3,637 research outputs found
Defining quantumness via the Jordan product
We propose alternative definitions of classical states and quantumness
witnesses by focusing on the algebra of observables of the system. A central
role will be assumed by the anticommutator of the observables, namely the
Jordan product. This approach turns out to be suitable for generalizations to
infinite dimensional systems. We then show that the whole algebra of
observables can be generated by three elements by repeated application of the
Jordan product
What-if analysis: A visual analytics approach to Information Retrieval evaluation
This paper focuses on the innovative visual analytics approach realized by the Visual Analytics Tool for Experimental Evaluation (VATE2) system, which eases and makes more effective the experimental evaluation process by introducing the what-if analysis. The what-if analysis is aimed at estimating the possible effects of a modification to an Information Retrieval (IR) system, in order to select the most promising fixes before implementing them, thus saving a considerable amount of effort. VATE2 builds on an analytical framework which models the behavior of the systems in order to make estimations, and integrates this analytical framework into a visual part which, via proper interaction and animations, receives input and provides feedback to the user. We conducted an experimental evaluation to assess the numerical performances of the analytical model and a validation of the visual analytics prototype with domain experts. Both the numerical evaluation and the user validation have shown that VATE2 is effective, innovative, and useful
The CLAIRE visual analytics system for analysing IR evaluation data
In this paper, we describe Combinatorial visuaL Analytics system for Information Retrieval Evaluation (CLAIRE), a Visual Analytics (VA) system for exploring and making sense of the performances of a large amount of Information Retrieval (IR) systems, in order to quickly and intuitively grasp which system configurations are preferred, what are the contributions of the different components and how these components interact together
Risk assessment, and carcinogen mutagen for workers potentially exposed in the research laboratories of “Sapienza” University of Rome for Health Surveillance
The following work is meant to represent the evaluation of risk factors for the health of exposed workers, arising from the management of carcinogenic and mutagenic substances, through the use of algorithms. In some places of work as a research laboratory, it is more suitable a theoretical and practical methodology (algorithm) which allows a "timely" exposure assessment. The methodology developed and used is able to determine the level of risk of exposure due to a single agent and / or to more agents. Results obtained by the algorithm, have shown an higher exposure to 1 for formaldehyde (Lcanc = 1.32), while for acrylamide results obtained shows a lower exposure to 1 (Lcanc = 0.528). Although the overall exposure level of studied workers higher value to 1 (Lcanc= 1.848), the Occupational Medicine Centre of "Sapienza" - University of Rome, in agreement with the position taken by the Italian Society of Occupational Medicine and Industrial Hygiene applies health surveillance even in the presence of potential health risk reducing it among the general protection measures the health and safety of workers
Applicazioni di meccanica della frattura all’analisi di stabilitá delle fessure nelle dighe in calcestruzzo
RIASSUNTO. Nel presente lavoro si propone una disamina delle applicazioni di meccanica della frattura
all’analisi del processo fessurativo nelle dighe in calcestruzzo. In tale contesto, ripercorrendo gli studi
pionieristici e i casi di studio affrontati negli anni 1980 e 1990, si illustra nel dettaglio come applicare le
metodologie proprie della meccanica della frattura elastica lineare alla valutazione della stabilitĂ delle fessure e
della loro lunghezza critica. Tale disamina riguarderĂ sia sollecitazioni quasi-statiche, quali il peso proprio e la
pressione idrostatica esercitata dall’acqua, che sollecitazioni sismiche, tema di particolare complessità ed
attualitĂ . Infine, si illustreranno le problematiche relative alla corretta valutazione dei parametri meccanici per
strutture ciclopiche quali le dighe, tenendo propriamente in conto i forti effetti di scala osservati
sperimentalmente.
ABSTRACT. In the present study, a detailed analysis of the applications of fracture mechanics to the
phenomenon of fracture taking place in concrete dams is proposed. In this context, recalling the pioneering
approaches and the case studies proposed in the 1980s and in the 1990s, it will be shown how to apply the
methodologies of linear elastic fracture mechanics to the assessment of crack stability and to the determination
of the corresponding critical crack length. Such an analysis will concern both quasi-static loads, such as the
weight load and the hydraulic pressure, as well as seismic actions, a topic of high complexity and actuality.
Finally, the problems related to the proper evaluation of the mechanical parameters of huge structures such as
dams will be analyzed, taking into account the strong size-scale effects observed in experimental tests
Effetti di scala sulla resistenza a trazione dei materiali
The dissertation analyses the scale effects on the tensile strength of materials. By the term scale effects it is meant the variation in a mechanical property as a function of structural size. In particular, it has been observed by numerous investigators that the nominal tensile strength of many materials decreases with increasing size of the specimen tested.
This phenomenon is more evident in disordered materials, that is, materials that are macroscopically heterogeneous and damaged. On the basis of Weibull's statistical theory and the principles of Linear Elastic Fracture Mechanics, a self-similarity distribution for defect size is presented (Chapter 4). With this distribution the length of the most critical defect is taken to be proportional to the linear size of the specimen. It is shown that the assumption of self-similarity represents the instance of maximum disorder that can be encountered in real materials, and it supplies, in a strength-size bilogarithmic plane, a linear scaling law with an inclination of -1/2, corresponding to the power of the stress singularity envisaged by LEFM.
This formulation contains the fractal concept of self-similarity, even though it is limited to maximum defect dimension.
In order to consider the real nature of the micro-structure of the materials, a more complex fractal model is presented (Chapter 5) in which the property of self-similarity is extended to the entire population of defects. This topological law, based on fractal theory and on the so-called renormalisation procedure, states that in order to obtain a nominal constant strength for the material it is
necessary to refer to surface areas with non integer physical dimensions. For disordered materials, such as for instance concrete and rocks, renormalised tensile strength is given by a force acting on a surface having a fractal dimension lower than 2. The dimensional decrease, always comprised in the [0, 1/2] range, represents self-similar vacancies in the undamaged section associated with the presence of pores, voids, defects, cracks, aggregate and inclusions, and it approaches the 1/2 limit only for extremely brittle and disordered materials, as is assumed, incidentally, in statistical approaches.
As a rule, the scale variation taken into consideration in experimental investigations does not exceed one order of magnitude.
In such circumstances, it is only possible to determine a single tangential inclination in the bilogarithmic diagram.
Only by taking into account scale variations higher than one order of magnitude it proves possible to detect the transition from disordered to ordered conditions, and a continuous transition from -1/2 to zero inclination may be seen to appear. In physical reality, the peak load resistant section can be viewed as multifractal, of dimension 1.5 on small scales and dimension 2 at large scales. This clearly shows a transition from the extreme disorder that is associated with small scales, where a self-similar distribution of Griffith cracks predominates, to the extreme order of large scales, where the disorder of the microstructure is no longer visible, on account of the limited dimensions of the defects and heterogeneities. The assumption of multifractality for the microstructure of the damaged material (Chapter 7) is the basis of the so-called Multifractal Scaling Law (MFSL).
Such law consists of an approximation method which imposes the concavity of the bilogarithmic curve facing upward, which
contradicts Bazant's size effect law (SEL). To verify this scaling law and to determine experimentally the variation in nominal tensile strength and fracture energy, a totally innovative testing set-up has been created, involving the use of three servo-controlled jacks (Chapter 5). The interaction of the three jacks, arranged in L formation, makes it possible to centre instant by instant the resultant of the load with the respect to the undamaged section even in the presence of cracks which make the latter asymmetrical. The main goal of this instrumentation is to determine the parameters of the concrete subjected to uniform tension, eliminating any secondary bending effect which may affect the results and lead to erroneous explanations of the scale effect
Measuring quantumness: from theory to observability in interferometric setups
We investigate the notion of quantumness based on the non-commutativity of
the algebra of observables and introduce a measure of quantumness based on the
mutual incompatibility of quantum states. We show that such a quantity can be
experimentally measured with an interferometric setup and that, when an
arbitrary bipartition of a given composite system is introduced, it detects the
one-way quantum correlations restricted to one of the two subsystems. We
finally show that, by combining only two projective measurements and carrying
out the interference procedure, our measure becomes an efficient universal
witness of quantum discord and non-classical correlations.Comment: 5 pages, 1 figur
Sequent depth ratio of B jumps on smooth and rough beds
A hydraulic B-jump has the toe section located on a positively sloping upstream channel and the roller end on a downstream horizontal channel. This paper analyses the B-jump on a rough bed, such as at the transition from a block ramp to the stilling basin. Laboratory measurements of the sequent depth were carried out using three different channel slopes for the rough bed and a single slope for the smooth bed. A solution useful for estimating the sequent depth ratio in a rectangular channel for different relative roughness and bed slope is proposed and positively tested by the present measurements. This solution can also be used to estimate the sequent depth ratio of classical hydraulic jumps or B-jumps on smooth and rough beds
Stochastic Multi-objective Optimisation of Exoskeleton Structures
In this study, a structural optimisation problem, addressed through a stochastic multi-objective approach, is formulated and solved. The problem deals with the optimal design of exoskeleton structures, conceived as vibration control systems under seismic loading. The exoskeleton structure is assumed to be coupled to an existing primary inner structure for seismic retrofit: the aim is to limit the dynamic response of the primary structure to prevent structural damage. A non-stationary filtered Gaussian white noise stochastic process is taken as the seismic input. Design variables pertain to the mechanical properties (stiffness, damping) of the exoskeleton structure. Two concurrent and competing objective functions are introduced, in order to take into account not only safety performance but also economic cost considerations. The resulting trade-off is solved searching the Pareto front by way of a controlled elitist genetic algorithm, derived from the Non-dominated Sorting Genetic Algorithm-II. Sensitivities of Pareto fronts and Pareto optimal sets to different system parameters are finally investigated by way of a numerical application
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