检索结果-南通市图书馆

Discharge-Stage Relationship on Urban Streams evaluated at USGS Gauging Stations,***,Missouri

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of earth Science 2020年第6期31卷 1133-1141页

作者： Robert e.Criss David L.nelson Department of earth and Planetary Sciences Washington UniversitySt.Louis MO 63130USA Columbia Cir Pasadena CA 91105USA

extensive USGS data tables and detailed,1 m2 Li DAR surveys are used to determine the optimal power n that relates discharge(Q)to stage(h*)above channel bottom(ho)at 39 gauging stations on small streams in the ***,Missouri area,all of which have catchments of 0.6 to 220 *** different methodologies are employed to determine both n and ho:(1)optimizing linearity in a plot of Q1/n *** stage(hL)using USGS field measurements at each site;(2)optimizing linearity in a plot of Q1/n *** using USGS rating tables at each site;(3)a mathematical inverse method applied to the same USGS rating tables;(4)use of Li DAR data on channel geometry to determine the power dependences of channel area A and hydraulic radius H on h*,combined with the Manning and rational equations to predict *** these methods,only methods 2 and 3 compare favorably,and these values compare poorly with Method 1 based on field data,and with method 4 based on theoretical and empirical *** Method 4 is predictive,it provides a useful alternative to methods 1–3 that are based on USGS field measurements,which are heavily weighted toward low *** conclude that the apparent values of n in the USGS rating tables are systematically too low for small streams.

关键词： stream gauging Li DAR topography urban flooding discharge hydrology

Intracellular Transport of Plant Viruses： Finding the Door out of the Cell

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2011年第5期4卷 813-831页

作者： James e. Schoelz Phillip A. Harries Richard S. nelson Division of Plant Sciences University of Missouri Columbia MO 65211 USA Department of Biology Pittsburg State University Pittsburg KS 66762 USA Plant Biology Division The Samuel Roberts Noble Foundation Inc. Ardmore OK 73401 USA

Plant viruses are a class of plant pathogens that specialize in movement from cell to cell. As part of their arsenal for infection of plants, every virus encodes a movement protein （MP）, a protein dedicated to enlarging the pore size of plasmodesmata （PD） and actively transporting the viral nucleic acid into the adjacent cell. As our knowledge of intercellular transport has increased, it has become apparent that viruses must also use an active mechanism to target the virus from their site of replication within the cell to the PD. Just as viruses are too large to fit through an unmodified plasmodesma, they are also too large to be freely diffused through the cytoplasm of the cell. evidence has accumulated now for the involvement of other categories of viral proteins in intracellular movement in addition to the MP, including viral proteins originally associated with replication or gene expression. In this review, we will discuss the strategies that viruses use for intracellular movement from the replication site to the PD, in particular focusing on the role of host membranes for intracellular transport and the coordinated interactions between virus proteins within cells that are necessary for successful virus spread.

关键词： Macromolecular trafficking membrane biology membrane proteins movement proteins plasmodesmata plant-virus interactions.

Advances in Multi-Terabit, Long-Haul WDM Transmission for Terrestrial Networks

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

光学学报 2003年第S1期23卷 546-547页

作者： Benyuan Zhu Lynn e. nelson OFS 791 Holmdel-Keyport Rd Holmdel NJ 07733OFS 791 Holmdel-Keyport Rd Holmdel NJ 07733

This paper reviews the recent advances in multi-terabit long-haul transmission technologies for terrestrial optical networks. The use of high performance new fibres, low-noise Raman amplification, optimised modulation... 详细信息

关键词： for on of WDM Advances in Multi-Terabit Long-Haul WDM Transmission for Terrestrial Networks in

Cloud computing for integrated stochastic groundwater uncertainty analysis

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital earth 2013年第4期6卷 313-337页

作者： Yong Liu Alexander Y.Sun Keith nelson Wesley e.Hipke National Center for Supercomputing Applications University of Illinois at Urbana-ChampaignUrbanaILUSA Bureau of economic Geology University of Texas at AustinAustinTXUSA Arizona Department of Water Resources PhoenixAZUSA

One of the major scientific challenges and societal concerns is to make informed decisions to ensure sustainable groundwater availability when facing deep uncertainties.A major computational requirement associated with this is on-demand computing for risk analysis to support timely *** paper presents a scientific modeling service called‘ModflowOnAzure’which enables large-scale ensemble runs of groundwater flow models to be easily executed in parallel in the Windows Azure *** technical issues were addressed,including the conjunctive use of desktop tools in MATLAB to avoid license issues in the cloud,integration of Dropbox with Azure for improved usability and‘Drop-and-Compute,’and automated file exchanges between desktop and the *** scientific use cases are presented in this paper using this service with significant computational *** case is from Arizona,where six plausible alternative conceptual models and a streamflow stochastic model are used to evaluate the impacts of different groundwater pumping *** case is from Texas,where a global sensitivity analysis is performed on a regional groundwater availability *** of both cases show informed uncertainty analysis results that can be used to assist the groundwater planning and sustainability study.

关键词： MODFLOW groundwatersustainability uncertaintyanalysis global sensitivity analysis cloudcomputing WindowsAzure Dropbox alternative conceptual model cyberinfrastructure eScience

Assessing the utility of dissolved organic matter photoreactivity as a predictor of in situ methylmercury concentration

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2018年第6期30卷 160-168页

作者： Sara J.Klapstein Susan e.Ziegler David A.Risk nelson J.O'Driscoll environmental Science Program Memorial University of Newfoundland Department of earth Sciences St. Francis Xavier University Department of earth and environmental Science Acadia University

Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in June, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in June（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DOM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both Fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on *** DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.

关键词： Methylmercury Dissolved organic carbon Photoreactions Kejimkujik National Park Freshwater lakes

Generation and Propagation of an Urban Flash Flood and Our Collective Responsibilities

在线全文

学校读者我要写书评

暂无评论

Journal of earth Science 2022年第6期33卷 1624-1628页

作者： Robert e.Criss eric M.Stein David L.nelson Department of earth and Planetary Sciences Washington UniversitySt.LouisMO 63130USA 7427 Chamberlain Ave. University CitySt.LouisMO 63130USA 470 Columbia Circle PasadenaCA 91105USA

0 INTRODUCTION Destructive flash flooding is a growing global problem,with dangers being particularly acute in densely populated urban areas. The intensity of rainfall events is increasing, creating high runoff rates ... 详细信息

关键词： Flash flash Generation

Actuator characterization of a man-portable precision maneuver concept

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2014年第2期10卷 141-148页

作者： Ilmars CeLMINS Frank e.FReSCONI Bryant P.nelson US Army Research Laboratory Aberdeen Proving Ground Bowhead Science and Technology Belcamp

The US Army Research Laboratory is conducting research to explore technologies that may be suitable for maneuvering man-portable *** research is focused on the use of rotary actuators with spin-stabilized munitions.A rotary actuator holds the potential of providing a low-power solution for guidance of a spinning *** is in contrast to a linear(reciprocating) actuator which would need to constantly change direction,resulting in large accelerations which in turn would require large forces,thereby driving up the actuator power.A rotational actuator would be operating at a fairly constant rotation rate once it is up to speed,resulting in much lower power *** experiments conducted over a variety of conditions validate the dynamic models of the actuator and supply the data necessary for model parameter *** performance metrics of spin rate response,friction,and power requirements were derived from the *** study indicates that this class of maneuver concepts can be driven with these *** results enable actuator design and multidisciplinary simulation of refined maneuver concepts for a specific application.

关键词：执行器旋转速度特性男子模型参数估计致动器低功率驱动器

Addressing nonresponse bias in forest inventory change estimation using response homogeneity classifications

在线全文

学校读者我要写书评

暂无评论

Forest ecosystems 2023年第1期10卷 125-131页

作者： James A.Westfall Mark D.nelson U.S.Forest Service Northern Research StationYorkPAUSA U.S.Forest Service Northern Research StationSt.PaulMNUSA

estimating amounts of change in forest resources over time is a key function of most national forest inventories(NFI). As this information is used broadly for many management and policy purposes, it is imperative that accurate estimations are made from the survey sample. Robust sampling designs are often used to help ensure representation of the population, but often the full sample is unrealized due to hazardous conditions or possibly lack of land access permission. Potentially, bias may be imparted to the sample if the nonresponse is nonrandom with respect to forest characteristics, which becomes more difficult to assess for change estimation methods that require measurements of the same sample plots at two points in time, i.e., remeasurement. To examine potential nonresponse bias in change estimates, two synthetic populations were constructed: 1) a typical NFI population consisting of both forest and nonforest plots, and 2) a population that mimics a large catastrophic disturbance event within a forested population. Comparisons of estimates under various nonresponse scenarios were made using a standard implementation of post-stratified estimation as well as an alternative approach that groups plots having similar response probabilities(response homogeneity). When using the post-stratified estimators, the amount of change was overestimated for the NFI population and was underestimated for the disturbance population, whereas the response homogeneity approach produced nearly unbiased estimates under the assumption of equal response probability within groups. These outcomes suggest that formal strategies may be needed to obtain accurate change estimates in the presence of nonrandom nonresponse.

关键词： Disturbance Post-stratification Land use conversion Sample bias

economics and Performance of 10 Gb/s Metro Transport Over Mixed Fiber Plant of G.655 NZDF and G.652.C Zero Water-Peak Fibers

在线全文

学校读者我要写书评

暂无评论

光学学报 2003年第S1期23卷 717-718页

作者： Hans-Jrg Thiele Santanu Das Raymond Boncek Lynn e. nelson OFS 791 Holmdel-Keyport Road Holmdel NJ 07733OFS 19 Schoolhouse Road Somerset NJOFS 2000 Northeast Expressway Norcross GAOFS 791 Holmdel-Keyport Road Holmdel NJ 07733

Using lower-cost lasers, 30% savings are possible for 10-Gb/s uncompensated metro transmission over NZDF, compared to G.652 fiber. We present WDM transmission results for a mixed plant of NZDF rings interconnected to ... 详细信息

关键词： of or on as economics and Performance of 10 Gb/s Metro Transport Over Mixed Fiber Plant of G.655 NZDF and G.652.C Zero Water-Peak Fibers dBm DML eML WDM