scholarly journals CHARACTERISTICS OF GEOPHYSICAL FIELDS ON THE ELBRUS AND KAZBEK

2014 ◽  
Author(s):  
В.Б. Заалишвили ◽  
Н.И. Невская ◽  
Л.Н. Невский ◽  
А.Г. Шемпелев
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Geological Structure ◽  
Regional Level ◽  
The Caucasus ◽  
Caucasus Region ◽  
Gravity Fields ◽  
Central Caucasus ◽  
Local Anomalies ◽  
The Magnetic Field

В статье рассмотрены особенности геологического строения Эльбруса и Казбека. Одной из особен- ностей поля силы тяжести Кавказа является наличие для районов Приэльбрусья и Чегемского нагорья самых минимальных значений в Большекавказском регионе. Относительно положительные значения гра- витационного поля Казбекского района, определяются приповерхностным слоем с избыточной плотно- стью 0,15х103 кгм3 верхняя и нижняя границы которого находятся на глубинах порядка 0,5 и 4,5 км. Зона Главного хребта Центрального Кавказа является в региональном плане областью пониженных значений магнитного поля, которое осложнено локальными знакопеременными аномалиями. In the article the features of geological structure of Elbrus and Kazbek are examined. One of the features of the gravity fields of the Caucasus is the availability for areas of Elbrus and Chegem Highlands most minimum values in the big Caucasus region. The positive values of the gravitational field of the Kazbek district, are determined by the surface layer with excessive densities of 0,15х103 кgм3 the top and bottom borders are at depths of about 0.5 and 4.5 km. Area of the main ridge of the Central Caucasus has at the regional level the lower values of the magnetic field, which is complicated by alternating local anomalies

THE USE OF POISSON’S RELATION FOR THE EXTRACTION OF PSEUDOTOTAL MAGNETIC FIELD INTENSITY FROM GRAVITY OBSERVATIONS

Geophysics ◽  
1971 ◽  
Vol 36 (3) ◽  
pp. 605-608 ◽  
Author(s):  
Edwin S. Robinson
Keyword(s):  
Magnetic Field ◽  
Gravity Field ◽  
Field Data ◽  
Field Potential ◽  
Geological Structure ◽  
Common Source ◽  
Uniform Density ◽  
Practical Applications ◽  
Uniform Magnetization ◽  
Gravity Fields

Investigation of geological structure by gravimetric and magnetic field surveys requires consideration of relationships between gravity anomaly and magnetic anomaly generating sources. The possibility of using Poisson’s Relation to examine magnetic and gravity fields related to a common source is intriguing. This relation is expressed as follows: [Formula: see text] (1) where A (x, y, z) is the magnetic field potential and U (x, y, z) is the gravity field potential at a point in space due to a source of uniform density ρ and uniform magnetization I in the direction α. This expression has been used to derive magnetic anomalies over idealized forms (Nettleton, 1940) and, by Baranov (1957), to extract pseudogravity fields from magnetic field data. The purpose of this paper is to develop an expression for extracting a pseudomagnetic field from gravity field data and to examine the practical applications of this expression.

THE MAGNETIC FIELD AT THE SURFACE OF A STRATIFIED FLAT CONDUCTOR IN THE FIELD OF PLANE WAVES WITH APPLICATION TO GEOPHYSICS

1962 ◽  
Vol 40 (11) ◽  
pp. 1583-1592 ◽  
Author(s):  
H. W. Dosso
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Electromagnetic Waves ◽  
Plane Waves ◽  
Geomagnetic Variations ◽  
Wide Range ◽  
The Magnetic Field

The problem of plane electromagnetic waves incident on a stratified flat conductor is considered. Expressions for the amplitude and phase of the components of the resultant magnetic field at the surface of the conductor are obtained and evaluated for a wide range of frequencies, conductivities, surface layer depths, and angles of incidence. The frequencies f = 10−3 to 103 cycles/sec and the conductivities σ = 10−11 to 10−16 emu considered are of interest in studying geomagnetic variations.

scholarly journals Modelling of magnetic field and flux in objects having surface-hardening and transition layer

2018 ◽  
Vol 224 ◽  
pp. 03015
Author(s):  
Vladimir Kostin ◽  
Olga Vasilenko ◽  
Alexander Byzov
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Transition Layer ◽  
Surface Hardening ◽  
Layer Structure ◽  
Hardened Layer ◽  
Element Simulation ◽  
Object Of Control ◽  
The Magnetic Field ◽  
Hardened Surface

A finite element simulation of the distribution of the magnetic field and flux in locally magnetized steel objects subjected to surface hardening and having after hardening a three-layer structure: a hardened surface layer, a transition layer, an unstressed core; has been conducted. Magnetization of the tested object was conducted using a U-shaped electromagnet. As a result, pictures of the distribution of the magnetic field in the monitoring object were obtained. The values of induction depending on the depth of the hardened layer for a fixed transition layer at different points of space relative to the surface of the object of control are obtained.

A downhole magnetometric resistivity technique for electrical sounding beneath a conductive surface layer

Geophysics ◽  
1988 ◽  
Vol 53 (4) ◽  
pp. 528-536 ◽  
Author(s):  
R. N. Edwards
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Magnetic Fields ◽  
Current Source ◽  
Diagnostic Ratios ◽  
Sea Floor ◽  
Earth Resistivity ◽  
Conductive Surface ◽  
Electrical Sounding ◽  
The Magnetic Field

The magnetometric resistivity (MMR) method has not been used systematically for vertical electrical sounding because surficial measurements of the magnetic field caused by static current flow from a point source of current at the surface are independent of the form of the variation of earth resistivity with depth. However, data obtained from an adaptation of the MMR method in which the ratio of the magnetic fields below and above a known conductive surface layer is measured as a function of the horizontal range from the current source can be inverted to obtain the unknown resistivity of deeper material. The practical limitation is that the integrated conductivity of the surface layer must not be much smaller than the integrated conductivity of the unknown zone in order to observe diagnostic ratios significantly different from unity. The expressions derived for the magnetic‐field ratio and for the sensitivity of the ratio to changes in the resistivity of a plane‐layered unknown zone are closed‐form inverse Hankel transforms. The transforms are evaluated analytically for a model of constant, uniform resistivity. One possible geotechnical application of the method is the detection of offshore, resistive permafrost beneath the shallow Beaufort Sea. A theoretical design study in which ratios of the magnetic fields at the bottom and top of the sea are synthesized and the sensitivity of those ratios to changes in sea‐floor resistivity is determined as a function of range and depth, respectively, reveals that the resistivity of a permafrost zone 50 m thick buried 20 m below the sea floor can be identified. The maximum range needed is of the order of 200 m, which appears to be smaller than the maximum spacing required for a Schlumberger sounding to yield similar information.

scholarly journals Karyotype characteristics and chromosomal polymorphism of Chironomus “annularius” sensu Strenzke (1959) (Diptera, Chironomidae) from the Caucasus region

2018 ◽  
Vol 12 (3) ◽  
pp. 267-284
Author(s):  
Mukhamed Kh. Karmokov
Keyword(s):  
Principal Component ◽  
Chromosomal Polymorphism ◽  
Genetic Distances ◽  
Geographic Proximity ◽  
South Caucasus ◽  
The Caucasus ◽  
Caucasus Region ◽  
Central Caucasus ◽  
Almost All ◽  
Single Cluster

The study presents data on the karyotype characteristics and features of chromosomal polymorphism of Chironomus “annularius” sensu Strenzke (1959) (Diptera, Chironomidae) from three populations of the Caucasus region (South and Central Caucasus, and Eastern Ciscaucasia). We found 17 banding sequences in the Caucasian populations. We observed inversion polymorphism in almost all chromosome arms except for arm G. The genetic distances between all the studied populations of Ch. “annularius” were calculated using Nei criteria (1972). In spite of relative geographic proximity, the genetic distances between populations of the Caucasus are quite large, and they do not form a single cluster of Caucasian populations. The population of the South Caucasus goes to the European cluster, the population of the Central Caucasus goes to the Asian cluster and the population of Eastern Ciscaucasia does not belong to any of the outlined clusters. Principal component analysis (PCA) shows a similar picture. Two of the Caucasian populations do not follow Hardy-Weinberg expectation, there being a marked deficiency of heterozygotes in arms A, B and C, arguably, due to negative selection of heterozygotes or founder effect. All the obtained data are indicative of the complex genetic structure of Caucasian populations of Ch. “annularius” and total complexity microevolution processes occurring in the Caucasus region.

scholarly journals EVALUATION OF METALLOGENIC FACTORS ON THE BASIS OF DIGITIZING AND RE-INTERPRETATION OF DATA ANALOG AEROMAGNETIC IMAGES OF THE EXAMPLE MALKA-MULTINSKOGO ORE UNIT (NORTH CAUCASUS)

2018 ◽  
Author(s):  
С.Г. Парада
Keyword(s):  
Magnetic Field ◽  
Geological Structure ◽  
Local Magnetic Field ◽  
North Caucasus ◽  
Aeromagnetic Survey ◽  
North East ◽  
The North ◽  
Ore Bodies ◽  
The Right ◽  
Local Anomalies

Осуществлена оцифровка данных аналоговой аэромагнитной съемки конца 60-х годов прошлого столетия, что дало возможность применить цифровые методы обработки больших массивов данных на основе ГИС-технологий. Решались две задачи – получение числового массива, описывающего ∆Та по исследуемой площади и выделение разномасштабных аномалий поля ∆Та (локальных, площадных и региональных), обусловленных геологическими объектами, представляющими металлогенические факторы (рудогенерирующие интрузивные тела, рудоподводящие, рудораспределяющие и рудолокализующие разломы, признаки литологического контроля оруденения). В итоге выделены аномалии регионального и площадного (среднемасштабного) фона магнитного поля и локальные аномалии. Это позволило уточнить геологическое строение и металлогенические перспективы территории. В частности, по особенностям распространения локальных аномалий и площадного фона выявлено и прослежено продолжение Малкинского гранитоидного массива под толщей метаморфических сланцев далее на северо-восток, установлено, что наиболее перспективная часть Малка-Муштинского рудного узла располагается в кровле Малкинского гранитного массива, в месте ее резкого погружения по крутому рудоподводящему разлому северо-западного простирания. Выделение локальных аномалий магнитного поля позволило выявить не выходящие на поверхность (слепые) тела габбро-диабазов и габбро-диоритов Хасаутского интрузивного комплекса на правобережной части Малка-Муштинского рудного узла, что расширяет перспективы обнаружения слепых рудных тел. Digitization of data of analog aeromagnetic survey of the late 60-ies of the last century was carried out, which made it possible to apply digital methods for processing large amounts of data on the basis of GIS technologies. We focused on two tasks – getting numeric array describing ∆of The study area and the allocation of multi-scale anomaly field ∆TA (local, areal and regional), due to geological features that represent metallogenic factors (rodegenerative Intrusive body, retopologise, rodorazresheniye and ore localizing faults, signs of lithological control of mineralization). As a result, the anomalies of the regional and area (medium-scale) background of the magnetic field and local anomalies are identified. This allowed to clarify the geological structure and metallogenic prospects of the territory. In particular, by the peculiarities of local anomalies and area background distribution, the continuation of the Malkin granitoid massif under the thickness of metamorphic shales further to the North-East was revealed and traced, it was found that the most promising part of the Malka-Mushta ore node is located in the roof of the Malka granite massif, at the place of its sharp immersion in the steep ore-producing fault of the North-Western strike. The isolation of local magnetic field anomalies allowed to reveal non-surface (blind) bodies of gabbro-diabases and gabbro-diorites of the Khasaut Intrusive complex on the right Bank of the Malka-Mushta ore node, which extends the prospects for the detection of blind ore bodies.

scholarly journals Практика омагничивания в постоянном магнитном поле термически обработанных быстрорежущих сталей

2021 ◽  
Vol 70 (2) ◽  
pp. 68-70
Author(s):  
В.Н. Пустовойт ◽  
Ю.В. Долгачев ◽  
Д.А. Сахно
Keyword(s):  
Magnetic Field ◽  
Surface Layer ◽  
Domain Structure ◽  
High Speed ◽  
High Speed Steel ◽  
Steel R6m5 ◽  
Hardening Effect ◽  
The Magnetic Field

The article is devoted to the processing of high-speed steel R6M5 in a magnetic field. Attention is paid to the presence of a domain structure after magnetization. Studies of microhardness after magnetization are carried out. The reversibility of the hardening effect after removal of the magnetic field is determined. The influence of finishing operations of surface layer processing is established.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Sign in / Sign up

Export Citation Format

Share Document