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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
2.
M. B. Wright 《The Journal of the Operational Research Society》1989,40(2):187-192
This paper addresses a problem common to all railway networks. Given a fixed train timetable and locomotives (or other forms of traction) of various types, each train must be allocated a locomotive. This paper examines the use of stochastic algorithms for such a problem. Two types of algorithm are used—a simple ‘local improvement’ method, performed successively from randomly chosen starting points, and a ‘simulated annealing’ approach. Both are found to give considerably better results than a deterministic method in current use, and the annealing approach is probably the better stochastic method. 相似文献
3.
A. Grittner J. Szilasi C. R. Alder Wright und C. Thompson 《Fresenius' Journal of Analytical Chemistry》1886,25(1):594-595
Ohne Zusammenfassung 相似文献
4.
N. Wright und W. C. Lee 《Fresenius' Journal of Analytical Chemistry》1940,120(1-2):39-40
Ohne Zusammenfassung 相似文献
5.
One of the most ignored, but urgent and vital challenges confronting society today is the vulnerability of urban areas to extreme events. Current organization of response systems, predominantly based on a command and control model, limits their effectiveness and efficiency. Particularly, in decision‐making processes where a large number of actors may be involved. In this article, a new distributed collaborative decision‐making model is proposed to overcome command and control limitations encountered in stressful, hostile, chaotic, and large‐scale settings. This model was derived by borrowing concepts from the collective decision making of honeybees foraging, a successful process in solving complex tasks within complex settings. The model introduced in this article was evaluated through differential equations, i.e., continuous analysis, and difference equations, i.e., discrete analysis. The most important result found is that the best available option in any large‐scale decision‐making problem can be configured as an attractor, in a distributed and timely manner. We suggest that the proposed model has the potential to facilitate decision‐making processes in large‐scale settings. © 2005 Wiley Periodicals, Inc. Complexity 11:28–38, 2005 相似文献
6.
7.
Water suppression by diffusive attenuation was used to measure Brix in intact cellular tissue of apple and strawberry. Given
the signal-to-noise ratio, the correlation for apple was established without repeated acquisition, so this protocol should
also be useful for rapid, on-line measurements at low spectrometer frequencies. Water suppression by theT
1-Null method fails with cellular tissue because of the considerable variation in the longitudinal relaxation times of vacuolar
and cytoplasmic water. 相似文献
8.
9.
Tracy Noble Ricardo Nemirovsky Cara Dimattia Tracey Wright 《International Journal of Computers for Mathematical Learning》2004,9(2):109-167
In this article, we will describe the results of a study of 6th grade students learning about the mathematics of change. The
students in this study worked with software environments for the computer and the graphing calculator that included a simulation
of a moving elevator, linked to a graph of its velocity vs. time. We will describe how the students and their teacher negotiated
the mathematical meanings of these representations, in interaction with the software and other representational tools available
in the classroom. The class developed ways of selectively attending to specific features of stacks of centimeter cubes, hand-drawn
graphs, and graphs (labeled velocity vs. time) on the computer screen. In addition, the class became adept at imagining the
motions that corresponded to various velocity vs. time graphs. In this article, we describe this development as a process
of learning to see mathematical representations of motion. The main question this article addresses is: How do students learn
to see mathematical representations in ways that are consistent with the discipline of mathematics?
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
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