Search results for "FREQUENCY"
showing 10 items of 2158 documents
Acoustic methods for measuring the porosities of porous materials incorporating dead-end pores
2013
International audience; The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont et al. [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high …
400– to 1000–nm imaging spectrometer based on acousto-optic tunable filters
2004
An imaging spectrometer covering the 400-1000 nm band has been conceived and developed. The system is based on an Acousto-Optic Tunable Filter (AOTF) attached to a high performance digital camera. The AOTF permits the selection of spectral bands with an RF signal in the range of 70-210 MHz. The range is covered using two transducers attached to a single crystal. Although the idea is not new it covers a broader spectrum than previous systems. It includes a telecentric optical system that enhances system efficiency, by ensuring that the chief ray of each light cone emerges out of this doublet parallel to the optical axes. Additionally, an smart choice of integration time reduces the dependenc…
Boundedness and compactness of operators related to time-frequency analysis
2018
En esta tesis, estudiamos diferentes aspectos de los operadores relacionados con el análisis tiempo-frecuencia. Cada operador lineal y continuo de la clase de Schwartz en su dual, el espacio de distribuciones temperadas, se puede escribir como un operador integral con núcleo K, o también como un operador integral de Fourier (de hecho, pseudodiferencial). Las diferentes condiciones en el núcleo o el símbolo y la fase (en el caso de los operadores integrales de Fourier) permiten extender el operador a varios espacios de funciones y distribuciones. A continuación detallamos los contenidos de la memoria. En el primer capítulo presentamos la notación, las definiciones de algunos espacios, de suc…
A one-dimensional model for dynamic analysis of generally layered magneto-electro-elastic beams
2013
Abstract A new one-dimensional model for the dynamic problem of magneto-electro-elastic generally laminated beams is presented. The electric and magnetic fields are assumed to be quasi-static and a first-order shear beam theory is used. The electro-magnetic problem is first solved in terms of the mechanical variables, then the equations of motion are written leading to the problem governing equations. They involve the same terms of the elastic dynamic problem weighted by effective stiffness coefficients, which take the magneto-electro-mechanical couplings into account. Additional terms, which involve the third spatial derivative of the transverse displacement, also occur as a result of the …
Audiologic profile of OSAS and simple snoring patients: the effect of chronic nocturnal intermittent hypoxia on auditory function
2016
The objective of this work was to study the effect of nocturnal intermittent hypoxia on auditory function of simple snoring patients and subjects affected by OSAS; we compared the audiologic profile with the severity of OSAS to detect early signs of cochlear damage. One hundred-sixty patients underwent overnight polysomnography, micro-otoscopy, multi-frequency audiometry, acufenometry, TEOAE recording and d-ROMs test. All subjects were divided in four groups, based on presence/absence of AHI (simple snoring without OSAS, mild OSAS, moderate OSAS, severe OSAS). Sixty (37.5 %) patients were not affected by OSAS, 58 (36.25 %) presented a mild OSAS, 18 (11.25 %) a moderate OSAS and 24 (15 %) a …
The development of “junk”. Irregularization strategies of have and say in the Germanic languages
2001
Although it is a wellknown fact that the most frequent verbs are the most irregular ones (if not suppletive), it is rarely asked how they became irregular. This article deals with the irregularization process of two originally regular (weak) verbs, HAVE and SAY in the Germanic languages, e.g. have, but has/’s and had/’d (instead of regular *haves/*haved) or say [sei], but says [sez] and said [sed] in English. Other verbs, such as DO, GO, STAND, BE, COME, and so on, also tend to irregularizations again and again without any apparent reason. In contrast to HAVE and SAY these verbs have always been rather irregular, at least dating from their first written records.
Whispering gallery mode resonator sensors referenced to saturated absorption lines in rubidium atoms and a fs frequency comb
2019
Optical Whispering Gallery Mode Resonators (WGMR) can be produced by many methods, for example, by flame melting of silica fibers [1], by polishing of crystals [2], by optical lithography, by solidifying transparent materials, or using commercially available microspheres. They confine light by the total internal reflection and do not need mirror coatings. A part of radiation is traveling outside the WGMR as an evanescent wave and it is used for sensing applications. WGMRs are becoming increasingly popular as biosensors [3] when their surface is covered with antibodies to provide selectivity. Advantage is that light circulates in the resonator and interacts many times with a few molecules at…
Placental alkaline phosphatase types in Germany
1974
The phenotypes of placental alkaline phosphatase were determined in a sample of 231 Germans and 109 non-Germans. The observed gene frequencies of the German sample were \({\text{Pl}}^{{\text{S}}_{\text{1}} } {\text{ = 0}}{\text{.654}}\), \({\text{Pl}}^{{\text{F}}_{\text{1}} } {\text{ = 0}}{\text{.247}}\), and \({\text{Pl}}^{{\text{I}}_{\text{1}} } {\text{ = 0}}{\text{.097}}\). No association could be found with placental weight. Lower birth weight was correlated with an increase of the \({\text{Pl}}^{{\text{I}}_{\text{1}} } \) gene frequency.
Fractional Modeling of the AC Large-Signal Frequency Response in Magnetoresistive Current Sensors
2013
Fractional calculus is considered when derivatives and integrals of non-integer order are applied over a specific function. In the electrical and electronic domain, the transfer function dependence of a fractional filter not only by the filter order n, but additionally, of the fractional order α is an example of a great number of systems where its input-output behavior could be more exactly modeled by a fractional behavior. Following this aim, the present work shows the experimental ac large-signal frequency response of a family of electrical current sensors based in different spintronic conduction mechanisms. Using an ac characterization set-up the sensor transimpedance function is obtain…
Performance evaluation of the MPE-iFEC Sliding RS Encoding for DVB-H streaming services
2008
This article studies the performance of the Sliding RS Encoding (SRSE) in the transmission of streaming services in DVB-H (Digital Video Broadcasting - Transmission System for Handheld Terminals) networks. The SRSE forms part of a set of specifications called MPE-iFEC which has been recently defined in the DVB-SH (Digital Video Broadcasting - Satellite Services to Handheld Devices) standard and is fully compatible with the link layer of DVB-H. MPE-iFEC is capable of encoding information related to different datagram bursts in a jointly manner in order to counteract the long signal blockages expected in satellite reception. This is what is usually referred to as Multi-Burst Encoding (MBE) an…