Analysis of spallation based upon statistical microdamage mechanics

A relationship between the cumulative length of microcracks and the amplitude and duration of tensile impulse in spallation was established based on the application of statistical microdamage mechanics, which included a statistical formulation and dynamic laws of microdamage under loading. Since the degrees of spallation, called incipient, intermediate and complete spallation, can be characterized by the cumulative length of microcracks, a physical interpretation of an empirical criterion to spallation was presented.

Oscillatory Flow Induced Hydrodynamic Forces upon a Pipeline near Erosive Sandy Seabed

An experimental study of the properties of hydrodynamic forces upon a marine pipeline is presented in this paper, in the equilibrium scour conditions for various Keulegan-Carpenter numbers and various initial relative gaps between pipeline and the erosive sandy seabed. The tests are conducted in a U-shaped oscillatory water tunnel with a sand box located at the bottom of the test section. According to the experimental results, the maximum horizontal forces on the pipelines with an initial gap to seabed will decrease to some extent due to scouring process. For engineering appliances, it seems safer to estimate wave induced forces on pipelines under the assumption that seabed is plane. However, it should be noticed that great changes would be brought to the frequency properties of lift forces because of the sandy scour beneath the pipeline, which occurs for certain KC numbers.

Characteristics of Laminar and Turbulent Argon Plasma Jets Impinging Normally Upon a Workpiece in Ambient Air

Modeling results are presented concerning the characteristicsoflaminar and turbulentargonplasmajetsimpingingnormally upon a flat plate (workpiece) in ambient air. It is found that the presence of the flat plate significantly enhances the entrainment rate of ambient air into the jets and affects on the flow and temperature fields in the near-plate region of the jets. At comparatively large distances between the plate and the jet inlet, the axial gradients of the plasma parameters in the laminarplasmaimpinging-jets assume values much less than those in the turbulentplasmaimpinging-jets.

Modeling Study of Shrouding Gas Effects on a Laminar Argon Plasma Jet Impinging Upon a Flat Substrate in Air Surroundings

With the laminar plasma materials processing as the research background, modeling study is conducted concerning the effects of argon shroud on the characteristics of the laminar argon plasma jet impinging normally upon a flat substrate located in air surroundings. It is shown that adding shrouding gas is an effective method to reduce and control the entrainment of ambient air into the laminar plasma jet. The shrouding gas flow rate or velocity, the injection slot width and the stand-off distance of the substrate appreciably affect the air contents in the plasma near the substrate surface.

Fishing Long-Fingered Bats (Myotis capaccinii) Prey Regularly upon Exotic Fish

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Plankton associated with medusae of the freshwater jellyfish Craspedacusta sowerbyi (Lankester) in a Thames backwater

Samples of plankton were taken from Broom Water in August 1997 after a sighting of medusae on 11th August. Broom Water is about 8 m wide, and extends 250 m from the main channel of the Thames, above the weir at Teddington. On 11th August medusae were so abundant that it was possible to collect 20 in ten minutes. They were rising to the surface in bright sunlight, then sinking slowly down through the water. Examination of a medusa's tentacles under a microscope revealed the presence of a commensal protozoan, a ciliate Trichodina pediculus. Over 20 species of phytoplankton were found in Broom Water. Most of the species are common and widespread, but it was a surprise to find Errerella bornhemiensis with its characteristic pyramidal colonies, which is a relatively rare species. Zooplankters in Broom Water consisted of Rotifera and Crustacea. Zooplankton is the main food of Craspedacusta and it was found that the crustaceans but not the rotifers did undergo significant changes during the period 11-19th August. The major changes were a big increase in the percentage of cyclopoids, and a marked decrease in Bosmina. This could be because the delicate cuticle of Bosmina is much more susceptible to the stinging cells of the medusae compared with the tougher exoskeleton of the cyclopoid.

I. The effects of variations in certain parameters upon the efficiency of in vivo hemodialysis with a Kiil dialyzer. II. Interfacial structure of concurrent air-water flow in a two-inch diameter horizontal tube.

Part I

Regression analyses are performed on in vivo hemodialysis data for the transfer of creatinine, urea, uric acid and inorganic phosphate to determine the effects of variations in certain parameters on the efficiency of dialysis with a Kiil dialyzer. In calculating the mass transfer rates across the membrane, the effects of cell-plasma mass transfer kinetics are considered. The concept of the effective permeability coefficient for the red cell membrane is introduced to account for these effects. A discussion of the consequences of neglecting cell-plasma kinetics, as has been done to date in the literature, is presented.

A physical model for the Kiil dialyzer is presented in order to calculate the available membrane area for mass transfer, the linear blood and dialysate velocities, and other variables. The equations used to determine the independent variables of the regression analyses are presented. The potential dependent variables in the analyses are discussed.

Regression analyses were carried out considering overall mass-transfer coefficients, dialysances, relative dialysances, and relative permeabilities for each substance as the dependent variables. The independent variables were linear blood velocity, linear dialysate velocity, the pressure difference across the membrane, the elapsed time of dialysis, the blood hematocrit, and the arterial plasma concentrations of each substance transferred. The resulting correlations are tabulated, presented graphically, and discussed. The implications of these correlations are discussed from the viewpoint of a research investigator and from the viewpoint of patient treatment.

Recommendations for further experimental work are presented.

Part II

The interfacial structure of concurrent air-water flow in a two-inch diameter horizontal tube in the wavy flow regime has been measured using resistance wave gages. The median water depth, r.m.s. wave height, wave frequency, extrema frequency, and wave velocity have been measured as functions of air and water flow rates. Reynolds numbers, Froude numbers, Weber numbers, and bulk velocities for each phase may be calculated from these measurements. No theory for wave formation and propagation available in the literature was sufficient to describe these results.

The water surface level distribution generally is not adequately represented as a stationary Gaussian process. Five types of deviation from the Gaussian process function were noted in this work. The presence of the tube walls and the relatively large interfacial shear stresses precludes the use of simple statistical analyses to describe the interfacial structure. A detailed study of the behavior of individual fluid elements near the interface may be necessary to describe adequately wavy two-phase flow in systems similar to the one used in this work.

Influence of money upon the social organization

The extraordinary importance that has been attached to money throughout the ages may be appreciated when such modern writers as Alexander Delmar suggest that the history of money is the history of civilization. While this view is not accepted by most writers of the subject, all are nevertheless agreed that money plays a role of enormous importance in the affairs of men. Even in the classics are found quotations which stress this importance of the pecuniary unit upon ethical as well as economic standards.

Devil's Gate Reservoir and its effect upon Pasadena's water supply

[Intro.] The Devil’s Gate Dam has been of great benefit to Pasadena’s water supply, in that it prevents a large amount of the flood waters of the Arroyo Seco being wasted into the ocean.

Effects of Cow Green Reservoir upon downstream fish populations

Post impoundment observations on the fish populations of the River Tees, downstream from the Cow Green Reservoir were made between 1971 and 1980. Both bullhead (Cottus gobio L.) and brown trout (Salmo trutta L.) population densities increased in the river after impoundment but changes in growth rate were small. Investigations into the stomach contents of the two species reflects the results of other work on increases of benthos in the river. Following regulation there was an increase in the quantity of Ephemerella ignita found in trout stomachs while in the bullhead, regulation caused an increase in the importance of Mollusca and a decrease in importance of Ephemeroptera and Plecoptera.