共查询到20条相似文献，搜索用时 46 毫秒
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探讨了太阳能、振动能和气流能等3种潜在的环境能量及其利用方法。这些方法可有效解决传感器网络节点需要足够持续的能量而传统的电池供能方式不能满足的实际问题。 相似文献
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去噪小波包能量法在水声信号识别中的应用 总被引：1，自引：0，他引：1
对小波包能量法进行改进，提出了一种新的方法——去噪小波包能量法，该算法对信号小波去噪后，再用小波包能量法提取信号的特征；应用去噪小波包能量法研究了不同的小波去噪方法对水声信号分类识别率的影响，在实测信号样本集上用BP神经网络进行了识别实验。结果显示软阈值、硬阈值、弹性阈值3种标准的小波去噪方法均能明显提高信号识别率，其中最为显著的是软阈值标准去噪，信号的识别率可由未去噪的53．3％提高到98．3％，表明算法的有效性。 相似文献
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去噪小波包能量法在水声信号识别中的应用 总被引：2，自引：0，他引：2
对小波包能量法进行改进,提出了一种新的方法———去噪小波包能量法,该算法对信号小波去噪后,再用小波包能量法提取信号的特征;应用去噪小波包能量法研究了不同的小波去噪方法对水声信号分类识别率的影响,在实测信号样本集上用BP神经网络进行了识别实验。结果显示软阈值、硬阈值、弹性阈值3种标准的小波去噪方法均能明显提高信号识别率,其中最为显著的是软阈值标准去噪,信号的识别率可由未去噪的53 .3%提高到98. 3%,表明算法的有效性。 相似文献
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根据高应力区砂岩三轴压缩试验和峰前卸围压试验的结果,分析了砂岩在不同应力路径下的能量变化规律。试验结果表明,相同围压下,峰前卸围压试验的各能量指标(总吸收能、弹性应变能、耗散能)均小于三轴压缩试验,能量变化特征与其初始应力路径密切相关,且随围压的增大而增大。峰前储存的弹性应变能比耗散能多,耗散能只在临近峰值点处才迅速增加。能量的耗散会导致岩石产生损伤,并且使岩性劣化、丧失强度,从能量角度定义的损伤变量,可以得出结论:开始卸荷低围压下的损伤变量大于高围压下,临近破坏时高围压下的损伤变量大于低围压下;卸围压使岩样束缚减小,加速了损伤的发展,岩样所受的应力状态愈趋不平衡。因此,基于能量的角度来表征岩石的损伤演化更符合实际。 相似文献
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地核不仅具有巨量热能，而且有巨量旋转能，这是地球能量释放的内因；天文因素使地核产生周期性的南北振荡，是地球能量间歇性释放的外因。地质旋回与天文周期直接相关，可以根据天文周期预测未来的地质变化 相似文献
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钻孔应变台站记震能力研究 总被引：4，自引：0，他引：4
以昌平台体应变为例,研究了体现钻孔应变台站记震能力的方法,并对计算步骤和处理方法进行了说明.选取20套中国大陆观测时间较长且数据较好的钻孔体应变仪观测记录作为研究对象,计算出其各自的记震能力线,给出各台对6级地震的响应范围.此公式不仅可以量化钻孔应变仪的对地震的反应能力,而且是对地震仪器的一种新的科学评估方法.同时,基于地震前兆释放能量小于地震发生时释放的能量的基本理解,此结果对于确定地震前兆的位置和震级范围也有参考价值. 相似文献
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遥感地表能量信息能够反映城市生态系统成分、作用与影响关系。本研究从城市生态系统的角度,提取能反映城市下垫面地物实体综合特征、作用与影响关系的相对地表能量信息,针对不同区域、规模与类型城市的地表能量空间分布及特征,建立了定量化的城市相对地表能量分级与评价指标。探讨国际"宜居型城市"生态系统结构、功能、形态及其时空变化特征和规律。结果表明:(1)城市实体空间建筑群的形状、体量,街道与建筑的朝向和配置关系,以及硬质化表面开放性的差异影响城市地表能量的分布。(2)建筑物周边的植被覆盖程度、建筑物之间的空间关系、广场和街道的开放性等,是维持城市开敞空间与实体空间的混合区域地表能量平衡的基础。宜居城市中心周围的大规模低密度居住区构成以中等能量分布为主的城市地表能量缓冲与过渡区。(3)城市开敞空间的地表能量变化幅度比实体空间大,宜居城市开敞空间的中、低地表能量分布占有较高比例。(4)宜居城市实体空间的高能量斑块呈现规模较小和分布相对分散的状态。采用相对地表能量分级与评价指标,可为各类城市规划与设计提供科学依据。 相似文献
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遥感地表能量信息能够反映城市生态系统成分、作用与影响关系。本研究从城市生态系统的角度,提取能反映城市下垫面地物实体综合特征、作用与影响关系的相对地表能量信息,针对不同区域、规模与类型城市的地表能量空间分布及特征,建立了定量化的城市相对地表能量分级与评价指标。探讨国际“宜居型城市”生态系统结构、功能、形态及其时空变化特征和规律。结果表明：（1）城市实体空间建筑群的形状、体量,街道与建筑的朝向和配置关系,以及硬质化表面开放性的差异影响城市地表能量的分布。（2）建筑物周边的植被覆盖程度、建筑物之间的空间关系、广场和街道的开放性等,是维持城市开敞空间与实体空间的混合区域地表能量平衡的基础。宜居城市中心周围的大规模低密度居住区构成以中等能量分布为主的城市地表能量缓冲与过渡区。（3）城市开敞空间的地表能量变化幅度比实体空间大,宜居城市开敞空间的中、低地表能量分布占有较高比例。（4）宜居城市实体空间的高能量斑块呈现规模较小和分布相对分散的状态。采用相对地表能量分级与评价指标,可为各类城市规划与设计提供科学依据。 相似文献
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赵平 《成都信息工程学院学报》1990,(Z1)
本文用ρ坐标系中的线性化斜压方程组,在地转近似下应用WKB方法导出了超长波的频率方程和能量方程,并讨论了纬向气流对超长波能量垂直传播的影响。指出:超长波能量具有守恒性;在冬季,不同纬度,由于基本气流垂直分布不同。可使超长波能量上传或下传,并在某些高度聚集。 相似文献
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一种复杂背景下的人脸特征提取算法 总被引：1，自引：0，他引：1
通过人脸特征提取是计算机人脸识别技术中的核心技术。主动轮廓模型方法(Activecontourmodel,也称Snakes方法)被广泛应用于特征提取、图像分割等技术中。常规Snakes方法应用于人脸特征提取鲁棒性不强,并且精度不高。对常规Snakes方法进行了改进,其改进主要包括两个方面:1)针对人脸肤色的特点改造了Snakes能量函数的图像能量项,用以提高算法的精度;2)基于人脸五官形状特点,增加了一个新的能量项———形状限定能量项,以期获得更好的鲁棒性。最后,对改进前后的Snakes方法进行了实验仿真与比较、对比研究。实验结果表明,改进后的Snakes方法具有良好的收敛性,并能准确收敛到人脸特征处。 相似文献
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Based on the hydrographic data in austral summer during the 22nd Antarctic Expedition of China(2005/2006),some features can be found about the northern margin of Emery ice shelf as follows.The heat content in the surface layer(0-50 m) at the eastern end and the western end of the ice-shelf margin is much higher than that at the middle.The upper mixing-layer depth and the seasonal thermocline depth at the middle of the ice-shelf northern margin are much shallower than those at the both ends.However there is much less difference between the middle and the ends in the bottom layer.The remote sensing photos show that the inhomogeneity in the surface-layer water is closely related to the spatial distribution of the floes and polynia in the area. 相似文献
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Phylogenetic analysis based on 16S rDNA of 8 strains of cultivable bacteria isolated from Arctic sea-ice was studied.The results showed that strain BJ1 belonged to genus Planococcus,which was a genus of low mole percent G C gram-positive bacteria;strain BJ6 belonged to genus Burkholderia of β-proteobacteria and the rest 6 strain all belonged to γ-proteobacteria,of which strain BJ8 was a species of Pseudoalteromonas,strain BJ2-BJ5 and BJ7 were members of genus Psychrobacter.Phylogenetic analysis also indicated that bacteria of genus Psychrobacter of the isolates formed a relatively independent phylogenetic cluster in comparison with other bacteria belonged to genus Psychrobacter. 相似文献
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《极地研究(英文版)》2014,(3)
正1 Aims and Scope Advances in Polar Science(APS)is an international,peer-reviewed journal jointly sponsored by the Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.APS is a comprchensive academic journal dedicated to presentation of multi-disciplinary achievements in Arctic and Antarctic expeditions and research.Its primary purpose is to publish achievements in fundamental research,applied 相似文献
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《山地科学学报》2014,(4):I0004-I0009
<正>AIMS AND SCOPE(Editorial Policy)The Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the world,such as the Tibetan Plateau,the Himalayas,the Alps,the Andes,the Rockies and many other mountain ranges of our planet. 相似文献
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《山地科学学报》2014,(4)
<正>The Journal of Mountain Science(JMS),founded in2004,is an international English-language journal on mountain sciences.JMS is supervised by the Chinese Academy of Sciences(CAS),sponsored by the Chengdu Institute of Mountain Hazards and Environment,CAS,published by Science Press China,and distributed by Springer exclusively throughout the world(excluding Mainland China).The JMS is published bimonthly,fulltexted in SpringerLink and CNKI,indexed/abstracted by 相似文献
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Livestock behaviour in the Pyrenees includes free grazing and a long resting period that provokes the accumulation of dung and urine in some places,so-called camping areas. The aims of this study were （i） to analyze any change in floral composition,and in nutritional and chemical contents of plants in a livestock camping area; and （ii） to relate the floral composition with soil chemical properties. In a linear transect,five sampling zones were established,from the centre of the camping area to the surrounding Nardus stricta-dominant pasture. The above ground plant biomass and the topsoil were sampled in each zone with 6 replicates per zone. Plant species were classified and weighed to calculate above ground biomass,nutritional and chemical contents,and Shannon diversity and evenness indices. Additionally,soils were sampled in two periods,at the beginning and at the end of grazing period. Soil available nutrients （nitrate,ammonium,phosphorus,potassium,calcium and magnesium）,total nitrogen,organic carbon and pH were measured.
Plant chemical contents （protein,lignin and others） were significantly related to the proportions of grasses,legumes and other plants; so,the protein content is positively correlated with legumes plant biomass while lignin content is negatively correlated with grasses. Both plant and soil nutrients increased linearly towards the centre of the camping area. However,the relationship among plant species richness,diversity and evenness relative to its position along the studied transect was bell-shaped. From the outskirts to the centre of the camping area,plants with low nutrient demand were progressively replaced by those with medium and high nutrients demand and by pioneers.
Nardus stricta-dominant pasture has low plant diversity and plant nutrient content as well as a poor soil nutrient availability. The presence of the camping area introduced patches with more soil nutrients and new species in the large spatial scale. However at a small spatial scale,the strong soil nutrien 相似文献
Plant chemical contents （protein,lignin and others） were significantly related to the proportions of grasses,legumes and other plants; so,the protein content is positively correlated with legumes plant biomass while lignin content is negatively correlated with grasses. Both plant and soil nutrients increased linearly towards the centre of the camping area. However,the relationship among plant species richness,diversity and evenness relative to its position along the studied transect was bell-shaped. From the outskirts to the centre of the camping area,plants with low nutrient demand were progressively replaced by those with medium and high nutrients demand and by pioneers.
Nardus stricta-dominant pasture has low plant diversity and plant nutrient content as well as a poor soil nutrient availability. The presence of the camping area introduced patches with more soil nutrients and new species in the large spatial scale. However at a small spatial scale,the strong soil nutrien 相似文献
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文章概略介绍了利用卫星进行定位的原理 ;由卫星信号传播、信号接收和SA政策等引起的理论误差 ;给出了多种快速、高精度定位的工作模式和观测点选择的原则 ;列出了将WGS - 84坐标转换为我国坐标的公式及解算参数的具体方法 ,供读者在GPS工作中参考。 相似文献