scholarly journals Phenomenon of a single cause of the cluster-dipole nature of the observability of the area of hydrophysical disturbances from a submarine moving object by a laser beam and radar signal

2019 ◽  
pp. 62-71
Author(s):  
Vladimir Ivanovich Polenin
Keyword(s):  
Liquid Crystals ◽  
Laser Beam ◽  
Electromagnetic Radiation ◽  
Water Surface ◽  
Moving Object ◽  
Sea Surface ◽  
Radar Signal ◽  
Similar Nature ◽  
Radar Station ◽  
Underwater Object

Relationships of cause and effect which are the cornerstone of the phenomenon of observability of area of hydrophysical indignations from an underwater moving object, including its exit to a sea surface when lighting the area in the thickness of water by a laser beam and radiation of the sea surface over an object with a radar station signal are described in the article. In the stationary marine environment the laser beam creates a backscattering signal of a fixed level. In the area of hydrodynamic indignations from an underwater moving object the signal of a backscattering of variable brightness to the relevant structure and level of indignations is seen. The similar phenomenon of a backscattering of the electromagnetic radiation of radar station that creates glare effects on the screen of radar station in a zone of an exit of hydrodynamic indignations is observed on a water surface. It is shown that these phenomenons have similar nature caused by the change of dimensional orientation of dipoles of molecules and liquid crystals clusters of water in the field of the hydrodynamic indignations accompanying the moving of an underwater object. Establishing of this characteristic, in case of its confirmation by test data, meets the requirements of qualification of opening.

scholarly journals Effects of the Wavenumber Spectrum of a Sea Surface on Laser Beam Reflection

1979 ◽  
Vol 32 (5) ◽  
pp. 469 ◽  
Author(s):  
DM Phillips
Keyword(s):  
Laser Beam ◽  
Water Surface ◽  
Pulsed Laser ◽  
Sea Surface ◽  
Beam Diameter ◽  
The Mean ◽  
Wavenumber Spectrum ◽  
Beam Reflection ◽  
Depth Sounding ◽  
Pulsed Laser Beam

The angular and temporal distributions of energy in the reflection of a pulsed laser beam from a sea surface depend on the diameter of the beam and on the wavenumber spectrum of the water surface. Theoretical expressions are derived for the influence on the reflection of the mean height and slope of waves in the illuminated area as well as the variation of the height and slope within this area. The results are applied to airborne lasers for wave height profiling, altimetry and water depth sounding. The optimum beam diameter depends on both the application and the wavenumber pectrum of the water surface.

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

2014 ◽  
Vol 22 (1) ◽  
Author(s):  
T. Devi ◽  
B. Choudhury ◽  
A. Bhattacharjee ◽  
R. Dabrowski
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Laser Beam ◽  
Order Parameter ◽  
Refractive Indices ◽  
Optical Parameters ◽  
Optical Studies ◽  
High Birefringence ◽  
Two Samples ◽  
Direct Extrapolation

AbstractOptical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4′-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4′-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.

scholarly journals Result of modeling temperature anomalies on the water surface of the research basin of the institute of hydromechanics NAS of Ukraine

2018 ◽  
pp. 40-45
Author(s):  
Oleksandr Fedorovsky ◽  
Vitalii Filimonov ◽  
Iryna Piestova ◽  
Stanislav Dugin ◽  
Vladyslav Yakymchuk ◽  
...  
Keyword(s):  
Water Surface ◽  
Water Layer ◽  
Sea Surface ◽  
National Academy Of Sciences ◽  
Near Surface ◽  
Aerial Photos ◽  
Temperature Anomalies ◽  
Structural And Textural Parameters ◽  
The Difference ◽  
Hydrocarbon Deposits

The results of the research and physical modeling of temperature anomalies of natural or man-made origin on the water surface are presented.  The information for the research was obtained from the experimental basin of the Institute of Hydromechanics of the National Academy of Sciences of Ukraine from the self-propelled model as the generator of hydrodynamic processes. The information obtained after image processing allowed to significantly expand the existing ideas about the mechanism of formation of anomalies on the open surface with the hydrodynamic disturbances from hydrocarbon deposits and moving submerged object. The interaction of the emerging hydrodynamic disturbances with the near-surface water layer and the occurrence of unmasking temperature anomalies on the open sea surface have a lot in common between the hydrocarbon deposits and the moving submerged object. The application of the difference of the above structural and textural parameters by calculating the value of "entropy" has been proposed as the informative feature for decoding the images of the water surface with the presence of hydrocarbon deposits or moving immersed objects. The decoding of temperature anomalies consists of two stages: learning and proper decoding. The first stage is the supervised learning, during which the system is being researched using the existing set of images, in which only the background and no hydrocarbon deposits or moving submerged object. Training is carried out in order to determine the signs of belonging to the background or hydrocarbon deposits, moving submerged object. It was determined that the background has minimal entropy values, and with the appearance of an anomaly, the entropy grows to the maximum value, after which, as the temperature trace dissipates, it begins to fall to background values. This confirms the informativity of the entropy feature for decoding the optical anomalies of man-made and natural origin on the sea surface from aerial photos.

scholarly journals Vertical Motions Damping Model Test of a Lifeboat Lowered Onto a Flat Sea Surface

2018 ◽  
Vol 25 (s1) ◽  
pp. 51-55
Author(s):  
Aleksander Kniat ◽  
Paweł Dymarski
Keyword(s):  
Mathematical Model ◽  
Model Test ◽  
Water Surface ◽  
Vertical Motion ◽  
Sea Surface ◽  
Damping Factor ◽  
Initial Speed ◽  
The Mathematical Model ◽  
Damping Model

Abstract The article presents the experiment’s results of the lifeboat model lowered with an initial speed and then released to fall onto a flat water surface. The purpose of the research is to determine the trajectory of the vertical boat motion and describe it with a mathematical model. This is closely related to determining the damping factor since the vertical motion is damped and the lifeboat gets balanced and stops moving after some time. The procedure of selecting parameters in the mathematical model to adjust to the results of the experiment was described in details. The summary describes the imperfections of the presented damping model and their probable causes.

Sign in / Sign up

Export Citation Format

Share Document