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Heading control strategy assessment for coaxial compound helicopters

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Chinese Journal of Aeronautics 2019年第9期32卷 2037-2046页

作者： Ye YUAN Douglas thomson Renliang CHEN Richard DUNLOP National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics&AstronauticsNanjing 210016China University of Glasgow Glasgow G12 8QQUnited Kingdom

The coaxial compound helicopter has two possible strategies for heading control: collective differential and rudder deflection. A flight dynamics model is developed to assess the effect of different heading control strategies. This includes the trim characteristics, steady flight performance,controllability, and manoeuvrability. The trim study demonstrates that heading control strategies are less influential on trim results, and the steady flight performance is also not significantly affected by the heading control strategy adopted. The controllability analysis shows although heading bandwidth and phase delay results at various speeds with different heading control strategies are all satisfied, the control derivative of the collective differential decreases as speed increases, and its heading aggressive agility is degraded into Level 3 in high-speed flight. In addition, using collective differential would lead to severe heading-rolling coupling as forward speed increases. On the contrary, the control derivative and aggressive agility of the rudder deflection is improved with forward speed, and there is no evidence of heading-rolling coupling. Finally, the transient turn MissionTask-Element(MTE) is utilized to investigate the heading manoeuvre characteristics in different heading control strategies, which indicates that the collective differential would add the amplitude of control input and the power consumption during this MTE.

关键词： Coaxial compound helicopter Control strategy Handling qualities Helicopter flight dynamics Helicopter performance

Population structure and body condition of White-crested Elaenia(Elaenia albiceps)in relation to habitat in a modiffed Neotropical forest landscape

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Avian Research 2023年第2期14卷 160-165页

作者： Roberto F.thomson Andrew G.Gosler Edward Grey Institute of Field Ornithology Department of ZoologyUniversity of OxfordSouth Parks RoadOX13PSOxfordUK Laboratorio de Ecología de Vida Silvestre Facultad de Ciencias Forestales y Conservacion de la NaturalezaUniversidad de ChileSanta Rosa#11315La PintanaRegion MetropolitanaChile Institute of Human Sciences The Pauling Centre58a Banbury Rd.OxfordOX26QSUK

Despite the widely accepted view that planted forests are valuable habitat for wildlife species,there is a lack of empirical evidence showing the suitability of this novel habitat,especially in relation to plantations of exotic tree ***,little is known about the effects of forest management on the ecology and dynamics of wild populations in the *** the breeding season,the migrant flycatcher White-crested Elaenia is the most abundant bird species in forested landscapes in *** several years we have studied different aspects of these artificial forests in the coastal range of south-central Chile as habitat for the species,particularly in contrast to the native *** general,our results indicate that plantation forests offer a poorer quality habitat,where the density of the species tends to be lower than in the native forest,although a significant edge effect suggests that its quality can be mitigated by planting as a matrix mosaic with native ***,compared to native forests,populations in plantations contained a higher proportion of younger adult individuals maintaining larger territories,and showing poorer body *** suggest that these differences could also have an impact on the birds'longevity and survival.

关键词： Body condition Migrant Planted forests Survival Temperate forests Territory

Portable device to assess dynamic accuracy of global positioning system(GPS)receivers used in agricultural aircraft

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International Journal of Agricultural and Biological Engineering 2014年第2期7卷 68-74页

作者： Steven J.thomson Yanbo Huang Lowrey A.Smith United States Department of Agriculture(USDA) Agricultural Research Service(ARS)Crop Production Systems Research UnitStonevilleMS 38776USA

A device was designed to test the dynamic accuracy of Global Positioning System(GPS)receivers used in agricultural aircraft and other aerial *** system works by directing a sun-reflected light beam from the ground to the aircraft using mirrors.A photo detector points downward from the aircraft to detect the light beam,and photo detection circuitry triggers an event in the guidance system data file at the aircraft’s location corresponding to the precisely georeferenced position on the *** details are presented on the mirror-based light reflection system and photo-electronic circuitry designed to trigger an event in the guidance system’s log *** example application evaluated the horizontal accuracy of a stand-alone GPS receiver by matching dynamic data with data from the aircraft’s guidance *** indicated a 2.16 s lead in position registered by the stand-alone receiver over that registered by the aircraft’s guidance system GPS receiver,which had been previously evaluated to be within 0.13 s of Real-Time Kinematic(RTK)-referenced time and position.

关键词： GPS receiver accuracy agricultural aircraft aerial application remote sensing georeferencing UAV

Efficacy of haptic sutured in-the-bag intraocular lens for intraocular lens-capsule complex stability:a comparison of three insertion methods

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International Journal of Ophthalmology(English edition) 2022年第9期15卷 1468-1475页

作者： Yang Kyung Cho Andrew thomson Balamurali K Ambati Department of Ophthalmology College of MedicineThe Catholic University of KoreaSeoul 06591Republic of Korea Pacific Clear Vision Institute EugeneOregon 97403-1299USA University of Oregon EugeneOregon 97403-1299USA

·AIM:To evaluate the efficacy and stability of haptic sutured in-the-bag intraocular lens(IOL)in eyes with zonular instability.·METHODS:A total 60 eyes of 60 patients were included in this retrospective cohort *** stability in three groups[haptic sutured IOL in the bag,IOL in the bag insertion with haptics oriented toward areas of zonulysis,IOL with capsular tension ring(CTR)in the bag insertion]were compared according to the IOL insertion *** evaluate the IOL stability,the changes of anterior chamber depth(ACD),refraction,contraction of anterior continuous curvilinear capsulotomy(CCC)area,and tilt of IOL were compared.·RESULTS:There was no significant difference in change of ACD(-0.04±0.01 mm in group of haptic sutured IOL,-0.07±0.01 mm in group of CTR insertion)and refraction(0.05±0.05 D in group of haptic sutured IOL,0.37±015 D in group of CTR insertion)between the group of haptic sutured IOL in the bag and CTR insertion *** in comparison of CCC contraction and IOL tilt,CTR insertion group showed less contraction(1.00%±0.52%)and less IOL tilt(2.66°±0.11°)than the group of haptic sutured IOL in the bag(6.32%±1.36%,3.47°±0.11°,respectively).The CTR insertion group showed the least CCC contraction and the least tilt.·CONCLUSION:In eyes with zonular instability,the method of haptic sutured IOL in-the-bag shows comparable stability in ACD and refraction in comparison with IOL with CTR in the bag *** method of IOL only in-thebag insertion shows the largest contraction of CCC and the largest tilt of IOL.

关键词： zonular instability capsular tension ring haptic sutured in the bag

Effect of Niobium on Transformations From Austenite to Ferrite in Low Carbon Steels

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Journal of Iron and Steel Research International 2011年第S1期18卷 208-212页

作者： Parker Sally Rose Andrew West Geoff thomson Rachel Steel Metallurgy Department Tata Steel RD and TSwinden Technology CentreRotherhamS60 3ARUK Department of Materials Loughborough UniversityLoughboroughLE11 3TUUK

Niobium has an important effect on the transformation behaviour,grain size refinement and precipitation strengthening during hot rolling and subsequent cooling in low carbon steels,with even a low content of niobium having a strong effect on the transformation rate from austenite to ***,the effects of niobium on transformation behaviour have not been fully characterised and understood to *** paper examines in detail austenite grain growth as a function of austenitisation time in high strength low alloy (HSLA) steels with three different niobium contents,together with the effect of niobium on the isothermal transformation kinetics from austenite to ferrite as a function of *** is shown that austenite has the slowest grain growth rate in the steel with the highest niobium *** austenite grain sizes are consistent,the steel with the highest niobium content was found to have the slowest transformation rate from austenite to ferrite.

关键词： niobium transformation kinetics austenite grain growth low carbon steels

Aortic valve replacement reduces mortality in moderate aortic stenosis:a systematic review and meta-analysis

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Journal of Geriatric Cardiology 2023年第1期20卷 61-67页

作者： Kyle B Franke Dimple Bhatia Ross L Roberts-thomson Peter J Psaltis Adelaide Medical School The University of AdelaideAdelaideAustralia Vascular Research Centre Lifelong Health ThemeSouth Australian Health and Medical Research InstituteAdelaideAustralia Department of Cardiology Royal Adelaide HospitalAdelaideAustralia

BACKGROUND With the introduction of transcatheter aortic valve replacement and an evolving understanding of the natural progression and history of aortic stenosis,the potential for earlier intervention in appropriate patients is promising;however,the benefit of aortic valve replacement in moderate aortic stenosis remains *** Pubmed,Embase,and the Cochrane Library databases were searched up until 30th of December 2021 using keywords including moderate aortic stenosis and aortic valve *** reporting all-cause mortality and outcomes in early aortic valve replacement(AVR)compared to conservative management in patients with moderate aortic stenosis were *** ratios were generated using random-effects meta-analysis to determine effect *** 3470 publications were screened with title and abstract review,which left 169 articles for full-text *** these studies,7 met inclusion criteria and were included,totalling 4,827 *** studies treated AVR as a time-dependent co-variable in cox-regression multivariate analysis of all-cause *** with surgical or transcatheter AVR was associated with a 45% decreased risk of all-cause mortality(HR=0.55[0.42-0.68],I2=51.5%,P<0.001).All studies were representative of the overall cohort with appropriate sample sizes,with no evidence of publication,detection,or information biases in any of the *** In this systematic review and meta-analysis,we report a 45% reduction in all-cause mortality in patients with moderate aortic stenosis who were treated with early aortic valve replacement compared to a strategy of conservative *** control trials are awaited to determine the utility of AVR in moderate aortic stenosis.

关键词： aortic stenosis analysis

Nanog and transcriptional networks in embryonic stem cell pluripotency

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Cell Research 2007年第1期17卷 42-49页

作者： James A thomson PO Box 7365 WiCell Research Institute WI53715-1299 W153706-1509 1220 Capitol Court USAThe Genome Center of Wisconsin WI 53707-7365 425 Henry Mall The Wisconsin National Primate Research Center University of Wisconsin-Madison The Department of Anatomy WI 53706 470 N.Charter Street University of Wisconsin-Madison Medical School

Several extrinsic signals such as LIF,BMP and Wnt can support the self-renewal and pluripotency of embryonic stem(ES) cells through regulating the"pluripotent genes." A unique homeobox transcription factor,Nanog,is one of the keydownstream effectors of these *** level of Nanog can maintain the mouse ES cell self-renewal indepen-dent of LIF and enable human ES cell growth without feeder *** addition to the external signal pathways,intrinsictranscription factors such as FoxD3,P53 and Oct4 are also involved in regulating the expression of ***,Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that haveimportant functions in ES cell *** key factors form a regulatory network to support or limit each other’sexpression level,which maintains the properties of ES cells.

关键词： Nanog embryonic stem cell pluripotency transcription factor

Characterization of spray deposition and drift from a low drift nozzle for aerial application at different application altitudes

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International Journal of Agricultural and Biological Engineering 2011年第4期4卷 28-33页

作者： Yanbo Huang Steven J.thomson US Department of Agriculture Agricultural Research ServiceCrop Production Systems Research UnitStonevilleMS 38776USA

A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production and protection *** it is difficult to completely characterize spray deposition and drift,these important factors can be estimated with appropriate sampling protocol and *** height is an important variable influencing off-target spray drift,but this variable has not been easily measured or logged.A custom-configured aircraft-mounted laser with logging capabilities makes this *** study was designed to investigate droplet size and deposition characteristics of a low drift CP flat-fan nozzle at application altitudes 3.7 m,4.9 m,and 6.1 *** the study,CP flat-fan nozzles were set to a downward angle of 30 degrees applying a mixture of water,Syl-Tac®adjuvant,and Rubidium Chloride(RbCl)tracer at a 28.5 L/ha application *** droplets were collected using water sensitive paper(WSP)cards placed in the spray *** sheets were also placed in the swath and downwind for drift *** analysis indicated that median droplet diameter as determined by WSP in the spray swath was not significantly influenced by spray application ***,statistical analysis also indicated that concentration of RbCl tracer from Mylar samplers in the spray swath was not significantly influenced by application *** height had a significant effect on spray deposition from drift samplers,along with wind direction and relative *** results for drift samplers may have been influenced by shifts in wind direction that altered the relationship between orientation of samplers and wind.

关键词： deposition spray nozzle aerial application droplet spectra spray drift

Estimation of cotton yield with varied irrigation and nitrogen treatments using aerial multispectral imagery

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International Journal of Agricultural and Biological Engineering 2013年第2期6卷 37-41页

作者： Yanbo Huang Ruixiu Sui Steven J.thomson Daniel K.Fisher Crop Production Systems Research Unit Agricultural Research ServiceUnited States Department of AgricultureStonevilleMS 38776USA

Cotton yield varies spatially within a *** variability can be caused by various production inputs such as soil properties,water management,and fertilizer *** multispectral imaging is capable of providing data and information to study effects of the inputs on yield qualitatively and quantitatively in a timely and cost-effective fashion.A 10-ha cotton field with irrigation and non-irrigation 2×2 blocks was used in this *** nitrogen application treatments were randomized with two replications within each *** plant canopy was closed,airborne multispectral images of the field were acquired using a 3-CCD MS4100 *** images were processed to generate various vegetation *** vegetation indices were evaluated for the best performance to characterize *** effect of irrigation on vegetation indices was *** for yield estimation were developed and verified by comparing the estimated and actual *** indicated that ratio of vegetation index(RVI)had a close relationship with yield(R^(2)=0.47).Better yield estimation could be obtained using a model with RVI and soil electrical conductivity(EC)measurements of the field as explanatory variables(R^(2)=0.53).This research demonstrates the capability of aerial multispectral remote sensing in estimating cotton yield variation and considering soil properties and nitrogen.

关键词： remote sensing multispectral imagery cotton yield nitrogen irrigation soil properties