Minimum weight design of axially compressed ring and stringer stiffened cylindrical shells

Minimum weight design of axially compressed ring and stringer stiffened cylindrical shell

Energy-Saving Adaptive Robust Motion Control of Single-Rod

This paper studies the energy-saving adaptive robust motion control of a single-rod hydraulic cylinder through the use of programmable valves. The programmable valve used in this study is a unique combination of five proportional cartridge valves connected in such a way that the meter-in and meter-out flows can be independently controlled by four of the valves as well as a true cross port flow controlled by the fifth valve. The programmable valve decouples the meter-in and meter-out flows which in turn allows tremendous control flexibility. Although at the expense of controller complexity, if well utilized, the added control flexibility can be used to significantly reduce the fluid power energy usage in a number of motion and loading conditions to meet the society 's need for energy conservation while without sacrificing the achievable motion control accuracy. Such an coordinated control solution is provided in the paper, and is shown effective through both the simulation and experimental results in the likely operating conditions of a typical industrial backhoe loader arm

Tuu tuu tupakkarulla (2/4 G)

Laulun sanat: Tuu tuu tupakkarulla, Mistäs tiesit tänne tulla, Pitkän pellon pyörtänöltä

Numerical Modeling and Experiments of Periodic Waves Shoaling Over

We study the propagation of long periodic waves over semi-buried cylindrical objects in the bottom. We present a combination of laboratory wave tank experiments, with a sandy bottom, and numerical modeling, using a two-dimensional fully nonlinear potential flow model. Experiments provide wave elevation at gages and velocity fields measured around the semi-buried objects, using anAcoustic DopplerVelocimetry (ADV) method. The model is run for the same geometry and wave parameters as in the experiments. A numerical absorbing beach is used to both prevent waves from overturning and specify wave absorption in the model surfzone. Bottom friction in the shoaling region is specified as a corresponding energy loss in the model, by using an absorbing surface pressure. Without the semi-buried cylinder, the comparison between computed and experimental results is quite good for both surface elevation and near bottom velocities, even for waves near the breaking point. Strong asymmetry is observed for the bottom velocities under nonlinear shoaling waves, with respect to the front and rear of the waves, and with respect to wave elevations from mean water level. These velocities are compared to standard predcitions of linear wave theory and differences are discussed. With the cylinder, the agreement of computed and measured velocities close to the cylinder is also good, except, just in front and behind the cylinder, likely due to vortex shedding. The model can thus be used to accurately provide background wave fields around the buried object, say, at one diameter away. Based on these, more refined hydrodynamic and sediment transport modeling can be performed in future studies