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A theoretical and experimental study of heat transfer to polymer melts flowing through ducts is presented. The mathematical model provides for shear heating and expansion cooling effects for various wall boundary conditions.Experimental results, obtained in tube flow, show reproducible temperature and velocity profiles and the data confirm the predictions of the magnitude of the shear heating and expansion cooling effects.It is concluded that the method can be justified for predicting heat transfer in more complex geometries and some preliminary results are presented. 相似文献
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The generalization of Berezin's Grassmann algebra integral to a Clifford algebra is shown to be translation-invariant in a certain sense. This enables the construction of analogs of twisted convolutions of Grassmann algebra elements and of the Fourier-Weyl transformation, which is an isomorphism from a Clifford algebra to the Grassmann algebra over the dual space, equipped with a twisted convolution product. As an application a noncommutative central limit theorem for states of a Clifford algebra is proved. 相似文献
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This paper examines the behavior of the QZ algorithm which is to be expected when A?λB is close to a singular pencil. The predicted results are fully confirmed by practical experience of using the QZ algorithm on examples of this kind. 相似文献
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An experimental investigation into turbulent heat transfer to pseudoplastic titanium dioxide suspensions in pipes has been carried out. Existing heat transfer correlations, including the analogy equations between heat and momentum transfer, generally predict higher Nusselt and Stanton numbers than those observed experimentally. However, a simplified heat transfer model based on the consideration of the laminar sub-layer at the wall and the turbulent core correlates the heat transfer results for heating as well as cooling. The limitations of the existing analogy equations between heat and momentum transfer are discussed. 相似文献
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Modular polyketide synthases biosynthesise natural products through successive Claisen-type condensations, where one module is responsible for one round of chain extension. This review describes recent findings where this rule of co-linearity is broken, either by one module being bypassed (skipping) or through one module being used for multiple chain extension events (stuttering). 相似文献
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Wilkinson PN Henstock DR Browne IW Polatidis AG Augusto P Readhead AC Pearson TJ Xu W Taylor GB Vermeulen RC 《Physical review letters》2001,86(4):584-587
Using very long baseline interferometry we have searched a sample of 300 compact radio sources for examples of multiple imaging produced by gravitational lensing; no multiple images were found with separations in the angular range 1.5--50 milliarcsec. This null result allows us to place a limit on the cosmological abundance of intergalactic supermassive compact objects in the mass range approximately 10(6)M( middle dot in circle) to approximately 10(8)M( middle dot in circle); such objects cannot make up more than approximately 1% of the closure density ( 95% confidence). A uniformly distributed population of supermassive black holes forming soon after the big bang does not, therefore, contribute significantly to the dark matter content of the Universe. 相似文献