Counting capelin: a comparison of acoustic density and trawl catchability     

O'Driscoll  R. L.; Rose  G. A.; Anderson  J. T. 《ICES Journal of Marine Science》2002,59(5):1062-1071

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Sub-arcsec 10 μm imaging of β pictoris and other star disk candidates     

P. O. Lagage  E. Pantin 《Experimental Astronomy》1994,3(1-4):57-60

We have used the ESO 10 q224v14h2828p456/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">m camera, TIMMI, to image with a very high angular resolution (PFoV: 0.3q224v14h2828p456/xxlarge8243.gif" alt="Prime" align="MIDDLE" BORDER="0">; FWHM:0.9q224v14h2828p456/xxlarge8243.gif" alt="Prime" align="MIDDLE" BORDER="0">) several main-sequence star disk candidates. Information on the q224v14h2828p456/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-Pictoris dust disk has been obtained in a region largely inaccessible to previous observations: 0–80 AU, with a resolution of about 5 AU after deconvolution. Another promising target for 10 q224v14h2828p456/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">m imaging, 51 Ophiuchi, appears point-like.based on data collected at the European Southern Observatory (ESO), La Silla, Chile  相似文献   

Channel overflows of the Pōhue Bay flow,Mauna Loa,Hawai'i: examples of the contrast between surface and interior lava     

Zinzuni Jurado-Chichay  Scott K. Rowland 《Bulletin of Volcanology》1995,57(2):117-126

A number of overflows from a large lava channel and tube system on the southwest rift zone of Mauna Loa were studied. Initial overflows were very low viscosity gas-rich pq6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0">hoehoe evidenced by flow-unit aspect ratios and vesicle sizes and contents. Calculated volumetric flow-rates in the channel range between 80 and 890 m³/s, and those of the overflows between 35 and 110 m³/s. After traveling tens to hundreds of meters the tops of these sheet-like overflows were disrupted into a surface composed of clinker and pq6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0">hoehoe fragments. After these 'a'q6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0"> overflows came to rest, lava from the interiors was able to break out on to the surface as pq6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0">hoehoe. The surface structure of a lava flow records the interaction between the differential shear rate (usually correlated with the volumetric flow-rate) and viscosity-induced resistance to flow. However, the interior of a flow, being better insulated, may react differently or record a later set of emplacement conditions. Clefts of toothpaste lava occurring within fields of clinker on proximal-type 'a'q6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0"> flows also record different shear rates during different times of flow emplacement. The interplay between viscosity and shear rate determines the final morphological lava type, and although no specific portion of lava ever makes a transition from 'a'q6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0"> back to pq6h925880rx28128/xxlarge257.gif" alt="amacr" align="BASELINE" BORDER="0">hoehoe, parts of a flow can appear to do so.  相似文献   

流速仪信号采集系统设计   总被引：1，自引：1，他引：0       下载免费PDF全文

金福一 《水文》2016,36(1):88-91

介绍了流速仪检定系统的工作原理,分析流速仪信号特点和采集难点,针对流速仪信号受外界干扰信号波形复杂问题,设计信号采集硬件调理电路。针对流速仪信号周期多样性问题,对测频法和测周法进行误差分析和比较,确定在不同速度区间使用不同软件滤波的方法。通过硬件调理电路及软件滤波仿真验证,证明设计的可行性,可有效提高流速仪信号采集的精度,并在单片机平台上完成了硬件设计。  相似文献   

When are relative variograms useful in geostatistics?     

Noel Cressie 《Mathematical Geology》1985,17(7):693-702

The relative variogram has been employed as a tool for correcting a simple kind of nonstationarity, namely that in which local variance is proportional to local mean squared. In the past, this has been linked in a vague way to the lognormal distribution, although if {Z_t; t q647h31/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0"> D}is strongly stationary and normal over a domain D,then clearly {exp (Z_t); t q647h31/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0"> D}will stillbe stationary, but lognormal. The appropriate link is made in this article through a universal transformation principle. More general situations are considered, leading to the use of a q647h31/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">scaled variogram.q647h31/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0">  相似文献   

序半群的（∈,∈∨q）-模糊理想刻画     

袁凤连  ;殷允强 《华东地质学院学报》2014,(3):339-343

从一个新的角度研究了序半群上的（∈,∈∨q）-模糊左理想、（∈,∈∨q）-模糊右理想和（∈,∈∨q）-模糊双理想,并利用这些理想给出了正则序半群的若干刻画定理。  相似文献   

The change in S_q(H) amplitude on Abnormal Quiet Days     

G. M. Brown 《Geophysical Journal International》1986,86(2):467-473

Summary. Analysis of geomagnetic data has shown that the superposed northward magnetic field, which reduces the S _q( H ) amplitude at northern mid-latitude stations on Abnormal Quiet Days, and increases the amplitude at stations on the equatorward side of the S _q focus, builds up in amplitude over four to five days before the AQD occurs, and subsides over a similar period after the AQD. It is inferred indirectly that the azimuthal component B_y of the interplanetary magnetic field varies similarly. Data for the opposite meridian show that the imposed field reverses to a southward direction at lower latitudes. The inferred currents to account for these fields are believed to flow in the ionosphere, but to arise from magnetospheric electric fields induced by the solar wind-transported IMF.  相似文献   

LDPC码及其研究进展   总被引：1，自引：0，他引：1  

廖明  陈发堂 《成都信息工程学院学报》2005,20(2):180-183

对低密度奇偶校验码(LDPC)的结构、编译码原理进行了介绍，并与turbo码进行了简单的比较，最后对目前LDPC码的几个研究方向及其进展作了较详细的论述，指出LDPC码具有很大的发展前景。  相似文献   

基于地理探测器的青藏高原多年冻土分布影响因子分析     

肖瑶  赵林  邹德富  刘世博  马露  应雪  刘艺阗 《冰川冻土》2021,43(1):311-321

多年冻土的分布会受到局地地质、地形地貌和地表覆被等因素的影响。为探究各因子对多年冻土分布的影响强弱,选择青藏高原五个典型多年冻土区为研究区,基于MODIS和SRTM DEM数据提取研究区内2003—2012年平均地表温度、NDVI、地表反照率、积雪日数和坡度、坡向等因子,并采用地理探测器模型研究了各因子对研究区多年冻土分布的影响程度及差异。结果表明：在所有研究区内,地表温度是影响多年冻土分布最强的因子,其次为积雪日数。随着空间尺度范围的增大,坡度和坡向对多年冻土分布的影响逐渐减弱,地表温度的影响则逐渐增强。交互探测结果显示两个因子交互作用对多年冻土分布的影响程度都要大于单因子作用下的影响程度。本研究明确了青藏高原多年冻土分布的区域差异规律,为不同尺度多年冻土分布制图提供理论基础。  相似文献   

Modeling Atmospheric Chemistry: Interactions between Gas-Phase Species and Liquid Cloud/Aerosol Particles     

Rolf Sander 《Surveys in Geophysics》1999,20(1):1-31

For detailed modeling of atmospheric chemistry it is necessary to consider aqueous-phase reactions in cloud droplets and deliquesced aerosol particles. Often, the gas-phase concentration is in equilibrium with the aqueous phase. Then Henryq63334v15748422m/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">s law can be used to describe the distribution between the phases provided that the Henryq63334v15748422m/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">s law coefficient is known. In some cases, thermodynamic equilibrium will not be reached and it is necessary to use kinetic expressions of the rates involved. These rates depend on diffusion constants, accommodation coefficients, Henryq63334v15748422m/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">s law coefficients, particle size distributions, and several other parameters. This review describes how these processes can be treated in computer modeling and how the necessary data can be obtained. Even though it is written primarily for use in modeling atmospheric chemistry, some parts will also be useful for waste water and pesticide control and in other areas where the distribution of chemicals between the aqueous and the gas phase is important.  相似文献