Showing papers on "Water environment published in 1975"

An assessment of techniques for hydrothermal prediction. Technical report

Abstract: The report provides a critical assessment of techniques - both mathematical models and experimental methods - to predict temperature distribution in the water environment resulting from waste heat releases from steam-electric generation. Such predictions constitute an integral part of environmental impact assessment of power plant facilities. Different types of receiving waters and discharge modes are discussed. Types of receiving waters include lakes, rivers, estuaries, coastal waters and cooling ponds; discharge modes are surface and submerged discharges. Mathematical models are evaluated in regard to their physical validity, degree of field or laboratory verification and computational utility. (GRA)

The accuracy of diver sound localization by pointing

Abstract: The accuracy of human sound localization in 360 degrees of azimuth was determined underwater in a free field. The location indicator was a pointer in the median plane. Accuracy of the response was defined as the mean deviation (MD) from the objective location of a sound source. Maximum accuracy obtained using the present procedure with visual cues was approximately 6 degrees, while maximum accuracy with auditory cues was approximately 11 degrees. Training with visual feedback resulted in a reduction in errors due to the pointing procedure employed, but did not affect localization accuracy. The decrement in accuracy of auditory localization found in the water environment should have no noticeable effect on the ability of divers to find a sound source in the environment.

Surface damage and environmental effects on the strain-rate sensitivity of the strength of sapphire and silicon carbide filaments

Abstract: c-axis sapphire and silicon carbide-on-carbon filaments with pristine and damaged surfaces were tensile tested in water and dry toluene at various strain rates. There was no evidence of slow crack growth during the testing of the silicon carbide filaments. However, the surface damaged sapphire filaments exhibited slow crack growth in the water environment. The slope of the stress intensity factor versus crack velocity curve in region I of the characteristic curve was found to be 28 in excellent agreement with previous results from slow crack growth studies in which the stress corrosion phenomenon is adequately explained by the Hillig-Charles mechanism. The corresponding tests in dry toluene produced no evidence of slow crack growth. The sapphire filaments with virgin surfaces exhibited slow crack growth in both water and toluene which is apparently not related to the moisture assisted growth observed in the abraded filaments.

Heat disposal in water environment

Abstract: The need for continuing development of techniques for predicting temperature distributions due to waste heat discharges into lakes, rivers, estuaries, and the oceans is presented. Diffusion of buoyant jets is examined, including heated surface jets and multiple jets issuing from a submerged multiport diffuser. In the near-field analysis of surface jets the important problems are related to the lateral spreading caused by buoyancy. Comparison of theoretical predictions with laboratory and field observations are given. The mechanics of multiport diffusers for heated discharges in shallow receiving waters are explained in contrast to sewage diffusers. The important problem is the degree to which stratification can be maintained in order to minimize local reintrainment and reduction of dilution capacity. Criteria for stable and unstable flow regimes are provided. A mathematical model for temperature distribution, with or without waste heat addition, in unsteady flows under time-varying meteorological conditions is given.

Underwater welding and cutting

Abstract: The paper first discusses the present status of underwater welding research and development efforts carried in various laboratories in the world and how the research at Massachusetts Institute of Technology fits into the total picture. The paper then describes the three-year research program entitled "Fundamental Research on Underwater Welding" conducted from July 1971 to June 1974 at M.I.T. for the National Sea Grant Office. The program covered the following phases: Phase I: Survey of fundamental information on underwater welding and cutting. Phase 2: A study of heat flow during underwater welding. Phase 3: Mechanisms of metal transfer in underwater welding. Phase 4: Effects of water environment on metallurgical structures and properties of welds. Phase 5: Development of improved underwater welding methods.

Fundamental Research on Underwater Welding Effects of water environment on metallurgical structures of welds

Abstract: The study on which this paper is based was conducted as part of a systematic research on fun­ damentals of underwater welding. The entire program covered various subjects including the heat transfer and flow during underwater welding, the mechanisms of metal transfer and arc bubble formation, and the effects of water environment on the metal­ lurgical structures and the properties of underwater welds. This paper primarily discusses the last subject. An experimental investigation was made of the welding metallurgy and microstructure of underwater shield­ ed metal-arc welds. The paper dis­ cusses various topics including tem­ perature histories and microstruc­ tural transformation, optimum weld­ ing current and speed, optimum weld bead shape, and optimum hardness profiles.

High seas oil recovery systems development and testing

Abstract: The nature of high seas oil spills required the development of special devices which would operate and recover oil in the rough water environment. The importance of fast response to these situations dictated certain size and weight requirements and the oil spills predicted, dicated the recovery rate capability. These specifications are outlines and a history of events leading to the development and test of prototype systems is discussed. Certain of the oil recovery techniques are mentioned. Devices carried to prototype or advanced laboratory model level are discussed. Examples are: the Free Vortex, the Weir-Basin, and the Disc-Drum. Attention is given to the theory of operation of these systems. Oil tests and sea tests of these devices are discussed. The capability of these systems are a result of recent design changes and tests is covered.