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51.
Anna Góral Lidia Lityńska-Dobrzyńska Marcin Kot 《Journal of Materials Engineering and Performance》2017,26(5):2118-2128
Metal matrix composite coatings obtained by electrodeposition are one of the ways of improving the surfaces of materials to enhance their durability and properties required in different applications. This paper presents an analysis of the surface topography, microstructure and properties (residual stresses, microhardness, wear resistance) of Ni/Al2O3 nanocomposite coatings electrodeposited on steel substrates from modified Watt’s-type baths containing various concentrations of Al2O3 nanoparticles and a saccharin additive. The residual stresses measured in the Ni/Al2O3 coatings decreased with an increasing amount of the co-deposited ceramics. It was established that the addition of Al2O3 powder significantly improved the coatings’ microhardness. The wear mechanism changed from adhesive-abrasive to abrasive with a rising amount of Al2O3 particles and coating microhardness. Nanocomposite coatings also exhibited a lower coefficient of friction than that of a pure Ni-electrodeposited coating. The friction was found to depend on the surface roughness, and the smoother surfaces gave lower friction coefficients. 相似文献
52.
We propose a new encryption algorithm relying on reversible cellular automata (CA). The behavior complexity of CA and their
parallel nature makes them interesting candidates for cryptography. The proposed algorithm belongs to the class of symmetric
key systems.
Marcin Seredynski: He is a Ph.D. student at University of Luxembourg and Polish Academy of Sciences. He received his M.S. in 2004 from Faculty
of Electronics and Information Technology in Warsaw University of Technology. His research interests include cryptography,
cellular automata, nature inspired algorithms and network security. Currently he is working on intrusion detection algorithms
for ad-hoc networks.
Pascal Bouvry, Ph.D.: He earned his undergraduate degree in Economical & Social Sciences and his Master degree in Computer Science with distinction
(’91) from the University of Namur, Belgium. He went on to obtain his Ph.D. degree (’94) in Computer Science with great distinction
at the University of Grenoble (INPG), France. His research at the IMAG laboratory focussed on Mapping and scheduling task
graphs onto Distributed Memory Parallel Computers. Next, he performed post-doctoral researches on coordination languages and
multi-agent evolutionary computing at CWI in Amsterdam. He gained industrial experience as manager of the technology consultant
team for FICS in the banking sector (Brussels, Belgium). Next, he worked as CEO and CTO of SDC (Ho Chi Minh city, Vietnam)
in the telecom, semi-conductor and space industry. After that, He moved to Montreal Canada as VP Production of Lat45 and Development
Director for MetaSolv Software in the telecom industry. He is currently serving as Professor in the group of Computer Science
and Communications (CSC) of the Faculty of Sciences, Technology and Communications of Luxembourg University and he is heading
the Intelligent & Adaptive Systems lab. His current research interests include: ad-hoc networks & grid-computing, evolutionary
algorithms and multi-agent systems. 相似文献
53.
This paper describes a method of rigorous verification of an isolating neighborhood based on computer assisted computations. As an application we study the Kuramoto-Sivashinsky equation. The result of the computer assisted proof was directly used in [9] to prove the existence of heteroclinic solutions of the Kuramoto-Sivashinsky equation. 相似文献
54.
New Results in Minimum-Comparison Sorting 总被引:1,自引:0,他引:1
We prove that sorting 13, 14 and 22 elements requires 34, 38 and 71 comparisons, respectively.
This solves a long-standing problem posed by Knuth in his famous book The Art of Computer Programming,
Volume 3, Sorting and Searching. The results are due to an efficient implementation of an algorithm for
counting linear extensions of a given partial order. We also present some useful heuristics which allow us to
decrease the running time of the implementation. 相似文献
55.
Stott SJ McKenzie KJ Mortimer RJ Hayman CM Buckley BR Bulman Page PC Marken F Shul G Opallo M 《Analytical chemistry》2004,76(18):5364-5369
Biphasic electrode systems are studied for the case of the oxidation of the water-insoluble liquid N,N-didodecyl-N',N'-diethylphenylenediamine (DDPD) neat and dissolved in bis(2-ethylhexyl) phosphate (HDOP) and immersed in aqueous electrolyte media. The oxidation process in the absence of HDOP is accompanied by transfer of the anion (perchlorate or phosphate) from the water into the organic phase. However, in the presence of HDOP, oxidation is accompanied by proton exchange instead. This electrochemically driven proton exchange process occurs over a wide pH range. Organic microdroplet deposits of DDPD in HDOP at basal plane pyrolytic graphite electrodes are studied by voltammetric techniques and compared in their behavior to organic microphase deposits in mesoporous TiO2 thin films. The mesoporous TiO2 thin film acts as a host for the organic liquid and provides an alternative biphasic electrode system compared to the random microdroplet/graphite system. Two types of mesoporous TiO2 thin-film electrodes, (i) a 300-400-nm film on ITO and (ii) a 300-400-nm film on ITO sputter-coated with a 20-nm porous gold layer, are investigated. 相似文献
56.
We have considered the role of charge-density-pseudogap for phonon-mediated super-conductivity on two-dimensional lattice. The propagators that enter generalized Eliashberg equations have been renormalized to account for quasi-particle energies related to the formation of the pseudogap, which has been assumed to be of d-wave symmetry. We have evaluated the superconducting transition temperature Tc as a function of doping. It occurs that Tc for d-wave symmetry well reflects experimental behavior. Our results for the isotope shift exponent show that at low doping, the presence of the pseudogap may contribute to > 1/2 as well as to > 1/2 values. 相似文献
57.
Analysis of VME-Bus communication protocol - RTCP-net approach 总被引:1,自引:0,他引:1
Marcin Szpyrka 《Real-Time Systems》2007,35(1):91-108
The paper discusses an RTCP-net approach to design and analysis of an example of VMEbus communication protocol. RTCP-nets are a novel Petri net class, based on time coloured Petri nets but were defined to give users powerful tools for easy and rapid design of real-time systems. Page templates are one of the main advantages of the new nets' design stage. Just modifying values of parameters in the page hierarchy graph is enough to change some features of a modelled system. Therefore, it is easy to experiment on different versions of the same model with very little additional effort. It is also very easy to reorganize page templates in order to model a different structure of a system.Relevant definitions and main properties of RTCP-nets are presented in the paper. A VMEbus communication protocol case study is used to demonstrate some applications of this approach.The work is carried out within KBN Research Project, Grant No. 4 T11C 035 24.
Marcin Szpyrka received the M.S. degree in mathematics from the Rzeszów University (Poland) in 1997. He received the Ph. D. degree in computer science from AGH University of Science and Technology in Kraków (Poland) in 2000. Marcin Szpyrka is currently an assistant professor at the Institute of Automatics, AGH-UST. His research interests include: formal methods (Petri nets, process algebras), real-time systems and safety-critical systems. He has published over 40 papers and one book. 相似文献
58.
A solution to the infinite-horizon min–max model predictive control (MPC) problem of constrained polytopic systems has recently been defined in terms of a sequence of free control moves over a fixed horizon and a state feedback law in the terminal region using a time-varying terminal cost. The advantage of this formulation is the enlargement of the admissible set of initial states without sacrificing local optimality, but this comes at the expense of higher computational complexity. This article, by means of a counterexample, shows that the robust feasibility and stability properties of such algorithms are not, in general, guaranteed when more than one control move is adopted. For this reason, this work presents a novel formulation of min–max MPC based on the concept of within-horizon feedback and robust contractive set theory that ensures robust stability for any choice of the control horizon. A parameter-dependent feedback extension is also proposed and analysed. The effectiveness of the algorithms is demonstrated with two numerical examples. 相似文献
59.
Marcin Witczak Andrzej Obuchowicz Józef Korbicz 《International journal of control》2013,86(13):1012-1031
System identification is one of the most important research directions. It is a diverse field which can be employed in many different areas. One of them is the model-based fault diagnosis. Thus, the problems of system identification and fault diagnosis are closely related. Unfortunately, in both cases, the research is strongly oriented towards linear systems, while the problem of identification and fault diagnosis of non-linear dynamic systems still remains open. There are, of course, many more or less sophisticated approaches to this problem, although they are not as reliable and universal as those related to linear systems, and the choice of the method to be used depends on the application. The purpose of this paper is to provide a new system identification framework based on a genetic programming technique. Moreover, a fault diagnosis scheme for non-linear systems is proposed. In particular, a new fault detection observer is presented, and the Lyapunov approach is used to show that the proposed observer is convergent under certain conditions. It is also shown how to use the genetic programming technique to increase the convergence rate of the observer. The final part of this paper contains numerical examples concerning identification of chosen parts of the evaporation station at the Lublin Sugar Factory S.A., as well as state estimation and fault diagnosis of an induction motor. 相似文献
60.
Marcin Witczak Vicenç Puig Saúl Montes de Oca 《International journal of control》2013,86(10):1788-1799
In this paper, an active fault-tolerant control scheme is proposed in the case of actuator faults. In particular, the general idea of integrating fault identification and control schemes, which takes into account the fault estimation error is first presented in a linear context. As a result, the so-called separation principle for the controller and the fault identification scheme is developed. Subsequently, the proposed approach is extended to a class of non-linear systems. Similarly to the linear case, it is proven that using a suitable control strategy and a faulty identification scheme it is possible to obtain an integrated fault-tolerant control framework, which takes into account the fault identification error. As a result, a non-linear counterpart of the above-mentioned separation principle is developed. Finally, the last part of the paper shows the application results obtained using a twin-rotor system that confirm the high performance of the proposed approach. 相似文献