Results 231 to 240 of about 2,736,764 (275)
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An Annual Ring Antenna for UWB Communications
IEEE Antennas and Wireless Propagation Letters, 2006An ultrawideband (UWB) annual ring antenna is presented in this letter. The annual ring antenna has a return loss better than 10 dB from 2.8 to 12.3 GHz. It has an average gain of 2.93 dBi and has a maximum gain of 5 dBi at 7 GHz. The antenna radiation patterns are stable within its operation band.
Y -J Ren
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Climatic response of annual tree-rings
SPIE Proceedings, 2014Extensive literature devoted to investigations into the influence of environmental conditions on the plant respiration and respiration rate. It is generally accepted that the respired CO2 generated in a stem completely diffuses into the atmosphere. Results obtained from explorations into the CO2 content in disc tree rings by the method proposed in this
Boris G. Ageev +3 more
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Distribution and Speciation of Metals in Annual Rings of Black Willow
Journal of Environmental Quality, 2005ABSTRACTInformation on the spatial distribution and speciation of metals in nonhyperaccumulator plants is lacking. This study used synchrotron X‐ray fluorescence (SXRF) compositional imaging to investigate the spatial distribution of Ni, Mn, Cu, Zn, and Fe in annual rings of black willow (Salix nigra L.) collected from a metal‐contaminated area, and ...
Tracy, Punshon +4 more
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Enhancement of annual rings on industrial CT images of logs
Object recognition supported by user interaction for service robots, 2003Many researchers have shown the ability of X-ray computer tomography (CT) of acquiring knowledge about the internal structure of logs. Contrarily to medical CT scanners, industrial CT scanners should satisfy more extreme constraints (in terms of speed, duty cycle, radiation safety, reconstruction circle and aperture size) in order to be used in a ...
Jean-Philippe Andreu, Alfred Rinnhofer
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Annual Bird Ringing Totals and Population Fluctuations
Oikos, 1978Ringing of migrant birds has taken place at Ottenby, Oland, southeast Sweden since 1947. The effect of the winter weather in northwestern Europe on the wren Troglodytes troglodytes, of precipitation in the Sahel zone on the common whitethroat Sylvia communis and of the use of alkyl mercury compounds in Swedish agriculture on the yellowhammer Emberiza ...
Christian Hjort +2 more
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Annual Growth Rings in a Sample of Hymenaea Courbaril
IAWA Journal, 2006Several tropical tree species form regular growth rings that may be annual and thus be useful in paleoclimate reconstructions. Regular growth rings were observed in one stem disk of the tropical legume Hymenaea courbaril harvested near the city of David, Panama. By comparison to annual reference Δ14C values from temperate tree wood and air, Δ14C values
Jessica A. Westbrook +2 more
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ANNUAL RINGS IN HEMLOCKS AND THEIR RELATION TO ENVIRONMENTAL FACTORS
American Journal of Botany, 1940THE HURRICANE of September 21, 1938, uprooted a grove of hemlocks, Tsuga canadensis (L.) Carr., in the Connecticut Arboretum at Connecticut College, thus providing material for a study of their annual growth rings. There were originally 130 trees in the grove, oily 18 of which remained standing after the storm.
G. S. Avery, H. B. Creighton, C. W. Hock
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Molt in the Annual Cycle of Ring-Necked Ducks
The Condor, 1995Birds have increased energy and nutrient requirements during molt. Estimation of these costs has proven difficult; consequently, the nutritional significance of molt relative to other annual cycle events remains unclear. Here we describe patterns of molt for Ring-necked Ducks (Aythya collaris) throughout their annual cycle.
Hohman, William L., Crawford, Richard D.
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Stiffening phenomena in annual rings of coniferous wood
Wood Science and Technology, 1984The structure of coniferous wood is characterized by pronounced differences in density between earlywood and latewood. This could result in disadvantages in wood strength especially against bending. A summary of the observations in this paper leads to the following hypothesis: Coniferous trees meet this danger by forming numerous stiffenings especially
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Radiocarbon Measurements and Annual Rings in Cave Formations
Nature, 1960THE radiocarbon method has been used to test the hypothesis that the prominent rings found in certain calcite deposits of Moaning Cave in California represent annual growth variations. Carbon-14 an alyses were made on two samples taken, from a presumably active section of travertine covering a human femur (Fig. 1). When discovered in 1951, the specimen
WALLACE S. BROECKER +2 more
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