Theoretical investigation of active listening behavior based on the echolocation of CF-FM bats

Bats perceive the three-dimensional (3D) environment by emitting ultrasound pulses from their nose or mouth and receiving echoes through both ears. To detect the position of a target object, it is necessary to know the distance and direction of the target. Certain bat species synchronize the movement of their pinnae with pulse emission, and it is this behavior that enables 3D direction detection. However, the significance of bats’ ear motions remains unclear. In this study, we construct a model of an active listening system including the motion of the ears, and conduct mathematical investigations to clarify the importance of ear motion in 3D direction detection. The theory suggests that only certain ear motions, namely three-axis rotation, accomplish accurate and robust 3D direction detection. Our theoretical analysis also strongly supports the behavior whereby bats move their pinnae in the antiphase mode. In addition, we provide the conditions for ear motions to ensure accurate and robust direction detection, suggesting that simple shaped hearing directionality and well-selected uncomplicated ear motions are sufficient to achieve precise and robust 3D direction detection. Our findings and mathematical approach have the potential to be used in the design of active sensing systems in various engineering fields.

Compact 3 × 1 Matrix Converter Module Based on the SiC Devices with Easy Expandability

This paper discusses a new approach for building a compact all-in-one matrix converter module based on SiC semiconductors arranged in a common source connection. The used transistors are in the D2PAK package. The design of the module is divided into two parts, namely a power module designed at one-layer aluminum substrate printed circuit board (PCB) to ensure good thermal performance and voltage isolation between the module and heatsink. The second board is responsible for the SiC driving and is mounted at the top of the power PCB and consists of metal-oxide semiconductor field effect transistor (MOSFET) drivers, isolated power supplies, a current direction detection circuit, and current value sensors. In the paper, the proper function of the SiC MOSFET drivers, current direction detection, and current measurement sensors were evaluated. Finally, 3D design together with the final prototype is presented. The modules contain three bidirectional cells for interconnection three input voltage sources and one output phase. The uniqueness and novelty of the presented module are the compactness and easy expandability of the module to achieve higher power outputs and multiphase applications such as five phase machines.

Sound arrival direction and acoustic scene analysis for the monitoring of airport noise

The authors have developed a sound direction detection method based on the cross-correlation method and applied it to automatic monitoring of aircraft noise and identification of sound sources. As aircraft performance improves, noise decreases, and people are interested in and dissatisfied with low-level noise aircraft, especially in urban areas where environmental noise and aircraft noise combine to complicate the acoustic environment. Therefore, it is necessary to monitor and to measure not only aircraft noise but also environmental noise. Since our surveillance is aircraft noise, it is important to analyze noise exposure from acoustic information rather than trucks or images. In this report, we will look back on the development process of this sound direction detection technology, show examples of helicopters and application examples of acoustic scene analysis to high-altitude aircraft, and consider the latest situation realized as acoustic environment monitoring. We believe that this analysis will make it easier to understand the noise exposure situation at the noise monitoring station. It also describes the future outlook for this method.

Mechanism of Motion Direction Detection Based on Barlow’s Retina Inhibitory Scheme in Direction-Selective Ganglion Cells

Previous studies have reported that directionally selective ganglion cells respond strongly in their preferred direction, but are only weakly excited by stimuli moving in the opposite null direction. Various studies have attempted to elucidate the mechanisms underlying direction selectivity with cellular basis. However, these studies have not elucidated the mechanism underlying motion direction detection. In this study, we propose the mechanism based on Barlow’s inhibitory scheme for motion direction detection. We described the local motion-sensing direction-selective neurons. Next, this model was used to construct the two-dimensional multi-directional detection neurons which detect the local motion directions. The information of local motion directions was finally used to infer the global motion direction. To verify the validity of the proposed mechanism, we conducted a series of experiments involving a dataset with a number of images. The proposed mechanism exhibited good performance in all experiments with high detection accuracy. Furthermore, we compare the performance of our proposed system and traditional Convolution Neural Network (CNN) on motion direction prediction. It is found that the performance of our system is much better than that of CNN in terms of accuracy, calculation speed and cost.