Underwater Orientation Research Articles

A bionic point-source polarisation sensor applied to underwater orientation

AbstractWith the characteristics of full autonomy and no accumulated errors, polarisation navigation shows tremendous prospects in underwater scenarios. In this paper, inspired by the polarisation vision of aquatic organisms, a novel point-source polarisation sensor with high spectral adaptability (400 nm–760 nm) is designed for underwater orientation. To enhance the environmental applicability of the underwater polarisation sensor, a novel sensor model based on the underwater light intensity attenuation coefficient and optical coupling coefficient is established. In addition, concerned with the influence of light intensity uncertainty on sensor performance underwater, an antagonistic polarisation algorithm is adopted for the first time, to improve the accuracy of angle of polarisation and degree of polarisation in the low signal-to-noise ratio environment underwater. Finally, indoor and outdoor experiments are carried out to evaluate the performance of the designed polarisation sensor. The results show that the designed point-source polarisation sensor can acquire polarised light and be used for heading determination underwater.

Research on Underwater Directional Swimming Skills of Divers

Abstract The article presents the results of research on the application of a physical exercise programme to improve the underwater orientation of military divers. The research was carried out on a group of 120 soldiers, some of whom (the study group) underwent additional training for 3 months. During the underwater straight-line swimming test in poor visibility conditions, the test group achieved statistically significantly better results than the control group. The test consisted in measuring the angle of deviation of the diver’s route from the given straight line.

Research on Underwater Directional Swimming Skills of Divers

Abstract The article presents the results of research on the application of a physical exercise programme to improve the underwater orientation of military divers. The research was carried out on a group of 120 soldiers, some of whom (the study group) underwent additional training for 3 months. During the underwater straight-line swimming test in poor visibility conditions, the test group achieved statistically significantly better results than the control group. The test consisted in measuring the angle of deviation of the diver’s route from the given straight line.

Underwater Pure Orientation Target Tracking Based on Adaptive Box Length KLD PF Algorithm

Aiming at the characteristics of underwater pure orientation target tracking, an adaptive box length Kullback-Leibler Distance (KLD) Particle Filter (PF) algorithm is proposed based on traditional adaptive KLD PF algorithm. When performing underwater pure orientation target tracking, the traditional adaptive KLD sampling may have a problem that the filtering accuracy is reduced or even invalid due to the fixed length of the KLD box. In the algorithm proposed in this paper, the length of the KLD box can be automatically adjusted according to the current particle distribution range, which can well solve the problem of precision degradation caused by the fixed KLD box length of the traditional adaptive KLD algorithm. The effectiveness of the adaptive box length KLD PF algorithm is verified by comparison with the traditional KLD PF algorithm in simulation. In this simulation, the adaptive box length KLD PF algorithm can effectively adapt to the changing environment of underwater tracking and has good tracking performance.

Ultrastructural, Sensory and Functional Anatomy of the Northern Elephant Seal (Mirounga angustirostris) Facial Vibrissae.

Vibrissae (whiskers) play a key role in underwater orientation in foraging phocids through vibrotactile sensation processing. Our aim was to evaluate the structure of northern elephant seal (NES) vibrissae by means of light (LM) and transmission electron microscopy (TEM), in order to elucidate their function. Vibrissal follicles were processed using standardized laboratory methods and LM/TEM techniques. Individual follicular axonal numbers were counted and axonal diameter measured and averaged. NES have mystacial, rhinal, supraorbital and labial vibrissae. The vibrissal follicles are histologically subdivided into a ring, upper and lower cavernous sinuses (LCS). Each vibrissa is innervated by the deep vibrissal nerve. The average number of axons per large mystacial vibrissa is 1804 (±123), rhinal 985 (±241), supraorbital 1,064 (±204) and 374 (±65) in labial vibrissa. The entire vibrissal system carries an estimated 148573 axons, and mystacial vibrissae alone have 125323 axons. Axonal conduction velocity for each vibrissal type is 55.26m/s for labial, 56.58m/s for rhinal and 35.88m/s for mystacial vibrissae. TEM and LM revealed a plethora of mechanoreceptors within the vibrissal follicles: Merkel cell-neurite complexes, lanceolate and pilo-Ruffini end organs. A vast number of sensory axons projecting from the entire vibrissal system indicate that the vibrissal sensory area takes up a large proportion of phocids' somatosensory cortex. In conclusion, NES has highly sensitive and finely tuned vibrotactile vibrissal sense organs.

In-situ Corrosion Measurements of WWII Shipwrecks in Chuuk Lagoon, Quantification of Decay Mechanisms and Rates of Deterioration

This paper is based on a series of measurements taken on WWII historic shipwrecks that resulted from the effects of Operation Hailstone in February 1944 on the Japanese merchant fleet which was assembled in Chuuk lagoon, Federated States of Micronesia. More than 65 shipwrecks and 250 aircraft were sunk during two main bombing raids. The vessels lost covered a wide range of underwater orientation and water depths and so provided a perfect suite of corrosion experiments. Since the fuel on board the aircraft was either readily burnt at the time or was lost through volatilisation, the wrecked planes present no pollution problems today. However the bunker fuel kept inside on-board storage tanks does present a real conservation management crisis. In-situ measurements on many vessels have determined how water depth, the localised wreck topography, dissolved oxygen levels, temperature and salinity affects the corrosion rate of cast iron and mild steel. Thus corrosion rates can be calculated with confidence.

Underwater and surface behavior of homing juvenile northern elephant seals

Northern elephant seals, Mirounga angustirostris, travel between colonies along the west coast of North America and foraging areas in the North Pacific. They also have the ability to return to their home colony after being experimentally translocated. However, the mechanisms of this navigation are not known. Visual information could serve an important role in navigation, either primary or supplementary. We examined the role of visual cues in elephant seal navigation by translocating three seals and recording their heading direction continuously using GPS, and acceleration and geomagnetic data loggers while they returned to the colony. The seals first reached the coast and then proceeded to the colony by swimming along the coast. While underwater the animals exhibited a horizontally straight course (mean net-to-gross displacement ratio=0.94±0.02). In contrast, while at the surface they changed their headings up to 360 deg. These results are consistent with the use of visual cues for navigation to the colony. The seals may visually orient by using landmarks as they swim along the coast. We further assessed whether the seals could maintain a consistent heading while underwater during drift dives where one might expect that passive spiraling during drift dives could cause disorientation. However, seals were able to maintain the initial course heading even while underwater during drift dives where there was spiral motion (to within 20 deg). This behavior may imply the use of non-visual cues such as acoustic signals or magnetic fields for underwater orientation.

Performance on the Portable Rod and Frame Test Predicts Variation in Learning the Kayak Roll

Expert performers in sports that include a high proportion of closed skills have often been found to score relatively high in field independence tests; a field-independent cognitive style may be advantageous for learning and performance of closed skills. The relationship between field dependence-independence (measured on a Portable Rod and Frame Test) and the acquisition of a kayak skill was examined. Undergraduates (6 men, 11 women; M age=21.6 yr., SD=3.2) who had no previous kayaking experience participated. Participants completed a structured teaching session (2 hr.) designed to develop three key subskills necessary for the kayak roll. Number of trials taken to consistently perform the underwater orientation and paddle movement subskills and duration of practice taken to develop the upper/lower body separation subskill as well as participants' ability to complete the roll were assessed. Field independence was associated with better performance of subskills and skill acquisition tests. Learners with greater field independence may have an advantage when acquiring sport skills that require cognitive restructuring and a strong reliance on kinesthetic and proprioceptive feedback.

Recreational diving: Re-evaluation of task, environment, and equipment definitions

Recreational diving has developed extensively over the years, becoming a popular sport and leisure activity, attracting millions of people around the world. A questionnaire aiming to identify problematic stages during recreational diving and to map the relative importance of the diving equipment features was distributed among divers of different genders, ages, certification, and professional experience (N=130). It was found that the most problematic stages for recreational divers (out of 32 tasks) were on-land activities and transitional phases between water and terrestrial interfaces: carrying equipment on shore, underwater orientation, exiting from water to boat and reef, surface swimming, and donning the wetsuit. Safety/reliability, individual adjustment, performance, and simplicity were rated the most important features for diving equipment, while design/style and brand name were rated the least. We suggest that redefinition of the task, equipment, and environment according to the current profile of recreational divers will increase pleasure, reduce fatigue and related diving accidents, improve safety, and increase the number of dedicated active divers.

Electric fishes as a biological prototype of new technology

Physics, mathematics, and chemistry were traditionally considered basic for the development of new technology. They suggested solutions for achieving maximum characteristics, such as maximum range, speed, strength, and precision, which were especially important in the military sphere. However, in recent years, new technology developers have increasingly often been addressing biological sciences. This paper considers a bionic approach to short-range underwater location, orientation, and communication equipment. This topic has been being researched at the Severtsov Institute of Ecology and Evolution, RAS, for more than 30 years.

Breathing and orientation underwater in swimming pool: Effects of age, practice, and duration of an aquatic stimulation program in babies and infants


 Nowadays there are not many investigation results about infant and baby's motor behavior in the aquatic environment. The present study seeks to describe it before the 40 months of age and to examine the relationship between the motor acquisitions and the chronological age, time of practice and program duration. A system of categories and sub-categories of baby's motor behavior was developed for two dimensions: breathing control and underwater orientation. This system was validated with obtained values of 96% of objectivity and 100% of consistency. Then, 101 babies and infants were evaluated between 3 and 40 months of age, some of them in different moments, in a total of 216 observations (N=216). Breathing control and underwater orientation skills were strongly correlated with chronological age, time of practice and program duration. All the correlations were positive with 0.75-0.86% and significant (ρâ‰-0.01), meaning that as age, time of practice or program duration increases, the breathing control and underwater orientation skills showed clear improvement. Chronological ages for developmental steps in aquatic environment were identified. Results are discussed within a maturation-stimulation theoretical framework. The evaluation tool that was proposed and validated is ready for use and can be applied in other research settings.

Research for enhancing the precision of asymmetrical SBL system for any vessels

The SBL system (Short Baseline System) is usually utilized by offshore working vessels when performing its underwater orientation task so as to facilitate the exploitation of abundant benthal resources, therefore, the precise distance between the vessel and underwater targets for SBL system's estimation module are highly emphasized. However, hydrological data cited in the SBL system's estimation module is not real-time information and is difficult to accurately measure, which causes the calculation errors. Studies with regard to symmetrical SBL system are carried out by most of the researchers these days, yet research in this text shows the advantage to the asymmetrical SBL system's sensor on the vessel's bottom to be installed at discretion to measure and calculate the position. In addition to the locus equation used in the traditional position calculation, Haussiam Elimination, Cramer's rule, 3D geometry relation theory as well as substitution corrections applied to this asymmetrical SBL system to educe the correction for relative geometrical position between the underwater beacon and the sensor on the ship bottom. Through numeric simulation analysis, this SBL system is proved to be a high precision acoustic positioning system based on its quick correction and high precision position calculated by the asymmetrical SBL system established in this study.

Why pinnipeds don't echolocate.

Odontocete cetaceans have evolved a highly advanced system of active biosonar. It has been hypothesized that other groups of marine animals, such as the pinnipeds, possess analogous sound production, reception, and processing mechanisms that allow for underwater orientation using active echolocation. Despite sporadic investigation over the past 30 years, the accumulated evidence in favor of the pinniped echolocation hypothesis is unconvincing. We argue that an advanced echolocation system is unlikely to have evolved in pinnipeds primarily because of constraints imposed by the obligate amphibious functioning of the pinniped auditory system. As a result of these constraints, pinnipeds have not developed highly acute, aquatic, high frequency sound production or reception systems required for underwater echolocation. Instead, it appears that pinnipeds have evolved enhanced visual, tactile, and passive listening skills. The evolutionary refinement of alternative sensory systems allows pinnipeds to effectively forage, navigate, and avoid predators under water despite the lack of active biosonar capabilities.

Analyse d’image pour l’évaluation de l’exposition de la côte à l’action des vagues

A method of analysis was developed to estimate wind‐induced wave heights in the coastal zone. The analysis is based on a digital bathymetry model in raster format. The model uses wind characteristics such as direction, velocity, and fetch. In addition, underwater terrain slope magnitude and orientation, and water depth are used in the computation of the model to estimate wave heights. Two analyses are shown, taking into account waves built from short fetch wind and indefinite fetch wind. The analysis was applied to Hare Bay in northern Newfoundland. First, we take into account a northerly wind of 6.9 ms−1 where the fetch is 19 km or less. The estimated wave heights vary between 0 and 0.5 m. With the second application, we considered an indefinite ESE fetch wind of 17.8 ms−1. In this case, the wave heights resulting from the application of the model vary between 0 and 11.8 m. We compared the modelling results based on ESE wind and the wave energy derived through visual analysis. Relationships were identified between the wave height classes and the wave energy categories.

Mother–pup reunions in harp seals, Phoca groenlandica: cues for the relocation of pups

This study was designed to examine how female harp seals (Phoca groenlandica) solve the orientation problems they face when returning to their pups from the water in a pack-ice environment. Data were collected during the breeding seasons of 1992 and 1993 in the Gulf of St. Lawrence, Canada. During 31 h of observations, 73 returns of females were documented. Most return paths of females from the water originated at the access point closest to their pup (88%), indicating good underwater orientation capabilities. The mean path length was 1.3 ± 2.2 times the length of a direct line between the water access point and the pup, and most females were clearly oriented toward their pup upon leaving the water. Most return paths (84%) terminated in a nursing session with the pup. Prior to nursing, naso–naso contact was made by the mother–pup pair. Only 26% of return paths were directed toward a calling pup, the rest were spontaneously performed to a silent, unmoving pup. The mean duration of calling prior to the appearance of the female was 7.3 ± 7.2 min (N = 18). Mothers returning to a vocalizing pup did not have more direct return paths than those returning to a silent pup (Mann–Whitney U test, U = 422, P = 0.19). Although pups were remarkably sedentary in the absence of their mothers, approximately half of females returning to their pup (32/73) were approached by it. Only 7% of paths (5/73) of females involved contact with a foreign pup. Likewise, pups rarely approached females other than their mother. Females were able to return directly to sleeping, silent (or dead) pups that were not visible from the origin of the path and were able to return to locations where they had last left the pup without the pup itself acting as a stimulus. Thus, it appears that harp seal mothers use multimodal sensory cues to return to their pups in the pack-ice environment. At long distances spatial information appears to be of primary importance and can be used exclusively by females to return to specific positions on the ice. Visual and auditory cues emitted by pups may ease the task of relocation, although they must be considered of secondary importance. Pups appear to recognise their mothers at a distance. At close range, olfactory cues provide the definitive means of individual identification within mother–pup pairs.

The use of celestial cues in the offshore escape response of the shrimp,palaemonetes vulgaris

The involvement of celestial cues in y‐axis orientation was studied for the shrimp Palaemonetes vulgaris. Underwater orientation was monitored with a video system in an outside circular arena which excluded all but celestial cues. Shrimp were collected from three shorelines having different offshore directions. The shrimp had an escape response in which they oriented in a direction similar to the offshore direction of their home shoreline at different times of day when (1) the sky was clear, (2) the sun was apparent through a cloud filled sky, and (3) the sun was obscured leaving blue sky. If the sun was diffused and repositioned with a mirror, the shrimp reoriented relative to the new position of the sun. Under completely cloudy skies, unimodal orientation ceased. These results indicate that the shrimp's offshore escape response is mediated by sun compass orientation. The blue sky contains orientation information for this y‐axis orientation, but the sun is the stronger cue.

UNDERWATER ORIENTATION IN THE SAND FIDDLER CRAB,UCA PUGILATOR

The semi-terrestrial sand fiddler crab, Uca pugilator, occasionally is forced by avian and mammalian predators to go into the water where it becomes vulnerable to aquatic predators. Therefore, it would be adaptive for Uca to possess some means of detecting the direction of the shore and its burrow while submerged. Using crabs from Florida and Long Island, New York, the identity of the cues used in underwater orientation and the possible hierarchial arrangement of these cues were ascertained.Under various cue regimes, the crabs were individually observed in a long narrow tank that allowed the crabs to proceed either toward shore or away from it. The potential cues for shoreward orientation which were available to the submerged crab were celestial cues, landmarks, and gradient cues (hydrostatic pressure, light wavelength, light intensity and substrate slope). Each cue was isolated and then tested for its effectiveness in orientation. It was next presented to the crabs in a conflicting configuration with oth...