1,720,959 research outputs found
Individual listening zone with frequency-dependent trim of measured impulse responses
No full textAcoustic Contrast Control (ACC) has been widely used to achieve individual audio delivery in shared environments. The effectiveness of this method is reduced when the control is performed in reverberant environments. Even if control filters are computed using measured transfer functions, the robustness of the system is affected by the presence of reverberation in the plant matrix. In this paper a new optimization method is presented to improve the ACC algorithm by applying a frequency-dependent windowing of the measured impulse response used for the filter computation, thus removing late reflections. The effects of this impulse response optimization are presented by means of sound zoning results obtained from experimental measurements performed in a car cabin
Optimisation of the target sound fields for the generation of independent listening zones in a reverberant environment
No full textThe Pressure Matching Method (PMM) has been widely used in individual listening zones (ILZ) systems to create multiple independent sound zones in the same environment. This method aims to reproduce a set of target acoustic fields in several control zones, using one or more loudspeaker arrays. These target fields are parameters of the ILZ algorithm that are defined at the design stage. In this work, we compare the effects of several target sound field alternatives on the sound field control system performance and robustness. The proposed target fields prevent the ILZ system from focusing its effort on unessential tasks such as the dereverberation of the acoustic environment. More specifically, we compare target acoustic fields of a single active loudspeaker, of several active and in-phase loudspeakers or of a set of loudspeakers acting as a beamformer steered towards one of the zones to be controlled. Results of simulations and experiments obtained with one compact loudspeaker array in the interior of a real car are presented as well as a study on the robustness to perturbations of the solutions obtained with the various choices of target acoustic fields
Impact of on-body IMU placement on inertial navigation
No full textEven though technology-aided personal navigation is an extensively studied research topic, approaches based on inertial sensors remain challenging. In this study, the authors present a comparison between different inertial systems, investigating the impacts of on-body placement of Inertial Measurement Units (IMUs) and, consequently, of different algorithms for the estimation of the travelled path on the navigation accuracy. In particular, the system performance is investigated considering two IMU placements: (i) on the feet and (ii) on the lower back. Sensor fusion is then considered in order to take advantage of the strengths of each placement. The results are validated through an extensive data collection in indoor and outdoor environments
A multifloor hybrid inertial/barometric navigation system
No full textThis paper describes the development of a multifloor hybrid inertial/barometric navigation system. The prototype integrates several Magnetic Angular Rate and Gyroscope (MARG) sensors and a barometer. The inertial (MARG) sub-system, by properly processing the signals collected by the MARG sensors placed on the test subject's feet, reconstructs the two-dimensional navigation pattern by applying a Zero velocity UPdaTe (ZUPT) technique. Three different sensors' configurations are investigated in order to find the best performing set-up. A simpler configuration with a single MARG sensor is also considered to derive a reference performance benchmark without multiple MARG sensor fusion. The barometer, connected via usb to a Freakduino board, is used to detect the floor change. The fusion of inertial and barometric signals allows to fully reconstruct the movement of a person in both indoor and outdoor environments. The main goal of the proposed system is to allow accurate personal navigation without any external reference (i.e., radio signals, satellite signals, etc.). Considering a closed path, the relative distance error between the starting point and the final estimated position is below 2.5% of the total traveled distance
On single sensor-based inertial navigation
No full textIn this paper, we compare two novel algorithms for pedestrian navigation based on signals collected by a single wearable Magnetic, Angular Rate, and Gravity (MARG) sensor. The two navigation algorithms, denoted as Enhanced Pedestrian Dead Reckoning (EPDR) and De-Drifted Propagation (DDP), require the placement of the MARG sensor on the foot or on the chest of the test subject, respectively. Different methods for gait characterization are compared, evaluating navigation dynamics by using data collected through an extensive experimental campaign. The main goal of this research is to investigate the peculiarities of different inertial navigation algorithms, in order to highlight the impact of the sensor's placement, together with inertial sensor issues. Considering a closed path (i.e., ending at the starting point), the relative distance error between the starting point and the final estimated position is about 2% of the total travelled distance for both DDP and EPDR navigation algorithms. On the other hand, the error between the initial heading angle and the final estimated one is approximately 10° for EPDR and 7° for DDP, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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