Simulation of the Output Characteristics of High-Power Helical Traveling-Wave Tubes
A numerical simulator of the interaction processes in helical traveling-wave tubes is developed on the basis of the method of large particles in the 1D approximation with the use of the calculation methods developed previously. The output characteristics (frequency dependences of the output power and gain factor) of high-power traveling wave tubes based on helical slow-wave structures for operation in the C and Ku wave bands are studied theoretically and experimentally. It is shown that the results of numerical simulation are in satisfactory agreement with experimental data.
The physical effects and problems within the scientific direction "Gamma-electronics (γ-electronics)", which studies the interaction of the electron and positron fluxes with the electromagnetic field in the γ-range of wavelengths, as well as problems of production and the prolonged existence of the electron-positron substance (EPS) with extremely high stored energy released in the process of collective slow annihilation have been concidered. We discusses the possible quantum analogues of classical high-power microwave devices in the interaction of charged particles multipath different sign. The basic stages of work, corresponding to the possible experiment in gamma-electronics with streams of electrons and positrons have been indicated.
The paper presents a framework for numerical simulation that allows you to ensure saving of resources due to the numerical selection of the optimal size and temperatures in the preparation of bimetallic castings. Modeling obtained boundary and initial conditions at which the metal parts submelting first layer in the contact area with the second layer and is saved in the unmelted state of the first layer with a thickness of 1.5-2 mm, which is in contact with the mold.
In the present study, issues related to the hydrogeology of the basin of the Volga River from Rybinsk to Cheboksary Reservoir are reviewed and analyzed, evaluation of the current state of hydrogeology reservoirs on various parameters is performed. It is revealed that the erosion processes in the basin of the Gorky Reservoir has an average intensity in comparison with similar processes in the basins of the Rybinsk and Cheboksary reservoirs, but the activity is presented. Particular attention to the processes of erosion and shoreline erosion of the Gorky Reservoir is given. The mathematical and numerical model of the slope stability coefficient is presented.
A new mathematical model of heat transfer in silicon field emission pointed cathode of small dimensions is constructed which permits taking its partial melting into account. This mathematical model is based on the phase field system, i.e., on a contemporary generalization of Stefan-type problems. The approach used by the authors is not purely mathematical but is based on the understanding of the solution structure (construction and study of asymptotic solutions) and computer calculations. The book presents an algorithm for numerical solution of the equations of the obtained mathematical model including its parallel implementation. The results of numerical simulation conclude the book.
The book is intended for specialists in the field of heat transfer and field emission processes and can be useful for senior students and postgraduates.
In the present work the results of different scenario of the cliff of Cape Canaille hypothetic collapse (South of France) are presented. Three scenarios were considered: falling of one block, falling of several blocks in one time and debris flow avalanche. The analysis of the entire scenario was done.
We consider the possibility to replace an electron beam (EB) by a "hot" equivalent capacitance that will make it possible to use "hot" equivalent circuits and long lines for analysis the EB interaction in TWTs. A sheet EB in the field of the in-phase mode of the slow wave excited by coupled impedance electrodes is considered in this paper.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.