A physically based model of the year-round surface energy and mass balance of debris-covered glaciers

Debris-covered glaciers respond to atmospheric conditions in different ways from debris-free glaciers, due to the presence of debris at the surface during the ablation season and at the snow/ice interface during the accumulation season. Understanding the response of debris-covered glaciers to a variety of meteorological conditions in a physically sound manner is essential to quantify meltwater discharge and to predict their response to climate change. To tackle this issue, we developed the Crocus-DEB model as an adaptation of the detailed snowpack model Crocus, to simulate the energy and mass balance of debris-covered glaciers, including periods when debris is covered by snow. Crocus-DEB was evaluated with data gathered during a field experiment using artificial debris covering the snowpack at Col de Porte, France, with very good results in terms of conductive heat flux, both at the surface and at the interface between the debris and the underlying dense snow taken as a surrogate for ice, with and without snow overlying the debris. The model was also evaluated using field data from the debris-covered glacier Changri Nup, Nepal, Himalaya. This paper introduces the design of the model, its performance and its ability to explore relationships between model parameters, meteorological conditions and the critical debris thickness.

Single Phase Pressure-Drop Tests in 7-Element Bundles With Different Endplug Shapes

Pressure-drop characteristics in CANDU® fuel bundles are of importance for critical power analysis and safety trip analysis for the reactor core. Different kinds of endplug shapes are being used in different fuel designs. The difference in endplug shape may result in slightly different hydraulic characteristics of the fuel bundles. Single-phase pressure-drop tests were performed in aligned and misaligned (15° and 30°) 7-element bundle strings with three different endplug shapes (Type 1, 2 and 3): Type 1 and 3 with round surface, and Type 2 with flat surface. The test results showed that the bundle-loss coefficients of the misaligned bundle with Type 2 having flat surface presented the highest value among the three-endplug types: 8.6% higher on average, compared to those of the misaligned bundle with Type 1 endplugs (Type 1 as a reference).

Stochastic Characterization of Macro- and Microerrors of Journal Bearing Roundness

A new approach for the characterization of form error and surface roughness of round bearings is presented. The method employs the theory of random function excursions to describe the macro- and microerrors of the round surface in both radial and circumferential directions. The mathematical principle of the measuring technique is given, and it is shown that an accurate description of the roundness can be obtained from the knowledge of the intercept probabilities of the crest and valley excursions of the surface trace about a given reference circle. Based on the mathematical model, new indices for the characterization of journal bearing roundness are proposed. These indices are computed directly from data obtained from commercially available roundness measuring devices. A number of experiments were performed to justify the validity of the proposed roundness indices. Roundness measurements were carried out on a number of differently machined cylinders using a specially equipped measuring device (Talyrond 51) with a link to a hybrid computer EAI-690. The theoretically computed indices compared favorably with the measurements made on the actual round surfaces.

ELECTROKINETIC PHENOMENA. II

Two theories which predict different values for the ratio of VE, the electroendosmotic velocity of a liquid past a surface, to Vp, the electric mobility of a particle of the same surface through the same liquid are discussed. The theory demanding that See PDF for Equation was supported by certain data of van der Grinten for a glass surface. Re-calculation of van der Grinten's data reveals that the ratio varies between 2.1 and 2.8. These results are in accord with previous data of Abramson. It is pointed out that glass is unsuitable for the investigation. The ratio See PDF for Equation is here determined for a flat surface and particles when both are covered by the same proteins. Under these conditions See PDF for Equation The theory is similarly tested for a round surface using a micro-cataphoresis cell. It is shown that See PDF for Equation for a round surface is approximately 1.00. These findings are confirmatory of previous data supporting the view that cataphoretic mobility is independent of the size and shape of the particles when all particles compared have similar surface constitutions.

Experiments on wootz

The fine cakes of the kind of steel called Wootz, which form the subject of the present paper, were delivered to Mr. Mushet, for the purpose of examination, by Sir Joseph Banks. Mr. Mushet begins his account of them by giving a very minute description of the form, the grain, and every other external character of these cakes. This description cannot well be abridged, and is too long to be repeated. We shall therefore only say that Mr. Mushet states, as a general remark, that the grain and density of these cakes of wootz were uniformly homogeneous, and free from metallic iron towards the under or round surface, but that they were always the reverse towards the upper side, called by Mr. Mushet the feeder. The appearances observed upon forging these cakes are then par­ticularly described, from which Mr. Mushet deduces the following general remarks.