The use of arrays of microphones having a large number of elements (hundreds) is now in place in research laboratories, and will soon be practical for real applications. In rooms of auditorium or conference size, a large number of microphones will virtually always imply that the aperture will be large compared to the focal distance. This requires understanding the volume selectivity of irregula...

The focal point of a high-numerical-aperture (NA) ultrasonic transducer can be used as a virtual point detector. This virtual point detector detects omnidirectionally over a wide acceptance angle. It also combines a large active transducer surface and a small effective virtual detector size. Thus the sensitivity is high compared with that of a real point detector, and the aperture effect is sma...

This paper studies the effects of temperature and aperture size on the nanojet ejection process by means of molecular dynamics simulation using the Lennard-Jones potential. According to the analysis, it can be seen that the spurting atoms from the nanojet aperture are more evenly distributed as the temperature is increased. However, as the temperature lowers, the atoms easily concentrate on the...

− The calibration of radiation thermometers requires knowledge of the target size effect on the thermometer output, namely the size of source effect (SSE). The measurement of an instrument SSE allows to calculate a correction, or an estimation for this source of uncertainty. For a correct determination of SSE it is necessary to use large aperture radiation sources of uniform spectral radiance. ...

As opposed to visual imaging, biosonar imaging of spatial object properties represents a challenge for the auditory system because its sensory epithelium is not arranged along space axes. For echolocating bats, object width is encoded by the amplitude of its echo (echo intensity) but also by the naturally covarying spread of angles of incidence from which the echoes impinge on the bat's ears (s...

In this paper, we present a novel signal processing method for video synthetic aperture radar (ViSAR) systems, which are suitable for operation in unmanned aerial vehicle (UAV) environments. The technique improves aspects of the system’s performance, such as the frame rate and image size of the synthetic aperture radar (SAR) video. The new ViSAR system is based on a frequency-modulated continuo...

The 'just noticeable difference' (JND) represents the minimum amount by which a stimulus must change to produce a noticeable variation in one's perceptual experience and is related to initial stimulus magnitude (i.e., Weber's law). The goal of the present study was to determine whether aperture shaping for visually derived and memory-guided grasping elicit a temporally dependent or temporally i...