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Energy storage systems (ESSs) are a critical component of the electric grid, dispatching (charging and discharging) to performing grid applications such as frequency regulation, energy arbitrage, and peak shaving. Today, lithium-ion batteries are considered the best electrochemical ESSs in grid applications, and various cathode chemistries have been developed. On the electric grid, batteries can provide up to 13 ESS services, and different combinations of grid services and chemistries produce different battery aging and life performance under the given dispatch. Therefore, the characterization of each grid application dispatch can give an insight into optimal participation strategies for lithium-ion chemistries for each grid service. In this paper, an efficient algorithm is presented which uses a dispatch interval matrix to capture metrics in the ESS dispatch relevant to lithium-ion battery aging and performance, and implements unsupervised learning and dimensionality reduction on this matrix to produce characteristic duty cycles of the dispatch, from which synthetic duty cycles are produced that are suitable for laboratory testing and fast simulation. The algorithm is demonstrated for the dispatch under the grid application of peak shaving. Finally, an electrochemical-aging model is used to simulate a lithium-ion battery under both the original power dispatch and the synthetic duty cycle to validate the effectiveness of the method proposed in this paper to retain the operating stress factors.

Accurate measurement of polyp size during colonoscopy is crucial. The usefulness of cap-assisted colonoscopy and external grid application on monitor (gCAP) was evaluated for polyp size measurement in this 3-year, single-center, single-blind, randomized trial. Using the endoscopic forceps width as reference, the discrepancy percent (DP), error rate (ER), and measurement time were compared between gCAP and visual estimation (VE) after randomization. ER was calculated within a 20% and 33% limit. From the 111 patients, 280 polyps were measured. The mean polyp sizes were 4.0 ± 1.7 mm and 4.2 ± 1.8 mm with gCAP and VE, respectively (p = 0.368). Compared with that by the forceps method, DP was significantly lower in the gCAP group than in the VE group. Moreover, ER was significantly lower in the gCAP group within its preset limit. The measurement time was 4 s longer in the gCAP group than in the VE group (8.2 ± 4.8 s vs. 4.2 ± 1.5 s, p &lt, 0.001). However, the forceps method lasted 28 s longer than the others. On subgroup analysis by size, gCAP was more accurate for polyp size ≥5 mm. The gCAP method was more accurate for polyp size measurement than VE, especially for polyps ≥5 mm, and was more convenient than the forceps method.

By using bidirectional AC-DC power converters to interface the grid with the plug-in electric vehicles (PEV) batteries, the vehicle-to-grid (V2G) approach is enabled. By this approach, the PEVbatteries can work as distributed storage systems that deliver electric energy to the grid under peak power requests. In addition, the battery-converter set can be exploited to execute ancillary functionalities such as to stabilize the grid voltage by injecting reactive power and to improve the power grid quality by filtering current harmonics and by balancing the line currents. This paper presents at first some possible scenarios for the application of the V2G approach. Then the functionalities offered by the V2G approach are addressed. An improved controller is applied in order to achieve low input current harmonics. The Proportional resonant controller is utilized for the V2G mode. Compared with conventional PI controllers, the proposed controllers greatly enhance the grid connected converter's performance in the aspects of low harmonics output.

The recent years saw an evolution of Grid technologies from early ideas to production deployments. At the same time, the expectations for Grids shifted from idealistic hopes — buoyed by the successes of the initial testbeds — to disillusionment with available implementations when applied to large-scale general purpose computing. In this paper, we argue that a mature e-Infrastructure aiming to bridge the gaps between visions and realities cannot be delivered without introducing Service Level Management (SLM). To support this thesis, we present an analysis of the Grid foundations and definitions that shows that SLM-related ideas were incorporated in them from the beginning. Next, we describe how implementing SLM in Grids could improve the usability and user-experience of the infrastructure - both for its customers and service providers. We also present a selection of real-life Grid application scenarios that are important for the research communities supported by the Grid, but cannot be efficiently supported without the SLM process in place. In addition, the paper contains introduction to SLM, a discussion on what introducing SLM to Grids might mean in practice, and what were the current efforts already applied in this field.

We use Colored Petri Nets (CPNs) for the modeling and performance analysis of grid architectures. We define a strategy for the optimization of grid storage usage, based on the addition of data removal tasks to grid workflows. We evaluate the strategy by simulating our CPN model of the grid. Experiments show that the strategy significantly reduces the amount of storage space needed to execute a grid application.

Core Grid technologies are rapidly maturing, but there remains a shortage of real Grid applications. One important reason is the lack of a simple and high-level application programming toolkit, bridging the gap between existing Grid middleware and application-level needs. The Grid Application Toolkit (GAT), as currently developed by the EC-funded project GridLab [1], provides this missing functionality. As seen from the application, the GAT provides a unified simple programming interface to the Grid infrastructure, tailored to the needs of Grid application programmers and users. A uniform programming interface will be needed for application developers to create a new generation of "Grid-aware" applications. The GAT implementation handles both the complexity and the variety of existing Grid middleware services via so-called adaptors. Complementing existing Grid middleware, GridLab also provides high-level services to implement the GAT functionality. We present the GridLab software architecture, consisting of the GAT, environment-specific adaptors, and GridLab services. We elaborate the concepts underlying the GAT and outline the corresponding application programming interface. We present the functionality of GridLab's high-level services and demonstrate how a dynamic Grid application can easily benefit from the GAT. All GridLab software is open source and can be downloaded from the project Web site. © 2005 IEEE.

Battery Energy Storage Systems (BESSs) could contribute to the generation/consumption balance of the grid and could provide advanced functionalities at different grid levels (generation, T&D, end-user and RES integration). In this paper an analysis and comparison of Battery Energy Storage (BES) technologies for grid applications is carried out. The comparison is focused on the most installed technologies in the recent experimental BESS installations. Furthermore, the paper presents a new methodology aimed at selecting the most suitable BES technology for a specific grid application. This methodology defines a priority level for each technical and economical characteristic of the BES technologies. Finally, the proposed methodology is applied for a specific grid application confirming its contribution in the selection of the best-suited technology.

A detailed description of a new hybrid computational machinery devoted to the semiclassical direct calculation of atom–diatom reaction rate coefficients implemented on the production computing Grid of European Grid Infrastructures is given. Related validation and performance tests are reported and discussed. State to state reactive scattering computational results obtained for the N + N2 atom–diatom system are compared with those obtained using a HPC cluster.

A confluence of industry, social, environmental and economical drivers is creating new interest in electric energy storage systems. The limitation in the energy resources availability, the continuing increasing of the fossil fuels cost and the more attention to the earth ecosystem, is making storage systems a suitable solution in many applications ranging from grid application toward the industrial and transportation ones. In this paper a review of actual electrical storage technologies suitable for transportation and naval applications is provided with particular attention to the functionalities that is possible to introduce according to the selected technology. Moreover, the applications of storage systems in land and naval handling will be analyzed in details underlining the advantages deriving by the introduction of opportunely chosen storage units.

International audience; Grids reliability remains an order of magnitude below clusters on production infrastructures. This work is aims at improving grid application performances by improving the job submission system. A stochastic model, capturing the behavior of a complex grid workload management system is proposed. To instantiate the model, detailed statistics are extracted from dense grid activity traces. The model is exploited in a simple job resubmission strategy. It provides quantitative inputs to improve job submission performance and it enables quantifying the impact of faults and outliers on grid operations.

International audience; Grids have been developed to provide uniform access to computing and storage resources, but since existing grid infrastructures have been deployed within the context of distinct projects, technological choices have often differed. Many users need to use several grid infrastructures, and they are facing complexity because of these differences. Several existing tools hide the middleware heterogeneity for this very purpose. However, the existing infrastructures do not differ only by their middleware; they also differ by their policies (e.g. network filtering rules), the supported security contexts (e.g. known certificate authorities) and the worker nodes configuration (e.g. available commands and services, environment variables). This paper explains how JSAGA, an implementation of the OGF SAGA (Simple API for Grid Application) specification[8], addresses these issues to enable efficient and uniform usage of existing grid infrastructures, such as EGEE[12], OSG[13], DEISA[14], NAREGI[15]...

The work presented in this paper has been motivated by scientific necessity (primarily of the local scientific community) of running various (stochastic) simulations (in cluster/Grid environments), whose results often depend on the quality (distribution, nondeterminism, entropy, etc.) of used random numbers. Since true random numbersare impossible to generate with a finite state machine (such as today's computers), scientists are forced either to use specialized expensive hardware number generators, or, more frequently, to content themselves with suboptimal solutions (like pseudorandom numbers generators). Quantum Random Bit Generator Servicehas begun as a result of an attempt to fulfill the scientists' needs for quality random numbers, but has now grown to a global (public) high-quality true random numbers service.

Application deployment is becoming an increasingly hard task, as complex, component-based Grid applications have to be deployed on heterogeneous and dynamic Grids, interfacing to several different component frameworks and Grid middlewares. We describe the architecture of the Grid Execution Agent (GEA), the deployment and resource brokering tool of the Grid.it project. GEA has been designed to ease the deployment of complex Grid applications written in a high-level, structured way. To easily handle different component models over heterogeneous Grid resources, the GEA design exploits multiple levels of abstraction. Our approach allows consistent translation of the high-level requirements from heterogeneous, multi-component applications, to low-level operations over different middlewares. GEA architecture provides a unified interface with services to locate resources, devise initial mapping, and instantiate applications, and it is extensible to new component models. It supports dynamically reconfiguring, self-adapting applications by allowing execution-time resource allocation changes.

One of the most promising technical innovations in present-day computing is the invention of grid technologies which harness the computational power of widely distributed collections of computers. However, the programming and optimisation burden of a low level approach to grid computing is clearly unacceptable for large scale, complex applications. The development of grid applications can be simplified by using high-level programming environments. In the present work, we address the problem of the mapping of a high-level grid application onto the computational resources. In order to optimise the mapping of the application, we propose to automatically generate performance models from the application using the process algebra PEPA. We target in this work applications written with the high-level environment ASSIST, since the use of such a structured environment allows us to automate the study of the application more effectively.

International audience; Solving systems of linear equations is one of the key operations in linear algebra. Many different algorithms are available in that purpose. These algorithms require a very accurate tuning to minimise runtime and memory consumption. The TLSE project provides, on one hand, a scenario-driven expert site to help users choose the right algorithm according to their problem and tune accurately this algorithm, and, on the other hand, a test-bed for experts in order to compare algorithms and define scenarios for the expert site. Both features require to run the available solvers a large number of times with many different values for the control parameters (and maybe with many different architectures). Currendy, only the grid can provide enough computing power for this kind of application. The DIET middleware is the GRID backbone for TLSE. It manages the solver services and their scheduling in a scalable way.

Pervasive and on-demand computing are now a reality, mainly in the scientific area, and the computational Grid concept is gaining popularity as a scalable way to deliver access to a wide range of distributed computing and data resources. But, as Grids move from an experimental phase to real production and their deployment in the Internet significantly increases, controlling the security of a Grid application becomes imperative. The most significant Grid security issue is that the different sites composing the Grid will generally be managed by different organizations each with their own security mechanisms and policies. This makes any communication security arrangement on the entities participating to the Grid generally more difficult than if they were on the same local area network. In this paper, we show how the security and privacy services offered by scalable on-demand layer-2 MPLS VPN services can be applied in large-scale Grid scenarios and propose a novel network resource abstraction for discovery and setup of on-demand layer-2 Virtual Private Networks. It has been implemented in a Grid Information Service prototype which was successfully tested on a dedicated testbed infrastructure.

The technology and performance improvements of computational architectures and communication infrastructure, together with the increase of the demand for a greater and more easily usable computing power, generate new sophisticated requirements for distributed application development. The methodologies, infrastructures and tools traditionally used to develop distributed applications disclose a variety of limitations when applied to these new and evolving scenarios. The goal of this minisymposium is to investigate these issues, presenting some innovative approaches in managing the complexity in the design, development and performance analysis of distributed systems. Papers included in this minisymposium primary face the challenges of using the computing Grids as a commonly accepted general purpose computing platform, but the focus is also on paradigms and tools to support the programmers in developing efficient parallel solutions using MPI and OpenMP libraries. Furthermore, particular emphasis is given to some significant aspects of industrial and commercial distributed applications such as, the mobility, the dependability and the security.

This paper introduces a new mechanism for specifying constraints in distributed workflows. By introducing constraints in a contextual form, it is shown how different people and groups within collaborative communities can cooperatively constrain workflows. A comparison with existing state-of-the-art workflow systems is made. These ideas are explored in practice with an illustrative example from High Energy Physics., 19 pages, 5 figures; Submitted to Concurrency and Computation: Practice and Experience for the Special Issue on Workflows at GGF10, cpe859

Ibis is a programming environment for the development of grid applications in Java. We aim to support a wide range of applications and parallel platforms, so our example programs should also go beyond small benchmarks. In this paper we describe a number of larger applications we have developed to evaluate Ibis' suitability for writing grid applications: a cellular automata simulator, a solver for the Satisfiability problem, and grammar-based text analysis. We give an overview of the applications, we describe their implementation, and we show performance results on a number of parallel platforms, ranging from a large supercomputer cluster to a real global grid testbed. Since all of these applications require communication between the processors during execution, it is not surprising that a supercomputer cluster proved to be the most effective platform. However, all of our applications were also efficient on a wide-area cluster system, and some of them even on a grid testbed. Since grid systems are usually only used for trivially parallel systems, we consider these results an encouraging sign that Ibis is indeed an effective environment for grid computing. In particular because for two of the three of the applications the parallelisation required very little additional program code.

International audience; Today's computational grids are using the standard IP routing functionality, that has basically remained unchanged for 2 decades, considering the network as a pure communication infrastructure. With the grid's distributed system point of view, one might consider to extend the commodity Internefs basic functionalities. Higher value functionalities can thus be offered to computational grids. In this paper, we report on our early experiences in building application-aware components and in denning an active grid architecture that would bring the usage of computational grid to a higher level than it is now (mainly batch submission of jobs). To illustrate the potential of this approach, we first present how such application-aware components could be built and then some experiments on deploying enhanced communication services for the grid. We will show how reliable multicast and QoS mechanisms could deploy specific services based on the grid application needs. \textcopyright 2004 Elsevier B.V. All rights reserved.

This paper describes and summarizes the current state of the development for making the Virtual Control Laboratory (VCLab) a GRID application within the ELeGI project. It introduces shortly into GRID techniques and shows how this GRIDifying process is performed to offer virtual scientific experiments (VSE) on the GRID. The architecture and some technical details of the prototype implementation are presented. The next steps in the development are outlined concerning the collaboration aspects of conducting VSEs. The authoring of VSEs is sketched by some proposals of authoring tools. A vision into the future emphasizes the VCLab as a component in a learning environment with a new learning paradigm.

We show in this paper how to evaluate the performance of skeleton-based high level parallel programs. Since many applications fol- low some commonly used algorithmic skeletons, we identify such skele- tons and model them with process algebra in order to get relevant in- formation about the performance of the application, and be able to take some "good" scheduling decisions. This concept is illustrated through the case study of the Pipeline skeleton, and a tool which generates auto- matically a set of models and solves them is presented. Some numerical results are provided, proving the efficiency of this approach.

Grid technology is widely emerging. Still, there is an eminent shortage of real Grid users, mostly due to the lack of a “critical mass” of widely deployed and reliable higher-level Grid services, tailored to application needs. The GridLab project aims to provide fundamentally new capabilities for applications to exploit the power of Grid computing, thus bridging the gap between application needs and existing Grid middleware. We present an overview of GridLab, a large-scale, EU-funded Grid project spanning over a dozen groups in Europe and the US. We first outline our vision of Grid-empowered applications and then discuss GridLab’s general architecture and its Grid Application Toolkit (GAT). We illustrate how applications can be Grid-enabled with the GAT and discuss GridLab’s scheduler as an example of GAT services.

ASSISTCONF is a GUI written in Java that allows users to configure and execute an ASSIST application on Globus-based Grids. 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 network computers, and computational Grids. ASSISTCONF hides the structure of the grid used to the programmer and integrates the ASSIST RTS with the Globus middleware. ASSISTCONF main functionalities are aimed to: . select the computational resources needed to run an application, . configure an ASSIST application by setting the parallelism degree of parallel modules and the number of instances of a replicated module, . assist the user to establish a mapping of the various modules on the selected computational resources, . stage on the selected computational resources the libraries, executable modules, and input files needed to run the ASSIST application, . activate the execution of the executable modules, . transfer the output files to the user machines and delete, if required, all the files used to run the application from the machines used.

In this work we investigate network models that can be potentially employed in the simulation of scheduling algorithms for distributed computing applicati- ons. We seek to develop a model of TCP communication which is both high-level and realistic. Previous research works show that accurate and global modeling of wide-area networks, such as the Internet, faces a number of challenging issues. However, some global models of fairness and bandwidth-s- haring exist, and can be link with the behavior of TCP. Using both previous results and simulation (with NS), we attempt to understand the macroscopic behavior of TCP communications. We then propose a global model of the network for the Grid platform. We perform partial validation of this model in simulation. The model leads to an algorithm for computing bandwidth-sharing. This algorithm can then be implemented as part of Grid application simulations. We provide such an implementation for the simulation toolkit.

International audience; Grid computing is a promising way to aggregate geographically distant machines and to allow them to work together to solve large problems. After studying Grid network requirements, we observe that the network must take part of the Grid computing session to provide intelligent adaptative transport of Grid data streams. By proposing new intelligent dynamic services, active network can be the perfect companion to easily and efficiently deploy and maintain Grid environments and applications. This paper presents the Active Grid Architecture (A-Grid) which focus on active networks adaptation for supporting Grid environments and applications. We focus the benefit of active networking for the grid on three aspects: High performance and dynamic active services, Active Reliable Multicast, and Active Quality of Service. \textcopyright Springer-Verlag Berlin Heidelberg 2001.

"Grid" computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and, in some cases, high-performance orientation. In this article, we define this new field. First, we review the "Grid problem," which we define as flexible, secure, coordinated resource sharing among dynamic collections of individuals, institutions, and resources-what we refer to as virtual organizations. In such settings, we encounter unique authentication, authorization, resource access, resource discovery, and other challenges. It is this class of problem that is addressed by Grid technologies. Next, we present an extensible and open Grid architecture, in which protocols, services, application programming interfaces, and software development kits are categorized according to their roles in enabling resource sharing. We describe requirements that we believe any such mechanisms must satisfy, and we discuss the central role played by the intergrid protocols that enable interoperability among different Grid systems. Finally, we discuss how Grid technologies relate to other contemporary technologies, including enterprise integration, application service provider, storage service provider, and peer-to-peer computing. We maintain that Grid concepts and technologies complement and have much to contribute to these other approaches., 24 pages, 5 figures

In this paper we describe a library layered on top of basic Globus services. The library provides high level services, can be used to develop both web-based and desktop grid applications, it is relatively small and very easy to use. We show its usefulness in the context of a web-based Grid Resource Broker developed using the library as a building block, and in the context of a metacomputing experiment demonstrated at the SuperComputing 2000 conference.