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21.
Thomas Kleinknecht 《Berichte zur Wissenschaftsgeschichte》1986,9(3):147-160
The various scholarly and scientific endeavours — comprising both arts and sciences —, which British statesmen persued in their leisure time, transcend the mere biographical aspect. In the light of the slow, yet steady professionalisation of educational and political institutions, many of them modernised or newly created in order to achieve what came to be called “National Efficiency”, the literary and scientific pastimes of men, like Gladstone, Morley, Salisbury, Balfour or Haldane, seemed soon to become somewhat obsolete. Yet, it is argued, that the often professedly amateurish activities did not merely display the traditional hobby attitude to the sciences, so characteristic of the wealthy aristocrat, but in some cases revealed a good understanding of the scientific and educational needs of society, leading up to their active advancement. The British amateurs, it would seem, were pleading for providing a balanced higher education and training, rather than going for the technical excellence of the political rival Imperial Germany, which dazzled and, at the same time, intimidated some of them. 相似文献
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This paper critically reviews the existing literature on multiple-trip journeys, and clarifies the need for an improved conceptualization and modeling strategy. It also suggests different ways that trip chaining can be treated and a theory constructed. Exploratory studies, from the 1960s and 1970s, are briefly surveyed (Section I). While they developed the existence and complexity of travel patterns, they lacked any comprehensive theoretical framework. However, they were useful in that they supported the conceptual framework of various kinds of stochastic processes used by transportation scientists to replicate trip-chaining behavior (Section II). Scientists subsequently improved their conceptualization of the issue by grounding individual behavior on the principle of utility maximization. In this latter area the economists have emphasized theoretical concerns while transportation researchers have emphasized operationality (Section III). 相似文献
30.
The p-median problem is a powerful tool in analyzing facility location options when the goal of the location scheme is to minimize the average distance that demand must traverse to reach its nearest facility. It may be used to determine the number of facilities to site, as well as the actual facility locations. Demand data are frequently aggregated in p-median location problems to reduce the computational complexity of the problem. Demand data aggregation, however, results in the loss of locational information. This loss may lead to suboptimal facility location configurations (optimality errors) and inaccurate measures of the resulting travel distances (cost errors). Hillsman and Rhoda (1978) have identified three error components: Source A, B, and C errors, which may result from demand data aggregation. In this article, a method to measure weighted travel distances in p-median problems which eliminates Source A and B errors is proposed. Test problem results indicate that the proposed measurement scheme yields solutions with lower optimality and cost errors than does the traditional distance measurement scheme. 相似文献