2004
Journal article
Open Access
A balloon trajectory prediction system
Musso I., Cardillo A., Cosentino O, Memmo A.
Safety requirements and the increase in balloon flight duration make a computerized balloon control system essential. Starting with a global thermodynamic model of a stratospheric balloon (NASA-SINBAD) and 48-h wind forecast data, a flexible system can be built to predict its trajectory. In order to increase the trajectory forecast accuracy, the thermodynamic model of SINBAD, related to infrared radiation and albedo, has been improved. The model and the methodology have been evaluated by comparing the altitude excursion of some already flown zero-pressure balloons, with the altitude excursion computed by SINBAD; meteorological and satellite data (METEOSAT) and meteorological forecast data have been used as input. This system, connected during the mission to the balloon's managing unit, will continuously update the forecast trajectory and will enable real and simulated data to be compared. In this way it will also be possible to simulate the balloon flight trajectory in case of any failures. This paper explains the solution adopted for this system and the application that was carried out for the Italian Space Agency's 2002 summer balloon campaign.Source: Advances in space research 33 (2004): 1722–1726. doi:10.1016/j.asr.2003.07.044
DOI: 10.1016/j.asr.2003.07.044
Metrics:
Musso I., Cardillo A., Cosentino O, Memmo A.
Safety requirements and the increase in balloon flight duration make a computerized balloon control system essential. Starting with a global thermodynamic model of a stratospheric balloon (NASA-SINBAD) and 48-h wind forecast data, a flexible system can be built to predict its trajectory. In order to increase the trajectory forecast accuracy, the thermodynamic model of SINBAD, related to infrared radiation and albedo, has been improved. The model and the methodology have been evaluated by comparing the altitude excursion of some already flown zero-pressure balloons, with the altitude excursion computed by SINBAD; meteorological and satellite data (METEOSAT) and meteorological forecast data have been used as input. This system, connected during the mission to the balloon's managing unit, will continuously update the forecast trajectory and will enable real and simulated data to be compared. In this way it will also be possible to simulate the balloon flight trajectory in case of any failures. This paper explains the solution adopted for this system and the application that was carried out for the Italian Space Agency's 2002 summer balloon campaign.Source: Advances in space research 33 (2004): 1722–1726. doi:10.1016/j.asr.2003.07.044
DOI: 10.1016/j.asr.2003.07.044
Metrics:
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Advances in Space Research 
| Advances in Space Research 
| www.sciencedirect.com | CNR ExploRA
2004
Journal article
Restricted
A framework for reconfiguration-based fault-tolerance in distributed systems
Porcarelli S., Castaldi M., Di Giandomenico F., Bondavalli A., Inverardi P.
Nowadays, many critical services are provided by complex distributed systems which are the result of the reuse and integration of a large number of components. Given their multi-context nature, these components are, in general, not designed to achieve high dependability by themselves, thus their behavior with respect to faults can be the most disparate. Nevertheless, it is paramount for these kinds of systems to beable to survive failures of individual components, as well as attacks and intrusions, although with degraded functionalities. To provide control capabilities over unanticipated events, we focus on fault handling strategies, particularly on system's reconfiguration. The paper describes a framework which provides fault tolerance of components based applications by detecting failures through monitoring and by recovering through system reconfiguration. The framework is based on Lira, an agent distributed infrastructure for remote control and reconfiguration, and a decision maker for selecting suitable new configurations. Lira allows for monitoring and reconfiguration at components and applications level, while decisions are taken following the feedbacks provided by the evaluation of statistical Petri net models.Source: Lecture notes in computer science 3069 (2004): 167–190.
Porcarelli S., Castaldi M., Di Giandomenico F., Bondavalli A., Inverardi P.
Nowadays, many critical services are provided by complex distributed systems which are the result of the reuse and integration of a large number of components. Given their multi-context nature, these components are, in general, not designed to achieve high dependability by themselves, thus their behavior with respect to faults can be the most disparate. Nevertheless, it is paramount for these kinds of systems to beable to survive failures of individual components, as well as attacks and intrusions, although with degraded functionalities. To provide control capabilities over unanticipated events, we focus on fault handling strategies, particularly on system's reconfiguration. The paper describes a framework which provides fault tolerance of components based applications by detecting failures through monitoring and by recovering through system reconfiguration. The framework is based on Lira, an agent distributed infrastructure for remote control and reconfiguration, and a decision maker for selecting suitable new configurations. Lira allows for monitoring and reconfiguration at components and applications level, while decisions are taken following the feedbacks provided by the evaluation of statistical Petri net models.Source: Lecture notes in computer science 3069 (2004): 167–190.
See at:
link.springer.com | CNR ExploRA
2004
Conference article
Unknown
A highly scalable parallel caching system for web search engine results
Fagni T., Perego R., Silvestri F.
This paper discusses the design and implementation of SDC, a new caching strategy aimed to e ciently exploit the locality present in the stream of queries submitted to a Web Search Engine. SDC stores the results of the most frequently submitted queries in a fixed-size read-only portion of the cache, while the queries that cannot be satis ed by the static portion compete for the remaining entries of the cache according to a given cache replacement policy. We experimentally demonstrated the superiority of SDC over purely static and dynamic policies by measuring the hit-ratio achieved on two large query logs by varying cache parameters and the replacement policy used. Finally, we propose an implementation optimized for concurrent accesses, and we accurately evaluate its scalability.Source: Euro-Par 2004 - Parallel Processing, 10th International Euro-Par Conference, pp. 347–354, Pisa, Italy, 31 August - 3 September 2004
Fagni T., Perego R., Silvestri F.
This paper discusses the design and implementation of SDC, a new caching strategy aimed to e ciently exploit the locality present in the stream of queries submitted to a Web Search Engine. SDC stores the results of the most frequently submitted queries in a fixed-size read-only portion of the cache, while the queries that cannot be satis ed by the static portion compete for the remaining entries of the cache according to a given cache replacement policy. We experimentally demonstrated the superiority of SDC over purely static and dynamic policies by measuring the hit-ratio achieved on two large query logs by varying cache parameters and the replacement policy used. Finally, we propose an implementation optimized for concurrent accesses, and we accurately evaluate its scalability.Source: Euro-Par 2004 - Parallel Processing, 10th International Euro-Par Conference, pp. 347–354, Pisa, Italy, 31 August - 3 September 2004
See at: CNR ExploRA
2004
Journal article
Unknown
A methodology for the derivation and verification of use cases for product lines
Fantechi A., Gnesi S., Lami G., Nesti E.
In this paper, we present a methodology to express, in a formal way, the requirements of products belonging to a product line. We relied on a formalism allowing the representation of variabilities at the family level and the instantiation of them in order to move to the requirements of a single product. The proposed methodology also allows the formalization of the family constraints to be taken into account for the construction of the products belonging to it, along with the verification of the compliance to those constraints of a single product requirements document. This approach is promising due to its simplicity and effectiveness for being supported by automatic tools.Source: Lecture notes in computer science 3154 (2004): 255–265.
Fantechi A., Gnesi S., Lami G., Nesti E.
In this paper, we present a methodology to express, in a formal way, the requirements of products belonging to a product line. We relied on a formalism allowing the representation of variabilities at the family level and the instantiation of them in order to move to the requirements of a single product. The proposed methodology also allows the formalization of the family constraints to be taken into account for the construction of the products belonging to it, along with the verification of the compliance to those constraints of a single product requirements document. This approach is promising due to its simplicity and effectiveness for being supported by automatic tools.Source: Lecture notes in computer science 3154 (2004): 255–265.
See at: CNR ExploRA
2004
Journal article
Restricted
A numerical method for the limit analysis of masonry structures
Degl'Innocenti S., Padovani C.
The paper presents a numerical method for the limit analysis of structures made of a rigid no-tension material. Firstly, we formulate the constrained minimum problem resulting from the application of the kinematic theorem, which characterizes the collapse multiplier as the minimum of all kinematically admissible multipliers. Subsequently, by using the finite element method, we derive the corresponding discrete minimum problem in which the objective function is linear and the inequality constraints are linear as well as quadratic. The method is then applied to some examples for which the collapse multiplier and a collapse mechanism are explicitly known. Lastly, the solution to the minimum problem calculated via numerical codes for quadratic programming problems, is compared to the exact solution.Source: Structural Engineering and Mechanics 18 (2004): 1–20. doi:10.12989/sem.2004.18.1.001
DOI: 10.12989/sem.2004.18.1.001
Metrics:
Degl'Innocenti S., Padovani C.
The paper presents a numerical method for the limit analysis of structures made of a rigid no-tension material. Firstly, we formulate the constrained minimum problem resulting from the application of the kinematic theorem, which characterizes the collapse multiplier as the minimum of all kinematically admissible multipliers. Subsequently, by using the finite element method, we derive the corresponding discrete minimum problem in which the objective function is linear and the inequality constraints are linear as well as quadratic. The method is then applied to some examples for which the collapse multiplier and a collapse mechanism are explicitly known. Lastly, the solution to the minimum problem calculated via numerical codes for quadratic programming problems, is compared to the exact solution.Source: Structural Engineering and Mechanics 18 (2004): 1–20. doi:10.12989/sem.2004.18.1.001
DOI: 10.12989/sem.2004.18.1.001
Metrics:
See at:
STRUCTURAL ENGINEERING AND MECHANICS | koreascience.or.kr | www.scopus.com | CNR ExploRA
2004
Journal article
Restricted
A signature-based Approach for efficient relationship search on XML data collections
Amato G., Debole F., Rabitti F., Savino P., Zezula P.
We study the problem of finding relevant relationships among user defined nodes of XML documents. We define a language that determines the nodes as results of XPath expressions. The expressions are structured in a conjunctive normal form and the relationships among nodes qualifying in different conjuncts are determined as tree twigs of the searched XML documents. The query execution is supported by an auxiliary index structure called the tree signature. We have implemented a prototype system that supports this kind of searching and we have conducted numerous experiments on XML data collections. We have found the query execution very efficient, thus suitable for on-line processing. We also demonstrate the superiority of our system with respect to a previous, rather restricted, approach of finding the lowest common ancestor of pairs of XML nodes.Source: Lecture notes in computer science 3186 (2004): 82–96. doi:10.1007/978-3-540-30081-6_7
DOI: 10.1007/978-3-540-30081-6_7
Metrics:
Amato G., Debole F., Rabitti F., Savino P., Zezula P.
We study the problem of finding relevant relationships among user defined nodes of XML documents. We define a language that determines the nodes as results of XPath expressions. The expressions are structured in a conjunctive normal form and the relationships among nodes qualifying in different conjuncts are determined as tree twigs of the searched XML documents. The query execution is supported by an auxiliary index structure called the tree signature. We have implemented a prototype system that supports this kind of searching and we have conducted numerous experiments on XML data collections. We have found the query execution very efficient, thus suitable for on-line processing. We also demonstrate the superiority of our system with respect to a previous, rather restricted, approach of finding the lowest common ancestor of pairs of XML nodes.Source: Lecture notes in computer science 3186 (2004): 82–96. doi:10.1007/978-3-540-30081-6_7
DOI: 10.1007/978-3-540-30081-6_7
Metrics:
See at:
doi.org | www.springerlink.com | CNR ExploRA
2004
Conference article
Unknown
A tool to execute ASSIST programs on globus-based grids
Baraglia R., Laforenza D., Tonellotto N.
This article describes ASSISTCONF, a graphical user interface designed to execute ASSIST applications on Globus-based Grids. ASSIST (A Software development System based upon Integrated Skeleton Technology) is a new programming environment for the development of parallel and distributed high-performance applications. The main goals of ASSIST are allowing high-level programmability and software productivity for complex multidisciplinary applications, and performance portability across different platforms, including homogeneous parallel machines and cluster/Beowulf systems, heterogeneous clusters, and computational Grids. ASSISTCONF hides to the programmer the structure of the grid used and integrates the ASSIST Run Time System with the Globus middleware. The first version of ASSISTCONF was designed to manually configure an ASSIST application and to establish a mapping between the application components and the machines selected for its execution on the Grid. The new ASSISTCONF functionalities, such as authentication and execution authorization on the resources selected in the application mapping phase, and deployment on the selected resources of the ASSIST Run Time Support, the executable application components, and the application input data, allow the semi-automatic execution of an ASSIST application on a such environment.Source: 5th International Conference on Parallel Processing and Applied, pp. 1075–1082, Czestochowa, Poland, 07-10/0972003
Baraglia R., Laforenza D., Tonellotto N.
This article describes ASSISTCONF, a graphical user interface designed to execute ASSIST applications on Globus-based Grids. ASSIST (A Software development System based upon Integrated Skeleton Technology) is a new programming environment for the development of parallel and distributed high-performance applications. The main goals of ASSIST are allowing high-level programmability and software productivity for complex multidisciplinary applications, and performance portability across different platforms, including homogeneous parallel machines and cluster/Beowulf systems, heterogeneous clusters, and computational Grids. ASSISTCONF hides to the programmer the structure of the grid used and integrates the ASSIST Run Time System with the Globus middleware. The first version of ASSISTCONF was designed to manually configure an ASSIST application and to establish a mapping between the application components and the machines selected for its execution on the Grid. The new ASSISTCONF functionalities, such as authentication and execution authorization on the resources selected in the application mapping phase, and deployment on the selected resources of the ASSIST Run Time Support, the executable application components, and the application input data, allow the semi-automatic execution of an ASSIST application on a such environment.Source: 5th International Conference on Parallel Processing and Applied, pp. 1075–1082, Czestochowa, Poland, 07-10/0972003
See at: CNR ExploRA
2004
Conference article
Unknown
A unifying framework for flexible information access in taxonomy-based sources
Tzitzikas Y., Meghini C., Spyratos N.
A taxonomy-based source consists of a taxonomy and a database storing objects that are indexed in terms of the taxonomy. For this kind of sources, we describe a flexible interaction scheme that allows users to retrieve the objects of interest without having to be familiar with the terms of the taxonomy or with the supported query language. Specifically we describe an interaction manager whose functionality unifies several well-known interaction schemes including query by example, answer enlargement/reduction, query relaxation/ restriction, index relaxation/contraction, feedback and adaptation mechanisms.Source: International Conference On Flexible Query Answering Systems (FQAS), pp. 161–174, Lyon, France, June 2004
Tzitzikas Y., Meghini C., Spyratos N.
A taxonomy-based source consists of a taxonomy and a database storing objects that are indexed in terms of the taxonomy. For this kind of sources, we describe a flexible interaction scheme that allows users to retrieve the objects of interest without having to be familiar with the terms of the taxonomy or with the supported query language. Specifically we describe an interaction manager whose functionality unifies several well-known interaction schemes including query by example, answer enlargement/reduction, query relaxation/ restriction, index relaxation/contraction, feedback and adaptation mechanisms.Source: International Conference On Flexible Query Answering Systems (FQAS), pp. 161–174, Lyon, France, June 2004
See at: CNR ExploRA
2004
Conference article
Unknown
Accelerating apache farms through Ad-HOC distributed scalable object repository
Aldinucci M., Torquati M.
We present hoc: a fast, scalable object repository providing programmers with a general storage module. hoc may be used to implement DSMs as well as distributed cache subsystems. Hoc is composed of a set of hot-pluggable cooperating processes that may sustain a close to optimal network traffic rate. We designed an hoc-based Web cache that extends the Apache Web server and remarkably improves Apache farms performances with no modification to the Apache core code.Source: EuroPar2004: Parallel and Distributed Computing, pp. 596–605, Pisa, Italy, September 2004
Aldinucci M., Torquati M.
We present hoc: a fast, scalable object repository providing programmers with a general storage module. hoc may be used to implement DSMs as well as distributed cache subsystems. Hoc is composed of a set of hot-pluggable cooperating processes that may sustain a close to optimal network traffic rate. We designed an hoc-based Web cache that extends the Apache Web server and remarkably improves Apache farms performances with no modification to the Apache core code.Source: EuroPar2004: Parallel and Distributed Computing, pp. 596–605, Pisa, Italy, September 2004
See at: CNR ExploRA
2004
Journal article
Restricted
Adaptive tetraPuzzles: efficient out-of-core construction and visualization of gigantic multiresolution polygonal models
Cignoni P., Ganovelli F., Gobetti E., Marton F., Ponchio F., Scopigno R.
We describe an efficient technique for out-of-core construction and accurate view-dependent visualization of very large surface models. The method uses a regular conformal hierarchy of tetrahedra to spatially partition the model. Each tetrahedral cell contains a precomputed simplified version of the original model, represented using cache coherent indexed strips for fast rendering. The representation is constructed during a fine-to-coarse simplification of the surface contained in diamonds (sets of tetrahedral cells sharing their longest edge). The construction preprocess operates out-of-core and parallelizes nicely. Appropriate boundary constraints are introduced in the simplification to ensure that all conforming selective subdivisions of the tetrahedron hierarchy lead to correctly matching surface patches. For each frame at runtime, the hierarchy is traversed coarse-to-fine to select diamonds of the appropriate resolution given the view parameters. The resulting system can interatively render high quality views of out-of-core models of hundreds of millions of triangles at over 40Hz (or 70M triangles/s) on current commodity graphics platformsSource: ACM transactions on graphics 23 (2004): 796–803. doi:10.1145/1015706.1015802
DOI: 10.1145/1015706.1015802
DOI: 10.1145/1186562.1015802
DOI: 10.1145/1508044.1508077
Metrics:
Cignoni P., Ganovelli F., Gobetti E., Marton F., Ponchio F., Scopigno R.
We describe an efficient technique for out-of-core construction and accurate view-dependent visualization of very large surface models. The method uses a regular conformal hierarchy of tetrahedra to spatially partition the model. Each tetrahedral cell contains a precomputed simplified version of the original model, represented using cache coherent indexed strips for fast rendering. The representation is constructed during a fine-to-coarse simplification of the surface contained in diamonds (sets of tetrahedral cells sharing their longest edge). The construction preprocess operates out-of-core and parallelizes nicely. Appropriate boundary constraints are introduced in the simplification to ensure that all conforming selective subdivisions of the tetrahedron hierarchy lead to correctly matching surface patches. For each frame at runtime, the hierarchy is traversed coarse-to-fine to select diamonds of the appropriate resolution given the view parameters. The resulting system can interatively render high quality views of out-of-core models of hundreds of millions of triangles at over 40Hz (or 70M triangles/s) on current commodity graphics platformsSource: ACM transactions on graphics 23 (2004): 796–803. doi:10.1145/1015706.1015802
DOI: 10.1145/1015706.1015802
DOI: 10.1145/1186562.1015802
DOI: 10.1145/1508044.1508077
Metrics:
See at:
dl.acm.org | ACM Transactions on Graphics | doi.org | doi.org | www.scopus.com | CNR ExploRA
2004
Journal article
Open Access
Allocating servers in infostations for bounded simultaneous requests
Bertossi A. A., Pinotti M. C., Rizzi R., Gupta P.
The Server Allocation with Bounded Simultaneous Requests problem arises in isolated infostations, where mobile users going through the coverage area require immediate high-bit rate communications such as web surfing, file transferring, voice messaging, email and fax. Given a set of service requests, each characterized by a temporal interval and a category, an integer $k$, and an integer $h_c$ for each category $c$, the problem consists in assigning a server to each request in such a way that at most $k$ mutually simultaneous requests are assigned to the same server at the same time, out of which at most $h_c$ are of category $c$, and the minimum number of servers is used. Since this problem is computationally intractable, a $2$-approximation on-line algorithm is exhibited which asymptotically gives a $left(2-frac{h}{k}right)$-approximation, where $h = min {h_c}$. Generalizations of the problem are considered, where each request $r$ is also characterized by a bandwidth rate $w_r$, and the sum of the bandwidth rates of the simultaneous requests assigned to the same server at the same time is bounded, and whereeach request is characterized also by a gender bandwidth. Such generalizations contain Bin-Packing, Multiprocessor Task Scheduling, and Interval Graph Coloring as special cases, and they admit on-line algorithms providing constant approximations.Source: Journal of parallel and distributed computing (Print) 64 (2004): 1113–1126. doi:10.1016/j.jpdc.2004.06.003
DOI: 10.1016/j.jpdc.2004.06.003
Metrics:
Bertossi A. A., Pinotti M. C., Rizzi R., Gupta P.
The Server Allocation with Bounded Simultaneous Requests problem arises in isolated infostations, where mobile users going through the coverage area require immediate high-bit rate communications such as web surfing, file transferring, voice messaging, email and fax. Given a set of service requests, each characterized by a temporal interval and a category, an integer $k$, and an integer $h_c$ for each category $c$, the problem consists in assigning a server to each request in such a way that at most $k$ mutually simultaneous requests are assigned to the same server at the same time, out of which at most $h_c$ are of category $c$, and the minimum number of servers is used. Since this problem is computationally intractable, a $2$-approximation on-line algorithm is exhibited which asymptotically gives a $left(2-frac{h}{k}right)$-approximation, where $h = min {h_c}$. Generalizations of the problem are considered, where each request $r$ is also characterized by a bandwidth rate $w_r$, and the sum of the bandwidth rates of the simultaneous requests assigned to the same server at the same time is bounded, and whereeach request is characterized also by a gender bandwidth. Such generalizations contain Bin-Packing, Multiprocessor Task Scheduling, and Interval Graph Coloring as special cases, and they admit on-line algorithms providing constant approximations.Source: Journal of parallel and distributed computing (Print) 64 (2004): 1113–1126. doi:10.1016/j.jpdc.2004.06.003
DOI: 10.1016/j.jpdc.2004.06.003
Metrics:
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Journal of Parallel and Distributed Computing | Journal of Parallel and Distributed Computing | Archivio istituzionale della ricerca - Alma Mater Studiorum Università di Bologna | www.sciencedirect.com | CNR ExploRA
2004
Journal article
Open Access
An IR image processing approach for characterising combustion instability
Chimenti M., Di Natali C., Mariotti G., Paganini E., Pieri G., Salvetti O.
"The paper presents a first approach to the analysis of the dynamic behaviour of a premixed hydrogen/air jet flame using near-IR imaging. In this kind of flames spectral lines are observed in the infrared, visible, and ultraviolet regions; emissions of visible light are however not so strong as in other wavelengths, especially in the near-infrared and infrared portions of the spectrum. Using a video camera, coupled with an optical filter, it is possible to capture images of the flame in a burner and then acquire sequences of images of the near-infrared emission during the combustion process. In this work, carried out in the frame of a collaboration between ENEL Produzione - Ricerca and ISTI - CNR, we propose a method suitable to process and analyse maps of near-infrared emissions in order to characterize the flame morphology and compute geometric and densitometric features useful to describe the combustion dynamics. The map of the emissions presents in some cases different unconnected sources with interesting distribution. In our analysis, we considered two different layers: the single images, as a distribution of near-IR emission, and the complete sequence of images in a dynamical evolution of the whole process."Source: Infrared physics & technology 46 (2004): 41–47. doi:10.1016/j.infrared.2004.03.007
DOI: 10.1016/j.infrared.2004.03.007
Metrics:
Chimenti M., Di Natali C., Mariotti G., Paganini E., Pieri G., Salvetti O.
"The paper presents a first approach to the analysis of the dynamic behaviour of a premixed hydrogen/air jet flame using near-IR imaging. In this kind of flames spectral lines are observed in the infrared, visible, and ultraviolet regions; emissions of visible light are however not so strong as in other wavelengths, especially in the near-infrared and infrared portions of the spectrum. Using a video camera, coupled with an optical filter, it is possible to capture images of the flame in a burner and then acquire sequences of images of the near-infrared emission during the combustion process. In this work, carried out in the frame of a collaboration between ENEL Produzione - Ricerca and ISTI - CNR, we propose a method suitable to process and analyse maps of near-infrared emissions in order to characterize the flame morphology and compute geometric and densitometric features useful to describe the combustion dynamics. The map of the emissions presents in some cases different unconnected sources with interesting distribution. In our analysis, we considered two different layers: the single images, as a distribution of near-IR emission, and the complete sequence of images in a dynamical evolution of the whole process."Source: Infrared physics & technology 46 (2004): 41–47. doi:10.1016/j.infrared.2004.03.007
DOI: 10.1016/j.infrared.2004.03.007
Metrics:
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ISTI Repository | Infrared Physics & Technology | www.sciencedirect.com | CNR ExploRA
2004
Journal article
Restricted
An experimental study on the quality of service of video encoded sequences over an emulated rain-faded satellite channel
Celandroni N., Davoli F., Ferro E., Vignola S., Zappatore S., Zinicola A.
Video coding techniques, widely used in videoconferencing and streaming applications over the Internet, may face degradation in performance when traversing satellite channels. The aim of the present paper is to provide objective measurements of the quality of video encoded sequences for two of the most popular video coders in this setting (namely, H.261 and MPEG-2), after transmission over faded satellite channels. In particular, the emphasis is on the Ka band, which is becoming an attractive alternative for commercial applications, but is more prone to quality degradation than the currently widely used Ku band. In order to test the behaviour of the coders in repeatable experimental conditions and over different data link platforms, two transmission chains have been implemented in the laboratory, by careful emulation of the required environment. The data link layer has been based on HDLC-like and DVB protocols, respectively. The experiments have been performed in the presence of additive white Gaussian noise (AWGN), and by using fading patterns derived by real world data. The results obtained highlight some often neglected aspects in the behaviour of the coders under examination, both in relation to their comparative performance and to their adaptability to different underlying data link protocols.Source: IEEE journal on selected areas in communications (Print) 22 (2004): 229–237. doi:10.1109/JSAC.2003.819971
DOI: 10.1109/jsac.2003.819971
Metrics:
Celandroni N., Davoli F., Ferro E., Vignola S., Zappatore S., Zinicola A.
Video coding techniques, widely used in videoconferencing and streaming applications over the Internet, may face degradation in performance when traversing satellite channels. The aim of the present paper is to provide objective measurements of the quality of video encoded sequences for two of the most popular video coders in this setting (namely, H.261 and MPEG-2), after transmission over faded satellite channels. In particular, the emphasis is on the Ka band, which is becoming an attractive alternative for commercial applications, but is more prone to quality degradation than the currently widely used Ku band. In order to test the behaviour of the coders in repeatable experimental conditions and over different data link platforms, two transmission chains have been implemented in the laboratory, by careful emulation of the required environment. The data link layer has been based on HDLC-like and DVB protocols, respectively. The experiments have been performed in the presence of additive white Gaussian noise (AWGN), and by using fading patterns derived by real world data. The results obtained highlight some often neglected aspects in the behaviour of the coders under examination, both in relation to their comparative performance and to their adaptability to different underlying data link protocols.Source: IEEE journal on selected areas in communications (Print) 22 (2004): 229–237. doi:10.1109/JSAC.2003.819971
DOI: 10.1109/jsac.2003.819971
Metrics:
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IEEE Journal on Selected Areas in Communications | ieeexplore.ieee.org | CNR ExploRA
2004
Conference article
Unknown
An extended maximum likelihood approach for the robust blind separation of autocorrelated images from noisy mixtures
Gerace I., Cricco D., Tonazzini A.
In this paper we consider the problem of separating autocorrelated source images from linear mixtures with unknown coefficients, in presence of even significant noise. Assuming the statistical independence of the sources, we formulate the problem in a Bayesian estimation framework, and describe local correlation within the individual source images through the use of suitable Gibbs priors, accounting also for well-behaved edges in the images. Based on an extension of the Maximum Likelihood approach to ICA, we derive an algorithm for recovering the mixing matrix that makes the estimated sources fit the known properties of the original sources. The preliminary experimental results on synthetic mixtures showed that a significant robustness against noise, both stationary and non-stationary, can be achieved even by using generic autocorrelation models.Source: ICA 2004 - Independent Component Analysis and Blind Signal Separation: Fifth International Conference, pp. 954–961, Granada, Spain, 22-24 September
Gerace I., Cricco D., Tonazzini A.
In this paper we consider the problem of separating autocorrelated source images from linear mixtures with unknown coefficients, in presence of even significant noise. Assuming the statistical independence of the sources, we formulate the problem in a Bayesian estimation framework, and describe local correlation within the individual source images through the use of suitable Gibbs priors, accounting also for well-behaved edges in the images. Based on an extension of the Maximum Likelihood approach to ICA, we derive an algorithm for recovering the mixing matrix that makes the estimated sources fit the known properties of the original sources. The preliminary experimental results on synthetic mixtures showed that a significant robustness against noise, both stationary and non-stationary, can be achieved even by using generic autocorrelation models.Source: ICA 2004 - Independent Component Analysis and Blind Signal Separation: Fifth International Conference, pp. 954–961, Granada, Spain, 22-24 September
See at: CNR ExploRA
2004
Conference article
Unknown
Astrophysical image separation using particle filters
Costagli M., Kuruoglu E. E., Ahmed A.
In this work, we will confront the problem of source separation in the field of astrophysics, where the contributions of various Galactic and extra-Galactic components need to be separated from a set of observed noisy mixtures. Most of the previous work on the problem perform blind source separation, assume noiseless models, and in the few cases when noise is taken into account assume Gaussianity and space-invariance. However, in the real scenario both the sources and the noise are space-varying. In this work, we present a novel technique, namely particle filtering, for the non-blind (Bayesian) solution of the source separation problem, in case of non-stationary sources and noise, by exploiting available a-priori information.Source: International Conference on Independent Component Analysis and Blind Signal Separation (ICA), pp. 930–937, Granada, Spagna, 22-24 September 2004
Costagli M., Kuruoglu E. E., Ahmed A.
In this work, we will confront the problem of source separation in the field of astrophysics, where the contributions of various Galactic and extra-Galactic components need to be separated from a set of observed noisy mixtures. Most of the previous work on the problem perform blind source separation, assume noiseless models, and in the few cases when noise is taken into account assume Gaussianity and space-invariance. However, in the real scenario both the sources and the noise are space-varying. In this work, we present a novel technique, namely particle filtering, for the non-blind (Bayesian) solution of the source separation problem, in case of non-stationary sources and noise, by exploiting available a-priori information.Source: International Conference on Independent Component Analysis and Blind Signal Separation (ICA), pp. 930–937, Granada, Spagna, 22-24 September 2004
See at: CNR ExploRA
2004
Journal article
Restricted
BeppoSAX equatorial uncontrolled re-entry
Portelli C., Salotti L., Anselmo L., Lips T., Tramutola A.
The X-ray astronomy satellite BeppoSAX (Satellite per Astronomia X, ''Beppo'' in honor of Giuseppe Occhialini), is a project of the Italian Space Agency (ASI) with the participation of the Netherlands Agency for Aerospace Programs (NIVR). BeppoSAX was launched by an Atlas G-Centaur directly into a circular 600 km orbit at 3.9 inclination on April 30, 1996. The satellite is a three axis stabilized spacecraft with a total mass of about 1400 kg and main dimensions in flight configuration of about 2450 mm 8980 mm 3650 mm. The current (September 21, 2002) flight altitude is about 435 km and its uncontrolled re-entry is predicted late in 2002, or in 2003, with 26 kg of hydrazine on board that could not be vented or used for controlled re-entry due to the gyro package total failure. Due to the relatively high mass of BeppoSAX, it must be expected that parts of the satellite will survive the re-entry into the Earth atmosphere. The Italian Space Agency has committed a study to analyse of the destructive phase of the uncontrolled atmospheric re-entry by means of a dedicated European software tool (SCARAB). The expected outputs will be used in order to determine how much of the spacecraft and how many fragments of it will reach the ground on the equatorial earth zone. This paper will address the peculiarities of the spacecrafts initial status, its risks at end of life, and the SCARAB modeling as well as its six dimension flight dynamics re-entry analysis results also in terms of the destruction history tree. Consideration will be made of the ground dispersion and casualty area due to the very restricted equatorial zone impacted.Source: Advances in space research 34 (2004): 1029–1037. doi:10.1016/j.asr.2003.11.011
DOI: 10.1016/j.asr.2003.11.011
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Portelli C., Salotti L., Anselmo L., Lips T., Tramutola A.
The X-ray astronomy satellite BeppoSAX (Satellite per Astronomia X, ''Beppo'' in honor of Giuseppe Occhialini), is a project of the Italian Space Agency (ASI) with the participation of the Netherlands Agency for Aerospace Programs (NIVR). BeppoSAX was launched by an Atlas G-Centaur directly into a circular 600 km orbit at 3.9 inclination on April 30, 1996. The satellite is a three axis stabilized spacecraft with a total mass of about 1400 kg and main dimensions in flight configuration of about 2450 mm 8980 mm 3650 mm. The current (September 21, 2002) flight altitude is about 435 km and its uncontrolled re-entry is predicted late in 2002, or in 2003, with 26 kg of hydrazine on board that could not be vented or used for controlled re-entry due to the gyro package total failure. Due to the relatively high mass of BeppoSAX, it must be expected that parts of the satellite will survive the re-entry into the Earth atmosphere. The Italian Space Agency has committed a study to analyse of the destructive phase of the uncontrolled atmospheric re-entry by means of a dedicated European software tool (SCARAB). The expected outputs will be used in order to determine how much of the spacecraft and how many fragments of it will reach the ground on the equatorial earth zone. This paper will address the peculiarities of the spacecrafts initial status, its risks at end of life, and the SCARAB modeling as well as its six dimension flight dynamics re-entry analysis results also in terms of the destruction history tree. Consideration will be made of the ground dispersion and casualty area due to the very restricted equatorial zone impacted.Source: Advances in space research 34 (2004): 1029–1037. doi:10.1016/j.asr.2003.11.011
DOI: 10.1016/j.asr.2003.11.011
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Advances in Space Research | CNR ExploRA
2004
Conference article
Unknown
Bleed-through removal from degraded documents using a color decorrelation method
Tonazzini A., Salerno E., Mochi M., Bedini L.
A color decorrelation strategy to improve the human or automatic readability of degraded documents is presented. The particular degradation that is considered here is bleed-through, that is, a pattern that interferes with the text to be read due to seeping of ink from the reverse side of the document. A simplified linear model for this degradation is introduced to permit the application of very fast decorrelation techniques to the RGB components of the color data images, and to compare this strategy to the independent component analysis approach. Some examples from an extensive experimentation with real ancient documents are described, and the possibility to further improve the restoration performance by using hyperspectral/multispectral data is envisaged.Source: International Workshop on Document Analysis Systems, pp. 229–240, Florence, Italy, 8-10 September
Tonazzini A., Salerno E., Mochi M., Bedini L.
A color decorrelation strategy to improve the human or automatic readability of degraded documents is presented. The particular degradation that is considered here is bleed-through, that is, a pattern that interferes with the text to be read due to seeping of ink from the reverse side of the document. A simplified linear model for this degradation is introduced to permit the application of very fast decorrelation techniques to the RGB components of the color data images, and to compare this strategy to the independent component analysis approach. Some examples from an extensive experimentation with real ancient documents are described, and the possibility to further improve the restoration performance by using hyperspectral/multispectral data is envisaged.Source: International Workshop on Document Analysis Systems, pp. 229–240, Florence, Italy, 8-10 September
See at: CNR ExploRA
2004
Conference article
Unknown
Blind source separation techniques for detecting hidden texts and textures in document images
Tonazzini A., Salerno E., Mochi M., Bedini L.
Blind Source Separation techniques, based both on Independent Component Analysis and on second order statistics, are presented and compared for extracting partially hidden texts and textures in document images. Barely perceivable features may occur, for instance, in ancient documents previously erased and then re-written (palimpsests), or for transparency or seeping of ink from the reverse side, or from watermarks in the paper. Detecting these features can be of great importance to scholars and historians. In our approach, the document is modeled as the superposition of a number of source patterns, and a simplified linear mixture model is introduced for describing the relationship between these sources and multispectral views of the document itself. The problem of detecting the patterns that are barely perceivable in the visible color image is thus formulated as the one of separating the various patterns in the mixtures. Some examples from an extensive experimentation with real ancient documents are shown and commented.Source: International Conference on Image Analysis and Recognition, pp. 241–248, Porto, Portugal, September
Tonazzini A., Salerno E., Mochi M., Bedini L.
Blind Source Separation techniques, based both on Independent Component Analysis and on second order statistics, are presented and compared for extracting partially hidden texts and textures in document images. Barely perceivable features may occur, for instance, in ancient documents previously erased and then re-written (palimpsests), or for transparency or seeping of ink from the reverse side, or from watermarks in the paper. Detecting these features can be of great importance to scholars and historians. In our approach, the document is modeled as the superposition of a number of source patterns, and a simplified linear mixture model is introduced for describing the relationship between these sources and multispectral views of the document itself. The problem of detecting the patterns that are barely perceivable in the visible color image is thus formulated as the one of separating the various patterns in the mixtures. Some examples from an extensive experimentation with real ancient documents are shown and commented.Source: International Conference on Image Analysis and Recognition, pp. 241–248, Porto, Portugal, September
See at: CNR ExploRA
2004
Journal article
Unknown
CB-SPE tool: putting component-based performance engineering into practice
Bertolino A., Mirandola R.
A crucial issue in the design of Component-Based (CB) applications is the ability to early guarantee that the system under development will satisfy its Quality of Service requirements. In particular, we need rigorous and easy-to-use techniques for predicting and analyzing the performance of the assembly based on the properties of the constituent components. To this purpose, we propose the CB-SPE framework: a compositional methodology for CB Software Performance Engineering (SPE) and its supporting tool. CB-SPE is based on, and adapts to a CB paradigm, the concepts and steps of the well-known SPE technology, using for input modeling the standard RT-UML PA profile. The methodology is compositional: it is first applied by the component developer at the component layer, achieving a parametric performance evaluation of the components in isolation; then, at the application layer, the system assembler is provided with a step-wise procedure for predicting the performance of the as-sembled components on the actual platform. We have developed the CB-SPE tool reusing as much as possible existing free tools. In this paper we present the realized framework, together with a simple application example.Source: Lecture notes in computer science 3054 (2004): 233–248.
Bertolino A., Mirandola R.
A crucial issue in the design of Component-Based (CB) applications is the ability to early guarantee that the system under development will satisfy its Quality of Service requirements. In particular, we need rigorous and easy-to-use techniques for predicting and analyzing the performance of the assembly based on the properties of the constituent components. To this purpose, we propose the CB-SPE framework: a compositional methodology for CB Software Performance Engineering (SPE) and its supporting tool. CB-SPE is based on, and adapts to a CB paradigm, the concepts and steps of the well-known SPE technology, using for input modeling the standard RT-UML PA profile. The methodology is compositional: it is first applied by the component developer at the component layer, achieving a parametric performance evaluation of the components in isolation; then, at the application layer, the system assembler is provided with a step-wise procedure for predicting the performance of the as-sembled components on the actual platform. We have developed the CB-SPE tool reusing as much as possible existing free tools. In this paper we present the realized framework, together with a simple application example.Source: Lecture notes in computer science 3054 (2004): 233–248.
See at: CNR ExploRA
2004
Journal article
Open Access
Composing event constraints in state-based specification
Bolognesi T.
Event-based process algebraic specification languages support an elegant specification technique by which system behaviours are described as compositions of constraints on event occurrences and event parameters. This paper investigates the possibility to export this specification paradigm to a state-based formalism, and discusses some deriving advantages in terms of verification.Source: Lecture notes in computer science 3235 (2004): 13–32. doi:10.1007/978-3-540-30232-2_2
DOI: 10.1007/978-3-540-30232-2_2
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Bolognesi T.
Event-based process algebraic specification languages support an elegant specification technique by which system behaviours are described as compositions of constraints on event occurrences and event parameters. This paper investigates the possibility to export this specification paradigm to a state-based formalism, and discusses some deriving advantages in terms of verification.Source: Lecture notes in computer science 3235 (2004): 13–32. doi:10.1007/978-3-540-30232-2_2
DOI: 10.1007/978-3-540-30232-2_2
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link.springer.com | www.springerlink.com | doi.org | CNR ExploRA