104 resultados para Grid connected PV system


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This paper addresses the problem of performance analysis based on the communication modeling of large-scale heterogeneous distributed systems, with an emphasis on enterprise Grid computing systems. The study of communication layers is important, as the overall performance of a distributed system often critically hinges on the effectiveness of this part. We propose an analytical model that is based on probabilistic analysis and queuing networks. The proposed model considers the processor as well as network heterogeneity of the enterprise Grid system. The model is validated through comprehensive simulations, which demonstrate that the proposed model exhibits a good degree of accuracy for various system sizes, and under different working conditions.

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Abscisic acid (ABA) has been implicated in determining the outcome of interactions between many plants and their pathogens. We had previously shown that increased concentrations of ABA within leaves of Arabidopsis induced susceptibility towards an avirulent strain of Pseudomonas syringae pathovar (pv.) tomato. We now show that ABA induces susceptibility via suppression of the accumulation of components crucial for a resistance response. Lignin and salicylic acid concentrations in leaves were increased during a resistant interaction but reduced when plants were treated with ABA. The reduction in lignin and salicylic acid production was independent of the development of the hypersensitive response (HR), indicating that, in this host-pathogen system, HR is not required for resistance. Genome-wide gene expression analysis using microarrays showed that treatment with ABA suppressed the expression of many defence-related genes, including those important for phenylpropanoid biosynthesis and those encoding resistance-related proteins. Together, these results show that resistance induction in Arabidopsis to an avirulent strain of P. syringae pv. tomato is regulated by ABA.

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This paper addresses the problem of performance analysis based on communication modelling of largescale heterogeneous distributed systems with emphases on enterprise grid computing systems. The study of communication layers is important because the overall performance of a distributed system is often critically hinged on the effectiveness of this part. This model considers processor as well as network heterogeneity of target system. The model is validated through comprehensive simulation, which demonstrates that the proposed model exhibits a good degree of accuracy for various system sizes and under different working conditions. The proposed model is then used to investigate the performance analysis of typical systems.

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This paper addresses the problem of performance modeling of large-scale heterogeneous distributed systems with emphases on enterprise grid computing systems. To this end, we present an analytical model that can be employed to explore the effectiveness of different design approaches so that one can have an intelligent choice during design and evaluation a cost-effective large-scale heterogeneous distributed computing system. The model is validated through comprehensive simulation.

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This paper outlines the development project for the 'Productive on-line student support system', a student "self-help" system, at Deakin University. The aim of this project was to provide Deakin primary teacher education students with a web-based learning tool that allowed them to assess and diagnose their strengths and weaknesses in mathematics, and supports students in their mathematics learning, and in so doing produce mathematically competent graduates. This project was, like similar programs, a development of peer or cross-age tutoring common in primary and secondary schools. A grant under the Deakin University Strategic Teaching and Learning Grant Scheme enabled a staff team from the mathematics education group, to develop a sophisticated and well-designed system that catered for a wide range of student needs, provided useful feedback, and was engaging and easy to use. The under-pinning software for the system was WebCT, available to staff through the Deakin Studies On-line system, to which students are connected also. The 'Productive on-line student support system' enabled students to determine their own mathematical needs, and have these addressed whenever they wished, as often as they wished, and allowed self-monitoring of progress. An outline of the system and examples of the assessment materials will be presented.

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Access to electrification in rural areas of East Timor is extremely limited with as few as 5% of rural households connected to electricity. The government of East Timor intends to increase rural access to electricity significantly in the coming decade. The introduction of small PV systems is envisaged for many households in the most remote areas. Several agencies have piloted the introduction of small solar home systems (SHS) and solar lanterns. In the Railaco sub-district of East Timor, some 1000 households have experience of using either SHS and/or solar lanterns and are in a unique position to indicate a preference regarding these forms of PV lighting technology. This paper reports on a survey of 76 households in Railaco investigating experience with PV lighting systems. Results of the survey indicate a strong preference by users for SHS rather than lanterns. The preference for SHS arose from a range of factors including: a perception of better light quality; ability to illuminate the whole house; reduced risk of damage to the PV equipment; and longer duration of nightly operation. The research indicates that where a single PV lighting system is provided, users are likely to prefer SHS to solar lanterns.

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Grid Web Services are still relevantly a new to business systems, and as more systems are being attached to it, any threat to it could bring collapse and huge harm. Some of these potential threats to Grid Web services come in a new form of a new denial of service attack (DoS), called XML Denial of Service or XDOS attacks. Though, as yet, there have not been any reported attacks from the media, we have observed these attacks are actually far less complex to implement than any previous Denial of Service (DoS), but still just as affective. Current security applications for grid web services (WS-Security for example), based on our observations, and are not up to job of handling the problem. In this paper, we build on our previous work called Service Oriented Traceback Architecture (SOTA), and apply our model to Grid Networks that employ web services. We further introduce a filter defence system, called XDetector, to work in combination with SOTA. Our results show that SOTA in conjunction with XDetector makes for an effective defence against XDoS attacks and upcoming DXDoS.

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In an enterprise grid computing environments, users have access to multiple resources that may be distributed geographically. Thus, resource allocation and scheduling is a fundamental issue in achieving high performance on enterprise grid computing. Most of current job scheduling systems for enterprise grid computing provide batch queuing support and focused solely on the allocation of processors to jobs. However, since I/O is also a critical resource for many jobs, the allocation of processor and I/O resources must be coordinated to allow the system to operate most effectively. To this end, we present a hierarchical scheduling policy paying special attention to I/O and service-demands of parallel jobs in homogeneous and heterogeneous systems with background workload. The performance of the proposed scheduling policy is studied under various system and workload parameters through simulation. We also compare performance of the proposed policy with a static space–time sharing policy. The results show that the proposed policy performs substantially better than the static space–time sharing policy.

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The agent paradigm has been successfully used in a large number of research areas. MAPFS, a parallel file system, constitutes one successful application of agents to the I/O field, providing a multiagent I/O architecture. The use of a multiagent system implies coordination and cooperation among its agents. MAPFS is oriented to clusters of workstations, where agents are applied in order to provide features such as caching or prefetching. The adaptation of MAPFS to a grid environment is named MAPFS-Grid. Agents can help to increase the performance of data-intensive applications running on top of the grid.

This paper describes the conceptual agent framework and the communication model used in MAPFS-Grid, which provides the management of data resources in a grid environment. The evaluation of our proposal shows the advantages of using agents in a data grid.

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This paper addresses a resource selection problem for applications that update data in enterprise grid systems. The problem is insufficiently addressed as most of the existing resource selection approaches in grid environments primarily deal with read-only job. We propose a simple yet efficient algorithm that deals with the complexity of resource selection problem in enterprise grid systems. The problem is formulated as a Multi Criteria Decision Making (MCDM) problem. Our proposed algorithm hides the complexity of resource selection process without neglecting important components that affect job response time. The difficulty on estimating job response time is captured by representing them in terms of different QoS criteria levels at each resource. Our experiments show that the proposed algorithm achieves very good results with good system performance as compared to existing algorithms.

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Offline handwritten recognition is more challenging as indicated by the recognition technologies. This study demonstrates significantly higher rates recognition when compared with other comparable studies. In this paper, we present a circular grid zoning method applied on Polar transformation recognition system. It compares the circular grid zoning (CGZ) and standard zoning (SZ) feature extraction method on Polar and Cartesian coordinate system. We report recognition rates of 92.3%, which are considerably higher than previous studies of zoning based Polar transformation system (86.6%) and zoning based Cartesian recognition system (80.6%). Based on the finding, we propose that our circular grid zoning based Polar transformation system may provide improved classification rates for complex offline handwritten recognition.

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Farmers living in rural villages of Sri Lanka do not have proper access to information to make informed decisions about their livelihoods and as a result they face constant hardships in their lives. They use mobile phones to communicate but these are not currently connected to the Internet. We are investigating how to provide personalized information to farmers with the aim of empowering them to make informed decisions and take appropriate actions. In this paper we propose an empowerment model that has been designed to achieve their goals which have been identified using a scenario-based approach. The model examines several empowerment processes and supporting tools that would help them to achieve their goals with the hope that they would have an increased sense of control, self-efficacy, knowledge and competency. This empowerment model is applied to the development of a mobile based information system that is being developed by an international collaborative research group to address the issues of the farmers.

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Grid transaction management aims at guaranteeing the system consistency in face of various failures in Grid environments. In this paper, we propose a Grid transaction service (GridTS) and design coordination mechanisms for atomic, long-lived and real-time Grid transactions respectively, based on the features of Grid environments. GridTS has the following three advantages. Firstly, it separates the transaction management unit with transaction coordination algorithms so that it can coordinate the above three categories of transactions in a uniform way. Secondly, GridTS can dynamically generate compensating transactions during the long-lived transaction processing. Finally, it provides the programming interfaces similar to traditional distributed transactions. Moreover, we implement a Grid transaction development kit (GridTDK) for application programmers based on our GridTS. We evaluate the feasibility and effectiveness of GridTS by developing an application system using our GridTDK. ©2012 CRL Publishing Ltd.

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All over the world, electrical power systems are encountering radical change stimulated by the urgent need to decarbonize electricity supply, to swap aging resources and to make effective application of swiftly evolving information and communication technologies (ICTs). All of these goals converge toward one direction; ‘Smart Grid.’ The Smart Grid can be described as the transparent, seamless, and instantaneous two-way delivery of energy information, enabling the electricity industry to better manage energy delivery and transmission and empowering consumers to have more control over energy decisions. Basically, the vision of Smart Grid is to provide much better visibility to lower-voltage networks as well as to permit the involvement of consumers in the function of the power system, mostly through smart meters and Smart Homes. A Smart Grid incorporates the features of advanced ICTs to convey real-time information and facilitate the almost instantaneous stability of supply and demand on the electrical grid. The operational data collected by Smart Grid and its sub-systems will allow system operators to quickly recognize the best line of attack to protect against attacks, susceptibility, and so on, sourced by a variety of incidents. However, Smart Grid initially depends upon knowing and researching key performance components and developing the proper education program to equip current and future workforce with the knowledge and skills for exploitation of this greatly advanced system. The aim of this chapter is to provide a basic discussion of the Smart Grid concept, evolution and components of Smart Grid, environmental impacts of Smart Grid and then in some detail, to describe the technologies that are required for its realization. Even though the Smart Grid concept is not yet fully defined, the chapter will be helpful in describing the key enabling technologies and thus allowing the reader to play a part in the debate over the future of the Smart Grid. The chapter concludes with the experimental description and results of developing a hybrid prediction method for solar power which is applicable to successfully implement the ‘Smart Grid.’