This paper is devoted to the study of relative structural stability (the roughness) dynamical systems considered not on whole space systems, but only a certain subspace it. Moreover, deformations also does coincide with admissible deformations. In particular, we consider dissipative differential equations that arise in rigid-body dynamics and theory oscillations; dissipation such may by positiv...

Solar air heater is a type of heat exchanger which transforms solar radiation into heat energy. The thermal performance of conventional solar air heater has been found to be poor because of the low convective heat transfer coefficient from the absorber plate to the air. Use of artificial roughness on a surface is an effective technique to enhance the rate of heat transfer. A CFD-based investiga...

considering the importance of adequate roughness coefficient estimation in river engineering studies, evaluation of image processing technique in estimating manning’s roughness coefficient in the surface layer of riverbeds carried out in this study. the mentioned approach evaluation conducted by implementing of sieving analysis and digital image processing methods simultaneously for a 7.5km rea...

The twig bases within the genus Salix were investigated. Brittleness of twig bases as defined in the literature neither correlates with Young's modulus nor with growth strains, which were measured for S. alba, S. fragilis and S. x rubens. For the species S. alba, S. appendiculata, S. eleagnos, S. fragilis, S. purpurea, S. triandra, S. viminalis, and S. x rubens, fracture surfaces of broken twig...

An air–sea interaction model that includes turbulent transport due to capillary waves (surface ripples) is developed. The model differs from others in that the physical premises are applicable to low wind speeds (10-m wind speed, U10 , 5 m s21) as well as higher wind speeds. Another new feature of the model is an anisotropic roughness length, which allows a crosswind component of the stress to ...

The Colorado State University standard mesoscale model is used to evaluate the sensitivity of one-dimensional (1D) and two-dimensional (2D) fields to differences in surface-layer parameterization “constants”. Such differences reflect the range in the published values of the von Karman constant, Monin-Obukhov stability functions and the temperature roughness length at the surface. The sensitivit...

Various studies investigating the future impacts of integrating high levels of renewable energy make use of historical meteorological (met) station data to produce estimates of future generation. Hourly means of 10m horizontal wind are extrapolated to a standard turbine hub height using the wind profile power or log law and used to simulate the hypothetical power output of a turbine at that loc...

One of the most important resources available in the field of fluid mechanics, the Moody Chart gives Darcy friction factor as a function of Reynolds number and relative roughness. The experimentalists who generated the data correlated in the Moody Chart, however, roughened pipe surfaces by coating their internal surfaces with a monolayer of sand, the pipe wall roughness being defined as the ave...

Scraping a surface with the finger tip is a multimodal event. We obtain information about the texture, i.e. roughness of the surface, at least through three different sensory channels, i.e. auditory, tactile and visual. People are highly skilled in using touch-produced sounds to identify texture properties. Sound pressure level, modulation frequency and pitch of the touch-induced scraping sound...