A ground-based hyperspectral imaging system for characterizing vegetation spectral features

A cropping system is usually characterized by continuous spatio-temporal vegetation variability. Vegetation variability can be detected by changes in several vegetation parameters defined according to purpose. Estimation of these vegetation parameters has been made possible by calculating various vegetation indices (VIs), usually by ratioing, differencing, ratioing differences and sums, or by forming linear combinations of spectral band data. Spectrometers or sensors have been used to acquire visible and infrared spectral properties of vegetation. This paper presents a ground-based hyperspectral imaging system for characterizing vegetation spectral features. The hyperspectral sensor used was a ground-based line sensor, ImSpector (V10-12-102), with a nominal spectral resolution of 1.5–2 nm and a wavelength range of 360–1010 nm. A graphical user interface (GUI) was developed in a MATLAB environment to aid in processing and analysis of acquired multidimensional spectral image data. Issues that arise when applying the imaging system to a particular field include acquiring hyperspectral images, selecting appropriate vegetation features or VIs, and quantifying the selected vegetation features or indices with the GUI developed. Vegetation features extracted by the proposed imaging system contribute not only to monitoring vegetation variability in crop systems, but also provide a potential source of relevant variables that can be used to estimate various vegetation parameters. A study that was set up to investigate the alternate bearing phenomenon of citrus trees illustrates the basic elements of the proposed approach.     

基于SRTM3的MODIS图像几何精校正方法研究

地形地物被高度综合化,只存在超大尺度或大尺度的特征地物,可供选择GCP(地面控制点)的明显地物非常有限,这是中低分辨率遥感图像进行几何精校正面临的最大难题。本文提出了基于SRTM3数据构建与遥感图像几何特征尺度一致的地理参照,对MODIS图像进行几何精校正的方法。首先,利用90 m分辨率的SRTM3进行地形综合,生成250 m像元尺度的DEM并提取地性线,并将其与1∶25万的大型湖泊、大江大河矢量图合并;使用地形光照立体渲染模型 (Hillshade)制作250 m的负立体可视化彩色地形地貌图;集成由3种地理信息要素构成的地理参照数据集。之后,分别选取250和500 m分辨率的MODIS数据,利用亚像元分解与增强技术制作125 m分辨率的假彩色影像。最后,叠加显示地理参照数据集和假彩色卫星图像,目视比对采集控制点,利用自适应三角网控制校正模型对多波段数据进行校正处理,其GCP点集的均方误差达到了431 m。结果表明:250 m分辨率的DEM地性线与MODIS亚像元图像表达的特征地物的几何尺度一致,MODIS图像中能识别的特征地物在SRTM3地性线与大型水系中均能找到,地性线所表达的特征地物点的数量多于遥感图像。与传统的基于基础地理底图选择控制点的方法相比,本文提出的方法更有利于同名地物点的判读和选取,并且操作处理简单,选取的GCP点的坐标精度较高,纠正处理工作效率高。      

Electrospray ionization for mass spectrometry of large biomolecules

Electrospray ionization has recently emerged as a powerful technique for producing intact ions in vacuo from large and complex species in solution. To an extent greater than has previously been possible with the more familiar "soft" ionization methods, this technique makes the power and elegance of mass spectrometric analysis applicable to the large and fragile polar molecules that play such vital roles in biological systems. The distinguishing features of electrospray spectra for large molecules are coherent sequences of peaks whose component ions are multiply charged, the ions of each peak differing by one charge from those of adjacent neighbors in the sequence. Spectra have been obtained for biopolymers including oligonucleotides and proteins, the latter having molecular weights up to 130,000, with as yet no evidence of an upper limit.     

Thermoluminescent determination of prehistoric heat treatment of chert artifacts

In recent years archeologists have become interested in the extent to which prehistoric peoples heat-treated chert prior to shaping it into tools. Thermoluminescent determination of the radiation dose accumulated by an artifact since it was formed or last heated provides a simple, reliable test for such heat treatment. This test can be applied to single artifacts without the need for raw source material for comparison. Results on 25 artifacts from four sites indicate that, for many chert sources, color and luster are not useful indicators of heat treatment by prehistoric peoples.     

Time series analysis of soybean response to varying atmospheric conditions for precision agriculture

Four time-lapse cameras, Bushnell Nature View HD Camera (Bushnell, Overland Park, KS, USA) were installed in a soybean field to track the response of soybean plants to changing weather conditions. The purpose was to confirm if visible spectroscopy can provide useful data for tracking the condition of crops and, if so, whether game and trail time-lapse cameras can serve as reliable crop sensing and monitoring devices. Using the installed cameras, images were taken at 30-min intervals between July 22 and August 1, 2015. Using the RGBExcel software application developed in-house, image data from the R (red), G (green), and B (blue) bands were exported to Microsoft Excel for further processing and analysis. Daytime adjusted green red index data for the plant, based on the R and G data, were plotted against time of image acquisition and also regressed with selected weather parameters. The former showed a rise-and-fall trend with daily peaks around 13:00, while the latter showed a decreasing order of correlation with weather variables as follows: log of solar radiation?>?log of soil surface temperature?>?log of air temperature?>?log of soil temperature at 50-mm depth?>?log of relative humidity. Despite some low correlations, the potential for using game and trail cameras with time-lapse capability to track changes in crop vegetation response under varying conditions is established. The resulting data can be used to develop models that can aid precision agriculture applications. This can be further explored in future studies.     

Monthly composites from Sentinel-1 and Sentinel-2 images for regional major crop mapping with Google Earth Engine

Rapid and accurate access to large-scale, high-resolution crop-type distribution maps is important for agricultural management and sustainable agricultural development. Due to the limitations of remote sensing image quality and data processing capabilities, large-scale crop classification is still challenging. This study aimed to map the distribution of crops in Heilongjiang Province using Google Earth Engine(GEE) and Sentinel-1 and Sentinel-2 images. We obtained Sentinel-1 and Sentinel-2 images from all the covered study areas in the critical period for crop growth in 2018(May to September), combined monthly composite images of reflectance bands, vegetation indices and polarization bands as input features, and then performed crop classification using a Random Forest(RF) classifier. The results show that the Sentinel-1 and Sentinel-2 monthly composite images combined with the RF classifier can accurately generate the crop distribution map of the study area, and the overall accuracy(OA) reached 89.75%. Through experiments, we also found that the classification performance using time-series images is significantly better than that using single-period images. Compared with the use of traditional bands only(i.e., the visible and near-infrared bands), the addition of shortwave infrared bands can improve the accuracy of crop classification most significantly, followed by the addition of red-edge bands. Adding common vegetation indices and Sentinel-1 data to the crop classification improved the overall classification accuracy and the OA by 0.2 and 0.6%, respectively, compared to using only the Sentinel-2 reflectance bands. The analysis of timeliness revealed that when the July image is available, the increase in the accuracy of crop classification is the highest. When the Sentinel-1 and Sentinel-2 images for May, June, and July are available, an OA greater than 80% can be achieved. The results of this study are applicable to large-scale, high-resolution crop classification and provide key technologies for remote sensing-based crop classification in small-scale agricultural areas.     

Radar mapping of mercury: full-disk images and polar anomalies

A random-code technique has been used at Arecibo to obtain delay-Doppler radar images of the full disk of Mercury. Anomalously bright features were found at the north and south poles. The north polar feature is oblong (4 degrees by 8 degrees ) and offset from the pole. The smaller south polar feature is mostly confined to the floor of the crater Chao Meng-Fu. The polar locations and radar properties of these features indicate that they may be produced by volume scattering in ice. The images also reveal a variety of more subdued reflectivity features ranging in size from hundreds to thousands of kilometers; some of these appear to have an impact origin.     

Surface grading of bamboo strips using multi-scale color texture features in eigenspace

In order to achieve high competitive quality of bamboo products, it appears that bamboo strips with naturally different tonalities should be elaborately sorted into different classes according to their global color texture appearance. Inspired by the coarse-to-fine visual perception process of human vision system, this paper proposes a new surface grading approach by integrating the color and texture of bamboo strips based on Gaussian multi-scale space. The multi-scale representations of color texture for the original image of bamboo strips could be obtained and used to construct the multivariate image, each channel of which represents a perceptual observation from different scales. The multivariate image analysis (MIA) techniques are used to extract multi-scale features from the resulting multivariate image data. The characteristic images corresponding to typical classes are selected to build the model of the reference eigenspace. The novel testing images and the training images are all projected onto this reference eigenspace to obtain their representative feature clusters. And the Bhattacharyya distance is used to estimate the similarity of the representative feature clusters between the testing images and the training images in the eigenspace. Then a k-NN classifier is adopted to classify the testing images into the given classes of training images. Comparative experiments have been carried out on a set of actual bamboo strip images and the experimental results verify the effective discrimination of multi-scale color texture eigenspace features and good classification accuracy of the proposed surface grading method.     

ARCHAELOGY: A Victim of the Black Sea Flood Found

Archaeologists are mulling over tantalizing images of what appears to have been a house of wood and mud littered with human artifacts now 91 meters beneath the Black Sea. The find lends further credence to the claims of two oceanographers that a torrent equaling 200 Niagara Falls cascaded from the Mediterranean Sea 7500 years ago, driving Neolithic peoples living along the Black Sea coastline inland. But whether the catastrophe gave rise to the biblical account of Noah's Flood and spread farming into central Europe, as the researchers speculate, we can't yet say.     

Soft X-ray Images of the Solar Corona with a Normal-Incidence Cassegrain Multilayer Telescope

High-resolution images of the sun in the soft x-ray to extreme ultraviolet(EUV) regime have been obtained with normal-incidence Cassegrain multilayer telescopes operated from a sounding rocket in space. The inherent energy-selective property of multilayer-coated optics allowed distinct groups of emission lines to be isolated in the solar corona and the transition region. The Cassegrain telescopes provided images in bands centered at 173 and 256 angstroms. The bandpass centered at 173 angstroms is dominated by emission from the ions Fe IX Fe X. This emission is from coronal plasma in the temperature range 0.8 x 10(6) to 1.4 x 10(6)K. The images have angular resolution of about 1.0 to 1.5 arc seconds, and show no degradation because of x-ray scattering. Many features of coronal structure, including magnetically confined loops of hot plasma, coronal plumes, polar coronal holes, faint structures on the size scale of supergranulation and smaller, and features due to overlying cool prominences are visible in the images. The density structure of polar plumes, which are thought to contribute to the solar wind, has been derived from the observations out to 1.7 solar radii.     

计算机辅助小麦图像识别应用中颜色特征基本参量的表达

在计算机辅助图像处理中，运用颜色特征进行图像的分类和识别是简便而有效的一种方法。然而，颜色特征的表达和提取是否准确、合理直接决定着分类和识别的可靠性。本文在重点分析RGB、HIS和L*a*b*三种常用颜色模式基本参量含义及相互间关系的基础上，结合小麦图像自身的特点，通过对30幅小麦图像在三种颜色模式下的9个基本参量进行主成分分析，建立了应用于小麦图像识别的颜色特征基本参量表达式，并对这三种颜色模式的9个基本参量进行了分类，提出了确定而有意义的表征小麦颜色特征的主成分指标。结果如下：基于第一主成分的分类指标综合表达出小麦冠层的亮绿色特点，分类结果具有较高的准确性和可靠性；第二主成分指标主要表达小麦冠层黄绿颜色变化的特点，能够形成连续的量化指标空间。第三主成分指标主要表达小麦正常绿色的情况，在图像获取亮度差异较小时可以进行小麦正常绿色值的评价。     

Late cretaceous polar wander of the pacific plate: evidence of a rapid true polar wander event

We reexamined the Late Cretaceous-early Tertiary apparent polar wander path for the Pacific plate using 27 paleomagnetic poles from seamounts dated by (40)Ar/(39)Ar geochronology. The path shows little motion from 120 to 90 million years ago (Ma), northward motion from 79 to 39 Ma, and two groups of poles separated by 16 to 21 degrees with indistinguishable mean ages of 84 +/- 2 Ma. The latter phenomenon may represent a rapid polar wander episode (3 to 10 degrees per million years) whose timing is not adequately resolved with existing data. Similar features in other polar wander paths imply that the event was a rapid shift of the spin axis relative to the mantle (true polar wander), which may have been related to global changes in plate motion, large igneous province eruptions, and a shift in magnetic field polarity state.     

基于SVM的多光谱影像与SAR图像融合地物分类研究

多光谱遥感图像反映了不同地物的光谱信息,而SAR图像则反映了地表不同地物的后向散射强度信息。通过二者结合,可以实现优势信息互补,提高遥感影像分类的精度。多光谱影像与单波段单极化SAR图像融合分类有2种策略：一种是将SAR图像作为一个波段加入多光谱影像中进行分类;另一种先把多光谱影像与SAR图像融合,然后对融合后的图像进行分类。以成都市使用支持向量机分类方法对2种分类策略下的分类精度进行验证。结果表明,后者分类精度要高于前者,同时2种分类方法的分类精度都明显高于单独使用多光谱影像的分类精度。     

Galileo encounter with 951 gaspra: first pictures of an asteroid

Galileo images of Gaspra reveal it to be an irregularly shaped object (19 by 12 by 11 kilometers) that appears to have been created by a catastrophic collisional disruption of a precursor parent body. The cratering age of the surface is about 200 million years. Subtle albedo and color variations appear to correlate with morphological features: Brighter materials are associated with craters especially along the crests of ridges, have a stronger 1-micrometer absorption, and may represent freshly excavated mafic materials; darker materials exhibiting a significantly weaker 1-micrometer absorption appear concentrated in interridge areas. One explanation of these patterns is that Gaspra is covered with a thin regolith and that some of this material has migrated downslope in some areas.     

南江黄羊产肉量的相关与回归分析

本文研究了40头南江黄羊(2—2.5岁)的产肉量(胴体重和净肉重)活体性状,胴体各部位重,各内脏器官重等性状的相关关系,用通径分析和多元回归分析法配置了估测南江黄羊产肉量的最优回归方程; 胴体重=0.3195体重+0.0495胸围+0.6983管围-9.6486 (1) 净肉重=0.0985体重+0.2804胴体重+0.7778腰腿重-0.8910 (2) 用一个易测性状预测产肉量的“最优”回归方程:胴体重=0.4659体重-0.8694(Se=0.6339 R~2=0.9734 (3) 净肉重=0.3488体重-0.8566(Se=0.7076 R~2=0.9509) (4) 净肉重=0.7364胴体重-0.0909(Se=0.6317 R~2=0.9610) (5) 实验证明,上述方程具有准确(R~2值均大于0.95),可靠(P<0.001)),简便适用的特点。     

小蠹雄性生殖器玻片标本制作技巧

小蠹虫体微小、外形近似、种间差异不明显。鉴定中如综合外部形态特点和雄性生殖器形态特征则结果会更为可靠、准确。以不同亚科小蠹为试验材料,经过反复试验,取得了制作雄性生殖器标本较好的效果,可为同行提供参考。     

Blood cells preserved in a mummy 2000 years old

Structures resembling red blood cells have been seen in mummies, but have been considered by some to be artifacts or molds. The finding of these structures, admixed with white blood cells, in the blood vessels of a mummified American Indian, confirms the original interpretation of preserved red blood cells.     

Generalized tube model of biased reptation for gel electrophoresis of DNA

A theoretical analysis of the reptational motion of DNA in a gel that includes the effects of molecular fluctuations has been used to explain the main features found in experiments involving periodic inversion of the electric field. The resonance-like decrease of the electrophoretic mobility as a function of pulse duration is related to transient "undershoots" in the orientation of the molecule, in agreement with recent experimental data. These features arise from a delicate interplay of internal and center of mass motion of the molecules under pulsed field conditions, and are important for the separation of DNA molecules in the size range 0.2 to 10 million base pairs.     

Solid-state ice volcanism on the satellites of uranus

Voyager images of the uranian satellites Ariel and Miranda show flow features with morphologies indicating that ice has been extruded to the satellites' surfaces in the solid state. These images provide the first observational evidence for solid-state ice volcanism in the solar system. Topographic profiles have been measured across a number of flow features on Ariel. With a simple model of extrusion, spreading, and cooling of a viscous flow, the initial viscosity of the flow material is found to have been no more than about 10(16) poise, far lower than expected for H(2)O ice at the ambient surface temperatures in the uranian system. Sharply reduced viscosities may have resulted from incorporation of ices like NH(3) or CH(4) in the uranian satellites.     

中国土壤调查结果的地统计特征

【目的】我国于1979—1987年进行了第二次土壤普查（以下简称“二普”）,2005—2017年进行了农田耕层土壤养分调查。两次调查均为地面采样量大的全国性调查。两次调查生成数据是我国目前最精细的土壤资源与质量时空数据。通过地统计检验方法,探讨我国在这两次调查中所获土壤质量数据的地统计检验特征,为这些数据用于表征土壤资源与质量时空分布状况,及其在其他行业和研究领域的应用提供参考。【方法】检验方法是在我国东、南、西、北、中不同地域选取7个代表性类型区,提取7片区在两次调查中获得的土壤剖面点和耕层采样点0—20 cm土层的土壤有机质含量。选择土壤有机质含量作为检验指标的原因之一是有机质含量是最重要土壤质量性状之一,其二该要素可量化表达。剖面点数据源于二普对典型土壤类型的剖面采样,采样特征为优先选取典型土壤类型,全国完成了10万个0—100 cm剖面分层采样、化验。经数据整合和多要素匹配,有6万个剖面点获得坐标。耕层采样点数据源于2005—2017年农田耕层养分调查,采样为网格化均衡分布的大样本量,全国完成了1 000万个有GPS定位坐标的耕层样本。每片区含土壤剖面点500—1 300个,耕层采样点50 000—250 000个。用普通克里格插值方法进行地统计分析和检验。对每片区剖面点和耕层采样点数据分别随机选取80%数据作为训练样本集建模,20%作为验证样本集。将验证样本预测值与实测值进行线性回归,计算R ²（决定系数）和RMSE（均方根误差）,以此评价两组数据表达土壤要素空间分布特征的可靠性和误差。【结果】剖面数据的地统计检验显示,7片区二普剖面点数据表达的有机质含量分布状况可靠性均达极显著水平,但校验集预测值与实测值相关性较差,R ²值较低,为0.223—0.380,RMSE较高。2005—2017年耕层采样点数据地统计检验显示,通过网格化均衡分布和大样本量的地面采样,耕层采样点所获有机质含量分布图的可靠性和预测精度优于剖面点数据,R ²提高,RMSE下降。两组数据地统计结果还显示：尽管相隔30年,两时段调查展现的土壤有机质含量有一定变化,但两组数据反映的各片区土壤有机质含量空间分布总体规律相似。【结论】当土壤调查为网格化均衡分布的大样本量采样时,就表征土壤要素空间分布特征而言,其可靠性和精度较好;二普生成大比例尺土壤专题图数据（土壤图,有机质含量图,pH图,土壤氮、磷、钾养分含量图）和2005—2017年农田耕层养分调查数据均源于网格化均衡分布的大样本量地面调查,可靠性和精度优于二普剖面点数据。但剖面点含数据类别多,具有点坐标,也有可靠的土壤专题图表达,对了解多类别土壤要素空间分布特征极具价值。二普与农田耕层点养分调查间隔约30年,两时段数据有利于了解土壤质量时空演变。本研究还显示,获取精细土壤质量数据需要进行大样本量地面调查和采样,对于表征土壤类型、土体构造等稳定性要素而言,若地面采样量较小,将难以获得可靠性和精度优于二普的数据。从实际需求和我国已有工作基础考虑,今后土壤调查重点可考虑以土壤功能调查或缺区补漏调查为主。