Introduction to physical acoustics

The book gives a concise account of physical acoustics – a branch of physics studying the interaction of acoustic waves with matter at the macro and microscopic levels. It starts with the basics of mechanics of continuum needed to analyse the problems of physical acoustics. This is followed by the description of linear and nonlinear problems of acoustics of gases, liquids and solids. Also considered are the problems of ‘turbulence and sound’, acoustics of magnetic media, and acoustics of crystals. Important information is provided also on acousto-electronics and acousto-optics. Some parts of the book are illustrated by description of the methodology of experiments and experimental data. The book would be of interest to undergraduate students of physical, chemical and engineering specialities, postgraduate students, researchers, lecturers, acoustic engineers, and all those engaged in fluid mechanics, elasticity, solid state physics, radio physics, signal processing, underwater acoustics and geophysics. (Abstract translated from the Russian)

Surface acoustic waves

The book describes surface acoustic waves in solids, one of the most interesting and important types of wave motion. Classification of the main currently known types of surface acoustic waves is given. Their physical properties, including the specifics of propagation, scattering, and interaction with electrons, are discussed. Much of attention is paid to surface waves in piezoelectric crystals, which play a particularly important role with regard to a variety of applications in signal processing devices. There are numerous examples illustrating various manifestations of surface acoustic waves in science and engineering

Model of the evolution of acoustic emission as the randomization of transient processes in coupled nonlinear oscillators

The behavior of a crack as a resonator radiating acoustic emission (AE) pulses at instants of sudden growth is investigated theoretically and experimentally. This resonance behavior of a growing crack is determined to a large extent by surface waves propagating along its edges. The crack can therefore be regarded as an acoustic resonator excited at the instant of growth of its tip. Transformations in the form of high-frequency harmonic and combination-frequency subharmonic generation are observed in the spectra of the AE signals. The final stage in the evolution of AE is characterized by the transition to a wideband noise spectrum. These facts lead to the hypothesis that bifurcations analogous to those encountered in the onset of dynamic chaos take place in the AE process. This hypothesis forms the basis of a mathematical model of the AE process as a system of coupled nonlinear oscillators, each corresponding to an individual crack. The initial displacement in one of the interacting cracks is adopted as the bifurcation parameter. Spectra calculated by computer simulation exhibit qualitative agreement with the evolution of the spectra obtained in the processing of data from physical experiments

Features of independent physical training students of the departmental institute of the Federal Penitentiary Service of Russia in the conditions of distance learning

The article discusses issues related to the features and problems of independent physical training of cadets of the departmental educational organization of the Federal Penitentiary Service (FSIN) of Russia in the context of distance learning caused by the coronavirus pandemic. The results of a survey of 100 cadets of the Vologda Institute of Law and Economics of the Federal Penitentiary Service of Russia showed that about 27% of the surveyed students did not have sufficient opportunity to visit sports facilities during the period of self-isolation and distance learning. Also, in addition to objective conditions, the psychological and emotional state of students is of no small importance. The problems of physical training considered in the article that arise among students during the period of distance learning are of a complex nature and require an equally integrated approach for their solution, which involves: legal and organizational support for sports in self-isolation, as well as psychological support of students in distance learning.В статье рассматриваются вопросы, касающиеся особенностей и проблем самостоятельной физической подготовки курсантов ведомственной образовательной организации Федеральной службы исполнения наказаний (ФСИН) России в условиях дистанционного обучения, обусловленных пандемией коронавирусной инфекции. Результаты опроса 100 курсантов Вологодского института права и экономики ФСИН России показли, что около 27% опрошенных обучающихся не имели достаточной возможности посещать спортивные объекты в период самоизоляции и дистанционного обучения. Также, помимо объективных условий, немаловажное значение имеет психологическое и эмоциональное состояние обучающихся. ассматриваемые в статье проблемы физической подготовки, возникающие у обучающихся в период дистанционного обучения, имеют комплексный характер и требуют столь же комплексного подхода для их решения, предполагающего: правовое и организационное обеспечение занятия спортом в условиях самоизоляции, а также психологическое сопровождение обучающихся при дистанционной форме обучения

Unsupervised Classification of SAR Images using Hierarchical Agglomeration and EM

We implement an unsupervised classification algorithm for high resolution Synthetic Aperture Radar (SAR) images. The foundation of algorithm is based on Classification Expectation-Maximization (CEM). To get rid of two drawbacks of EM type algorithms, namely the initialization and the model order selection, we combine the CEM algorithm with the hierarchical agglomeration strategy and a model order selection criterion called Integrated Completed Likelihood (ICL). We exploit amplitude statistics in a Finite Mixture Model (FMM), and a Multinomial Logistic (MnL) latent class label model for a mixture density to obtain spatially smooth class segments. We test our algorithm on TerraSAR-X data

Comissioning of the linear accelerator-injector at the TNK facility

The industrial storage facility has been developed and manufactured at the Budker INP SB RAS. It contains an 80 MeV electron linear accelerator-injector and two electron storage rings: the lesser 450 MeV booster ring and the main 2.5 GeV storage ring. In 2002, the work on the accelerator assembling was begun. On December, 25 this year the accelerator was started up, and the current at the linear accelerator output was obtained. The linear accelerator schematic together with a description of the 6 meter long accelerating DAW structure which operates at 2.8 GHz, are presented in the paper. The first results of the accelerator start-up are as follows: the accelerated electron current of ~50 mA with the energy of ~55...60 MeV.Технологічний накопичувальний комплекс був спроектований і виготовлений у ІЯФ ім. Г.І. Будкера СВ РАН. Він містить у собі інжектор–лінійний прискорювач електронів з енергією до 80 МеВ і два накопичувачі електронів: малий накопичувач–бустер на енергію 450 МеВ і основний накопичувач на енергію 2.5 ГеВ. Приводяться функціональна схема лінійного прискорювача й опис конструкції прискорюючої структури із шайбами і діафрагмами довжиною 6 м, що працює на частоті 2.8 ГГц.Представлено перші результати запуску прискорювача: отриманий прискорений струм електронів ~50 мА з енергією ~(55...60) МеВ.Технологический накопительный комплекс был спроектирован и изготовлен в ИЯФ им. Г.И. Будкера СО РАН. Он включает в себя инжектор–линейный ускоритель электронов с энергией до 80 МэВ и два накопителя электронов: малый накопитель–бустер на энергию 450 МэВ и основной накопитель на энергию 2.5 ГэВ. Приводятся функциональная схема линейного ускорителя и описание конструкции ускоряющей структуры с шайбами и диафрагмами длиной 6 метров, работающей на частоте 2.8 ГГц. Представлены первые результаты запуска ускорителя: получен ускоренный ток электронов ~50 мA с энергией ~(55...60) МэВ