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The existence of arbitrary cohomological localizations on the homotopy category of spaces has remained unproved since Bousfield settled the same problem for homology theories in the decade of 1970. This is related with another open question, namely whether or not every homotopy idempotent functor on spaces is an f-localization for some map f. We prove that both questions have an affirmative answer assuming the validity of a suitable large-cardinal axiom from set theory (Vopěnka's principle). We also show that it is impossible to prove that all homotopy idempotent functors are f-localizations using the ordinary ZFC axioms of set theory (Zermelo-Fraenkel axioms with the axiom of choice), since a counterexample can be displayed under the assumption that all cardinals are nonmeasurable, which is consistent with ZFC. 相似文献
294.
Nikola Popović Dirk Praetorius Anja Schlömerkemper 《Continuum Mechanics and Thermodynamics》2007,19(1-2):67-80
The mathematical and physical analysis of magnetoelastic phenomena is a topic of ongoing research. Different formulae have
been proposed to describe the magnetic forces in macroscopic systems. We discuss several of these formulae in the context
of rigid magnetized bodies. In case the bodies are in contact, we consider formulae both in the framework of macroscopic electrodynamics
and via a multiscale approach, i.e., in a discrete setting of magnetic dipole moments. We give mathematically rigorous proofs
for domains of polygonal shape (as well as for more general geometries) in two and three space dimensions. In an accompanying
second article, we investigate the formulae in a number of numerical experiments, where we focus on the dependence of the
magnetic force on the distance between the bodies and on the case when the two bodies are in contact. The aim of the analysis
as well as of the numerical simulation is to contribute to the ongoing debate about which formula describes the magnetic force
between macroscopic bodies best and to stimulate corresponding real-life experiments.
相似文献
295.
Numerical simulation results are presented for three turbulent jet diffusion flames, stabilized behind a bluff body (Sydney
Flames HM1-3). Interaction between turbulence and combustion is modeled with the transported joint-scalar PDF approach. The
focus of the study is on the impact of the quality of simulation results in physical space on the behavior of two micro-mixing
models in composition space: the Euclidean Minimum Spanning Tree (‘EMST’) model and the modified Curl coalescence dispersion
(‘CD’) model. Profiles of conditional means and variances of thermo-chemical quantities, conditioned on the mixture fraction,
are discussed in the recirculation region and in the neck zone behind. The impact of the flow and mixing fields in physical
space on the mixing model behavior in composition space is strong for the CD model and increases as the turbulence – chemistry
interaction becomes stronger. The EMST conditional profiles, on the contrary, are hardly affected. 相似文献
296.
并行计算机和计算流体力学并行算法 总被引:6,自引:0,他引:6
对研制计算流体力学高效并行算法及软件具有重要意义的并行计算问题提出了导引性的看法.首先综述了并行计算机的主要设计特征并简要描述了市场现有的几种并行系统.接着介绍了一些有关研制并行算法及评价其性能的重要概念.然后讨论了如何使分布式内存并行计算机的运行负载不平衡和通信开销达到最小.最后列举了计算流体力学某些算例的测试结果.本文的重点是结构网格和分程序结构网格的应用,但这些概念和方法对非结构网格同样有效 相似文献
297.
298.
Differentiation between Shallow and Deep Charge Trap States on Single Poly(3‐hexylthiophene) Chains through Fluorescence Photon Statistics 下载免费PDF全文
Kristin S. Grußmayer Florian Steiner Prof. Dr. John M. Lupton Prof. Dr. Dirk‐Peter Herten Dr. Jan Vogelsang 《Chemphyschem》2015,16(17):3578-3583
Blinking of the photoluminescence (PL) emitted from individual conjugated polymer chains is one of the central observations made by single‐molecule spectroscopy (SMS). Important information, for example regarding excitation energy transfer, can be extracted by evaluating dynamic quenching. However, the nature of trap states, which are responsible for PL quenching, often remains obscured. We present a detailed investigation of the photon statistics of single poly(3‐hexylthiophene) (P3HT) chains obtained by SMS. The photon statistics provide a measure of the number and brightness of independently emitting areas on a single chain. These observables can be followed during blinking. A decrease in PL intensity is shown to be correlated with either 1) a decrease in the average brightness of the emitting sites; or 2) a decrease in the number of emitting regions. We attribute these phenomena to the formation of 1) shallow charge traps, which can weakly affect all emitting areas of a single chain at once; and 2) deep traps, which have a strong effect on small regions within the single chains. 相似文献
299.
Inside Back Cover: Differentiation between Shallow and Deep Charge Trap States on Single Poly(3‐hexylthiophene) Chains through Fluorescence Photon Statistics (ChemPhysChem 17/2015) 下载免费PDF全文
300.
Dendritic Glycopolymer as Drug Delivery System for Proteasome Inhibitor Bortezomib in a Calcium Phosphate Bone Cement: First Steps Toward a Local Therapy of Osteolytic Bone Lesions 下载免费PDF全文