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151.
This paper investigates the complex demographic and social changes that have occurred in the neighborhoods of fast-growing United States metropolitan areas emerging as nodes in megapolitan regions between 1980 and 2010. A neighborhood typology is created using k-means cluster analysis to examine the demographic and housing characteristics, and geographic distribution, of neighborhoods that have existed in rapidly growing metropolitan areas. A socioeconomic index is created using principal component analysis (PCA) to analyze socioeconomic conditions within neighborhoods. Using data from the metropolitan areas of Las Vegas, Nevada; Austin, Texas; and Raleigh, North Carolina, this study identifies five neighborhood types, each of which has distinctive geographic and socioeconomic trends. The geographic orientation of each metropolitan area within their larger megapolitan region appears to have a role in the geography of neighborhood change. The results are also discussed in relation to human ecology, immigration, and economic restructuring. 相似文献
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Walter D. Lambert 《Journal of Geodesy》1949,23(3):274-292
If in imagination we viewed a solar eclipse or the occultation of a star from a point outside the earth, we would see the
shadow of the moon advancing across the face of the earth, the earth meanwhile turning on its axis beneath the shadow. When
some point on the advancing edge of the shadow overtook a given point on the surface of the earth, an observer at that point
would note the beginning of the eclipse or occultation. When the trailing edge of the shadow uncovered that point again, the
observer there would note the end of the eclipse or occultation.
The universal time (as distinguished from the local time) of the beginning or ending would depend on the position of the observer
with reference to the body of the earth, that is, on his ideal geodetic coordinates. These universal times would not depend
in the least on the direction of the observer’s vertical. This fact is the key to the usefulness of eclipses and occultations
for geodetic purposes.
Suppose that the prediction for the times of beginning or ending had been made on the basis of the astronomical latitude and
longitude of the observer. Since there would be in general deflections of the vertical in latitude and longitude, Δπ and Δλ,
these would bring about, even in the absence of any other source of discrepancy, diffe-
This article is at once a condensation and an expansion. It is a condensation of a series of lectures delivered in the winter
and spring of 1947 to members of the U. S. Coast and Geodetic Survey and of the Army Map Service. It is an expansion of a
very informal lecture given before Section III of the International Association of Geodesy, meeting in General Assembly at
Oslo in August, 1948. 相似文献
156.
Walter Wahl 《International Journal of Earth Sciences》1942,32(4-5):550-562
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