Disorder chaos in spin glasses

We investigate numerically disorder chaos in spin glasses, i.e. the sensitivity of the ground state to small changes of the random couplings. Our study focuses on the Edwards-Anderson model in d=1,2,3 and in mean-field. We find that in all cases, simple scaling laws, involving the size of the system and the strength of the perturbation, are obeyed. We characterize in detail the distribution of overlap between ground states and the geometrical properties of flipped spin clusters in both the weak and strong chaos regime. The possible relevance of these results to temperature chaos is discussed.Comment: 7 pages, 8 figures, replaced with accepted versio

Ultrametric probe of the spin-glass state in a field

We study the ultrametric structure of phase space of one-dimensional Ising spin glasses with random power-law interaction in an external random field. Although in zero field the model in both the mean-field and non-mean-field universality classes shows an ultrametric signature [Phys. Rev. Lett. 102, 037207 (2009)], when a field is applied ultrametricity seems only present in the mean-field regime. The results for the non-mean field case in an external field agree with data for spin glasses studied within the Migdal-Kadanoff approximation. Our results therefore suggest that the spin-glass state might be fragile to external fields below the upper critical dimension.Comment: 5 pages, 4 figures, 1 tabl

Modyfikacja powierzchni stopu Ti-6Al-4V metodą PEO-EPD w zawiesinie ZrSiO4

Investigations on the surface modification of the Ti-6Al-4V alloy by plasma electrolytic oxidation are reported here. The oxidation process was carried out in a solution containing a zirconium silicate (ZrSiO4) suspension and sodium hydroxide (NaOH). Anodising was realised at voltages in a range from 100 V to 250 V. It was found that the morphology of the sample surface did not change during the oxidation of the alloy at 100 V. Application of voltages higher than 100 V led to the incorporation of zirconium silicate into the formed oxide layer and to significant changes of the surface morphology

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Herein, a study of the plasma electrolytic oxidation (PEO) of niobium in an anodising bath composed of potassium silicate (K2SiO3) and potassium hydroxide (KOH) is reported. The effects of the K2SiO3 concentration in the bath and the process voltage on the characteristics of the obtained oxide layers were assessed. Compact, barrier-type oxide layers were obtained when the process voltage did not exceed the breakdown potential of the oxide layer. When this threshold was breached, the morphology of the oxide layer changed markedly, which is typical of PEO. A significant amount of silicon, in the form of amorphous silica, was incorporated into the oxide coatings under these conditions compared with the amount obtained with conventional anodising. This surface modification technique led to an improvement in the corrosion resistance of niobium in Ringer’s solution, regardless of the imposed process conditions

Phase Transitions and Computational Difficulty in Random Constraint Satisfaction Problems

We review the understanding of the random constraint satisfaction problems, focusing on the q-coloring of large random graphs, that has been achieved using the cavity method of the physicists. We also discuss the properties of the phase diagram in temperature, the connections with the glass transition phenomenology in physics, and the related algorithmic issues.Comment: 10 pages, Proceedings of the International Workshop on Statistical-Mechanical Informatics 2007, Kyoto (Japan) September 16-19, 200

DICE: Exploiting All Bivariate Dependencies in Binary and Multary Search Spaces

Although some of the earliest Estimation of Distribution Algorithms (EDAs) utilized bivariate marginal distribution models, up to now, all discrete bivariate EDAs had one serious limitation: they were constrained to exploiting only a limited O(d) subset out of all possible O(d2) bivariate dependencies. As a first we present a family of discrete bivariate EDAs that can learn and exploit all O(d2) dependencies between variables, and yet have the same run-time complexity as their more limited counterparts. This family of algorithms, which we label DICE (DIscrete Correlated Estimation of distribution algorithms), is rigorously based on sound statistical principles, and particularly on a modelling technique from statistical physics: dichotomised multivariate Gaussian distributions. Initially (Lane et al. in European Conference on the Applications of Evolutionary Computation, Springer, 1999), DICE was trialled on a suite of combinatorial optimization problems over binary search spaces. Our proposed dichotomised Gaussian (DG) model in DICE significantly outperformed existing discrete bivariate EDAs; crucially, the performance gap increasingly widened as dimensionality of the problems increased. In this comprehensive treatment, we generalise DICE by successfully extending it to multary search spaces that also allow for categorical variables. Because correlation is not wholly meaningful for categorical variables, interactions between such variables cannot be fully modelled by correlation-based approaches such as in the original formulation of DICE. Therefore, here we extend our original DG model to deal with such situations. We test DICE on a challenging test suite of combinatorial optimization problems, which are defined mostly on multary search spaces. While the two versions of DICE outperform each other on different problem instances, they both outperform all the state-of-the-art bivariate EDAs on almost all of the problem instances. This further illustrates that these innovative DICE methods constitute a significant step change in the domain of discrete bivariate EDAs

Production of foamed polypropylene products with metal inserts

Przedstawiono wyniki prac dotyczących możliwości produkcji innowacyjnych kształtek otrzymywanych ze spienionego polipropylenu z metalowymi wkładkami. Projekt obejmował zarówno prace projektowe badawczo-rozwojowe jak i prace wdrożeniowe na linii produkcyjnej. W wyniku prac badawczo-rozwojowych prowadzonych przez firmę IZOBLOK S.A. potwierdzono możliwość otrzymywania rozwiązania w postaci wzmocnionych kształtek z EPP.Results of work dealing with the possibility of producing innovative EPP (foamed polypropylene) profiles with metal inserts are presented in the paper. The project included both design part and its implementation in a process line. As a result of research and development work carried out by IZOBLOK, the possibility of obtaining reinforced EPP parts was confirmed

Potts glass on random graphs

We solve the q-state Potts model with anti-ferromagnetic interactions on large random lattices of finite coordination. Due to the frustration induced by the large loops and to the local tree-like structure of the lattice this model behaves as a mean-field spin glass. We use the cavity method to compute the temperature-coordination phase diagram and to determine the location of the dynamic and static glass transitions, and of the Gardner instability. We show that for q≥ 4 the model possesses a phenomenology similar to the one observed in structural glasses. We also illustrate the links between the positive- and the zero-temperature cavity approaches, and discuss the consequences for the coloring of random graphs. In particular, we argue that in the colorable region the one-step replica symmetry-breaking solution is stable towards more steps of replica symmetry breaking

Elektroosadzanie cyrkonu z roztworu DMSO

nvestigations of voltammetry zirconium deposition from DMSO solution on different substrates were taken. It was found that this is multi-electron process proceeding in a few stages. Moreover, zirconium layers were obtained on titanium, copper stainless steel and nickel. Obtained deposit was in form of white powder, which immediately was oxidized to ZrO2 in the presence of air.W pracy przedstawiono badania woltamperometryczne procesu elektroosadzania cyrkonu z roztworu DMSO na różnych podłożach. Stwierdzono, że jest to procees wieloelektronowy zachodzący w kilku etapach. Ponadto otrzymano warstwy cyrkonu na tytanie, miedzi, stali kwasoodpornej i niklu. Wytworzony osad katodowy miał formę białego proszku, na skutek natychmiastowego utlenienia cyrkonu w kontakcie z powietrzem