On approximate solutions for reflection of waves in a stratified medium     

C. J. Thomson  C. H. Chapman 《Geophysical Journal International》1984,79(2):385-410

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Estimation of the elastic properties of seafloor sediments byinversion of precritical reflection data     

Chapman  N.R. Stinson  K. Levy  S. Cabrera  J. Oldenburg  D.W. 《Oceanic Engineering, IEEE Journal of》1988,13(4):215-221

A method has been presented for estimating the elastic properties of sea-floor sediment by inverting the amplitude-range information of precritical reflection data. The method was tested using synthetic data for reflection from a half-space sediment model and the estimates values for the P- and S-wave speeds and the density were in good agreement with the geoacoustic model parameters. The synthetic data were also used to determine the sensitivity of the method to interference from reflections from subbottom layers. In most practical cases the interference is not likely to be a problem for precritical reflection data. The method was then applied to measurements of seafloor reflection obtained in an experiment carried out off the west coast of Canada. The estimated values of the elastic properties of the topmost sediment layer were consistent with values available from the literature, and with estimates from other experiments carried out in the same region  相似文献   

Geoacoustic model parameter estimation using a bottom-moored hydrophone array     

Barlee  R.M.S. Chapman  N.R. Wilmut  M.J. 《Oceanic Engineering, IEEE Journal of》2005,30(4):773-783

This paper describes results from an experiment carried out to investigate geoacoustic inversion with a bottom-moored hydrophone array located in the shallow waters of the Timor Sea off the northern coast of Australia. The array consisted of two arms in a V shape, horizontally moored at a site that was essentially flat over a large area. Hydrophone positions were estimated using an array element localization (AEL) technique that established relative uncertainties of less than 1 m on the seafloor. The data used for geoacoustic inversion were from experiments with continuous wave (CW) tones in the 80- to 195-Hz band transmitted from a towed projector. A hybrid search algorithm determined the set of geoacoustic model parameters that maximized the Bartlett fit (averaged coherently spatially at each tone and incoherently over frequency) between the measured and modeled data at the array. Due to the long range experimental geometry, the inversion was sensitive to attenuation in the sediment. The inverted geoacoustic profile performed well in a simple test for localizing the sound source at other sites in the vicinity of the array. Range-depth localization performance for the horizontal array was comparable to that for an equivalent vertical array.  相似文献   

Optical and near-infrared integral field spectroscopy of the SCUBA galaxy N2 850.4     

A. M. Swinbank  Ian Smail  R. G. Bower  C. Borys  S. C. Chapman  A. W. Blain  R. J. Ivison  S. Ramsay Howat  W. C. Keel  A. J. Bunker 《Monthly notices of the Royal Astronomical Society》2005,359(2):401-407

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Epsilon Aurigae     

Robert D. Chapman 《Astrophysics and Space Science》1985,110(1):177-182

In April 1984, fourth contact ended the two year long eclipse of Epsilon Aurigae. An astrometric study of the study of the system was carried out by Van de Kamp (1978) leading to the conclusion that the orbit is seen very close to edge on. The eclipse was monitored by a number of groups from the ground and from spacecraft such as the IUE. Ultraviolet observations of the system from IUE have thrown new light on the nature of the system that lead us to conclude that the secondary object is probably a cold, dusty accretion disk surrounding a star that is completely hidden inside the diskCommunication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wihelm Bessel (1784–1846).  相似文献   

Storylines: an alternative approach to representing uncertainty in physical aspects of climate change     

Theodore G. Shepherd  Emily Boyd  Raphael A. Calel  Sandra C. Chapman  Suraje Dessai  Ioana M. Dima-West  Hayley J. Fowler  Rachel James  Douglas Maraun  Olivia Martius  Catherine A. Senior  Adam H. Sobel  David A. Stainforth  Simon F. B. Tett  Kevin E. Trenberth  Bart J. J. M. van den Hurk  Nicholas W. Watkins  Dimitri A. Zenghelis 《Climatic change》2018,147(3-4):555-569

Investigating the relationships between climate extremes and crop yield can help us understand how unfavourable climatic conditions affect crop production. In this study, two statistical models, multiple linear regression and random forest, were used to identify rainfall extremes indices affecting wheat yield in three different regions of the New South Wales wheat belt. The results show that the random forest model explained 41–67% of the year-to-year yield variation, whereas the multiple linear regression model explained 34–58%. In the two models, 3-month timescale standardized precipitation index of Jun.–Aug. (SPI_JJA), Sep.–Nov. (SPI_SON), and consecutive dry days (CDDs) were identified as the three most important indices which can explain yield variability for most of the wheat belt. Our results indicated that the inter-annual variability of rainfall in winter and spring was largely responsible for wheat yield variation, and pre-growing season rainfall played a secondary role. Frequent shortages of rainfall posed a greater threat to crop growth than excessive rainfall in eastern Australia. We concluded that the comparison between multiple linear regression and machine learning algorithm proposed in the present study would be useful to provide robust prediction of yields and new insights of the effects of various rainfall extremes, when suitable climate and yield datasets are available.  相似文献   

Biogeographical drivers of ragweed pollen concentrations in Europe     

Matyasovszky  István  Makra  László  Tusnády  Gábor  Csépe  Zoltán  Nyúl  László G.  Chapman  Daniel S.  Sümeghy  Zoltán  Szűcs  Gábor  Páldy  Anna  Magyar  Donát  Mányoki  Gergely  Erostyák  János  Bodnár  Károly  Bergmann  Karl-Christian  Deák  Áron József  Thibaudon  Michel  Albertini  Roberto  Bonini  Maira  Šikoparija  Branko  Radišić  Predrag  Gehrig  Regula  Rybníček  Ondřej  Severova  Elena  Rodinkova  Victoria  Prikhodko  Alexander  Maleeva  Anna  Stjepanović  Barbara  Ianovici  Nicoleta  Berger  Uwe  Seliger  Andreja Kofol  Weryszko-Chmielewska  Elżbieta  Šaulienė  Ingrida  Shalaboda  Valentina  Yankova  Raina  Peternel  Renata  Ščevková  Jana  Bullock  James M. 《Theoretical and Applied Climatology》2018,133(1-2):277-295

Theoretical and Applied Climatology - The drivers of spatial variation in ragweed pollen concentrations, contributing to severe allergic rhinitis and asthma, are poorly quantified. We analysed the...  相似文献   

Adaptation and development trade-offs: fluvial sediment deposition and the sustainability of rice-cropping in An Giang Province,Mekong Delta     

Alexander D. Chapman  Stephen E. Darby  Hoàng M. Hồng  Emma L. Tompkins  Tri P. D. Van 《Climatic change》2016,137(3-4):593-608

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Magnetic storms: Their geometrical and physical analysis,and their classification     

Sydney Chapman 《Studia Geophysica et Geodaetica》1961,5(1):30-50

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Creel catches of crab, Cancer pagurus L. using different baits     

Chapman  C. J.; Smith  G. L. 《ICES Journal of Marine Science》1978,38(2):226-229

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