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Impact of Varying Light and Dew on Ground Cover Estimates from Active NDVI,RGB,and LiDAR

Plant Phenomics 2021年第1期3卷 263-276页

作者： david M.Deery david j.Smith Robert Davy jose A.jimenez-Berni Greg j.Rebetzke Richard A.james CSIRO Agriculture and Food CanberraACTAustralia CSIRO Agriculture and Food YancoNSWAustralia CSIRO Information Management and Technology CanberraACTAustralia Instituto Agricultura Sostenible Consejo Superior de Investigaciones CientificasCordobaSpain

Canopy ground cover(GC)is an important agronomic measure for evaluating crop establishment and early *** study evaluates the reliability of GC estimates,in the presence of varying light and dew on leaves,from three different ground-based sensors:(1)normalized difference vegetation index(NDVI)from the commercially available GreenSeeker®;(2)RGB images from a digital camera,where GC was determined as the portion of pixels from each image meeting a greenness criterion(i.e.,ðGreen−RedÞ/ðGreen+RedÞ>0);and(3)LiDAR using two separate approaches:(a)GC from LiDAR red reflectance(whereby red reflectance less than five was classified as vegetation)and(b)GC from LiDAR height(whereby height greater than 10 cm was classified as vegetation).Hourly measurements were made early in the season at two different growth stages(tillering and stem elongation),among wheat genotypes highly diverse for canopy *** active NDVI showed the least variation through time and was particularly stable,regardless of the available light or the presence of *** addition,between-sample-time Pearson correlations for NDVI were consistently high and significant(P<0:0001),ranging from 0.89 to *** comparison,GC from LiDAR and RGB showed greater variation across sampling times,and LiDAR red reflectance was strongly influenced by the presence of *** times when the light was exceedingly low,correlations between GC from RGB and NDVI were consistently high(ranging from 0.79 to 0.92).The high reliability of the active NDVI sensor potentially affords a high degree of flexibility for users by enabling sampling across a broad range of acceptable light conditions.

关键词： LiDAR reflectance Impact

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Near-UV electroluminescence in unipolar-doped, bipolar-tunneling GaN/AlN heterostructures

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Light(Science & Applications) 2017年第1期6卷 168-174页

作者： Tyler A Growden Weidong Zhang Elliott R Brown david F Storm david j Meyer Paul R Berger Department of Electrical and Computer Engineering The Ohio State UniversityColumbusOhio 43210USA Departments of Physics and Electrical Engineering Wright State UniversityDaytonOhio 45435USA US Naval Research Laboratory WashingtonDC 20375USA

Cross-gap light emission is reported in n-type unipolar GaN/AlN double-barrier heterostructure diodes at room *** different designs were grown on semi-insulating bulk GaN substrates using molecular beam epitaxy(MBE).All samples displayed a single electroluminescent spectral peak at 360 nm with full-width at half-maximum(FWHM)values no greater than 16 nm and an external quantum efficiency(EQE)of≈0.0074%at 18.8 *** contrast to traditional GaN light emitters,p-type doping and p-contacts are completely avoided,and instead,holes are created in the GaN on the emitter side of the tunneling structure by direct interband(that is,Zener)tunneling from the valence band to the conduction band on the collector *** Zener tunneling is enhanced by the high electric fields(~5×106 V cm^(−1))created by the notably large polarization-induced sheet charge at the interfaces between the AlN and GaN.

关键词： AlN GaN heterostructure Near-UV light emission unipolar Zener tunneling

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Theory and methodology for kinematic design of Gough-Stewart platforms

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Science China(Technological Sciences) 1999年第4期42卷 425-436页

作者：黄田汪劲松 david j.Whitehouse School of Engineering University of Warwick Coventry CV4 7AL UK)

The kinematic design issue of Gough-Stewart platforms is investigated. Based upon a full understanding of the geometrical characteristics of workspace boundary, a spherically-shaped prescribed workspace having a given orientation capability is defined for the synthesis of a well behaved workspace. Two performance measures are presented, i.e. the local dexterity and workspace radius ratio. The dimensions of the platform are determined with a prior knowledge of how the design parameters affect the dexterity and workspace radius ratio, resulting in an optimal design in terms of these performance indices. An example of application to the kinematic design of a hexapod machine tool is given to illustrate the effectiveness of this approach.

关键词： Stewart platforms parallel manipulators workspace dexterity optimal design.

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

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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

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Afterword to Semen Analysis in 21st Century Medicine special issue in Asian journal of Andrology

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Asian journal of Andrology 2010年第1期12卷 118-123页

作者： david j. Handelsman Trevor G. Cooper Reproductive Endocrinology ＆ Andrology Director ANZA C Research Institute Sydney Australia Andrology Laboratory Institute of Reproductive Medicine of the University Munster Germany

We summarise and comment on the topics discussed by the contributors to this Special Issue. As an introduction, Ann jequier＇s [ 1 ] generally positive assessment of the new-look manual was tempered with her res- ervations about reference values, on which other chapters dwelt at length. Aspects of laboratory technique were discussed by Charlene Brazil [2], whose offering gives a rare insight into the actual workings of andrology laboratories and highlights the need for greater involvement of laboratory directors （often clinicians） in assessing the quality of data provided.

关键词： no english key word

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Age at reproductive maturity and effect of age and time of day on sex attraction in the potato psyllid Bactericera cockerelli

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Insect Science 2012年第5期19卷 585-594页

作者： Christelle Guedot david R. Horton Peter j. Landolt U.S. Department of Agriculture Agricultural Research Service 5230 Konnowac Pass Road Wapato WA 98951 USA

The potato psyllid, Baetericera （= Paratrioza） cockerelli （gulc）（Hemiptera： Triozidae）, is a major pest of potato. Studies were conducted to determine the age at which both males and females reach reproductive maturity and the effect of age and time of day on sex attraction. Adult B. cockerelli reach reproductive maturity within 48 h post-eclosion, with females being mature on the day of eclosion and males at 1 day post-eclosion. Oviposition generally began 2 days after mating but was delayed when females mated within 2 days post-eclosion. In laboratory olfactometer assays, the age of females used as odor sources and the age of males assayed to these odors did not affect sex attraction, with both younger （1-4-day-old） and older （8-10-day-old） males being attracted to females, regardless of female age （1-4-day-old or 8-10-day-old）. Males assayed to live females at different times during the photophase （between 8：00 and 20：00 hours） were attracted to females between 11：00 and 17：00 hours, showing a temporal periodicity in sex attraction with B. cockerelli at least during the photophase.

关键词： mate attraction olfactometer oviposition periodicity potato preference,Triozidae

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Expanding the SDI environment:comparing current spatial data infrastructure with emerging indoor location-based services

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International journal of Digital Earth 2016年第6期9卷 629-647页

作者： david j.Coleman Abbas Rajabifard Kris W.Kolodziej Department of Geodesy and Geomatics Engineering University of New BrunswickFrederictonCanada Centre for Spatial Data Infrastructures and Land Administration Department of Infrastructure EngineeringThe University of MelbourneMelbourneAustralia Indoor LBS LLC New YorkNYUSA

The authors compare key elements of the emerging field of Indoor Location-Based Services(Indoor LBS)to those currently found in spatial data infrastructure(SDI)*** a brief review of SDIs and Location-Based Services,the corresponding drivers,characteristics and emerging issues within the field of Indoor LBS are introduced and discussed.A comparative framework relates the two in terms of the criteria‘People’,‘Data’,‘Technologies’,‘Standards’and‘Policies/Institutional Arrangements’.After highlighting key similarities and differences,the authors suggested three areas–definition of common framework datasets in Indoor LBS,more effective use of volunteered geographic information by SDI programs and development of appropriate privacy policies by both communities–that may benefit from sharing‘lessons learned’.

关键词： Spatial data infrastructure location-based services indoor positioning mapping geospatial

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Finite-temperature screw dislocation core structures and dynamics in α-titanium

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npj Computational Materials 2023年第1期9卷 12-24页

作者： Anwen Liu Tongqi Wen jian Han david j.Srolovitz Department of Materials Science and Engineering City University of Hong KongHong Kong SARChina Department of Mechanical Engineering The University of Hong KongHong Kong SARChina

A multiscale approach based on molecular dynamics(MD)and kinetic Monte Carlo(kMC)methods is developed to simulate the dynamics of an(a)screw dislocation inα-*** free energy barriers for the core dissociation transitions and Peierls barriers for dislocation glide as a function of temperature are extracted from the MD simulations(based on machine learning interatomic potentials and optimization);these form the input to kMC *** random walk trajectories from kMC agree well with those predicted by *** some planes,dislocations move via a locking-unlocking ***,some dislocations glide in directions that are not parallel with the core dissociation *** MD/kMC multiscale method proposed is applicable to dislocation motion in simple and complex materials(not only screw dislocations in Ti)as a function of temperature and stress state.

关键词： dislocation dynamics locking

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Semi-transparent,flexible,and electrically conductive silicon mesh by capillarity-driven welding of vapor-liquid-solid-grown nanowires over large areas

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Nano Research 2020年第5期13卷 1465-1471页

作者： Thomas A.Celano Seokhyoung Kim david j.Hill james F.Cahoon Department of Chemistry University of North Carolina at Chapel HillChapel HillNC 27599-3290USA

Bottom-up synthesis of semiconductor nanowires(NWs)by the vapor-liquid-solid(VLS)mechanism has enabled diverse technological applications for these *** metallic NWs,however,it has been challenging to form large-area interconnected NW ***,we generate centimeter-scale meshes of mechanically and electrically interconnected Si NWs by sequentially growing,collapsing,and joining the NWs using a capillarity-driven welding *** fabricate meshes from VLS-grown NWs ranging in diameter from 20 to 100 nm and find that the meshes are three-dimensional with a thickness ranging from^1 to^10 microns depending on the NW *** extinction measurements reveal that the networks are semi-transparent with a color that depends on the absorption and scattering characteristics of individual ***,active voltage contrast imaging of both centimeter-and micron-scale meshes reveals widespread electrical *** a sacrificial layer,we demonstrate that the mesh can be liberated from the growth substrate,yielding a highly flexible and transparent *** transport measurements both on the growth substrate and on liberated,flexible films reveal electrical conduction across a centimeter scale with a sheet resistance of^160-180 kΩ/square that does not change significantly upon *** the ability to encode complex functionality in semiconductor NWs through the VLS process,we believe these meshes of networked NWs could find application as neuromorphic memory,electrode scaffolds,and bioelectronic interfaces.

关键词： semiconductor nanowire conductive network flexible electronics welding thermal annealing active-voltage contrast

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Foreword to Semen Analysis in 21st Century Medicine special issue in Asian journal of Andrology

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Asian journal of Andrology 2010年第1期12卷 7-10页

作者： david j. Handelsman Trevor G. Cooper Reproductive Endocrinology ＆ Andrology ANZA C Research Institute Sydney Australia Andrology Laboratory Institute of Reproductive Medicine of the University Munster Germany

Semen analysis as an integral part of infertility investigations has a surprisingly long history, emerging only slowly, from under a cloud of disrepute and occupying a solitary niche outside conventional pathology tests, until relatively recently. From origins in the 19th century when spermatozoa were only identified as present or absent in cervical mucus samples from postcoital tests, even then a practice deemed ＂... dabbling incompatible with decency and self-respect...＂（cited in [1]）.

关键词： no english key word

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