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排序方式: 共有685条查询结果,搜索用时 15 毫秒
1.
CAROL A. WESSMAN JOHN D. ABER DAVID L. PETERSON 《International journal of remote sensing》2013,34(8):1293-1316
Abstract High spectral resolution Airborne Imaging Spectrometer (AIS) data were acquired over 20 well-studied Wisconsin forest sites to evaluate the potential of remote sensing for estimating forest canopy chemistry. Intensive nutrient cycling research in these forests demonstrates that canopy lignin content is strongly related to measured annual nitrogen mineralization at the undisturbed sites and may serve as an accurate index for nitrogen cycling rates. Ground measurements were made of foliar biomass and canopy nitrogen and lignin content, the latter within two weeks of the AIS overflight. The spectral data were transformed using derivative techniques modified from laboratory spectroscopy. Stepwise regression assisted in determining combinations of wavelengths most highly correlated with canopy chemistry and biomass. Strong correlations between AIS data and total canopy lignin content in deciduous forests and canopy lignin concentration (total lignin/biomass) in both deciduous and coniferous stands indicate that imaging spectrometry can be used to estimate canopy lignin content and, from that, the spatial distribution of annual nitrogen mineralization rates. 相似文献
2.
DAVID SHERES DAVIDSON T. CHEN G A SPAR R. VALENZUELA 《International journal of remote sensing》2013,34(11):1629-1640
Abstract First, a general review is presented of wave-current interaction processes ( for horizontal shears) and their effect on radar backscatter and radar imagery ( SAR/ RAR ) Then numerical results on the refraction of wave energy trajectories by complex bottom topography (finite depth) and a linear shear current are presented. For deep water, the wave-energy trajectories are given for mesoscale currents ( e.g. eddies and double-vortex configurations). The focusing of wave energy by variable currents found here should have important influence on the spatial scale of wind stress over the ocean, and on optical and acoustic properties of the upper layer of the ocean. 相似文献
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DAVID G. MEYER 《International journal of control》2013,86(4):1227-1234
It is shown that on the set of w-input, p-output asymptotically stable, minimal, nth order systems that the H∞ p·m and the RN quoiient induced topologies coincide. Implications of this in frequency domain system identification are discussed 相似文献
5.
PARKER C. REIST DAVID F. UTTERBACK HARRY BARR 《Particulate Science and Technology》2013,31(4):315-323
ABSTRACT A pulsed jet pleated paper cartridge filter system was tested for particle removal efficiency and operating stability using agricultural limestone as the test dust. The test system consisted of 6 pleated paper filter units arranged in parallel, each unit having an effective filtration area of 18.1 square meters. The system was operated at constant pressure drops of 6.25, 7.50 and 8.75 kPa (2.5, 3.0 and 3.5 inches of water), with face velocities of 0.78 to 1.04 m/ min (2.5 to 3.4 feet per minute) and dust loadings ranging from 0.5 g/ m to 2.5 g/ m3. Penetration through the media appeared to be relatively independent of dust loading, and efficiencies were in the 99.95 + % range. Slightly lower efficiencies were found for particles having diameters of 0.3 to 1.0 micrometers. A measure of the redeposition of dust pulsed from the filter was required to describe the effects on the pulse rate caused by changes in system flow and pulsing set point. Increased redeposition was found to occur with increasing flow rate, causing an increase in the pulse rate required to maintain operation of the system at a pulsing set point. Overall, the reverse pulse jet pleated paper cartridge filter system displayed extremely high particle removal efficiency in a compact unit that operated with low differential pressure. 相似文献
6.
The Total Source Error of Adjustment (TSEA) model identifies and describes the sources of error that create the need for setup and process adjustment. Adjustment is the result of uncontrolled sources of variation or error. To control error, it must first be systematically identified and described. The TSEA model is a systematic means of identifying and classifying the error sources contributing to setup adjustment and process adjustment for machining processes. Once error sources are properly classified, touch-trigger probing can then be effectively used to eliminate variability. When implementing the TSEA model, probing is applied to control error sources of adjustment. A case study examines the utility of the TSEA methodology in identifying the sources of variation causing adjustment. The analysis and control of error sources that occur in machining will reduce setup time, increase consistency in manufacturing, and improve the quality of the final product. 相似文献
7.
DAVID M. GATES 《International journal of remote sensing》2013,34(7):1095-1107
Abstract The global climate has warmed by over 0·5°C during the last 125 years. Models of the Earth's temperature reponse to increasing levels of atmospheric carbon dioxide and other greenhouse gases estimate that the average global surface temperature will rise about 4°C by the mid twenty-first century. High latitudes will warm more than lower latitudes and winters more than summers. Forests will undergo enormous changes as temperatures increase and precipitation patterns shift. It is doubtful that forest movement will meet the rate of climate change. Many sensitive hardwood tree species, such as paper and yellow birch, sugar maple and black ash, may die. Boreal forests will replace tundra and mixed hardwood forests will replace them. Much of the change expected in the location and composition of forests may be detected by means of remote sensing. 相似文献
8.
This study deals with the Automated Guided Vehicle System guide path design problem. We suggest a single closed loop guide path layout configuration as an alternative to conventional but more complex guide path designs. The benefits of using a simple guide path versus more complicated guide paths are discussed. A procedure for designing an optimal single loop guide path for a given facility layout is presented. Finally, the single loop's throughput performance is tested and compared to that of a more complex guide path. 相似文献
9.
We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground state, for atoms that are initially prepared in the excited state. This provides the POM elements, which describe such sequences of measurements. 相似文献
10.
A hybrid (symbolic-numeric) system, referred to as OPTDEX, (OPTIMAL DESIGN EXPERT) for the optimal design or mechanical components and systems has been developed. The system is written in Golden Common LISP and IBM Professional (Ryan-McFarland) FORTRAN for execution on the IBM PC/AT microcomputer. Graphical output has been implemented using the Graphical Kernel System (GKS) standard. This microcomputer-based implementation makes the system particularly attractive as an easily accessible, low cost engineering analysis and design tool. Experience with the system indicates that the time required to achieve, at least, partially optimized engineering design solutions is similar to that which may be expected with standard, nonoptimization-based, microcomputer computation. Any added computational time may be justified and subsequently offset by increased long term design efficacy. 相似文献