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91.
92.
R. Bindlish T.J. Jackson B. Stankov M.H. Cosh C. Watts V. Lakshmi T. Keefer 《Remote sensing of environment》2008,112(2):375-390
An unresolved issue in global soil moisture retrieval using passive microwave sensors is the spatial integration of heterogeneous landscape features to the nominal 50 km footprint observed by most low frequency satellite systems. One of the objectives of the Soil Moisture Experiments 2004 (SMEX04) was to address some aspects of this problem, specifically variability introduced by vegetation, topography and convective precipitation. Other goals included supporting the development of soil moisture data sets that would contribute to understanding the role of the land surface in the concurrent North American Monsoon System. SMEX04 was conducted over two regions: Arizona — semi-arid climate with sparse vegetation and moderate topography, and Sonora (Mexico) — moderate vegetation with strong topographic gradients. The Polarimetric Scanning Radiometer (PSR/CX) was flown on a Naval Research Lab P-3B aircraft as part of SMEX04 (10 dates of coverage over Arizona and 11 over Sonora). Radio Frequency Interference (RFI) was observed in both PSR and satellite-based (AMSR-E) observations at 6.92 GHz over Arizona, but no detectable RFI was observed over the Sonora domain. The PSR estimated soil moisture was in agreement with the ground-based estimates of soil moisture over both domains. The estimated error over the Sonora domain (SEE = 0.021 cm3/cm3) was higher than over the Arizona domain (SEE = 0.014 cm3/cm3). These results show the possibility of estimating soil moisture in areas of moderate and heterogeneous vegetation and high topographic variability. 相似文献
93.
本探讨了将微波这一新技术应用在钛铁矿冶金的可行性.结果表明,钛铁矿精矿经“微波辐矿经”微波辐照——盐酸浸出法”能制得供硫酸法生产钛白的酸溶性富钛渣,且具有方法新、能耗低、工艺简便等特点. 相似文献
94.
The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, the test data in requirement of traditional impedance method are "just enough" and not "redundant" to comprehensively evaluate the electromagnetic properties of materials. A novel optimization approach involving multiple impedance measurements is introduced in this paper to implement automatic measurement for electromagnetic parameters on microwave slot-line. Some results for standard samples and microwave absorbing materials are given. 相似文献
95.
Yeon-Tae YuAuthor Vitae Prabir DuttaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):444-449
Au/SnO2 core-shell structure nanoparticles (NPs) were synthesized using two methods, microwave and conventional precipitation. In both cases, the size of the Au core was 12-18 nm and the thickness of the SnO2 shell was 8-12 nm. The particle size of SnO2 synthesized using the microwave and precipitation method was 3-5 nm and 1-2 nm, respectively. Upon heating to 400-600 °C, both particles maintained their core-shell morphology but the smaller SnO2 particles prepared using the precipitation method were more sintered. The resistance changes in films of these particles were measured as a function of CO concentration. The Au/SnO2 particles prepared using the microwave method showed higher sensor response than those prepared using the precipitation method, even providing a significant signal at testing temperatures approaching ambient conditions, thereby affording a new class of material for gas sensing. Both sets of core-shell particles showed higher sensor response than the SnO2 nanoparticles. The role of the Au core as a catalyst in improving the adsorption and oxidation of CO gas is important for improving the low temperature response. In addition, the maintenance of the size of SnO2 in the microwave method during sintering contributed to the higher response towards CO sensing. 相似文献
96.
Investigation on formaldehyde gas sensor with ZnO thick film prepared through microwave heating method 总被引:1,自引:0,他引:1
ZnO nanopowders were prepared through microwave heating method. ZnO thick film sensors were fabricated by using ZnO nanopowders as sensing materials. The phase composition and morphology of the material particles were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The gas-sensing properties of the sensors based on ZnO nano-materials were investigated. It was found that the sensor based on ZnO nano-materials (low power, 10× 10 min) exhibited very high responses to benzene and toluene when operating at 440 and 370 °C, respectively; but the sensor based on ZnO (low power, 10× 10 min) showed very low responses to benzene and toluene when operating at 205–215 °C. The sensor based on ZnO (low power, 10× 10 min) showed high response and good selectivity to dilute formaldehyde when operating at 210 °C; especially, the response to 0.001 ppm HCHO attained 7.4 when operating at 210 °C. 相似文献
97.
During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. The opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological variables above the canopy. In addition, xylem sapflow of trees was measured within the flux tower footprint. We observed considerable diurnal differences between measured canopy opacities and modeled theoretical opacities that were closely linked to xylem sapflow. It is speculated that dielectric changes in the leaves induced by the sapflow are causing the observed diurnal changes. In addition, canopy intercepted rain and dew formation also modulated the diurnal opacity cycle. With an enhanced canopy opacity model accounting for water deposited on the leaves, we quantified the influence of canopy stored water (i.e. intercepted water and dew) on the opacity. A time series of dew formation and rain interception was directly monitored during a period of two weeks. We found that during light rainfall up to 60% of the rain amount is intercepted by the canopy whereas during periods of intense rainfall only 4% were intercepted. On average, 0.17 mm of dew was formed during the night. Dew evaporation contributed 5% to the total water vapor flux measured above the canopy. 相似文献
98.
Homogeneous and nano-sized BPNT [(Ba1-xPbx)Nd2Ti5O14] powders were prepared under various hydrothermal conditions. Crystallinity and homogeneity of the synthetic powders were
investigated. The microwave dielectric properties of the filters prepared with hydrothermal powders were compared with those
of the filters prepared with conventional powders. The microwave dielectric properties of the filter prepared with the hydrothermal
powders were also better than those of the filter manufactured with the conventional powders. The dielectric constant, quality
constant and temperature coefficient of resonance frequency of hydrothermally prepared filter under optimum condition and
measured at 3.5 GHz around were about 93, 6067 and 0 ppm/°C, respectively. 相似文献
99.
100.
针对某钢铁企业烧结厂烧结生产原料供应调度问题,提出了面向MES的烧结生产原料供应调度系统的整体功能、结构和设计原则,并采用了模型加启发式算法和人际交互相结合的烧结生产原料供应调度计划编制方法。设计并开发了烧结生产原料供应调度系统,通过现场数据离线仿真表明:该系统可快速准确地编制出符合现场情况、满足工艺要求、高效的烧结生产原料供应调度计划。 相似文献