8,584 research outputs found
Contact Lie algebras of vector fields on the plane
The paper is devoted to the complete classification of all real Lie algebras
of contact vector fields on the first jet space of one-dimensional submanifolds
in the plane. This completes Sophus Lie's classification of all possible Lie
algebras of contact symmetries for ordinary differential equations. As a main
tool we use the abstract theory of filtered and graded Lie algebras. We also
describe all differential and integral invariants of new Lie algebras found in
the paper and discuss the infinite-dimensional case.Comment: 20 pages. Published copy, also available at
http://www.maths.warwick.ac.uk/gt/GTVol3/paper1.abs.htm
Application of convolve-multiply-convolve SAW processor for satellite communications
There is a need for a satellite communications receiver than can perform simultaneous multi-channel processing of single channel per carrier (SCPC) signals originating from various small (mobile or fixed) earth stations. The number of ground users can be as many as 1000. Conventional techniques of simultaneously processing these signals is by employing as many RF-bandpass filters as the number of channels. Consequently, such an approach would result in a bulky receiver, which becomes impractical for satellite applications. A unique approach utilizing a realtime surface acoustic wave (SAW) chirp transform processor is presented. The application of a Convolve-Multiply-Convolve (CMC) chirp transform processor is described. The CMC processor transforms each input channel into a unique timeslot, while preserving its modulation content (in this case QPSK). Subsequently, each channel is individually demodulated without the need of input channel filters. Circuit complexity is significantly reduced, because the output frequency of the CMC processor is common for all input channel frequencies. The results of theoretical analysis and experimental results are in good agreement
Status of Lattice QCD
Significant progress has recently been achieved in the lattice gauge theory
calculations required for extracting the fundamental parameters of the standard
model from experiment. Recent lattice determinations of such quantities as the
kaon parameter, the mass of the quark, and the strong coupling constant
have produced results and uncertainties as good or better than the best
conventional determinations. Many other calculations crucial to extracting the
fundamental parameters of the standard model from experimental data are
undergoing very active development. I review the status of such applications of
lattice QCD to standard model phenomenology, and discuss the prospects for the
near future.Comment: 20 pages, 8 embedded figures, uuencoded, 2 missing figures. (Talk
presented at the Lepton-Photon Symposium, Cornell University, Aug. 10-15,
1993.
Strong convergence rates of probabilistic integrators for ordinary differential equations
Probabilistic integration of a continuous dynamical system is a way of
systematically introducing model error, at scales no larger than errors
introduced by standard numerical discretisation, in order to enable thorough
exploration of possible responses of the system to inputs. It is thus a
potentially useful approach in a number of applications such as forward
uncertainty quantification, inverse problems, and data assimilation. We extend
the convergence analysis of probabilistic integrators for deterministic
ordinary differential equations, as proposed by Conrad et al.\ (\textit{Stat.\
Comput.}, 2017), to establish mean-square convergence in the uniform norm on
discrete- or continuous-time solutions under relaxed regularity assumptions on
the driving vector fields and their induced flows. Specifically, we show that
randomised high-order integrators for globally Lipschitz flows and randomised
Euler integrators for dissipative vector fields with polynomially-bounded local
Lipschitz constants all have the same mean-square convergence rate as their
deterministic counterparts, provided that the variance of the integration noise
is not of higher order than the corresponding deterministic integrator. These
and similar results are proven for probabilistic integrators where the random
perturbations may be state-dependent, non-Gaussian, or non-centred random
variables.Comment: 25 page
Charm elliptic flow at RHIC
Charm elliptic flow in heavy ion collisions at the Relativistic Heavy Ion
Collider (RHIC) is studied in a multiphase transport model. Assuming that the
cross section for charm quark scattering with other light quarks is the same as
that between light quarks, we find that both charm and light quark elliptic
flows are sensitive to the value of the cross section. Compared to that of
light quarks, the elliptic flow of charm quarks is smaller at low transverse
momentum but approaches comparable values at high transverse momentum. Similar
features are seen in the elliptic flow of charmed mesons as well as that of the
electrons from their semileptonic decays when the charmed mesons are produced
from quark coalescence during hadronization of the partonic matter. To describe
the large electron elliptic flow observed in available experimental data
requires a charm quark scattering cross section that is much larger than that
given by the perturbative QCD
Invariants of differential equations defined by vector fields
We determine the most general group of equivalence transformations for a
family of differential equations defined by an arbitrary vector field on a
manifold. We also find all invariants and differential invariants for this
group up to the second order. A result on the characterization of classes of
these equations by the invariant functions is also given.Comment: 13 page
Partonic effects on higher-order anisotropic flows in relativistic heavy-ion collisions
Higher-order anisotropic flows and in heavy ion collisions at
the Relativistic Heavy Ion Collider are studied in a multiphase transport model
that has previously been used successfully for describing the elliptic flow
in these collisions. We find that the same parton scattering cross
section of about 10 \textrm{mb} used in explaining the measured can also
reproduce the recent data on and from Au + Au collisions at
\textrm{AGeV}. It is further found that the is a more
sensitive probe of the initial partonic dynamics in these collisions than
. Moreover, higher-order parton anisotropic flows are nonnegligible and
satisfy the scaling relation , which
leads naturally to the observed similar scaling relation among hadron
anisotropic flows when the coalescence model is used to describe hadron
production from the partonic matter.Comment: 5 pages, 3 figures, version to appear in PRC as a Rapid Communicatio
Analisis Strategi Diferensiasi (Kasus Produk Telkom Speedy di Plasa Telkom Pekanbaru)
This research took place in The Plasa Telkom Pekanbaru. This research based on the amount of market opportunities to telecommunications services (internet) in Riau. These conditions provide an opportunity and also threat to telecommunications service provider (internet) business that targeting the same market, that effected competition conditions being increased intensely. These condition forced The Plasa Telkom Pekanbaru to designing and implementing an appropriate and efficient differentiation strategy to attract and retain customers. This study aims to analyze the differentiation strategy implemented of The Plasa Telkom Pekanbaru and constraints experienced in the face of telecommunications services in Riau.The Author used descriptive quantitative analysis method, Used questionnaire and interview to collecting data, and used accidental sampling as sample. Source of data was used primary data or obtained directly from the object of research data, and secondary data is data which Author collected from The Plasa Telkom Pekanbaru.The results of this research indicate that the differentiation strategy that has been implemented by The Plasa Telkom Pekanbaru is appropriate, but the strategy style of Speedys product must be considered and improved.Keywords: Differentiation strategy, telecommunication services, Telkoms product
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