Готові списки джерел за темами / Weakening of the geomagnetic field / Дисертації
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Weakening of the geomagnetic field.

Дисертації з теми "Weakening of the geomagnetic field"

Автор: Grafiati
Опубліковано: 30 травня 2022
Оновлено: 31 травня 2022

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся з топ-50 дисертацій для дослідження на тему "Weakening of the geomagnetic field".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.

1

Грецких, Светлана Владимировна. "Ослабление статического геомагнитного поля ферромагнитными элементами домов". Thesis, Государственное учреждение "Институт технических проблем магнетизма НАН Украины", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21435.

Повний текст джерела
Анотація:
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.09.05 – теоретическая электротехника. – Национальный технический университет "Харьковский политехнический институт", Харьков, 2016. Диссертация посвящена математическому моделированию явления ослабления статического геомагнитного поля (ГМП) в помещениях жилых домов и разработке рекомендаций по методам его нормализации до безопасного уровня. Полученные в диссертации результаты в совокупности составляют существенный вклад в решение научно-прикладной задачи теоретической электротехники по моделированию явления ослабления ГМП стальными ферромагнитными элементами конструкций домов и разработки рекомендаций по методам нормализации ГМП в помещениях до безопасного для людей уровня. Основные результаты выполненных в диссертации исследований и практических разработок использованы при выполнении тематического плана ГУ "ИТПМ НАН Украины", в Институте гигиены и медицинской экологии им. А. Н. Марзеева НАМН Украины при разработке "Государственных санитарных правил и норм защиты населения от влияния электромагнитных излучений", при проектировании и строительстве в г. Харькове современных каркасно-монолитных жилых домов с безопасными условиями проживания (ООО "АВУАР"). Результаты работы рекомендованы к применению научным и промышленным учреждениям и предприятиям, выполняющим разработку методов и средств моделирования, расчета и нормализации статического ГМП в жилых домах, проектирующим современные жилые дома с безопасными условиями проживания по магнитному полю.
Thesis for scientific degree of candidate of technical sciences, specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to mathematical modeling of the phenomenon of weakening of the static geomagnetic field (GMF) in residential homes and to the development of recommendations on how to normalize it to a safe level. The modeling of weakening of the GMF was performed with the help of the equivalent charges method. The cylindrical ferromagnetic column was taken as an example. In the framework of this technique the problem of calculation of the GMF’s induction weakened by extended ferromagnetic elements was solved. The physical parameters of the ferromagnetic column which effect the weakening of GMF are determined. The conditions under which GMF is reduced to the safety level are also determined. This is due to the changes of the GMF’s geometry and reducing of initial magnetic permeability of its material. The Arcadiev method of the effective magnetic permeability for modeling of magneticfield of reinforced concrete columns and intermediate floors was developed. The numerical modeling of static GMF in premises of houses with reinforced concrete structures was performed. The numerical results were experimentally confirmed. The recommendations for normalizing of GMF for creating safe and comfortable living conditions are given. These recommendations should be taken into account in designing modern premises of houses.
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Грецьких, Світлана Володимирівна. "Ослаблення статичного геомагнітного поля феромагнітними елементами будинків". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21433.

Повний текст джерела
Анотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.05 – теоретична електротехніка. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2016. Дисертація присвячена математичному моделюванню явища ослаблення статичного геомагнітного поля (ГМП) в приміщеннях житлових будинків та розробці рекомендацій з методів його нормалізації до безпечного рівня. На прикладі циліндричної феромагнітної колони проведено моделювання ослаблення ГМП за допомогою методу еквівалентних (фіктивних) магнітних зарядів та розв’язано задачу розрахунку індукції ГМП, ослабленого протяжними феромагнітними елементами. Визначенні фізичні параметри феромагнітної колони, що впливають на інтенсивність ослаблення ГМП поблизу її поверхні, та умови зменшення до безпечного рівня інтенсивності ослаблення ГМП за рахунок зміни геометрії колони та зменшення початкової магнітної проникності її матеріалу. Здійснено розвиток методу ефективної магнітної проникності Аркадьєва для моделювання магнітного поля залізобетонних колон та міжповерхових перекриттів, армованих сталевим металопрокатом, та виконане чисельне моделювання інтенсивності ослаблення статичного ГМП в приміщеннях житлових будинків з несучими залізобетонними конструкціями і його верифікацію на основі результатів експерименту. Розроблені рекомендації з методів нормалізації ГМП при проектуванні сучасних житлових будинків для створення безпечних та комфортних умов проживання населення за статичним ГМП.
Thesis for scientific degree of candidate of technical sciences, specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to mathematical modeling of the phenomenon of weakening of the static geomagnetic field (GMF) in residential homes and to the development of recommendations on how to normalize it to a safe level. The modeling of weakening of the GMF was performed with the help of the equivalent charges method. The cylindrical ferromagnetic column was taken as an example. In the framework of this technique the problem of calculation of the GMF’s induction weakened by extended ferromagnetic elements was solved. The physical parameters of the ferromagnetic column which effect the weakening of GMF are determined. The conditions under which GMF is reduced to the safety level are also determined. This is due to the changes of the GMF’s geometry and reducing of initial magnetic permeability of its material. The Arcadiev method of the effective magnetic permeability for modeling of magneticfield of reinforced concrete columns and intermediate floors was developed. The numerical modeling of static GMF in premises of houses with reinforced concrete structures was performed. The numerical results were experimentally confirmed. The recommendations for normalizing of GMF for creating safe and comfortable living conditions are given. These recommendations should be taken into account in designing modern premises of houses.
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Hutcheson, Kenneth Andrew. "Geomagnetic field modelling." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385503.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Thorsen, Kjetil. "Mathematical Model of the Geomagnetic Field." Thesis, Norwegian University of Science and Technology, Department of Mathematical Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9329.

Повний текст джерела
Анотація:

First comes a description of a mathematical model of the geomagnetic field. Then some discussion of the classical non-uniqueness results of Backus. Further we look at more recent results concerning reconstruction of the geomagnetic field from intensity and the normal component of the field. New stability estimate for this reconstruction is obtained.

Стилі APA, Harvard, Vancouver, ISO та ін.
5

Ryan, David Alexander. "The long term behaviour of the geomagnetic field." Thesis, University of Newcastle upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519467.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Livermore, R. A. "The time-average geomagnetic field since the late Palaeozoic." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355532.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Filippi, Enrico <1983&gt. "Turbulent Diffusion of the Geomagnetic Field and Dynamo Theories." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7471/.

Повний текст джерела
Анотація:
The thesis deals with the Dynamo Theories of the Earth’s Magnetic Field and mainly deepens the turbulence phenomena in the fluid Earth’s core. Indeed, we think that these phenomena are very important to understand the recent decay of the geomagnetic field. The thesis concerns also the dynamics of the outer core and some very rapid changes of the geomagnetic field observed in the Earth’s surface and some aspects regarding the (likely) isotropic turbulence in the Magnetohydrodynamics. These topics are related to the Dynamo Theories and could be useful to investigate the geomagnetic field trends.
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Finnman, Jonas, and Erik Eketorp. "Design and Manufacturing of IPM Synchronous Motor for Field Weakening Operation." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-128511.

Повний текст джерела
Анотація:
Rotor designs for permanent magnet synchronous machines suitable for field weakening operation have been evaluated for use with an existing drive system. The designs have been simulated with the FEM-based software Finite Element Method Magnetics (FEMM). Based on the results two different internal magnet rotors have been constructed and tested. Both designs significantly improved the speed range while maintaining or improving magnet utilisation. The implementation of field weakening algorithms in drive electronics is complex and need thorough optimisation for stable operation. Internal permanent magnet rotors are a good alternative to surface mounted designs and enables a wider speed range through improved field weakening capabilities.
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Antunes, Fernando Luiz Marcelo. "A microprocessor-controlled DC servo-drive with spill-over field weakening." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/33224.

Повний текст джерела
Анотація:
The thesis presents a speed-control scheme for a separately-excited DC motor using a microprocessor. The control strategy incorporates both armature-voltage control and spill-over field weakening. The armature voltage is controlled in closed loop using a lead term in series with an integral term. The analogue Lead-Integral (LI) controller parameters were obtained and optimised by observing the system time response in successive digital simulations. The parameters determined provide the motor with a fast response and minimum speed overshoot during transient operations. The analogue LI controller was emulated to form a digital filter using the bilinear transformation and implemented in a 16-bit microprocessor using floating point arithmetic.
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Zhang, Yuan. "Sensorless Vector Control and Field Weakening Operation of Permanent Magnet Synchronous Machines." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291219704.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
11

McArdle, Nicholas John. "Long term variation in geomagnetic field intensity and terrestrial planet development." Thesis, University of Liverpool, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569142.

Повний текст джерела
Анотація:
Knowledge of the intensity of the Earth's magnetic field throughout geological time can deliver a wealth of information regarding the development of the planet. The nature of the geomagnetic field is dependent on processes that occur deep in the Earth's core. By analysing long period changes in geomagnetic field intensity inferences can be made about conditions in the Earth's interior far back into Earth history. The microwave palaeointensity technique is a relatively recent addition to palaeomagnetic investigation. High-frequency microwaves, which are resonant with the constituent magnetic system of a rock, are used to isolate and progressively remove the magnetisation of samples acquired at the time of formation in a controlled manner. By exciting the magnetic system directly, thermal-type experiments can be conducted, whilst minimising the risk of chemical alteration, which is a major cause of experimental failure.
Стилі APA, Harvard, Vancouver, ISO та ін.
12

Brown, Maxwell Christopher. "The Matuyama-Brunhes geomagnetic field reversal: a global and temporal perspective." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490805.

Повний текст джерела
Анотація:
Understanding the global and temporal evolution of the geomagnetic field during reversals can provide important constraints on conditions at the core-mantle boundary and on geodynamo processes. However, the behaviour of the geomagnetic field during reversals is unclear. Many palaeomagnetic· studies from both volcanic and sedimentary sequences have aimed to uncover details of the reversal processes; however, a paucity of data has made robust conclusions about reversal behaviour difficult. The model CALS7K.2 has been used to explore the possible influence of the timevarying non-dipole components of the geomagnetic field during field reversals. Results generated by the model suggest that non-dipole components could add significant structure to the field during the reversal processes. Globally, the main polarity reversal is variable in duration and rapid reversals on sub-decadal time-scales are seen for a small number of locations. The model generates variable reversal paths; however, there is a longitudina} preference for certain longitudinal paths, both spatial~y and, more weakly, temporally. Directional reversal features are not globally synchronous: some polarity changes finish before they start elsewhere; however, variations in intensity appear more coherent. The Matuyama-Brunhes reversal is the most recent geomagnetic field reversal ('''780 ka) and is recorded in numerous sedimentary and volcanic sequences. It provides our best chance to characterise a reversal globally. Volcanic sequences from La Palma and Guadeloupe that record the Matuyama-Brunhes boundary, possible precursors, and fluctuations in the magnetic field prior to the main polarity reversal, have been investigated. Absolute palaeointensity was determined using the microwave technique and palaeodirectional results were obtained from thermal demagnetisation. Ten flows from the twenty-nine flows studied gave reliable mean pafaeointensities; however, only one of the ten flows records a transitional direction. The VDM determined from this flow is 1.9 ± 0.6 (±IT) x 1022 Am2 . Analysis of all Matuyama-Brunhes data suggests that the main directional changes occurred once the VDM was reduced below 3 x 1022 Am2 ('''40% of the present field value). Further comparisons with palaeointensity data compiled from all reversals younger than 20 Ma supports this conclusion; however, the lack of transitional data does not allow us to make any truly robust statements about the transitional field behaviour.
Стилі APA, Harvard, Vancouver, ISO та ін.
13

Martin, J. E. "Spectral analysis of aeromagnetic data and investigation of errors in spherical harmonic models." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376255.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
14

Share, J. A. "An automated superconducting magnetometer for measuring samples at elevated temperatures." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380272.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
15

Maier, Thorsten. "Multiscale geomagnetic field modelling from satellite data theoretical aspects and numerical applications /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967076935.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
16

Mozzoni, David. "The changing geomagnetic field from the ionosphere to the core mantle boundary." Potsdam : GFZ [u.a.], 2008. http://bib.gfz-potsdam.de/pub/str0802/0802.pdf.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
17

Yamazaki, Ken'ichi. "Study on methods for regional geomagnetic field modeling to detect tectonomagnetic signals." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144196.

Повний текст джерела
Анотація:
Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第12113号
理博第3007号
新制||理||1448(附属図書館)
23949
UT51-2006-J108
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 大志万 直人, 教授 田中 良和, 教授 橋本 学
学位規則第4条第1項該当
Стилі APA, Harvard, Vancouver, ISO та ін.
18

Sydorenko, D., and I. Hretskyi. "Continuous cultivation system Photobacterium phosphoreum for biological monitoring of the geomagnetic field." Thesis, Київський національний університет технологій та дизайну, 2020. https://er.knutd.edu.ua/handle/123456789/15573.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
19

Molaei, Hamid. "Control of Induction Motor Drives in the Field Weakening Region Fed by a Boost Converter." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

Знайти повний текст джерела
Анотація:
Induction motors are usually fed by voltage source inverters. In some cases, it is necessary to increase the speed of the motor beyond the rated speed. This could be done by increasing the supply voltage (which is not always possible) or by field weakening. Field weakening algorithms are desirable since the current and the voltage of the motor cannot exceed the rated values. However, the range of the controlled speed is limited because of the limitation of the input voltage of the inverter. In this project, considering the limitation of current and voltage, the fundamentals of the field weakening in induction motor are reviewed. Th motor performance is evaluated under a variable range of the input DC voltage. A three-phase boost converter is used to regulate the input DC voltage of the inverter. In fact, when the requested voltage of the control algorithm is greater than the producible voltage of the inverter, the input DC voltage of the inverter is increased by the boost converter. The performance of this drive is evaluated in terms of current, torque and speed of induction motor. Besides, the efficiency of the drive is discussed.
Стилі APA, Harvard, Vancouver, ISO та ін.
20

Soong, Wen Liang. "Design and modelling of axially-laminated interior permanent magnet motor drives for field-weakening applications." Thesis, University of Glasgow, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320328.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
21

Frassl, Martin [Verfasser]. "From curse to blessing: harnessing geomagnetic field disturbances for ubiquitous navigation / Martin Frassl." Ulm : Universität Ulm, 2019. http://d-nb.info/1181190436/34.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
22

Boyd, M. "The intensity of the geomagnetic field recorded in Cambridge bricks since 1440 A.D." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377209.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
23

Kitaba, Ikuko, Masayuki Hyodo, Takeshi Nakagawa, Shigehiro Katoh, David L. Dettman, and Hiroshi Sato. "Geological support for the Umbrella Effect as a link between geomagnetic field and climate." NATURE PUBLISHING GROUP, 2017. http://hdl.handle.net/10150/622630.

Повний текст джерела
Анотація:
The weakening of the geomagnetic field causes an increase in galactic cosmic ray (GCR) flux. Some researchers argue that enhanced GCR flux might lead to a climatic cooling by increasing low cloud formation, which enhances albedo (umbrella effect). Recent studies have reported geological evidence for a link between weakened geomagnetic field and climatic cooling. However, more work is needed on the mechanism of this link, including whether the umbrella effect is playing a central role. In this research, we present new geological evidence that GCR flux change had a greater impact on continental climate than on oceanic climate. According to pollen data from Osaka Bay, Japan, the decrease in temperature of the Siberian air mass was greater than that of the Pacific air mass during geomagnetic reversals in marine isotope stages (MIS) 19 and 31. Consequently, the summer land-ocean temperature gradient was smaller, and the summer monsoon was weaker. Greater terrestrial cooling indicates that a reduction of insolation is playing a key role in the link between the weakening of the geomagnetic field and climatic cooling. The most likely candidate for the mechanism seems to be the increased albedo of the umbrella effect.
Стилі APA, Harvard, Vancouver, ISO та ін.
24

Obuchovski, Romuald. "Lietuvos teritorijos geomagnetinio lauko parametrų ir jų kitimo nustatymas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20061106_110627-76433.

Повний текст джерела
Анотація:
Determination of Earth geomagnetic field parameters and research of their variation is an actual and complex problem of natural science. It is related to knowledge of the state of natural physical system outer parameters of present geophysical and geodynamical processes. Variation of geomagnetic field is continuous process evident in different Earth surface places but in different ways. It can be determined by precise measurements. Precise repeated observations of geomagnetic field parameters at repeat stations is one of basic methods. For determination of certain epoch geomagnetic field parameters, detailed information on geomagnetic field and its variations is necessary. Data of geomagnetic field research is used for solution of different theoretical and practical tasks. Data is important for solving tasks of navigation, geophysics, geodynamics, explorations of minerals. According requirements of NATO and ICAO (International Civil Aviation Organization) – parameters of geomagnetic field are presented on the topographic maps and navigation charts of the air ports. Compass or director is used in geodesy for orientation, when instrument arrow is oriented along lines of geomagnetic field. Information on geomagnetic declination is necessary for direction determination in this case. Value of declination and its annual change is presented on topographical maps. Geomagnetic and gravimetric data are useful for exploration of minerals. Gravity value and geomagnetic induction help us... [to full text]
Стилі APA, Harvard, Vancouver, ISO та ін.
25

Magnussen, Freddy. "On design and analysis of synchronous permanent magnet machines for field-weakening operation in hybrid electric vehicles." Doctoral thesis, KTH, Electrical Systems, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-52.

Повний текст джерела
Анотація:

A regular vehicle of today is equipped with an internal combustion engine that runs on either gasoline or diesel, which are fossil fuels from oil reserves that are millions of years old. In all types of combustion processes carbon dioxide and several other emissions are produced. There are none known technologies of today that can reduce the emissions of carbon dioxide from combustion, but the amount that is produced is mainly dependent on the fuel that is used. Combustion of fossil fuels increases the contamination of carbon dioxide in the atmosphere and diminishes the oil resources. The results are global warming and empty oil reserves within a few decades with the current production tempo, in addition to many other pollution effects that are harmful to the environment. A transition towards a society based on sustainable transportation is therefore urgent. The hydrogen fuel cell powered car with an electric propulsion system has the potential to be the car of the future that possesses the required characteristics of no harmful tailpipe emissions. There are some obstacles in the way for an early commercialisation, including the expensive catalysts used today and the lack of an infrastructure based on hydrogen, though. The hybrid electric vehicle, with both a conventional as well as an electric drivetrain, is a natural candidate for making the transition from the conventional car towards the car of the future.

This thesis is focused on the design and analysis of permanent magnet machines for a novel hybrid electric vehicle drive system called the Four Quadrant Transducer. A number of electrical machine aspects are identified, including cores of soft magnetic composites, fractional pitch concentrated windings, core segmentation, novel machine topologies and cost effective production methods. The main objective is to analyse and judge the many unconventional machine aspects of which some may have the potential to improve the performance and reduce the cost of permanent magnet machines. Another objective is to study the effects of the use of fossil fuels and describe them with a new perspective and thereby make one small contribution to the debate about energy issues. Much focus has been spent on the theory of concentrated windings for permanent magnet machines. The potential parasitic effects and methods to improve the torque performance have been described. Other topics that have been given a high priority are material and power loss studies. An important contribution to the understanding of iron losses during field-weakening operation has been presented. A comprehensive use of finite element modeling has been done in the analysis combined with measurements on several laboratory prototypes.

The Four Quadrant Transducer drivetrain and its two electrical machines intended for a midsized passenger car has been studied. The gearbox can be of a simple single stage type, which reduces the mechanical complexity and makes the traction performance of the vehicle smooth, without gear changes and drops in power. Simulations on a complete hybrid system show that fuel savings of more than 40% compared to a conventional vehicle can be achieved at citytraffic driving. The savings are modest at highway driving, since the engine is required to operate at high power during such conditions, and the support from the electrical system is negligible. The laboratory prototypes have shown that it is possible to manufacture high performance electrical machines with high material utilization and potential for automated production. The described concepts offer cost effective solutions for future drive systems in automotive and industrial applications. A number of weaknesses with the presented constructions have also been characterized, which should serve as guidelines for creating more optimized machines.

Стилі APA, Harvard, Vancouver, ISO та ін.
26

Wardinski, Ingo. "Core surface flow models from decadal and subdecadal secular variation of the main geomagnetic field." Potsdam : Geoforschungszentrum, 2005. http://www.gfz-potsdam.de/bib/pub/str0507/0507.htm.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
27

Wardinski, Ingo. "Core surface flow models from decadal and subdecadal secular variation of the main geomagnetic field." [S.l.] : [s.n.], 2004. http://www.diss.fu-berlin.de/2005/70/index.html.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
28

Turton, Ian. "Temporal and spatial variations of the geomagnetic field, up to a timescale of 10⁵ years." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/11472.

Повний текст джерела
Анотація:
This thesis comprises two parts. The main part is involved with laboratory studies of the palaeosecular variation of the geomagnetic field as recorded in lake sediments. The natural remanent magnetization of the sediments cored from the two Italian maar lakes, Lago di Monticchio and Lago di Martignano, has been studied. Further studies were carried out on the sediments of Lago di Martignano to determine the cause of large variations in the magnetic intensity of the sediments with an age of ˜ 6000 years BP and it was concluded that this was caused by the arrival of Neolithic man and the advent of agriculture in the catchment area. The directional record for this lake was also compared to the established record for north west Europe. Several declination and inclination features could be correlated between the two records. The record from Lago di Martignano can be accepted as a regional palaeomagnetic reference curve for central Italy. Cores up to 50m long were taken from Lago di Monticchio. Whilst not yet firmly dated, it is agreed that this record spans the last 250,000 years. A relative palaeointensity record has been calculated and spectral analysis has been carried out. It is concluded provisionally that the palaeointensity recorded in the sediments was effected by the astronomical frequencies associated with precession of the earth, the eccentricity and the obliquity of the Earth's orbit. The second part of this thesis is concerned with modelling the palaeosecular variations as recorded in sediments around the world through the Holocene, i.e. the last 10,000 years. The properties of sequential secular variation records from sediments are compared with palaeosecular variation scatter determined from sets of lava flows. It is concluded that a comparison between PSV recorded in lava flows and lake sediments is valid.
Стилі APA, Harvard, Vancouver, ISO та ін.
29

Sherwood, G. J. "The Middle to Late Miocene geomagnetic field : Implications of new results from New Zealand lavas." Thesis, Bucks New University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374827.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
30

Nakano, Shinya. "Variations of large-scale field-aligned currents and their effects on mid-latitude geomagnetic disturbances." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147822.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
31

Patra, Swadesh. "The Contribution of Magnetospheric Currents to Ground Magnetic Perturbation during Geomagnetic Storms." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1719.

Повний текст джерела
Анотація:
A geomagnetic storm is triggered in response to a disturbance in the solar wind. The earth's ring current gets energized during a geomagnetic storm, which leads to a decrease in the horizontal component of the geomagnetic field on the earth's surface. The Disturbance Storm Time (Dst) index, which is a measure of the intensity of the ring current, is calculated by taking the average of this decrease in the horizontal intensity across four low latitude magnetometer stations and removing the quiet time secular variations. The rate of decrease of the Dst index is an indicator of the deenergization of the ring current particles. But there are several issues with the Dst measurement as a proxy of the ring current energy. In particular, the percentage contribution of the tail current effect to the Dst index is still debated. In this work, an effort has been made to separate and quantify the possible contribution of the tail current to the Dst index. The relative contribution for a selected set of storms for which the interplanetary magnetic field turned northward abruptly after the peak in Dst was observed is estimated. The WINDMI model of the nightside magnetosphere is used to investigate the contributions of ring current, magnetotail current, and magnetopause current on the observed two-phase decay of the Dst index. The role of different solar wind magnetosphere coupling functions on the Dst index calculated by the WINDMI model is also investigated. The performance of four other coupling functions in addition to the rectified vBs is evaluated. These coupling functions emphasize different physical mechanisms to explain the energy transfer into the magnetosphere due to solar wind velocity, dynamic pressure, magnetic field, and Mach number. One coupling function is due to Siscoe, another by Borovsky, and two by Newell. The results indicate that for a majority of cases, at most only vx, By, and Bz are needed to sufficiently account for the supply of energy to the ring current and geotail current components that contribute to the Dst index. The capabilities of the WINDMI model to reliably determine the state of the global magnetosphere are improved by employing the the Magnetotail (MT) index as a measurement constraint during large geomagnetic storms. The MT index is used as a proxy for the strength of the magnetotail current in the magnetosphere. The inclusion of the MT index as an optimization constraint in turn increases our confidence that the ring current contribution to the Dst index calculated by the WINDMI model is correct during large geomagnetic storms. To improve the models prediction of AL index, we also modify the ionospheric conductivity and fit to two substorms. The rate of reduction of convection in the magnetotail for some of these storms is numerically simulated by using inner magnetospheric models like the Fok Ring Current (FRC) and the Rice Convection Model along with the global BATSRUS model at the community coordinated modeling center. Model results are compared against magnetometer data by creating movie maps from several low-latitude magnetometer stations. The results indicate the contribution from the tail current to the Dst is important. In addition, the reduction of the cross-tail current during substorm dipolarization is predicted by the measured isotropic boundary locations. Several well known phenomena are identified in the magnetometer movie maps.
Стилі APA, Harvard, Vancouver, ISO та ін.
32

Liu, Jiabo [Verfasser], Norbert [Akademischer Betreuer] Nowaczyk, and Helge Wolfgang [Akademischer Betreuer] Arz. "Dynamics of the geomagnetic field during the last glacial / Jiabo Liu ; Norbert Nowaczyk, Helge Wolfgang Arz." Potsdam : Universität Potsdam, 2019. http://d-nb.info/1218404833/34.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
33

Michalareass, George. "Development, evaluation and application of a geomagnetic reference field model for attitude determination of small satellites." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420197.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
34

Liu, Jiabo Verfasser], Norbert [Akademischer Betreuer] Nowaczyk, and Helge Wolfgang [Akademischer Betreuer] [Arz. "Dynamics of the geomagnetic field during the last glacial / Jiabo Liu ; Norbert Nowaczyk, Helge Wolfgang Arz." Potsdam : Universität Potsdam, 2019. http://d-nb.info/1218404833/34.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
35

Mejia, Victoria. "Geomagnetic field for the past 5 myr recorded in lava flows from British Columbia, Patagonia, and Mexico." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010071.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
36

Gratton, Martin Nicholas. "Variation of geomagnetic field intensity over the last 45,000 years in Hawaii using the microwave palaeointensity technique." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402681.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
37

Hammond, Megan. "The use of archaeomagnetism to answer archaeological and geomagnetic questions with particular focus on determination of the strength of the geomagnetic field in the Middle East during the Bronze Age." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2014343/.

Повний текст джерела
Анотація:
The principles of archaeomagnetism can be applied to answer archaeological and geomagnetic questions and examples of both are presented in this thesis. Firstly, this thesis demonstrates the use of archaeomagnetism to establish the maximum palaeotemperature reached in a kiln at the Oylum Höyük archaeological site in Turkey. A maximum temperature of between 600 and 700 °C was determined confirming that the feature was more likely to have been a lime kiln than a bread oven. Archaeomagnetism was next used to determine the relative ages of different construction events on the St Jean Poutge archaeological site in Southern France. The results of archaeointensity experiments on 137 core samples taken from bricks and tiles confirmed the different relative ages of two construction events. Average intensity values determined using Thermal Thellier-Thellier methods were 56±7 and 58±8 for the 2nd Century AD and 68±6 and 68±7 for the 3rd Century AD. There is an increasing body of evidence that the geomagnetic field in the Middle East during the Bronze Age reached exceptionally high field values extremely quickly. Both archaeomagnetic jerks (marked by sharp cusps in geomagnetic field direction coinciding with intensity maxima) and geomagnetic spikes (where the field rises and falls over a period of less than 30 years with associated virtual axial dipole moment fluctuations of at least 70 ZAm2 /~38 µT) have been proposed to have occurred in the Middle East between 3000 BC and 0 BC. Here, Coe and IZZI method archaeointensity experiments were carried out on 154 Bronze Age pot sherds from two archaeological sites in Turkey, Tell Atchana and Kilise Tepe, and 2 archaeological sites in Cyprus, Marki Alonia and Bellapais Vounous. In addition, thermal Thellier experiments were conducted on 18 mud brick cores from Tell Atchana. The results of these experiments were corrected for cooling rate whilst experimental design mitigated the effects of anisotropy. A success rate of 56% was recorded overall. The effects of applying cooling rate corrections, anisotropy corrections and the impact of varying archaeointensity selection criteria cut-off values, on the results, are discussed in this thesis. An average field value of 47µT was determined for Turkey over the time period ~2200-~700 BC which is indistinguishable from the current average field value. An archaeointensity value of 84 µT (153 ZAm2) was measured for the time period 800-600 BC. This is consistent with data from other authors who found evidence of high geomagnetic field intensity in the Middle East around 1000 BC. It is proposed here that this geomagnetic intensity high was of a longer duration and felt over a wider geographic area than has previously been suggested. Contrary to previously published studies based in Syria, evidence is presented here of decreasing geomagnetic field intensity in Cyprus between 2400 BC and 1900 BC. The proposal that an archaeomagnetic jerk was experienced in Cyprus over this time period is therefore rejected.
Стилі APA, Harvard, Vancouver, ISO та ін.
38

Holá, Magda. "Interakce architektury a geomagnetického pole." Doctoral thesis, Vysoké učení technické v Brně. Fakulta architektury, 2013. http://www.nusl.cz/ntk/nusl-233248.

Повний текст джерела
Анотація:
With the application of new technological trends and principles of scientific research in general, places on environmental influences (everything what surrounds human - building interior and exterior materials, urban areas) and also with sustainable development and ecology, etc., and on health and psychological well-being humans and thus puts on architecture and building entirely new demands on the application of new principles. Due to global climate change, which recently published the official report of the International Panel on Climate Change (IPCC), are placed on reducing the emissions into the atmosphere greater demands on. If architects previously were requested by the client, building with optimal solutions and functional expression of aesthetic quality, so now in addition to increasing demand on building´s solution with low power consumption using environmentally friendly materials from renewable resources and completely satisfying idea of sustainable development. Global societal trends is reverting to the traditional approaches to creating an environment (the application of natural materials, Feng Shui, Building Biology, etc.). The growing trend in today's society on issues of sustainable development, conservation of natural conditions, examining the effects of construction on human health and psychological well-being, which the aims bring together experts seemingly unrelated fields such as geophysics, medicine, architecture, civil engineering, etc., and their findings, according to aspects of the disciplines draw general rules of healthy living. Emerging and still evolving field aims to examine the relationship between man and his environment. The logical starting point is therefore in the context of examining the structure of the first dwelling. Buildings where people spend at least one third of their life. Building, whose location, orientation, mass, materials used in building itself as well as those that surround people in the interior, and many others will affect the physical and physiological action. Not only health but also mental well-being of man is as much determined by a whole range of relationships and linkages. Structural system guidelines for healthy living is the main reason of the work, clear what assumptions we have taken into account in the design and how it specifically relates to a quality place to rest – the Geomagnetic field is one of the base point, which lead to healthy living. Interaction of architecture and geomagnetic field and their values are processed in the evaluation system. It would lead to clarification of the relationship between the occurrence of these anomalies and building materials, construction, site selection for construction of buildings and other solutions. I will desribing the relationship between human´s health and the incidence of these artificial or natural anomalies at the same time.
Стилі APA, Harvard, Vancouver, ISO та ін.
39

Chin, Yung-Kang. "A permanent magnet synchronous motor for an electric vehicle - design analysis." Licentiate thesis, KTH, Electrical Systems, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1763.

Повний текст джерела
Анотація:

This thesis presents the study and the design analysis of apermanent magnet synchronous motor (PMSM) for the tractionapplication of an electric vehicle. An existing inductiontraction motor for an electric forklift benchmarks the expectedperformances of the proposed PMSM design. Further, thepossibility of using the identical stator as the one used inthe induction motor is explored for the fast prototyping. Theprototype motor is expected to be field-weakened and to have aconstant power speed range (CPSR) of 2.5 to 3.

A design approach based on the CPSR contour plot in aninterior permanent magnet (IPM) parameter plane is derived toobtain the possible designs that meet all the designspecifications and the targeted CPSR. This study provides thepossible alternative designs for the subsequent futureprototype motors.

An analytical approach to estimate the iron loss in PMsynchronous machines is developed and included in the designprocedure. The proposed technique is based on predicting theflux density waveforms in the various regions of the machine.The model can be applied at any specified load condition,including the field-weakening operation region. This model canbe ultimately embedded in the design process for a routine usein loss estimations.

The first prototype motor with an inset permanent magnetrotor has been built and the available measurements are used tovalidate the design performance. In particular, the thermalanalyses based both on the lumped-circuit approach and thenumerical method are compared with the measured results. Asecond and possibly a third prototype motor targeting a widerand higher performance will be carried out in the continuingphase of the project.

Keywords:Constant Power Speed Range, Electric Vehicles,Field-weakening, Reference Flux Linkage, Iron Loss, PermanentMagnet Synchronous Motor, Thermal Analysis

Стилі APA, Harvard, Vancouver, ISO та ін.
40

Lohmann, Kenneth John. "Neural correlates of magnetic field detection and geomagnetic orientation by the marine mollusk Tritonia diomedea / by Kenneth John Lohmann." Thesis, Connect to this title online; UW restricted, 1988. http://hdl.handle.net/1773/5247.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
41

Suttie, Neil. "Geomagnetic field archaeointensities from Britain and the application of the microwave palaeointensity method to materials of differing dielectric properties." Thesis, University of Liverpool, 2010. http://livrepository.liverpool.ac.uk/2777/.

Повний текст джерела
Анотація:
The strength of the geomagnetic field is a subject of both scientific and public interest, with the decay over the past 160 years leading to speculation as to whether we are entering a geomagnetic reversal. Prior to 1840, there was no capability for direct measurements of geomagnetic field strength; to investigate the field strength at this time, palaeomagnetic and archaeomagnetic determinations must be made. Here we investigate the strength of the field in Britain over the past 1500 years as recorded by archaeological artefacts including ceramics, brick and burnt sandstone. Results are derived using both microwave and thermal demagnetisation. The theory of microwave demagnetisation is fully explained and equations governing the absorption of energy by an archaeomagnetic sample in a microwave cavity are derived. As a result, the possibility of demagnetising a palaeomagnetic sample using microwaves without significant heating is demonstrated for the first time. Geomagnetic field archaeointensities from seven British sites are reported. A meta-analysis of global archaeointensity and palaeointensity data from 1590 to 1990 reveals that significant bias has been introduced to field models through inconsistent error estimation. It is shown that the principle source of uncertainty in archaeointensity should be considered as systematic, rather than experimental and that data of arbitrarily high precision can only marginally increase our knowledge of the field. Correspondingly, it is argued that while large data sets are informative enough to constrain the evolution of the geomagnetic field, archaeointensity can only have a limited application as an archaeomagnetic dating tool. It is demonstrated that when the uncertainties are properly quantified, the global data implies that the recent decay of the dipole, evident in magnetic observatory data from 1840 until the present day, is part of a longer term trend, starting as early as 1600.
Стилі APA, Harvard, Vancouver, ISO та ін.
42

Craig, Patrick Shane. "Quantitative Analysis of the Polarity Reversal Pattern of the Earth's Magnetic Field and Self-Reversing Dynamo Models." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369586504.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
43

Saturnino, Diana. "Une méthode d’observatoires virtuels pour décrire les variations temporelles du champ géomagnétique et applications aux mesures de la mission Swarm." Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=181308db-f221-4fd6-84dc-ccfc2af8e6cd.

Повний текст джерела
Анотація:
A description of the temporal variations of the main geomagnetic field (i. E. , the secular variation, or SV) is crucial to the understanding of core dynamo generation. It is known with high accuracy at observatory locations, which are globally unevenly located, hampering the determination of a global pattern of these variations. Satellites have allowed global surveys of the field and its SV. Their data has been used by global spherical harmonic models using data selection criteria to reduce external contributions. SV small spatial scales may not be well described by these models, and can show significant errors compared to ground measurements. This study attempts to extract temporal variation time series from satellite measurements as it is done at observatory locations. We follow a Virtual Observatories (VO) approach, defining a global mesh of VOs at satellite altitude. We apply an Equivalent Source Dipole (ESD) technique. For each VO and a given time interval all measurements are reduced to a unique location, leading to time series similar to those available at the ground. Synthetic data is first used to validate the approach. We then apply our scheme to Swarm mission measurements. We locally compare the VO-ESD derived time series to ground observations and to satellite-based model predictions. The approach is able to describe field's time variations at local scales. The global mesh of VO time series is used to derive global spherical harmonic models. For a simple parametrization the model well describes the trend of the magnetic field both at satellite altitude and at the surface. Nevertheless more complex modelling can be made to properly profit of VO-ESD time series
La description des variations temporelles du champ géomagnétique (variation séculaire ou SV) est cruciale pour la compréhension de la dynamo. La SV est connue avec une grande précision dans les observatoires magnétiques, qui ont une répartition spatiale inégale. Les satellites donnent des observations globales du champ et de sa SV. Leurs données sont utilisées par les modèles globaux en harmoniques sphériques. Les petites échelles spatiales de la SV décrites par ces modèles peuvent montrer des erreurs par rapport aux mesures des observatoires. Dans cette étude je tente d'extraire des séries temporelles avec des mesures satellitaires comme dans les observatoires. L'approche des observatoires virtuels (VO) est suivie. Un maillage global de volumes à l'altitude du satellite est défini. Pour cela, la technique des Equivalent Source Dipoles (ESD) est appliquée. Pour chaque VO et intervalle de temps donné, toutes les mesures sont réduites à un endroit unique, menant à des séries temporelles similaires à celles disponibles dans les observatoires à la surface. L’approche est validée avec des donnes synthétiques et puis appliquée aux mesures de la mission Swarm. Les séries temporelles VO-ESD sont comparées à celles à la surface et aux prédictions par un modèle. L'approche décrit correctement les variations temporelles du champ à l'échelle locale. Un maillage global de VO est construit et utilisé pour obtenir des modèles globaux. Les modèles sont capables de décrire l'évolution du champ magnétique à la fois à l'altitude du satellite et à la surface. Toutefois des modélisations plus complexes pourront être faites pour profiter des séries temporelles VO-ESD
Стилі APA, Harvard, Vancouver, ISO та ін.
44

Wardinski, Ingo [Verfasser]. "Core surface flow models from decadal and subdecadal secular variation of the main geomagnetic field / Geoforschungszentrum Potsdam. Vorgelegt von Ingo Wardinski." Potsdam : Geoforschungszentrum, 2005. http://d-nb.info/974254991/34.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
45

Tulloch, Andrew Malcolm. "A study of recent secular variation of the geomagnetic field as recorded by lavas from Mount Vesuvius and the Canary Islands." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317294.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
46

Morrison, Graeme A. "Thermally driven hydromagnetic dynamos." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312706.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
47

Batt, Catherine M., I. Zananiri, and D. H. Tarling. "Archaeomagnetic Applications for the Rescue of Cultural Heritage." Elsevier, 2008. http://hdl.handle.net/10454/4645.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
48

Rosa, Domingos João Miguel. "Modes de variabilité géomagnétiques et de météo spatiale à partir des données satellites." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU007/document.

Повний текст джерела
Анотація:
Ce travail porte sur l’anomalie de l’Atlantique Sud (SAA anglais). Nous avons étudié cette anomalie du champ magnétique principal à partir de données satellitaires afin de mieux connaître les différentes sources de ses variations temporelles. Nous avons appliqué l’analyse en composantes principales (PCA) à des données de flux de particules, de bruit d’un lidar embarqué et à des séries temporelles d’observatoires magnétiques virtuels - séries construites à partir de mesures satellitaires du champ géomagnétique. Les données de flux de particules proviennent de trois satellites de la série POES de la NOAA (POES 10, 12 et 15) ainsi que du satellite Jason-2 du CNES et de la NASA. Nous utilisons aussi le bruit affectant le lidar CALIOP du mini-satellite CALIPSO (CNES/NASA) comme substitut au flux de particules chargées heurtant ce satellite. Pour l’information géomagnétique, deux jeux de données d’observatoires virtuels construits à partir d’enregistrements des satellites CHAMP et Swarm ont été utilisés. Ces deux ensembles différents de données apportent des éclairages complémentaires sur l’anomalie de l’Atlantique Sud. L’analyse en composantes principales des données de flux de particules a permis de distinguer différents modes de variabilité, dus au soleil d’une part et au champ magnétique principal d’autre part. Le cycle solaire de 11 ans affecte à la fois le flux total de particules énergétiques à l’aplomb de l’anomalie de l’Atlantique Sud et leur distribution dans les différentes ceintures de radiation internes. Le champ magnétique principal, qui provient du noyau liquide de la Terre, est responsable d’une lente dérive de l’anomalie de l’Atlantique Sud et par ricochet de la région où il y a un flux intense de particules énergétiques. Une fois déconvolué le rôle du champ magnétique principal, on distingue deux composantes que l’on peut associer sans ambiguïté au cycle solaire. Sur des temps plus longs, nous avons finalement pu mettre en évidence une tendance dans le flux total de particules dans la région de l’Atlantique Sud. Peu d’analyses globales des modes de variabilité du champ interne ont été entreprises. Notre étude vise aussi à combler ce manque. L’analyse en composantes principales permet d’extraire jusqu’à trois modes d’origine interne et un mode annuel combinant contributions interne et externe. Ce dernier mode a une géométrie principalement quadrupolaire et zonale. Le premier des modes purement internes explique l’essentiel de la variabilité du champ et correspond à la variation séculaire moyenne au cours de l’intervalle de temps étudié. Il s’interprète principalement comme la variation de la partie du champ géomagnétique représentée par un dipôle qui serait de plus en plus décalé par rapport au centre de la Terre en direction de l’Asie du Sud-Est et qui serait aussi incliné par rapport à l’axe de rotation. Ainsi, ce simple modèle nous a été utile à la fois pour rendre compte du flux de particule au dessus de l’anomalie de l’Atlantique Sud et pour interpréter la variation du champ géomagnétique à l’échelle globale
This work focus on the study of the South Atlantic Anomaly (SAA) of the main magnetic field from satellite data, aiming at identifying different sources of variability. This is done by first applying the Principal Component Analysis (PCA) method to particle flux and dark noise data and then to Virtual Observatories (VOs) time series constructed from satellite magnetic records. Particle flux data are provided by three POES NOAA satellites (10, 12 and 15) and the Jason-2 satellite. Dark noise data, which can be interpreted as a proxy to particle flux, are provided by the CALIOP lidar onboard the CALIPSO satellite. The magnetic field information is used in the form of time series for VOs, which were computed from both CHAMP and Swarm data as two separate datasets. The two different groups of data provide different views of the South Atlantic Anomaly. Applying PCA to particle flux data on the SAA produces interesting modes that can be related with specific physical processes involved with the anomaly. The main sources that drive these modes are the Earth’s magnetic field and the Sun. The Sun’s 11-year cycle is a well-known quasi-period of solar activity. This work shows how it clearly affects the evolution of the energetic particles trapped in the inner Van Allen belt, by modulating both their total number and their distribution among different L-shells. The way particles become trapped and move near-Earth is also dictated by the main magnetic field geometry and intensity and so a good understanding of its variation allows for a better description of the evolution of these particles. The main magnetic field, with origin in the Earth’s liquid core, is responsible for a slow drift of the anomaly, associated to the Westward drift of several features of the main field. Changing the frame of reference to that of the eccentric dipole, we were able to identify two separate modes associated with the variability of the solar activity. On longer time-scales, we also observed a linear trend in the spatial evolution of the particle flux. A global analysis of variability modes of the Earth’s magnetic field has not been often addressed. This study also contributes to fill this gap. By decomposing satellite records of the magnetic field into PCA modes, we retrieved modes of internal origin and modes with large external contributions, with no a-priori considerations. An annual signal has been identified and associated with mainly external sources. It exhibits an interesting geometry dominated by a zonal quadrupolar geometry. As for the internal source, three separate modes were obtained from the longest time series analysed. The first of these modes explains most of the variability of the field and represents the mean secular variation. It is closely modelled by an eccentric tilted dipole moving away from the Earth’s center and toward under East Asia. As this study shows, this simple model turns out to be a useful tool that can be used both on regional studies of the SAA and on global studies of the geomagnetic field
Стилі APA, Harvard, Vancouver, ISO та ін.
49

Garcia, Alexander S. "Geomagnetic field intensities from Tertiary and late Carboniferous igneous rocks of the British Isles and Australia using modified Thellier and microwave palaeointensity techniques." Thesis, Kingston University, 2006. http://eprints.kingston.ac.uk/20376/.

Повний текст джерела
Анотація:
Thermal Coe-modified-Thellier (CMT) and microwave (MW) palaeointensity (PI) investigations have been conducted on the Permo-Carboniferous Great Whin Sill (GWS) of northeast England, the Tertiary dyke swarm from the Isle of Skye and rocks from the Eastern Australia Cenozoic igneous province. These results provide important new palaeointensity data for the global palaeointensity (PINT) database in sparsely covered time windows. The GWS complex comprises at least three temporally distinct phases of intrusive activity. Fifty-six samples split between two of these phases, dated at ca. 269Ma and ca. 294Ma, have been investigated. Rock-magnetic investigations indicate pseudo-single- domain (PSD) grain assemblage of magnetite, with Curie temperatures between 550[sup]°C and 560[sup]°C in most samples. On comparison, data from CMT and MW investigations could not be distinguished in terms of quality or their respective mean PI value. Combined CMT and MW results yield Virtual Dipole Moments (VDM) of 1.2±O.1x10[sup]22 Am[sup]2 and 1.6± O.2x10[sup]22 Am[sup]2 for the younger and older phases respectively. These results, when coupled with previous estimates within the PINT database, support the view that the geomagnetic field intensity was dominantly lower during the Permo-Carboniferous Reverse Superchron in comparison with the present day value. The Tertiary dyke swarm of Skye comprises basaltic and doleritic intrusions. Thermomagnetic results suggest that the dominant magnetic mineral is magnetite or low-Ti titanomagnetite, with Curie temperatures between 490[sup]°C and 570[sup]°C. Hysteresis data suggest that samples comprise a PSD grain size assemblage. Many samples carry two anti-parallel remanence components, but the secondary low temperature (100- 300[sup]°C) is unstable. A mean 2.2± 0.91x 10[sup]22 Am[sup]2 VDM is calculated for the ChRM between 300-550[sup]°C, from forty-three samples. Several basaltic lavas and intrusions were sampled and investigated from the Australian Cenozoic igneous rocks. Rock magnetic analysis indicates Ti-enriched titanomagnetite (TM[sub]70- TM[sub]50) as the dominant magnetic phase in all samples with pseudo-single domain characteristics. The primary titanomagnetite carries a stable single component magnetization. Comparable MW and CMT data combine to produce three mean VDMs; 4.7± 0.7x 10[sup]22 Am[sup]2, 2.9± 1.4x 10[sup]22 Am[sup]2 and 3.1± 1.7x 10[sup]22 Am[sup]2 for volcanic rocks dated at c.48Ma, 46Ma and 22Ma respectively. The low mean PI from both the British and Australian igneous provinces is comparable with results from contemporaneous rocks, documented in the PINT database, suggesting the early Tertiary field was weaker than that of the present day. Results from each of the sampled igneous provinces demonstrates comparability between the microwave and thermal CMT palaeointensity techniques. However, while the microwave method significantly shortens experimental time, no significant enhancements in data quality or success rates were achieved on the rocks investigated.
Стилі APA, Harvard, Vancouver, ISO та ін.
50

Martineau, Ryan J. "Parameterized Least-Squares Attitude History Estimation and Magnetic Field Observations of the Auroral Spatial Structures Probe." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4482.

Повний текст джерела
Анотація:
Terrestrial auroras are visible-light events caused by charged particles trapped by the Earth's magnetic eld precipitating into the atmosphere along magnetic eld lines near the poles. Auroral events are very dynamic, changing rapidly in time and across large spatial scales. Better knowledge of the low of energy during an aurora will improve understanding of the heating processes in the atmosphere during geomagnetic and solar storms. The Auroral Spatial Structures Probe is a sounding rocket campaign to observe the middle-atmosphere plasma and electromagnetic environment during an auroral event with multipoint simultaneous measurements for fine temporal and spatial resolution. The auroral event in question occurred on January 28, 2015, with liftoff the rocket at 10:41:01 UTC. The goal of this thesis is to produce clear observations of the magnetic eld that may be used to model the current systems of the auroral event. To achieve this, the attitude of ASSP's 7 independent payloads must be estimated, and a new attitude determination method is attempted. The new solution uses nonlinear least-squares parameter estimation with a rigid-body dynamics simulation to determine attitude with an estimated accuracy of a few degrees. Observed magnetic eld perturbations found using the new attitude solution are presented, where structures of the perturbations are consistent with previous observations and electromagnetic theory.
Стилі APA, Harvard, Vancouver, ISO та ін.
Також вас можуть зацікавити добірки на тему "Weakening of the geomagnetic field" для інших типів джерел:
Статті в журналах Книги
Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!

До бібліографії