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71.
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73.
Jürgen Schönbeçk 《NTM》2004,12(2):80-99
Thomas Fincke (January 6th, 1561–April 24th, 1656), born in Flensburg (Germany), was one of the very most important and significant scientists in Denmark during the
seventeenth century, a mathematician and astrologer and physician in the beginning of modern science, a representative of
humanism and an influentual academic organizer. He studied in Strasbourg (since 1577) and Padua (since 1583) and received
his M.D. in Basel (1587), he practised as a physician throughout his life (since 1587 or 1590) and became a professor at Copenhagen
(1591). But he was best known because of his Geometriae rotundi libri XIIII (1583), a famous book on plane and spherical trigonometry, based not on Euclid but on Petrus Ramus. In this influentual work,
in which Fincke introduced the terms tangent and secant and probable first noticed the Law of Tangents and the so-called Newton-Oppel-Mauduit-Simpson-Mollweide-Gauss-formula,
he showed himself to be „abreast of the mathematics of his time“.
相似文献
74.
Sorin Manolache Petru Eles Zebo Peng 《International journal of parallel programming》2007,35(2):125-156
As feature sizes shrink, transient failures of on-chip network links become a critical problem. At the same time, many applications
require guarantees on both message arrival probability and response time. We address the problem of transient link failures
by means of temporally and spatially redundant transmission of messages, such that designer-imposed message arrival probabilities
are guaranteed. Response time minimisation is achieved by a heuristic that statically assigns multiple copies of each message
to network links, intelligently combining temporal and spatial redundancy. Concerns regarding energy consumption are addressed
in two ways. First, we reduce the total amount of transmitted messages, and, second, we minimise the application response
time such that the resulted time slack can be exploited for energy savings through voltage reduction. The advantages of the
proposed approach are guaranteed message arrival probability and guaranteed worst case application response time. 相似文献
75.
In this paper, we present a static load balancing method for mapping production rules in an expert system onto processors of a message-passing multicomputer. The method uses simulated annealing to achieve a nearly optimal allocation of production rules onto processor nodes. The approach balances the initial rule distribution to avoid higher communication demand among processor nodes at run time. A formal mapping model is developed and a new cost function is defined for the annealing process. New heuristic swap functions and cooling policies are provided to ensure the quality of the annealing process. A software load balancing package, SIMAL, was implemented on a SUN workstation to carry out the benchmark experiments. The overhead associated with this mapping method is O(m In m), where m is the number of rules in the production system. Two benchmark production systems, Toru-waltz and Tourney, are mapped onto a hypercube computer with 32 nodes. Experimental benchmark results verify the effectiveness of the rule mapping method. The method can be applied for distributed artificial intelligence processing or for the parallel execution of cooperating expert systems on a message-passing multicomputer. 相似文献
76.
77.
A fully-dense Cu-75 vol pct ZrW2O8 metal matrix composite was fabricated by hot isostatic pressing of Cu-coated ZrW2O8 particles. A small amount of the high-pressure γ-ZrW2O8 phase was created during the cooldown and depressurization following densification; near complete transformation to γ-ZrW2O8 was achieved by subsequent cold isostatic pressing. The thermal expansion behavior of the composite between 25°C and 325°C
was altered by the cold isostatic pressing treatment, and also depended on the length of time that had passed between thermal
cycles. The measured thermal expansion coefficients within specific temperature ranges varied from −6·10−6 K−1 to far above the thermal expansion coefficient of the copper matrix. The complex temperature-dependent expansion/contraction
behavior could be justified by considering the evolution of phase transformations taking place in the ZrW2O8 phase, which were observed by in-situ synchrotron X-ray diffraction measurements. 相似文献
78.
Central to cost-based competition is the capability to accurately predict the cost of delivering a project. Most literature on cost estimation focuses on specific estimation methods as generic techniques and little attention has been paid to the unique requirements at each project stage. This note attempts to identify the critical factors for effective estimation at various stages of typical construction projects. Drawing from organization control theory and cost estimating literature, this note develops a theoretical framework that identifies the critical factors for effective cost estimation during each project phase of a conventional construction project. The underlying logic is that as a cost estimating effort progresses, both task programmability and output measurability improve. As a result, control effort will shift from input-oriented control to a combination of output and behavior control. 相似文献
79.
Nicolas Clauvelin Basile Audoly Sébastien Neukirch 《Scientific Modeling and Simulation》2007,14(1):95-101
The DNA molecule is modeled as an elastic rod with bending and twisting rigidities, subjected to external tension and twist applied at one end, the other end being clamped. We study the plectonemic equilibrium of such a rod, taking into account the impenetrability constraint. Numerical solutions of this boundary value problem have previously shown that purely elastic models can reproduce the supercoiling response of the DNA molecule. Using a variational approach, we derive analytical formulae for the elastic response of the filament, and extend former numerical results. 相似文献
80.