Introduction: Magnetic North, Iron and Grace

2017 ◽  
pp. 1-8
Author(s):  
Ellen Hinsey
Keyword(s):  
Magnetic North

Subsurface fracture surveys using a borehole television camera and acoustic televiewer

1987 ◽  
Vol 24 (4) ◽  
pp. 499-508 ◽  
Author(s):  
J. S. O. Lau ◽  
L. F. Auger ◽  
J. G. Bisson
Keyword(s):  
Rapid Assessment ◽  
Cost Effective ◽  
Fracture Aperture ◽  
Computer Data ◽  
Fracture Characteristics ◽  
Television Camera ◽  
Strip Chart ◽  
Data Record ◽  
Magnetic North ◽  
Apparent Orientation

Borehole television survey and acoustic televiewer logging provide rapid, cost-effective, and accurate methods of surveying fractures and their characteristics within boreholes varying in diameter from 7.6 to 15.3 cm. In the television survey, a camera probe is used to inspect the borehole walls. Measurements of location, orientation, infilling width, and aperture of fractures are made on the television screen and recorded on computer data record sheets. All observations are recorded on video cassette tapes. With the acoustic televiewer, oriented images of fractures in the borehole walls are recorded on a strip–chart log and also on video cassette tapes. The images are displayed as if the walls were split vertically along magnetic north and spread out horizontally. Measurements of fracture characteristics are made on the strip–chart log, using a digitizing table and a microcomputer, and the data recorded on floppy diskettes. In both surveys, an inclined fracture is displayed as a sinusoidal curve, from which the apparent orientation of the fracture can be measured. Once the borehole orientation is known, the true orientation of the fracture can be computed from its apparent orientation. Computer analysis of the fracture data, provides a rapid assessment of fracture occurrence, fracture aperture, and statistically significant concentrations of fracture orientations. Key words: borehole, television survey, acoustic televiewer logging, fractures, distribution, orientation, aperture.

scholarly journals Impact of a Vibrotactile Belt on Emotionally Challenging Everyday Situations of the Blind

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7384
Author(s):  
Charlotte Brandebusemeyer ◽  
Anna Ricarda Luther ◽  
Sabine U. König ◽  
Peter König ◽  
Silke M. Kärcher
Keyword(s):  
Emotional Impact ◽  
Vibrotactile Stimulation ◽  
Angular Rotation ◽  
Straight Line ◽  
Before And After ◽  
Fixed Reference ◽  
Behavioural Experiments ◽  
Triangle Completion ◽  
Subjective Discomfort ◽  
Magnetic North

Spatial orientation and navigation depend primarily on vision. Blind people lack this critical source of information. To facilitate wayfinding and to increase the feeling of safety for these people, the “feelSpace belt” was developed. The belt signals magnetic north as a fixed reference frame via vibrotactile stimulation. This study investigates the effect of the belt on typical orientation and navigation tasks and evaluates the emotional impact. Eleven blind subjects wore the belt daily for seven weeks. Before, during and after the study period, they filled in questionnaires to document their experiences. A small sub-group of the subjects took part in behavioural experiments before and after four weeks of training, i.e., a straight-line walking task to evaluate the belt’s effect on keeping a straight heading, an angular rotation task to examine effects on egocentric orientation, and a triangle completion navigation task to test the ability to take shortcuts. The belt reduced subjective discomfort and increased confidence during navigation. Additionally, the participants felt safer wearing the belt in various outdoor situations. Furthermore, the behavioural tasks point towards an intuitive comprehension of the belt. Altogether, the blind participants benefited from the vibrotactile belt as an assistive technology in challenging everyday situations.

scholarly journals Laboratory studies of homing orientation in the eastern red-spotted newt, Notophthalmus viridescens

1987 ◽  
Vol 131 (1) ◽  
pp. 215-229 ◽  
Author(s):  
J. B. Phillips
Keyword(s):  
Water Temperature ◽  
Laboratory Tests ◽  
Notophthalmus Viridescens ◽  
Magnetic Orientation ◽  
Laboratory Studies ◽  
Navigational System ◽  
South Axis ◽  
Magnetic North ◽  
Migratory Period ◽  
East West

The orientation behaviour of adult male eastern red-spotted newts (Notophthalmus viridescens) was studied in laboratory tests. Newts were collected from ponds located 10–30 km from the laboratory, and housed in water-filled, all-glass aquaria located in a greenhouse or outdoors adjacent to the laboratory building. The aquaria were aligned on the magnetic north-south axis. Newts were tested in a dry, enclosed arena in four magnetic fields: the ambient magnetic field (magnetic north at North) and three altered fields (magnetic north rotated to East, West or South). Newts tested during January-March exhibited weak bimodal magnetic orientation along the axis of the holding tank. However, during the spring migratory period (April until early May), the bimodal response shifted to coincide with the direction of the pond from which the newts had been collected. Much stronger unimodal orientation was elicited by elevating the water temperature to 33–34 degrees C immediately prior to testing. If newts were held in a training tank with an artificial shoreline at one end and exposed to elevation of water temperature after several days of stable water temperatures, they exhibited unimodal shoreward orientation and did not show the seasonal switch to homing behaviour observed in the earlier tests. If, however, the elevation of water temperature followed a period of fluctuating water temperature (over a 20 degrees C range), the newts exhibited strong unimodal orientation in the direction of the pond from which they had been collected. These results suggest that newts possess a navigational system that enables them to home from distances in excess of 20 km. Moreover, these experiments provide the first opportunity to examine the sensory basis of navigational ability in any animal under controlled laboratory conditions.

scholarly journals Semiautomatic sun shots with the WIDIF DIflux

2017 ◽  
Vol 6 (2) ◽  
pp. 257-261
Author(s):  
Jean L. Rasson ◽  
Olivier Hendrickx ◽  
Jean-Luc Marin
Keyword(s):  
Gps Receiver ◽  
Magnetic Declination ◽  
Declination Angle ◽  
Magnetic North

Abstract. The determination of magnetic declination angle entails finding two directions: geographic north and magnetic north. This paper deals with the former. The known way to do it by using the sun's calculable orientation in the sky is improved by using a device based on a WIDIF DIflux theodolite and split photocells positioned on its telescope ocular. Given the WIDIF accurate timing and location provided by the onboard GPS receiver, an astronomical computation can be effected to accurately and quickly determine the sun's azimuth and an auxiliary mark's azimuth. The precise sun's crossing of the split photocell, amplified by the telescope's magnification, allows azimuth accuracies of a few seconds of arc.

scholarly journals Possible influence of variations in the geomagnetic field on migration paths of snow buntings

2019 ◽  
Vol 19 (2) ◽  
pp. 195-201
Author(s):  
Chris M. Hall ◽  
Magnar G. Johnsen
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Flight Time ◽  
Short Term ◽  
Breeding Grounds ◽  
Declining Populations ◽  
Plectrophenax Nivalis ◽  
The Individual ◽  
Magnetic North ◽  
The Magnetic Field

AbstractA hypothesis is proposed wherein changes in the Earth's magnetic field affect the migratory paths of snow buntings (Plectrophenax nivalis), and in particular from wintering grounds in the Russian/Ukrainian steppes to breeding grounds on Svalbard and with a typical stopover in Finnmark in northern Norway. If one were to assume ignorance of the secular movement of the magnetic north pole approximately 1500 km northwards between 1908 and 2020, the magnetoreceptor contribution to snow buntings' navigation would result in winter-to-summer migratory paths progressively further to the East. In turn, this could be a contributing factor to declining populations in Finnmark and favouring a more frequent flightpath over the Kola Peninsula. On the other hand, short-term perturbations in the magnetic field (i.e. induced by solar activity) and therefore existing for a relatively small proportion of the flight time (if at all) for the individual migrations legs seem unlikely to influence the stopover locations significantly. Even so, these space-weather induced variations cannot be disregarded, particularly for success in reaching Svalbard.

Magnetische Monopole in vereinheitlichten Eichtheorien

1986 ◽  
Vol 41 (6) ◽  
pp. 777-787
Author(s):  
Eckehard W. Mielke
Keyword(s):  
Elementary Particle ◽  
Particle Physics ◽  
Detection Methods ◽  
Elementary Particle Physics ◽  
Gauge Models ◽  
Empirical Success ◽  
Long Time ◽  
The Impact ◽  
Magnetic North

Although refuted for a long time as a monstrosity, today’s concepts in elementary particle physics necessitate it on theoretical grounds: The existence of isolated elementary magnetic north- or south poles. If compared with a proton, the mass of such a monopole is estimated to be gigantic; comparable to that of an amoeba. Under the impact of the empirical success of unified gauge models, the search for monopoles has been steadily enforced with the aid of new detection methods.

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