Numerical solution of single mode gyrotron equation

In this paper we study numerical problems arising in solving the single mode gyrotron equation. Using the method of finite differences analytical and numerical solutions are obtained. Quasistationary solutions and corresponding eigenvalues and eigenfunctions of this problem are investigated. Girotrono lygties vienos modos skaitiniai sprendimai Santrauka Straipsnyje nagrinėjami skaitiniai sprendiniai gauti tiriant girotrono lygties vieną modą. Analitiniai ir skaitiniai sprendiniai gauti taikant baigtinių skirtumų metodą. Ištirti kvazistacionarieji sprendiniai ir atitinkamos tokio uždavinio tikrinės reikšmės ir tikrinės funkcijos. First Published Online: 14 Oct 201

Comparison of numerical methods for the problem arising in the gyrotron theory

There are considered some aspects for numerical solving of problem with Robin's boundary conditions arising in the gyrotron theory. The single mode case is carefully investigated. The obtained observations make possible to offer the suitable strategy for the numerical solving of the problem for general system of nonstationary gyrotron oscillations. Skaitinių metodų girotrono teorijos uždaviniuose palyginimas Straipsnyje nagrinėjame girotrono teorijos uždavinių su Robino kraštine sąlyga kai kurie skaitinio sprendimo metodų aspektai. Atidžiai nagrinėjamas vienos modos atvėjis ir gauti pastebėjimai leidžia sudaryti tinkamą skaitinio šio uždavinio sprendimo strategiją bendrajai girotrono lygčių sistemai, aprašančiai jo nestacionarius virpesius. First Published Online: 14 Oct 201

Mathematical Models of Papermaking

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations.&nbsp

A multi-scale GIS and hydrodynamic modelling approach to fish passage assessment: clarence and Shoalhaven Rivers, NSW Australia

Natural barriers such as waterfalls, cascades, rapids and riffles limit the dispersal and in-stream range of migratory fish, yet little is known of the interplay between these gradient dependent landforms, their hydraulic characteristics and flow rates that facilitate fish passage. The resurgence of dam construction in numerous river basins world-wide provides impetus to the development of robust techniques for assessment of the effects of downstream flow regime changes on natural fish passage barriers and associated consequences as to the length of rivers available to migratory species. This paper outlines a multi-scale technique for quantifying the relative magnitude of natural fish passage barriers in river systems and flow rates that facilitate passage by fish. First, a GIS-based approach is used to quantify channel gradients for the length of river or reach under investigation from a high resolution DEM, setting the magnitude of identified passage barriers in a longer context (tens to hundreds of km). Second, LiDAR, topographic and bathymetric survey-based hydrodynamic modelling is used to assess flow rates that can be regarded as facilitating passage across specific barriers identified by the river to reach scale gradient analysis. Examples of multi-scale approaches to fish passage assessment for flood-flow and low-flow passage issues are provided from the Clarence and Shoalhaven Rivers, NSW, Australia. In these river systems, passive acoustic telemetry data on actual movements and migrations by Australian bass (Macquaria novemaculeata) provide a means of validating modelled assessments of flow rates associated with successful fish passage across natural barriers. Analysis of actual fish movements across passage barriers in these river systems indicates that two dimensional hydraulic modelling can usefully quantify flow rates associated with the facilitation of fish passage across natural barriers by a majority of individual fishes for use in management decisions regarding environmental or instream flows