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1.
An optimal control model of exhaustible resources is used to clarify the long run relationship between mineral rent and depletion cost at the industry level. A standard first order condition of the time rate of change of rents is reformulated to reveal that rent data may be used to help forecast the rise in extraction costs resulting from resource depletion. This application of the theory of exhaustible resources is illustrated using historical mineral industry rent and extraction cost data. A forecast of U.S. coal extraction costs, following the method proposed in this paper, suggests that future rates of extraction cost increases will be similar to rates experienced in the past. 相似文献
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Starting with a partition of a rectangular box into subboxes, it is shown how to construct a natural tetrahedral (type-4) partition and associated trivariate C 1 quintic polynomial spline spaces with a variety of useful properties, including stable local bases and full approximation power. It is also shown how the spaces can be used to solve certain Hermite and Lagrange interpolation problems. 相似文献
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Efficiencies of the maximum pseudolikelihood estimator and a number of related estimators for the case-cohort sampling design in the proportional hazards regression model are studied. The asymptotic information and lower bound for estimating the parametric regression parameter are calculated based on the effective score, which is obtained by determining the component of the parametric score orthogonal to the space generated by the infinite-dimensional nuisance parameter. The asymptotic distributions of the maximum pseudolikelihood and related estimators in an i.i.d. setting show that these estimators do not achieve the computed asymptotic lower bound. Simple guidelines are provided to determine in which instances such estimators are close enough to efficient for practical purposes. 相似文献
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Trivariate Cr macroelements defined in terms of polynomials of degree 8r + 1 on tetrahedra are analyzed. For r = 1,2, these spaces reduce
to well-known macroelement spaces used in data fitting and in the finite-element method.
We determine the dimension of these spaces, and describe stable local minimal determining sets and nodal minimal determining
sets. We also show that the spaces approximate smooth functions to optimal order. 相似文献
9.
Charles L. Watkins Larry K. Krannich Colacot J. Thomas Dileep Srivastava 《Polyhedron》1994,13(24):3299-3307
The reactions of (Me2AlH)3 with Me2AsNMe2, MeAs(NMe2)2, and As(NMe2)3 were investigated as a function of time at room temperature and over the temperature range −90 to 24°C by use of 1H and 13C NMR spectroscopy. (Me2AlH)3 was found to be very reactive toward the aminoarsines, even at −90°C, and no stable Me2AlH-aminoarsine adducts were observed. Instead, the initial stages of the reactions involved AS---N bond cleavage with the generation of highly reactive AlN- and AsH-bonded species. The subsequent course of each reaction and the final arsenic-containing product distribution depended upon the original AL:N stoichiometric ratio and the respective aminoarsine. When the Al:N ratio was 1:1, the reactions were straightforward for each aminoarsine. However, in every case, [Me2AlNMe2]2 was the final AlN-containing product. Independent reactions were carried out to verify many of the proposed decomposition pathways that lead to thermodynamically stable products. The results of this study are compared with those of the analogous, previously reported (Me3Al)2-aminoarsine systems. Additionally, a new synthetic route to [Me2AlAsMe2]3 has been established from the reaction of (Me2AlH)3 with Me2AsH. 相似文献
10.
D ← X resonance enhanced three-photon excitation spectrum of iodine was observed by a cw intracavity absorption technique. Vibrational quantum numbers of D ← X transitions are given for every major spectral feature. The corresponding one-photon enhancement from the B state is evident from the one-photon vibrational assignment. The spectroscopic constants for the D state are v00 = 40 998 cm?1 ω′0 = 113 cm?1 and ω′0χ′0 = 0.045 cm?. 相似文献