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941.
George A. van Otten 《The Professional geographer》1980,32(1):63-71
In the post-World War II era the need to achieve satisfactory economies of scale has led to fever but larger farms in the Willamette Valley. Vigorous demand for farm land by the nonfarm sector has served to inflate land values. As a result, farmers have turned to leasing and renting as alternatives to land purchase. Difficulty in finding suitable land with which to enlarge farm operations has led to the use of noncontiguous fields. 相似文献
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Arno P. Schoenmakers † A. G. de Bruyn H. J. A. Röttgering H. van der Laan C. R. Kaiser 《Monthly notices of the Royal Astronomical Society》2000,315(2):371-380
We present four Mpc-sized radio galaxies which consist of a pair of double-lobed radio sources, aligned along the same axis, and with a coinciding radio core. We call these peculiar radio sources 'double-double' radio galaxies (DDRGs) and propose a general definition of such sources: a 'double-double' radio galaxy consists of a pair of double radio sources with a common centre. Furthermore, the two lobes of the inner radio source must have a clearly extended, edge-brightened radio morphology. Adopting this definition, we find several other candidate DDRGs in the literature. We find that in all sources the smaller (inner) pair of radio lobes is less luminous than the larger (outer) pair, and that the ratio of 1.4-GHz flux density of these two pairs appears to be anticorrelated with the projected linear size of the inner source. Also, the outer radio structures are large, exceeding 700 kpc. We discuss possible formation scenarios of the DDRGs, and we conclude that an interruption of the jet-forming central activity is the most likely mechanism. For one of our sources (B 1834+620) we have been able observationally to constrain the length of time of the interruption to a few Myr. We discuss several scenarios for the cause of the interruption, and suggest multiple encounters between interacting galaxies as a possibility. Finally, we discuss whether such interruptions help the formation of extremely large radio sources. 相似文献
945.
Summary This paper discusses the causes of the current wave of renewal and relocation of football stadiums in the Netherlands and tries to shed some light on the changing form and location of Dutch football stadiums. Comparison with developments in the United Kingdom shows not only remarkable resemblances and mutual influences, but also some significant differences. In an inextricable upward spiral of causes and consequences such as recent successes of clubs and the national team, rising attendances, increasingly positive media attention, rising interests of commercial investors, new international and national requirements on stadium construction and an increasingly positive attitude of municipalities, a new wave of stadium redevelopment and relocation has emerged in the Netherlands. In this paper it will become clear that every stadium tells its own story; some of these stories are highlighted. 相似文献
946.
P. M. Williams K. A. van der Hucht 《Monthly notices of the Royal Astronomical Society》2000,314(1):23-32
A spectroscopic search for luminous companions to WC9-type Wolf–Rayet stars making circumstellar dust reveals the presence of absorption lines attributable to companions in the blue spectra of WR 69 (HD 136488) and WR 104 (Ve2–45). Comparison of spectra of WR 104 observed in 1995 and 1997 showed the absorption lines to be more conspicuous in the latter observation and the emission lines weaker, suggesting a selective eclipse of the WC9 star similar to that observed by Crowther in 1996. The WC9 emission-line spectra are shown to be less uniform than previously thought, showing a significant range of O ii line strengths. The only two WC9 stars in the observed sample that do not make circumstellar dust, WR 81 (He3–1316) and WR 92 (HD 157451), are found to have anomalously weak O ii and strong He ii lines. We suggest that these spectroscopic differences may reflect a compositional difference that plays a role in determining which of the WC9 stars make dust. 相似文献
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A 2-phases neural prediction method for wave overtopping is developed. The ‘classifier’ predicts whether overtopping occurs or not, i.e. q = 0 or q > 0. If the classifier predicts overtopping q > 0, then the ‘quantifier’ is used to determine the mean overtopping discharge. The overtopping database set up within the EC project CLASH (De Rouck, J., Geeraerts, J., 2005. CLASH Final Report, Full Scientific and Technical Report, Ghent University, Belgium) is used to train the networks of the prediction method. 相似文献
950.
Dr. L. van Werveke 《International Journal of Earth Sciences》1925,16(6):468-485
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