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151.
俞丽婷 《湖南环境生物职业技术学院学报》2006,12(1):114-116
家用综合防盗系统从实际防护入手,根据门、窗(阳台)所处位置特点,独立防护,防护系统与控制系统用无线联系,便于隐蔽、安装灵活,根据防护实际需要可随意增、减独立防护装置;采用交直流电源转换电路,增强了抗破坏能力,是工薪族家庭防非法侵入的理想防护装置.本系统由雷达扫描、护窗口(阳台)无线电发射电路、微振动护门无线电发射电路、无线电接收中央控制、功放报警电路等五部分组成. 相似文献
152.
关于酸性粒子大小计算的研究 总被引:4,自引:0,他引:4
酸性粒子在许多环境问题中起着重要的作用.它们的大小一直用Gras公式计算.但在实际的研究中发现Gras公式有时并不合理.提出对Gras公式进行改进以粒子投影长度L与截面积直径d的比例关系,L/d<0.62用Gras公式计算,0.62~1.62用修正的Gras公式计算,>1.62须具体对待.并用具体算例证实了新算法的合理性. 相似文献
153.
Cross-borehole ground penetrating radar (XBGPR) is used in monitoring a long-term vadose zone infiltration experiment at a test site in Socorro, NM in order to examine contaminant transport in the vadose zone. XBGPR attenuation tomography is conducted in order to test the ability of using images of electromagnetic attenuation for hydrogeologic investigations. The results of four pre-infiltration attenuation inversions shows standard deviations below 0.1 Np/m, and demonstrate the consistency of the XBGPR tomography technique for making time-lapse observations. Correlation to the core records indicates that XBGPR attenuation tomograms provide high-resolution images of clay distribution in the vadose zone. Water infiltration at the ground surface was initiated in February 1999 at a constant rate of 2.7 cm/day, and continued at this rate throughout the data collection experiment. Time-lapse attenuation tomograms show that attenuation increases by approximately 0.3 Np/m during the water infiltration, and indicate a snowplow effect may be occurring where salts are dissolved by the water and concentrated at the front of the plume. Seasonal temperature changes may also cause changes in electromagnetic attenuation images, and masking the evidence of water infiltration. Thus caution must be taken when using time-lapse attenuation images to interpret the movement of a water plume during a long-term experiment as temperature changes. 相似文献
154.
The spatial resolution of satellite imagery suitable for earth resources studies has improved from 80 m (Landsat-MSS, launched in 1972) to 0.6 m (QuickBird, launched in 2001). The conventional pixel-based methods developed for medium resolution satellite images are not suitable for classification of very high spatial resolution images, because the spectral responses of particular habitat classes are much more variable. On the other hand, in the original Barnsley–Barr kernel-based reclassification algorithm not only the spectral information of a pixel but also the textural information in the vicinity of the pixel is used when the pixel labeling decision is made. The first step of the kernel reclassification algorithm is to perform an initial classification of the original image. In the second step, the adjacency-event matrices are computed for each pixel according to co-occurrence frequencies of the initial classes in the kernel window. The degree of matching between an adjacency-event matrix corresponding to specific pixel and the set of class-specific template matrices produced during training is the criterion for pixel re-labeling. We extend the original kernel-based reclassification algorithm with a decision tree-based reclassification, simultaneously taking into account the class-specific similarity images, which are a side-product of the original algorithm. The advantage of decision tree-extended approach over the original approach seems to be the ability of the former to consider more input information, thus increasing the Kappa classification accuracy for an Ikonos image of our study area from 0.56 to 0.60, using a nomenclature containing 10 habitat classes. 相似文献
155.
Steven D. Warren Victor E. Diersing Pamela J. Thompson William D. Goran 《Environmental management》1989,13(2):251-257
The universal soil loss equation (USLE) has been integrated with a geographic information system known as the geographical resources analysis support system (GRASS) to create a land classification system for use by military trainers and land managers to minimize the environmental impacts of military training activities. The USLE provides an estimate of current average annual sheet and rill erosion based upon factors representing climate, soil erodibility, topography, cover, and conservation support practices. The erosion estimate is compared to erosion tolerance values to produce an expression of the current erosion status. An index of inherent site erodibility is also achieved through manipulation of the USLE. Based on published soil surveys, satellite imagery, and ground-truth vegetation transects, data layers are created within GRASS for each of the component factors of the USLE. Appropriate mathematical operations are performed with the data layers, and color-coded maps are produced that represent the erosion status and erodibility index for each 50-m × 50-m area of soil surface. These maps aid military trainers and land managers in scheduling appropriate kinds and intensities of military training activities. 相似文献
156.
Raymond H. G. Klaassen Roine Strandberg Mikael Hake Thomas Alerstam 《Behavioral ecology and sociobiology》2008,62(9):1427-1432
We used novel Global Positioning System-based satellite telemetry to reconstruct daily time budgets on travelling days of
a long-distance migrant, the Osprey Pandion haliaetus, to reveal how landscape affects migratory performance. We compared daily travel routines between the Ospreys’ passage of
Europe and the Sahara. In Europe, where feeding habitat is abundant, Ospreys fed both before–after flights and during interruptions,
thus, combining migration with foraging. This resulted in a 2.7-h shorter daily flight period in Europe than in the Sahara.
A calculated energy budget indicated that a ‘fly-and-forage migration strategy’ is favourable in Europe because associated
benefits (energy intake) more than outweigh costs (reduced flight time). The much shorter flight time in Europe was the main
explanation why Ospreys covered on average 78 km less distance on a travelling day in Europe than in the Sahara. In addition,
there were regional differences in hourly flight speeds that are most probably the result of variation in thermal soaring
conditions. We conclude that landscape properties have a profound effect on migration through regional variation in daily
routines. 相似文献
157.
结合VLF/LF全闪定位系统、多普勒天气雷达、探空资料,对2013年7月5日江苏地区一次典型飑线过程的全闪活动特征进行了详细分析。结果表明:云地闪比的下降、上升预示着飑线过程中雷暴的加强、减弱;云闪主要分布在4~8 km高度,云闪频数最大值出现在5 km处;结合云闪变化情况和探空资料推测雷暴云内电荷为三极性电荷结构;对流区的闪电密度远大于层状云区。相比于正地闪,负地闪集中在雷达回波的强对流区。云闪发生位置更具随机性,易发生在弱回波区和层状云区;闪电的发生与云顶高度有很高的相关性,云闪发生位置与剖面反射率因子中强回波区的发展有很好的一致性。 相似文献
158.
珠江三角洲大暴雨的多普勒特征及形成机制 总被引:2,自引:0,他引:2
利用广州CINRAD-SA新一代多普勒天气雷达资料,结合天气形势分析,研究了华南地区夏季短时大暴雨的发生、发展过程,特别是中小尺度系统引发短时大暴雨不同发展阶段的多普勒特征以及辐合强度与短时大暴雨的关系,并对短时大暴雨的发展机制进行了初步探讨.通过分析发现,短时大暴雨产生于低空强盛西南气流等有利条件下,近地层雨区附近的气旋式扰动有利于激发对流,抽吸作用、局地锋生对对流的维持和加强起到了十分重要的作用.在短时大暴雨发生初期及发展旺盛期,大多数都伴有逆风区、辐合带等多普勒特征,中气旋更是与高强度降水、地面强风等剧烈天气密切相关. 相似文献
159.
A new method for multi-objective optimization of air quality monitoring systems based on satellite remote sensing of the troposphere
is described in this work. The technique uses atmospheric turbidity as surrogate for air pollution loading. Through inverse
chemical modeling and ancillary information the respective patterns of primary gaseous and particle pollutants are inferred.
The optimization algorithm uses the resulting maps of ambient air pollution as input. It focuses on the gain of information
with regard to human exposure to high pollution, potential impact on cultural heritage, compliance to ambient air quality
standards, monitoring key point and area source emissions, as well as on the associated cost. Application of the method in
Brescia, Italy showed its significant potential for improving the cost-effectiveness of air quality monitoring networks at
the urban and regional scales. 相似文献
160.
为加强对秸秆焚烧的管理,通过对国家环境保护总局公布的夏冬收获季节卫星遥感探测的火点情况的统计分析,2004年-2009年夏冬收获季节南通市空气质量日变化趋势分析及典型秸秆焚烧日环境空气中污染物的小时变化趋势分析,得出秸秆焚烧对南通市环境空气质量影响的程度,掌握了南通市秸秆焚烧地域分布情况. 相似文献