794 research outputs found
Global action-angle coordinates for completely integrable systems with noncompact invariant submanifolds
The obstruction to the existence of global action-angle coordinates of
Abelian and noncommutative (non-Abelian) completely integrable systems with
compact invariant submanifolds has been studied. We extend this analysis to the
case of noncompact invariant submanifolds.Comment: 13 pages, to be published in J. Math. Phys. (2007
Accidents preventive practice for high-rise construction
The demand of high-rise projects continues to grow due to the reducing of usable land area in Klang Valley, Malaysia.The rapidly development of high-rise projects has leaded to the rise of fatalities and accidents.An accident that happened in a construction site can cause serious physical injury.The accidents such as people falling from height and struck by falling object were the most frequent accidents happened in Malaysian construction industry.The continuous growth of high-rise buildings indicates that there is a need of an effective safety and health management. Hence, this research aims to identify the causes of accidents and the ways to prevent accidents that occur at high-rise building construction site.Qualitative method was employed in this research. Interview surveying with safety officers who are involved in highrise building project in Kuala Lumpur were conducted in this research. Accidents were caused by man-made factors, environment factors or machinery factors.The accidents prevention methods were provide sufficient Personal Protective Equipment (PPE), have a good housekeeping, execute safety inspection, provide safety training and execute accidents investigation.In the meanwhile, interviewees have suggested the new prevention methods that were develop a proper site layout planning and de-merit and merit system among subcontractors, suppliers and even employees regarding safety at workplace matters.This research helps in explaining the causes of accidents and identifying area where prevention action should be implemented, so that workers and top management will increase awareness in preventing site accidents
Simulation of Flow of Mixtures Through Anisotropic Porous Media using a Lattice Boltzmann Model
We propose a description for transient penetration simulations of miscible
and immiscible fluid mixtures into anisotropic porous media, using the lattice
Boltzmann (LB) method. Our model incorporates hydrodynamic flow, diffusion,
surface tension, and the possibility for global and local viscosity variations
to consider various types of hardening fluids. The miscible mixture consists of
two fluids, one governed by the hydrodynamic equations and one by diffusion
equations. We validate our model on standard problems like Poiseuille flow, the
collision of a drop with an impermeable, hydrophobic interface and the
deformation of the fluid due to surface tension forces. To demonstrate the
applicability to complex geometries, we simulate the invasion process of
mixtures into wood spruce samples.Comment: Submitted to EPJ
Gaussian density estimates for the solution of singular stochastic Riccati equations
summary:Stochastic Riccati equation is a backward stochastic differential equation with singular generator which arises naturally in the study of stochastic linear-quadratic optimal control problems. In this paper, we obtain Gaussian density estimates for the solutions to this equation
Equidistribution of zeros of holomorphic sections in the non compact setting
We consider N-tensor powers of a positive Hermitian line bundle L over a
non-compact complex manifold X. In the compact case, B. Shiffman and S.
Zelditch proved that the zeros of random sections become asymptotically
uniformly distributed with respect to the natural measure coming from the
curvature of L, as N tends to infinity. Under certain boundedness assumptions
on the curvature of the canonical line bundle of X and on the Chern form of L
we prove a non-compact version of this result. We give various applications,
including the limiting distribution of zeros of cusp forms with respect to the
principal congruence subgroups of SL2(Z) and to the hyperbolic measure, the
higher dimensional case of arithmetic quotients and the case of orthogonal
polynomials with weights at infinity. We also give estimates for the speed of
convergence of the currents of integration on the zero-divisors.Comment: 25 pages; v.2 is a final update to agree with the published pape
Electronic and Magnetic Properties of Partially-Open Carbon Nanotubes
On the basis of the spin-polarized density functional theory calculations, we
demonstrate that partially-open carbon nanotubes (CNTs) observed in recent
experiments have rich electronic and magnetic properties which depend on the
degree of the opening. A partially-open armchair CNT is converted from a metal
to a semiconductor, and then to a spin-polarized semiconductor by increasing
the length of the opening on the wall. Spin-polarized states become
increasingly more stable than nonmagnetic states as the length of the opening
is further increased. In addition, external electric fields or chemical
modifications are usable to control the electronic and magnetic properties of
the system. We show that half-metallicity may be achieved and the spin current
may be controlled by external electric fields or by asymmetric
functionalization of the edges of the opening. Our findings suggest that
partially-open CNTs may offer unique opportunities for the future development
of nanoscale electronics and spintronics.Comment: 6 figures, to appear in J. Am. Chem. So
Eliashberg-type equations for correlated superconductors
The derivation of the Eliashberg -- type equations for a superconductor with
strong correlations and electron--phonon interaction has been presented. The
proper account of short range Coulomb interactions results in a strongly
anisotropic equations. Possible symmetries of the order parameter include s, p
and d wave. We found the carrier concentration dependence of the coupling
constants corresponding to these symmetries. At low hole doping the d-wave
component is the largest one.Comment: RevTeX, 18 pages, 5 ps figures added at the end of source file, to be
published in Phys.Rev. B, contact: [email protected]
Microstructure and Mechanical Properties of the in situ Β-Si 3 N 4 /Α′-SiAlON Composite
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65911/1/j.1151-2916.1994.tb04604.x.pd
Stochastic averaging using elliptic functions to study nonlinear stochastic systems
In this paper, a new scheme of stochastic averaging using elliptic functions is presented that approximates nonlinear dynamical systems with strong cubic nonlinearities in the presence of noise by a set of Itô differential equations. This is an extension of some recent results presented in deterministic dynamical systems. The second order nonlinear differential equation that is examined in this work can be expressed as % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWexLMBb50ujb% qeguuDJXwAKbacfiGaf8hEaGNbamaacqGHRaWkcaWGJbadcaaIXaGc% cqWF4baEcqGHRaWkcaWGJbadcaaIZaGccqWF4baEdaahaaWcbeqaai% aaiodaaaGccqGHRaWkcqaH1oqzcaWGMbGaaiikaiab-Hha4jaacYca% cqWFGaaicuWF4baEgaGaaiaacMcacqGHRaWkcqaH1oqzdaahaaWcbe% qaaiaaigdacaGGVaGaaGOmaaaaruWrL9MCNLwyaGGbcOGaa43zaiaa% cIcacqWF4baEcaGGSaGae8hiaaIaf8hEaGNbaiaacaGGSaGae8hiaa% IaeqOVdGNaaeikaiaadshacaqGPaGaaiykaiabg2da9iaaicdaaaa!645D![ddot x + c1x + c3x^3 + varepsilon f(x, dot x) + varepsilon ^{1/2} g(x, dot x, xi {text{(}}t{text{)}}) = 0] where c 1 and c 3 are given constants, ξ( t ) is stationary stochastic process with zero mean and ε≪1 is a small parameter. This method involves the laborious manipulation of Jacobian elliptic functions such as cn, dn and sn rather than the usual trigonometric functions. The use of a symbolic language such as Mathematica reduces the computational effort and allows us to express the results in a convenient form. The resulting equations are Markov approximations of amplitude and phase involving integrals of elliptic functions. Finally, this method was applied to study some standard second order systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43328/1/11071_2004_Article_BF00120672.pd
- …