13,267 research outputs found
Oscillation of Nonlinear Neutral Delay Differential Equations
2000 Mathematics Subject Classification: 34K15, 34C10.In this paper, we study the oscillatory behavior of first order nonlinear neutral delay differential equation
(x(t) − q(t) x(t − σ(t))) ′ +f(t,x( t − τ(t))) = 0,
where σ, τ ∈ C([t0,∞),(0,∞)), q О C([t0,∞), [0,∞)) and f ∈ C([t0,∞) ×R,R). The obtained results extended and improve several of the well known previously results in the literature. Our results are illustrated with an example
Hadron Production in Neutrino-Nucleon Interactions at High Energies
The multi-particle production at high energy neutrino- nucleon collisions are
investigated through the analysis of the data of the experiment CERN-WA-025 at
neutrino energy less than 260GeV and the experiments FNAL-616 and FNAL-701 at
energy range 120-250 GeV. The general features of these experiments are used as
base to build a hypothetical model that views the reaction by a Feynman diagram
of two vertices. The first of which concerns the weak interaction between the
neutrino and the quark constituents of the nucleon. At the second vertex, a
strong color field is assumed to play the role of particle production, which
depend on the momentum transferred from the first vertex. The wave function of
the nucleon quarks are determined using the variation method and relevant
boundary conditions are applied to calculate the deep inelastic cross sections
of the virtual diagram.Comment: 6 pages PDF forma
Cosmological solutions of massive gravity on de Sitter
In the framework of the recently proposed models of massive gravity, defined
with respect to a de Sitter reference metric, we obtain new homogeneous and
isotropic solutions for arbitrary cosmological matter and arbitrary spatial
curvature. These solutions can be classified into three branches. In the first
two, the massive gravity terms behave like a cosmological constant. In the
third branch, the massive gravity effects can be described by a time evolving
effective fluid with rather remarkable features, including the property to
behave as a cosmological constant at late time.Comment: 6 pages, 1 figure; discussion extended, a few references added,
improved analysis in Section
Accuracy of Circulation Estimation Schemes Applied to Discretised Velocity Field Data
Numerical experiments are conducted on the velocity field of the Oseen vortex to determine the effect of random errors in the velocity field on the circulation estimate. The circulation is estimated by either a velocity integral or a vorticity integral over a particular region of integration. A novel method for the determination of this region is used. The accuracy of circulation estimation schemes is characterised in terms of the velocity sample spacing, the amount of random noise in the velocity field and the vorticity estimation scheme used. It is found that, in general, the velocity integral outperforms the vorticity integral in terms of reducing total error
Efficient broadband highly dispersive HfO<sub>2</sub>/SiO<sub>2</sub> multilayer mirror for pulse compression in near ultraviolet
Pulsar Prospects for the Cherenkov Telescope Array
In the last few years, the Fermi-LAT telescope has discovered over a 100
pulsars at energies above 100 MeV, increasing the number of known gamma-ray
pulsars by an order of magnitude. In parallel, imaging Cherenkov telescopes,
such as MAGIC and VERITAS, have detected for the first time VHE pulsed
gamma-rays from the Crab pulsar. Such detections have revealed that the Crab
VHE spectrum follows a power-law up to at least 400 GeV, challenging most
theoretical models, and opening wide possibilities of detecting more pulsars
from the ground with the future Cherenkov Telescope Array (CTA). In this
contribution, we study the capabilities of CTA for detecting Fermi pulsars. For
this, we extrapolate their spectra with "Crab-like" power-law tails in the VHE
range, as suggested by the latest MAGIC and VERITAS results.Comment: 4 pages, 3 figures. In Proceedings of the 2012 Heidelberg Symposium
on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184
Maximum Loadability Enhancement with a Hybrid Optimization Method
Nowadays, a power system is operating in a stressed condition due to the increase in demand in addition to constraint in building new power plants. The economics and environmental constraints to build new power plants and transmission lines have led the system to operate very close to its stability limits. Hence, more researches are required to study the important requirements to maintain stable voltage condition and hence develop new techniques in order to address the voltage stability problem. As an action, most Reactive Power Planning (RPP) objective is to minimize the cost of new reactive resources while satisfying the voltage stability constraints and labeled as Secured Reactive Power Planning (SCRPP). The new alternative optimization technique called Adaptive Tumbling Bacterial Foraging (ATBFO) was introduced to solve the RPP problems in the IEEE 57 bus system. The comparison common optimization Meta-Heuristic Evolutionary Programming and original Bacterial Foraging techniques were chosen to verify the performance using the proposed ATBFO method. As a result, the ATBFO method is confirmed as the best suitable solution in solving the identified RPP objective functions
Reactivity of [Re\u3csub\u3e2\u3c/sub\u3e(CO)\u3csub\u3e8\u3c/sub\u3e(MeCN)\u3csub\u3e2\u3c/sub\u3e] with Thiazoles: Hydrido Bridged Dirhenium Compounds Bearing Thiazoles in Different Coordination Modes
Reactions of the labile compound [Re2(CO)8(MeCN)2] with thiazole and 4-methylthiazole in refluxing benzene afforded the new compounds [Re2(CO)7{μ-2,3-η2-C3H(R)NS}{η1-NC3H2(4-R)S}(μ-H)] (1, R = H; 2, R = CH3), [Re2(CO)6{μ-2,3-η2-C3H(R)NS}{η1-NC3H2(4-R)S}2(μ-H)] (3, R = H; 4, R = CH3) and fac-[Re(CO)3(Cl){η1-NC3H2(4-R)S}2] (5, R = H; 6, R = CH3). Compounds 1 and 2 contain two rhenium atoms, one bridging thiazolide ligand, coordinated through the C(2) and N atoms and a η1-thiazole ligand coordinated through the nitrogen atom to the same Re as the thiazolide nitrogen. Compounds 3 and 4 contain a Re2(CO)6 group with one bridging thiazolide ligand coordinated through the C(2) and N atoms and two N-coordinated η1-thiazole ligands, each coordinated to one Re atom. A hydride ligand, formed by oxidative-addition of C(2)–H bond of the ligand, bridges Re–Re bond opposite the thiazolide ligand in compounds 1–4. Compound 5 contains a single rhenium atom with three carbonyl ligands, two N-coordinated η1-thiazole ligands and a terminal Cl ligand. Treatment of both 1 and 2 with 5 equiv. of thiazole and 4-methylthiazole in the presence of Me3NO in refluxing benzene afforded 3 and 4, respectively. Further activation of the coordinated η1-thiazole ligands in 1–4 is, however, unsuccessful and results only nonspecific decomposition. The single-crystal XRD structures of 1–5 are reported
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