We investigate the acceleration and simultaneous radiative losses of electrons in the vicinity of relativistic shocks. Particles undergo pitch angle diffusion, gaining energy as they cross the shock by the Fermi mechanism and also emitting synchrotron radiation in the ambient magnetic field. A semi-analytic approach is developed which allows us to consider the behaviour of the shape of the spec...

I consider analytically particle acceleration at relativistic shocks, in the limit of pitch angle diffusion and large shock Lorentz factors. The derived energy spectrum index (k = (1 + √ 13)/2 ≈ 2.30), and particle pitch angle distribution at the shock are successfully compared with the results of numerical solutions. This totally analytic derivation is completely independent of the detailed de...

The optimization of the louver angle (θ) and the louver pitch (Lp) for a louver finned and tube heat exchanger was investigated numerically along with a simplified conjugate-gradient method (SCGM). The area reduction ratio relative to a plain surface is the objective function to be maximized. A search for the optimum louver angle (θ) and louver pitch (Lp), ranging from 15°< θ < 40° and 2 mm < L...

A novel technique for the real-time measurement of the magnetic field pitch angle in JET discharges using the motional Stark effect diagnostic is presented. Kalman filtering techniques are adopted to estimate the amplitude of the avalanche photodiode signals' harmonics that are relevant for the pitch angle calculation. The proposed technique {for extended technical details of the generic algori...

The magnetic energy and inductance of current distributions on the surface of a torus are considered. Specifically, we investigate the influence of the aspect ratio of the torus, and of the pitch angle for helical current densities, on the energy. We show that, for a fixed surface area of the torus, the energy experiences a minimum for a certain pitch angle. New analytical relationships are pre...

High accuracy attitude and position determination is very important for underwater gliders. The cross-coupling among three attitude angles (heading angle, pitch angle and roll angle) becomes more serious when pitch or roll motion occurs. This cross-coupling makes attitude angles inaccurate or even erroneous. Therefore, the high accuracy attitude and position determination becomes a difficult pr...

This paper presents a design of pitch controller using Genetic Algorithm (GA) for variable speed wind turbine Doubly Fed Induction Generator (DFIG) . The proposed genetic pitch controller is used to get the proper pitch angle for limiting the mechanical power when the wind speed is greater than the rated wind speed. DFIG is a wound-rotor induction generator where the stator terminals of DFIG ar...

In recent years, individual pitch control has been developed for wind turbines, with the purpose of reducing blade and tower loads. Such algorithms depend on reliable sensor information. The azimuth angle sensor, which positions the wind turbine rotor in its rotation, is quite important. This sensor has to be correct as blade pitch actions should be different at different azimuth angle as the w...

During periods of increased magnetospheric activity , whistler wave emissions have been observed with increased wave amplitudes. We consider a pitch angle diffusion mechanism that is shown to scale with whistler wave amplitude and hence is 'switched on' during these periods of intense activity. We consider the interaction between relativistic electrons and two oppositely directed, parallel prop...