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**排序方式：**共有804条查询结果，搜索用时 15 毫秒

1.

We present a two-sorted algebra, called a

*Peirce algebra*, of relations and sets interacting with each other. In a Peirce algebra, sets can combine with each other as in a Boolean algebra, relations can combine with each other as in a relation algebra, and in addition we have both a set-forming operator on relations (the Peirce product of Boolean modules) and a relation-forming operator on sets (a cylindrification operation). Two applications of Peirce algebras are given. The first points out that Peirce algebras provide a natural algebraic framework for modelling certain programming constructs. The second shows that the so-called*terminological logics*arising in knowledge representation have evolved a semantics best described as a calculus of relations interacting with sets. 相似文献2.

The famous Antosik-Mikusinski convergent theorem on the Abel topological groups has very extensive applications in measure theory, summation theory and other analysis fields. In this paper, we establish the theorem on a class of effect algebras equipped with the ideal topology. This paper shows also that the ideal topology of effect algebras is a useful topology in studying the quantum logic the- ory. 相似文献

3.

Hua-Chieh Li 《Applicable Algebra in Engineering, Communication and Computing》2007,18(4):313-348

In this paper, we give a general criterion to determine when a complex space-time block code has a ring structure and then
we provide a complete list of complex space-time block codes which have ring structures up to size 4. 相似文献

4.

We present a fictitious domain decomposition method for the fast solution of acoustic scattering problems characterized by a

*partially*axisymmetric sound‐hard scatterer. We apply this method to the solution of a mock‐up submarine problem, and highlight its computational advantages and intrinsic parallelism. A key component of our method is an original idea for addressing a Neumann boundary condition in the general framework of a fictitious domain method. This idea is applicable to many other linear partial differential equations besides the Helmholtz equation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献5.

N. S. Nikitchenko 《Cybernetics and Systems Analysis》2003,39(1):97-112

Predicates that preserve their values on a larger (extended) body of data are called equitone. An algebra of such predicates is constructed, a system of its generators is specified, and a complete system of transformations of identities is defined. The results obtained are used for construction and investigation of complete classes of compositions of various types and levels of abstractions that are used in logics of partial predicates. 相似文献

6.

Dental amalgams are based on a broad spectrum of materials differing in their chemical composition, metallurgical treatment, and in the way the initial alloys powders are prepared. In addition to their chemical composition, amalgams based on various powders differ in both their microstructure and the amount of mercury needed for preparation. All these facts may affect electrochemical processes occurring during their interaction with oral fluids, and also mercury release. While verifying the effect of the technology used for the preparation of the high‐copper ternary alloy powder on the properties of resulting amalgams, this study aimed at the mechanism of their interaction with a model saliva solution as well as mercury release was included. Measurements were done in a model saliva solution using standard electrochemical methods and exposition measurements. The interaction of individual types of amalgams with artificial saliva did not reveal any significant differences. The free corrosion potential of all these amalgams in an aerated solution settled in the range of values in which tin oxidation, resulting in a layer of insoluble corrosion producsts, turned out to be the dominant anodic process. The rate of mercury release was the lowest for amalgams based on a gas‐atomized alloy. The highest rate of mercury release, and also its dependence on time, was exhibited by lathe‐cut powder based amalgam. In addition to different volume fraction of the Ag‐Hg phase and the level of its tin alloying, this different behaviour may be explained by differences in the rate at which a layer of tin corrosion products acting as a barrier to mercury release is formed. 相似文献

7.

Hai-Yang Li Sheng-Gang Li 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(5):487-492

This paper is devoted to congruences and ideals in pseudoeffect algebras. Let

*I*be a normal ideal in a pseudoeffect algebra*E*. We show that: (1) the relation ~_{ I }induced by*I*is a congruence if and only if for every*a*∈*E*,*I*∩ [0,*a*] is upper directed; (2) the relation ~_{ I }induced by*I*is a strong congruence if and only if*I*is a normal weak Riesz ideal in a pseudoeffect algebra*E*. Moreover, we introduce a stronger concept of congruence—namely Riesz strong congruence—and we prove that, if*I*is a normal weak Riesz ideal in a pseudoeffect algebra*E*, then ~_{ I }is a Riesz strong congruence and, conversely, if ~ is a Riesz strong congruence, then*I*= [0]_{~}is a normal weak Riesz ideal, and ~_{ I }= ~. This work was supported by the National Natural Science Foundation of China (Grant No. 10271069). 相似文献8.

There are two popular approaches to specifying the semantics of process algebras: labelled transition semantics and

*reaction semantics*. While the notion of*free name*is rather unproblematic for labelled transition semantics this is not so for reaction semantics in the presence of a*structural congruence*for unfolding recursive declarations.We show that the standard definition of free name is not preserved under the structural congruence. We then develop a*fixed point approach*to the set of free names and show that it is*invariant*under the structural congruence. 相似文献9.

Based on a rearrangement inequality by Hardy, Littlewood, and Polya, we define two-operator algebras for independent random variables. These algebras are called Huffman algebras since the Huffman algorithm on these algebras produces an optimal binary tree that minimizes the weighted lengths of leaves. Many examples of such algebras are given. For the case with random weights of the leaves, we prove the optimality of the tree constructed by the power-of-2 rule, i.e., the Huffman algorithm assuming identical weights, when the weights of the leaves are independent and identically distributed. 相似文献

10.

Julia Peas-Martínez María N. Barrachina Ernesto Jos Cuenca-Zamora Gins Luengo-Gil Susana Beln Bravo Eva Caparrs-Prez Raúl Teruel-Montoya Jos Eliseo-Blanco Vicente Vicente ngel García Irene Martínez-Martínez Francisca Ferrer-Marín 《International journal of molecular sciences》2021,22(4)

Exosomes are extracellular vesicles that contain nucleic acids, lipids and metabolites, and play a critical role in health and disease as mediators of intercellular communication. The majority of extracellular vesicles in the blood are platelet-derived. Compared to adults, neonatal platelets are hyporeactive and show impaired granule release, associated with defects in Soluble N-ethylmaleimide-sensitive fusion Attachment protein REceptor (SNARE) proteins. Since these proteins participate in biogenesis of exosomes, we investigated the potential differences between newborn and adult plasma-derived exosomes. Plasma-derived exosomes were isolated by ultracentrifugation of umbilical cord blood from full-term neonates or peripheral blood from adults. Exosome characterization included size determination by transmission electron microscopy and quantitative proteomic analysis. Plasma-derived exosomes from neonates were significantly smaller and contained 65% less protein than those from adults. Remarkably, 131 proteins were found to be differentially expressed, 83 overexpressed and 48 underexpressed in neonatal (vs. adult) exosomes. Whereas the upregulated proteins in plasma exosomes from neonates are associated with platelet activation, coagulation and granule secretion, most of the underexpressed proteins are immunoglobulins. This is the first study showing that exosome size and content change with age. Our findings may contribute to elucidating the potential “developmental hemostatic mismatch risk” associated with transfusions containing plasma exosomes from adults. 相似文献