Laser cleaning of varnish from bog oak surface

The removal of varnish is a very challenging task in the conservation of wooden artifacts. The results of experiments performed to investigate the suitability of lasers for cleaning aged varnish from bog oak wood (ebony) are presented in this paper. Optimal laser parameters for safe and efficient varnish ablation were determined in order to preserve the integrity of the original wooden substrate during the cleaning process. The ablation threshold for varnish and wood damage threshold was examined using Nd:YAG laser (1064, 532 and 355 nm) emitting pulses of nanosecond (8 ns) duration. Results of induced varnish removal and other morphological alterations to the wood surface were investigated by optical microscopy and colorimetry

One method for ordering turbulence measuring places applied to free-convection flow around thermal plant coal mill

The investigations of the turbulence in the flow are one of the most expensive, thus the improvement of existing ones and the research related to the new methods are in continual development. The multidisciplinary approach led to the application of the infrared thermography in the turbulent boundary layer observations with the endpoint goal of energy and cost savings in its early stages. This work presents the use of the industrial type infrared thermography for identification of the turbulent zones in the free convective flow, so far the less investigated problem related to convection heat transfer. It was shown that the transient spot temperature difference, measured on the complex geometry of the real-scale coal ventilation mill, of the Thermal plant “Kostolac B”, by an infrared camera, is a good parameter for identification of the most influenced positions by turbulence. The defined fields with maximal transient temperature difference are in accordance with theory and values calculated by numerical simulations for clean geometry, confirming the assumptions. The described method is also convenient for use in cases when the other methods are not applicable because of the complex geometry, unapproachable, or for the other similar reasons. The results from this work would support the more precise measurements with the research type infrared camera, the other methods for measurements

Biomimicry as a method of the high-speed train aerodynamical designing

Шински транспорт, у односу на остале, иступио је у врх према критеријумима брзине и исплативости услуга. Повећање брзине је условило аеродинамичко дизајмирање возова, ради испуњења захтева енергетске ефикасности, потрошње, заштите животне околине, исплативости и др...The rail transport, in relation to the others, step/out to the top considering criteria of velocity and economy of the service. The increase of the running velocity requested the train aerodinamical designeng, for accomplishing the requests of energy efficiency and consumption, enviromental protection, economy, etc..

Biomimicry as a method of the high-speed train aerodynamical designing

Шински транспорт, у односу на остале, иступио је у врх према критеријумима брзине и исплативости услуга. Повећање брзине је условило аеродинамичко дизајмирање возова, ради испуњења захтева енергетске ефикасности, потрошње, заштите животне околине, исплативости и др...The rail transport, in relation to the others, step/out to the top considering criteria of velocity and economy of the service. The increase of the running velocity requested the train aerodinamical designeng, for accomplishing the requests of energy efficiency and consumption, enviromental protection, economy, etc..

Turbulence investigation in the VTI’s experimental aerodynamics laboratory

Wind tunnels are the aerodynamic laboratories which task is to enable high quality and stabile airflow in controlled volume, a test section, during run time, in order to study the effects of streaming around various aeronautical or nonaeronautical models (airfoils and bluff bodies with complex motorized or robotic constructions). The main requirement that leads to quality and reliable measurement results is a high flow quality in the test section: uniformity of the velocity and pressure fields along and across the test section, low turbulence level and low flow direction angularities or swirling. The knowledge of low parameters enables the exchange of the scientific and technical information, comparison of the experimental results from different wind tunnels and data scaling of the model to the real scale. The turbulence intensity TI significantly affects the wind tunnel results and reduction of turbulence is of the highest importance for the quality measurements. This paper presents the Experimental Aerodynamics Laboratory of the VTI in Belgrade, the equipment and methods of turbulence measurements in the test section stream and around different test models. Wind tunnel facilities maintain equipment and devices for sampling, acquisition and data reduction for various test types, from forces and moment measurements, over the pressure distribution measurements to the advanced measurements, followed with the appropriate flow visualization techniques. The modern instrumentation enables determine flow quality and its influence on tests and measurement results of static and dynamic model characteristics