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11.
Sarv Ahrabi Sima Piazzo Lorenzo Momenzadeh Alireza Scarpiniti Michele Baccarelli Enzo 《The Journal of supercomputing》2022,78(9):12024-12045
The Journal of Supercomputing - We present a probabilistic method for classifying chest computed tomography (CT) scans into COVID-19 and non-COVID-19. To this end, we design and train, in an... 相似文献
12.
Ugo Andreaus Michele Colloca Daniela Iacoviello Marcello Pignataro 《Structural and Multidisciplinary Optimization》2011,43(1):43-59
The objective of this paper was solving the optimization problem of lightweight stiffened structures modelled as a two-dimensional
domain in an efficient computational way. The underlying premise was that mass should be distributed in an efficient way,
so as to use a minimum amount of material to accomplish the mechanical function. This premise was expressed as a global, multi-objective
optimization problem in which stiffness and mass were conflicting objectives. Alternative local evolution rules were implemented
to update mass density or Young’s modulus at each step of the iterative procedure. The solution of the structural optimization
problem was accomplished by a novel automatic procedure consisting of two consecutive stages of control and optimization.
In the first stage of Proportional Integral Derivative (PID) control gains were manually selected whereas in the second stage
the finding of optimal values of control gains, target, and cost indices was allowed. In this study a bone-like material was
adopted and a thin slab was analysed as a sample problem. 相似文献
13.
Michele Barletta Silvio Ranise Luca Vigan�� 《Service Oriented Computing and Applications》2011,5(2):105-137
The specification of distributed service-oriented applications spans several levels of abstraction, e.g., the protocol for
exchanging messages, the set of interface functionalities, the types of the manipulated data, the workflow, the access policy,
etc. Many (even executable) specification languages are available to describe each level in separation. However, these levels
may interact in subtle ways (for example, the control flow may depend on the values of some data variables) so that a precise
abstraction of the application amounts to more than the sum of its per level components. This problem is even more acute in
the design phase when automated analysis techniques may greatly help the difficult task of building “correct” applications
faced by designers. To alleviate this kind of problems, this paper introduces a framework for the formal specification and
automated analysis of distributed service-oriented applications in two levels: one for the workflow and one for the authorization
policies. The former allows one to precisely describe the control and data parts of an application with their mutual dependencies.
The latter focuses on the specification of the criteria for granting or denying third-party applications the possibility to
access shared resources or to execute certain interface functionalities. These levels can be seen as abstractions of one or
of several levels of specification mentioned above. The novelty of our proposal is the possibility to unambiguously specify
the—often subtle—interplay between the workflow and policy levels uniformly in the same framework. Additionally, our framework
allows us to define and investigate verification problems for service-oriented applications (such as executability and invariant
checking) and give sufficient conditions for their decidability. These results are non-trivial because their scope of applicability
goes well beyond the case of finite state spaces allowing for applications manipulating variables ranging over infinite domains.
As proof of concept, we show the suitability and flexibility of our approach on two quite different examples inspired by industrial
case studies. 相似文献
14.
In this paper, we introduce and analyze a modification of the Hermitian and skew-Hermitian splitting iteration method for solving a broad class of complex symmetric linear systems. We show that the modified Hermitian and skew-Hermitian splitting (MHSS) iteration method is unconditionally convergent. Each iteration of this method requires the solution of two linear systems with real symmetric positive definite coefficient matrices. These two systems can be solved inexactly. We consider acceleration of the MHSS iteration by Krylov subspace methods. Numerical experiments on a few model problems are used to illustrate the performance of the new method. 相似文献
15.
We investigate the convergence of the price of anarchy after a limited number of moves in the classical multicast communication game when the underlying communication network is directed. Namely, a subset of nodes of the network are interested in receiving the transmission from a given source node and can share the cost of the used links according to fixed cost sharing methods. At each step, a single receiver is allowed to modify its communication strategy, that is to select a communication path from the source, and assuming a selfish or rational behavior, it will make a best response move, that is it will select a solution yielding the minimum possible payment or shared cost. We determine lower and upper bounds on the price of anarchy, that is the highest possible ratio among the overall cost of the links used by the receivers and the minimum possible cost realizing the required communications, after a limited number of moves under the fundamental Shapley cost sharing method. In particular, assuming that the initial set of connecting paths can be arbitrary, we show an $O(r\sqrt{r})We investigate the convergence of the price of anarchy after a limited number of moves in the classical multicast communication
game when the underlying communication network is directed. Namely, a subset of nodes of the network are interested in receiving
the transmission from a given source node and can share the cost of the used links according to fixed cost sharing methods.
At each step, a single receiver is allowed to modify its communication strategy, that is to select a communication path from
the source, and assuming a selfish or rational behavior, it will make a best response move, that is it will select a solution
yielding the minimum possible payment or shared cost. We determine lower and upper bounds on the price of anarchy, that is
the highest possible ratio among the overall cost of the links used by the receivers and the minimum possible cost realizing
the required communications, after a limited number of moves under the fundamental Shapley cost sharing method. In particular,
assuming that the initial set of connecting paths can be arbitrary, we show an
O(r?r)O(r\sqrt{r})
upper bound on the price of anarchy after 2 rounds, during each of which all the receivers move exactly once, and a matching
lower bound, that we also extend to
W(rk?{r})\Omega(r\sqrt[k]{r})
for any number k≥2 rounds, where r is the number of receivers. Similarly, exactly matching upper and lower bounds equal to r are determined for any number of rounds when starting from the empty state in which no path has been selected. Analogous
results are obtained also with respect to other three natural cost sharing methods considered in the literature, that is the
egalitarian, path-proportional and egalitarian-path proportional ones. Most results are also extended to the undirected case
in which the communication links are bidirectional. 相似文献
16.
Vincenza Carchiolo Michele Malgeri Giuseppe Mangioni Vincenzo Nicosia 《Journal of Parallel and Distributed Computing》2010
Nature is a great source of inspiration for scientists, because natural systems seem to be able to find the best way to solve a given problem by using simple and robust mechanisms. Studying complex natural systems, scientists usually find that simple local dynamics lead to sophisticated macroscopic structures and behaviour. It seems that some kind of local interaction rules naturally allow the system to auto-organize itself as an efficient and robust structure, which can easily solve different tasks. Examples of such complex systems are social networks, where a small set of basic interaction rules leads to a relatively robust and efficient communication structure. In this paper, we present PROSA, a semantic peer-to-peer (P2P) overlay network inspired by social dynamics. The way queries are forwarded and links among peers are established in PROSA resemble the way people ask other people for collaboration, help or information. Behaving as a social network of peers, PROSA naturally evolves to a small world, where all peers can be reached in a fast and efficient way. The underlying algorithm used for query forwarding, based only on local choices, is both reliable and effective: peers sharing similar resources are eventually connected with each other, allowing queries to be successfully answered in a really small amount of time. The resulting emergent structure can guarantee fast responses and good query recall. 相似文献
17.
Given a set of products each with positive discrete demand, and a set of markets selling products at given prices, the traveling purchaser problem (TPP) looks for a tour visiting a subset of markets such that products demand is satisfied at minimum purchasing and traveling costs. In this paper we analyze a dynamic variant of the problem, where quantities may decrease as time goes on. Complete information is assumed on current state of the world, i.e. decision maker knows quantities available for each product in each market at present time and is informed about any consumption event when it occurs. Nevertheless, planner does not have any information on future events. Two groups of heuristics are described and compared. The first group consists of simplified approaches deciding which market to visit next on the basis of some greedy criteria considering only one of the two objective costs. The second one includes heuristics based on a look-ahead approach taking into account both traveling and purchasing costs and inserting some future prediction. Heuristics behavior has been tested on a large set of randomly generated instances under different levels of dynamism. 相似文献
18.
Bruno R. de Araújo Tiago Guerreiro Manuel J. Fonseca Joaquim A. Jorge João M. Pereira Monica Bordegoni Francesco Ferrise Mario Covarrubias Michele Antolini 《Journal of Real-Time Image Processing》2010,5(2):73-90
Currently, the design of aesthetic products is a process that requires a set of activities where digital models and physical
mockups play a key role. Typically, these are modified (and built) several times before reaching the desired design, increasing
the development time and, consequently, the final product cost. In this paper, we present an innovative design environment
for computer-aided design (CAD) surface analysis. Our system relies on a direct visuo-haptic display system, which enables
users to visualize models using a stereoscopic view, and allows the evaluation of sectional curves using touch. Profile curves
are rendered using an haptic device that deforms a plastic strip, thanks to a set of actuators, to reproduce the curvature
of the shape co-located with the virtual model. By touching the strip, users are able to evaluate shape characteristics, such
as curvature or discontinuities (rendered using sound), and to assess the surface quality. We believe that future computer-aided
systems (CAS)/CAD systems based on our approach will contribute in improving the design process at industrial level. Moreover,
these will allow companies to reduce the product development time by reducing the number of physical mockups necessary for
the product design evaluation and by increasing the quality of the final product, allowing a wider exploration and comparative
evaluation of alternatives in the given time. 相似文献
19.
The role of spectral resolution and classifier complexity in the analysis of hyperspectral images of forest areas 总被引:1,自引:0,他引:1
Michele Dalponte Lorenzo Bruzzone Loris Vescovo 《Remote sensing of environment》2009,113(11):2345-2355
Remote sensing hyperspectral sensors are important and powerful instruments for addressing classification problems in complex forest scenarios, as they allow one a detailed characterization of the spectral behavior of the considered information classes. However, the processing of hyperspectral data is particularly complex both from a theoretical viewpoint [e.g. problems related to the Hughes phenomenon (Hughes, 1968) and from a computational perspective. Despite many previous investigations that have been presented in the literature on feature reduction and feature extraction in hyperspectral data, only a few studies have analyzed the role of spectral resolution on the classification accuracy in different application domains. In this paper, we present an empirical study aimed at understanding the relationship among spectral resolution, classifier complexity, and classification accuracy obtained with hyperspectral sensors for the classification of forest areas. We considered two different test sets characterized by images acquired by an AISA Eagle sensor over 126 bands with a spectral resolution of 4.6 nm, and we subsequently degraded its spectral resolution to 9.2, 13.8, 18.4, 23, 27.6, 32.2 and 36.8 nm. A series of classification experiments were carried out with bands at each of the degraded spectral resolutions, and bands selected with a feature selection algorithm at the highest spectral resolution (4.6 nm). The classification experiments were carried out with three different classifiers: Support Vector Machine, Gaussian Maximum Likelihood with Leave-One-Out-Covariance estimator, and Linear Discriminant Analysis. From the experimental results, important conclusions can be made about the choice of the spectral resolution of hyperspectral sensors as applied to forest areas, also in relation to the complexity of the adopted classification methodology. The outcome of these experiments are also applicable in terms of directing the user towards a more efficient use of the current instruments (e.g. programming of the spectral channels to be acquired) and classification techniques in forest applications, as well as in the design of future hyperspectral sensors. 相似文献
20.