. Also, high sidelobe supression can be achieved by introducing tunable attenuators in a parallel configuration of the gratings.
Quantum coherence and entanglement with ultracold atoms in optical lattices
2008
At nanokelvin temperatures, ultracold quantum gases can be stored in optical lattices, which are arrays of microscopic trapping potentials formed by laser light. Such large arrays of atoms provide opportunities for investigating quantum coherence and generating large-scale entanglement, ultimately leading to quantum information processing in these artificial crystal structures. These arrays can also function as versatile model systems for the study of strongly interacting many-body systems on a lattice.
COMPLEXITY, NOISE AND QUANTUM INFORMATION ON ATOM CHIPS
2008
The realization of quantum logic gates with neutral atoms on atom chips is investigated, including realistic features, such as noise and actual experimental setups.
Thermal sensor based on a polymer nanofilm
2016
In this work, we have developed a thermal sensor based on poly(3,4 ethylenedioxythiophene) (PEDOT) nanofilms as thermoelectric material. The PEDOT nanofilms have been synthesized by the electrochemical polymerization method. The thicknesses of the films were around 120 nm. The doping level of PEDOT was controlled by chemical reduction using hydrazine. The achieved Seebeck coeficient is 40 uV/K. A PEDOT nanofilm was integrated into an electronic circuit that amplifies the voltage originated from the Seebeck effect. The temperature increment produced by a fingerprint touching the film is enough to switch on a light emitting diode. Peer Reviewed
Tuning Of Organic Heterojunction Conductivity By The Substituents' Electronic Effects In Phthalocyanines For Ambipolar Gas Sensors
2021
Abstract Exploiting organic heterojunction effects in electrical devices are an important strategy to improve the electrical conductivity, which can be utilized into improving the conductometric gas sensors performances. In this endeavor, the present article reports fabrication of organic heterostructures in a bilayer device configuration incorporating octa-substituted nickel phthalocyanines (NiPc) and radical lutetium bis-phthalocyanine (LuPc2) and investigates their sensing properties towards NH3 vapor. NiPc having hexyl sulfanyl, hexyl sulfonyl and p-carboxyphenoxy moieties are synthesized, which electronic effects are electron donating, accepting and moderate accepting, respectively, al…
Auto calibration of a cone-beam-CT
2012
Purpose: This paper introduces a novel autocalibration method for cone-beam-CTs (CBCT) or flat-panel CTs, assuming a perfect rotation. The method is based on ellipse-fitting. Autocalibration refers to accurate recovery of the geometric alignment of a CBCT device from projection images alone, without any manual measurements. Methods: The authors use test objects containing small arbitrarily positioned radio-opaque markers. No information regarding the relative positions of the markers is used. In practice, the authors use three to eight metal ball bearings (diameter of 1 mm), e.g., positioned roughly in a vertical line such that their projection image curves on the detector preferably form l…
Optimization of flat area coverage under connectivity constraint in wireless sensor networks
2022
A wireless sensor network consists of a set of small autonomous units that interact via a network built by their communication modules. They observe their environment, capture information, then manage this information according to their computing and/or storage capacity. To effectively accomplish their task(s), they need to cover as much of the area of interest as possible. It is therefore essential to quantify the quality of their coverage. In this thesis, we therefore seek to best cover an area of interest, with a precise number of sensors. While taking into account the possible overlaps between sensors, we first deploy in a zone of regular dimensions and evaluate the exact coverage using…
A greedy perturbation approach to accelerating consensus algorithms and reducing its power consumption
2011
The average consensus is part of a family of algorithms that are able to compute global statistics by only using local data. This capability makes these algorithms interesting for applications in which these distributed philosophy is necessary. However, its iterative nature usually leads to a large power consumption due to the repetitive communications among the iterations. This drawback highlights the necessity of minimizing the power consumption until consensus is reached. In this work, we propose a greedy approach to perturbing the connectivity graph, in order to improve the convergence time of the consensus algorithm while keeping bounded the power consumption per iteration step. These …
Spike train statistics for consonant and dissonant musical accords in a simple auditory sensory model
2010
The phenomena of dissonance and consonance in a simple auditory sensory model composed of three neurons are considered. Two of them, here so-called sensory neurons, are driven by noise and subthreshold periodic signals with different ratio of frequencies, and its outputs plus noise are applied synaptically to a third neuron, so-called interneuron. We present a theoretical analysis with a probabilistic approach to investigate the interspike intervals statistics of the spike train generated by the interneuron. We find that tones with frequency ratios that are considered consonant by musicians produce at the third neuron inter-firing intervals statistics densities that are very distinctive fro…