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Temperature control offers benefits in land‐based marine aquaculture: stock growth rates may be enhanced by heating in winter; mortality rates in summer may be reduced by cooling. However, if the plant is not well designed, temperature control may create very large energy demands. This paper describes the application of temperature control in abalone aquaculture in New Zealand, with a focus on energy considerations in plant design. An abalone farm using a semi‐closed water conditioning system is used as a case study for which an energy model, based on a heat pump system, is developed. The model is used to determine the impact of plant design and tank conditions on the economics of the operation. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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The direct conversion of methane to higher hydrocarbons over a silica-supported Ru catalyst has been investigated via an oxygen free, two-step route. The reaction consists of decomposition of methane over a 3% silica-supp orted Ru catalyst at temperatures
between 400 and 800 K to produce surface carbonaceous species followed by rehydrogenation of these species to higher hydrocarbons at
of 368 K. It was found that the Ru/SiO2 catalyst exhibits a trend similar to that for single-crystal Ru catalysts. However, the temperature at which a maximum in ethane selectivity occurs shifts toward a higher temperature. It was also found that the ethane yield can be optimized by changing the surface carbon coverage. Under optimum conditions a net ethane yield of about 13–15% has been realized. For this two-step reaction sequence, only a few reaction cycles could be operated without intermediate high temperature rehydrogenation and without significant loss in ethane yield. This is attributed to large amounts of inactive carbon that could not be hydrogenated at 368 K. Higher methane partial pressures were found to be desirable for this reaction. The activity of the catalyst could also be maintained at total pressures up to 10 atm. 相似文献
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A. A. Zhukov E. T. Filby A. V. Goncharov M. A. Ghanem P. N. Bartlett R. Boardman H. Fangohr V. V. Metlushko V. Novosad G. Karapetrov P. A. J. de Groot 《Journal of Low Temperature Physics》2005,139(1-2):339-349
Using self-assembly from colloidal suspensions of polystyrene latex spheres we prepared well-ordered templates. By electrochemical
deposition of magnetic and superconducting metals in the pores of such templates highly ordered magnetic and superconducting
anti-dot nano-structures with 3D architectures were created. Further developments of this template preparation method allow
us to obtain dot arrays and even more complicated structures. In magnetic anti-dot arrays we observe a large increase in coercive
field produced by nanoscale (50–1000nm) holes. We also find the coercive field to demonstrate an oscillatory dependence on
film thickness. In magnetic dot arrays we have explored the genesis of 3D magnetic vortices and determined the critical dot
size. Superconducting Pb anti-dot arrays show pronounced Little-Parks oscillations in Tc and matching effects in magnetization and magnetic susceptibility. The spherical shape of the holes results in significantly
reduced pinning strength as compared to standard lithographic samples. Our results demonstrate that self-assembly template
methods are emerging as a viable, low cost route to prepare sub-micron structures. 相似文献
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Software organizations can significantly improve the quality of their output if they have a defined and documented software process, together with the appropriate techniques and tools to measure its effectiveness. Without a defined process it is impossible to measure success or focus on how development capability can be enhanced. To date, a number of software process improvement frameworks have been developed and implemented. However, most of these models have been targeted at large-scale producers. Furthermore, they have applied to companies who use traditional development techniques. Smaller companies and those operating in development areas where speed of delivery is paramount have not, as yet, had process improvement paradigms available for adoption.This study examined the software process in a small company and emerged with the recommendation of the use of the Dynamic Systems Development Method (DSDM) and the Personal Software Process (PSP) for achieving software process improvement. 相似文献