Results 1 - 10 of 1707
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[en] Discrete repairable degradation systems can be modeled by a homogeneous discrete-time second-order semi-Markov chain with finite state space for theoretical and practical sake. In the present paper, the state space can be divided into three subclasses, namely excellent states, good states (middle states) and failure states. The transitions among states may be driven by degradations and inside shocks of the system, repair actions, self-healings, energy supplement and other recovery ways. The Z-transform is used to give distributions for some interesting problems such as distributions of an I-period (oscillation & working time) and a gap between I-periods, and instantaneous and steady availabilities of the system. Finally, some numerical examples are given to illustrate the results obtained in the paper. The work may be used in reliability and maintenance analysis of discrete time repairable systems. - Highlights: • We investigate a repairable aggregated semi-Markov ternary system second-order in state. • The working time omission problem in which oscillation and working period are given is considered. • Some distributions for I-periods, oscillations, working periods and gaps are given by using the Z-transform. • Instantaneous and steady availabilities of the system are presented
[en] Waste-to-energy projects are going ahead in the U.K., they are being project financed and they will make a valuable contribution to environmentally acceptable waste disposal and clean energy within the U.K. Starting from the premise that project sponsors must compete for funds therefore behoves the project sponsor to adapt his proposal to the needs of the investor rather than the other way around. Some of the major potential suppliers of funds are briefly surveyed. It is concluded that waste-to-energy projects do not fit easily into the business plans of venture capital companies, pension funds and banks. Projects must be reworked so that a more favourable opportunity can be offered to potential funders. Ways of achieving this through improved economics and reductions in risk and uncertainty are examined. (author)
[en] The beam envelope equation has been used to address the beam dynamics in rf photoinjectors. A special solution of the envelope equation, known as the invariant envelope, plays a critical role in the theory of emittance compensation. In this comment, I will present a different view of the invariant envelope solution that better delineates its properties and simplifies the picture of beam dynamics.
[en] A new type of power supply system for a gyrotron with collector potential depression (CPD) to enhance gyrotron efficiency was developed. The power supply system is composed of a main power supply (MPS) and an acceleration power supply (APS). The APS which provides the stable high field to the magnetron injection gun (MIG) of the gyrotron is the key point of the system. The DC-DC converter technique is applied to the APS and it can output 100 kV of maximum voltage within ±0.5% stability and 300 mA of maximum current. The CPD gyrotron operation was successfully achieved with an efficiency of 48% and power of 350 kW for 5 s at 110 GHz. The stable gyrotron operation, without regulation of MPS, which provides the d.c. input power to the gyrotron, has been demonstrated by the combination of the APS and MPS. (orig.)
[en] Recently a dual-axis energy recovery linac has been proposed for ERL applications, in which accelerating and decelerating beams can go through separate axes but still recover energy in novel dual-axis cavities. Here we discuss a conceptual design of a 5-cell dual-axis cavity evolved from side-by-side jointed TESLA-type cavities. Instead of an engineering design, we aim to explore the feasibility of such a new cavity, giving particular attention to its nonstandard features that might cause concern to the beam. This is a preliminary work-in-progress report.
[en] The first stage of the Novosibirsk high-power free-electron laser (FEL) was commissioned in 2003. It is driven by a CW energy recovery linac. The next step will be the full-scale machine, a four-track accelerator-recuperator based on the same RF accelerating structure. This upgrade will permit to get shorter wavelengths in the infrared region and increase the average power of the FEL by several times. The scheme and some technical details of the project are set out. The installation will be a prototype for future multiturn accelerator-recuperators.
[en] Miscanthus 'Giganteus' is a perennial C4 grass from East Asia. The biomass yield-potential of Miscanthus has been investigated in Germany since 1987. The combustion of biomass offers a possibility for lowering emissions of the greenhouse gas CO2. The CO2 which is set free during combustion has previously been fixed by the plants. The study analyses the demand for energy and the CO2 -emissions which are involved in the production of Miscanthus, beginning with propagating the plants to transporting the biomass to the power station. Energy demand and CO2 -emissions are compared with those of the provision and combustion of hard coal. The energy content of Miscanthus biomass harvested from one hectare, about 20 t of dry matter, corresponds to the energy content of 12 t hard coal. For each gigajoule of hard coal, 96.6 kg CO2 are emitted during provision and combustion. By combusting Miscanthus instead of hard coal 90% of CO2 -emissions can be saved. (Author)
[en] We present multiparameter optimization of an ERL injector. Two approaches, knowledge-based optimization with down-hill simplex and all-at-once optimization with simulated annealing are used. Both approaches show sufficiently good results
[en] The advent of energy recovering linacs opens up a new area in the luminosity / target density plane, allowing for unique experiments both on the intensity and on the precision frontier. In the talk, I give an overview of experiments already funded or proposed. In the second part, ideas for future experiments are discussed.