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121.
We propose an alternative approach to generate languages by means of P systems: building up an appropriate representation
for a string by means of a corresponding membrane structure and then generating the string by visiting the membrane structure
according to a well-specified strategy. To this aim, we consider P systems with active membranes, allowing membrane creation
or division or duplication and dissolution, where the output of a computation may be obtained either by visiting the tree
associated with the membrane structure, or by following the traces of a specific object, called traveller, or sending out
the objects. For each of these approaches, we provide characterizations of recursively enumerable languages based on P systems
that use different sets of operations for modifying the membrane structure.
Francesco Bernardini: He started his Ph.D. at the University of Sheffield in December 2002 after having previously got a master degree in Computer
Science from the University of Pisa in Italy. His research is dedicated to the study of theoretical aspects of membrane computing
(P systems) and discrete models of biological systems based on P systems.
Marian Gheorghe, Ph.D.: His main research interests are in computational models and their applications to software modelling and testing, formal
specifications of agent based systems, software engineering. He was investigating computational power of various generative
devices (regular, context-free, fully initial; grammar systems; L-systems and variants). He is currently interested in natural
computing (membrane calculus) and biological modelling. 相似文献
122.
A method is presented for checking secure information flow in Java bytecode, assuming a multilevel security policy that assigns security levels to the objects. The method exploits the type‐level abstract interpretation of standard bytecode verification to detect illegal information flows. We define an algorithm transforming the original code into another code in such a way that a typing error detected by the Verifier on the transformed code corresponds to a possible illicit information flow in the original code. We present a prototype tool that implements the method and we show an example of application. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
123.
Focused ion beam (FIB) techniques are among the most important tools for the nanostructuring of surfaces. We used the FIB/SEM (scanning electron microscope) for milling and imaging of digestive gland cells. The aim of our study was to document the interactions of FIB with the surface of the biological sample during FIB investigation, to identify the classes of artifacts, and to test procedures that could induce the quality of FIB milled sections by reducing the artifacts. The digestive gland cells were prepared for conventional SEM. During FIB/SEM operation we induced and enhanced artifacts. The results show that FIB operation on biological tissue affected the area of the sample where ion beam was rastering. We describe the FIB-induced surface major artifacts as a melting-like effect, sweating-like effect, morphological deformations, and gallium (Ga(+)) implantation. The FIB induced surface artifacts caused by incident Ga(+) ions were reduced by the application of a protective platinum strip on the surface exposed to the beam and by a suitable selection of operation protocol. We recommend the same sample preparation methods, FIB protocol for milling and imaging to be used also for other biological samples. 相似文献
124.
Francesco Palmieri Ugo Fiore Aniello Castiglione Alfredo De Santis 《Applied Soft Computing》2013,13(1):615-627
In the last years, the interest in methods and techniques for circumventing the security of the available digital video broadcasting systems is continuously increasing. Digital TV providers are struggling to restrict access to their video contents only to authorized users, by deploying more and more sophisticated conditional access systems. At the state-of-the-art, the most significant menace is the card-sharing activity which exploits a known weakness allowing an authorized subscriber to provide access to digital contents to a potentially large group of unauthorized ones connected over a communication network. This is usually realized by using ad hoc customized devices. Detecting the presence of these illegal systems on a network, by recognizing their related traffic is an issue of primary importance. Unfortunately, to avoid the identification of such traffic, payload obfuscation strategies based on encryption are often used, hindering packet inspection techniques.This paper presents a strategy for the detection of card-sharing traffic, empowered by machine-learning-driven traffic classification techniques and based on the natural capability of wavelet analysis to decompose a traffic time series into several component series associated with particular time and frequency scales and hence allowing its observation at different frequency component levels and with different resolutions. These ideas have been used for the proof-of-concept implementation of an SVM-based binary classification scheme that relies only on time regularities of the traffic and not on the packet contents and hence is immune to payload obfuscation techniques. 相似文献
125.
126.
Development of heterogeneous acid catalysts produced from the carbonization of Miscanthus x giganteus for the esterification of butyric acid to butyl butyrate with n‐butanol 下载免费PDF全文
127.
Daniela dell'Oro Francesco Casamassima Giuseppe Gesualdo Marco Iammarino Paolo Mambelli Valeria Nardelli 《International Journal of Food Science & Technology》2014,49(5):1391-1400
The aim of this study was to develop and validate an efficient analytical method based on gas chromatography/tandem mass spectrometry (GC/MS/MS) for detection and quantification of six pyrethroids residues (Phenothrin, Permethrin, Cyfluthrin, Cypermethrin, Deltamethrin and Fenvalerate) in chicken eggs. The method was based on a preliminary liquid–liquid extraction of albumen‐free yolk samples, followed by a clean‐up by solid‐phase extraction. GC/MS/MS analyses were carried out in the selected reaction monitoring mode. Validation parameters such as specificity, detection capability, decision limit, precision, recovery, stability and ruggedness were determined, resulting in compliance with Decision 2002/657/EC. No complicated apparatus are required; moreover, low volumes of organic solvents and a nonintensive manual labour are required. These low costs and simple procedure, based on rapid and safe operations, may represent a useful tool in the routine analysis of pyrethroids pesticides, in the place of the currently used conventional techniques. 相似文献
128.
Lucia Padalino Marcella Mastromatteo Lucia Lecce Sara Spinelli Francesco Contò Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2014,49(6):1544-1556
The goal of the study was to obtain spaghetti enriched with pea flour with sensory properties close to conventional pasta. To this aim, the study has been organised in two subsequent trials. In the first, the pea flour amount added to the spaghetti was continuously increased until the overall sensory quality reached its threshold value (pea flour concentration = 15%). In fact, the spaghetti samples supplemented with 15% pea flour (15%S‐P) showed less elasticity, unpleasant colour and higher firmness compared to the control sample (CTRL). The second step was aimed to improve the overall sensory quality of the 15%S‐P spaghetti by means of guar gum (GUAR). The sample with GUAR (15%S‐P/GUAR) showed a pleasant colour, odour and taste. Furthermore, the 15%S‐P/GUAR sample recorded a low starch digestibility value (i.e. 54) and a higher soluble fibre content with respect to the 15%S‐P sample. 相似文献
129.
Mathias Bürger Giuseppe Notarstefano Francesco Bullo Frank Allgöwer 《Automatica》2012,48(9):2298-2304
In this paper we propose a novel distributed algorithm to solve degenerate linear programs on asynchronous peer-to-peer networks with distributed information structures. We propose a distributed version of the well-known simplex algorithm for general degenerate linear programs. A network of agents, running our algorithm, will agree on a common optimal solution, even if the optimal solution is not unique, or will determine infeasibility or unboundedness of the problem. We establish how the multi-agent assignment problem can be efficiently solved by means of our distributed simplex algorithm. We provide simulations supporting the conjecture that the completion time scales linearly with the diameter of the communication graph. 相似文献
130.
Francesco Alessandro Cuzzola Manfred Morari 《International journal of control》2013,86(16-17):1293-1301
In this paper we investigate some analysis and control problems for discrete-time hybrid systems in the piece-wise affine form. By using arguments from the dissipativity theory for non-linear systems, we show that H X analysis and synthesis problems can be formulated and solved via linear matrix inequalities by taking into account the switching structure of the considered system. In this paper we address the generalized problem of controlling hybrid systems whose switching structure does not depend only on the state but also on the control input. 相似文献