A solving tool for fuzzy quadratic optimal control problems

In this paper we propose an iterative method to solve an optimal control problem, with fuzzy target and constraints. The algorithm is developed in such a way as to satisfy the target function and the constraints. The algorithm can be applied only if a method exists to solve a crisp parametric sub-problem obtained by the original one. This is the case for a quadratic-linear target function with linear constraints, for which some well established solvable methods exist for the crisp associated sub-problem. A numerical test confirmed the good convergence properties.fuzzy, mathematical programming

Performance of soft dielectric laminated composites

This paper contains a thorough investigation of the performance of electrically activated layered soft dielectric composite actuators under plane deformation. Noting that the activation can be induced controlling either the voltage or the surface charge, the overall behaviour of the system is obtained via homogenization at large strains taking either the macroscopic electric field or the macroscopic electric displacement field as independent electrical variable. The performance of a two-phase composite actuator compared to that of the homogeneous case is highlighted for few boundary-value problems and for different values of stiffness and permittivity ratios between constituents being significant for applications, where the soft matrix is reinforced by a relatively small volume fraction of a stiff and high-permittivity phase. For charge-controlled devices, it is shown that some composite layouts admit, on one hand, the occurrence of pull-in/snap-through instabilities that can be exploited to design release-actuated systems, on the other, the possibility of thickening at increasing surface charge density

Modelling fraud detection by attack trees and Choquet integral

Modelling an attack tree is basically a matter of associating a logical ÒndÓand a logical ÒrÓ but in most of real world applications related to fraud management the Ònd/orÓlogic is not adequate to effectively represent the relationship between a parent node and its children, most of all when information about attributes is associated to the nodes and the main problem to solve is how to promulgate attribute values up the tree through recursive aggregation operations occurring at the Ònd/orÓnodes. OWA-based aggregations have been introduced to generalize ÒndÓand ÒrÓoperators starting from the observation that in between the extremes Òor allÓ(and) and Òor anyÓ(or), terms (quantifiers) like ÒeveralÓ ÒostÓ ÒewÓ ÒomeÓ etc. can be introduced to represent the different weights associated to the nodes in the aggregation. The aggregation process taking place at an OWA node depends on the ordered position of the child nodes but it doesnÕ take care of the possible interactions between the nodes. In this paper, we propose to overcome this drawback introducing the Choquet integral whose distinguished feature is to be able to take into account the interaction between nodes. At first, the attack tree is valuated recursively through a bottom-up algorithm whose complexity is linear versus the number of nodes and exponential for every node. Then, the algorithm is extended assuming that the attribute values in the leaves are unimodal LR fuzzy numbers and the calculation of Choquet integral is carried out using the alpha-cuts.Fraud detection; attack tree; ordered weighted averaging (OWA) operator; Choquet integral; fuzzy numbers.

Inconsistency and non-additive Choquet integration in the Analytic Hierarchy Process

We propose to extend the aggregation scheme of Saaty’s AHP, from the stan- dard weighted averaging to the more general Choquet integration. In our model, a measure of inconsistency between criteria is derived from the main pairwise comparison matrix and it is used to construct a non-additive capacity, whose associated Choquet integral reduces to the standard weighted mean in the con- sistency case. In the general inconsistency case, however, the new aggregation scheme based on Choquet integration tends to attenuate (resp. emphasize) the priority values of the criteria with higher (resp. lower) average inconsistency with the remaining criteria.Aggregation Functions, Multiple Criteria Analysis, AHP, Inconsintency, non-additive measures, Choquet integral, and Shapley values.

Investigation of molecular recognition properties of ubiquitin, polyubiquitin and a disease-associated mutant

The small protein ubiquitin acts as a versatile cellular signal that controls a wide range of biological processes. The specificity of ubiquitin signalling is achieved by alternative conjugation signals and interactions with ubiquitin-binding proteins. Despite tremendous advancements in our understanding of ubiquitin function, the molecular details of recognition are still not fully elucidated. In this regard, solution NMR spectroscopy studies show promise to shed light into transient molecular interactions and conformational dynamics governing ubiquitin-mediated signalling. The traditional methods of studying proteins are implemented within dilute solutions with less than 10 g/L of total protein concentration. This low concentration allows to obtain good signals but may not adequately represent a biological environment. One distinctive feature of cellular systems is that the cytoplasm is deeply crowded with macromolecules (50-400 g/L) which affect several protein attributes. Macromolecular crowding can result in non-specific interactions between the protein of interest and the target protein. The broad aim of our study is to understand the effects of macromolecular crowding on ubiquitin recognition. We focused on the ubiquitin-UBA interaction, investigating the perturbations induced by the presence of a synthetic crowding agent in comparison with dilute solution by NMR. We analysed differences in binding affinity, structure and dynamics of the complex dissolved in the different media. Protein-protein interactions are a prime target for drug development and chemical biology research. Mechanisms of protein recognition have been extensively studied for single-domain proteins, but are less well characterized for dynamic multidomain systems. PolyUb represent an important multidomain system that requires recognition by structurally diverse ubiquitin-interacting proteins. Thus, the development of chemical species able to selectively recognize polyUb has become a subject of strong interest. Clearly, nanoparticles (NPs) present several advantages for protein recognition, including a large surface available for interaction. In our project, we aimed to explore NP systems for the development of polyUb-specific receptors. We investigated the binding specificity of chemically diverse NPs towards structurally distinct polyUb. Solution NMR spectroscopy was chosen as the central experimental technique due to its ability to provide site-resolved information on reversibly binding protein-NP pairs. Our results constitute the basis for an improved understanding of polyUb recognition by artificial receptors and for the development of NP-based therapeutic strategies. Given the central role of the Ub network in cellular physiology, misregulation is often associated with diseases, including cancer, immune disorders, and neurodegeneration. Due to a possible participation of the frameshift Ub mutant Ubb+1 in the molecular events leading to neurotoxicity and neurodegeneration in Alzheimer\u2019s disease, there is large interest in elucidating the structural details of this aberrant protein and the consequent functional differences with respect to the wild-type protein. In our work, we investigated structural and dynamic features of Ubb+1 using NMR methods that are particularly suited to explore protein molecules containing flexible domains such as the C-terminal extension of Ubb+1

Optimal energy-harvesting cycles for load-driven dielectric generators in plane strain

The performances of energy harvesting generators based on dielectric elastomers are investigated. The configuration is of a thin dielectric film coated by stretchable electrodes at both sides. The film is first stretched, then charged and subsequently, afterwards it is released, and finally the charge is harvested at a higher electric potential. The amount of energy extracted by this cycle is bounded by the electric breakdown and the ultimate stretch ratio of the film as well as by structural instabilities due to loss of tension. To identify the optimal cycle that complies with these limits we formulate a constraint optimization problem and solve it with a dedicated solver for two typical classes of elastic dielectrics. As anticipated, we find that the performance of the generator depends critically on the ultimate stretch ratio of the film. However, more surprising is our finding of a universal limit on the dielectric strength of the film beyond which the optimal cycle is independent of this parameter. Thus, we reveal that, regardless of how large the dielectric strength of the material is, there is an upper bound on the amount of harvested energy that depends only on the ultimate stretch ratio. We conclude the work with detailed calculations of the optimal cycles for two commercially available elastic dielectrics

Analysis of multilayer electro-active tubes under different constraints

Dielectric elastomers are an emerging class of highly deformable electro-active materials employed for electromechanical transduction technology. For practical applications, the design of such transducers requires a model accounting for insulation of the active membrane, non-perfectly compliant behaviour of the electrodes or interaction of the transducer with a soft actuated body. To this end, a three-layer model, in which the active membrane is embedded between two soft passive layers, can be formulated. In this paper, the theory of nonlinear electro-elasticity for heterogeneous soft dielectrics is used to investigate the electromechanical response of multilayer electro-active tubes---formed either by the active membrane only (single-layer tube) or by the coated active membrane (multilayer tube). Numerical results showing the influence of the mechanical and the geometrical properties of the soft coating layers on the electromechanical response of the active membrane are presented for different constraint conditions.Comment: 30 pages, 7 figure

A miniaturized alpha spectrometer for the calibration of an avalanche-confinement TEPC

The design and development of a recent avalanche-confinement tissue equivalent proportional counter (TEPC) for microdosimetry and nanodosimetry applications required the selection of a proper miniaturized solid state detector (SSD) for detecting alpha particles emitted by a thick removable Cm-244 source embedded in the cylindrical TEPC chamber for characterization and calibration purposes. Since the available cavity for embedding the SSD detector is only 4.2 mm in diameter, no standard devices can be exploited. The selection of the best SSD for this application was based on the following requirements: very low size, proper energy resolution, cheapness. The performances of the finally selected SSD were assessed by exploiting a multi-peak calibration alpha source (Pu-239, Am-241, Cm-244). The measured energy resolution resulted about 25 keV FWHM. The TEPC calibration procedure, which exploits the selected SSD aligned to the built-in Cm-244 alpha source, is described in details

A model for space-time threshold exceedances with an application to extreme rainfall

In extreme value studies models for observations exceeding a fixed high threshold have the advantage of exploiting the available extremal information, while avoiding bias from low values. In the context of space-time data, the challenge is to develop models for threshold exceedances that account for both spatial and temporal dependence. We address this issue through a modelling approach that embeds spatial dependence within a time series formulation. The model allows for different forms of limiting dependence in the spatial and temporal domains as the threshold level increases. In particular, temporal asymptotic independence is assumed, as this is often supported by empirical evidence, especially in environmental applications, while both asymptotic dependence and asymptotic independence are considered for the spatial domain. Inference from the observed exceedances is carried out through a combination of pairwise likelihood and a censoring mechanism. For those model specifications for which direct maximization of the censored pairwise likelihood is unfeasible, we propose an indirect inference procedure which leads to satisfactory results in a simulation study. The approach is applied to a dataset of rainfall amounts recorded over a set of weather stations in the North Brabant province of the Netherlands. The application shows that the range of extremal patterns that the model can cover is wide and that it has a competitive performance with respect to an alternative existing model for space-time threshold exceedances

Application of the Waveform Relaxation Technique to the Co-Simulation of Power Converter Controller and Electrical Circuit Models

In this paper we present the co-simulation of a PID class power converter controller and an electrical circuit by means of the waveform relaxation technique. The simulation of the controller model is characterized by a fixed-time stepping scheme reflecting its digital implementation, whereas a circuit simulation usually employs an adaptive time stepping scheme in order to account for a wide range of time constants within the circuit model. In order to maintain the characteristic of both models as well as to facilitate model replacement, we treat them separately by means of input/output relations and propose an application of a waveform relaxation algorithm. Furthermore, the maximum and minimum number of iterations of the proposed algorithm are mathematically analyzed. The concept of controller/circuit coupling is illustrated by an example of the co-simulation of a PI power converter controller and a model of the main dipole circuit of the Large Hadron Collider