Anode surface temperature profile in MPD thrusters

The focus of this study involved the application of an effective methodology to estimate decimal reduction of two main food-borne pathogens (i.e., Salmonella and Listeria) in frozen cooked chicken products using surface pasteurization. A quick and effective approach to estimate the surface temperature of the product was proposed using the Page equation and the evaluation of pathogenic destruction on the large-size and small-size frozen steamed chicken products. The samples were in the frozen form and treated as if they were post-contaminated by Salmonella and Listeria. The pasteurization temperatures in the steam oven were varied at 70, 75, 80, 90 and 100 degree Celsius. The Page equation performed well to accurately predict the surface temperature profile of the different product sizes. The steam treatment was very effective in heating up the pasteurized products and resulted in similar temperature profiles regardless of product size. The relationship between the model constant coefficient and pasteurization temperature followed the Arrhenius expression. The substitution of the predicted surface temperature profile to the process lethality equation facilitated quick estimation of pathogenic destruction on the sample surface. The different sizes of the chicken products only slightly affected the pasteurization time. However, the pasteurization time to achieve that same decimal reduction varied significantly between the two different target pathogens. The simplicity and effectiveness of this approach did not only eliminate multiple experimental repetitions and simplify the estimation of pathogenic destruction, but also provided and effective minimal processing procedure for frozen cooked chicken pasteurization of two sizes of steamed products while retaining the desirable quality of end products after surface pasteurization.

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Interpretation of the Temperature Profile Measured at Vostok, East Antarctica

Annals of Glaciology ◽

10.3189/s0260305500007102 ◽

1989 ◽

Vol 12 ◽

pp. 138-144 ◽

Cited By ~ 12

Author(s):

Catherine Ritz

Keyword(s):

Surface Temperature ◽

Temperature Profile ◽

Accumulation Rate ◽

Ice Core ◽

Measured Temperature ◽

Surface Temperature Change ◽

Subglacial Lake ◽

Polar Ice Sheets ◽

Vostok Station ◽

Geothermal Flux

The temperature profile measured in the Vostok bore hole is analysed. The temperature distribution in polar ice sheets depends mainly on past surface temperature, geothermal flux, and accumulation rate. In the present work, the heat equation is solved both for ice and for the underlying bedrock. The Vostok ice core offers a 160 000 year climatic record which is used to define the past surface temperature, while accumulation-rate variations are assumed to be governed by the saturation vapour pressure. The model is run for a number of different sets of parameters in order to find the parameter associations giving a good fit between the observed and the computed temperature profiles. With this model, it is possible to simulate the measured temperature profile within 0.1°C. To obtain this good fit, geothermal flux has to be higher than 50 mW/m2 and present-day accumulation rate must be lower than 2.6 cm/year. Sensitivity of these results both to the amplitude of surface-temperature change and to the velocity profile with depth is also investigated. Finally, it is shown that ice is at the melting point at the base of the ice sheet, which is in agreement with the presence of a subglacial lake near Vostok Station.

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