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961.
Mathematische Zeitschrift - In this note, we construct non-isotrivial families of curves of genus $$g\ge 2$$ , where the rank of the unitary summand contained in the Hodge bundle can be as large as... 相似文献
962.
Antonov N. V. Gulitskiy N. M. Kostenko M. M. Lučivjanský T. 《Theoretical and Mathematical Physics》2019,200(3):1294-1312
Theoretical and Mathematical Physics - Using a quantum field theory renormalization group, we consider models of advection of a vector field and a tracer field by a compressible turbulent flow.... 相似文献
963.
In this paper, an unstable linear time invariant (LTI) ODE system is stabilized exponentially by the PDE compensato—a wave equation with Kelvin‐Voigt (K‐V) damping. Direct feedback connections between the ODE system and wave equation are established: The velocity of the wave equation enters the ODE through the variable vt(1,t); meanwhile, the output of the ODE is fluxed into the wave equation. It is found that the spectrum of the system operator is composed of two parts: point spectrum and continuous spectrum. The continuous spectrum consists of an isolated point , and there are two branches of asymptotic eigenvalues: the first branch approaches to , and the other branch tends to ?∞. It is shown that there is a sequence of generalized eigenfunctions, which forms a Riesz basis for the Hilbert state space. As a consequence, the spectrum‐determined growth condition and exponential stability of the system are concluded. 相似文献
964.
Zhang Ning Zhang Bin Pang Yong Yang Hong-Sheng Zong Lu Duan Yong-Xin Zhang Jian-Ming 《高分子科学》2022,40(4):373-383
Chinese Journal of Polymer Science - Macromolecule nanocrystal network and strong interfacial interaction are always beneficial to enhance the mechanical property of polymer-based nanocomposites.... 相似文献
965.
966.
Min Lu Saad Sadiq Daniel J. Feaster Hemant Ishwaran 《Journal of computational and graphical statistics》2018,27(1):209-219
Estimation of individual treatment effect in observational data is complicated due to the challenges of confounding and selection bias. A useful inferential framework to address this is the counterfactual (potential outcomes) model, which takes the hypothetical stance of asking what if an individual had received both treatments. Making use of random forests (RF) within the counterfactual framework we estimate individual treatment effects by directly modeling the response. We find that accurate estimation of individual treatment effects is possible even in complex heterogenous settings but that the type of RF approach plays an important role in accuracy. Methods designed to be adaptive to confounding, when used in parallel with out-of-sample estimation, do best. One method found to be especially promising is counterfactual synthetic forests. We illustrate this new methodology by applying it to a large comparative effectiveness trial, Project Aware, to explore the role drug use plays in sexual risk. The analysis reveals important connections between risky behavior, drug usage, and sexual risk. Supplementary material for this article is available online. 相似文献
967.
Microstructural evolution and grain refinement mechanism in AZ31 magnesium alloy subjected to sliding friction treatment were investigated by means of transmission electron microscopy. The process of grain refinement was found to involve the following stages: (I) coarse grains were divided into fine twin plates through mechanical twinning; then the twin plates were transformed to lamellae with the accumulation of residual dislocations at the twin boundaries; (II) the lamellae were separated into subgrains with increasing grain boundary misorientation and evolution of high angle boundaries into random boundaries by continuous dynamic recrystallisation (cDRX); (III) the formation of nanograins. The mechanisms for the final stage, the formation of nanograins, can be classified into three types: (i) cDRX; (ii) discontinuous dynamic recrystallisation (dDRX); (iii) a combined mechanism of prior shear-band and subsequent dDRX. Stored strain energy plays an important role in determining deformation mechanisms during plastic deformation. 相似文献
968.
969.
The dinuclear zinc complexes as high performance catalysts were used to catalyze phospha-Michael reaction of exocyclic α,β-unsaturated benzocyclic ketones under mild conditions, and the desired products possessing 1-indanones or 1-tetralones skeleton were obtained with excellent enantioselectivities of up to 99%/99% ee and yields of up to 99%. The absolute stereochemistry of the major products catalyzed by (R,R)-L1 was determined to be the (R,R)-configuration by X-ray crystallographic analysis of 3d. A positive nonlinear effect was observed and the possible mechanism was proposed. 相似文献
970.