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51.
52.
Ping Y Shepherd R Lasinski BF Tabak M Chen H Chung HK Fournier KB Hansen SB Kemp A Liedahl DA Widmann K Wilks SC Rozmus W Sherlock M 《Physical review letters》2008,100(8):085004
We report the first direct measurements of total absorption of short laser pulses on solid targets in the ultrarelativistic regime. The data show an enhanced absorption at intensities above 10(20) W/cm(2), reaching 60% for near-normal incidence and 80%-90% for 45 degrees incidence. Two-dimensional particle-in-cell simulations demonstrate that such high absorption is consistent with both interaction with preplasma and hole boring by the intense laser pulse. A large redshift in the second harmonic indicates a surface recession velocity of 0.035c. 相似文献
53.
54.
Anna K. Yanchenko Graham Tierney Joseph Lawson Christoph Hellmayr Andrew Cron Mike West 《商业与工业应用随机模型》2023,39(3):292-309
Forecasting enterprise-wide revenue is critical to many companies and presents several challenges and opportunities for significant business impact. This case study is based on model developments to address these challenges for forecasting in a large-scale retail company. Focused on multivariate revenue forecasting across collections of supermarkets and product categories, hierarchical dynamic models are natural: these are able to couple revenue streams in an integrated forecasting model, while allowing conditional decoupling to enable relevant and sensitive analysis together with scalable computation. Structured models exploit multi-scale modeling to cascade information on price and promotion activities as predictors relevant across categories and groups of stores. With a context-relevant focus on forecasting revenue 12 weeks ahead, the study highlights product categories that benefit from multi-scale information, defines insights into when, how, and why multivariate models improve forecast accuracy, and shows how cross-category dependencies can relate to promotion decisions in one category impacting others. Bayesian modeling developments underlying the case study are accessible in custom code for interested readers. 相似文献
55.
In this paper we are concerned with solutions, in particular with univalent solutions, of the Loewner differential equation
associated with non-normalized subordination chains on the Euclidean unit ball B
n
in
\mathbbCn{\mathbb{C}^n}. The main result is a generalization to higher dimensions of a well known result due to Becker. Various particular cases
of this result have been recently obtained for subordination chains with normalization Df(0,t)=etIn{Df(0,t)=e^tI_n} or Df(0, t) = e
tA
, t ≥ 0, where
A ? L(\mathbbCn,\mathbbCn){A\in L(\mathbb{C}^n,\mathbb{C}^n)}. We also determine the form of the standard solutions to the Loewner differential equation associated with generalized spirallike
mappings. In the last section we obtain the form of the solution in the presence of coefficient bounds. 相似文献
56.
Abstract The infrared spectra (700–100 cm?1) of the complexes [M(ox)2(H2O)2] (ox = 8-hydroxyquinolinate anion, M = Mn, Fe, Co, Ni, Cu, Zn) are discussed. For the purposes of assignment of the metal ligand modes, deuterated 8-hydroxyquinoline-d 7 was prepared by the Skraup synthesis and the spectra of the deuterated complexes were compared with those of the unlabelled species. Furthermore, [64Zn(ox)2(H2O)2] and [68Zn(ox)2(H2O)2] were prepared by reaction of 64ZnSO4 and 68ZnSO4 with 8-hydroxyquinoline and the effects of metal isotope labelling on the spectra were examined and compared with earlier isotopic data on the nickel and zinc complexes. 相似文献
57.
Philip S. Hall Graham E. Jackson John R. Moss David A. Thornton Paul F. M. Verhoeven Gareth M. Watkins 《光谱学快报》2013,46(7):1247-1267
Abstract The infrared spectra (4000 - 50 cm?1) of the square planar rhodium(I) complexes cis-[Rh(CO)2 (pyridine) (X)] (X = Cl, Br) and their isotopomers with pyridine-d 5 and 13CO have been determined. Assignments are based on earlier studies on pyridine and its complexes and on the shifts in infrared bands which are caused by the isotopic substitutions employed. Normal coordinate analysis following the procedure of Becher and Mattes has been used to confirm the empirical assignments. The two v(RhC) bands are observed near 490 and 450 cm?1. v(RhN) is found near 210 cm?1 and v(RhX) occurs at 310 (X = Cl) and 235 (X = Br) cm?1. At frequencies below 200 cm?1, the bands are assigned to bending modes in the following sequence: δ (RhN) > δ (CRhC) > δ (RhCl) > γ (RhCl) > γ (RhN). 相似文献
58.
Yoshikazu Okamoto Graham J. Kemp Tomonori Isobe Eisuke Sato Yuji Hirano Junichi Shoda Manabu Minami 《Magnetic resonance imaging》2014
Several studies have proposed the cell membrane as the main water diffusion restricting factor in the skeletal muscle cell. We sought to establish whether a particular form of exercise training (which is likely to affect only intracellular components) could affect water diffusion. The purpose of this study is to characterise prospectively the changes in diffusion tensor imaging (DTI) eigenvalues of thigh muscle resulting from hybrid training (HYBT) in patients with non-alcoholic fatty liver disease (NAFLD). Twenty-one NAFLD patients underwent HYBT for 30 minutes per day, twice a week for 6 months. Patients were scanned using DTI of the thigh pre- and post-HYBT. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), the three eigenvalues lambda 1 (λ1), λ2, λ3, and the maximal cross sectional area (CSA) were measured in bilateral thigh muscles: knee flexors (biceps femoris (BF), semitendinosus (ST), semimembranous (SM)) and knee extensors (medial vastus (MV), intermediate vastus (IV), lateral vastus (LV), and rectus femoris (RF)), and compared pre- and post-HYBT by paired t-test. Muscle strength of extensors (P < 0.01), but not flexors, increased significantly post-HYBT. For FA, ADC and eigenvalues, the overall picture was of increase. Some (P < 0.05 in λ2 and P < 0.01 in λ1) eigenvalues of flexors and all (λ1-λ3) eigenvalues of extensors increased significantly (P < 0.01) post-HYBT. HYBT increased all 3 eigenvalues. We suggest this might be caused by enlargement of muscle intracellular space. 相似文献
59.
Summary. In this paper we describe and analyse a class of spectral methods, based on spherical polynomial approximation, for second-kind
weakly singular boundary integral equations arising from the Helmholtz equation on smooth closed 3D surfaces diffeomorphic
to the sphere. Our methods are fully discrete Galerkin methods, based on the application of special quadrature rules for computing
the outer and inner integrals arising in the Galerkin matrix entries. For the outer integrals we use, for example, product-Gauss
rules. For the inner integrals, a variant of the classical product integration procedure is employed to remove the singularity
arising in the kernel. The key to the analysis is a recent result of Sloan and Womersley on the norm of discrete orthogonal
projection operators on the sphere. We prove that our methods are stable for continuous data and superalgebraically convergent
for smooth data. Our theory includes as a special case a method closely related to one of those proposed by Wienert (1990)
for the fast computation of direct and inverse acoustic scattering in 3D.
Received May 29, 2000 / Revised version received March 26, 2001/ Published online December 18, 2001 相似文献
60.
Optimized prefactored compact schemes 总被引:1,自引:0,他引:1
The numerical simulation of aeroacoustic phenomena requires high-order accurate numerical schemes with low dispersion and dissipation errors. In this paper we describe a strategy for developing high-order accurate prefactored compact schemes, requiring very small stencil support. These schemes require fewer boundary stencils and offer simpler boundary condition implementation than existing compact schemes. The prefactorization strategy splits the central implicit schemes into forward and backward biased operators. Using Fourier analysis, we show it is possible to select the coefficients of the biased operators such that their dispersion characteristics match those of the original central compact scheme and their numerical wavenumbers have equal and opposite imaginary components. This ensures that when the forward and backward stencils are added, the original central compact scheme is recovered. To extend the resolution characteristic of the schemes, an optimization strategy is employed in which formal order of accuracy is sacrificed in preference to enhanced resolution characteristics across the range of wavenumbers realizable on a given mesh. The resulting optimized schemes yield improved dispersion characteristics compared to the standard sixth- and eighth-order compact schemes making them more suitable for high-resolution numerical simulations in gas dynamics and computational aeroacoustics. The efficiency, accuracy and convergence characteristics of the new optimized prefactored compact schemes are demonstrated by their application to several test problems. 相似文献