A model for simulating speckle-pattern evolution based on close to reality procedures used in spectral-domain OCT

A robust model for simulating speckle pattern evolution in optical coherence tomography (OCT) depending on the OCT system parameters and tissue deformation is reported. The model is based on application of close to reality procedures used in spectral-domain OCT scanners. It naturally generates images reproducing properties of real images in spectral-domain OCT, including the pixelized structure and finite depth of unambiguous imaging, influence of the optical spectrum shape, dependence on the optical wave frequency and coherence length, influence of the tissue straining, etc. Good agreement with generally accepted speckle features and properties of real OCT images is demonstrated.Comment: 13 pages, 6 figure

Vibrational diagnostics parameters of fatigue damage in elastic bodies

The results of investigations of most sensitive vibration based characteristics of fatigue type damage are presented. The characteristics of damage under consideration were damping and parameters of non-linear effects caused by the change of elastic body stiffness at the instant of crack opening-closure. A closing crack causes the dynamic behaviour of vibrating system to be significantly non-linear. Numerical and experimental investigations of forced vibrations of beams with a closing crack have demonstrated that the main distinctive features of such a vibration system are the manifestation of effects associated with nonlinearity, namely the presence of sub- and super-harmonic resonances and significant nonlinearity of the vibration responses (displacement, acceleration, strain) at sub- and superresonances. The sensitivity of these non-linear effects to the crack presence exceeds many times (one or even two orders of magnitude) the sensitivity of natural frequencies and mode shapes, as well as the sensitivity of non-linear effects at resonance. This opens up the good prospect of using sub- and super-resonance regimes for the diagnosis of fatigue cracks

Designing the setup for testing of a 30 kW steam turbine

In order to investigate a low power steam turbine with a non-standard design, an experimental stand was assembled. The main tasks in the tests are to determine the turbine efficiency and obtain the turbine power dependence on the steam consumption in steady-state conditions. The stand scheme and the equipment characteristics are given. The testing technique is described. Based on obtained results, will be conclusion made about the turbine's preparedness for mass production.С целью исследования паровой турбины малой мощности с нестандартной конструкцией собран экспериментальный стенд. Основными задачами при испытаниях является определение эффективности турбины и получение зависимости мощности турбины от расхода пара в установившихся режимах. Приведена схема стенда и характеристики оборудования. Описана методика проведения испытаний. Основываясь на полученных результатах, будет сделан вывод о готовности турбины к серийному производству

ОСОБЕННОСТИ РАСПРЕДЕЛЕНИЯ «МЕСТНОГО» (ГРУНТОВОГО) РАДОНА В ПОЧВЕННОМ ВОЗДУХЕ ПОКРОВНЫХ ОТЛОЖЕНИЙ БЕЛАРУСИ

Five types of territories differing in the values of the volume activity of the «local» (earth) radon and in the degree of their radon hazard have been distinguished within the soil air region.Охарактеризован радонопродуцирующий потенциал основных генетических типов покровных отложений. По этим данным с использованием карты четвертичных отложений построена схема, на которой выделено пять типов территорий, различающихся по значениям объемной активности «местного» (грунтового) радона в почвенном воздухе. Выполнена оценка степени радоноопасности этих типов территорий, которые подразделены на относительно безопасные, потенциально опасные на локальных участках, потенциально опасные на отдельных площадях и потенциально опасные