687 research outputs found
Profiling distributed graph processing systems through visual analytics
No full textAnalyzing large-scale graphs provides valuable insights in different application scenarios, including social networking, crime detection, content ranking, and recommendations. While many graph processing systems working on top of distributed infrastructures have been proposed to deal with big graphs, the task of profiling their massive computations remains time consuming and error-prone. This paper presents GiViP, a visual profiler for distributed graph processing systems based on a Pregel-like computation model. GiViP captures the huge amount of messages exchanged throughout a computation and provides a powerful user interface for the visual analysis of the collected data. We discuss the effectiveness of our approach and show how to take advantage of GiViP to detect anomalies related to the computation and to the infrastructure, such as slow computing units, anomalous message patterns, unbalanced graph partitions, and links with high latency
A Million Edge Drawing for a Fistful of Dollars
No full textIn this paper we study the problem of designing a graph drawing algorithm for large graphs. The algorithm must be simple to implement and the computing infrastructure must not require major hardware or software investments. We report about the experimental analysis of a simple implementation of a spring embedder in Giraph, a vertex-centric open source framework for distributed computing. The algorithm is tested on real graphs of up to 1 million edges by using a cheap PaaS (Platform as a Service) infrastructure of Amazon. We can afford drawing graphs with about one million edges in about 8 min, by spending less than 1 USD per drawing for the cloud computing infrastructure
Large graph visualizations using a distributed computing platform
No full textBig Data analytics is recognized as one of the major issues in our current information society, and raises several challenges and opportunities in many fields, including economy and finance, e-commerce, public health and administration, national security, and scientific research. The use of visualization techniques to make sense of large volumes of information is an essential ingredient, especially for the analysis of complex interrelated data, which are represented as graphs. The growing availability of powerful and inexpensive cloud computing services naturally motivates the study of distributed graph visualization algorithms, able to scale to the size of large graphs. We study the problem of designing a distributed visualization algorithm that must be simple to implement and whose computing infrastructure does not require major hardware or software investments. We design, implement, and experiment a force-directed algorithm in Giraph, a popular open source framework for distributed computing, based on a vertex-centric design paradigm. The algorithm is tested both on real and artificial graphs with up to one million edges. The experiments show the scalability and effectiveness of our technique when compared to a centralized implementation of the same force-directed model. Graphs with about one million edges can be drawn in a few minutes, by spending about 1 USD per drawing with a cloud computing infrastructure of Amazon
A Distributed Multilevel Force-Directed Algorithm
No full textThe wide availability of powerful and inexpensive cloud computing services naturally motivates the study of distributed graph layout algorithms, able to scale to very large graphs. Nowadays, to process Big Data, companies are increasingly relying on PaaS infrastructures rather than buying and maintaining complex and expensive hardware. So far, only a few examples of basic force-directed algorithms that work in a distributed environment have been described. Instead, the design of a distributed multilevel force-directed algorithm is a much more challenging task, not yet addressed. We present the first multilevel force-directed algorithm based on a distributed vertex-centric paradigm, and its implementation on Giraph, a popular platform for distributed graph algorithms. Experiments show the effectiveness and the scalability of the approach. Using an inexpensive cloud computing service of Amazon, we draw graphs with ten million edges in about 60 min
The Pottesman Collection in the British Museum. Early Dynastic and Sargonic administrative texts. With an Appendix on a Palmyrene Inscription
No full textEdizione, trascrizione, traduzione e commento di un frammento di iscrizione palmirena inedita presente nella collezione Pottesman del British Museum (Appendice Agostini).The British Museum houses a small collection of six cuneiform tablets and a Palmyrene dedicatory inscription purchased in 1987 from the private collection of Solomon Pottesman. The aim of the present contribution is to provide a catalog of this lot and an edition of the so far unpublished cuneiform texts. In the appendix, Alessio Agostini added the edition of the Palmyrene inscription, which would have otherwise gone beyond the capabilities of the present author
Recensione di Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
No full textReview of Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
Author: Alessio MagogaRecensione di Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
Autor: Alessio Magog
Handheld-Impedance-Measurement System with seven-decade capability and potentiostatic function
Full text linkThis paper describes design and test of a new impedance-measurement system for nonlinear devices that exhibits a seven-decade range and works down to a frequency of 0.01 Hz. The system is specifically designed for electrochemical measurements, but the proposed architecture can be employed in many other fields where flexible signal generation and analysis are required. The system employs an unconventional signal generator based on two pulsewidth modulation (PWM) oscillators and an autocalibration system that allows uncertainties of less than 3% to be obtained over a range of 1 kΩ to 100 GΩ. A synchronous demodulation processing allows the noise superimposed to the low-amplitude input signals to be made negligibl
El Tlacuache Núm. 16 (2001). 16 Año 1 (2001) octubre. El Tlacuache
No full text- ¿Entre la Guerra Santa y la Cruzada? por Aníbal Quijano. - Nuestro patrimonio desconocido por Teresita Loera y Anaite Monterforte. - El Yahutli por Margarita Avilés y Macrina Fuentes. - Haciendas por Carlos Fernando Alessio Robles
El Tlacuache Núm. 19 (2001). 19 Año 1 (2001) noviembre. El Tlacuache
No full text- Patrimonio cultural y monumento histórico: Tlayacapan un monasterio Agustino por Carlos Alessio Robles. - Nuestro patrimonio desconocido por Teresita Loera y Anaite Monterforte. - El Yauhtli por Margarita Avilés y Macrina Fuentes. - ¿Entre la Guerra Santa y la Cruzada? por Aníbal Quijano
Il GEIE "italiano" tra impresa e società
Full text linkA quasi trent’anni dall’emanazione del Regolamento comunitario 2137/1985 che ne segna la data di nascita, e a venticinque dalla effettiva possibilità di costituzione, il gruppo europeo di interesse economico (GEIE) è ancora percepito, nella migliore delle ipotesi, come una specie di “oggetto misterioso” nel panorama giuridico italiano ed europeo. Lo scopo di questo studio, che ha beneficiato del sostegno economico della Commissione Europea e della Provincia autonoma di Trento nell’ambito del Settimo Programma Quadro, Azione Marie Curie COFUND, progetto “TRENTINO”, è di tentare una riconduzione ragionata del GEIE a categorie che siano di maggiore familiarità per il giurista italiano, indagandone le problematiche principali (su tutte l’assenza del beneficio della responsabilità limitata dei membri per le obbligazioni assunte dal gruppo) ed offrendo ipotesi di soluzione
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