A mosaicing approach for the acquisition and representation of 3D painted surfaces for conservation and restoration purposes

This paper describes an approach to the acquisition and representation of information on 3D painted surfaces (usually frescoes) based on the tassellation and mosaicing of the whole surface. The acquisition is carried out using an active vision system specifically designed for these purposes. In this paper, particular emphasis is placed on the mosaicing procedure of the acquired images, which, while conceptually simple, allows one to obtain very good results thanks to the effective exploitation of the features of the acquisition system. A careful qualitative and quantitative analysis of the performances of the system, obtained through tests on real scenes in the laboratory, is also presented.Received: 28 May 2001, Accepted: 8 November 2002, Published online: 18 June 2003 Correspondence to: Paolo GrattoniMassimiliano Spertino: With I.R.I.T.I. under grant N.202.12484 of the Italian Safeguard of Cultural Heritage C.N.R. project.     

Comparison of three restriction endonucleases in IS1245-based RFLP typing of Mycobacterium avium

IS1245-based restriction fragment length polymorphism (RFLP) analysis has been proposed recently for molecular typing of Mycobacterium avium isolates. As there is no standardised method with respect to the optimal restriction enzyme, three restriction endonucleases were tested for analysis of 17 human isolates. The restriction endonucleases, selected on the basis of the physical maps of IS1245 and of the highly homologous IS1311, were BsaAI, that cleaves IS1245, PvuII, that cleaves IS1311, and NruI, that cleaves both IS1245 and IS1311. All the restriction endonucleases yielded polymorphic and complex RFLP patterns. However, BsaAI- and NruI-generated bands were more evenly distributed and easier to detect than PvuII-generated bands, most of which clustered in a narrow zone of the fingerprint. In some cases, DNA digestion with BsaAI or NruI yielded probe-specific restriction fragments of molecular size lower than expected. Moreover, digestion with NruI, which was expected to generate the highest numbers of bands in all the isolates, yielded fewer bands than were obtained with BsaAI or PvuII in 14 and 5 isolates, respectively. These findings might suggest the existence of unidentified IS1245-related insertion element(s) in M. avium isolates. Computer analysis of the IS1245-based RFLP patterns of M. avium isolates showed that the restriction endonucleases were capable, although with minor differences, of defining distinct banding patterns and clusters of identical or highly related isolates, thus confirming IS1245-based RFLP analysis as a useful technique for epidemiological studies.     

MONTE CARLO SIMULATION OF AGGREGATION PROCESSES STRUCTURAL PROPERTIES OF DEPOSITIONAL AGGREGATES

The usefulness of Monte Carlo simulation of aggregation phenomena is discussed and applied in analysis of the structure of particle deposits. The structural properties of depositional aggregates in single and multiparticle regimes are obtained and expressed in terms of fractal geometrical concepts. These properties are related to the Peclet number and to the concentration in the non-aggregate (vapour) phase. The topological properties of the aggregates are obtained from random walk simulation, thus confirming the anomalous properties of these structures, even in the case of multiparticle simulations, i.e. for high values of the concentration in the vapour phase.     

Effect of supply voltage frequency on testing of insulation system

This paper deals with the effect of supply frequency on partial discharge phenomena. Results of measurements performed on artificial and practical test objects are compared with computer simulations based on physical models. This comparative analysis points out and explains the differences in partial discharge phenomena observed in tests performed at different frequencies (from 0.1 to 300 Hz). The consequences associated to the use of different supply frequencies in practical applications are, eventually, outlined.     

Performance and robustness of block constraint preconditioners in finite element coupled consolidation problems

Block constraint preconditioners are a most recent development for the iterative solution to large‐scale, often ill‐conditioned, coupled consolidation problems. A major limitation to their practical use, however, is the somewhat difficult selection of a number of user‐defined parameters (at least 4) in a more or less optimal way. The present paper investigates the robustness of three variants of the block constraint preconditioning in relation to the above parameters. A theoretical analysis of the eigenspectrum of the preconditioned matrix provides relatively simple bounds of the eigenvalues as a function of these parameters. A number of test problems used to validate the theoretical results show that both the mixed constraint preconditioner (MCP) combined with the symmetric quasi‐minimal residual (SQMR) solver and the MCP triangular variant (T‐MCP) combined with the bi‐conjugate gradient stabilized (Bi‐CGSTAB) are efficient and robust tools for the solution to difficult Finite Element‐discretized coupled consolidation problems. Moreover, the practical selection of the user‐defined parameters is relatively easy as a stable behavior is observed for a wide range of fill‐in degree values. The theoretical bounds on the eigenspectrum of the preconditioned matrix may help to suggest the most appropriate parameter combination. Copyright © 2009 John Wiley & Sons, Ltd.     

Modular experimental setup for real‐time analysis of emergent behavior in networks of Chua's circuits

This paper describes the design, realization and use of an analogical, fully reconfigurable experimental setup to analyze the complex dynamics of networks of chaotic circuits. It reports details of the implementation and characterization of the setup, together with representative results, showing its flexibility and potential. The setup allows to choose arbitrarily the coupling strength and interconnection structure among the circuits, the type of link and to select the parameters of the node dynamics. It has a modular structure, and it can accommodate up to 32 nodes interconnected by at most 32 links. The collective dynamics of a relatively large set of different network structures and configurations has been investigated using the setup. Synchronization, pattern formation and other interesting collective phenomena were observed experimentally, their evidence being reported here as an illustration of the potential of the proposed setup. Copyright © 2015 John Wiley & Sons, Ltd.     

Advance on processing of compostable and thermally stable biodegradable polyester blends

Flexible and semiflexible packagings can be manufactured by cast extrusion of plastic sheet and thermoforming of containers. Thermal stability is often required as packaging items after being thermoformed can come in contact with hot food/beverage, especially during hot filling operations. In this framework, the present study deals with the design and manufacturing by thermoforming of plastic containers that are, at the same time, compostable and suitable for high-temperature applications (~100 °C). First, extrusion compounding of Poly(l -lactic acid) (PLLA)-based biodegradable polyester blends was performed. In particular, the effect on the material properties of different types of nucleating agents was investigated. Combinations of micro-lamellar talc, poly(d -lactic acid) (PDLA), ethylene bisstearamide (EBS), and titanium dioxide (TiO₂) were studied. The formulations involving EBS boast the highest crystallinity and the fastest onset of the crystalline phase on sheets produced by cast extrusion. Conversely, the formulations involving TiO₂ feature the lowest degree of crystallinity and the slowest onset of the crystalline phase. Combinations of talc and PDLA exhibit an intermediate behavior. Second, thermoforming of the plastic foils was performed. A very different trend of the crystallization after thermoforming is shown. Indeed, crystallinity is the highest for the formulations involving talc and PDLA, the lowest for the ones containing EBS. In conclusion, the biodegradable polyester blends are found to be suitable for the manufacturing of compostable and thermostable packaging items by cast extrusion and thermoforming. Final crystallization of the material and the resulting thermal stability can be fine-tuned by modulating type and amount of nucleating agents. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48722.     

Optimal selection of soft sensor inputs for batch distillation columns using principal component analysis

In this paper, a novel methodology based on principal component analysis (PCA) is proposed to select the most suitable secondary process variables to be used as soft sensor inputs. In the proposed approach, a matrix is defined that measures the instantaneous sensitivity of each secondary variable to the primary variables to be estimated. The most sensitive secondary variables are then extracted from this matrix by exploiting the properties of PCA, and they are used as input variables for the development of a regression model suitable for on-line implementation.This method has been evaluated by developing a soft sensor that uses temperature measurements and a process regression model to estimate on-line the product compositions for a simulated batch distillation process. The identification of the optimal soft sensor inputs for this case study has been discussed with respect to the definition of the sensitivity matrix, the data sampling interval, the presence of measurement noise, and the size of the input set. The simulation results demonstrate that the proposed approach can effectively identify the size and configuration of the input set that leads to the optimal estimation performance of the soft sensor.     

A Low‐Memory,Straightforward and Fast Bilateral Filter Through Subsampling in Spatial Domain

In this work we present a new algorithm for accelerating the colour bilateral filter based on a subsampling strategy working in the spatial domain. The base idea is to use a suitable subset of samples of the entire kernel in order to obtain a good estimation of the exact filter values. The main advantages of the proposed approach are that it has an excellent trade‐off between visual quality and speed‐up, a very low memory overhead is required and it is straightforward to implement on the GPU allowing real‐time filtering. We show different applications of the proposed filter, in particular efficient cross‐bilateral filtering, real‐time edge‐aware image editing and fast video denoising. We compare our method against the state of the art in terms of image quality, time performance and memory usage.     

How changes affect software entropy: an empirical study

Context Software systems continuously change for various reasons, such as adding new features, fixing bugs, or refactoring. Changes may either increase the source code complexity and disorganization, or help to reducing it. Aim This paper empirically investigates the relationship of source code complexity and disorganization—measured using source code change entropy—with four factors, namely the presence of refactoring activities, the number of developers working on a source code file, the participation of classes in design patterns, and the different kinds of changes occurring on the system, classified in terms of their topics extracted from commit notes. Method We carried out an exploratory study on an interval of the life-time span of four open source systems, namely ArgoUML, Eclipse-JDT, Mozilla, and Samba, with the aim of analyzing the relationship between the source code change entropy and four factors: refactoring activities, number of contributors for a file, participation of classes in design patterns, and change topics. Results The study shows that (i) the change entropy decreases after refactoring, (ii) files changed by a higher number of developers tend to exhibit a higher change entropy than others, (iii) classes participating in certain design patterns exhibit a higher change entropy than others, and (iv) changes related to different topics exhibit different change entropy, for example bug fixings exhibit a limited change entropy while changes introducing new features exhibit a high change entropy. Conclusions Results provided in this paper indicate that the nature of changes (in particular changes related to refactorings), the software design, and the number of active developers are factors related to change entropy. Our findings contribute to understand the software aging phenomenon and are preliminary to identifying better ways to contrast it.