1,721,009 research outputs found
MULTISQUEEZING OF MECHANICAL STATES AND BACK-ACTION EVASION MEASUREMENTS
No full textA technique is proposed to improve the squeezing of the mechanical noise in a back-action evasion measurement. The scheme is based on the use of a parametric multipump system and, in the limit of many pump components, approaches a stroboscopic measurement. A simple model of the back-action evasion effect for this scheme is developed. Experimental evidence of a significant increase in the squeezing with respect to the two-pump scheme and in accordance with the model is reported
GENERALIZED BACK-ACTION EVASION SCHEMES FOR THE DETECTION OF WEAK CLASSICAL FORCES
No full textAfter a general review of the analysis already available for back-action evasion schemes a perturbative approach is introduced and applied to a simple case. As a generalization of the back-action evasion schemes the concept of optimal pumping spectrum is introduced: it works for a unified treatment of stroboscopic and continuous quantum nondemolition strategies. Generalized back-action evasion strategies are introduced and studied in simple applications: they open the possibility for developing high-sensitivity schemes for the measurements of small forces. In particular, estimates of the noise figure for generalized back-action evasion transducers are discussed in detail
MODEL ORDER SELECTION OF INTERFEROMETRIC SAR SIGNALS CORRUPTED BY MULTIPLICATIVE AND ADDITIVE NOISE
No full textX-band Sea Clutter Non-Stationarity: The Influence of Long Waves
No full textIn this paper, we deal with the problem of modeling the backscattering from sea surface for low-grazing-angle and high-resolution radar systems. Based on the electromagnetic two-scale model, we analyzed both the amplitude and frequency modulations induced on the small-scale Bragg resonant waves by the large-scale surface tilt and advection due to the swell presence. Evidence of sea-clutter nonstationarity has been verified and the relationship between the variations of clutter spectral features, such as texture, Doppler centroid, and bandwidth, have been studied by processing real sea-clutter data recorded by the IPIX radar of McMaster University, Hamilton, ON, Canada. An autoregressive nonstationary process is proposed and validated to model the physical phenomenon
1/f noise of STM tunnel probe as a function of temperature
No full textThe tunneling probe used in Scanning Tunneling Microscopy (STM) has been recently proposed as displacement sensor for resonant gravitational‐wave antennas[1]. At present the performance of the tunnel probe as displacement sensor are limited by the 1/f noise in the tunnel current which, at room temperature, lowers of three orders of magnitude the expected sensitivity in the KHz range: preliminary results indicate that at liquid helium temperature the tunnel probe is a shot noise limited device. To understand the origin of the 1/f noise we are carrying on systematic measurements of the tunnel current noise as a function of the temperature and for different materials; the experimental results will be presented during the conference. Due to the quantum mechanical nature of the tunnel probe we believe that noise measurements as a function of the temperature can give also some useful information on the fundamental origin of the 1/f noise
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Multiple Target Detection and Estimation by Exploiting the Amplitude Modulation Induced by Antenna Scanning. Part II: Detection
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