Multi-word Relevant Expressions (REs) can be defined as sequences of words (n-grams) with strong semantic meaning, such as "ice melting" and "Ministere des Affaires Etrangeres", useful in Informati...
详细信息
ISBN:
(纸本)9781479989379
Multi-word Relevant Expressions (REs) can be defined as sequences of words (n-grams) with strong semantic meaning, such as "ice melting" and "Ministere des Affaires Etrangeres", useful in Information Retrieval, Document Clustering or Classification and Indexing of Documents. the need of extracting REs in several languages led research on statistical approaches rather than symbolic methods, since the former allow language-independence. Based on the assumption that REs have strong cohesion between their consecutive n-grams, the LocalMaxs algorithm is a language independent approach that extracts REs. Apart from its good precision, this extractor is time-consuming, being inoperable for Big Data if implemented in a sequential manner. this paper presents the first parallel and distributed version of this algorithm, achieving almost linear speedup and sizeup when processing corpora up to 1 billion words, using up to 54 virtual machines in a public cloud. this parallel version of the algorithm explores the statistical knowledge of the n-grams in the corpus, to promote the locality of the references.
Group membership protocols in distributed systems enable entities in a group to be aware of all other entities in the group. this information is essential for the system to perform as a cohesive unit collaborating to ...
详细信息
this work presents a high-order finite element solver developed in the MatLab environment with procedures for high performance computing based on a very simple domain decomposition technique. the code has been develop...
详细信息
ISBN:
(纸本)9781905088416
this work presents a high-order finite element solver developed in the MatLab environment with procedures for high performance computing based on a very simple domain decomposition technique. the code has been developed withthe goal of testing news procedures for the solution of finite elements problems using distributedcomputing. the code has been tested in many different problems including Poisson operator, Plane Stress, Plane Strain, Linear and Nonlinear Elasticity, Optimization, Contact and Reynolds Equation. this paper aims to present features of the developed software, mainly the aspects of domain decomposition and distributedcomputing.
In the context of renewable energy sources integration, the use of microgrids (MGs) with multiple distributed generation (DG) based on voltage source inverters is the solution to significantly reduce the influence of ...
详细信息
ISBN:
(纸本)9781467386173
In the context of renewable energy sources integration, the use of microgrids (MGs) with multiple distributed generation (DG) based on voltage source inverters is the solution to significantly reduce the influence of the unpredictable nature of the renewable energy sources on the grid. this paper focuses on the problem of uncertainties and disturbances found in such applications with various LCL filter parameters, load conditions and network conditions, and the problem of voltage control of inverter-interfaced microgrids with radial structure. the main objectives of this paper are to (i) design a robust low-order voltage controller which ensures robustness as well as desired performance of the microgrid system in spite of uncertain parameters;(ii) validate the complete model of MG under different operating conditions using a digital real-time simulator. this simulator is a beneficial tool that allows the verification of several scenarios with different operating conditions. It accelerates the testing process as compared to offline simulations, where computation time is much larger.
this paper describes how we solved 12 previously unsolved mixed-integer programming (MIP) instances from the MIPLIB benchmark sets. To achieve these results we used an enhanced version of ParaSCIP, setting a new recor...
详细信息
ISBN:
(纸本)9781509021406
this paper describes how we solved 12 previously unsolved mixed-integer programming (MIP) instances from the MIPLIB benchmark sets. To achieve these results we used an enhanced version of ParaSCIP, setting a new record for the largest scale MIP computation: up to 80,000 cores in parallel on the Titan supercomputer. In this paper we describe the basic parallelization mechanism of ParaSCIP, improvements of the dynamic load balancing and novel techniques to exploit the power of parallelization for MIP solving. We give a detailed overview of computing times and statistics for solving open MIPLIB instances.
Clusters of GPUs are emerging as a new computational scenario. Programming them requires the use of hybrid models that increase the complexity of the applications, reducing the productivity of programmers. We present ...
详细信息
ISBN:
(纸本)9780769546759
Clusters of GPUs are emerging as a new computational scenario. Programming them requires the use of hybrid models that increase the complexity of the applications, reducing the productivity of programmers. We present the implementation of OmpSs for clusters of GPUs, which supports asynchrony and heterogeneity for task parallelism. It is based on annotating a serial application with directives that are translated by the compiler. With it, the same program that runs sequentially in a node with a single GPU can run in parallel in multiple GPUs either local (single node) or remote (cluster of GPUs). Besides performing a task-based parallelization, the runtime system moves the data as needed between the different nodes and GPUs minimizing the impact of communication by using affinity scheduling, caching, and by overlapping communication withthe computational task. We show several applicactions programmed with OmpSs and their performance with multiple GPUs in a local node and in remote nodes. the results show good tradeoff between performance and effort from the programmer.
the parallel implementation of the revised simplex algorithm (RSA) using eta-factorization holds the promise of significant improvement in the execution time by virtue of the existence of a high degree of parallelism ...
详细信息
Recent trends towards real-time visualization of large, 3-D datasets have created extraordinary demands on CPU, memory, and I/O resources. In this paper we describe how a metacomputing environment was used to perform ...
详细信息
the enumeration of all maximal cliques in an undirected graph is a fundamental problem arising in several research areas. We consider maximal clique enumeration on shared-memory, multi-core architectures and introduce...
详细信息
ISBN:
(纸本)9781538606179
the enumeration of all maximal cliques in an undirected graph is a fundamental problem arising in several research areas. We consider maximal clique enumeration on shared-memory, multi-core architectures and introduce an approach consisting entirely of data-parallel operations, in an effort to achieve efficient and portable performance across different architectures. We study the performance of the algorithm via experiments varying over benchmark graphs and architectures. Overall, we observe that our algorithm achieves up to a 33-time speedup and 9-time speedup over state-of-the-art distributed and serial algorithms, respectively, for graphs with higher ratios of maximal cliques to total cliques. Further, we attain additional speedups on a GPU architecture, demonstrating the portable performance of our data-parallel design.
Server replication is an approach often used to improve service access efficiency and availability for a large number of clients. this paper adopts a simple service model and investigates a set of efficient algorithms...
详细信息
ISBN:
(纸本)0769521355
Server replication is an approach often used to improve service access efficiency and availability for a large number of clients. this paper adopts a simple service model and investigates a set of efficient algorithms for server selection in an anycast group under the condition of imprecise network delay. the algorithms use ticket-based probing approach to search the path with short delay and probe the server load at the same time and try to optimize the server and path delay at the same time. the simulation results demonstrate that our algorithms are efficient in terms of server response time for sever selection compared with several other server selection algorithms.
暂无评论