Large Energy Output Research Articles

Nd:glass regenerative amplifier with increased bandwidth and high output energy for chirped pulse amplification systems

We demonstrate a large energy output and a wider output spectral bandwidth from Nd:glass-based regenerative amplifiers. The maximum energy extracted from the regenerative amplifier is 24 mJ with an overall gain of 3.4 x 10(8). The maximum output bandwidth achieved is 4.2 nm FWHM when the input pulse spectral bandwidth is 7 nm FWHM. This was made possible by a new cavity optimization technique.

Evaluation of a photovoltaic energy mechatronics system with a built-in quadratic maximum power point tracking algorithm

The historically high cost of crude oil price is stimulating research into solar (green) energy as an alternative energy source. In general, applications with large solar energy output require a maximum power point tracking (MPPT) algorithm to optimize the power generated by the photovoltaic effect. This work aims to provide a stand-alone solution for solar energy applications by integrating a DC/DC buck converter to a newly developed quadratic MPPT algorithm along with its appropriate software and hardware. The quadratic MPPT method utilizes three previously used duty cycles with their corresponding power outputs. It approaches the maximum value by using a second order polynomial formula, which converges faster than the existing MPPT algorithm. The hardware implementation takes advantage of the real-time controller system from National Instruments, USA. Experimental results have shown that the proposed solar mechatronics system can correctly and effectively track the maximum power point without any difficulties.

Modeling, dynamics and control of process networks with high energy throughput

This paper studies the energy dynamics of process networks and/or staged processes in the presence of large energy input and output flows. A generic model structure is developed for such networks and singular perturbation arguments are used to document that the variables in the energy balance evolve over a short time horizon while the variables in the material balance may exhibit both fast and slow transients. Nonlinear reduced order models for the fast and slow dynamics that can be used for model based controller design are also derived. A high-purity distillation column and a reactor with an external heat exchanger are used as simulation case studies to illustrate the theoretical results.

MULTI-SCALE DYNAMICS OF HIGH ENERGY THROUGHPUT SYSTEMS

The present paper analyzes the energy dynamics of process networks and/or staged processes whereby the material recycle streams interconnecting the units/stages take on the additional role of energy carriers. In the presence of large energy input and output flows, the networks considered are shown to exhibit a dynamic behavior with multiple time scales, with the variables in the energy balance evolving over a short time horizon, and the variables in the material balance exhibiting both fast and slow transients. A singular perturbation analysis is employed for the derivation of reduced order models for the fast and slow dynamics. Finally, an illustrative example and numerical simulation results are presented.

A Theory of Shape-Memory Thin Films with Applications

Shape-memory alloys have the largest energy output per unit volume per cycle of known actuator systems [1]. Unfortunately, they are temperature activated and hence, their frequency is limited in bulk specimens. However, this is overcome in thin films; and hence shape-memory alloys are ideal actuator materials in micromachines[l]. The heart of the shape-memory effect lies in a martensitic phase transformation and the resulting microstructure. It is well-known that microstructure can be significantly different in thin films as compared to bulk materials. In this paper, we report on a theory of single crystal martensitic this films. We show that single crystal films of shape memory material offer interesting possibilities for producing very large deformations, at small scales.

Spiral arms and a supernova-dominated interstellar medium

Models of the interstellar medium (ISM) utilizing the large energy output of supernovae to determine the average kinematical properties of the gas, are subjected to an imposed (spiral) density wave. The consequent appearance of the ISM is considered. In particular the McKee–Ostriker model with cloud evaporation is used, but it is shown that the overall appearance of the galaxy model does not change significantly if a modification of Cox's mechanism, with no cloud evaporation, is incorporated. We find that a spiral density wave shock can only be self-sustaining if quite restrictive conditions are imposed on the values of the galactic supernova rate and the mean interstellar gas density.

Confinement of thermonuclear microexplosions in imploding vortices

PRESENT efforts towards laser induced fusion envision spherical pellets consisting of the thermonuclear material in the centre, surrounded by a shell of some inert pusher material and an outer ablator shell. The same principles for the pellet design can be used if the implosion process is induced by a relativistic electron beam or intense ion beam (ref. 1, papers presented to Fifth IAEA Conference, Tokyo, 1974 and J. W. Shearer, unpublished). At least one other design of a non-spherical fuel pellet has been published2. This is non-symmetric and would have the advantage of using just one laser beam for target bombardment. But in all of these designs there remains one principal difficulty: laser, electron or ion beams with a sufficiently large total energy output for high density pellet compression and efficient thermonuclear burn have a comparatively long pulse length. Therefore, in order to use these beams for the required high density pellet compression rather large aspect ratios r/Δr (r=pellet radius, Δr=thickness of pusher and ablator material) are dictated. These may result in rapidly growing Taylor-type instabilities. The growth rate for these instabilities could in principle be reduced below dangerous levels by making the pellet and implosion process highly symmetrical. But, since the symmetry requirements are extreme this may be difficult to achieve. The growth rate for the Taylor instabilities could also be reduced by smaller aspect ratios, but smaller aspect ratios need shorter and precisely shaped pulses, which again are difficult to achieve.

Evidence for the Occurrence of Violent Events in the Nuclei of Galaxies

A number of phenomena, all associated with the nuclei of galaxies, which may suggest that in these nuclei there may take place violent events manifested by a very large energy output and a time scale as short as 10/sup 6/ years, are investigated. Optical and radio data that lead to these conclusions are analyzed. (C.E.S.)