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51.
Security under man-in-the-middle attacks is extremely important when protocols are executed on asynchronous networks, as the Internet. Focusing on interactive proof systems, one would like also to achieve unconditional soundness, so that proving a false statement is not possible even for a computationally unbounded adversarial prover. Motivated by such requirements, in this paper we address the problem of designing constant-round protocols in the plain model that enjoy simultaneously non-malleability (i.e., security against man-in-the-middle attacks) and unconditional soundness (i.e., they are proof systems).We first give a construction of a constant-round one-many (i.e., one honest prover, many honest verifiers) concurrent non-malleable zero-knowledge proof (in contrast to argument) system for every NP language in the plain model. We then give a construction of a constant-round concurrent non-malleable witness-indistinguishable proof system for every NP language. Compared with previous results, our constructions are the first constant-round proof systems that in the plain model guarantee simultaneously security against some non-trivial concurrent man-in-the-middle attacks and against unbounded malicious provers. 相似文献
52.
Hao WangAuthor VitaeJens B. SchmittAuthor Vitae Ivan MartinovicAuthor Vitae 《Performance Evaluation》2011,68(2):201-219
During the last two decades, starting with the seminal work by Cruz, network calculus has evolved as a new theory for the performance analysis of networked systems. In contrast to classical queueing theory, it deals with performance bounds instead of average values and thus has been the theoretical basis of quality of service proposals such as the IETF’s Integrated and Differentiated Services architectures. Besides these it has, however, recently seen many other application scenarios as, for example, wireless sensor networks, switched Ethernets, avionic networks, Systems-on-Chip, or even to speed-up simulations, to name a few.In this article, we extend network calculus by adding a new versatile modeling element: a demultiplexer. Conventionally, demultiplexing has been either neglected or assumed to be static, i.e., fixed at the setup time of a network. This is restrictive for many potential applications of network calculus. For example, a load balancing based on current link loads in a network could not be modeled with conventional network calculus means. Our demultiplexing element is based on stochastic scaling. Stochastic scaling allows one to put probabilistic bounds on how a flow is split inside the network. Fundamental results on network calculus with stochastic scaling are therefore derived in this work. We illustrate the benefits of the demultiplexer in a sample application of uncertain load balancing. 相似文献
53.
In the area of membrane computing, time-freeness has been defined as the ability for a timed membrane system to produce always
the same result, independently of the execution times associated to the rules. In this paper, we use a similar idea in the
framework of spiking neural P systems, a model inspired by the structure and the functioning of neural cells. In particular,
we introduce stochastic spiking neural P systems where the time of firing for an enabled spiking rule is probabilistically
chosen and we investigate when, and how, these probabilities can influence the ability of the systems to simulate, in a reliable
way, universal machines, such as register machines. 相似文献
54.
Ivan Marsa-Maestre Miguel A. Lopez-Carmona Juan R. Velasco 《Service Oriented Computing and Applications》2008,2(4):167-185
Service Oriented Architectures, which allow for the integration of different subsystems and of applications running on different
devices and platforms, may be very suitable to solve the problem of service personalization in large smart environments like
cities, where the number of potential users and potentially available services is rapidly growing. Taking this into account,
we have designed an agent-based service oriented architecture for smart spaces. Two of the greatest challenges in the design
of such a solution are providing effective device, service and context federation and composition mechanisms and handling
user mobility. For the first challenge, we have designed a hierarchical architecture and developed a set of inheritance, aggregation
and access mechanisms for devices, services and context. To handle user mobility, we have followed three different strategies,
using stationary, mobile or nomadic agents. In this paper, we describe the main aspects of our architecture and perform an experimental evaluation to determine
the advantages and drawbacks of the different strategies. 相似文献
55.
Jovanović I Ugrenović S Antić S Stefanović N Mihailović D 《Microscopy research and technique》2007,70(7):617-627
Psammoma bodies (PBs) are one of many choroids plexus aging changes. The aim of our research was to perform the quantification of PBs' presence in human choroids plexus stroma, as well as to evaluate the characteristics of choroids plexus stroma in cases in which PBs were present. Afterwards, the observations of the histochemical analysis would be confirmed by immunohistochemical analysis. Choroid plexuses of 30 cadavers were used for the histochemical and, choroids plexuses of 15 cadavers in which PBs' presence was confirmed during the histochemical analysis, were used as material for the immunohistochemical analysis. Light microscopy, histochemical, immunohistochemical, and morphometric method were applied during the study. Classification of the cases was performed by cluster analysis. We observed increase of choroids plexus PBs' presence during the aging process. But this increase is not linear. Their presence is the largest in the second cluster that is younger than the third and older than the first. Nuclear morphometric parameters of the stroma in these cases showed that the cellular composition in this cluster is different than in other two and, that contain larger number of lymphoid cells. Immunohistochemical analysis showed PBs' positive reaction on vimentin, CD45R0, and LCA markers, while in their vicinity, as well as inside them, numerous T-cells were observed. So, the presence of CD45R0 and LCA-positive T cells, PBs' positive reaction on the same markers, indirectly connect these cells with PBs' formation process. 相似文献
56.
Ivan Bozovic 《Journal of Superconductivity》1991,4(2):193-197
A novel optical method for accurate monitoring of the carrier densityN in layered conductors is introduced. It is applied to several cuprate superconductors, and it is found thatT
c
doesnot scale withN. However, if the closely spaced pairs or triplets of CuO2 planes were coupled together to act as distinct metallic slabs, the relevant variable could ben, theslab carrier density. Indeed, we found thatT
c
does scale nicely withn. This suggests that high-T
c
superconductivity is effectively a two-dimensional phenomenon; it can occur in a cuprate slab which is only one unit cell thick. Finally, estimates are obtained for the length scales of localization of charge carriers:d 8 Å andd
2 Å in all the cuprates under study. 相似文献
57.
Peter Sussner Estev?o L. Esmi Ivan Villaverde Manuel Gra?a 《Journal of Mathematical Imaging and Vision》2012,42(2-3):134-149
Many well-known fuzzy associative memory (FAM) models can be viewed as (fuzzy) morphological neural networks (MNNs) because they perform an operation of (fuzzy) mathematical morphology at every node, possibly followed by the application of an activation function. The vast majority of these FAMs represent distributive models given by single-layer matrix memories. Although the Kosko subsethood FAM (KS-FAM) can also be classified as a fuzzy morphological associative memory (FMAM), the KS-FAM constitutes a two-layer non-distributive model. In this paper, we prove several theorems concerning the conditions of perfect recall, the absolute storage capacity, and the output patterns produced by the KS-FAM. In addition, we propose a normalization strategy for the training and recall phases of the KS-FAM. We employ this strategy to compare the error correction capabilities of the KS-FAM and other fuzzy and gray-scale associative memories in terms of some experimental results concerning gray-scale image reconstruction. Finally, we apply the KS-FAM to the task of vision-based self-localization in robotics. 相似文献
58.
M. Jergel T. Melíšek H Allárová D. I. Belyj V. P. Kutepov A. J. Izrailev D. Synak J. Neuschl J. Ivan 《Journal of Materials Science》1982,17(6):1579-1584
The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO2 substrate and/or Nb3Sn tape superconductor prepared from such a substrate has been studied. The results have shown that the Nb3Sn grains are much finer in the case of Nb-ZrO2, than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200 %, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 cm and the relative elongation decreased from 5 to 3 %. 相似文献
59.
Jepsen T.C. Laplante P.A. Williams J. Christensen K. Ferrante D. Chang J.M. Miller G. 《IT Professional》2004,6(4):10-17
What will software look like in the future? To answer this question, we conducted a survey of our editorial and industrial advisory boards, as well as a few outsiders. We constructed a set of 13 questions that we thought reflected the original query. We then circulated these questions to our boards, with a request to respond to the questions, or be extend them with additional are questions as appropriate. The answers were far ranging and sometimes surprising. 相似文献
60.
In this paper we investigate on the existence of the stabilizing solution of the algebraic Riccati equation (ARE) related to the
filtering problem with a prescribed attenuation level γ. It is well known that such a solution exists and is positive definite for γ larger than a certain γF and it does not exist for γ smaller than a certain γ0. We consider the intermediate case γ(γ0,γF] and show that in this interval the stabilizing solution does exist, except for a finite number of values of γ. We show how the solution of the ARE may be employed to obtain a minimum-phase J-spectral factor of the J-spectrum associated with the
filtering problem. 相似文献