90,528 research outputs found
Carbon dioxide concentrator
Passed exhaled air through electrochemical cell containing alkali metal carbonate aqueous solution, and utilizes platinized electrodes causing reaction of oxygen at cathode with water in electrolyte, producing hydroxyl ions which react with carbon dioxide to form carbonate ions
Forest land management by satellite: LANDSAT-derived information as input to a forest inventory system
The author has identified the following significant results. Analysis of LANDSAT temporal data, specifically the digitally merged winter and summer scenes, provided the best overall classification results. Comparison of temporal classification results with available ground truth reveal a 94% agreement in the delineation of hardwood categories, a 96% agreement for the combined pine category, and a greater than 50% agreement for each individual pine subcategory. For nearly 1000 acres, compared clearcut acreage estimated with LANDSAT digital data differed from company inventory records by only 3%. Through analysis of summer data, pine stands were successfully classified into subcategories based upon the extent of crown closure. Maximum spectral separability of hardwood and pine stands was obtained from the analysis of winter data
Effect of thermal expansion on the linear stability of planar premixed flames for a simple chain-branching model: The high activation energy asymptotic limit
The linear stability of freely propagating, adiabatic, planar premixed
ames is investigated in the context of a simple chain-branching
chemistry model consisting of a chain-branching reaction step and a completion reaction step. The role of chain-branching is governed
by a crossover temperature. Hydrodynamic effects, induced by thermal expansion, are taken into account and the results compared and
contrasted with those from a previous purely thermal-di�usive constant density linear stability study. It is shown that when thermal
expansion is properly accounted for, a region of stable
ames predicted by the constant density model disappears, and instead the
ame
is unstable to a long-wavelength cellular instability. For a pulsating mode, however, thermal expansion is shown to have only a weak
e�ect on the critical fuel Lewis number required for instability. These e�ects of thermal expansion on the two-step chain-branching
ame
are shown to be qualitatively similar to those on the standard one-step reaction model. Indeed, as found by constant density studies, in
the limit that the chain-branching crossover temperature tends to the adiabatic
ame temperature, the two-step model can be described
to leading order by the one-step model with a suitably de�ned e�ective activation energy
Diagnosis: Reasoning from first principles and experiential knowledge
Completeness, efficiency and autonomy are requirements for suture diagnostic reasoning systems. Methods for automating diagnostic reasoning systems include diagnosis from first principles (i.e., reasoning from a thorough description of structure and behavior) and diagnosis from experiential knowledge (i.e., reasoning from a set of examples obtained from experts). However, implementation of either as a single reasoning method fails to meet these requirements. The approach of combining reasoning from first principles and reasoning from experiential knowledge does address the requirements discussed above and can possibly ease some of the difficulties associated with knowledge acquisition by allowing developers to systematically enumerate a portion of the knowledge necessary to build the diagnosis program. The ability to enumerate knowledge systematically facilitates defining the program's scope, completeness, and competence and assists in bounding, controlling, and guiding the knowledge acquisition process
Report on the EU-US Workshop on Large Scientific Databases
This joint workshop was set up under the auspices of the Joint European Commission/National Science Foundation Strategy Group that met in Budapest in September 1998. The meeting derived from a joint collaboration agreement between the EC and NSF, signed by Dr. George Metakides (Director of Information Technologies for the EC) and Prof. Juris Hartmanis (Director of Computer and Information Science and Engineering at the NSF). Some themes that were identified include:
digital libraries
human-centered computing and virtual environments
large scientific databases, and
intelligent implants
This report expresses the conclusions and recommendations of the Workshop on Large Scientific Databases, held in Annapolis, Maryland, USA in September 1999. The purpose of the workshop was to develop a report to the funding agencies outlining a possible solicitation to the research community, with emphasis on joint European-US work on Large Scientific Databases. Before the workshop, each participant submitted a position paper (these are available at the web site http://www.cacr.caltech.edu/euus). The results of the position papers, presentations, and group discussion are summarized in this report. There were 12 participants from Europe and 12 from the United States, and they are listed at the end of this report. The last section of this report describes possible funding mechanisms
The aspherical Cavicchioli-Hegenbarth-Repovš generalized Fibonacci groups
The Cavicchioli–Hegenbarth–Repovš generalized Fibonacci groups are defined by the presentations Gn (m, k) = 〈x 1, … , xn | xixi+m = xi+k (1 ⩽ i ⩽ n)〉. These cyclically presented groups generalize Conway's Fibonacci groups and the Sieradski groups. Building on a theorem of Bardakov and Vesnin we classify the aspherical presentations Gn (m, k). We determine when Gn (m, k) has infinite abelianization and provide sufficient conditions for Gn (m, k) to be perfect. We conjecture that these are also necessary conditions. Combined with our asphericity theorem, a proof of this conjecture would imply a classification of the finite Cavicchioli–Hegenbarth–Repovš groups
Beware the Non-uniqueness of Einstein Rings
We explain how an approximation to the rings formed by the host galaxies in
lensed QSOs can be inferred from the QSO data alone. A simple ring image can be
made from any lens model by a simple piece of computer graphics: just plot a
contour map of the arrival-time surface with closely-spaced contours. We go on
to explain that rings should be (a) sensitive to time-delay ratios between
different pairs of images, but (b) very insensitive to H_0. We illustrate this
for the well-known quads 1115+080 and 1608+656.Comment: To appear in AJ (circa Aug 2001
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