864 research outputs found
Limit theorems for random point measures generated by cooperative sequential adsorption
We consider a finite sequence of random points in a finite domain of a
finite-dimensional Euclidean space. The points are sequentially allocated in
the domain according to a model of cooperative sequential adsorption. The main
peculiarity of the model is that the probability distribution of a point
depends on previously allocated points. We assume that the dependence vanishes
as the concentration of points tends to infinity. Under this assumption the law
of large numbers, the central limit theorem and Poisson approximation are
proved for the generated sequence of random point measures.Comment: 17 page
Concepts of universal time and multiplicity of times in understanding the existence of past reality
The purpose of the article is to identify and determine the dependence of ontological ideas about the existence of past reality on thinking within the framework of competing concepts of universal time and multiplicity of times. The methods of research were the representation, comparison and ontological analysis of various ideas about the essence and nature of time, synthesis and philosophical criticism of the consequences arising from competing concepts of the multiplicity of times and the concept of a single universal time in relation to the definition of ontological characteristics of past reality. The article gives a representation of several versions of the concepts of multiplicity of times, some of which are based on the theory of relativity, others proceed from ontological differences in the processes of various forms of being — being material, spiritual, personal and social. It has been shown that in some cases, in the concepts of multiplicity of times, time itself and the idea of time as a construct of the mind are mistakenly identified, which serves as the reason for the incorrect attribution of time to atypical paradoxical properties, such as inversion — the possibility of its movement to reverse, the uncertainty of the past, present and future, the variability of the past and others. The author gives critical arguments refuting ideas about the possibility of changing the places of events and states of reality in the time relationship “earlier/later,” that is, in the sequence of their appearance and disappearance, as well as incorrect opinions about the possibility of variability of the past under the influence of processes that take place in the present and have to be in the future. The study justifies the idea that a clear and unambiguous distinction between past and present objective reality is impossible from the point of view of ideas about the multiplicity of times and is possible only in the conceptual field of theories, recognizing the unity of the world and using a single scale of universal time common to processes and events, having different ontological characteristics and flowing in arbitrarily distant places of space in different inertial reference systems
Dispersion of Waves in Relativistic Plasmas with Isotropic Particle Distributions
The dispersion laws of Langmuir and transverse waves are calculated in the
relativistic non-magnetized formalism for several isotropic particle
distributions: thermal, power-law, relativistic Lorentzian and hybrid
. For Langmuir waves the parameters of superluminal undamped, subluminal
damped principal and higher modes are determined for a range of distribution
parameters. The undamped and principal damped modes are found to match
smoothly. Principal damped and second damped modes are found not to match
smoothly. The presence of maximum wavenumber is discovered above that no
longitudinal modes formally exist. The higher damped modes are discovered to be
qualitatively different for thermal and certain non-thermal distributions.
Consistently with the known results, the Landau damping is calculated to be
stronger for non-thermal power-law-like distributions. The dispersion law is
obtained for the single undamped transverse mode. The analytic results for the
simplest distributions are provided.Comment: 8 pages, 12 figures, accepted by Physics of Plasma
A model for the distribution of aftershock waiting times
In this work the distribution of inter-occurrence times between earthquakes
in aftershock sequences is analyzed and a model based on a non-homogeneous
Poisson (NHP) process is proposed to quantify the observed scaling. In this
model the generalized Omori's law for the decay of aftershocks is used as a
time-dependent rate in the NHP process. The analytically derived distribution
of inter-occurrence times is applied to several major aftershock sequences in
California to confirm the validity of the proposed hypothesis.Comment: 4 pages, 3 figure
Almost Periodic and Asymptotically Almost Periodic Solutions of Liénard Equations
The aim of this paper is to study the almost periodic and asymptotically almost periodic solutions on (0,+1) of the Li´enard equation
x′′ + f(x)x′ + g(x) = F(t),
where F : T ! R (T = R+ or R) is an almost periodic or asymptotically almost periodic function and g : (a, b) ! R is a strictly decreasing function. We study also this problem for the vectorial Li´enard equation.
We analyze this problem in the framework of general non-autonomous dynamical systems (cocycles). We apply the general results obtained in our early papers [3, 7] to prove the existence of almost periodic (almost automorphic, recurrent, pseudo recurrent) and asymptotically almost periodic (asymptotically almost automorphic, asymptotically recurrent, asymptotically pseudo
recurrent) solutions of Li´enard equations (both scalar and vectorial)
Stator current limiting in variable-frequency electrical drive with scalar control system
The problem of stator current limiting of asynchronous electrical drive under overload is reviewed. Task of research is stated. Mathematical model of simplest scalar control system with current limiter and results of mathematical modeling of electrical drives in stator limiting modes are included.Рассматривается проблема ограничения тока статора асинхронного электропривода при перегрузке. Дается постановка задачи исследования. Приводятся математическая модель простейшей скалярной системы с отсечкой по току и результаты математического моделирования процессов электропривода в режимах ограничения тока статора
Low-frequency hemoviscoelastography in monitoring coagulation disorders after abdominal surgery for cancer
- …