http://hdl.handle.net/2117/223 Tue, 21 May 2013 04:29:43 GMT 2013-05-21T04:29:43Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19354 Title: FRA: A new fuzzy-based routing approach for optical transport networks Authors: Ahvar, E.; Marín Tordera, Eva; Yannuzzi, Marcelo; Masip Bruin, Xavier; Ahvar, S. Abstract: Providing networks with QoS guarantees is one of the key issues to support current and future expected clients' demands. In this scenario, QoS routing is definitely critical as being responsible for defining those optimal routes supporting traffic forwarding throughout the whole network. This paper proposes two new QoS-aware RWA algorithms dealing with the routing inaccuracy problem, aiming at reducing blocking probability while limiting signaling overhead and balancing network load. The proposed algorithms extend the work already published by the authors on prediction based routing by adding a novel fuzzy-based technique featuring a powerful tool for modeling uncertainty. The proposed algorithms are compared with a well-known RWA algorithm and results show the benefit of introducing the fuzzy techniques in the RWA selection. Mon, 20 May 2013 07:09:37 GMT http://hdl.handle.net/2117/19354 2013-05-20T07:09:37Z Ahvar, E.; Marín Tordera, Eva; Yannuzzi, Marcelo; Masip Bruin, Xavier; Ahvar, S. no prediction based routing, routing inaccuracy problem, RWA Providing networks with QoS guarantees is one of the key issues to support current and future expected clients' demands. In this scenario, QoS routing is definitely critical as being responsible for defining those optimal routes supporting traffic forwarding throughout the whole network. This paper proposes two new QoS-aware RWA algorithms dealing with the routing inaccuracy problem, aiming at reducing blocking probability while limiting signaling overhead and balancing network load. The proposed algorithms extend the work already published by the authors on prediction based routing by adding a novel fuzzy-based technique featuring a powerful tool for modeling uncertainty. The proposed algorithms are compared with a well-known RWA algorithm and results show the benefit of introducing the fuzzy techniques in the RWA selection. http://hdl.handle.net/2117/19349 Title: Segmentation robust to the vignette effect for machine vision systems Authors: Karatzas, D; Rusiñol, Marçal; Antens, Coen; Ferrer Sumsi, Miquel Abstract: The vignette effect (radial fall-off) is commonly encountered in images obtained through certain image acquisition setups and can seriously hinder automatic analysis processes. In this paper we present a fast and efficient method for dealing with vignetting in the context of object segmentation in an existing industrial inspection setup. The vignette effect is modelled here as a circular, non-linear gradient. The method estimates the gradient parameters and employs them to perform segmentation. Segmentation results on a variety of images indicate that the presented method is able to successfully tackle the vignette effect. Fri, 17 May 2013 14:48:37 GMT http://hdl.handle.net/2117/19349 2013-05-17T14:48:37Z Karatzas, D; Rusiñol, Marçal; Antens, Coen; Ferrer Sumsi, Miquel no The vignette effect (radial fall-off) is commonly encountered in images obtained through certain image acquisition setups and can seriously hinder automatic analysis processes. In this paper we present a fast and efficient method for dealing with vignetting in the context of object segmentation in an existing industrial inspection setup. The vignette effect is modelled here as a circular, non-linear gradient. The method estimates the gradient parameters and employs them to perform segmentation. Segmentation results on a variety of images indicate that the presented method is able to successfully tackle the vignette effect. http://hdl.handle.net/2117/19347 Title: Combination of OCR engines for page segmentation based on performance evaluation Authors: Ferrer Sumsi, Miquel; Valveny, Ernest Abstract: In this paper we present a method to improve the performance of individual page segmentation engines based on the combination of the output of several engines. The rules of combination are designed after analyzing the results of each individual method. This analysis is performed using a performance evaluation framework that aims at characterizing each method according to its strengths and weaknesses rather than computing a single performance measure telling which is the "best" segmentation method. Fri, 17 May 2013 14:31:18 GMT http://hdl.handle.net/2117/19347 2013-05-17T14:31:18Z Ferrer Sumsi, Miquel; Valveny, Ernest no In this paper we present a method to improve the performance of individual page segmentation engines based on the combination of the output of several engines. The rules of combination are designed after analyzing the results of each individual method. This analysis is performed using a performance evaluation framework that aims at characterizing each method according to its strengths and weaknesses rather than computing a single performance measure telling which is the "best" segmentation method. http://hdl.handle.net/2117/19344 Title: An iterative algorithm for approximate median graph computation Authors: Ferrer Sumsi, Miquel; Bunke, Horst Abstract: Recently, the median graph has been shown to be a good choice to obtain a representative of a given set of graphs. It has been successfully applied to graph-based classification and clustering. In this paper we exploit a theoretical property of the median, which has not yet been utilized in the past, to derive a new iterative algorithm for approximate median graph computation. Experiments done using five different graph databases show that the proposed approach yields, in four out of these five datasets, better medians than two of the previous existing methods. Fri, 17 May 2013 14:07:48 GMT http://hdl.handle.net/2117/19344 2013-05-17T14:07:48Z Ferrer Sumsi, Miquel; Bunke, Horst no Recently, the median graph has been shown to be a good choice to obtain a representative of a given set of graphs. It has been successfully applied to graph-based classification and clustering. In this paper we exploit a theoretical property of the median, which has not yet been utilized in the past, to derive a new iterative algorithm for approximate median graph computation. Experiments done using five different graph databases show that the proposed approach yields, in four out of these five datasets, better medians than two of the previous existing methods. http://hdl.handle.net/2117/19343 Title: On the design of a UAS flight plan monitoring and edition system Authors: Pastor Llorens, Enric; Santamaria Barnadas, Eduard; Royo Chic, Pablo; López Rubio, Juan; Barrado Muxí, Cristina Abstract: This paper addresses various aspects of the design and development of the pilot interface for the exploitation of highly advanced flight plan capabilities specifically designed for Unmanned Aerial Systems (UAS). This flight plan capabilities are built on top a flexible and reusable hardware/software architecture designed to facilitate the development of UAS-based applications. This flexibility is organized into an user-parameterizable UAS Service Abstraction Layer (USAL). The USAL defines a collection of standard services are their interrelations as a basic starting point for further development by UAS users. Previous research presented the advanced flying capabilities of a UAS as an extension of the Flight Control System (FCS) functionalities. Assuming a UAS with a FCS that ensures safe and stable maneuvers, we complement it with a highly capable flight plan management system. USAL flight plan is characterized by offering semantically much richer constructs than those present in most current UAS autopilots, which rely on simple lists of waypoints. This list of waypoints approach has several important limitations: it is difficult to specify complex trajectories and it does not support constructs such as conditional forks or iterations, small changes may imply having to deal with a considerable amount of waypoints and it provides no mechanism for adapting to mission time circumstances. To address these issues a new flight plan specification mechanism is proposed, that incorporates a leg concept extended to accommodate higher level constructs for specifying iterations and forks. Additional leg types, referred to as parametric leg, are also introduced. The trajectory defined by a parametric leg is automatically generated as a function of mission variables, enabling dynamic behavior and providing a very valuable means for adapting the flight to the mission evolution. Another level of adaption is provided by the conditions governing the decision-making in intersection le- - gs and the finalization of iterative legs. In this work we will focus on the development of the pilot interface for the exploitation of the introduced flight plan capabilities. The interface design requirements address an increase level of automated operation and support to react to unexpected requirements due to mission changes. Therefore, this interaction includes the available mechanisms to update the flight-plan according to UAS mission requirements, skip parts of it, react to operational contingencies, etc. Fri, 17 May 2013 14:02:55 GMT http://hdl.handle.net/2117/19343 2013-05-17T14:02:55Z Pastor Llorens, Enric; Santamaria Barnadas, Eduard; Royo Chic, Pablo; López Rubio, Juan; Barrado Muxí, Cristina no This paper addresses various aspects of the design and development of the pilot interface for the exploitation of highly advanced flight plan capabilities specifically designed for Unmanned Aerial Systems (UAS). This flight plan capabilities are built on top a flexible and reusable hardware/software architecture designed to facilitate the development of UAS-based applications. This flexibility is organized into an user-parameterizable UAS Service Abstraction Layer (USAL). The USAL defines a collection of standard services are their interrelations as a basic starting point for further development by UAS users. Previous research presented the advanced flying capabilities of a UAS as an extension of the Flight Control System (FCS) functionalities. Assuming a UAS with a FCS that ensures safe and stable maneuvers, we complement it with a highly capable flight plan management system. USAL flight plan is characterized by offering semantically much richer constructs than those present in most current UAS autopilots, which rely on simple lists of waypoints. This list of waypoints approach has several important limitations: it is difficult to specify complex trajectories and it does not support constructs such as conditional forks or iterations, small changes may imply having to deal with a considerable amount of waypoints and it provides no mechanism for adapting to mission time circumstances. To address these issues a new flight plan specification mechanism is proposed, that incorporates a leg concept extended to accommodate higher level constructs for specifying iterations and forks. Additional leg types, referred to as parametric leg, are also introduced. The trajectory defined by a parametric leg is automatically generated as a function of mission variables, enabling dynamic behavior and providing a very valuable means for adapting the flight to the mission evolution. Another level of adaption is provided by the conditions governing the decision-making in intersection le- - gs and the finalization of iterative legs. In this work we will focus on the development of the pilot interface for the exploitation of the introduced flight plan capabilities. The interface design requirements address an increase level of automated operation and support to react to unexpected requirements due to mission changes. Therefore, this interaction includes the available mechanisms to update the flight-plan according to UAS mission requirements, skip parts of it, react to operational contingencies, etc. http://hdl.handle.net/2117/19342 Title: An approximate algorithm for median graph computation using graph embedding Authors: Ferrer Sumsi, Miquel; Valveny, Ernest; Serratosa Casanelles, Francesc; Riesen, Kaspar; Bunke, Horst Abstract: Graphs are powerful data structures that have many attractive properties for object representation. However, some basic operations are difficult to define and implement, for instance, how to obtain a representative of a set of graphs. The median graph has been defined for that purpose, but existing algorithms are computationally complex and have a very limited applicability. In this paper we propose a new approach for the computation of the median graph based on graph embedding in vector spaces. Experiments on a real database containing large graphs show that we succeed to compute good approximations of the median graph. We have also applied the median graph to perform some basic classification tasks achieving reasonable good results. Fri, 17 May 2013 13:58:08 GMT http://hdl.handle.net/2117/19342 2013-05-17T13:58:08Z Ferrer Sumsi, Miquel; Valveny, Ernest; Serratosa Casanelles, Francesc; Riesen, Kaspar; Bunke, Horst no Graphs are powerful data structures that have many attractive properties for object representation. However, some basic operations are difficult to define and implement, for instance, how to obtain a representative of a set of graphs. The median graph has been defined for that purpose, but existing algorithms are computationally complex and have a very limited applicability. In this paper we propose a new approach for the computation of the median graph based on graph embedding in vector spaces. Experiments on a real database containing large graphs show that we succeed to compute good approximations of the median graph. We have also applied the median graph to perform some basic classification tasks achieving reasonable good results. http://hdl.handle.net/2117/19325 Title: Sinopsis y notas de trabajo sobre autocad: inventario y propuestas Authors: Nogués Mañé, Carlos Abstract: En los últimos años de docencia he venido redactando cortas monografías para poner en orden mis propias ideas y fijar conclusiones sobre el funcionamiento de AutoCAD en sus distintas versiones, porque los manuales suelen pasar de puntillas sobre las cuestiones espinosas. También los recorridos transversales, sobre los diferentes temas que afectan a una cuestión o su evolución a lo largo de sucesivas versiones, son recomendables para contrarrestar la excesiva parcelación de las exposiciones sistemáticas. De todo este material, sólo una parte ha sido incluida en los apuntes de clase porque el resto es más bien letra pequeña sólo apta para especialistas, si bien podría ser útil su difusión aunque sólo fuera para evitar a sus potenciales lectores quemar muchas horas frente al ordenador: dado el mutismo o poca claridad de los manuales, la vía empírica es el único medio para alcanzar certezas. Como supongo que numerosos profesionales y docentes, con AutoCAD como herramienta habitual u objeto de estudio, deben compartir tales inquietudes y hábitos, presento un inventario de las 30 fichas realizadas hasta ahora, a disposición de cuantos acepten la filosofía del "quid pro quo". Incluyo la invitación a colaborar, por puro placer, en el diseño de un simulador de reactivo posicional de cursor. ABSTRACT During the past few years, in view of the tendency of manuals to pass quickly over difficult issues, I have written several short articles on the different versions of AutoCAD. Also, the excessive divisions used in most systematic presentations mean that a lateral overview, looking at the different themes that affect an issue or its evolution through successive versions, is advisab le and a welcome contrast. From all this material, only a small amount has been included in the class notes since the rest is really the small print which is only of interest to the expert. However, it could well be useful to publish it, if only to ensure that potential readers do not waste many hours glued to their compared screens: in view of the lack of clarity in the manuals, experience is the only way to arrive at certain results. As I suppose that many professionals and educators (who use AutoCAD as an everyday tool, or who study it) must share my concerns and methods, I am providing a list of the 30 files I have written so far. They are available to all those who accept the philosophy of "quid pro quo". I would also like to invite anyone who is interested in collaborating, for the pure pleasure of it, in the design of a cursor position reactor simulator. Fri, 17 May 2013 08:32:55 GMT http://hdl.handle.net/2117/19325 2013-05-17T08:32:55Z Nogués Mañé, Carlos no En los últimos años de docencia he venido redactando cortas monografías para poner en orden mis propias ideas y fijar conclusiones sobre el funcionamiento de AutoCAD en sus distintas versiones, porque los manuales suelen pasar de puntillas sobre las cuestiones espinosas. También los recorridos transversales, sobre los diferentes temas que afectan a una cuestión o su evolución a lo largo de sucesivas versiones, son recomendables para contrarrestar la excesiva parcelación de las exposiciones sistemáticas. De todo este material, sólo una parte ha sido incluida en los apuntes de clase porque el resto es más bien letra pequeña sólo apta para especialistas, si bien podría ser útil su difusión aunque sólo fuera para evitar a sus potenciales lectores quemar muchas horas frente al ordenador: dado el mutismo o poca claridad de los manuales, la vía empírica es el único medio para alcanzar certezas. Como supongo que numerosos profesionales y docentes, con AutoCAD como herramienta habitual u objeto de estudio, deben compartir tales inquietudes y hábitos, presento un inventario de las 30 fichas realizadas hasta ahora, a disposición de cuantos acepten la filosofía del "quid pro quo". Incluyo la invitación a colaborar, por puro placer, en el diseño de un simulador de reactivo posicional de cursor. ABSTRACT During the past few years, in view of the tendency of manuals to pass quickly over difficult issues, I have written several short articles on the different versions of AutoCAD. Also, the excessive divisions used in most systematic presentations mean that a lateral overview, looking at the different themes that affect an issue or its evolution through successive versions, is advisab le and a welcome contrast. From all this material, only a small amount has been included in the class notes since the rest is really the small print which is only of interest to the expert. However, it could well be useful to publish it, if only to ensure that potential readers do not waste many hours glued to their compared screens: in view of the lack of clarity in the manuals, experience is the only way to arrive at certain results. As I suppose that many professionals and educators (who use AutoCAD as an everyday tool, or who study it) must share my concerns and methods, I am providing a list of the 30 files I have written so far. They are available to all those who accept the philosophy of "quid pro quo". I would also like to invite anyone who is interested in collaborating, for the pure pleasure of it, in the design of a cursor position reactor simulator. http://hdl.handle.net/2117/19324 Title: AutoCAD: adaptación de un bloque ortonormal 2d(3d) a un paralelogramo (paralelepípedo) dado Authors: Nogués Mañé, Carlos Abstract: Si se ha tenido la precaución de referir a un bloque 2D un cuadrado unitario ortogonal, será inmediato insertarlo de manera que éste se adapte a cualquier marco rectangular establecido en el dibujo. Sin embargo, la inmediatez desaparece si pretendemos encadenar inserciones de manera que, además de una combinación simple de escalado, giro y traslación, se halle implícita una transformación de cortadura: cuando el marco receptor sea un paralelógramo oblicuo. Porque está claro que si insertamos el bloque girado, convertimos la inserción en bloque y volvemos a insertar, esta vez con escalado no uniforme, la figura transformada del primitivo cuadrado de referencia será un paralelógramo, pero el problema es: dado un marco romboidal concreto, ¿con qué giro hay que realizar la primera inserción, y qué giro y factores de escala debemos aplicar a la segunda para que el cuadrado de referencia se ciña al marco? El problema se complica si queremos aprovechar el resultado de la primera inserción para adaptaciones a otros paralelógramos, creando un si stema no redundante de inserciones intermedias, pero se ha diseñado un programa AutoLISP que resu elve estas cuestiones en 2D, en 3D y puede operar con bloques con atributos, no sólo situados en el plano base sino ubicados y orientados libremente. ABSTRACT If we reference an orthogonal unit square to a 2D-block, the block can immediately be inserted in such a way that the orthogonal unit square adapts to any existing rectangular frame in the drawing. However, this immediacy is lost if we wish to perform a series of insertions in such a way that, in addition to a simple combination of scaling, rotating and translating, they implicitly include a shearing transformation when the receiving frame is an oblique parallelogram. This is because if we rotate the block and then insert it, convert the insertion into a block and reinsert (this time using a non-uniform scale factor), the figure resulting from this transformation of the original reference square will be a parallelogram. However, the question we wish to tackle is the following. Given a specific rhomboid frame, exactly what rotation do we need when making the first insertion, and what rotation and scale factors must we apply when inserting for the second time, in order to ensure that the reference square fits the frame exactly? The problem becomes more complicated if we wish to use the result of the first insertion and adapt it for other parallelograms, creating a non-redundant system of intermediate insertions. An AutoLISP program has been designe d which solves these problems in 2D and in 3D. Furthermore, it can cope with blocks that do not sit squarely on the flat base, but which are arbitrarily located and orientated. Fri, 17 May 2013 08:08:59 GMT http://hdl.handle.net/2117/19324 2013-05-17T08:08:59Z Nogués Mañé, Carlos no Si se ha tenido la precaución de referir a un bloque 2D un cuadrado unitario ortogonal, será inmediato insertarlo de manera que éste se adapte a cualquier marco rectangular establecido en el dibujo. Sin embargo, la inmediatez desaparece si pretendemos encadenar inserciones de manera que, además de una combinación simple de escalado, giro y traslación, se halle implícita una transformación de cortadura: cuando el marco receptor sea un paralelógramo oblicuo. Porque está claro que si insertamos el bloque girado, convertimos la inserción en bloque y volvemos a insertar, esta vez con escalado no uniforme, la figura transformada del primitivo cuadrado de referencia será un paralelógramo, pero el problema es: dado un marco romboidal concreto, ¿con qué giro hay que realizar la primera inserción, y qué giro y factores de escala debemos aplicar a la segunda para que el cuadrado de referencia se ciña al marco? El problema se complica si queremos aprovechar el resultado de la primera inserción para adaptaciones a otros paralelógramos, creando un si stema no redundante de inserciones intermedias, pero se ha diseñado un programa AutoLISP que resu elve estas cuestiones en 2D, en 3D y puede operar con bloques con atributos, no sólo situados en el plano base sino ubicados y orientados libremente. ABSTRACT If we reference an orthogonal unit square to a 2D-block, the block can immediately be inserted in such a way that the orthogonal unit square adapts to any existing rectangular frame in the drawing. However, this immediacy is lost if we wish to perform a series of insertions in such a way that, in addition to a simple combination of scaling, rotating and translating, they implicitly include a shearing transformation when the receiving frame is an oblique parallelogram. This is because if we rotate the block and then insert it, convert the insertion into a block and reinsert (this time using a non-uniform scale factor), the figure resulting from this transformation of the original reference square will be a parallelogram. However, the question we wish to tackle is the following. Given a specific rhomboid frame, exactly what rotation do we need when making the first insertion, and what rotation and scale factors must we apply when inserting for the second time, in order to ensure that the reference square fits the frame exactly? The problem becomes more complicated if we wish to use the result of the first insertion and adapt it for other parallelograms, creating a non-redundant system of intermediate insertions. An AutoLISP program has been designe d which solves these problems in 2D and in 3D. Furthermore, it can cope with blocks that do not sit squarely on the flat base, but which are arbitrarily located and orientated. http://hdl.handle.net/2117/19315 Title: Editorial for the special issue on graph-based representations in pattern recognition Authors: Torsello, Andrea; Jiang, Xiaoyi; Ferrer Sumsi, Miquel Thu, 16 May 2013 14:31:19 GMT http://hdl.handle.net/2117/19315 2013-05-16T14:31:19Z Torsello, Andrea; Jiang, Xiaoyi; Ferrer Sumsi, Miquel no http://hdl.handle.net/2117/19311 Title: Energy-efficiency and security issues in the Cisco Nexus virtual distributed switching Authors: Peterson, Benjamin; Ricciardi, Sergio; Nin Guerrero, Jordi Abstract: Virtualization technologies have brought with them the promise of increased security and energy saving. Such was the case with the Cisco Nexus virtual switching environment. However, possible security issues of this environment have not been evaluated and the achievable energy savings have not been quantified yet. In particular, it was necessary to investigate whether the security vulnerabilities existing in physical switches had persisted into the virtual environment. This paper provides an evaluation of the energy saving and an analysis of the security implications of the Cisco Nexus virtual distributed switching environment. Thu, 16 May 2013 14:10:16 GMT http://hdl.handle.net/2117/19311 2013-05-16T14:10:16Z Peterson, Benjamin; Ricciardi, Sergio; Nin Guerrero, Jordi no Nexus 1000V, energy consumption, security in switching virtualization, virtual architectures Virtualization technologies have brought with them the promise of increased security and energy saving. Such was the case with the Cisco Nexus virtual switching environment. However, possible security issues of this environment have not been evaluated and the achievable energy savings have not been quantified yet. In particular, it was necessary to investigate whether the security vulnerabilities existing in physical switches had persisted into the virtual environment. This paper provides an evaluation of the energy saving and an analysis of the security implications of the Cisco Nexus virtual distributed switching environment. http://hdl.handle.net/2117/19310 Title: Cloud virtual machine scheduling: modelling the cloud virtual machine instantiation Authors: Sotiriadis, S.; Bessis, N.; Xhafa Xhafa, Fatos; Antonopoulos, Nicos Thu, 16 May 2013 13:55:24 GMT http://hdl.handle.net/2117/19310 2013-05-16T13:55:24Z Sotiriadis, S.; Bessis, N.; Xhafa Xhafa, Fatos; Antonopoulos, Nicos no Cloud, Static and dynamic virtual machine scheduling, Virtual machine instantiation, Virtualization http://hdl.handle.net/2117/19309 Title: Efficient graph management based on bitmap indices Authors: Martínez Bazán, Norbert; Muntés Mulero, Víctor; Gómez Villamor, S.; Dominguez Sal, D.; Águila Lorente, Miguel Ángel; Larriba Pey, Josep Abstract: The increasing amount of graph like data from social networks, science and the web has grown an interest in analyzing the relationships between different entities. New specialized solutions in the form of graph databases, which are generic and able to adapt to any schema as an alternative to RDBMS, have appeared to manage attributed multigraphs efficiently. In this paper, we describe the internals of DEX graph database, which is based on a representation of the graph and its attributes as maps and bitmap structures that can be loaded and unloaded efficiently from memory. We also present the internal operations used in DEX to manipulate these structures. We show that by using these structures, DEX scales to graphs with billions of vertices and edges with very limited memory requirements. Finally, we compare our graph-oriented approach to other approaches showing that our system is better suited for out-of-core typical graph-like operations. Thu, 16 May 2013 13:52:00 GMT http://hdl.handle.net/2117/19309 2013-05-16T13:52:00Z Martínez Bazán, Norbert; Muntés Mulero, Víctor; Gómez Villamor, S.; Dominguez Sal, D.; Águila Lorente, Miguel Ángel; Larriba Pey, Josep no Data representation, Graph databases, Query performance The increasing amount of graph like data from social networks, science and the web has grown an interest in analyzing the relationships between different entities. New specialized solutions in the form of graph databases, which are generic and able to adapt to any schema as an alternative to RDBMS, have appeared to manage attributed multigraphs efficiently. In this paper, we describe the internals of DEX graph database, which is based on a representation of the graph and its attributes as maps and bitmap structures that can be loaded and unloaded efficiently from memory. We also present the internal operations used in DEX to manipulate these structures. We show that by using these structures, DEX scales to graphs with billions of vertices and edges with very limited memory requirements. Finally, we compare our graph-oriented approach to other approaches showing that our system is better suited for out-of-core typical graph-like operations. http://hdl.handle.net/2117/19307 Title: Cuckoo sampling: robust collection of flow aggregates under a fixed memory budget Authors: Sanjuàs Cuxart, Josep; Barlet Ros, Pere; Duffield, Nick; Kompella, Ramana Abstract: Collecting per-flow aggregates in high-speed links is challenging and usually requires traffic sampling to hand le peak rates and extreme traffic mixes. Static selection of sam pling rates is problematic, since worst-case resource usage is or ders of magnitude higher than the average. To address this issue, adaptive schemes have been proposed in the last few years tha t periodically adjust packet sampling rates to network condi tions. However, such proposals rely on complex algorithms and data structures of costly maintenance. As a consequence, adapti ve sampling is still not widely implemented in routers. We present a novel flow sampling based measurement scheme called Cuckoo Sampling that efficiently collects per-flow ag gre- gates, while smoothly discarding information as it exceeds the available memory. After a measurement epoch, it provides a random sample of the input flows, at a close-to-maximum rate as allowed by the available memory budget. Our proposal relies on a very simple data structure, require s few per-packet operations, has a CPU cost that is independen t of the memory budget and traffic profile, and is suitable for hardware implementation. We back the theoretical analysis of the algorithm with experiments with both synthetic and real net work traffic, and show that our algorithm requires significantly l ess resources than existing adaptive sampling schemes Thu, 16 May 2013 13:38:48 GMT http://hdl.handle.net/2117/19307 2013-05-16T13:38:48Z Sanjuàs Cuxart, Josep; Barlet Ros, Pere; Duffield, Nick; Kompella, Ramana no Adaptive sampling, Adaptive scheme, Complex algorithms, Fixed memory budget, High-speed links, Network condition, Orders of magnitude, Packet sampling, Resource usage, Sampling rates, Traffic mix, Traffic sampling Collecting per-flow aggregates in high-speed links is challenging and usually requires traffic sampling to hand le peak rates and extreme traffic mixes. Static selection of sam pling rates is problematic, since worst-case resource usage is or ders of magnitude higher than the average. To address this issue, adaptive schemes have been proposed in the last few years tha t periodically adjust packet sampling rates to network condi tions. However, such proposals rely on complex algorithms and data structures of costly maintenance. As a consequence, adapti ve sampling is still not widely implemented in routers. We present a novel flow sampling based measurement scheme called Cuckoo Sampling that efficiently collects per-flow ag gre- gates, while smoothly discarding information as it exceeds the available memory. After a measurement epoch, it provides a random sample of the input flows, at a close-to-maximum rate as allowed by the available memory budget. Our proposal relies on a very simple data structure, require s few per-packet operations, has a CPU cost that is independen t of the memory budget and traffic profile, and is suitable for hardware implementation. We back the theoretical analysis of the algorithm with experiments with both synthetic and real net work traffic, and show that our algorithm requires significantly l ess resources than existing adaptive sampling schemes http://hdl.handle.net/2117/19306 Title: Performance analysis of DSR and DYMO routing protocols for VANETs Authors: Spaho, Evjola; Ikeda, Makoto; Barolli, Leonard; Xhafa Xhafa, Fatos; Kolici, Vladi; Takizawa, Makoto Thu, 16 May 2013 13:36:45 GMT http://hdl.handle.net/2117/19306 2013-05-16T13:36:45Z Spaho, Evjola; Ikeda, Makoto; Barolli, Leonard; Xhafa Xhafa, Fatos; Kolici, Vladi; Takizawa, Makoto no DSR, DYMO, Routing protocols, VANETs http://hdl.handle.net/2117/19304 Title: Performance evaluation of WMN-GA system for low densities of clients and different settings of population size Authors: Oda, Tetsuya; Barolli, Admir; Spaho, Evjola; Barolli, Leonard; Xhafa Xhafa, Fatos; Takizawa, Makoto Thu, 16 May 2013 13:22:36 GMT http://hdl.handle.net/2117/19304 2013-05-16T13:22:36Z Oda, Tetsuya; Barolli, Admir; Spaho, Evjola; Barolli, Leonard; Xhafa Xhafa, Fatos; Takizawa, Makoto no Genetic algorithms, Number of covered users, Population size, Size of giant component, Wireless Mesh Networks