8,129 research outputs found
Fomenko-Mischenko Theory, Hessenberg Varieties, and Polarizations
The symmetric algebra g (denoted S(\g)) over a Lie algebra \g (frak g) has
the structure of a Poisson algebra. Assume \g is complex semi-simple. Then
results of Fomenko- Mischenko (translation of invariants) and A.Tarasev
construct a polynomial subalgebra \cal H = \bf C[q_1,...,q_b] of S(\g) which is
maximally Poisson commutative. Here b is the dimension of a Borel subalgebra of
\g. Let G be the adjoint group of \g and let \ell = rank \g. Identify \g with
its dual so that any G-orbit O in \g has the structure (KKS) of a symplectic
manifold and S(\g) can be identified with the affine algebra of \g. An element
x \in \g is strongly regular if \{(dq_i)_x\}, i=1,...,b, are linearly
independent. Then the set \g^{sreg} of all strongly regular elements is Zariski
open and dense in \g, and also \g^{sreg \subset \g^{reg} where \g^{reg} is the
set of all regular elements in \g. A Hessenberg variety is the b-dimensional
affine plane in \g, obtained by translating a Borel subalgebra by a suitable
principal nilpotent element. This variety was introduced in [K2]. Defining Hess
to be a particular Hessenberg variety, Tarasev has shown that Hess \subset
\g^sreg. Let R be the set of all regular G-orbits in \g. Thus if O \in R, then
O is a symplectic manifold of dim 2n where n= b-\ell. For any O\in R let
O^{sreg} = \g^{sreg}\cap O. We show that O^{sreg} is Zariski open and dense in
O so that O^{sreg} is again a symplectic manifold of dim 2n. For any O \in R
let Hess (O) = Hess \cap O. We prove that Hess(O) is a Lagrangian submanifold
of O^{sreg} and Hess =\sqcup_{O \in R} Hess(O). The main result here shows that
there exists, simultaneously over all O \in R, an explicit polarization (i.e.,
a "fibration" by Lagrangian submanifolds) of O^{sreg} which makes O^{sreg}
simulate, in some sense, the cotangent bundle of Hess(O).Comment: 36 pages, plain te
On the feasibility of iron or chromium substitution for aluminium in the Al13-Keggin ion
Al-27 NMR measurements in the liquid and the solid state supplemented with chemical analysis of the mixed salts; unambiguously reveal that neither tetrahedral nor octahedral aluminium can be substituted by either iron or chromium in Al-13-Keggin ion salts prepared by conventional methods
Movement patterns and athletic performance of leopards in the Okavango Delta
Although leopards are the most widespread of all the big cats and are known for their adaptability, they are elusive and little is known in detail about their movement and hunting energetics. We used high-resolution GPS/IMU (inertial measurement unit) collars to record position, activity and the first high-speed movement data on four male leopards in the Okavango Delta, an area with high habitat diversity and habitat fragmentation. Leopards in this study were generally active and conducted more runs during the night, with peaks in activity and number of runs in the morning and evening twilight. Runs were generally short (less than 100 m) and relatively slow (maximum speed 5.3 m sβ1, mean of individual medians) compared to other large predators. Average daily travel distance was 11 km and maximum daily travel distance was 29 km. No direct correlation was found between average daily temperature and travel distance or between season and travel distance. Total daily energy requirements based on locomotor cost and basal metabolic rate varied little between individuals and over time. This study provides novel insights into movement patterns and athletic performance of leopards through quantitative high-resolution measurement of the locomotor, energetic, spatial and temporal movement characteristics. The results are unbiased by methodological and observational limitations characteristic of previous studies and demonstrate the utility of applying new technologies to field studies of elusive nocturnal species
Capturing the "Whole Tale" of Computational Research: Reproducibility in Computing Environments
We present an overview of the recently funded "Merging Science and
Cyberinfrastructure Pathways: The Whole Tale" project (NSF award #1541450). Our
approach has two nested goals: 1) deliver an environment that enables
researchers to create a complete narrative of the research process including
exposure of the data-to-publication lifecycle, and 2) systematically and
persistently link research publications to their associated digital scholarly
objects such as the data, code, and workflows. To enable this, Whole Tale will
create an environment where researchers can collaborate on data, workspaces,
and workflows and then publish them for future adoption or modification.
Published data and applications will be consumed either directly by users using
the Whole Tale environment or can be integrated into existing or future domain
Science Gateways
Ideal MHD theory of low-frequency Alfven waves in the H-1 Heliac
A part analytical, part numerical ideal MHD analysis of low-frequency Alfven
wave physics in the H-1 stellarator is given. The three-dimensional,
compressible ideal spectrum for H-1 is presented and it is found that despite
the low beta (approx. 10^-4) of H-1 plasmas, significant Alfven-acoustic
interactions occur at low frequencies. Several quasi-discrete modes are found
with the three-dimensional linearised ideal MHD eigenmode solver CAS3D,
including beta-induced Alfven eigenmode (BAE)- type modes in beta-induced gaps.
The strongly shaped, low-aspect ratio magnetic geometry of H-1 causes CAS3D
convergence difficulties requiring the inclusion of many Fourier harmonics for
the parallel component of the fluid displacement eigenvector even for shear
wave motions. The highest beta-induced gap reproduces large parts of the
observed configurational frequency dependencies in the presence of hollow
temperature profiles
ΠΠΎΠ΄Π΅ΡΠ½ΠΈΠ·Π°ΡΠΈΡ ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π½ΡΡ Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ² ΡΠ°Π·Π»ΠΈΡΠ½ΠΎΠΉ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠΈΡΠ»Π΅Π½Π½ΠΎΠ³ΠΎ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ
ΠΡΠΏΡΡΠΊΠ½Π°Ρ ΠΊΠ²Π°Π»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠ°Π±ΠΎΡΠ° 104 Ρ., 49 ΡΠΈΡ., 10 ΡΠ°Π±Π»., 20 ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΎΠ², 3 ΠΏΡΠΈΠ».
ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ»ΠΎΠ²Π°: ΠΌΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅, ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π½ΠΈΠΊ, ΡΠΎΠΏΠ»ΠΈΠ²Π½ΡΠΉ Π³Π°Π·, ΠΈΠ½ΡΠ΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΡ ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π°, ΠΏΡΠΈΠ½ΡΠ΄ΠΈΡΠ΅Π»ΡΠ½Π°Ρ ΠΊΠΎΠ½Π²Π΅ΠΊΡΠΈΡ, ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΡ, ΡΠ°ΡΡΠ΅ΡΠ½Π°Ρ ΡΠ΅ΡΠΊΠ°, ΠΏΡΠΈΡΠΎΠ΅Π΄ΠΈΠ½ΠΈΡΠ΅Π»ΡΠ½ΡΠΉ Π²ΠΈΡ
ΡΡ, ΡΠ΅ΠΏΠ»ΠΎΠ²ΠΎΠΉ ΠΏΠΎΡΠΎΠΊ, Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΌΠΎΠ΄Π΅Π»Ρ.
ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π½ΡΠΉ Π°ΠΏΠΏΠ°ΡΠ°Ρ, ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΠΉ Π΄Π»Ρ Π½Π°Π³ΡΠ΅Π²Π° ΡΠΎΠΏΠ»ΠΈΠ²Π½ΠΎΠ³ΠΎ Π³Π°Π·Π° ΠΏΠ΅ΡΠ΅Π΄ ΠΏΠΎΠ΄Π°ΡΠ΅ΠΉ Π΅Π³ΠΎ Π½Π° Π³ΠΎΡΠ΅Π»ΠΎΡΠ½ΡΠ΅ ΡΡΡΡΠΎΠΉΡΡΠ²Π°.
Π¦Π΅Π»Ρ ΡΠ°Π±ΠΎΡΡ - ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈΠ½ΡΠ΅Π½ΡΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π° ΠΏΡΠΈ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΠΌ ΡΠ΅ΡΠ΅Π½ΠΈΠΈ ΡΠ΅ΠΏΠ»ΠΎΠ½ΠΎΡΠΈΡΠ΅Π»Ρ Π² ΠΏΡΡΠΌΡΡ
ΠΊΡΡΠ³Π»ΡΡ
ΡΡΡΠ±Π°Ρ
Ρ ΠΈΡΠ΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΠ°ΠΌΠΈ ΡΠ΅ΠΏΠ»ΠΎΠΎΠ±ΠΌΠ΅Π½Π° ΠΈ Π°Π½Π°Π»ΠΈΠ· ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΡΡΡΠ±ΡΠ»ΠΈΠ·Π°ΡΠΎΡΠΎΠ².Final qualifying work 104 p., 49 fig., 10 tab., 20 sources, 3 application.
Keywords: mathematical modeling, heat exchanger, fuel gas, to vary the heat transfer, forced convection, turbulence, computational grid, connecting a whirlwind, heat flow, the geometric model.
The object of research is the heat exchanger that is used to heat the fuel gas before it is fed to the burners.
Objective - research intensified heat exchange in turbulent flow of coolant in straight circular pipes with itensifikatorami heat exchange and analysis of the effectiveness of different turbulence.
The study was carried out mathematical modeling of the object of study with the use of ANSYS package applications, analysis of the results and evaluation of the effectiveness of different types of turbulence
Syringomyelia: A review of the biomechanics
Syringomyelia is a neurological disorder caused by the development of one or more macroscopic fluid-filled cavities in the spinal cord. While the aetiology remains uncertain, hydrodynamics appear to play a role. This has led to the involvement of engineers, who have modelled the system in silico and on the bench. In the process, hypotheses from the neurosurgical literature have been tested, and others generated, while aspects of the system mechanics have been clarified. The spinal cord is surrounded by cerebrospinal fluid (CSF) which is subject both to the periodic excitation of CSF expelled from the head with each heartbeat, and to intermittent larger transients from cough, sneeze, etc., via vertebral veins. The resulting pulsatile flow and pressure wave propagation, and their possible effects on cord cavities and cord stresses, have been elucidated. These engineering contributions are here reviewed for the first time
Virtual Structure Constants as Intersection Numbers of Moduli Space of Polynomial Maps with Two Marked Points
In this paper, we derive the virtual structure constants used in mirror
computation of degree k hypersurface in CP^{N-1}, by using localization
computation applied to moduli space of polynomial maps from CP^{1} to CP^{N-1}
with two marked points. We also apply this technique to non-nef local geometry
O(1)+O(-3)->CP^{1} and realize mirror computation without using Birkhoff
factorization.Comment: 10 pages, latex, a minor change in Section 4, English is refined,
Some typing errors in Section 3 are correcte
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