Development of an Instantaneous Velocity-Vector-Profile Method Using Conventional Ultrasonic Transducers

The velocity vector profile technique based on an ultrasound pulsed Doppler method can enrich the information of a flow field, however, it has shown a low availability because a new design of special transducers is required for each measurement case. This study proposes a new method of profiling the velocity vectors using conventional ultrasound transducers that are widely supplied to UVP (Ultrasound velocity profile) users. We constructed a configuration of the transducers to minimize the uncertainty of the detection points at the receivers, and a measurable distance was theoretically determined by the configuration. Two feasibility tests were carried out. One was a test for the assessment of the measurable distance, which agreed well with the theoretical distance. The other was the evaluation of the measurement of two-dimensional velocity vectors by the new method and it was performed in a towing tank facility without the velocity fluctuation. From the evaluation, it was confirmed that the measured vectors showed good agreement to the reference values, and their accuracy and precision were competitive compared to previous studies. The developed method was applied to two unsteady flows for demonstrations. The results clarified that the proposed method guarantees high availability and accuracy for the velocity vector profiles.

Distance measurement using the spherical wave fact of astronomical objects

Distance measurement is very important for astrophysics, and it is also an arduous task. Here we propose an independent method to measure the distances directly. Considering that electromagnetic waves are actually spherical waves from the source, people can get the distance of the source by accurately measuring the curvature of the spherical surface. The farthest measurable distance is roughly b2/b, where d is the separation of telescopes, and b is the position accuracy of the telescopes.

Design of Mechaless LiDAR Optical System With Large FOV Using Liquid Lens and Fisheye Lens

Mechaless LiDAR technology, which does not have a mechanical drive part, has been actively studied in order to increase the reliability of the LiDAR device at low cost and drive environment in order to more actively apply LiDAR technology to autonomous driving. Mechaless LiDAR technology, which has been mainly studied recently, includes 3D Flash LiDAR technology, MEMS mirror utilization method, and OPA (Optical Phased Array). However, these methods have not been developed rapidly as a key technology for achieving autonomous driving due to low stability of driving environment or remarkably low measurable distance and FOV (field of view) compared with mechanical LiDAR. In this study, we investigated the improvement of FOV by using a flux-deflecting liquid lens and a fisheye lens that can achieve fine spatial resolution through continuous voltage regulation. Based on the initial design results, it was examined that the FOV can be secured to 80 ° or more by utilizing a relatively simple fisheye lens composed of only spherical lenses.

Free Space Ranging Utilizing Chaotic Light

We report our recent works on free space ranging with chaotic light. Using a laser diode with optical feedback as chaotic source, a prototype of chaotic lidar has been developed and it can achieve a range-independent resolution of 18 cm and measurable distance of 130 m at least. And its antijamming performance is presented experimentally and numerically. Finally, we, respectively, employ the wavelet denoising method and the correlation average discrete-component elimination algorithm to detect the chaotic signal in noisy environment and suppress the side-lobe noise of the correlation trace.

Runoff and windblown vehicle spray from road surfaces, risks and measures for soil and water

Soil and surface water along roads are exposed to pollution from motorways. The main pollutants are polycyclic aromatic hydrocarbons (PAH), mineral oil, heavy metals and salt. These pollutants originate from vehicles (fuel, wires, leakage), wear and degradation of road surfaces and road furniture (i.e. crash barriers) and the application of de-icing salts. Runoff, vehicle spray and dry deposition disperse these contaminants into the soft shoulder (verges) of the roads and surface water to a measurable distance of about 50 up to more then 150 m from the road. Despite many monitoring programs, little is known about the risks of this diffuse pollution for soil and water quality and the geochemical and physical factors which determine these risks. Also little is known about the effects of possible measures. Therefore, extensive research has been carried out at two local motorways. Specific measurements on runoff, vehicle spray and effects of measures have been carried out for one year (13 months). This resulted in several new insights. The pollutants appear to adsorb effectively to natural soils. In vulnerable areas groundwater can be protected by adjusting the policy to removing the contaminated upper topsoil of the verges. Discharges of runoff into local surface water are not recommended.

MICROSCOPIC BLACK HOLE DETECTION IN UHECR: THE DOUBLE BANG SIGNATURE

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature.

Depth Illusion by Delayed 3-D Perception (‘Delayed Stereopsis Illusion’): A Novel Way to Determine Computation Times in Human Vision by Depth Reversal in Partially Occluded Moving Objects

Viewed through depth-reversing spectacles, nontransparent objects appear to cut ‘gaps’ into a patterned background. In moving objects this gap is seen to extend beyond the occluded area (‘delayed stereopsis illusion’, DSI): Its trailing border appears to lag behind by a precisely measurable distance, indicating a processing time of approximately 0.13 s to accomplish stereopsis [cf Morgan and Castet, 1995 Nature (London)378 380 – 383]. Other than in thigmaesthesia, there is no correction by antedating. Why is this delay not perceived in normal stereopsis? If an object is moving before some background, the background usually maintains its position; it may be occluded, or not. Depth information thus might be extrapolated to the continuously uncovered regions of the patterned background. Depth reversal demands that the occluded region of the background must jump behind the moving, occluding object. As this object is perceived to retain its distance, the background, as it is getting uncovered, must jump back into the foreground, where it can be perceived only after renewed calculation of binocular depth. The dependence of DSI on eye movements, disparity, velocity, motion direction, surface texture, illuminance, spatial frequency, and fractal dimension of the objects involved is currently being investigated in model systems which allow us to determine processing times of human stereopsis under well-defined conditions.