排序方式： 共有48条查询结果，搜索用时 0 毫秒
11.
An orderly algorithm combined with clique searching is used to show that there are—up to isomorphism, in all cases—325,062 resolvable 2-(16,4,2) designs with 339,592 resolutions, 19,072,802 2-(13,6,5) designs, and 15,111,019 2-(14,7,6) designs. Properties of the classified designs are further discussed. 相似文献
12.
Approaches for classifying resolvable balanced incomplete block designs (RBIBDs) are surveyed. The main approaches can roughly be divided into two types: those building up a design parallel class by parallel class and those proceeding point by point. With an algorithm of the latter type — and by refining ideas dating back to 1917 and the doctoral thesis by Pieter Mulder — it is shown that the list of seven known resolutions of 2-(28, 4, 1) designs is complete; these objects are also known as the resolutions of unitals on 28 points. This research was supported in part by the Academy of Finland, Grants No. 107493, 110196, and 117499. 相似文献
13.
Petteri Kaski Mahdad Khatirinejad Patric R. J. Östergård 《Designs, Codes and Cryptography》2012,62(3):323-330
Higman asked which block graphs of Steiner triple systems of order v satisfy the 4-vertex condition and left the cases v = 9, 13, 25 unsettled.We give a complete answer to this question by showing that the affine plane of order 3 and the binary
projective spaces are the only such systems. The major part of the proof is to show that no block graph of a Steiner triple
system of order 25 satisfies the 4-vertex condition. 相似文献
14.
We consider 2-(9, 3, ) designs, which are known to exist for all 1, andenumerate such designs for = 5 and their resolutions for 3 5, the smallestopen cases. The number of nonisomorphic such structures obtained is 5 862 121 434, 426, 149 041, and 203 047732, respectively. The designs are obtained by an orderly algorithm, and the resolutions by two approaches:either by starting from the enumerated designs and applying a clique-finding algorithm on two levels or by anorderly algorithm. 相似文献
15.
Let Ψ(t,k) denote the set of pairs (v,λ) for which there exists a graphical t‐(v,k,λ) design. Most results on graphical designs have gone to show the finiteness of Ψ(t,k) when t and k satisfy certain conditions. The exact determination of Ψ(t,k) for specified t and k is a hard problem and only Ψ(2,3), Ψ(2,4), Ψ(3,4), Ψ(4,5), and Ψ(5,6) have been determined. In this article, we determine completely the sets Ψ(2,5) and Ψ(3,5). As a result, we find more than 270,000 inequivalent graphical designs, and more than 8,000 new parameter sets for which there exists a graphical design. Prior to this, graphical designs are known for only 574 parameter sets. © 2006 Wiley Periodicals, Inc. J Combin Designs 16: 70–85, 2008 相似文献
16.
Jussi‐Petteri Suuronen Aki Kallonen Ville Hnninen Merja Blomberg Keijo Hmlinen Ritva Serimaa 《Journal of Applied Crystallography》2014,47(1):471-475
This article describes a novel experimental setup that combines X‐ray microtomography (XMT) scans with in situ X‐ray scattering experiments in a laboratory setting. Combining these two methods allows the characterization of both the micrometre‐scale morphology and the crystallographic properties of the sample without removing it from the setup. Precise control of the position of the sample allows an accurate choice of the scattering beam path through the sample and facilitates the performance of X‐ray scattering experiments on submillimetre‐sized samples. With the present setup, a voxel size of less than 0.5 µm is achievable in the XMT images, and scattering experiments can be carried out with a beam size of approximately 200 × 200 µm. The potential of this setup is illustrated with the analysis of micrometeorite crystal structure and diffraction tomographic imaging of a silver behenate phantom as example applications. 相似文献
17.
Dr. Bernhard Gutmann Dr. Petteri Elsner Dr. Toma Glasnov Dr. Dominique M. Roberge Prof. Dr. C. Oliver Kappe 《Angewandte Chemie (International ed. in English)》2014,53(43):11557-11561
To efficiently drive chemical reactions, it is often necessary to influence an equilibrium by removing one or more components from the reaction space. Such manipulation is straightforward in open systems, for example, by distillation of a volatile product from the reaction mixture. Herein we describe a unique high‐temperature/high‐pressure gas/liquid continuous‐flow process for the rhodium‐catalyzed decarbonylation of aldehydes. The carbon monoxide released during the reaction is carried with a stream of an inert gas through the center of the tubing, whereas the liquid feed travels as an annular film along the wall of the channel. As a consequence, carbon monoxide is effectively vaporized from the liquid phase into the gas phase and stripped from the reaction mixture, thus driving the equilibrium to the product and preventing poisoning of the catalyst. This approach enables the catalytic decarbonylation of a variety of aldehydes with unprecedented efficiency with a standard coil‐based flow device. 相似文献
18.
Switching is a local transformation that when applied to a combinatorial object gives another object with the same parameters.
It is here shown that the cycle switching graph of the 11 084 874 829 isomorphism classes of Steiner triple systems of order
19 as well as the cycle switching graph of the 1 348 410 350 618 155 344 199 680 000 labeled such designs are connected. In
addition to giving an understanding of the multitude of Steiner triple systems—at least for order 19 but perhaps also generally—this
work also presents an algorithm for testing connectedness of large implicit graphs and brings forward a benchmark instance
for such algorithms. 相似文献
19.
Experimental and computational studies of the formation and evolution of scroll waves in three-dimensional excitable media are presented. Scroll waves are initiated in the photosensitive Belousov-Zhabotinsky reaction by perturbing traveling waves transverse to their direction of propagation. Scroll rings are generated by perturbing circular waves, which expand or contract depending on the strength of an imposed excitability gradient and its direction relative to the rotational direction of the scroll wave. (c) 1998 American Institute of Physics. 相似文献
20.
Petteri Harjulehto Tuomo Kuusi Niko Marola 《Journal of Mathematical Analysis and Applications》2008,344(1):504-520
We prove Harnack inequalities for quasiminimizers of the variable exponent Dirichlet energy integral by employing the De Giorgi method. 相似文献