High temperature deformation of dispersion strengthened nickel alloys. 1 - The influence of initial structure on tensile and creep deformation of TD nickel. 2 - The effect of matrix stacking fault energy on creep of Ni-Cr-ThO2 alloys Final report, 9 Feb. 1967 - 9 Feb. 1968

High temperature creep studies on unaltered, and recrystallized nickel alloy

The role of grain size and shape in the strengthening of dispersion hardened nickel alloys

Thermomechanical processing was used to develop various microsstructures in Ni, Ni-2ThO2, Ni-20Cr, Ni-20CR-2ThO2, Ni-20Cr-10W-and Ni-20Cr-10W-2ThO2. The yield strength at 25 C increased with substructure refinement according to the Hall-Petch relation, and substructure refinement was a much more potent means of strengthening than was dispersion hardening. At elevated temperature (1093 C), the most important microstructural feature affecting strength was the grain aspect ratio (grain length, L, divided by grain width, 1. The yield strength and creep strength increased linearly with increasing L/1

Science leadership for tomorrow: The role of schools of public affairs and universities in meeting needs of public science agencies

Recommendations and requirements for the preparation of personnel with some scientific or technological background to enter fields of public policy and administration are reported. University efforts to provide science administration graduate programs are outlined and increased cooperation between government and university resources is outlined

175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser

We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 µm thick intracavity single crystal diamond heat spreader in thermal contact with the front surface of the gain sample using liquid capillary bonding. The repetition frequency was set by the diamond microcavity and stable harmonic mode locking was achieved when the laser cavity length was tuned so that the laser operated on the 117th harmonic of the fundamental cavity. When an etalon placed intracavity next to the gain sample, but not in thermal contact was used pulse groups were observed. These contained 300 fs pulses with a spacing of 5.9 ps. We conclude that to achieve stable harmonic mode locking at repetition frequencies in the 100s of GHz range in a VECSEL there is a threshold pulse energy above which harmonic mode locking is achieved and below which groups of pulses are observed

Guide to the meso-scale production of the copepod Acartia tonsa

This manual is intended as a guide for the daily production of a few million A. tonsa nauplii for feeding to marine vertebrates and invertebrates. This scale of production is greater than most research would require, but smaller than commercial production, hence the term meso-scale production. This manual will briefly describe the biology of Acartia tonsa Dana that is relevant to culture, the culture methodology for meso-scale production of their eggs and nauplii, the system components utilized in production, and how to construct a few simple tools useful for this scale of production. Commercial production of copepods requires much greater feed production than is described, or the development of an efficient artificial feed, and, therefore, is not the focus of this manual. (PDF conatains 29 pages.

Comparison of the mean photospheric magnetic field and the interplanetary magnetic field

Polarity comparison of solar magnetic field and interplanetary magnetic fiel

Techniques for Restoration of Disturbed Coastal Wetlands of the Great Lakes

A long history of human-induced degradation of Great Lakes wetlands has made restoration a necessity, but the practice of wetland restoration is relatively new, especially in large lake systems. Therefore, we compiled tested methods and developed additional potential methods based on scientific understanding of Great Lakes wetland ecosystems to provide an overview of approaches fur restoration. We addressed this challenge by focusing on four general fields of science: hydrology, sedimentology, chemistry, and biology. Hydrologic remediation methods include restoring hydrologic connections between diked and hydrologically altered wetlands and the lakes, restoring water tables lowered by ditching, and restoring natural variation in lake levels of regulated lakes Superior and Ontario. Sedimentological remediation methods include management of sediment input from uplands, removal or proper management of dams on tributary rivers. and restoration of protective barrier beaches and sand spits. Chemical remediation methods include reducing or eliminating inputs of contaminants from point and non-point sources, natural sediment remediation by biodegradation and chemical degradation, and active sediment remediation by removal or by in situ treatment. Biological remediation methods include control of non-target organisms, enhancing populations of target organisms, and enhancing habitat for target organisms. Some of these methods were used in three major restoration projects (Metzger Marsh on Lake Erie and Cootes Paradise and Oshawa Second Marsh on Lake Ontario). which are described as case studies to show practical applications of wetland restoration in the Great Lakes. Successful restoration techniques that do not require continued manipulation must be founded in the basic tenets of ecology and should mimic natural processes. Success is demonstrated by the sustainability, productivity, nutrient-retention ability, invasibility, and biotic interactions within a restored wetland

Steady-state creep of dispersion-strengthened metals Final report

High temperature creep behavior of recrystallized nickel-thorium oxide alloys studied with vacuum constant-stress creep condition