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The torque characteristics of variable fill hydraulic dynamometers are investigated, particularly the phenomenon of self-emptying of Froude F type machines under open loop control. An integrated one-dimensional model is adapted from fluid coupling and torque converter theory to cover the steady-state case, and extended to the non-linear open loop dynamic cases by incorporating varying fluid fill and the dynamic governing equations for dynamometers. Two feedback systems are included to predict the closed loop behaviour of the machines. The effect of geometric variations on the steady-state torque capacity of dynamometers is given and the cause of the self-emptying phenomenon determined. It is found that the increase in working compartment fluid pressure with shaft speed leads to the fluid outflow rate becoming greater than the supplied...
At the end of 2012 the proton irradiation facility at the CERN PS [1] will shut down for two years. With this in mind, we have been developing a new ATLAS scanning facility at the University of Birmingham Medical Physics cyclotron. With proton beams of energy approximately 30 MeV, fluences corresponding to those of the upgraded large Hadron Collider (HL-LHC) can be reached conveniently. The facility can be used to irradiate silicon sensors, optical components and mechanical structures (e.g. carbon fibre sandwiches) for the LHC upgrade programme. Irradiations of silicon sensors can be carried out in a temperature controlled cold box that can be scanned through the beam. The facility is described in detail along with the first tests carried out with mini (1 1 cm2) silicon sensors.
The multistep direct reaction theory of Feshbach, Kerman and Koonin (1980) is described in detail and compared with other theories. The results of several analyses of experimental cross-sections are described, and the validity and usefulness of the theory assessed.
In central Veracruz State, Mexico, tephritid fruit fly pupae are commonly attacked by ants, staphylinid beetles, and other predators. Excavations in 2 sites with different soil characteristics revealed that Anastrepha spp. (Diptera: Tephritidae) larvae typically burrowed no >2 cm before pupating and rarely burrowed >5 cm. At 4 field sites, pupae of the most commonly encountered local Anastrepha sp. (A. obliqua, ludens, and striata or fraterculus) were placed on the soil surface and at depths of 2.5 and 5 cm and were subsequently sampled daily for 10 d. Pupae on the surface invariably disappeared at a greater rate than those under the surface. There was no difference in the disappearance rate of pupae buried at 2.5 and 5 cm, suggesting that larvae would gain no benefit by pupating at depths below those encountered in nature. The rate of...
Marine energy in the UK is currently undergoing a period of exponential growth in terms of development and implementation. The current installed tidal energy capacity of around 4MW is expected to rise to provide up to 20% of the UK’s electricity demand by 2050 [5]. With this in mind, there is a huge range of energy devices, all seemingly promoted by their developers as the best method of extracting power from the ocean. Embodied energy is an important aspect of any power producing device or process, and is used to describe the amount of energy required to begin and maintain the process of energy generation. Until a device or process has generated this amount of energy it cannot be said to be a net contributor of energy. This work used Life Cycle Assessment to study four tidal energy devices, representing a cross section of the existing...
Comment: 11 pages, 4 figures, to be published in International Journal of Modern Physics E
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