An Inverse Microphone Array Method for the Estimation of a Rotating Source Directivity

Microphone arrays methods are useful for determining the location and magnitude of rotating acoustic sources. This work presents an approach to calculating a discrete directivity pattern of a rotating sound source using inverse microphone array methods. The proposed method is divided into three consecutive steps. Firstly, a virtual rotating array method that compensates for motion of the source is employed in order to calculate the cross-spectral matrix. Secondly, the source locations are determined by a covariance matrix fitting approach. Finally, the sound source directivity is calculated using the inverse method SODIX on a reduced focus grid. Experimental validation and synthetic data from a simulation are used for the verification of the method. For this purpose, a rotating parametric loudspeaker array with a controllable steering pattern is designed. Five different directivity patterns of the rotating source are compared. The proposed method compensates for source motion and is able to reconstruct the location as well the directivity pattern of the rotating beam source.

Locative Ps as general relators

Based mostly on the Romance languages, we provide evidence for the conclusion that oblique adpositions involved in the encoding of location and direction do not contribute a specific, fixed spatial meaning. On the contrary, they are general relators, relating a complement to an event by establishing an inclusion relation between them. Locatives are specializations of the basic relational inclusion content. State-in, motion-to and motion-from interpretations depend on the interaction of these simple relators with the structure of the event. Specifically, the relator may attach at the level of the Result phrase (goal, motion-to) or at the level of the Cause layer (source, motion-from). Furthermore, the Romance languages provide evidence for differential encoding of non-animate vs. animate location, which we refer to as locative DOM, presenting and discussing various instances of it.

Interferometric imaging with LOFAR remote baselines of the fine structures of a solar type-IIIb radio burst

Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A sub-category of solar radio bursts with short time duration may be used as a proxy to understand wave generation and propagation within the corona. Aims. Complete case studies of the source size, position, and kinematics of short term bursts are very rare due to instrumental limitations. A comprehensive multi-frequency spectroscopic and imaging study was carried out of a clear example of a solar type IIIb-III pair. Methods. In this work, the source of the radio burst was imaged with the interferometric mode, using the remote baselines of the LOw Frequency ARray (LOFAR). A detailed analysis of the fine structures in the spectrum and of the radio source motion with imaging was conducted. Results. The study shows how the fundamental and harmonic components have a significantly different source motion. The apparent source of the fundamental emission at 26.56 MHz displaces away from the solar disk center at about four times the speed of light, while the apparent source of the harmonic emission at the same frequency shows a speed of < 0.02 c. The source size of the harmonic emission observed in this case is smaller than that in previous studies, indicating the importance of the use of remote baselines.

Source size and Position of a Type IIIb-III Pair with LOFAR

&lt;p&gt;Solar radio bursts originate mainly from high energy electrons accelerated by solar eruptions like solar flares, jets, and coronal mass ejections (CMEs). &amp;#160;A sub-category of solar radio bursts with a short time duration may be used as a proxy to understand the wave generation and propagation within the corona. &amp;#160;Complete case studies of the source size, position, and kinematics of short-term bursts are very limited due to instrumental limitations.&lt;br&gt;LOw-Frequency-ARray (LOFAR) is an advanced radio antenna array. It is capable of a variety of processing operations including correlation for standard interferometric imaging, the tied-array beam-forming, and the real-time triggering on incoming station data-streams. With recently upgraded LOFAR, we can achieve high spatial and temporal imaging for solar radio bursts.&lt;br&gt;Here we present a detailed analysis of the fine structures in the spectrum and of the radio source motion with imaging, the radio source of a type IIIb-III pair was imaged with the interferometric mode using the remote baselines of the (LOFAR). This study shows how the fundamental and harmonic components have a significant different source motion. &amp;#160;The apparent source of the fundamental emission at 26 MHz is about 4 times the speed of light, while the apparent source of the harmonic emission shows a speed of &lt; 0.02 c. &amp;#160;We show that the apparent speed of the fundamental source is more affected by the scattering and refraction of the coronal medium.&lt;/p&gt;