2,881 research outputs found
Engineering transport by concatenated maps
We present a generalized kick rotor model in which the phase of the kick can
vary from kick to kick. This additional freedom allows one to control the
transport in phase space. For a specific choice of kick-to-kick phases, we
predict novel forms of accelerator modes which are potentially of high
relevance for future experimental studies
Geophysical and Biological Reconnaissance of Rock Habitats in Western Camden Bay, Beaufort Sea, Alaska
This report presents the results of a 10-day geophysical and
biological survey in western Camden Bay, in the Alaskan Beaufort Sea.
The primary objective of this survey was to confirm the existence of
boulders and cobbles on the seafloor as reported by Barnes (1981, 1982).
The survey area extended from the eastern edge of the Canning River (mud
flat area) to Kangigivik Point and seaward to the 14m contour line
(Fig. 1). A solid boundary of pack ice prevented any survey work
seaward of the 14m contour. We had proposed to examine the seabed to
the 18m contour.This work was
supported by the Bureau of Land Management through an interagency
agreement with the National Oceanic and Atmospheric Administration,
under which a multiyear program responding to needs of petroleum
development of the Alaskan Continental Shelf is managed by the Outer
Continental Shelf Environmental Assessment Program (OCSEAP) office
V-band IMPATT power amplifier
This program is the result of the continuing demand and future requirement for a high data rate 60-GHz communications link. A reliable solid-state transmitter which delivers the necessary power over a wide bandwidth using the present IMPATT diode technology required the development of combining techniques. The development of a 60-GHz IMPATT power combiner amplifier is detailed. The results form a basis from which future wideband, high-power IMPATT amplifiers may be developed. As a result, several state-of-the-art advancements in millimeter-wave components technology were achieved. Specific achievements for the amplifier integration were: development of a nonresonant divider/combiner circuit; reproducible multiple junction circulator assemblies; and reliable high power 60-GHz IMPATT diodes. The various design approaches and tradeoffs which lead to the final amplifier configuration are discussed. A detailed circuit design is presented for the various amplifier components, and the conical line combiner, radial line combiner, and circulator development are discussed. The performance of the amplifier, the overall achievement of the program, the implications of the results, and an assessment of future development needs and recommendations are examined
Development and application of operational techniques for the inventory and monitoring of resources and uses for the Texas coastal zone. Volume 1: Text
The author has identified the following significant results. Image interpretation and computer-assisted techniques were developed to analyze LANDSAT scenes in support of resource inventory and monitoring requirements for the Texas coastal region. Land cover and land use maps, at a scale of 1:125,000 for the image interpretation product and 1:24,000 for the computer-assisted product, were generated covering four Texas coastal test sites. Classification schemes which parallel national systems were developed for each procedure, including 23 classes for image interpretation technique and 13 classes for the computer-assisted technique. Results indicate that LANDSAT-derived land cover and land use maps can be successfully applied to a variety of planning and management activities on the Texas coast. Computer-derived land/water maps can be used with tide gage data to assess shoreline boundaries for management purposes
Development and application of operational techniques for the inventory and monitoring of resources and uses for the Texas coastal zone. Volume 2: Appendices
There are no author-identified significant results in this report
Teacher-Set Pre-Reading Purposes and Comprehension
Because some basal reader teachers\u27 guides recommend written pre-reading purposes while others suggest only oral ones, the major purpose of this study was to compare the comprehension of stories in the basal reader using three pre-reading purpose treatments: (1) written, (2) oral, and (3) no purpose (control)
Teacher-Set Pre-Reading Purposes and Comprehension
Because some basal reader teachers\u27 guides recommend written pre-reading purposes while others suggest only oral ones, the major purpose of this study was to compare the comprehension of stories in the basal reader using three pre-reading purpose treatments: (1) written, (2) oral, and (3) no purpose (control)
Position-dependent shear-induced austenite-martensite transformation in double-notched TRIP and dual-phase steel samples
While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation behaviour in an inhomogeneous yet carefully controlled shear-loaded region of double-notched TRIP and dual-phase (DP) steel samples. A detailed powder analysis has been performed to simultaneously monitor the evolution of the phase fraction and the changes in average carbon concentration of metastable austenite together with the local strain components in the constituent phases as a function of the macroscopic stress and location with respect to the shear band. The metastable retained austenite shows a mechanically induced martensitic transformation in the localized shear zone, which is accompanied by an increase in average carbon concentration of the remaining austenite due to a preferred transformation of the austenite grains with the lowest carbon concentration. At the later deformation stages the geometry of the shear test samples results in the development of an additional tensile component. The experimental strain field within the probed sample area is in good agreement with finite element calculations. The strain development observed in the low-alloyed TRIP steel with metastable austenite is compared with that of steels with the same chemical composition containing either no austenite (a DP grade) or stable retained austenite (a TRIP grade produced at a long bainitic holding time). The transformation of metastable austenite under shear is a complex interplay between the local microstructure and the evolving strain fields
Development and application of operational techniques for the inventory and monitoring of resources and uses for the Texas coastal zone
The author has identified the following significant results. Four LANDSAT scenes were analyzed for the Harbor Island area test sites to produce land cover and land use maps using both image interpretation and computer-assisted techniques. When evaluated against aerial photography, the mean accuracy for three scenes was 84% for the image interpretation product and 62% for the computer-assisted classification maps. Analysis of the fourth scene was not completed using the image interpretation technique, because of poor quality, false color composite, but was available from the computer technique. Preliminary results indicate that these LANDSAT products can be applied to a variety of planning and management activities in the Texas coastal zone
Swelling strains from gamma-irradiated silica - Evaluation of results by Shelby
Water introduced in silica reacts with the silica network under hydroxyl generation that causes a volume swelling. This effect has been discussed quantitatively in much detail in [1] for the case of water entrance by a heat treatment procedure. In the present Report we include also data by Shelby [8] obtained by in-situ generation of hydroxyl in gamma-irradiated silica. This procedure resulted in stronger density changes compared with the heat-treated material. Independent of this fact, we can show that the same volume swelling results for both methods. As an application of the results an estimation of the molar volume of hydroxyl is made
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