Fractal formation and ordering in random sequential adsorption

We reveal the fractal nature of patterns arising in random sequential adsorption of particles with continuum power-law size distribution, $P(R)\sim R^{\alpha-1}$, $R \le R_{\rm max}$. We find that the patterns become more and more ordered as $\alpha$ increases, and that the Apollonian packing is obtained at $\alpha \to \infty$ limit. We introduce the entropy production rate as a quantitative criteria of regularity and observe a transition from an irregular regime of the pattern formation to a regular one. We develop a scaling theory that relates kinetic and structural properties of the system.Comment: 4 pages, RevTex, 4 postscript figures. To appear in Phys.Rev.Let

Polydisperse Adsorption: Pattern Formation Kinetics, Fractal Properties, and Transition to Order

We investigate the process of random sequential adsorption of polydisperse particles whose size distribution exhibits a power-law dependence in the small size limit, $P(R)\sim R^{\alpha-1}$. We reveal a relation between pattern formation kinetics and structural properties of arising patterns. We propose a mean-field theory which provides a fair description for sufficiently small $\alpha$. When $\alpha \to \infty$, highly ordered structures locally identical to the Apollonian packing are formed. We introduce a quantitative criterion of the regularity of the pattern formation process. When $\alpha \gg 1$, a sharp transition from irregular to regular pattern formation regime is found to occur near the jamming coverage of standard random sequential adsorption with monodisperse size distribution.Comment: 8 pages, LaTeX, 5 figures, to appear in Phys.Rev.

ДОСЛІДЖЕННЯ ДИНАМІКИ СЕРИЄСНОГО ЕЛЕКТРОДВИГУНА З РІЗНИМИ ІМПУЛЬСНИМИ СХЕМАМИ РЕГУЛЮВАННЯ

The improved scheme of impulsive regulation of series excitation direct current motor was developed. Theimpulsive regulation models for offered and existent schemes were developed, the electro-mechanicalprocesses of electric drive were probed and comparative analysis was presented.Разработана усовершенствованная схема импульсного регулирования двигателя постоянноготока последовательного возбуждения. Для предложенной и существующей схем импульсного регулирования разработаны имитационные модели, с помощью которых исследованы электромеханические процессы тягового электропривода и выполнен их сравнительный анализ.Розроблена вдосконалена схема імпульсного регулювання двигуна постійного струму послідовногозбудження. Для запропонованої і існуючої схем імпульсного регулювання розроблені моделі, за допомогою яких досліджені електромеханічні процеси тягового електроприводу в цих схемах і виконаноїх порівняльний аналіз

The data processing and analysis methods for stratospheric ozone and planetary wave study

We describe the methods and data sources for investigating the stratospheric ozone and planetary waves in the atmosphere in the framework of research provided by our international team. Selected ground-based and satellite instruments for ozone measurements and related reanalyses are described. Examples of data and analysis tools are shown. The technique of planetary wave spectral analysis under conditions of dynamic changes during sudden stratospheric warmings is presented. A brief description of the main results, obtained with the participation of the authors, using combined methods of analysis are considered. We describe procedures for the investigation of a long-term eastward displacement of the zonal ozone minimum over the Antarctic in the spring months, analysis of the spatial and temporal characteristics of the teleconnection between the tropical thermal source and the Antarctic stratosphere, and the creation of the predictive index used for the forecast of possible ozone hole anomalous development in spring months. Examples of application of analysis methods to retrieve the changes in the zonal asymmetry of the Arctic stratopause and features of the annual ozone cycle in connection with zonal ozone asymmetry are discussed

Kinetics of Clustering in Traffic Flows

We study a simple aggregation model that mimics the clustering of traffic on a one-lane roadway. In this model, each ``car'' moves ballistically at its initial velocity until it overtakes the preceding car or cluster. After this encounter, the incident car assumes the velocity of the cluster which it has just joined. The properties of the initial distribution of velocities in the small velocity limit control the long-time properties of the aggregation process. For an initial velocity distribution with a power-law tail at small velocities, \pvim as $v \to 0$, a simple scaling argument shows that the average cluster size grows as n \sim t^{\va} and that the average velocity decays as v \sim t^{-\vb} as $t\to \infty$. We derive an analytical solution for the survival probability of a single car and an asymptotically exact expression for the joint mass-velocity distribution function. We also consider the properties of spatially heterogeneous traffic and the kinetics of traffic clustering in the presence of an input of cars.Comment: 18 pages, Plain TeX, 2 postscript figure

Exact results for nucleation-and-growth in one dimension

We study statistical properties of the Kolmogorov-Avrami-Johnson-Mehl nucleation-and-growth model in one dimension. We obtain exact results for the gap density as well as the island distribution. When all nucleation events occur simultaneously, the island distribution has discontinuous derivatives on the rays x_n(t)=nt, n=1,2,3... We introduce an accelerated growth mechanism where the velocity increases linearly with the island size. We solve for the inter-island gap density and show that the system reaches complete coverage in a finite time and that the near-critical behavior of the system is robust, i.e., it is insensitive to details such as the nucleation mechanism.Comment: 9 pages, revtex, also available from http://arnold.uchicago.edu/~ebn

ДОСЛІДЖЕННЯ ПЕРЕХІДНИХ РЕЖИМІВ ПРИ ПОСЛІДОВНЕ З'ЄДНАННЯ СЕРІЄСНИЙ ЕЛЕКТРОДВИГУНІВ ПОСТІЙНОГО СТРУМУ

The effective anti-skidding system for rolling stock of railways with the traction direct-current motors isoffered and investigated. In the article the model for the investigation of the transient state of the directcurrent motor of series excitation for the series connected motors is presented. The results ofelectromechanical processes modeling happened at skidding of wheel pairs of railway rolling stock aregiven.Предложена и исследована эффективная антибоксовочная система для подвижного состава железных дорог с тяговыми электродвигателями постоянного тока. В статье разработана модель для исследования переходных режимов работы электродвигателей постоянного тока последовательного возбуждения при их последовательном соединении. Приведены результа ты моделирования электромеханических процессов, происходящих при боксовании колесных пар подвижного состава железных дорог.Запропонована та досліджена ефективна протибоксовочна система для рухомого складу залізних доріг з тяговими електродвигунами постійного струму. В статті розроблено модель длядослідження перехідних режимів роботи електродвигунів постійного струму послідовного збудження при їх послідовному з’єднанні. Наведено результати моделювання електромеханічних процесів, які виникають в режимі боксування колесних пар рухомого складу залізних доріг

ИССЛЕДОВАНИЕ ПЕРЕХОДНЫХ РЕЖИМОВ ПРИ ПОСЛЕДОВАТЕЛЬНОМ СОЕДИНЕНИИ СЕРИЕСНЫХ ЭЛЕКТРОДВИГАТЕЛЕЙ ПОСТОЯННОГО ТОКА

Предложена и исследована эффективная антибоксовочная система для подвижного состава железных дорог с тяговыми электродвигателями постоянного тока. В статье разработана модель для исследования переходных режимов работы электродвигателей постоянного тока последовательного возбуждения при их последовательном соединении. Приведены результа ты моделирования электромеханических процессов, происходящих при боксовании колесных пар подвижного состава железных дорог