1,870 research outputs found
Анализ эффективности осаждения влаги в выносных сепараторах АЭС
Объектом исследования является внешняя сепарация пара на АЭС
Цель работы – провести анализ эффективности осаждения влаги во внешних сепараторах АЭС. Определить влияние конструктивных факторов на процесс осаждения влаги и течения пара. На основе полученных результатов сравнить различные конструкции сепараторов, описать их преимущества и недостатки.
В процессе исследования проводились математическое и компьютерное моделирования течения влажного пара с помощью ПК FlowVision и программирования в среде Visual Basic.
В результате исследования были получены зависимости эффективности осаждения влаги и значения гидравлического сопротивления от характерных геометрических размеров жалюзийных сепараторов.
Экономическая эффективность/значимость работы заключается в исследовании возможностей повышеThe object of this study is the external separation at the nuclear power plant.
The purpose of the study is to analyze the efficiency of precipitation of moisture in the external separator; to determine the relation of structural factors to the process of catching of moisture and vapor flow; use these data to compare different designs of separators, describe their advantages and disadvantages.
The study carried out using mathematical and computer modeling of wet steam flow with a SP FlowVision and programming in Visual Basic environment.
The results of the study are relations of the efficiency of precipitation and hydraulic resistance to the characteristic geometric factors of corrugated plates separators.
Cost-effectiveness / value of the work concludes in the possibilities of improv
On approximate solutions of semilinear evolution equations
A general framework is presented to discuss the approximate solutions of an
evolution equation in a Banach space, with a linear part generating a semigroup
and a sufficiently smooth nonlinear part. A theorem is presented, allowing to
infer from an approximate solution the existence of an exact solution.
According to this theorem, the interval of existence of the exact solution and
the distance of the latter from the approximate solution can be evaluated
solving a one-dimensional "control" integral equation, where the unknown gives
a bound on the previous distance as a function of time. For example, the
control equation can be applied to the approximation methods based on the
reduction of the evolution equation to finite-dimensional manifolds: among
them, the Galerkin method is discussed in detail. To illustrate this framework,
the nonlinear heat equation is considered. In this case the control equation is
used to evaluate the error of the Galerkin approximation; depending on the
initial datum, this approach either grants global existence of the solution or
gives fairly accurate bounds on the blow up time.Comment: 33 pages, 10 figures. To appear in Rev. Math. Phys. (Shortened
version; the proof of Prop. 3.4. has been simplified
Adaptive FE-BE Coupling for Strongly Nonlinear Transmission Problems with Coulomb Friction
We analyze an adaptive finite element/boundary element procedure for scalar
elastoplastic interface problems involving friction, where a nonlinear
uniformly monotone operator such as the p-Laplacian is coupled to the linear
Laplace equation on the exterior domain. The problem is reduced to a
boundary/domain variational inequality, a discretized saddle point formulation
of which is then solved using the Uzawa algorithm and adaptive mesh refinements
based on a gradient recovery scheme. The Galerkin approximations are shown to
converge to the unique solution of the variational problem in a suitable
product of L^p- and L^2-Sobolev spaces.Comment: 27 pages, 3 figure
On the averaging principle for one-frequency systems. Seminorm estimates for the error
We extend some previous results of our work [1] on the error of the averaging
method, in the one-frequency case. The new error estimates apply to any
separating family of seminorms on the space of the actions; they generalize our
previous estimates in terms of the Euclidean norm. For example, one can use the
new approach to get separate error estimates for each action coordinate. An
application to rigid body under damping is presented. In a companion paper [2],
the same method will be applied to the motion of a satellite around an oblate
planet.Comment: LaTeX, 23 pages, 4 figures. The final version published in Nonlinear
Dynamic
Design of a fault tolerant airborne digital computer. Volume 2: Computational requirements and technology
This final report summarizes the work on the design of a fault tolerant digital computer for aircraft. Volume 2 is composed of two parts. Part 1 is concerned with the computational requirements associated with an advanced commercial aircraft. Part 2 reviews the technology that will be available for the implementation of the computer in the 1975-1985 period. With regard to the computation task 26 computations have been categorized according to computational load, memory requirements, criticality, permitted down-time, and the need to save data in order to effect a roll-back. The technology part stresses the impact of large scale integration (LSI) on the realization of logic and memory. Also considered was module interconnection possibilities so as to minimize fault propagation
High-Temperature Optical Constants of Dust Analogues for the Solar Nebula
The dust in protoplanetary disks is influenced by a lot of different
processes. Besides others, heating processes are the most important ones: they
change not only the physical and chemical properties of dust particles, but
also their emission spectra. In order to compare observed infrared spectra of
young stellar systems with laboratory data of hot (up to 700{\deg}C)
circumstellar dust analogues, we investigate materials, which are important
constituents of dust in protoplanetary disks. We calculated the optical
constants by means of a simple Lorentzian oscillator fit and apply them to
simulations of small-particle emission spectra in order to compare our results
with real astronomical spectra of AGB-stars and protoplanetary disks.Comment: 4 pages, 3 figures, Contribution for the ECLA proceedings (European
Conference on Laboratory Astrophysics
Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations
In September 2011, the Herschel Space Observatory performed an observation
campaign with the PACS photometer observing the asteroid (101955) 1999 RQ36 in
the far infrared. The Herschel observations were analysed, together with ESO
VLT-VISIR and Spitzer-IRS data, by means of a thermophysical model in order to
derive the physical properties of 1999 RQ36. We find the asteroid has an
effective diameter in the range 480 to 511 m, a slightly elongated shape with a
semi-major axis ratio of a/b=1.04, a geometric albedo of 0.045 +0.015/-0.012,
and a retrograde rotation with a spin vector between -70 and -90 deg ecliptic
latitude. The thermal emission at wavelengths below 12 micron -originating in
the hot sub-solar region- shows that there may be large variations in roughness
on the surface along the equatorial zone of 1999 RQ36, but further measurements
are required for final proof. We determine that the asteroid has a
disk-averaged thermal inertia of Gamma = 650 Jm-2s-0.5K-1 with a 3-sigma
confidence range of 350 to 950 Jm-2s-0.5K-1, equivalent to what is observed for
25143 Itokawa and suggestive that 1999 RQ36 has a similar surface texture and
may also be a rubble-pile in nature. The low albedo indicates that 1999 RQ36
very likely contains primitive volatile-rich material, consistent with its
spectral type, and that it is an ideal target for the OSIRIS-REx sample return
mission.Comment: Accepted for publication in Astronomy & Astrophysics, 9 pages, 7
figure
Ellipsometric measurements by use of photon pairs generated by spontaneous parametric down-conversion
We present a novel interferometric technique for performing ellipsometric
measurements. This technique relies on the use of a non-classical optical
source, namely, polarization-entangled twin photons generated by spontaneous
parametric down-conversion from a nonlinear crystal, in conjunction with a
coincidence-detection scheme. Ellipsometric measurements acquired with this
scheme are absolute; i.e., they do not require source and detector calibration.Comment: 10 pages, accepted for publication in Optics Letter
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