The Hide, Skeldon, Acheson dynamo revisited

2006 ◽  
Vol 463 (2077) ◽  
pp. 113-130 ◽  
Author(s):  
Irene M Moroz
Keyword(s):  
Magnetic Field ◽  
Original Model ◽  
Unstable Periodic Orbits ◽  
Dynamo Action ◽  
Multiple Attractors ◽  
Extensive Analysis ◽  
Coexistence Of Multiple Attractors ◽  
Bifurcation Transition ◽  
First Time ◽  
Selection Of

Hide et al . (Hide, Skeldon & Acheson 1996 Proc. R. Soc. A 452 , 1369–1395) introduced a nonlinear system of three coupled ordinary differential equations to model a self-exciting Faraday disk homopolar dynamo. A very small selection of its possible behaviours was presented in that paper. Subsequent studies have extended the system to incorporate the effects of a nonlinear motor, an external battery and magnetic field, the coupling of two or more identical dynamos together, among other things. In this paper, we return to the original model with a view to perform a more extensive analysis of the Hide et al . dynamo. For the first time, we present bifurcation transition diagrams, so that the two examples of chaotic dynamo action (shown in figure 9 in that paper) can now be placed into context. We exhibit the coexistence of multiple attractors and also identify the lowest order unstable periodic orbits pertaining to some specific cases.

Solar Internal Rotation and Dynamo Waves: A Two-Dimensional Asymptotic Solution in the Convection Zone

2000 ◽  
Vol 179 ◽  
pp. 379-380
Author(s):  
Gaetano Belvedere ◽  
Kirill Kuzanyan ◽  
Dmitry Sokoloff
Keyword(s):  
Magnetic Field ◽  
Asymptotic Solution ◽  
Internal Rotation ◽  
Convection Zone ◽  
General Idea ◽  
Dynamo Model ◽  
Axially Symmetric ◽  
Dynamo Action ◽  
Regeneration Rate ◽  
Dynamo Waves

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan & Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.

Competition of Verb Aspects and Its Resolution as a Creative Act (Based on the Material of Aspects Variants in the Texts by F. M. Dostoevsky)

2020 ◽  
Vol 81 (2) ◽  
pp. 56-63
Author(s):  
S. A. Karpukhin
Keyword(s):  
Traditional Method ◽  
Contextual Analysis ◽  
Verb Aspect ◽  
Component Theory ◽  
Two Component ◽  
Artistic Interpretation ◽  
New Perspective ◽  
First Time ◽  
Selection Of ◽  
Aspectual Meaning

The article considers the competition of verbal aspects from a new perspective. Instead of employing the traditional method of demonstrating this phenomenon — an empirical replacement of the aspect of a verb in a phrase with the opposite — the author examines Dostoevsky’s choice between the variants found in different manuscripts of the same text. For the first time, based on a two-component theory of the semantic invariant of a verb type, the aspectual meaning of the selection of a verb aspect is revealed and, as a result of contextual analysis, an artistic interpretation of the selected type is proposed.

Peculiarities of the juvenile period of the native Chechen genotypes of willow leaf pear (Pyrus salicifolia Pall.)

2020 ◽  
Vol 62 ◽  
pp. 32-38
Author(s):  
E. A. Dolmatov ◽  
R. B. Borzayev ◽  
A. N. Shaipov
Keyword(s):  
Chestnut Soil ◽  
Crop Breeding ◽  
Juvenile Period ◽  
Period 2 ◽  
Russian Research Institute ◽  
The Common ◽  
One Year ◽  
First Time ◽  
Selection Of ◽  
Creative Cooperation

The results of the study of the duration of the juvenile period of indigenous Chechen willow leaf pear genotypes (Pyrus salicifolia Pall.) are given in connection with the acceleration of the breeding process and the use of selected forms in pear breeding for high precocity. The studies were carried out in 2016-2019 at OOO “Orchards of Chechnya” in accordance with the Agreement on creative cooperation with the Russian Research Institute of Fruit Crop Breeding. The work was carried out in accordance with generally accepted programs and methods. The objects of the study were one-year and two-year-old pear seedlings obtained from sowing seeds of selected dwarf and low-growing local Chechen forms of willow pear (P. salicifolia Pall.), laying fruit buds on annual growths and seedlings of Caucasian pear (P. caucasica Fed.), 20 500 pcs. of each specie. The aim of the research was to study the potential of precocity of willow pear seedlings and to reveal of selected forms with the greatest degree of this trait. Stratified seeds were sown in the sowing department of the OOO “Orchards of Chechnya” production nursery in April, 2017. The seedlings were grown according to the common technology in dryland conditions on the plot with chestnut soil. The first fl owering of plants was noted in the spring, 2019. As a result of the research, for the first time on a large number of the experimental material it was found that in the off spring of the indigenous Chechen willow leaf pear genotypes, the selection of a little more than 2% of seedlings with a very short juvenile period (2 years) was possible. They are of great interest in accelerating the breeding process and in the selection of new pear varieties with high precocity. 20 willow leaf pear genotypes were selected for the further use in breeding for high precocity and as sources of the trait of short juvenile period.

scholarly journals A Virtual Telescope for the Open University Science Foundation Course

1998 ◽  
Vol 162 ◽  
pp. 100-105
Author(s):  
Andrew J. Norton ◽  
Mark H. Jones
Keyword(s):  
Social Science ◽  
Open University ◽  
Distance Teaching ◽  
The Arts ◽  
Wide Range ◽  
University Science ◽  
First Time ◽  
Degree Level ◽  
Selection Of

The Open University is the UK's foremost distance teaching university. For over twenty five years we have been presenting courses to students spanning a wide range of degree level and vocational subjects. Since we have no pre-requisites for entry, a major component of our course profile is a selection of foundation courses comprising one each in the Arts, Social Science, Mathematics, Technology and Science faculties. The Science Faculty's foundation course is currently undergoing a substantial revision. The new course, entitled “S103: Discovering Science”, will be presented to students for the first time in 1998.

scholarly journals Chemical Constituents of the Marine Sponge Aaptos aaptos (Schmidt, 1864) and Their Cytotoxic Activity

2021 ◽  
Vol 16 (2) ◽  
pp. 1934578X2199334
Author(s):  
Do Thi Trang ◽  
Bui Huu Tai ◽  
Dan Thuy Hang ◽  
Pham Hai Yen ◽  
Phan Thi Thanh Huong ◽  
...  
Keyword(s):  
Cytotoxic Activity ◽  
Spectral Data ◽  
Absolute Configuration ◽  
Marine Sponge ◽  
Chemical Constituents ◽  
2D Nmr ◽  
Extensive Analysis ◽  
First Time ◽  
Tddft Method ◽  
Mcf 7

Seven compounds (1-7) were isolated from the marine sponge Aaptos aaptos living in the Vietnamese sea. Their structures were determined as 2 hours, 5 H,7 H,9 H-9 S-hydroxy-imidazo[1,5- α]pyridine-1,3-dione (1), 3-([9-methylhexadecyl]oxy)propane-1,2-diol 2, 2,3-dihydro-2,3-dioxoaaptamine (3), indol-3-aldehyde (4), methyl indole-3-carboxylate (5) 4-hydroxy-5-(indole-3-yl)−5-oxo-pentan-2-one (6), and thymidine (7) by extensive analysis of HR-ESI-MS, 1D, and 2D NMR spectral data, as well as by comparison of the spectral data with those reported in the literature. In addition, the absolute configuration of 1 was determined from the experimental ECD spectrum and comparison of this with the theoretical ECD calculations using the TDDFT method. Compounds 1 and 2 were isolated from nature for the first time. Compound 3 induced cytotoxic activity against SK-LU-1, MCF-7, HepG2, and SK-Mel-2 cell lines with IC50 values of 41.27 ± 2.63, 40.70 ± 2.65, 34.31 ± 3.43, and 36.63 ± 1.40 µM, respectively.

scholarly journals Combining QTL Mapping and Gene Expression Analysis to Elucidate the Genetic Control of ‘Crumbly’ Fruit in Red Raspberry (Rubus idaeus L.)

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 794
Author(s):  
Luca M. Scolari ◽  
Robert D. Hancock ◽  
Pete E. Hedley ◽  
Jenny Morris ◽  
Kay Smith ◽  
...  
Keyword(s):  
Genetic Control ◽  
Developmental Disorder ◽  
Molecular Mechanisms ◽  
Developmental Stages ◽  
Microarray Experiment ◽  
Rubus Idaeus ◽  
Red Raspberry ◽  
Genotype By Sequencing ◽  
First Time ◽  
Selection Of

‘Crumbly’ fruit is a developmental disorder in raspberry that results in malformed and unsaleable fruits. For the first time, we define two distinct crumbly phenotypes as part of this work. A consistent crumbly fruit phenotype affecting the majority of fruits every season, which we refer to as crumbly fruit disorder (CFD) and a second phenotype where symptoms vary across seasons as malformed fruit disorder (MFD). Here, segregation of crumbly fruit of the MFD phenotype was examined in a full-sib family and three QTL (Quantitative Trait Loci) were identified on a high density GbS (Genotype by Sequencing) linkage map. This included a new QTL and more accurate location of two previously identified QTLs. A microarray experiment using normal and crumbly fruit at three different developmental stages identified several genes that were differentially expressed between the crumbly and non-crumbly phenotypes within the three QTL. Analysis of gene function highlighted the importance of processes that compromise ovule fertilization as triggers of crumbly fruit. These candidate genes provided insights regarding the molecular mechanisms involved in the genetic control of crumbly fruit in red raspberry. This study will contribute to new breeding strategies and diagnostics through the selection of molecular markers associated with the crumbly trait.

scholarly journals The on-axis magnetic well and Mercier's criterion for arbitrary stellarator geometries

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
P. Kim ◽  
R. Jorge ◽  
W. Dorland
Keyword(s):  
Magnetic Field ◽  
Original Work ◽  
Three Dimensional ◽  
Radial Distance ◽  
Analytical Form ◽  
One Dimensional ◽  
Modern Notation ◽  
Magnetic Well ◽  
First Time ◽  
Dimensional Integral

A simplified analytical form of the on-axis magnetic well and Mercier's criterion for interchange instabilities for arbitrary three-dimensional magnetic field geometries is derived. For this purpose, a near-axis expansion based on a direct coordinate approach is used by expressing the toroidal magnetic flux in terms of powers of the radial distance to the magnetic axis. For the first time, the magnetic well and Mercier's criterion are then written as a one-dimensional integral with respect to the axis arclength. When compared with the original work of Mercier, the derivation here is presented using modern notation and in a more streamlined manner that highlights essential steps. Finally, these expressions are verified numerically using several quasisymmetric and non-quasisymmetric stellarator configurations including Wendelstein 7-X.

Turbulent dynamo action at low magnetic Reynolds number

1970 ◽  
Vol 41 (2) ◽  
pp. 435-452 ◽  
Author(s):  
H. K. Moffatt
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Magnetic Energy ◽  
Magnetic Reynolds Number ◽  
Dynamo Action ◽  
Ohmic Dissipation ◽  
Magnetic Energy Density ◽  
Magnetic Diffusivity

The effect of turbulence on a magnetic field whose length-scale L is initially large compared with the scale l of the turbulence is considered. There are no external sources for the field, and in the absence of turbulence it decays by ohmic dissipation. It is assumed that the magnetic Reynolds number Rm = u0l/λ (where u0 is the root-mean-square velocity and λ the magnetic diffusivity) is small. It is shown that to lowest order in the small quantities l/L and Rm, isotropic turbulence has no effect on the large-scale field; but that turbulence that lacks reflexional symmetry is capable of amplifying Fourier components of the field on length scales of order Rm−2l and greater. In the case of turbulence whose statistical properties are invariant under rotation of the axes of reference, but not under reflexions in a point, it is shown that the magnetic energy density of a magnetic field which is initially a homogeneous random function of position with a particularly simple spectrum ultimately increases as t−½exp (α2t/2λ3) where α(= O(u02l)) is a certain linear functional of the spectrum tensor of the turbulence. An analogous result is obtained for an initially localized field.

A novel chaotic circuit with coexistence of multiple attractors and state transition based on two memristors

2021 ◽  
Vol 152 ◽  
pp. 111363
Author(s):  
Xujiong Ma ◽  
Jun Mou ◽  
Li Xiong ◽  
Santo Banerjee ◽  
Yinghong Cao ◽  
...  
Keyword(s):  
State Transition ◽  
Chaotic Circuit ◽  
Multiple Attractors ◽  
Coexistence Of Multiple Attractors

Contact resistance, coupling and hysteresis loss measurements of ITER Poloidal Field joint in parallel applied magnetic field

2021 ◽  
Author(s):  
Jianfeng Huang ◽  
Y. Ilyin ◽  
W.A.J. Wessel ◽  
Ruben Lubkemann ◽  
Erik Krooshoop ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Contact Resistance ◽  
Applied Magnetic Field ◽  
Applied Field ◽  
Simulated Data ◽  
Hysteresis Loss ◽  
Ac Loss ◽  
Field Conditions ◽  
Ac Losses ◽  
First Time

Abstract The inter-strand contact resistance and AC losses were measured on an ITER PF Coil joint in a parallel applied AC magnetic field. In addition, the hysteresis loss was measured as a function of the angle with the applied magnetic field on a NbTi strand of the same type as in the joint with a Vibrating Sample Magnetometer (VSM). The AC loss measurements were performed at four applied field conditions for combinations of 0 or 1 T offset field and 0.2 or 0.4 T sinusoidal amplitude. The hysteresis loss of the joint was compared with the measured AC loss density of the NbTi strand for the same field conditions as the joint AC loss measurement but with varying the angle of the applied field. The subsequent cable twist angles affect the hysteresis loss since the critical current and penetration field depend on the angle of the applied field. It is found that 15.5° is an effective angle for the calculation of the hysteresis loss of joint when compared to the single strand measurement. The inter-strand contact resistance measurements cover all the typical strand combinations from the five cabling stages of the individual conductors, as well as the strand combinations across the two conductors to characterize the inter-strand including the copper sole resistivity. It’s the first time to measure the contact resistances and AC losses of the full-size ITER PF joint. By comparing the measured and simulated data in the JackPot-ACDC model, it’s also the first time to obtain the accurate inter-strand, inter-petal and strand to copper sole contact resistivities, which are the main input parameters for the further quantitative numerical analysis of the PF joints, in any current and magnetic field conditions.

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