Economic Model Predictive Control for Large-Scale and Distributed Energy Systems

DEFF Research Database (Denmark)

Standardi, Laura

Sources (RESs) in the smart grids is increasing. These energy sources bring uncertainty to the production due to their fluctuations. Hence,smart grids need suitable control systems that are able to continuously balance power production and consumption.  We apply the Economic Model Predictive Control (EMPC......) strategy to optimise the economic performances of the energy systems and to balance the power production and consumption. In the case of large-scale energy systems, the electrical grid connects a high number of power units. Because of this, the related control problem involves a high number of variables......In this thesis, we consider control strategies for large and distributed energy systems that are important for the implementation of smart grid technologies.  An electrical grid has to ensure reliability and avoid long-term interruptions in the power supply. Moreover, the share of Renewable Energy...

Suggested Grid Code Modifications to Ensure Wide-Scale Adoption of Photovoltaic Energy in Distributed Power Generation Systems

DEFF Research Database (Denmark)

Yang, Yongheng; Enjeti, Prasad; Blaabjerg, Frede

2013-01-01

Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults. However, in case of a wide-scale penetration of single......-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy...... and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for single-phase PV power systems under grid faults along with reactive power injection is studied in this paper. Three...

Power Flow Distribution Strategy for Improved Power Electronics Energy Efficiency in Battery Storage Systems: Development and Implementation in a Utility-Scale System

Directory of Open Access Journals (Sweden)

Michael Schimpe

2018-03-01

Full Text Available Utility-scale battery storage systems typically consist of multiple smaller units contributing to the overall power dispatch of the system. Herein, the power distribution among these units is analyzed and optimized to operate the system with increased energy efficiency. To improve the real-life storage operation, a holistic system model for battery storage systems has been developed that enables a calculation of the energy efficiency. A utility-scale Second-Life battery storage system with a capacity of 3.3 MWh/3 MW is operated and evaluated in this work. The system is in operation for the provision of primary control reserve in combination with intraday trading for controlling the battery state of charge. The simulation model is parameterized with the system data. Results show that losses in power electronics dominate. An operational strategy improving the energy efficiency through an optimized power flow distribution within the storage system is developed. The power flow distribution strategy is based on the reduction of the power electronics losses at no-load/partial-load by minimizing their in-operation time. The simulation derived power flow distribution strategy is implemented in the real-life storage system. Field-test measurements and analysis prove the functionality of the power flow distribution strategy and reveal the reduction of the energy throughput of the units by 7%, as well as a significant reduction of energy losses in the units by 24%. The cost savings for electricity over the system’s lifetime are approximated to 4.4% of its investment cost.

Rucio - The next generation of large scale distributed system for ATLAS Data Management

CERN Document Server

Garonne, V; The ATLAS collaboration; Beermann, T; Goossens, L; Lassnig, M; Nairz, A; Stewart, GA; Vigne, V; Serfon, C

2013-01-01

Rucio is the next-generation Distributed Data Management(DDM) system benefiting from recent advances in cloud and "Big Data" computing to address HEP experiments scaling requirements. Rucio is an evolution of the ATLAS DDM system Don Quijote 2 (DQ2), which has demonstrated very large scale data management capabilities with more than 140 petabytes spread worldwide across 130 sites, and accesses from 1,000 active users. However, DQ2 is reaching its limits in terms of scalability, requiring a large number of support staff to operate and being hard to extend with new technologies. Rucio will address these issues by relying on a conceptual data model and new technology to ensure system scalability, address new user requirements and employ new automation framework to reduce operational overheads. We present the key concepts of Rucio, including its data organization/representation and a model of how ATLAS central group and user activities will be managed. The Rucio design, and the technology it employs, is described...

Rucio - The next generation of large scale distributed system for ATLAS Data Management

CERN Document Server

Garonne, V; The ATLAS collaboration; Beermann, T; Goossens, L; Lassnig, M; Nairz, A; Stewart, GA; Vigne, V; Serfon, C

2014-01-01

Rucio is the next-generation Distributed Data Management(DDM) system benefiting from recent advances in cloud and ”Big Data” computing to address HEP experiments scaling requirements. Rucio is an evolution of the ATLAS DDM system Don Quijote 2 (DQ2), which has demonstrated very large scale data management capabilities with more than 140 petabytes spread worldwide across 130 sites, and accesses from 1,000 active users. However, DQ2 is reaching its limits in terms of scalability, requiring a large number of support staff to operate and being hard to extend with new technologies. Rucio will address these issues by relying on a conceptual data model and new technology to ensure system scalability, address new user requirements and employ new automation framework to reduce operational overheads. We present the key concepts of Rucio, including its data organization/representation and a model of how ATLAS central group and user activities will be managed. The Rucio design, and the technology it employs, is descr...

Rucio - The next generation of large scale distributed system for ATLAS Data Management

Science.gov (United States)

Garonne, V.; Vigne, R.; Stewart, G.; Barisits, M.; eermann, T. B.; Lassnig, M.; Serfon, C.; Goossens, L.; Nairz, A.; Atlas Collaboration

2014-06-01

Rucio is the next-generation Distributed Data Management (DDM) system benefiting from recent advances in cloud and "Big Data" computing to address HEP experiments scaling requirements. Rucio is an evolution of the ATLAS DDM system Don Quijote 2 (DQ2), which has demonstrated very large scale data management capabilities with more than 140 petabytes spread worldwide across 130 sites, and accesses from 1,000 active users. However, DQ2 is reaching its limits in terms of scalability, requiring a large number of support staff to operate and being hard to extend with new technologies. Rucio will deal with these issues by relying on a conceptual data model and new technology to ensure system scalability, address new user requirements and employ new automation framework to reduce operational overheads. We present the key concepts of Rucio, including its data organization/representation and a model of how to manage central group and user activities. The Rucio design, and the technology it employs, is described, specifically looking at its RESTful architecture and the various software components it uses. We show also the performance of the system.

Ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system.

Science.gov (United States)

Regan, John M; Harrington, Gregory W; Noguera, Daniel R

2002-01-01

Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammonia oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay.

Workflow management in large distributed systems

International Nuclear Information System (INIS)

Legrand, I; Newman, H; Voicu, R; Dobre, C; Grigoras, C

2011-01-01

The MonALISA (Monitoring Agents using a Large Integrated Services Architecture) framework provides a distributed service system capable of controlling and optimizing large-scale, data-intensive applications. An essential part of managing large-scale, distributed data-processing facilities is a monitoring system for computing facilities, storage, networks, and the very large number of applications running on these systems in near realtime. All this monitoring information gathered for all the subsystems is essential for developing the required higher-level services—the components that provide decision support and some degree of automated decisions—and for maintaining and optimizing workflow in large-scale distributed systems. These management and global optimization functions are performed by higher-level agent-based services. We present several applications of MonALISA's higher-level services including optimized dynamic routing, control, data-transfer scheduling, distributed job scheduling, dynamic allocation of storage resource to running jobs and automated management of remote services among a large set of grid facilities.

Workflow management in large distributed systems

Science.gov (United States)

Legrand, I.; Newman, H.; Voicu, R.; Dobre, C.; Grigoras, C.

2011-12-01

The MonALISA (Monitoring Agents using a Large Integrated Services Architecture) framework provides a distributed service system capable of controlling and optimizing large-scale, data-intensive applications. An essential part of managing large-scale, distributed data-processing facilities is a monitoring system for computing facilities, storage, networks, and the very large number of applications running on these systems in near realtime. All this monitoring information gathered for all the subsystems is essential for developing the required higher-level services—the components that provide decision support and some degree of automated decisions—and for maintaining and optimizing workflow in large-scale distributed systems. These management and global optimization functions are performed by higher-level agent-based services. We present several applications of MonALISA's higher-level services including optimized dynamic routing, control, data-transfer scheduling, distributed job scheduling, dynamic allocation of storage resource to running jobs and automated management of remote services among a large set of grid facilities.

Influence of water quality on nitrifier regrowth in two full-scale drinking water distribution systems.

Science.gov (United States)

Scott, Daniel B; Van Dyke, Michele I; Anderson, William B; Huck, Peter M

2015-12-01

The potential for regrowth of nitrifying microorganisms was monitored in 2 full-scale chloraminated drinking water distribution systems in Ontario, Canada, over a 9-month period. Quantitative PCR was used to measure amoA genes from ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), and these values were compared with water quality parameters that can influence nitrifier survival and growth, including total chlorine, ammonia, temperature, pH, and organic carbon. Although there were no severe nitrification episodes, AOB and AOA were frequently detected at low concentrations in samples collected from both distribution systems. A culture-based presence-absence test confirmed the presence of viable nitrifiers. AOB were usually present in similar or greater numbers than AOA in both systems. As well, AOB showed higher regrowth potential compared with AOA in both systems. Statistically significant correlations were measured between several water quality parameters of relevance to nitrification. Total chlorine was negatively correlated with both nitrifiers and heterotrophic plate count (HPC) bacteria, and ammonia levels were positively correlated with nitrifiers. Of particular importance was the strong correlation between HPC and AOB, which reinforced the usefulness of HPC as an operational parameter to measure general microbiological conditions in distribution systems.

Full scale lightning surge tests of distribution transformers and secondary systems

International Nuclear Information System (INIS)

Goedde, G.L.; Dugan, R.C. Sr.; Rowe, L.D.

1992-01-01

This paper reports that low-side surges are known to cause failures of distribution transformers. They also subject load devices to overvoltages. A full-scale model of a residential service has been set up in a laboratory and subjected to impulses approximating lightning strokes. The tests were made to determine the impulse characteristics of the secondary system and to test the validity of previous analyses. Among the variables investigated were stroke location, the balance of the surges in the service cable, and the effectiveness of arrester protection. Low-side surges were found to consist of two basic components: the natural frequency of the system and the inductive response of the system to the stoke current. The latter component is responsible for transformer failures while the former may be responsible for discharge spots often found around secondary bushings. Arresters at the service entrance are effective in diverting most of the energy from a lightning strike, but may not protect sensitive loads. Additional local protection is also needed. The tests affirmed previous simulations and uncovered additional phenomena as well

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems.

Science.gov (United States)

Albattat, Ali; Gruenwald, Benjamin C; Yucelen, Tansel

2016-08-16

The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches.

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems

Directory of Open Access Journals (Sweden)

Ali Albattat

2016-08-01

Full Text Available The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems. These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches.

Mitigation of methane emissions in a pilot-scale biocover system at the av miljø landfill, denmark: system design and gas distribution

DEFF Research Database (Denmark)

Kjeldsen, Peter; Skov, B.; Cassini, Filippo

2013-01-01

-passive biocover system was constructed at the AV Miljø landfill. The biocover is fed by landfill gas pumped out of three leachate wells. An innovative gas distribution system was used to overcome the often observed overloaded hot spot areas resulting from uneven gas distribution to the active methane oxidation......Greenhouse gas mitigation at landfills by methane oxidation in engineered biocover systems is believed to be a cost effective technology but so far a full quantitative evaluation of the efficiency of the technology in full scale has only been carried out in a few cases. A third generation semi...... layer. Performed screening of methane and carbon dioxide concentration at the surface of the biocover showed homogenous distributions indicating an even gas distribution. This was supported by result from a performed tracer test where the compound HFC-134a was added to the gas inlet over a 12 day period...

Large-Scale Cooperative Task Distribution on Peer-to-Peer Networks

Science.gov (United States)

2012-01-01

SUBTITLE Large-scale cooperative task distribution on peer-to-peer networks 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...disadvantages of ML- Chord are its fixed size (two layers), and limited scala - bility for large-scale systems. RC-Chord extends ML- D. Karrels et al...configurable before runtime. This can be improved by incorporating a distributed learning algorithm to tune the number and range of the DLoE tracking

Rucio – The next generation of large scale distributed system for ATLAS data management

International Nuclear Information System (INIS)

Garonne, V; Vigne, R; Stewart, G; Barisits, M; Eermann, T B; Lassnig, M; Serfon, C; Goossens, L; Nairz, A

2014-01-01

Rucio is the next-generation Distributed Data Management (DDM) system benefiting from recent advances in cloud and 'Big Data' computing to address HEP experiments scaling requirements. Rucio is an evolution of the ATLAS DDM system Don Quijote 2 (DQ2), which has demonstrated very large scale data management capabilities with more than 140 petabytes spread worldwide across 130 sites, and accesses from 1,000 active users. However, DQ2 is reaching its limits in terms of scalability, requiring a large number of support staff to operate and being hard to extend with new technologies. Rucio will deal with these issues by relying on a conceptual data model and new technology to ensure system scalability, address new user requirements and employ new automation framework to reduce operational overheads. We present the key concepts of Rucio, including its data organization/representation and a model of how to manage central group and user activities. The Rucio design, and the technology it employs, is described, specifically looking at its RESTful architecture and the various software components it uses. We show also the performance of the system.

Long-term spatial and temporal microbial community dynamics in a large-scale drinking water distribution system with multiple disinfectant regimes.

Science.gov (United States)

Potgieter, Sarah; Pinto, Ameet; Sigudu, Makhosazana; du Preez, Hein; Ncube, Esper; Venter, Stephanus

2018-08-01

Long-term spatial-temporal investigations of microbial dynamics in full-scale drinking water distribution systems are scarce. These investigations can reveal the process, infrastructure, and environmental factors that influence the microbial community, offering opportunities to re-think microbial management in drinking water systems. Often, these insights are missed or are unreliable in short-term studies, which are impacted by stochastic variabilities inherent to large full-scale systems. In this two-year study, we investigated the spatial and temporal dynamics of the microbial community in a large, full scale South African drinking water distribution system that uses three successive disinfection strategies (i.e. chlorination, chloramination and hypochlorination). Monthly bulk water samples were collected from the outlet of the treatment plant and from 17 points in the distribution system spanning nearly 150 km and the bacterial community composition was characterised by Illumina MiSeq sequencing of the V4 hypervariable region of the 16S rRNA gene. Like previous studies, Alpha- and Betaproteobacteria dominated the drinking water bacterial communities, with an increase in Betaproteobacteria post-chloramination. In contrast with previous reports, the observed richness, diversity, and evenness of the bacterial communities were higher in the winter months as opposed to the summer months in this study. In addition to temperature effects, the seasonal variations were also likely to be influenced by changes in average water age in the distribution system and corresponding changes in disinfectant residual concentrations. Spatial dynamics of the bacterial communities indicated distance decay, with bacterial communities becoming increasingly dissimilar with increasing distance between sampling locations. These spatial effects dampened the temporal changes in the bulk water community and were the dominant factor when considering the entire distribution system. However

Long-Term Bacterial Dynamics in a Full-Scale Drinking Water Distribution System.

Science.gov (United States)

Prest, E I; Weissbrodt, D G; Hammes, F; van Loosdrecht, M C M; Vrouwenvelder, J S

2016-01-01

Large seasonal variations in microbial drinking water quality can occur in distribution networks, but are often not taken into account when evaluating results from short-term water sampling campaigns. Temporal dynamics in bacterial community characteristics were investigated during a two-year drinking water monitoring campaign in a full-scale distribution system operating without detectable disinfectant residual. A total of 368 water samples were collected on a biweekly basis at the water treatment plant (WTP) effluent and at one fixed location in the drinking water distribution network (NET). The samples were analysed for heterotrophic plate counts (HPC), Aeromonas plate counts, adenosine-tri-phosphate (ATP) concentrations, and flow cytometric (FCM) total and intact cell counts (TCC, ICC), water temperature, pH, conductivity, total organic carbon (TOC) and assimilable organic carbon (AOC). Multivariate analysis of the large dataset was performed to explore correlative trends between microbial and environmental parameters. The WTP effluent displayed considerable seasonal variations in TCC (from 90 × 103 cells mL-1 in winter time up to 455 × 103 cells mL-1 in summer time) and in bacterial ATP concentrations (water temperature variations. These fluctuations were not detected with HPC and Aeromonas counts. The water in the network was predominantly influenced by the characteristics of the WTP effluent. The increase in ICC between the WTP effluent and the network sampling location was small (34 × 103 cells mL-1 on average) compared to seasonal fluctuations in ICC in the WTP effluent. Interestingly, the extent of bacterial growth in the NET was inversely correlated to AOC concentrations in the WTP effluent (Pearson's correlation factor r = -0.35), and positively correlated with water temperature (r = 0.49). Collecting a large dataset at high frequency over a two year period enabled the characterization of previously undocumented seasonal dynamics in the distribution

An optimal beam alignment method for large-scale distributed space surveillance radar system

Science.gov (United States)

Huang, Jian; Wang, Dongya; Xia, Shuangzhi

2018-06-01

Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.

Probabilistic analysis in normal operation of distribution system with distributed generation

DEFF Research Database (Denmark)

Villafafila-Robles, R.; Sumper, A.; Bak-Jensen, B.

2011-01-01

Nowadays, the incorporation of high levels of small-scale non-dispatchable distributed generation is leading to the transition from the traditional 'vertical' power system structure to a 'horizontally-operated' power system, where the distribution networks contain both stochastic generation...... and load. This fact increases the number of stochastic inputs and dependence structures between them need to be considered. The deterministic analysis is not enough to cope with these issues and a new approach is needed. Probabilistic analysis provides a better approach. Moreover, as distribution systems...

Long-Term Bacterial Dynamics in a Full-Scale Drinking Water Distribution System

KAUST Repository

Prest, E. I.; Weissbrodt, D. G.; Hammes, F.; Van Loosdrecht, M. C M; Vrouwenvelder, Johannes S.

2016-01-01

Large seasonal variations in microbial drinking water quality can occur in distribution networks, but are often not taken into account when evaluating results from short-term water sampling campaigns. Temporal dynamics in bacterial community characteristics were investigated during a two-year drinking water monitoring campaign in a full-scale distribution system operating without detectable disinfectant residual. A total of 368 water samples were collected on a biweekly basis at the water treatment plant (WTP) effluent and at one fixed location in the drinking water distribution network (NET). The samples were analysed for heterotrophic plate counts (HPC), Aeromonas plate counts, adenosine-tri-phosphate (ATP) concentrations, and flow cytometric (FCM) total and intact cell counts (TCC, ICC), water temperature, pH, conductivity, total organic carbon (TOC) and assimilable organic carbon (AOC). Multivariate analysis of the large dataset was performed to explore correlative trends between microbial and environmental parameters. The WTP effluent displayed considerable seasonal variations in TCC (from 90 × 103 cells mL-1 in winter time up to 455 × 103 cells mL-1 in summer time) and in bacterial ATP concentrations (<1–3.6 ng L-1), which were congruent with water temperature variations. These fluctuations were not detected with HPC and Aeromonas counts. The water in the network was predominantly influenced by the characteristics of the WTP effluent. The increase in ICC between the WTP effluent and the network sampling location was small (34 × 103 cells mL-1 on average) compared to seasonal fluctuations in ICC in the WTP effluent. Interestingly, the extent of bacterial growth in the NET was inversely correlated to AOC concentrations in the WTP effluent (Pearson’s correlation factor r = -0.35), and positively correlated with water temperature (r = 0.49). Collecting a large dataset at high frequency over a two year period enabled the characterization of previously

Long-Term Bacterial Dynamics in a Full-Scale Drinking Water Distribution System.

Directory of Open Access Journals (Sweden)

E I Prest

Full Text Available Large seasonal variations in microbial drinking water quality can occur in distribution networks, but are often not taken into account when evaluating results from short-term water sampling campaigns. Temporal dynamics in bacterial community characteristics were investigated during a two-year drinking water monitoring campaign in a full-scale distribution system operating without detectable disinfectant residual. A total of 368 water samples were collected on a biweekly basis at the water treatment plant (WTP effluent and at one fixed location in the drinking water distribution network (NET. The samples were analysed for heterotrophic plate counts (HPC, Aeromonas plate counts, adenosine-tri-phosphate (ATP concentrations, and flow cytometric (FCM total and intact cell counts (TCC, ICC, water temperature, pH, conductivity, total organic carbon (TOC and assimilable organic carbon (AOC. Multivariate analysis of the large dataset was performed to explore correlative trends between microbial and environmental parameters. The WTP effluent displayed considerable seasonal variations in TCC (from 90 × 103 cells mL-1 in winter time up to 455 × 103 cells mL-1 in summer time and in bacterial ATP concentrations (<1-3.6 ng L-1, which were congruent with water temperature variations. These fluctuations were not detected with HPC and Aeromonas counts. The water in the network was predominantly influenced by the characteristics of the WTP effluent. The increase in ICC between the WTP effluent and the network sampling location was small (34 × 103 cells mL-1 on average compared to seasonal fluctuations in ICC in the WTP effluent. Interestingly, the extent of bacterial growth in the NET was inversely correlated to AOC concentrations in the WTP effluent (Pearson's correlation factor r = -0.35, and positively correlated with water temperature (r = 0.49. Collecting a large dataset at high frequency over a two year period enabled the characterization of previously

Long-Term Bacterial Dynamics in a Full-Scale Drinking Water Distribution System

KAUST Repository

Prest, E. I.

2016-10-28

Large seasonal variations in microbial drinking water quality can occur in distribution networks, but are often not taken into account when evaluating results from short-term water sampling campaigns. Temporal dynamics in bacterial community characteristics were investigated during a two-year drinking water monitoring campaign in a full-scale distribution system operating without detectable disinfectant residual. A total of 368 water samples were collected on a biweekly basis at the water treatment plant (WTP) effluent and at one fixed location in the drinking water distribution network (NET). The samples were analysed for heterotrophic plate counts (HPC), Aeromonas plate counts, adenosine-tri-phosphate (ATP) concentrations, and flow cytometric (FCM) total and intact cell counts (TCC, ICC), water temperature, pH, conductivity, total organic carbon (TOC) and assimilable organic carbon (AOC). Multivariate analysis of the large dataset was performed to explore correlative trends between microbial and environmental parameters. The WTP effluent displayed considerable seasonal variations in TCC (from 90 × 103 cells mL-1 in winter time up to 455 × 103 cells mL-1 in summer time) and in bacterial ATP concentrations (<1–3.6 ng L-1), which were congruent with water temperature variations. These fluctuations were not detected with HPC and Aeromonas counts. The water in the network was predominantly influenced by the characteristics of the WTP effluent. The increase in ICC between the WTP effluent and the network sampling location was small (34 × 103 cells mL-1 on average) compared to seasonal fluctuations in ICC in the WTP effluent. Interestingly, the extent of bacterial growth in the NET was inversely correlated to AOC concentrations in the WTP effluent (Pearson’s correlation factor r = -0.35), and positively correlated with water temperature (r = 0.49). Collecting a large dataset at high frequency over a two year period enabled the characterization of previously

Design of Availability-Dependent Distributed Services in Large-Scale Uncooperative Settings

Science.gov (United States)

Morales, Ramses Victor

2009-01-01

Thesis Statement: "Availability-dependent global predicates can be efficiently and scalably realized for a class of distributed services, in spite of specific selfish and colluding behaviors, using local and decentralized protocols". Several types of large-scale distributed systems spanning the Internet have to deal with availability variations…

An Applet-based Anonymous Distributed Computing System.

Science.gov (United States)

Finkel, David; Wills, Craig E.; Ciaraldi, Michael J.; Amorin, Kevin; Covati, Adam; Lee, Michael

2001-01-01

Defines anonymous distributed computing systems and focuses on the specifics of a Java, applet-based approach for large-scale, anonymous, distributed computing on the Internet. Explains the possibility of a large number of computers participating in a single computation and describes a test of the functionality of the system. (Author/LRW)

A Topology Visualization Early Warning Distribution Algorithm for Large-Scale Network Security Incidents

Directory of Open Access Journals (Sweden)

Hui He

2013-01-01

Full Text Available It is of great significance to research the early warning system for large-scale network security incidents. It can improve the network system’s emergency response capabilities, alleviate the cyber attacks’ damage, and strengthen the system’s counterattack ability. A comprehensive early warning system is presented in this paper, which combines active measurement and anomaly detection. The key visualization algorithm and technology of the system are mainly discussed. The large-scale network system’s plane visualization is realized based on the divide and conquer thought. First, the topology of the large-scale network is divided into some small-scale networks by the MLkP/CR algorithm. Second, the sub graph plane visualization algorithm is applied to each small-scale network. Finally, the small-scale networks’ topologies are combined into a topology based on the automatic distribution algorithm of force analysis. As the algorithm transforms the large-scale network topology plane visualization problem into a series of small-scale network topology plane visualization and distribution problems, it has higher parallelism and is able to handle the display of ultra-large-scale network topology.

On-line detection of Escherichia coli intrusion in a pilot-scale drinking water distribution system.

Science.gov (United States)

Ikonen, Jenni; Pitkänen, Tarja; Kosse, Pascal; Ciszek, Robert; Kolehmainen, Mikko; Miettinen, Ilkka T

2017-08-01

Improvements in microbial drinking water quality monitoring are needed for the better control of drinking water distribution systems and for public health protection. Conventional water quality monitoring programmes are not always able to detect a microbial contamination of drinking water. In the drinking water production chain, in addition to the vulnerability of source waters, the distribution networks are prone to contamination. In this study, a pilot-scale drinking-water distribution network with an on-line monitoring system was utilized for detecting bacterial intrusion. During the experimental Escherichia coli intrusions, the contaminant was measured by applying a set of on-line sensors for electric conductivity (EC), pH, temperature (T), turbidity, UV-absorbance at 254 nm (UVAS SC) and with a device for particle counting. Monitored parameters were compared with the measured E. coli counts using the integral calculations of the detected peaks. EC measurement gave the strongest signal compared with the measured baseline during the E. coli intrusion. Integral calculations showed that the peaks in the EC, pH, T, turbidity and UVAS SC data were detected corresponding to the time predicted. However, the pH and temperature peaks detected were barely above the measured baseline and could easily be mixed with the background noise. The results indicate that on-line monitoring can be utilized for the rapid detection of microbial contaminants in the drinking water distribution system although the peak interpretation has to be performed carefully to avoid being mixed up with normal variations in the measurement data. Copyright © 2017 Elsevier Ltd. All rights reserved.

THE MINERALOGY OF PB SCALES IN DRINKING WATER DISTRIBUTION SYSTEMS AS REVEALED BY COMBINED XRD AND MICRO-RAMAN SPECTROSCOPY

Science.gov (United States)

Dissolving Pb from lead service lines and Pb-containing brasses and solders has become a major health issue for many water distribution systems. Knowledge of the mineralogy of scales in these pipes is key to modeling this dissolution. The traditional method of determining their ...

LARGE SCALE DISTRIBUTED PARAMETER MODEL OF MAIN MAGNET SYSTEM AND FREQUENCY DECOMPOSITION ANALYSIS

Energy Technology Data Exchange (ETDEWEB)

ZHANG,W.; MARNERIS, I.; SANDBERG, J.

2007-06-25

Large accelerator main magnet system consists of hundreds, even thousands, of dipole magnets. They are linked together under selected configurations to provide highly uniform dipole fields when powered. Distributed capacitance, insulation resistance, coil resistance, magnet inductance, and coupling inductance of upper and lower pancakes make each magnet a complex network. When all dipole magnets are chained together in a circle, they become a coupled pair of very high order complex ladder networks. In this study, a network of more than thousand inductive, capacitive or resistive elements are used to model an actual system. The circuit is a large-scale network. Its equivalent polynomial form has several hundred degrees. Analysis of this high order circuit and simulation of the response of any or all components is often computationally infeasible. We present methods to use frequency decomposition approach to effectively simulate and analyze magnet configuration and power supply topologies.

Distributed and hierarchical control techniques for large-scale power plant systems

International Nuclear Information System (INIS)

Raju, G.V.S.; Kisner, R.A.

1985-08-01

In large-scale systems, integrated and coordinated control functions are required to maximize plant availability, to allow maneuverability through various power levels, and to meet externally imposed regulatory limitations. Nuclear power plants are large-scale systems. Prime subsystems are those that contribute directly to the behavior of the plant's ultimate output. The prime subsystems in a nuclear power plant include reactor, primary and intermediate heat transport, steam generator, turbine generator, and feedwater system. This paper describes and discusses the continuous-variable control system developed to supervise prime plant subsystems for optimal control and coordination

Distributed weighted least-squares estimation with fast convergence for large-scale systems☆

Science.gov (United States)

Marelli, Damián Edgardo; Fu, Minyue

2015-01-01

In this paper we study a distributed weighted least-squares estimation problem for a large-scale system consisting of a network of interconnected sub-systems. Each sub-system is concerned with a subset of the unknown parameters and has a measurement linear in the unknown parameters with additive noise. The distributed estimation task is for each sub-system to compute the globally optimal estimate of its own parameters using its own measurement and information shared with the network through neighborhood communication. We first provide a fully distributed iterative algorithm to asymptotically compute the global optimal estimate. The convergence rate of the algorithm will be maximized using a scaling parameter and a preconditioning method. This algorithm works for a general network. For a network without loops, we also provide a different iterative algorithm to compute the global optimal estimate which converges in a finite number of steps. We include numerical experiments to illustrate the performances of the proposed methods. PMID:25641976

Low-Concentration Solar-Power Systems based on Organic Rankine Cycles for Distributed-Scale Applications:Overview and Further Developments

Directory of Open Access Journals (Sweden)

Christos N. Markides

2015-12-01

Full Text Available This paper is concerned with the emergence and development of low- to medium-grade thermal-energy conversion systems for distributed power generation based on thermodynamic vapour-phase heat-engine cycles undergone by organic working-fluids, namely organic Rankine cycles (ORCs. ORC power systems are, to some extent, a relatively established and mature technology that is well-suited to converting low-/medium-grade heat (at temperatures up to ~ 300 – 400 °C to useful work, at an output power scale from a few kW to 10s of MW. Thermal efficiencies in excess of 25% are achievable at higher temperatures and larger scales, and efforts are currently in progress to improve the overall economic viability, and thus uptake, of ORC power systems by focusing on advanced architectures, working-fluid selection, heat exchangers and expansion machines. Solar-power systems based on ORC technology have a significant potential to be used for distributed power generation, by converting thermal energy from simple and low-cost non-concentrated or low-concentration collectors to mechanical, hydraulic or electrical energy. Current fields of use include mainly geothermal and biomass/biogas, as well as the recovery and conversion of waste heat, leading to improved energy efficiency, primary energy (i.e. fuel use and emission minimization, yet the technology is highly transferable to solar power generation as an affordable alternative to small- to medium-scale photovoltaic (PV systems. Solar-ORC systems offer naturally the advantages of providing a simultaneous thermal-energy output for hot water provision and/or space heating, and the particularly interesting possibility of relatively straightforward on-site (thermal energy storage. Key performance characteristics are presented, and important heat transfer effects that act to limit performance are identified as noteworthy directions of future research for the further development of this technology.

Low-Concentration Solar-Power Systems Based on Organic Rankine Cycles for Distributed-Scale Applications: Overview and Further Developments

Energy Technology Data Exchange (ETDEWEB)

Markides, Christos N., E-mail: c.markides@imperial.ac.uk [Clean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London (United Kingdom)

2015-12-10

This paper is concerned with the emergence and development of low-to-medium-grade thermal-energy-conversion systems for distributed power generation based on thermodynamic vapor-phase heat-engine cycles undergone by organic working fluids, namely organic Rankine cycles (ORCs). ORC power systems are, to some extent, a relatively established and mature technology that is well-suited to converting low/medium-grade heat (at temperatures up to ~300–400°C) to useful work, at an output power scale from a few kilowatts to 10s of megawatts. Thermal efficiencies in excess of 25% are achievable at higher temperatures and larger scales, and efforts are currently in progress to improve the overall economic viability and thus uptake of ORC power systems, by focusing on advanced architectures, working-fluid selection, heat exchangers and expansion machines. Solar-power systems based on ORC technology have a significant potential to be used for distributed power generation, by converting thermal energy from simple and low-cost non-concentrated or low-concentration collectors to mechanical, hydraulic, or electrical energy. Current fields of use include mainly geothermal and biomass/biogas, as well as the recovery and conversion of waste heat, leading to improved energy efficiency, primary energy (i.e., fuel) use and emission minimization, yet the technology is highly transferable to solar-power generation as an affordable alternative to small-to-medium-scale photovoltaic systems. Solar-ORC systems offer naturally the advantages of providing a simultaneous thermal-energy output for hot water provision and/or space heating, and the particularly interesting possibility of relatively straightforward onsite (thermal) energy storage. Key performance characteristics are presented, and important heat transfer effects that act to limit performance are identified as noteworthy directions of future research for the further development of this technology.

Low-Concentration Solar-Power Systems Based on Organic Rankine Cycles for Distributed-Scale Applications: Overview and Further Developments

International Nuclear Information System (INIS)

Markides, Christos N.

2015-01-01

This paper is concerned with the emergence and development of low-to-medium-grade thermal-energy-conversion systems for distributed power generation based on thermodynamic vapor-phase heat-engine cycles undergone by organic working fluids, namely organic Rankine cycles (ORCs). ORC power systems are, to some extent, a relatively established and mature technology that is well-suited to converting low/medium-grade heat (at temperatures up to ~300–400°C) to useful work, at an output power scale from a few kilowatts to 10s of megawatts. Thermal efficiencies in excess of 25% are achievable at higher temperatures and larger scales, and efforts are currently in progress to improve the overall economic viability and thus uptake of ORC power systems, by focusing on advanced architectures, working-fluid selection, heat exchangers and expansion machines. Solar-power systems based on ORC technology have a significant potential to be used for distributed power generation, by converting thermal energy from simple and low-cost non-concentrated or low-concentration collectors to mechanical, hydraulic, or electrical energy. Current fields of use include mainly geothermal and biomass/biogas, as well as the recovery and conversion of waste heat, leading to improved energy efficiency, primary energy (i.e., fuel) use and emission minimization, yet the technology is highly transferable to solar-power generation as an affordable alternative to small-to-medium-scale photovoltaic systems. Solar-ORC systems offer naturally the advantages of providing a simultaneous thermal-energy output for hot water provision and/or space heating, and the particularly interesting possibility of relatively straightforward onsite (thermal) energy storage. Key performance characteristics are presented, and important heat transfer effects that act to limit performance are identified as noteworthy directions of future research for the further development of this technology.

Scaling analysis of meteorite shower mass distributions

DEFF Research Database (Denmark)

Oddershede, Lene; Meibom, A.; Bohr, Jakob

1998-01-01

Meteorite showers are the remains of extraterrestrial objects which are captivated by the gravitational field of the Earth. We have analyzed the mass distribution of fragments from 16 meteorite showers for scaling. The distributions exhibit distinct scaling behavior over several orders of magnetude......; the observed scaling exponents vary from shower to shower. Half of the analyzed showers show a single scaling region while the orther half show multiple scaling regimes. Such an analysis can provide knowledge about the fragmentation process and about the original meteoroid. We also suggest to compare...... the observed scaling exponents to exponents observed in laboratory experiments and discuss the possibility that one can derive insight into the original shapes of the meteoroids....

The ATLAS Distributed Analysis System

CERN Document Server

Legger, F; The ATLAS collaboration; Pacheco Pages, A; Stradling, A

2013-01-01

In the LHC operations era, analysis of the multi-petabyte ATLAS data sample by globally distributed physicists is a challenging task. To attain the required scale the ATLAS Computing Model was designed around the concept of grid computing, realized in the Worldwide LHC Computing Grid (WLCG), the largest distributed computational resource existing in the sciences. The ATLAS experiment currently stores over 140 PB of data and runs about 140,000 concurrent jobs continuously at WLCG sites. During the first run of the LHC, the ATLAS Distributed Analysis (DA) service has operated stably and scaled as planned. More than 1600 users submitted jobs in 2012, with 2 million or more analysis jobs per week, peaking at about a million jobs per day. The system dynamically distributes popular data to expedite processing and maximally utilize resources. The reliability of the DA service is high but steadily improving; grid sites are continually validated against a set of standard tests, and a dedicated team of expert shifters ...

The ATLAS Distributed Analysis System

CERN Document Server

Legger, F; The ATLAS collaboration

2014-01-01

In the LHC operations era, analysis of the multi-petabyte ATLAS data sample by globally distributed physicists is a challenging task. To attain the required scale the ATLAS Computing Model was designed around the concept of grid computing, realized in the Worldwide LHC Computing Grid (WLCG), the largest distributed computational resource existing in the sciences. The ATLAS experiment currently stores over 140 PB of data and runs about 140,000 concurrent jobs continuously at WLCG sites. During the first run of the LHC, the ATLAS Distributed Analysis (DA) service has operated stably and scaled as planned. More than 1600 users submitted jobs in 2012, with 2 million or more analysis jobs per week, peaking at about a million jobs per day. The system dynamically distributes popular data to expedite processing and maximally utilize resources. The reliability of the DA service is high but steadily improving; grid sites are continually validated against a set of standard tests, and a dedicated team of expert shifters ...

Characteristics of iron corrosion scales and water quality variations in drinking water distribution systems of different pipe materials.

Science.gov (United States)

Li, Manjie; Liu, Zhaowei; Chen, Yongcan; Hai, Yang

2016-12-01

Interaction between old, corroded iron pipe surfaces and bulk water is crucial to the water quality protection in drinking water distribution systems (WDS). Iron released from corrosion products will deteriorate water quality and lead to red water. This study attempted to understand the effects of pipe materials on corrosion scale characteristics and water quality variations in WDS. A more than 20-year-old hybrid pipe section assembled of unlined cast iron pipe (UCIP) and galvanized iron pipe (GIP) was selected to investigate physico-chemical characteristics of corrosion scales and their effects on water quality variations. Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Inductively Coupled Plasma (ICP) and X-ray Diffraction (XRD) were used to analyze micromorphology and chemical composition of corrosion scales. In bench testing, water quality parameters, such as pH, dissolved oxygen (DO), oxidation reduction potential (ORP), alkalinity, conductivity, turbidity, color, Fe 2+ , Fe 3+ and Zn 2+ , were determined. Scale analysis and bench-scale testing results demonstrated a significant effect of pipe materials on scale characteristics and thereby water quality variations in WDS. Characteristics of corrosion scales sampled from different pipe segments show obvious differences, both in physical and chemical aspects. Corrosion scales were found highly amorphous. Thanks to the protection of zinc coatings, GIP system was identified as the best water quality stability, in spite of high zinc release potential. It is deduced that the complicated composition of corrosion scales and structural break by the weld result in the diminished water quality stability in HP system. Measurement results showed that iron is released mainly in ferric particulate form. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distributed intelligent urban environment monitoring system

Science.gov (United States)

Du, Jinsong; Wang, Wei; Gao, Jie; Cong, Rigang

2018-02-01

The current environmental pollution and destruction have developed into a world-wide major social problem that threatens human survival and development. Environmental monitoring is the prerequisite and basis of environmental governance, but overall, the current environmental monitoring system is facing a series of problems. Based on the electrochemical sensor, this paper designs a small, low-cost, easy to layout urban environmental quality monitoring terminal, and multi-terminal constitutes a distributed network. The system has been small-scale demonstration applications and has confirmed that the system is suitable for large-scale promotion

NASA's Information Power Grid: Large Scale Distributed Computing and Data Management

Science.gov (United States)

Johnston, William E.; Vaziri, Arsi; Hinke, Tom; Tanner, Leigh Ann; Feiereisen, William J.; Thigpen, William; Tang, Harry (Technical Monitor)

2001-01-01

Large-scale science and engineering are done through the interaction of people, heterogeneous computing resources, information systems, and instruments, all of which are geographically and organizationally dispersed. The overall motivation for Grids is to facilitate the routine interactions of these resources in order to support large-scale science and engineering. Multi-disciplinary simulations provide a good example of a class of applications that are very likely to require aggregation of widely distributed computing, data, and intellectual resources. Such simulations - e.g. whole system aircraft simulation and whole system living cell simulation - require integrating applications and data that are developed by different teams of researchers frequently in different locations. The research team's are the only ones that have the expertise to maintain and improve the simulation code and/or the body of experimental data that drives the simulations. This results in an inherently distributed computing and data management environment.

Optical interconnect for large-scale systems

Science.gov (United States)

Dress, William

2013-02-01

This paper presents a switchless, optical interconnect module that serves as a node in a network of identical distribution modules for large-scale systems. Thousands to millions of hosts or endpoints may be interconnected by a network of such modules, avoiding the need for multi-level switches. Several common network topologies are reviewed and their scaling properties assessed. The concept of message-flow routing is discussed in conjunction with the unique properties enabled by the optical distribution module where it is shown how top-down software control (global routing tables, spanning-tree algorithms) may be avoided.

Distributed redundancy and robustness in complex systems

KAUST Repository

Randles, Martin

2011-03-01

The uptake and increasing prevalence of Web 2.0 applications, promoting new large-scale and complex systems such as Cloud computing and the emerging Internet of Services/Things, requires tools and techniques to analyse and model methods to ensure the robustness of these new systems. This paper reports on assessing and improving complex system resilience using distributed redundancy, termed degeneracy in biological systems, to endow large-scale complicated computer systems with the same robustness that emerges in complex biological and natural systems. However, in order to promote an evolutionary approach, through emergent self-organisation, it is necessary to specify the systems in an \\'open-ended\\' manner where not all states of the system are prescribed at design-time. In particular an observer system is used to select robust topologies, within system components, based on a measurement of the first non-zero Eigen value in the Laplacian spectrum of the components\\' network graphs; also known as the algebraic connectivity. It is shown, through experimentation on a simulation, that increasing the average algebraic connectivity across the components, in a network, leads to an increase in the variety of individual components termed distributed redundancy; the capacity for structurally distinct components to perform an identical function in a particular context. The results are applied to a specific application where active clustering of like services is used to aid load balancing in a highly distributed network. Using the described procedure is shown to improve performance and distribute redundancy. © 2010 Elsevier Inc.

A comparison of producer gas, biochar, and activated carbon from two distributed scale thermochemical conversion systems used to process forest biomass

Science.gov (United States)

Nathaniel Anderson; J. Greg Jones; Deborah Page-Dumroese; Daniel McCollum; Stephen Baker; Daniel Loeffler; Woodam Chung

2013-01-01

Thermochemical biomass conversion systems have the potential to produce heat, power, fuels and other products from forest biomass at distributed scales that meet the needs of some forest industry facilities. However, many of these systems have not been deployed in this sector and the products they produce from forest biomass have not been adequately described or...

Homogeneity and scale testing of generalized gamma distribution

International Nuclear Information System (INIS)

Stehlik, Milan

2008-01-01

The aim of this paper is to derive the exact distributions of the likelihood ratio tests of homogeneity and scale hypothesis when the observations are generalized gamma distributed. The special cases of exponential, Rayleigh, Weibull or gamma distributed observations are discussed exclusively. The photoemulsion experiment analysis and scale test with missing time-to-failure observations are present to illustrate the applications of methods discussed

8th International Symposium on Intelligent Distributed Computing & Workshop on Cyber Security and Resilience of Large-Scale Systems & 6th International Workshop on Multi-Agent Systems Technology and Semantics

CERN Document Server

Braubach, Lars; Venticinque, Salvatore; Badica, Costin

2015-01-01

This book represents the combined peer-reviewed proceedings of the Eight International Symposium on Intelligent Distributed Computing - IDC'2014, of the Workshop on Cyber Security and Resilience of Large-Scale Systems - WSRL-2014, and of the Sixth International Workshop on Multi-Agent Systems Technology and Semantics- MASTS-2014. All the events were held in Madrid, Spain, during September 3-5, 2014. The 47 contributions published in this book address several topics related to theory and applications of the intelligent distributed computing and multi-agent systems, including: agent-based data processing, ambient intelligence, collaborative systems, cryptography and security, distributed algorithms, grid and cloud computing, information extraction, knowledge management, big data and ontologies, social networks, swarm intelligence or videogames amongst others.

PanDA: distributed production and distributed analysis system for ATLAS

International Nuclear Information System (INIS)

Maeno, T

2008-01-01

A new distributed software system was developed in the fall of 2005 for the ATLAS experiment at the LHC. This system, called PANDA, provides an integrated service architecture with late binding of jobs, maximal automation through layered services, tight binding with ATLAS Distributed Data Management system [1], advanced error discovery and recovery procedures, and other features. In this talk, we will describe the PANDA software system. Special emphasis will be placed on the evolution of PANDA based on one and half year of real experience in carrying out Computer System Commissioning data production [2] for ATLAS. The architecture of PANDA is well suited for the computing needs of the ATLAS experiment, which is expected to be one of the first HEP experiments to operate at the petabyte scale

Dynamic models for transient stability analysis of transmission and distribution systems with distributed generation : an overview

NARCIS (Netherlands)

Boemer, J.C.; Gibescu, M.; Kling, W.L.

2009-01-01

Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large

Large-scale Intelligent Transporation Systems simulation

Energy Technology Data Exchange (ETDEWEB)

Ewing, T.; Canfield, T.; Hannebutte, U.; Levine, D.; Tentner, A.

1995-06-01

A prototype computer system has been developed which defines a high-level architecture for a large-scale, comprehensive, scalable simulation of an Intelligent Transportation System (ITS) capable of running on massively parallel computers and distributed (networked) computer systems. The prototype includes the modelling of instrumented ``smart`` vehicles with in-vehicle navigation units capable of optimal route planning and Traffic Management Centers (TMC). The TMC has probe vehicle tracking capabilities (display position and attributes of instrumented vehicles), and can provide 2-way interaction with traffic to provide advisories and link times. Both the in-vehicle navigation module and the TMC feature detailed graphical user interfaces to support human-factors studies. The prototype has been developed on a distributed system of networked UNIX computers but is designed to run on ANL`s IBM SP-X parallel computer system for large scale problems. A novel feature of our design is that vehicles will be represented by autonomus computer processes, each with a behavior model which performs independent route selection and reacts to external traffic events much like real vehicles. With this approach, one will be able to take advantage of emerging massively parallel processor (MPP) systems.

Distributed Model Predictive Control over Multiple Groups of Vehicles in Highway Intelligent Space for Large Scale System

Directory of Open Access Journals (Sweden)

Tang Xiaofeng

2014-01-01

Full Text Available The paper presents the three time warning distances for solving the large scale system of multiple groups of vehicles safety driving characteristics towards highway tunnel environment based on distributed model prediction control approach. Generally speaking, the system includes two parts. First, multiple vehicles are divided into multiple groups. Meanwhile, the distributed model predictive control approach is proposed to calculate the information framework of each group. Each group of optimization performance considers the local optimization and the neighboring subgroup of optimization characteristics, which could ensure the global optimization performance. Second, the three time warning distances are studied based on the basic principles used for highway intelligent space (HIS and the information framework concept is proposed according to the multiple groups of vehicles. The math model is built to avoid the chain avoidance of vehicles. The results demonstrate that the proposed highway intelligent space method could effectively ensure driving safety of multiple groups of vehicles under the environment of fog, rain, or snow.

Scaling Techniques for Massive Scale-Free Graphs in Distributed (External) Memory

KAUST Repository

Pearce, Roger; Gokhale, Maya; Amato, Nancy M.

2013-01-01

We present techniques to process large scale-free graphs in distributed memory. Our aim is to scale to trillions of edges, and our research is targeted at leadership class supercomputers and clusters with local non-volatile memory, e.g., NAND Flash

Multi-scale dynamical behavior of spatially distributed systems: a deterministic point of view

Science.gov (United States)

Mangiarotti, S.; Le Jean, F.; Drapeau, L.; Huc, M.

2015-12-01

Physical and biophysical systems are spatially distributed systems. Their behavior can be observed or modelled spatially at various resolutions. In this work, a deterministic point of view is adopted to analyze multi-scale behavior taking a set of ordinary differential equation (ODE) as elementary part of the system.To perform analyses, scenes of study are thus generated based on ensembles of identical elementary ODE systems. Without any loss of generality, their dynamics is chosen chaotic in order to ensure sensitivity to initial conditions, that is, one fundamental property of atmosphere under instable conditions [1]. The Rössler system [2] is used for this purpose for both its topological and algebraic simplicity [3,4].Two cases are thus considered: the chaotic oscillators composing the scene of study are taken either independent, or in phase synchronization. Scale behaviors are analyzed considering the scene of study as aggregations (basically obtained by spatially averaging the signal) or as associations (obtained by concatenating the time series). The global modeling technique is used to perform the numerical analyses [5].One important result of this work is that, under phase synchronization, a scene of aggregated dynamics can be approximated by the elementary system composing the scene, but modifying its parameterization [6]. This is shown based on numerical analyses. It is then demonstrated analytically and generalized to a larger class of ODE systems. Preliminary applications to cereal crops observed from satellite are also presented.[1] Lorenz, Deterministic nonperiodic flow. J. Atmos. Sci., 20, 130-141 (1963).[2] Rössler, An equation for continuous chaos, Phys. Lett. A, 57, 397-398 (1976).[3] Gouesbet & Letellier, Global vector-field reconstruction by using a multivariate polynomial L2 approximation on nets, Phys. Rev. E 49, 4955-4972 (1994).[4] Letellier, Roulin & Rössler, Inequivalent topologies of chaos in simple equations, Chaos, Solitons

White Mango Scale, Aulacaspis tubercularis , Distribution and ...

African Journals Online (AJOL)

White Mango Scale, Aulacaspis tubercularis , Distribution and Severity Status in East and West Wollega Zones, ... Among the insect pests attacking mango plant, white mango scale is the most devastating insect pest. ... HOW TO USE AJOL.

Evaluation of corrosion and scaling tendency indices in a drinking water distribution system: a case study of Bandar Abbas city, Iran.

Science.gov (United States)

Alipour, Vali; Dindarloo, Kavoos; Mahvi, Amir Hossein; Rezaei, Leila

2015-03-01

Corrosion and scaling is a major problem in water distribution systems, thus evaluation of water corrosivity properties is a routine test in water networks. To evaluate water stability in the Bandar Abbas water distribution system, the network was divided into 15 clusters and 45 samples were taken. Langelier, Ryznar, Puckorius, Larson-Skold (LS) and Aggressive indices were determined and compared to the marble test. The mean parameters included were pH (7.8 ± 0.1), electrical conductivity (1,083.9 ± 108.7 μS/cm), total dissolved solids (595.7 ± 54.7 mg/L), Cl (203.5 ± 18.7 mg/L), SO₄(174.7 ± 16.0 mg/L), alkalinity (134.5 ± 9.7 mg/L), total hardness (156.5 ± 9.3 mg/L), HCO₃(137.4 ± 13.0 mg/L) and calcium hardness (71.8 ± 4.3 mg/L). According to the Ryznar, Puckorius and Aggressive Indices, all samples were stable; based on the Langelier Index, 73% of samples were slightly corrosive and the rest were scale forming; according to the LS index, all samples were corrosive. Marble test results showed tested water of all 15 clusters tended to scale formation. Water in Bandar Abbas is slightly scale forming. The most appropriate indices for the network conditions are the Aggressive, Puckorius and Ryznar indices that were consistent with the marble test.

Practical scaling law for photoelectron angular distributions

International Nuclear Information System (INIS)

Guo Dongsheng; Zhang Jingtao; Xu Zhizhan; Li Xiaofeng; Fu Panming; Freeman, R.R.

2003-01-01

A practical scaling law that predicts photoelectron angular distributions (PADs) is derived using angular distribution formulas which explicitly contain spontaneous emission. The scaling law is used to analyze recent PAD measurements in above-threshold ionization, and to predict results of future experiments. Our theoretical and numerical studies show that, in the non-relativistic regime and long-wavelength approximation, the shapes of PADs are determined by only three dimensionless numbers: (1) u p ≡U p /(ℎ/2π)ω, the ponderomotive number (ponderomotive energy in units of laser photon energy); (2) ε b ≡E b /(ℎ/2π)ω, the binding number (atomic binding energy in units of the laser photon energy); (3) j, the absorbed-photon number. The scaling law is shown to be useful in predictions of results from strong-field Kapitza-Dirac effect measurements; specifically, the application of this scaling law to recently reported Kapitza-Dirac diffraction is discussed. Possible experimental tests to verify the scaling law are suggested

Large Scale Self-Organizing Information Distribution System

National Research Council Canada - National Science Library

Low, Steven

2005-01-01

This project investigates issues in "large-scale" networks. Here "large-scale" refers to networks with large number of high capacity nodes and transmission links, and shared by a large number of users...

A Web-based Distributed Voluntary Computing Platform for Large Scale Hydrological Computations

Science.gov (United States)

Demir, I.; Agliamzanov, R.

2014-12-01

Distributed volunteer computing can enable researchers and scientist to form large parallel computing environments to utilize the computing power of the millions of computers on the Internet, and use them towards running large scale environmental simulations and models to serve the common good of local communities and the world. Recent developments in web technologies and standards allow client-side scripting languages to run at speeds close to native application, and utilize the power of Graphics Processing Units (GPU). Using a client-side scripting language like JavaScript, we have developed an open distributed computing framework that makes it easy for researchers to write their own hydrologic models, and run them on volunteer computers. Users will easily enable their websites for visitors to volunteer sharing their computer resources to contribute running advanced hydrological models and simulations. Using a web-based system allows users to start volunteering their computational resources within seconds without installing any software. The framework distributes the model simulation to thousands of nodes in small spatial and computational sizes. A relational database system is utilized for managing data connections and queue management for the distributed computing nodes. In this paper, we present a web-based distributed volunteer computing platform to enable large scale hydrological simulations and model runs in an open and integrated environment.

Scaling strength distributions in quasi-brittle materials from micro-to macro-scales: A computational approach to modeling Nature-inspired structural ceramics

International Nuclear Information System (INIS)

Genet, Martin; Couegnat, Guillaume; Tomsia, Antoni P.; Ritchie, Robert O.

2014-01-01

This paper presents an approach to predict the strength distribution of quasi-brittle materials across multiple length-scales, with emphasis on Nature-inspired ceramic structures. It permits the computation of the failure probability of any structure under any mechanical load, solely based on considerations of the microstructure and its failure properties by naturally incorporating the statistical and size-dependent aspects of failure. We overcome the intrinsic limitations of single periodic unit-based approaches by computing the successive failures of the material components and associated stress redistributions on arbitrary numbers of periodic units. For large size samples, the microscopic cells are replaced by a homogenized continuum with equivalent stochastic and damaged constitutive behavior. After establishing the predictive capabilities of the method, and illustrating its potential relevance to several engineering problems, we employ it in the study of the shape and scaling of strength distributions across differing length-scales for a particular quasi-brittle system. We find that the strength distributions display a Weibull form for samples of size approaching the periodic unit; however, these distributions become closer to normal with further increase in sample size before finally reverting to a Weibull form for macroscopic sized samples. In terms of scaling, we find that the weakest link scaling applies only to microscopic, and not macroscopic scale, samples. These findings are discussed in relation to failure patterns computed at different size-scales. (authors)

The ATLAS distributed analysis system

International Nuclear Information System (INIS)

Legger, F

2014-01-01

In the LHC operations era, analysis of the multi-petabyte ATLAS data sample by globally distributed physicists is a challenging task. To attain the required scale the ATLAS Computing Model was designed around the concept of Grid computing, realized in the Worldwide LHC Computing Grid (WLCG), the largest distributed computational resource existing in the sciences. The ATLAS experiment currently stores over 140 PB of data and runs about 140,000 concurrent jobs continuously at WLCG sites. During the first run of the LHC, the ATLAS Distributed Analysis (DA) service has operated stably and scaled as planned. More than 1600 users submitted jobs in 2012, with 2 million or more analysis jobs per week, peaking at about a million jobs per day. The system dynamically distributes popular data to expedite processing and maximally utilize resources. The reliability of the DA service is high and steadily improving; Grid sites are continually validated against a set of standard tests, and a dedicated team of expert shifters provides user support and communicates user problems to the sites. Both the user support techniques and the direct feedback of users have been effective in improving the success rate and user experience when utilizing the distributed computing environment. In this contribution a description of the main components, activities and achievements of ATLAS distributed analysis is given. Several future improvements being undertaken will be described.

The ATLAS distributed analysis system

Science.gov (United States)

Legger, F.; Atlas Collaboration

2014-06-01

In the LHC operations era, analysis of the multi-petabyte ATLAS data sample by globally distributed physicists is a challenging task. To attain the required scale the ATLAS Computing Model was designed around the concept of Grid computing, realized in the Worldwide LHC Computing Grid (WLCG), the largest distributed computational resource existing in the sciences. The ATLAS experiment currently stores over 140 PB of data and runs about 140,000 concurrent jobs continuously at WLCG sites. During the first run of the LHC, the ATLAS Distributed Analysis (DA) service has operated stably and scaled as planned. More than 1600 users submitted jobs in 2012, with 2 million or more analysis jobs per week, peaking at about a million jobs per day. The system dynamically distributes popular data to expedite processing and maximally utilize resources. The reliability of the DA service is high and steadily improving; Grid sites are continually validated against a set of standard tests, and a dedicated team of expert shifters provides user support and communicates user problems to the sites. Both the user support techniques and the direct feedback of users have been effective in improving the success rate and user experience when utilizing the distributed computing environment. In this contribution a description of the main components, activities and achievements of ATLAS distributed analysis is given. Several future improvements being undertaken will be described.

Implementation of Pilot Protection System for Large Scale Distribution System like The Future Renewable Electric Energy Distribution Management Project

Science.gov (United States)

Iigaya, Kiyohito

A robust, fast and accurate protection system based on pilot protection concept was developed previously and a few alterations in that algorithm were made to make it faster and more reliable and then was applied to smart distribution grids to verify the results for it. The new 10 sample window method was adapted into the pilot protection program and its performance for the test bed system operation was tabulated. Following that the system comparison between the hardware results for the same algorithm and the simulation results were compared. The development of the dual slope percentage differential method, its comparison with the 10 sample average window pilot protection system and the effects of CT saturation on the pilot protection system are also shown in this thesis. The implementation of the 10 sample average window pilot protection system is done to multiple distribution grids like Green Hub v4.3, IEEE 34, LSSS loop and modified LSSS loop. Case studies of these multi-terminal model are presented, and the results are also shown in this thesis. The result obtained shows that the new algorithm for the previously proposed protection system successfully identifies fault on the test bed and the results for both hardware and software simulations match and the response time is approximately less than quarter of a cycle which is fast as compared to the present commercial protection system and satisfies the FREEDM system requirement.

Using Citizen Science Observations to Model Species Distributions Over Space, Through Time, and Across Scales

Science.gov (United States)

Kelling, S.

2017-12-01

The goal of Biodiversity research is to identify, explain, and predict why a species' distribution and abundance vary through time, space, and with features of the environment. Measuring these patterns and predicting their responses to change are not exercises in curiosity. Today, they are essential tasks for understanding the profound effects that humans have on earth's natural systems, and for developing science-based environmental policies. To gain insight about species' distribution patterns requires studying natural systems at appropriate scales, yet studies of ecological processes continue to be compromised by inadequate attention to scale issues. How spatial and temporal patterns in nature change with scale often reflects fundamental laws of physics, chemistry, or biology, and we can identify such basic, governing laws only by comparing patterns over a wide range of scales. This presentation will provide several examples that integrate bird observations made by volunteers, with NASA Earth Imagery using Big Data analysis techniques to analyze the temporal patterns of bird occurrence across scales—from hemisphere-wide views of bird distributions to the impact of powerful city lights on bird migration.

Characteristic functions of scale mixtures of multivariate skew-normal distributions

KAUST Repository

Kim, Hyoung-Moon

2011-08-01

We obtain the characteristic function of scale mixtures of skew-normal distributions both in the univariate and multivariate cases. The derivation uses the simple stochastic relationship between skew-normal distributions and scale mixtures of skew-normal distributions. In particular, we describe the characteristic function of skew-normal, skew-t, and other related distributions. © 2011 Elsevier Inc.

Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system.

Science.gov (United States)

Sun, Huifang; Shi, Baoyou; Yang, Fan; Wang, Dongsheng

2017-05-01

Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R 2  > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe 3 O 4 ) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO 3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe 3 O 4 . The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe 6 (OH) 12 CO 3 content under higher sulfate concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel probabilistic and distributed algorithms for guidance, control, and nonlinear estimation of large-scale multi-agent systems

Science.gov (United States)

Bandyopadhyay, Saptarshi

Multi-agent systems are widely used for constructing a desired formation shape, exploring an area, surveillance, coverage, and other cooperative tasks. This dissertation introduces novel algorithms in the three main areas of shape formation, distributed estimation, and attitude control of large-scale multi-agent systems. In the first part of this dissertation, we address the problem of shape formation for thousands to millions of agents. Here, we present two novel algorithms for guiding a large-scale swarm of robotic systems into a desired formation shape in a distributed and scalable manner. These probabilistic swarm guidance algorithms adopt an Eulerian framework, where the physical space is partitioned into bins and the swarm's density distribution over each bin is controlled using tunable Markov chains. In the first algorithm - Probabilistic Swarm Guidance using Inhomogeneous Markov Chains (PSG-IMC) - each agent determines its bin transition probabilities using a time-inhomogeneous Markov chain that is constructed in real-time using feedback from the current swarm distribution. This PSG-IMC algorithm minimizes the expected cost of the transitions required to achieve and maintain the desired formation shape, even when agents are added to or removed from the swarm. The algorithm scales well with a large number of agents and complex formation shapes, and can also be adapted for area exploration applications. In the second algorithm - Probabilistic Swarm Guidance using Optimal Transport (PSG-OT) - each agent determines its bin transition probabilities by solving an optimal transport problem, which is recast as a linear program. In the presence of perfect feedback of the current swarm distribution, this algorithm minimizes the given cost function, guarantees faster convergence, reduces the number of transitions for achieving the desired formation, and is robust to disturbances or damages to the formation. We demonstrate the effectiveness of these two proposed swarm

Distributed Systems: The Hard Problems

CERN Multimedia

CERN. Geneva

2015-01-01

**Nicholas Bellerophon** works as a client services engineer at Basho Technologies, helping customers setup and run distributed systems at scale in the wild. He has also worked in massively multiplayer games, and recently completed a live scalable simulation engine. He is an avid TED-watcher with interests in many areas of the arts, science, and engineering, including of course high-energy physics.

Scaling function, spectral function and nucleon momentum distribution in nuclei

International Nuclear Information System (INIS)

Antonov, A.N.; Ivanov, M.V.; Caballero, J.A.; Barbaro, M.B.; Udias, J.M.; Moya de Guerra, E.; Donnelly, T.W.

2010-01-01

The aim of the study is to find a good simultaneous description of the spectral function and the momentum distribution in relation to the realistic scaling function obtained from inclusive electron-nuclei scattering experiments. We start with a modified Hartree-Fock spectral function in which the energy dependent part (δ-function) is replaced by the Gaussian distributions with hole state widths as free parameters. We calculate the scaling function and the nucleon momentum distribution on the basis of the spectral function constructed in this way, trying to find a good description of the experimental data. The obtained scaling function has a weak asymmetry and the momentum distribution has not got a high-momentum tail in the case when harmonic-oscillator single-particle wave functions are used. So, to improve the behavior of the momentum distribution we used the basis of natural orbitals (NO) in which short-range correlations are partly incorporated. The results for the scaling function show again a weak asymmetry, but in this case the momentum distribution has a high-momentum tail. As a next step we include final-state interactions (FSI) in the calculations to reproduce the experimentally observed asymmetry of the scaling function. (author)

Phylogenetic distribution of large-scale genome patchiness

Directory of Open Access Journals (Sweden)

Hackenberg Michael

2008-04-01

Full Text Available Abstract Background The phylogenetic distribution of large-scale genome structure (i.e. mosaic compositional patchiness has been explored mainly by analytical ultracentrifugation of bulk DNA. However, with the availability of large, good-quality chromosome sequences, and the recently developed computational methods to directly analyze patchiness on the genome sequence, an evolutionary comparative analysis can be carried out at the sequence level. Results The local variations in the scaling exponent of the Detrended Fluctuation Analysis are used here to analyze large-scale genome structure and directly uncover the characteristic scales present in genome sequences. Furthermore, through shuffling experiments of selected genome regions, computationally-identified, isochore-like regions were identified as the biological source for the uncovered large-scale genome structure. The phylogenetic distribution of short- and large-scale patchiness was determined in the best-sequenced genome assemblies from eleven eukaryotic genomes: mammals (Homo sapiens, Pan troglodytes, Mus musculus, Rattus norvegicus, and Canis familiaris, birds (Gallus gallus, fishes (Danio rerio, invertebrates (Drosophila melanogaster and Caenorhabditis elegans, plants (Arabidopsis thaliana and yeasts (Saccharomyces cerevisiae. We found large-scale patchiness of genome structure, associated with in silico determined, isochore-like regions, throughout this wide phylogenetic range. Conclusion Large-scale genome structure is detected by directly analyzing DNA sequences in a wide range of eukaryotic chromosome sequences, from human to yeast. In all these genomes, large-scale patchiness can be associated with the isochore-like regions, as directly detected in silico at the sequence level.

Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.

Science.gov (United States)

Wang, Wendong; Song, Shan; Zhang, Xiaoni; Mitchell Spear, J; Wang, Xiaochang; Wang, Wen; Ding, Zhenzhen; Qiao, Zixia

2014-07-01

Observations of aluminum containing sediments/scales formed within the distribution pipes have been reported for several decades. In this study, the effect of Ni(2+) on the formation and transformation processes of aluminum hydroxide sediment in a simulated drinking water distribution system were investigated using X-ray diffraction spectrum (XRD), Fourier transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and thermodynamic calculation methods. It was determined that the existence of Ni(2+) had notable effects on the formation of bayerite. In the system without Ni(2+) addition, there was no X-ray diffraction signal observed after 400 d of aging. The presence of Ni(2+), however, even when present in small amounts (Ni/Al=1:100) the formation of bayerite would occur in as little as 3d at pH 8.5. As the molar ratio of Ni/Al increase from 1:100 to 1:10, the amount of bayerite formed on the pipeline increased further; meanwhile, the specific area of the pipe scale decreased from 160 to 122 m(2)g(-1). In the system with Ni/Al molar ratio at 1:3, the diffraction spectrum strength of bayerite became weaker, and disappeared when Ni/Al molar ratios increased above 1:1. At these highs Ni/Al molar ratios, Ni5Al4O11⋅18H2O was determined to be the major component of the pipe scale. Further study indicated that the presence of Ni(2+) promoted the formation of bayerite and Ni5Al4O11⋅18H2O under basic conditions. At lower pH (6.5) however, the existence of Ni(2+) had little effect on the formation of bayerite and Ni5Al4O11⋅18H2O, rather the adsorption of amorphous Al(OH)3 for Ni(2+) promoted the formation of crystal Ni(OH)2. Copyright © 2013 Elsevier Ltd. All rights reserved.

VisIO: enabling interactive visualization of ultra-scale, time-series data via high-bandwidth distributed I/O systems

Energy Technology Data Exchange (ETDEWEB)

Mitchell, Christopher J [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Wang, Jun [UCF

2010-10-15

Petascale simulations compute at resolutions ranging into billions of cells and write terabytes of data for visualization and analysis. Interactive visuaUzation of this time series is a desired step before starting a new run. The I/O subsystem and associated network often are a significant impediment to interactive visualization of time-varying data; as they are not configured or provisioned to provide necessary I/O read rates. In this paper, we propose a new I/O library for visualization applications: VisIO. Visualization applications commonly use N-to-N reads within their parallel enabled readers which provides an incentive for a shared-nothing approach to I/O, similar to other data-intensive approaches such as Hadoop. However, unlike other data-intensive applications, visualization requires: (1) interactive performance for large data volumes, (2) compatibility with MPI and POSIX file system semantics for compatibility with existing infrastructure, and (3) use of existing file formats and their stipulated data partitioning rules. VisIO, provides a mechanism for using a non-POSIX distributed file system to provide linear scaling of 110 bandwidth. In addition, we introduce a novel scheduling algorithm that helps to co-locate visualization processes on nodes with the requested data. Testing using VisIO integrated into Para View was conducted using the Hadoop Distributed File System (HDFS) on TACC's Longhorn cluster. A representative dataset, VPIC, across 128 nodes showed a 64.4% read performance improvement compared to the provided Lustre installation. Also tested, was a dataset representing a global ocean salinity simulation that showed a 51.4% improvement in read performance over Lustre when using our VisIO system. VisIO, provides powerful high-performance I/O services to visualization applications, allowing for interactive performance with ultra-scale, time-series data.

Characteristic functions of scale mixtures of multivariate skew-normal distributions

KAUST Repository

Kim, Hyoung-Moon; Genton, Marc G.

2011-01-01

We obtain the characteristic function of scale mixtures of skew-normal distributions both in the univariate and multivariate cases. The derivation uses the simple stochastic relationship between skew-normal distributions and scale mixtures of skew

Allometric Scaling and Central Source Systems

International Nuclear Information System (INIS)

Dreyer, Olaf

2001-01-01

Allometric scaling relations abound in nature. Examples include the power law relating the metabolic rate of animals and plants to their masses and the power law describing the dependence of the size of the drainage basin of a river on the total amount of water contained in that river. The exponent is of the form D/D+1 , where D is the dimension of the system. We show that this scaling exponent is simply a consequence of the source distribution of the systems considered and requires no further assumptions. To demonstrate the wide range of validity of the result we present a simple experiment that shows the predicted behavior in one dimension

DISCO - A concept of a system for integrated data base management in distributed data processing systems

International Nuclear Information System (INIS)

Holler, E.

1980-01-01

The development in data processing technology favors the trend towards distributed data processing systems: The large-scale integration of semiconductor devices has lead to very efficient (approx. 10 6 operations per second) and relatively cheap low end computers being offered today, that allow to install distributed data processing systems with a total capacity coming near to that of large-scale data processing plants at a tolerable investment expenditure. The technologies of communication and data banks, each by itself, have reached a state of development justifying their routine application. This is made evident by the present efforts for standardization in both areas. The integration of both technologies in the development of systems for integrated distributed data bank management, however, is new territory for engineering. (orig.) [de

Empirical evidence for multi-scaled controls on wildfire size distributions in California

Science.gov (United States)

Povak, N.; Hessburg, P. F., Sr.; Salter, R. B.

2014-12-01

Ecological theory asserts that regional wildfire size distributions are examples of self-organized critical (SOC) systems. Controls on SOC event-size distributions by virtue are purely endogenous to the system and include the (1) frequency and pattern of ignitions, (2) distribution and size of prior fires, and (3) lagged successional patterns after fires. However, recent work has shown that the largest wildfires often result from extreme climatic events, and that patterns of vegetation and topography may help constrain local fire spread, calling into question the SOC model's simplicity. Using an atlas of >12,000 California wildfires (1950-2012) and maximum likelihood estimation (MLE), we fit four different power-law models and broken-stick regressions to fire-size distributions across 16 Bailey's ecoregions. Comparisons among empirical fire size distributions across ecoregions indicated that most ecoregion's fire-size distributions were significantly different, suggesting that broad-scale top-down controls differed among ecoregions. One-parameter power-law models consistently fit a middle range of fire sizes (~100 to 10000 ha) across most ecoregions, but did not fit to larger and smaller fire sizes. We fit the same four power-law models to patch size distributions of aspect, slope, and curvature topographies and found that the power-law models fit to a similar middle range of topography patch sizes. These results suggested that empirical evidence may exist for topographic controls on fire sizes. To test this, we used neutral landscape modeling techniques to determine if observed fire edges corresponded with aspect breaks more often than expected by random. We found significant differences between the empirical and neutral models for some ecoregions, particularly within the middle range of fire sizes. Our results, combined with other recent work, suggest that controls on ecoregional fire size distributions are multi-scaled and likely are not purely SOC. California

Discrete scale-free distributions and associated limit theorems

International Nuclear Information System (INIS)

Hopcraft, K I; Jakeman, E; Matthews, J O

2004-01-01

Consideration is given to the convergence properties of sums of identical, independently distributed random variables drawn from a class of discrete distributions with power-law tails, which are relevant to scale-free networks. Different limiting distributions, and rates of convergence to these limits, are identified and depend on the index of the tail. For indices ≥2, the topology evolves to a random Poisson network, but the rate of convergence can be extraordinarily slow and unlikely to be yet evident for the current size of the WWW for example. It is shown that treating discrete scale-free behaviour with continuum or mean-field approximations can lead to incorrect results. (letter to the editor)

Scale and shape mixtures of multivariate skew-normal distributions

KAUST Repository

Arellano-Valle, Reinaldo B.; Ferreira, Clé cio S.; Genton, Marc G.

2018-01-01

We introduce a broad and flexible class of multivariate distributions obtained by both scale and shape mixtures of multivariate skew-normal distributions. We present the probabilistic properties of this family of distributions in detail and lay down

Scale-invariant matter distribution in the universe

International Nuclear Information System (INIS)

Balian, R.; Schaeffer, R.

1989-01-01

We calculate the galaxy counts or the matter content within a randomly placed cell, under the sole hypothesis of scale-invariance of the many-body correlations functions. The various forms taken by the probability for finding N objects in a given volume are obtained as a function of its size. At smallscales ( -1 Mpc), this probability decreases exponentially with N. At larger scales (0.5h -1 Mpc to 10h -1 Mpc) it behaves as a power-law with an upper and possibly a lower exponential cut-off, reminiscent of the current parametrizations of the galaxy and cluster luminosity functions. We show that the large scale void probability, whose logarithm is seen to be a power-law, is a scale-free extrapolation of its small scale behaviour. As long as the correlation functions are power-laws, this void distribution is not compatible with the linear theory, whatever large scale is considered. We relate this large-scale behaviour of the void probability to the power-law observed at the faint end of the luminosity functions. A scaling law is found, the galaxy and cluster distributions being expressed by the same universal function. We show that the counts in cells are approximately gaussian, only at very large scales, above 50h -1 Mpc, provived the density fluctuations are less than 10% of the mean. In the intermediate range of 10h -1 to 50h -1 Mpc, considerable deviations from gaussian statistics are predicted. Counts in cells are seen to provide a cleaner statistical tool than the mass or luminosity functions and are as easy to obtain either from theoretical information on correlation functions or from observations

Distributed photovoltaic generation in Brazil: An economic viability analysis of small-scale photovoltaic systems in the residential and commercial sectors

International Nuclear Information System (INIS)

Holdermann, Claudius; Kissel, Johannes; Beigel, Jürgen

2014-01-01

This paper examines the economic viability of small-scale, grid-connected photovoltaics in the Brazilian residential and commercial sectors after the introduction of the net metering regulation in April 2012. This study uses the discounted cash flow method to calculate the specific investment costs that are necessary for photovoltaic systems to be economically viable for each of the 63 distribution networks in Brazil. We compare these values to the system costs that are estimated in the comprehensive study on photovoltaics that was developed by the Brazilian Association of Electric and Electronic Industries (ABINEE). In our calculation, we utilize the current electricity tariffs, including fees and taxes, which we obtained through telephone interviews and publicly available information. We obtained a second important parameter by simulating PV-systems with the program PV ⁎ Sol at the distribution company headquarters' locations. In our base case scenario that reflects the current situation, in none of the distribution networks photovoltaics is economically viable in either the commercial or residential sectors. We improved the environment for grid-connected photovoltaics in our scenarios by assuming both lower PV-system costs and a lower discount rate to determine the effect on photovoltaics viability. - Highlights: • We calculate the economic viability of photovoltaics in the residential and commercial sectors in Brazil. • The PV ⁎ Sol simulations are carried out at the headquarter locations for the 63 distribution companies. • Currently in none of the distribution networks, photovoltaics is economically viable in either the commercial or residential sectors. • We analyze how the variation of the specific investment costs and of the discount rate affects the economic viability

Competition and Cooperation of Distributed Generation and Power System

Science.gov (United States)

Miyake, Masatoshi; Nanahara, Toshiya

Advances in distributed generation technologies together with the deregulation of an electric power industry can lead to a massive introduction of distributed generation. Since most of distributed generation will be interconnected to a power system, coordination and competition between distributed generators and large-scale power sources would be a vital issue in realizing a more desirable energy system in the future. This paper analyzes competitions between electric utilities and cogenerators from the viewpoints of economic and energy efficiency based on the simulation results on an energy system including a cogeneration system. First, we examine best response correspondence of an electric utility and a cogenerator with a noncooperative game approach: we obtain a Nash equilibrium point. Secondly, we examine the optimum strategy that attains the highest social surplus and the highest energy efficiency through global optimization.

Electric distribution systems and embedded generation capacity

International Nuclear Information System (INIS)

Calderaro, V.; Galdi, V.; Piccolo, A.; Siano, P.

2006-01-01

The main policy issues of European States are sustainable energy supply promotion and liberalization of energy markets, which introduced market competition in electricity production and created support mechanisms to encourage renewable electricity production and consumption. As a result of liberalization, any generator, including small-scale and renewable energy based units, can sell electricity on the free market. In order to meet future sustainability targets, connection of a higher number of Distributed Generation (DG) units to the electrical power system is expected, requiring changes in the design and operation of distribution electricity systems, as well as changes in electricity network regulation. In order to assist distribution system operators in planning and managing DG connections and in maximizing DG penetration and renewable sources exploitation, this paper proposed a reconfiguration methodology based on a Genetic Algorithm (GA), that was tested on a 70-bus system with DG units. The simulation results confirmed that the methodology represents a suitable tool for distribution system operators when dealing with DG capacity expansion and power loss issues, providing information regarding the potential penetration network-wide and allowing maximum exploitation of renewable generation. 35 refs., 4 tabs., 6 figs

SPATIAL DISTRIBUTION OF POVERTY AT DIFFERENT SCALES

Directory of Open Access Journals (Sweden)

Gandhi PAWITAN

2010-01-01

Full Text Available Poverty mapping is usually developed from some sources of data, such as from census and survey data. In some practical application, the poverty was measured usually by household income or expenditure of daily basic consumption. Using different scales and zoning on a particular set of spatial data may leads to problems in interpreting the results. In practice, organizations publish statistics and maps at a particular area level. Minot and Baulch (2005a discussed some consequences of using aggregated level data in poverty mapping, which may affect the validity of the output. The key point of this paper is to compare spatial distribution of the poverty at two different scale, which is the province and district level. How the spatial distribution of the poverty at province level can be use to infer the distribution at the district level. The geographical weighted regression will be applied, and the poverty data of Vietnam will be used as an illustration.

Needs, opportunities, and options for large scale systems research

Energy Technology Data Exchange (ETDEWEB)

Thompson, G.L.

1984-10-01

The Office of Energy Research was recently asked to perform a study of Large Scale Systems in order to facilitate the development of a true large systems theory. It was decided to ask experts in the fields of electrical engineering, chemical engineering and manufacturing/operations research for their ideas concerning large scale systems research. The author was asked to distribute a questionnaire among these experts to find out their opinions concerning recent accomplishments and future research directions in large scale systems research. He was also requested to convene a conference which included three experts in each area as panel members to discuss the general area of large scale systems research. The conference was held on March 26--27, 1984 in Pittsburgh with nine panel members, and 15 other attendees. The present report is a summary of the ideas presented and the recommendations proposed by the attendees.

Prototyping a large-scale distributed system for the Great Observatories era - NASA Astrophysics Data System (ADS)

Science.gov (United States)

Shames, Peter

1990-01-01

The NASA Astrophysics Data System (ADS) is a distributed information system intended to support research in the Great Observatories era, to simplify access to data, and to enable simultaneous analyses of multispectral data sets. Here, the user agent and interface, its functions, and system components are examined, and the system architecture and infrastructure is addressed. The present status of the system and related future activities are examined.

Effectiveness of Devices to Monitor Biofouling and Metals Deposition on Plumbing Materials Exposed to a Full-Scale Drinking Water Distribution System

OpenAIRE

Ginige, Maneesha P.; Garbin, Scott; Wylie, Jason; Krishna, K. C. Bal

2017-01-01

A Modified Robbins Device (MRD) was installed in a full-scale water distribution system to investigate biofouling and metal depositions on concrete, high-density polyethylene (HDPE) and stainless steel surfaces. Bulk water monitoring and a KIWA monitor (with glass media) were used to offline monitor biofilm development on pipe wall surfaces. Results indicated that adenosine triphosphate (ATP) and metal concentrations on coupons increased with time. However, bacterial diversities decreased. Th...

Watchdog - a workflow management system for the distributed analysis of large-scale experimental data.

Science.gov (United States)

Kluge, Michael; Friedel, Caroline C

2018-03-13

The development of high-throughput experimental technologies, such as next-generation sequencing, have led to new challenges for handling, analyzing and integrating the resulting large and diverse datasets. Bioinformatical analysis of these data commonly requires a number of mutually dependent steps applied to numerous samples for multiple conditions and replicates. To support these analyses, a number of workflow management systems (WMSs) have been developed to allow automated execution of corresponding analysis workflows. Major advantages of WMSs are the easy reproducibility of results as well as the reusability of workflows or their components. In this article, we present Watchdog, a WMS for the automated analysis of large-scale experimental data. Main features include straightforward processing of replicate data, support for distributed computer systems, customizable error detection and manual intervention into workflow execution. Watchdog is implemented in Java and thus platform-independent and allows easy sharing of workflows and corresponding program modules. It provides a graphical user interface (GUI) for workflow construction using pre-defined modules as well as a helper script for creating new module definitions. Execution of workflows is possible using either the GUI or a command-line interface and a web-interface is provided for monitoring the execution status and intervening in case of errors. To illustrate its potentials on a real-life example, a comprehensive workflow and modules for the analysis of RNA-seq experiments were implemented and are provided with the software in addition to simple test examples. Watchdog is a powerful and flexible WMS for the analysis of large-scale high-throughput experiments. We believe it will greatly benefit both users with and without programming skills who want to develop and apply bioinformatical workflows with reasonable overhead. The software, example workflows and a comprehensive documentation are freely

Computational optimization of catalyst distributions at the nano-scale

International Nuclear Information System (INIS)

Ström, Henrik

2017-01-01

Highlights: • Macroscopic data sampled from a DSMC simulation contain statistical scatter. • Simulated annealing is evaluated as an optimization algorithm with DSMC. • Proposed method is more robust than a gradient search method. • Objective function uses the mass transfer rate instead of the reaction rate. • Combined algorithm is more efficient than a macroscopic overlay method. - Abstract: Catalysis is a key phenomenon in a great number of energy processes, including feedstock conversion, tar cracking, emission abatement and optimizations of energy use. Within heterogeneous, catalytic nano-scale systems, the chemical reactions typically proceed at very high rates at a gas–solid interface. However, the statistical uncertainties characteristic of molecular processes pose efficiency problems for computational optimizations of such nano-scale systems. The present work investigates the performance of a Direct Simulation Monte Carlo (DSMC) code with a stochastic optimization heuristic for evaluations of an optimal catalyst distribution. The DSMC code treats molecular motion with homogeneous and heterogeneous chemical reactions in wall-bounded systems and algorithms have been devised that allow optimization of the distribution of a catalytically active material within a three-dimensional duct (e.g. a pore). The objective function is the outlet concentration of computational molecules that have interacted with the catalytically active surface, and the optimization method used is simulated annealing. The application of a stochastic optimization heuristic is shown to be more efficient within the present DSMC framework than using a macroscopic overlay method. Furthermore, it is shown that the performance of the developed method is superior to that of a gradient search method for the current class of problems. Finally, the advantages and disadvantages of different types of objective functions are discussed.

Scaling Techniques for Massive Scale-Free Graphs in Distributed (External) Memory

KAUST Repository

Pearce, Roger

2013-05-01

We present techniques to process large scale-free graphs in distributed memory. Our aim is to scale to trillions of edges, and our research is targeted at leadership class supercomputers and clusters with local non-volatile memory, e.g., NAND Flash. We apply an edge list partitioning technique, designed to accommodate high-degree vertices (hubs) that create scaling challenges when processing scale-free graphs. In addition to partitioning hubs, we use ghost vertices to represent the hubs to reduce communication hotspots. We present a scaling study with three important graph algorithms: Breadth-First Search (BFS), K-Core decomposition, and Triangle Counting. We also demonstrate scalability on BG/P Intrepid by comparing to best known Graph500 results. We show results on two clusters with local NVRAM storage that are capable of traversing trillion-edge scale-free graphs. By leveraging node-local NAND Flash, our approach can process thirty-two times larger datasets with only a 39% performance degradation in Traversed Edges Per Second (TEPS). © 2013 IEEE.

Family of probability distributions derived from maximal entropy principle with scale invariant restrictions.

Science.gov (United States)

Sonnino, Giorgio; Steinbrecher, György; Cardinali, Alessandro; Sonnino, Alberto; Tlidi, Mustapha

2013-01-01

Using statistical thermodynamics, we derive a general expression of the stationary probability distribution for thermodynamic systems driven out of equilibrium by several thermodynamic forces. The local equilibrium is defined by imposing the minimum entropy production and the maximum entropy principle under the scale invariance restrictions. The obtained probability distribution presents a singularity that has immediate physical interpretation in terms of the intermittency models. The derived reference probability distribution function is interpreted as time and ensemble average of the real physical one. A generic family of stochastic processes describing noise-driven intermittency, where the stationary density distribution coincides exactly with the one resulted from entropy maximization, is presented.

The Integration of Renewable Energy Sources into Electric Power Distribution Systems, Vol. II Utility Case Assessments

Energy Technology Data Exchange (ETDEWEB)

Zaininger, H.W.

1994-01-01

Electric utility distribution system impacts associated with the integration of renewable energy sources such as photovoltaics (PV) and wind turbines (WT) are considered in this project. The impacts are expected to vary from site to site according to the following characteristics: the local solar insolation and/or wind characteristics, renewable energy source penetration level, whether battery or other energy storage systems are applied, and local utility distribution design standards and planning practices. Small, distributed renewable energy sources are connected to the utility distribution system like other, similar kW- and MW-scale equipment and loads. Residential applications are expected to be connected to single-phase 120/240-V secondaries. Larger kW-scale applications may be connected to three+phase secondaries, and larger hundred-kW and y-scale applications, such as MW-scale windfarms, or PV plants, may be connected to electric utility primary systems via customer-owned primary and secondary collection systems. In any case, the installation of small, distributed renewable energy sources is expected to have a significant impact on local utility distribution primary and secondary system economics. Small, distributed renewable energy sources installed on utility distribution systems will also produce nonsite-specific utility generation system benefits such as energy and capacity displacement benefits, in addition to the local site-specific distribution system benefits. Although generation system benefits are not site-specific, they are utility-specific, and they vary significantly among utilities in different regions. In addition, transmission system benefits, environmental benefits and other benefits may apply. These benefits also vary significantly among utilities and regions. Seven utility case studies considering PV, WT, and battery storage were conducted to identify a range of potential renewable energy source distribution system applications. The

Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

Science.gov (United States)

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

Directory of Open Access Journals (Sweden)

Luis Carlos Pinto de Macedo-Soares

Full Text Available Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

Science.gov (United States)

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Performance of water distribution systems in a pilot cooling tower

International Nuclear Information System (INIS)

Tognotti, L.; Giacomelli, A.; Zanelli, S.; Bellagamba, B.; Lotti, G.; Mattachini, F.

1990-01-01

An experimental study has been carried out on the water distribution system of a Pilot cooling tower of 160 m 3 /hr The performances of different industrial water distributors have been evaluated by changing the operative conditions of the pilot tower. In particular, the efficiency and the uniformity of the water distribution have been investigated and compared with the results obtained in a small-scale loop, in which the single nozzles were tested. Measurements in both systems, pilot tower and small scale loop, included the geometric characteristics of the jet umbrella by ensemble photography, the wetted zone by measuring the specific flowrate, the drop-size distribution and liquid concentration by high-speed photography. The results show that correlations exist between the nozzle behaviour in single and pilot tower configuration. The uniformity of water distribution in the pilot tower is strongly related to the nozzle installation pattern and to the operative conditions. Coalescence plays an important role on the drop size distribution in the pilot-tower. Comments upon the influence of these parameters on tower behaviour are also included

Spatial distribution of enzyme driven reactions at micro-scales

Science.gov (United States)

Kandeler, Ellen; Boeddinghaus, Runa; Nassal, Dinah; Preusser, Sebastian; Marhan, Sven; Poll, Christian

2017-04-01

Studies of microbial biogeography can often provide key insights into the physiologies, environmental tolerances, and ecological strategies of soil microorganisms that dominate in natural environments. In comparison with aquatic systems, soils are particularly heterogeneous. Soil heterogeneity results from the interaction of a hierarchical series of interrelated variables that fluctuate at many different spatial and temporal scales. Whereas spatial dependence of chemical and physical soil properties is well known at scales ranging from decimetres to several hundred metres, the spatial structure of soil enzymes is less clear. Previous work has primarily focused on spatial heterogeneity at a single analytical scale using the distribution of individual cells, specific types of organisms or collective parameters such as bacterial abundance or total microbial biomass. There are fewer studies that have considered variations in community function and soil enzyme activities. This presentation will give an overview about recent studies focusing on spatial pattern of different soil enzymes in the terrestrial environment. Whereas zymography allows the visualization of enzyme pattern in the close vicinity of roots, micro-sampling strategies followed by MUF analyses clarify micro-scale pattern of enzymes associated to specific microhabitats (micro-aggregates, organo-mineral complexes, subsoil compartments).

Scaling of charged particle multiplicity distributions in relativistic nuclear collisions

International Nuclear Information System (INIS)

Ahamd, N.; Hushnud; Azmi, M.D.; Zafar, M.; Irfan, M.; Khan, M.M.; Tufail, A.

2011-01-01

Validity of KNO scaling in hadron-hadron and hadron-nucleus collisions has been tested by several workers. Multiplicity distributions for p-emulsion interactions are found to be consistent with the KNO scaling hypothesis for pp collisions. The applicability of the scaling law was extended to FNAL energies by earlier workers. Slattery has shown that KNO scaling hypothesis is in fine agreement with the data for pp interactions over a wide range of incident energies. An attempt, is, therefore, made to examine the scaling hypothesis using multiplicity distributions of particles produced in 3.7A GeV/c 16 O-, 4.5A GeV/c and 14.5A GeV/c 28 Si - nucleus interactions

Large-scale geographic variation in distribution and abundance of Australian deep-water kelp forests.

Directory of Open Access Journals (Sweden)

Ezequiel M Marzinelli

Full Text Available Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV facility of Australia's Integrated Marine Observing System (IMOS to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10-100 m to 100-1,000 km and depths (15-60 m across several regions ca 2-6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40-50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves.

Smart Distribution Systems

Directory of Open Access Journals (Sweden)

Yazhou Jiang

2016-04-01

Full Text Available The increasing importance of system reliability and resilience is changing the way distribution systems are planned and operated. To achieve a distribution system self-healing against power outages, emerging technologies and devices, such as remote-controlled switches (RCSs and smart meters, are being deployed. The higher level of automation is transforming traditional distribution systems into the smart distribution systems (SDSs of the future. The availability of data and remote control capability in SDSs provides distribution operators with an opportunity to optimize system operation and control. In this paper, the development of SDSs and resulting benefits of enhanced system capabilities are discussed. A comprehensive survey is conducted on the state-of-the-art applications of RCSs and smart meters in SDSs. Specifically, a new method, called Temporal Causal Diagram (TCD, is used to incorporate outage notifications from smart meters for enhanced outage management. To fully utilize the fast operation of RCSs, the spanning tree search algorithm is used to develop service restoration strategies. Optimal placement of RCSs and the resulting enhancement of system reliability are discussed. Distribution system resilience with respect to extreme events is presented. Test cases are used to demonstrate the benefit of SDSs. Active management of distributed generators (DGs is introduced. Future research in a smart distribution environment is proposed.

A Distributed Approach to System-Level Prognostics

Science.gov (United States)

Daigle, Matthew J.; Bregon, Anibal; Roychoudhury, Indranil

2012-01-01

Prognostics, which deals with predicting remaining useful life of components, subsystems, and systems, is a key technology for systems health management that leads to improved safety and reliability with reduced costs. The prognostics problem is often approached from a component-centric view. However, in most cases, it is not specifically component lifetimes that are important, but, rather, the lifetimes of the systems in which these components reside. The system-level prognostics problem can be quite difficult due to the increased scale and scope of the prognostics problem and the relative Jack of scalability and efficiency of typical prognostics approaches. In order to address these is ues, we develop a distributed solution to the system-level prognostics problem, based on the concept of structural model decomposition. The system model is decomposed into independent submodels. Independent local prognostics subproblems are then formed based on these local submodels, resul ting in a scalable, efficient, and flexible distributed approach to the system-level prognostics problem. We provide a formulation of the system-level prognostics problem and demonstrate the approach on a four-wheeled rover simulation testbed. The results show that the system-level prognostics problem can be accurately and efficiently solved in a distributed fashion.

Operational Analysis of Distribution Systems Featuring Large-scale Variable RES: Contributions of Energy Storage Systems and Switchable Capacitor Banks

OpenAIRE

Mário Pascoal Santos Pereira

2017-01-01

In the last decade, the level of variable renewable energy sources (RESs) integrated in distribution network systems have been continuously growing. This adds more uncertainty to these systems, which also face many traditional sources of uncertainty, and those pertaining to other emerging technologies such as demand response and electric vehicles. As a result, distribution system operators are finding it increasingly difficult to maintain an optimal operation of such network systems. These ch...

Scale dependence and small-x behaviour of polarized parton distributions

International Nuclear Information System (INIS)

Ball, R.D.; Forte, S.; Ridolfi, G.

1995-01-01

We discuss perturbative evolution of the polarized structure function g 1 in the (x, Q 2 ) plane, with special regard to the small-x region. We determine g 1 in terms of polarized quark and gluon distributions using coefficient functions to order α s . At small x g 1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution. ((orig.))

Scale dependence and small x behaviour of polarized parton distributions

CERN Document Server

Ball, R D; Ridolfi, G; Forte, S; Ridolfi, G

1995-01-01

We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to order alpha_s. At small x g_1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution.

Scaling precipitation input to spatially distributed hydrological models by measured snow distribution

Directory of Open Access Journals (Sweden)

Christian Vögeli

2016-12-01

Full Text Available Accurate knowledge on snow distribution in alpine terrain is crucial for various applicationssuch as flood risk assessment, avalanche warning or managing water supply and hydro-power.To simulate the seasonal snow cover development in alpine terrain, the spatially distributed,physics-based model Alpine3D is suitable. The model is typically driven by spatial interpolationsof observations from automatic weather stations (AWS, leading to errors in the spatial distributionof atmospheric forcing. With recent advances in remote sensing techniques, maps of snowdepth can be acquired with high spatial resolution and accuracy. In this work, maps of the snowdepth distribution, calculated from summer and winter digital surface models based on AirborneDigital Sensors (ADS, are used to scale precipitation input data, with the aim to improve theaccuracy of simulation of the spatial distribution of snow with Alpine3D. A simple method toscale and redistribute precipitation is presented and the performance is analysed. The scalingmethod is only applied if it is snowing. For rainfall the precipitation is distributed by interpolation,with a simple air temperature threshold used for the determination of the precipitation phase.It was found that the accuracy of spatial snow distribution could be improved significantly forthe simulated domain. The standard deviation of absolute snow depth error is reduced up toa factor 3.4 to less than 20 cm. The mean absolute error in snow distribution was reducedwhen using representative input sources for the simulation domain. For inter-annual scaling, themodel performance could also be improved, even when using a remote sensing dataset from adifferent winter. In conclusion, using remote sensing data to process precipitation input, complexprocesses such as preferential snow deposition and snow relocation due to wind or avalanches,can be substituted and modelling performance of spatial snow distribution is improved.

Power-law citation distributions are not scale-free.

Science.gov (United States)

Golosovsky, Michael

2017-09-01

We analyze time evolution of statistical distributions of citations to scientific papers published in the same year. While these distributions seem to follow the power-law dependence we find that they are nonstationary and the exponent of the power-law fit decreases with time and does not come to saturation. We attribute the nonstationarity of citation distributions to different longevity of the low-cited and highly cited papers. By measuring citation trajectories of papers we found that citation careers of the low-cited papers come to saturation after 10-15 years while those of the highly cited papers continue to increase indefinitely: The papers that exceed some citation threshold become runaways. Thus, we show that although citation distribution can look as a power-law dependence, it is not scale free and there is a hidden dynamic scale associated with the onset of runaways. We compare our measurements to our recently developed model of citation dynamics based on copying-redirection-triadic closure and find explanations to our empirical observations.

Adaptive intelligent power systems: Active distribution networks

International Nuclear Information System (INIS)

McDonald, Jim

2008-01-01

Electricity networks are extensive and well established. They form a key part of the infrastructure that supports industrialised society. These networks are moving from a period of stability to a time of potentially major transition, driven by a need for old equipment to be replaced, by government policy commitments to cleaner and renewable sources of electricity generation, and by change in the power industry. This paper looks at moves towards active distribution networks. The novel transmission and distribution systems of the future will challenge today's system designs. They will cope with variable voltages and frequencies, and will offer more flexible, sustainable options. Intelligent power networks will need innovation in several key areas of information technology. Active control of flexible, large-scale electrical power systems is required. Protection and control systems will have to react to faults and unusual transient behaviour and ensure recovery after such events. Real-time network simulation and performance analysis will be needed to provide decision support for system operators, and the inputs to energy and distribution management systems. Advanced sensors and measurement will be used to achieve higher degrees of network automation and better system control, while pervasive communications will allow networks to be reconfigured by intelligent systems

A Comparison of Producer Gas, Biochar, and Activated Carbon from Two Distributed Scale Thermochemical Conversion Systems Used to Process Forest Biomass

Directory of Open Access Journals (Sweden)

Nathaniel Anderson

2013-01-01

Full Text Available Thermochemical biomass conversion systems have the potential to produce heat, power, fuels and other products from forest biomass at distributed scales that meet the needs of some forest industry facilities. However, many of these systems have not been deployed in this sector and the products they produce from forest biomass have not been adequately described or characterized with regards to chemical properties, possible uses, and markets. This paper characterizes the producer gas, biochar, and activated carbon of a 700 kg h−1 prototype gasification system and a 225 kg h−1 pyrolysis system used to process coniferous sawmill and forest residues. Producer gas from sawmill residues processed with the gasifier had higher energy content than gas from forest residues, with averages of 12.4 MJ m−3 and 9.8 MJ m−3, respectively. Gases from the pyrolysis system averaged 1.3 MJ m−3 for mill residues and 2.5 MJ m−3 for forest residues. Biochars produced have similar particle size distributions and bulk density, but vary in pH and carbon content. Biochars from both systems were successfully activated using steam activation, with resulting BET surface area in the range of commercial activated carbon. Results are discussed in the context of co-locating these systems with forest industry operations.

Influence of different initial distributions on robust cooperation in scale-free networks: A comparative study

International Nuclear Information System (INIS)

Chen Xiaojie; Fu Feng; Wang Long

2008-01-01

We study the evolutionary Prisoner's dilemma game on scale-free networks, focusing on the influence of different initial distributions for cooperators and defectors on the evolution of cooperation. To address this issue, we consider three types of initial distributions for defectors: uniform distribution at random, occupying the most connected nodes, and occupying the lowest-degree nodes, respectively. It is shown that initial configurations for defectors can crucially influence the cooperation level and the evolution speed of cooperation. Interestingly, the situation where defectors initially occupy the lowest-degree vertices can exhibit the most robust cooperation, compared with two other distributions. That is, the cooperation level is least affected by the initial percentage of defectors. Moreover, in this situation, the whole system evolves fastest to the prevalent cooperation. Besides, we obtain the critical values of initial frequency of defectors above which the extinction of cooperators occurs for the respective initial distributions. Our results might be helpful in explaining the maintenance of high cooperation in scale-free networks

Climate Controls AM Fungal Distributions from Global to Local Scales

Science.gov (United States)

Kivlin, S. N.; Hawkes, C.; Muscarella, R.; Treseder, K. K.; Kazenel, M.; Lynn, J.; Rudgers, J.

2016-12-01

Arbuscular mycorrhizal (AM) fungi have key functions in terrestrial biogeochemical processes; thus, determining the relative importance of climate, edaphic factors, and plant community composition on their geographic distributions can improve predictions of their sensitivity to global change. Local adaptation by AM fungi to plant hosts, soil nutrients, and climate suggests that all of these factors may control fungal geographic distributions, but their relative importance is unknown. We created species distribution models for 142 AM fungal taxa at the global scale with data from GenBank. We compared climate variables (BioClim and soil moisture), edaphic variables (phosphorus, carbon, pH, and clay content), and plant variables using model selection on models with (1) all variables, (2) climatic variables only (including soil moisture) and (3) resource-related variables only (all other soil parameters and NPP) using the MaxEnt algorithm evaluated with ENMEval. We also evaluated whether drivers of AM fungal distributions were phylogenetically conserved. To test whether global correlates of AM fungal distributions were reflected at local scales, we then surveyed AM fungi in nine plant hosts along three elevation gradients in the Upper Gunnison Basin, Colorado, USA. At the global scale, the distributions of 55% of AM fungal taxa were affected by both climate and soil resources, whereas 16% were only affected by climate and 29% were only affected by soil resources. Even for AM fungi that were affected by both climate and resources, the effects of climatic variables nearly always outweighed those of resources. Soil moisture and isothermality were the main climatic and NPP and soil carbon the main resource related factors influencing AM fungal distributions. Distributions of closely related AM fungal taxa were similarly affected by climate, but not by resources. Local scale surveys of AM fungi across elevations confirmed that climate was a key driver of AM fungal

Ceph, a distributed storage system for scientific computing

CERN Multimedia

CERN. Geneva

2013-01-01

Ceph is a distributed storage system designed to providing high performance and reliability at scales of up to thousands of storage nodes. The system is based on a distributed object storage layer call RADOS that provides durability, availability, efficient data distribution, and rich object semantics. This storage can be consumed directly via an object-based interface, or via file, block, or REST-based object services that are built on top of it. Clusters are composed of commodity components to provide a reliable storage service serving multiple use-cases. This seminar will cover the basic architecture of Ceph, with a focus on how each service can be consumed in a research and infrastructure environment. About the speaker Sage Weil, Founder and current CTO of Inktank Inc, is the creator of the Ceph project. He originally designed it as part of his PhD research in Storage Systems at the University of California, Santa Cruz. Since graduating, he has continued to refine the system with the goal of providi...

Top-k aggregation queries in large-scale distributed systems

OpenAIRE

Michel, Sebastian

2007-01-01

Distributed top-k query processing has recently become an essential functionality in a large number of emerging application classes like Internet traffic monitoring and Peer-to-Peer Web search. This work addresses efficient algorithms for distributed top-k queries in wide-area networks where the index lists for the attribute values (or text terms) of a query are distributed across a number of data peers. More precisely, in this thesis, we make the following distributions: We present the fa...

Does the stellar distribution flare? A comparison of stellar scale heights with LAB H I data

Energy Technology Data Exchange (ETDEWEB)

Kalberla, P. M. W.; Kerp, J.; Dedes, L. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn (Germany); Haud, U., E-mail: pkalberla@astro.uni-bonn.de [Tartu Observatory, 61602 Tõravere (Estonia)

2014-10-10

The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

Voltage stability issues in a distribution grid with large scale PV plant

Energy Technology Data Exchange (ETDEWEB)

Perez, Alvaro Ruiz; Marinopoulos, Antonios; Reza, Muhamad; Srivastava, Kailash [ABB AB, Vaesteraas (Sweden). Corporate Research Center; Hertem, Dirk van [Katholieke Univ. Leuven, Heverlee (Belgium). ESAT-ELECTA

2011-07-01

Solar photovoltaics (PV) has become a competitive renewable energy source. The production of solar PV cells and panels has increased significantly, while the cost is reduced due to economics of scale and technological achievements in the field. At the same time, the increase in efficiency of PV power systems and high energy prices are expected to lead PV systems to grid parity in the coming decade. This is expected to boost even more the large scale implementation of PV power plants (utility scale PV) and therefore the impact of such large scale PV plants to power system needs to be studies. This paper investigates the voltage stability issues arising from the connection of a large PV power plant to the power grid. For this purpose, a 15 MW PV power plant was implemented into a distribution grid, modeled and simulated using DIgSILENT Power Factory. Two scenarios were developed: in the first scenario, active power injected into the grid by the PV power plants was varied and the resulted U-Q curve was analyzed. In the second scenario, the impact of connecting PV power plants to different points in the grid - resulting in different strength of the connection - was investigated. (orig.)

Security and VO management capabilities in a large-scale Grid operating system

OpenAIRE

Aziz, Benjamin; Sporea, Ioana

2014-01-01

This paper presents a number of security and VO management capabilities in a large-scale distributed Grid operating system. The capabilities formed the basis of the design and implementation of a number of security and VO management services in the system. The main aim of the paper is to provide some idea of the various functionality cases that need to be considered when designing similar large-scale systems in the future.

Distributed Electrical Energy Systems: Needs, Concepts, Approaches and Vision

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yingchen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Jun [University of Denver; Gao, Wenzhong [University of Denver; Zheng, Xinhu [University of Minnesota; Yang, Liuqing [Colorado State University; Hao, Jun [University of Denver; Dai, Xiaoxiao [University of Denver

2017-09-01

Intelligent distributed electrical energy systems (IDEES) are featured by vast system components, diversifled component types, and difficulties in operation and management, which results in that the traditional centralized power system management approach no longer flts the operation. Thus, it is believed that the blockchain technology is one of the important feasible technical paths for building future large-scale distributed electrical energy systems. An IDEES is inherently with both social and technical characteristics, as a result, a distributed electrical energy system needs to be divided into multiple layers, and at each layer, a blockchain is utilized to model and manage its logic and physical functionalities. The blockchains at difierent layers coordinate with each other and achieve successful operation of the IDEES. Speciflcally, the multi-layer blockchains, named 'blockchain group', consist of distributed data access and service blockchain, intelligent property management blockchain, power system analysis blockchain, intelligent contract operation blockchain, and intelligent electricity trading blockchain. It is expected that the blockchain group can be self-organized into a complex, autonomous and distributed IDEES. In this complex system, frequent and in-depth interactions and computing will derive intelligence, and it is expected that such intelligence can bring stable, reliable and efficient electrical energy production, transmission and consumption.

Distributed processor systems

International Nuclear Information System (INIS)

Zacharov, B.

1976-01-01

In recent years, there has been a growing tendency in high-energy physics and in other fields to solve computational problems by distributing tasks among the resources of inter-coupled processing devices and associated system elements. This trend has gained further momentum more recently with the increased availability of low-cost processors and with the development of the means of data distribution. In two lectures, the broad question of distributed computing systems is examined and the historical development of such systems reviewed. An attempt is made to examine the reasons for the existence of these systems and to discern the main trends for the future. The components of distributed systems are discussed in some detail and particular emphasis is placed on the importance of standards and conventions in certain key system components. The ideas and principles of distributed systems are discussed in general terms, but these are illustrated by a number of concrete examples drawn from the context of the high-energy physics environment. (Auth.)

The brain as a distributed intelligent processing system: an EEG study.

Science.gov (United States)

da Rocha, Armando Freitas; Rocha, Fábio Theoto; Massad, Eduardo

2011-03-15

Various neuroimaging studies, both structural and functional, have provided support for the proposal that a distributed brain network is likely to be the neural basis of intelligence. The theory of Distributed Intelligent Processing Systems (DIPS), first developed in the field of Artificial Intelligence, was proposed to adequately model distributed neural intelligent processing. In addition, the neural efficiency hypothesis suggests that individuals with higher intelligence display more focused cortical activation during cognitive performance, resulting in lower total brain activation when compared with individuals who have lower intelligence. This may be understood as a property of the DIPS. In our study, a new EEG brain mapping technique, based on the neural efficiency hypothesis and the notion of the brain as a Distributed Intelligence Processing System, was used to investigate the correlations between IQ evaluated with WAIS (Wechsler Adult Intelligence Scale) and WISC (Wechsler Intelligence Scale for Children), and the brain activity associated with visual and verbal processing, in order to test the validity of a distributed neural basis for intelligence. The present results support these claims and the neural efficiency hypothesis.

Performance Monitoring of Residential Hot Water Distribution Systems

Energy Technology Data Exchange (ETDEWEB)

Liao, Anna; Lanzisera, Steven; Lutz, Jim; Fitting, Christian; Kloss, Margarita; Stiles, Christopher

2014-08-11

Current water distribution systems are designed such that users need to run the water for some time to achieve the desired temperature, wasting energy and water in the process. We developed a wireless sensor network for large-scale, long time-series monitoring of residential water end use. Our system consists of flow meters connected to wireless motes transmitting data to a central manager mote, which in turn posts data to our server via the internet. This project also demonstrates a reliable and flexible data collection system that could be configured for various other forms of end use metering in buildings. The purpose of this study was to determine water and energy use and waste in hot water distribution systems in California residences. We installed meters at every end use point and the water heater in 20 homes and collected 1s flow and temperature data over an 8 month period. For a typical shower and dishwasher events, approximately half the energy is wasted. This relatively low efficiency highlights the importance of further examining the energy and water waste in hot water distribution systems.

Memory intensive functional architecture for distributed computer control systems

International Nuclear Information System (INIS)

Dimmler, D.G.

1983-10-01

A memory-intensive functional architectue for distributed data-acquisition, monitoring, and control systems with large numbers of nodes has been conceptually developed and applied in several large-scale and some smaller systems. This discussion concentrates on: (1) the basic architecture; (2) recent expansions of the architecture which now become feasible in view of the rapidly developing component technologies in microprocessors and functional large-scale integration circuits; and (3) implementation of some key hardware and software structures and one system implementation which is a system for performing control and data acquisition of a neutron spectrometer at the Brookhaven High Flux Beam Reactor. The spectrometer is equipped with a large-area position-sensitive neutron detector

Distributed hierarchical radiation monitoring system

International Nuclear Information System (INIS)

Barak, D.

1985-01-01

A solution to the problem of monitoring the radiation levels in and around a nuclear facility is presented in this paper. This is a private case of a large scale general purpose data acqisition system with high reliability, availability and short maintenance time. The physical layout of the detectors in the plant, and the strict control demands dictated a distributed and hierarchical system. The system is comprised of three levels, each level contains modules. Level one contains the Control modules which collects data from groups of detectors and executes emergency local control tasks. In level two are the Group controllers which concentrate data from the Control modules, and enable local display and communication. The system computer is in level three, enabling the plant operator to receive information from the detectors and execute control tasks. The described system was built and is operating successfully for about two years. (author)

Assessment of distributed solar power systems: Issues and impacts

Science.gov (United States)

Moyle, R. A.; Chernoff, H.; Schweizer, T. C.; Patton, J. B.

1982-11-01

The installation of distributed solar-power systems presents electric utilities with a host of questions. Some of the technical and economic impacts of these systems are discussed. Among the technical interconnect issues are isolated operation, power quality, line safety, and metering options. Economic issues include user purchase criteria, structures and installation costs, marketing and product distribution costs, and interconnect costs. An interactive computer program that allows easy calculation of allowable system prices and allowable generation-equipment prices was developed as part of this project. It is concluded that the technical problems raised by distributed solar systems are surmountable, but their resolution may be costly. The stringent purchase criteria likely to be imposed by many potential system users and the economies of large-scale systems make small systems (less than 10 to 20 kW) less attractive than larger systems. Utilities that consider life-cycle costs in making investment decisions and third-party investors who have tax and financial advantages are likely to place the highest value on solar-power systems.

Thallium-rich rust scales in drinkable water distribution systems: A case study from northern Tuscany, Italy.

Science.gov (United States)

Biagioni, Cristian; D'Orazio, Massimo; Lepore, Giovanni O; d'Acapito, Francesco; Vezzoni, Simone

2017-06-01

Following the detection of a severe thallium contamination of the drinkable water from the public distribution system of Valdicastello Carducci-Pietrasanta (northern Tuscany, Italy), and the identification of the source of contamination in the Molini di Sant'Anna spring (average Tl content≈15μgL -1 ), the replacement of the contaminated water with a virtually Tl-free one (Tlwater. This suggested that the pipeline interior had become a secondary source of Tl contamination, promoting its mineralogical and geochemical study. Rust scales samples taken from several pipeline segments, as well as leaching products obtained from these samples, were investigated through scanning electron microscopy, X-ray fluorescence chemical analyses, inductively coupled plasma - mass spectrometry, X-ray diffraction, and X-ray absorption spectroscopy. Thallium-rich rust scales (up to 5.3wt% Tl) have been found only in pipeline samples taken downstream the water treatment plant, whereas the sample taken upstream contains much less Tl (~90μgg -1 ). The Tl-rich nature of such scales is related to the occurrence of nano- and micro-spherules of Tl 2 O 3 and less abundant nanocrystalline μm-sized encrustations of TlCl. Leaching experiments on Tl-rich rust scales indicate that a fraction of the available Tl is easily dissolved in tap water; X-ray absorption spectroscopy suggests that monovalent thallium occurs in water equilibrated with the rust scales, probably related to the dissolution of TlCl encrustations. Therefore, Tl dissolved as Tl + only in the water from the Molini di Sant'Anna spring was partially removed through oxidative precipitation of Tl 2 O 3 and precipitation of TlCl. This highlights the critical role played by the addition of chlorine-based oxidants in water treatment plants that could favour the deposition of Tl-rich coatings within the pipelines, giving rise to unexpected secondary sources of contamination. Copyright © 2017 Elsevier B.V. All rights reserved.

Microtomography and pore-scale modeling of two-phase Fluid Distribution

Energy Technology Data Exchange (ETDEWEB)

Silin, D.; Tomutsa, L.; Benson, S.; Patzek, T.

2010-10-19

Synchrotron-based X-ray microtomography (micro CT) at the Advanced Light Source (ALS) line 8.3.2 at the Lawrence Berkeley National Laboratory produces three-dimensional micron-scale-resolution digital images of the pore space of the reservoir rock along with the spacial distribution of the fluids. Pore-scale visualization of carbon dioxide flooding experiments performed at a reservoir pressure demonstrates that the injected gas fills some pores and pore clusters, and entirely bypasses the others. Using 3D digital images of the pore space as input data, the method of maximal inscribed spheres (MIS) predicts two-phase fluid distribution in capillary equilibrium. Verification against the tomography images shows a good agreement between the computed fluid distribution in the pores and the experimental data. The model-predicted capillary pressure curves and tomography-based porosimetry distributions compared favorably with the mercury injection data. Thus, micro CT in combination with modeling based on the MIS is a viable approach to study the pore-scale mechanisms of CO{sub 2} injection into an aquifer, as well as more general multi-phase flows.

Development of distributed measurement and control systems for application in electrical energy systems

Directory of Open Access Journals (Sweden)

Gajić Tomislav

2013-01-01

Full Text Available In this paper LPC1766 microcontroller based network capable application processor (NCAP system, is described. This system is intended to be used in modern distributed control and monitoring systems for application in power plants and industry, as well as in modern electricity distribution networks. In order to do that it is necessary to analyze different aspects of the system, like signal processing part or communication requirements. The chosen microcontroller has enough resources to satisfy requirements of an transducer interface module (TIM. Beside the realization of NCAp and TIM controllers it is necessary to develop the necessary measurement modules, in order to realize measurement-control systems. The developed layout could be connected to actuators to the local area network (LAN, as well. If the local LAN is connected to the internet it is possible to monitor and configure measurement modules form the remote site. Having in mind the growing complexity in control systems, it has been a real challenge to detect a diagnose problems in today's large scale distributed systems. Implementation of the proposed module could potentially reduce the time necessary to extract necessary information from the abundant quantity of information that are usually provided by the complex distributed systems.

New power distribution challenges at the local scale

International Nuclear Information System (INIS)

Delage, Marion; Cadoux, Florent; Petit, Marc

2016-01-01

Distribution grids are facing the connection of both more and more variable distributed generation sources and new loads such as electric vehicles. Then distribution grid operators evolve to distribution system operators (DSOs) with new flexibilities (power control of distributed energy sources) to complete their traditional planning and operation tools. In the future, additional distributed resources could be used, such as demand response and storage. DSOs are becoming actors of a global electrical system where power balancing must be ensured at the European level with local constraints (congestion and voltage), and with power flows from transmission to distribution grids but also inside the distribution grid or from distribution to transmission. Sensors and data availability are key issues to enable these transformations. This paper defines some general concerns and present European issues with illustrations from the French electrical system. (authors)

Mapping the distribution of the denitrifier community at large scales (Invited)

Science.gov (United States)

Philippot, L.; Bru, D.; Ramette, A.; Dequiedt, S.; Ranjard, L.; Jolivet, C.; Arrouays, D.

2010-12-01

Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. Here we combined molecular approaches and geostatistical modeling to explore spatial patterns of the denitrifying community at large scales. The distribution of denitrifrying community was investigated over 107 sites in Burgundy, a 31 500 km2 region of France, using a 16 X 16 km sampling grid. At each sampling site, the abundances of denitrifiers and 42 soil physico-chemical properties were measured. The relative contributions of land use, spatial distance, climatic conditions, time and soil physico-chemical properties to the denitrifier spatial distribution were analyzed by canonical variation partitioning. Our results indicate that 43% to 85% of the spatial variation in community abundances could be explained by the measured environmental parameters, with soil chemical properties (mostly pH) being the main driver. We found spatial autocorrelation up to 740 km and used geostatistical modelling to generate predictive maps of the distribution of denitrifiers at the landscape scale. Studying the distribution of the denitrifiers at large scale can help closing the artificial gap between the investigation of microbial processes and microbial community ecology, therefore facilitating our understanding of the relationships between the ecology of denitrifiers and N-fluxes by denitrification.

Measurement-Based Spatial Correlation and Capacity of Indoor Distributed MIMO System

Directory of Open Access Journals (Sweden)

Yan Zhang

2013-01-01

Full Text Available Distributed MIMO (D-MIMO system is one of the candidates for future wireless access networks. In this study, the spatial correlation and capacity in indoor D-MIMO system are presented. All results are from the actual channel measurements in typical indoor scenarios, including office and corridor. Based on measured data, spatial correlation coefficients between distributed transmitting antennas are analyzed. Although the literature about D-MIMO system assumes the small scale fading between distributed antennas is independent, we find that spatial correlation may still exist in specific propagation scenario. This correlation can also degrade the performance of D-MIMO system. To mitigate the impact of spatial correlation, one efficient method is to use transmitting antenna selection technique.

Large-scale computing techniques for complex system simulations

CERN Document Server

Dubitzky, Werner; Schott, Bernard

2012-01-01

Complex systems modeling and simulation approaches are being adopted in a growing number of sectors, including finance, economics, biology, astronomy, and many more. Technologies ranging from distributed computing to specialized hardware are explored and developed to address the computational requirements arising in complex systems simulations. The aim of this book is to present a representative overview of contemporary large-scale computing technologies in the context of complex systems simulations applications. The intention is to identify new research directions in this field and

Electric distribution systems

CERN Document Server

Sallam, A A

2010-01-01

"Electricity distribution is the penultimate stage in the delivery of electricity to end users. The only book that deals with the key topics of interest to distribution system engineers, Electric Distribution Systems presents a comprehensive treatment of the subject with an emphasis on both the practical and academic points of view. Reviewing traditional and cutting-edge topics, the text is useful to practicing engineers working with utility companies and industry, undergraduate graduate and students, and faculty members who wish to increase their skills in distribution system automation and monitoring."--

Modeling the spatial distribution of crop cultivated areas at a large regional scale combining system dynamics and a modified Dyna-CLUE: A case from Iran

Energy Technology Data Exchange (ETDEWEB)

Mesgari, I.; Saeed Jabalameli, M.

2017-07-01

Agricultural land use pattern is affected by many factors at different scales and effects that are separated by time and space. This will lead to simulation models that optimize or project the cropping pattern changes and incorporate complexities in terms of details and dynamics. Combining System Dynamics (SD) and a modified Conversion of Land Use and its Effects (CLUE) modelling framework, this paper suggests a new dynamic approach for assessing the demand of different crops at country-level and for predicting the spatial distribution of cultivated areas at provincial scale. As example, a case study is presented for Iran, where we have simulated a scenario of future cropping pattern changes during 2015–2040.The results indicated a change in the spatial distribution of cultivated areas during the next years. An increase in the proportion of rice is expected in northern Iran, whereas the proportion of wheat is increasing in the mountainous western areas. Wheat and barley crops are expected to become dominant within the cropping system throughout the country regions.

Scaling in the distribution of intertrade durations of Chinese stocks

Science.gov (United States)

Jiang, Zhi-Qiang; Chen, Wei; Zhou, Wei-Xing

2008-10-01

The distribution of intertrade durations, defined as the waiting times between two consecutive transactions, is investigated based upon the limit order book data of 23 liquid Chinese stocks listed on the Shenzhen Stock Exchange in the whole year 2003. A scaling pattern is observed in the distributions of intertrade durations, where the empirical density functions of the normalized intertrade durations of all 23 stocks collapse onto a single curve. The scaling pattern is also observed in the intertrade duration distributions for filled and partially filled trades and in the conditional distributions. The ensemble distributions for all stocks are modeled by the Weibull and the Tsallis q-exponential distributions. Maximum likelihood estimation shows that the Weibull distribution outperforms the q-exponential for not-too-large intertrade durations which account for more than 98.5% of the data. Alternatively, nonlinear least-squares estimation selects the q-exponential as a better model, in which the optimization is conducted on the distance between empirical and theoretical values of the logarithmic probability densities. The distribution of intertrade durations is Weibull followed by a power-law tail with an asymptotic tail exponent close to 3.

Data-driven process decomposition and robust online distributed modelling for large-scale processes

Science.gov (United States)

Shu, Zhang; Lijuan, Li; Lijuan, Yao; Shipin, Yang; Tao, Zou

2018-02-01

With the increasing attention of networked control, system decomposition and distributed models show significant importance in the implementation of model-based control strategy. In this paper, a data-driven system decomposition and online distributed subsystem modelling algorithm was proposed for large-scale chemical processes. The key controlled variables are first partitioned by affinity propagation clustering algorithm into several clusters. Each cluster can be regarded as a subsystem. Then the inputs of each subsystem are selected by offline canonical correlation analysis between all process variables and its controlled variables. Process decomposition is then realised after the screening of input and output variables. When the system decomposition is finished, the online subsystem modelling can be carried out by recursively block-wise renewing the samples. The proposed algorithm was applied in the Tennessee Eastman process and the validity was verified.

Dynamics of bacterial communities before and after distribution in a full-scale drinking water network.

Science.gov (United States)

El-Chakhtoura, Joline; Prest, Emmanuelle; Saikaly, Pascal; van Loosdrecht, Mark; Hammes, Frederik; Vrouwenvelder, Hans

2015-05-01

Understanding the biological stability of drinking water distribution systems is imperative in the framework of process control and risk management. The objective of this research was to examine the dynamics of the bacterial community during drinking water distribution at high temporal resolution. Water samples (156 in total) were collected over short time-scales (minutes/hours/days) from the outlet of a treatment plant and a location in its corresponding distribution network. The drinking water is treated by biofiltration and disinfectant residuals are absent during distribution. The community was analyzed by 16S rRNA gene pyrosequencing and flow cytometry as well as conventional, culture-based methods. Despite a random dramatic event (detected with pyrosequencing and flow cytometry but not with plate counts), the bacterial community profile at the two locations did not vary significantly over time. A diverse core microbiome was shared between the two locations (58-65% of the taxa and 86-91% of the sequences) and found to be dependent on the treatment strategy. The bacterial community structure changed during distribution, with greater richness detected in the network and phyla such as Acidobacteria and Gemmatimonadetes becoming abundant. The rare taxa displayed the highest dynamicity, causing the major change during water distribution. This change did not have hygienic implications and is contingent on the sensitivity of the applied methods. The concept of biological stability therefore needs to be revised. Biostability is generally desired in drinking water guidelines but may be difficult to achieve in large-scale complex distribution systems that are inherently dynamic. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dynamics of bacterial communities before and after distribution in a full-scale drinking water network

KAUST Repository

El Chakhtoura, Joline

2015-05-01

Understanding the biological stability of drinking water distribution systems is imperative in the framework of process control and risk management. The objective of this research was to examine the dynamics of the bacterial community during drinking water distribution at high temporal resolution. Water samples (156 in total) were collected over short time-scales (minutes/hours/days) from the outlet of a treatment plant and a location in its corresponding distribution network. The drinking water is treated by biofiltration and disinfectant residuals are absent during distribution. The community was analyzed by 16S rRNA gene pyrosequencing and flow cytometry as well as conventional, culture-based methods. Despite a random dramatic event (detected with pyrosequencing and flow cytometry but not with plate counts), the bacterial community profile at the two locations did not vary significantly over time. A diverse core microbiome was shared between the two locations (58-65% of the taxa and 86-91% of the sequences) and found to be dependent on the treatment strategy. The bacterial community structure changed during distribution, with greater richness detected in the network and phyla such as Acidobacteria and Gemmatimonadetes becoming abundant. The rare taxa displayed the highest dynamicity, causing the major change during water distribution. This change did not have hygienic implications and is contingent on the sensitivity of the applied methods. The concept of biological stability therefore needs to be revised. Biostability is generally desired in drinking water guidelines but may be difficult to achieve in large-scale complex distribution systems that are inherently dynamic.

Design of distributed PID-type dynamic matrix controller for fractional-order systems

Science.gov (United States)

Wang, Dawei; Zhang, Ridong

2018-01-01

With the continuous requirements for product quality and safety operation in industrial production, it is difficult to describe the complex large-scale processes with integer-order differential equations. However, the fractional differential equations may precisely represent the intrinsic characteristics of such systems. In this paper, a distributed PID-type dynamic matrix control method based on fractional-order systems is proposed. First, the high-order approximate model of integer order is obtained by utilising the Oustaloup method. Then, the step response model vectors of the plant is obtained on the basis of the high-order model, and the online optimisation for multivariable processes is transformed into the optimisation of each small-scale subsystem that is regarded as a sub-plant controlled in the distributed framework. Furthermore, the PID operator is introduced into the performance index of each subsystem and the fractional-order PID-type dynamic matrix controller is designed based on Nash optimisation strategy. The information exchange among the subsystems is realised through the distributed control structure so as to complete the optimisation task of the whole large-scale system. Finally, the control performance of the designed controller in this paper is verified by an example.

Multi-scale Clustering of Points Synthetically Considering Lines and Polygons Distribution

Directory of Open Access Journals (Sweden)

YU Li

2015-10-01

Full Text Available Considering the complexity and discontinuity of spatial data distribution, a clustering algorithm of points was proposed. To accurately identify and express the spatial correlation among points,lines and polygons, a Voronoi diagram that is generated by all spatial features is introduced. According to the distribution characteristics of point's position, an area threshold used to control clustering granularity was calculated. Meanwhile, judging scale convergence by constant area threshold, the algorithm classifies spatial features based on multi-scale, with an O(n log n running time.Results indicate that spatial scale converges self-adaptively according with distribution of points.Without the custom parameters, the algorithm capable to discover arbitrary shape clusters which be bound by lines and polygons, and is robust for outliers.

Distributed Data Management and Distributed File Systems

CERN Document Server

Girone, Maria

2015-01-01

The LHC program has been successful in part due to the globally distributed computing resources used for collecting, serving, processing, and analyzing the large LHC datasets. The introduction of distributed computing early in the LHC program spawned the development of new technologies and techniques to synchronize information and data between physically separated computing centers. Two of the most challenges services are the distributed file systems and the distributed data management systems. In this paper I will discuss how we have evolved from local site services to more globally independent services in the areas of distributed file systems and data management and how these capabilities may continue to evolve into the future. I will address the design choices, the motivations, and the future evolution of the computing systems used for High Energy Physics.

Scale effect challenges in urban hydrology highlighted with a distributed hydrological model

Science.gov (United States)

Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel; Bompard, Philippe; Ten Veldhuis, Marie-Claire

2018-01-01

Hydrological models are extensively used in urban water management, development and evaluation of future scenarios and research activities. There is a growing interest in the development of fully distributed and grid-based models. However, some complex questions related to scale effects are not yet fully understood and still remain open issues in urban hydrology. In this paper we propose a two-step investigation framework to illustrate the extent of scale effects in urban hydrology. First, fractal tools are used to highlight the scale dependence observed within distributed data input into urban hydrological models. Then an intensive multi-scale modelling work is carried out to understand scale effects on hydrological model performance. Investigations are conducted using a fully distributed and physically based model, Multi-Hydro, developed at Ecole des Ponts ParisTech. The model is implemented at 17 spatial resolutions ranging from 100 to 5 m. Results clearly exhibit scale effect challenges in urban hydrology modelling. The applicability of fractal concepts highlights the scale dependence observed within distributed data. Patterns of geophysical data change when the size of the observation pixel changes. The multi-scale modelling investigation confirms scale effects on hydrological model performance. Results are analysed over three ranges of scales identified in the fractal analysis and confirmed through modelling. This work also discusses some remaining issues in urban hydrology modelling related to the availability of high-quality data at high resolutions, and model numerical instabilities as well as the computation time requirements. The main findings of this paper enable a replacement of traditional methods of model calibration by innovative methods of model resolution alteration based on the spatial data variability and scaling of flows in urban hydrology.

Block scale interpretation on the spatial distribution of the fracture system in the study sites

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Su; Bae, Dae Seok; Kim, Chun Soo; Koh, Yong Kweon; Kim, Geon Young [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-05-01

The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures in rock mass. This study aims to characterize the spatial distribution characteristics of regional lineaments and background fracture system in eastern and western-type granite rock mass. The spatial distribution characteristics of the fracture system around 500m depth has been estimated based on the homogeneous discontinuity domain except for the highly fractured upper zone. 6 refs., 16 figs., 7 tabs. (Author)

The brain as a distributed intelligent processing system: an EEG study.

Directory of Open Access Journals (Sweden)

Armando Freitas da Rocha

Full Text Available BACKGROUND: Various neuroimaging studies, both structural and functional, have provided support for the proposal that a distributed brain network is likely to be the neural basis of intelligence. The theory of Distributed Intelligent Processing Systems (DIPS, first developed in the field of Artificial Intelligence, was proposed to adequately model distributed neural intelligent processing. In addition, the neural efficiency hypothesis suggests that individuals with higher intelligence display more focused cortical activation during cognitive performance, resulting in lower total brain activation when compared with individuals who have lower intelligence. This may be understood as a property of the DIPS. METHODOLOGY AND PRINCIPAL FINDINGS: In our study, a new EEG brain mapping technique, based on the neural efficiency hypothesis and the notion of the brain as a Distributed Intelligence Processing System, was used to investigate the correlations between IQ evaluated with WAIS (Wechsler Adult Intelligence Scale and WISC (Wechsler Intelligence Scale for Children, and the brain activity associated with visual and verbal processing, in order to test the validity of a distributed neural basis for intelligence. CONCLUSION: The present results support these claims and the neural efficiency hypothesis.

The Brain as a Distributed Intelligent Processing System: An EEG Study

Science.gov (United States)

da Rocha, Armando Freitas; Rocha, Fábio Theoto; Massad, Eduardo

2011-01-01

Background Various neuroimaging studies, both structural and functional, have provided support for the proposal that a distributed brain network is likely to be the neural basis of intelligence. The theory of Distributed Intelligent Processing Systems (DIPS), first developed in the field of Artificial Intelligence, was proposed to adequately model distributed neural intelligent processing. In addition, the neural efficiency hypothesis suggests that individuals with higher intelligence display more focused cortical activation during cognitive performance, resulting in lower total brain activation when compared with individuals who have lower intelligence. This may be understood as a property of the DIPS. Methodology and Principal Findings In our study, a new EEG brain mapping technique, based on the neural efficiency hypothesis and the notion of the brain as a Distributed Intelligence Processing System, was used to investigate the correlations between IQ evaluated with WAIS (Whechsler Adult Intelligence Scale) and WISC (Wechsler Intelligence Scale for Children), and the brain activity associated with visual and verbal processing, in order to test the validity of a distributed neural basis for intelligence. Conclusion The present results support these claims and the neural efficiency hypothesis. PMID:21423657

A uniform approach for programming distributed heterogeneous computing systems.

Science.gov (United States)

Grasso, Ivan; Pellegrini, Simone; Cosenza, Biagio; Fahringer, Thomas

2014-12-01

Large-scale compute clusters of heterogeneous nodes equipped with multi-core CPUs and GPUs are getting increasingly popular in the scientific community. However, such systems require a combination of different programming paradigms making application development very challenging. In this article we introduce libWater, a library-based extension of the OpenCL programming model that simplifies the development of heterogeneous distributed applications. libWater consists of a simple interface, which is a transparent abstraction of the underlying distributed architecture, offering advanced features such as inter-context and inter-node device synchronization. It provides a runtime system which tracks dependency information enforced by event synchronization to dynamically build a DAG of commands, on which we automatically apply two optimizations: collective communication pattern detection and device-host-device copy removal. We assess libWater's performance in three compute clusters available from the Vienna Scientific Cluster, the Barcelona Supercomputing Center and the University of Innsbruck, demonstrating improved performance and scaling with different test applications and configurations.

System-level power optimization for real-time distributed embedded systems

Science.gov (United States)

Luo, Jiong

Power optimization is one of the crucial design considerations for modern electronic systems. In this thesis, we present several system-level power optimization techniques for real-time distributed embedded systems, based on dynamic voltage scaling, dynamic power management, and management of peak power and variance of the power profile. Dynamic voltage scaling has been widely acknowledged as an important and powerful technique to trade off dynamic power consumption and delay. Efficient dynamic voltage scaling requires effective variable-voltage scheduling mechanisms that can adjust voltages and clock frequencies adaptively based on workloads and timing constraints. For this purpose, we propose static variable-voltage scheduling algorithms utilizing criticalpath driven timing analysis for the case when tasks are assumed to have uniform switching activities, as well as energy-gradient driven slack allocation for a more general scenario. The proposed techniques can achieve closeto-optimal power savings with very low computational complexity, without violating any real-time constraints. We also present algorithms for power-efficient joint scheduling of multi-rate periodic task graphs along with soft aperiodic tasks. The power issue is addressed through both dynamic voltage scaling and power management. Periodic task graphs are scheduled statically. Flexibility is introduced into the static schedule to allow the on-line scheduler to make local changes to PE schedules through resource reclaiming and slack stealing, without interfering with the validity of the global schedule. We provide a unified framework in which the response times of aperiodic tasks and power consumption are dynamically optimized simultaneously. Interconnection network fabrics point to a new generation of power-efficient and scalable interconnection architectures for distributed embedded systems. As the system bandwidth continues to increase, interconnection networks become power/energy limited as

SCALE system cross-section validation for criticality safety analysis

International Nuclear Information System (INIS)

Hathout, A.M.; Westfall, R.M.; Dodds, H.L. Jr.

1980-01-01

The purpose of this study is to test selected data from three cross-section libraries for use in the criticality safety analysis of UO 2 fuel rod lattices. The libraries, which are distributed with the SCALE system, are used to analyze potential criticality problems which could arise in the industrial fuel cycle for PWR and BWR reactors. Fuel lattice criticality problems could occur in pool storage, dry storage with accidental moderation, shearing and dissolution of irradiated elements, and in fuel transport and storage due to inadequate packing and shipping cask design. The data were tested by using the SCALE system to analyze 25 recently performed critical experiments

Scale and shape mixtures of multivariate skew-normal distributions

KAUST Repository

Arellano-Valle, Reinaldo B.

2018-02-26

We introduce a broad and flexible class of multivariate distributions obtained by both scale and shape mixtures of multivariate skew-normal distributions. We present the probabilistic properties of this family of distributions in detail and lay down the theoretical foundations for subsequent inference with this model. In particular, we study linear transformations, marginal distributions, selection representations, stochastic representations and hierarchical representations. We also describe an EM-type algorithm for maximum likelihood estimation of the parameters of the model and demonstrate its implementation on a wind dataset. Our family of multivariate distributions unifies and extends many existing models of the literature that can be seen as submodels of our proposal.

A Java based environment to control and monitor distributed processing systems

International Nuclear Information System (INIS)

Legrand, I.C.

1997-01-01

Distributed processing systems are considered to solve the challenging requirements of triggering and data acquisition systems for future HEP experiments. The aim of this work is to present a software environment to control and monitor large scale parallel processing systems based on a distributed client-server approach developed in Java. One server task may control several processing nodes, switching elements or controllers for different sub-systems. Servers are designed as multi-thread applications for efficient communications with other objects. Servers communicate between themselves by using Remote Method Invocation (RMI) in a peer-to-peer mechanism. This distributed server layer has to provide a dynamic and transparent access from any client to all the resources in the system. The graphical user interface programs, which are platform independent, may be transferred to any client via the http protocol. In this scheme the control and monitor tasks are distributed among servers and network controls the flow of information among servers and clients providing a flexible mechanism for monitoring and controlling large heterogenous distributed systems. (author)

Multi-Time Scale Control of Demand Flexibility in Smart Distribution Networks

DEFF Research Database (Denmark)

Bhattarai, Bishnu P.; Myers, Kurt S.; Bak-Jensen, Birgitte

2017-01-01

, and distribution system operator’s perspectives. A hierarchical control architecture (HCA) comprising scheduling, coordinative, and adaptive layers is then designed to realize their coordinative goal. This is realized by integrating multi-time scale controls that work from a day-ahead scheduling up to real-time...... adaptive control. The performance of the developed method is investigated with high EV penetration in a typical residential distribution grid. The simulation results demonstrate that HCA efficiently utilizes demand flexibility stemming from EVs to solve grid unbalancing and congestions with simultaneous...... maximization of economic benefits to the participating actors. This is ensured by enabling EV participation in day-ahead, balancing, and regulation markets. For the given network configuration and pricing structure, HCA ensures the EV owners to get paid up to five times the cost they were paying without...

Real-time Data Access Monitoring in Distributed, Multi-petabyte Systems

Energy Technology Data Exchange (ETDEWEB)

Azemoon, Tofigh; Becla, Jacek, a=Hanushevsky, Andrew; Turri, Massimiliano; /SLAC

2008-04-22

Petascale systems are in existence today and will become common in the next few years. Such systems are inevitably very complex, highly distributed and heterogeneous. Monitoring a petascale system in real-time and understanding its status at any given moment without impacting its performance is a highly intricate task. Common approaches and off-the-shelf tools are either unusable, do not scale, or severely impact the performance of the monitored servers. This paper describes unobtrusive monitoring software developed at Stanford Linear Accelerator Center (SLAC) for a highly distributed petascale production data set. The paper describes the employed solutions, the lessons learned, the problems still to be addressed, and explains how the system can be reused elsewhere.

ANTITRUST ISSUES IN THE LARGE-SCALE FOOD DISTRIBUTION SECTOR

Directory of Open Access Journals (Sweden)

Enrico Adriano Raffaelli

2014-12-01

Full Text Available In light of the slow modernization of the Italian large-scale food distribution sector, of the fragmentation at national level, of the significant roles of the cooperatives at local level and of the alliances between food retail chains, the ICA during the recent years has developed a strong interest in this sector.After having analyzed the peculiarities of the Italian large-scale food distribution sector, this article shows the recent approach taken by the ICA toward the main antitrust issues in this sector.In the analysis of such issues, mainly the contractual relations between the GDO retailers and their suppliers, the introduction of Article 62 of Law no. 27 dated 24th March 2012 is crucial, because, by facilitating and encouraging complaints by the interested parties, it should allow the developing of normal competitive dynamics within the food distribution sector, where companies should be free to enter the market using the tools at their disposal, without undue restrictions.

Thermal properties at Aespoe HRL. Analysis of distribution and scale factors

International Nuclear Information System (INIS)

Sundberg, Jan

2003-04-01

A thermal model for the Aespoe HRL as well as a general strategy for thermal modelling is under development. As a part of that work, thermal conductivities have been modelled from reference values of thermal conductivity of different minerals and from the mineral composition of all Aespoe samples in the Sicada database. The produced thermal conductivity database has been analysed in terms of frequency, type of distribution, spatial distribution, variogram etc. A correction factor has been estimated to compensate for discrepancies between measured and calculated values. The calculated values have been corrected according to measured values. The data has been analysed according to different rock types. However, there are uncertainties in the base material of rock classification, mainly due to problem to distinguish between Aespoe diorite and Aevroe granite, but also because of different classification systems. There is a relationship between thermal conductivity and density for the rock types at Aespoe. Equations of the relationship have been developed based on all thermal conductivity, heat capacity and density measurements. The equations have been tested on two bore holes at Aespoe with promising results. It may be possible to evaluate the spatial distribution of the thermal properties from density loggings. However, more work is needed to develop a complete model including the handling of high and low density zones. There is an insufficient knowledge in the variation of thermal properties at different scales. If the whole variation within a rock type is in the cm-m scale the thermal influence on the canister is small. This is due to the fact that the small-scale variation in thermal properties is mainly averaged out in the 5-10 m scale. If the main variation within rock types is in the 5-10 m scale there is probably a significant effect on the canister temperature. However, it is likely that the observed variation occurs in both these scales. Simulation has been

Scaled momentum distributions of charged particles in dijet photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-04-01

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb -1 . The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, Λ eff , and the LPHD parameter, κ ch , are extracted. (orig.)

Real-Time Monitoring System for a Utility-Scale Photovoltaic Power Plant.

Science.gov (United States)

Moreno-Garcia, Isabel M; Palacios-Garcia, Emilio J; Pallares-Lopez, Victor; Santiago, Isabel; Gonzalez-Redondo, Miguel J; Varo-Martinez, Marta; Real-Calvo, Rafael J

2016-05-26

There is, at present, considerable interest in the storage and dispatchability of photovoltaic (PV) energy, together with the need to manage power flows in real-time. This paper presents a new system, PV-on time, which has been developed to supervise the operating mode of a Grid-Connected Utility-Scale PV Power Plant in order to ensure the reliability and continuity of its supply. This system presents an architecture of acquisition devices, including wireless sensors distributed around the plant, which measure the required information. It is also equipped with a high-precision protocol for synchronizing all data acquisition equipment, something that is necessary for correctly establishing relationships among events in the plant. Moreover, a system for monitoring and supervising all of the distributed devices, as well as for the real-time treatment of all the registered information, is presented. Performances were analyzed in a 400 kW transformation center belonging to a 6.1 MW Utility-Scale PV Power Plant. In addition to monitoring the performance of all of the PV plant's components and detecting any failures or deviations in production, this system enables users to control the power quality of the signal injected and the influence of the installation on the distribution grid.

Real-Time Monitoring System for a Utility-Scale Photovoltaic Power Plant

Science.gov (United States)

Moreno-Garcia, Isabel M.; Palacios-Garcia, Emilio J.; Pallares-Lopez, Victor; Santiago, Isabel; Gonzalez-Redondo, Miguel J.; Varo-Martinez, Marta; Real-Calvo, Rafael J.

2016-01-01

There is, at present, considerable interest in the storage and dispatchability of photovoltaic (PV) energy, together with the need to manage power flows in real-time. This paper presents a new system, PV-on time, which has been developed to supervise the operating mode of a Grid-Connected Utility-Scale PV Power Plant in order to ensure the reliability and continuity of its supply. This system presents an architecture of acquisition devices, including wireless sensors distributed around the plant, which measure the required information. It is also equipped with a high-precision protocol for synchronizing all data acquisition equipment, something that is necessary for correctly establishing relationships among events in the plant. Moreover, a system for monitoring and supervising all of the distributed devices, as well as for the real-time treatment of all the registered information, is presented. Performances were analyzed in a 400 kW transformation center belonging to a 6.1 MW Utility-Scale PV Power Plant. In addition to monitoring the performance of all of the PV plant’s components and detecting any failures or deviations in production, this system enables users to control the power quality of the signal injected and the influence of the installation on the distribution grid. PMID:27240365

Real-Time Monitoring System for a Utility-Scale Photovoltaic Power Plant

Directory of Open Access Journals (Sweden)

Isabel M. Moreno-Garcia

2016-05-01

Full Text Available There is, at present, considerable interest in the storage and dispatchability of photovoltaic (PV energy, together with the need to manage power flows in real-time. This paper presents a new system, PV-on time, which has been developed to supervise the operating mode of a Grid-Connected Utility-Scale PV Power Plant in order to ensure the reliability and continuity of its supply. This system presents an architecture of acquisition devices, including wireless sensors distributed around the plant, which measure the required information. It is also equipped with a high-precision protocol for synchronizing all data acquisition equipment, something that is necessary for correctly establishing relationships among events in the plant. Moreover, a system for monitoring and supervising all of the distributed devices, as well as for the real-time treatment of all the registered information, is presented. Performances were analyzed in a 400 kW transformation center belonging to a 6.1 MW Utility-Scale PV Power Plant. In addition to monitoring the performance of all of the PV plant’s components and detecting any failures or deviations in production, this system enables users to control the power quality of the signal injected and the influence of the installation on the distribution grid.

Sequential Service Restoration for Unbalanced Distribution Systems and Microgrids

International Nuclear Information System (INIS)

Chen, Bo; Chen, Chen; Wang, Jianhui; Butler-Purry, Karen L.

2017-01-01

The resilience and reliability of modern power systems are threatened by increasingly severe weather events and cyber-physical security events. An effective restoration methodology is desired to optimally integrate emerging smart grid technologies and pave the way for developing self-healing smart grids. In this paper, a sequential service restoration (SSR) framework is proposed to generate restoration solutions for distribution systems and microgrids in the event of large-scale power outages. The restoration solution contains a sequence of control actions that properly coordinate switches, distributed generators, and switchable loads to form multiple isolated microgrids. The SSR can be applied for three-phase unbalanced distribution systems and microgrids and can adapt to various operation conditions. Mathematical models are introduced for three-phase unbalanced power flow, voltage regulators, transformers, and loads. Furthermore, the SSR problem is formulated as a mixed-integer linear programming model, and its effectiveness is evaluated via the modified IEEE 123 node test feeder.

Planning Systems for Distributed Operations

Science.gov (United States)

Maxwell, Theresa G.

2002-01-01

This viewgraph representation presents an overview of the mission planning process involving distributed operations (such as the International Space Station (ISS)) and the computer hardware and software systems needed to support such an effort. Topics considered include: evolution of distributed planning systems, ISS distributed planning, the Payload Planning System (PPS), future developments in distributed planning systems, Request Oriented Scheduling Engine (ROSE) and Next Generation distributed planning systems.

Fine-scale distribution of zooplankton is linked to phytoplankton species composition and abundance in a North Norwegian fjord system

Science.gov (United States)

Norrbin, F.; Priou, P. D.; Varela, A. P.

2016-02-01

We studied the influence of dense layers of phytoplankton and aggregates on shaping the vertical distribution of zooplankton in a North Norwegian fjord using a Video Plankton Recorder (VPR). This instrument provided fine-scale vertical distribution (cm-m scale) of planktonic organisms as well as aggregates of marine snow in relation to environmental conditions. At the height - later stage of the spring phytoplankton bloom in May, the outer part of the fjord was dominated by Phaeocystis pouchetii, while diatoms (Chaetoceros spp.) were dominating in the innermost basin. Small copepods species like Pseudocalanus spp., Microsetella norvegica, and Oithona spp. prevailed over larger copepod species in the inner part of the fjord whereas the outer part was dominated by large copepods like Calanus finmarchicus. While the zooplankton where spread out over the water column during the early stage of the bloom, in May they were linked to the phytoplankton vertical distribution and in the winter situation they were found in deeper waters. Herbivorous zooplankton species were affected by phytoplankton species composition; C. finmarchicus and Pseudocalanus spp. avoided the dense layer of P. pouchetii while herbivorous zooplankton matched the distribution of the diatom-dominated bloom. Small, omnivorous copepod species like Microsetella sp., Oithona sp. and Pseudocalanus sp. were often associated with dense layers of snow aggregates. This distribution may provide a shelter from predators as well as a food source. Natural or anthropogenic-induced changes in phytoplankton composition and aggregate distribution may thus influence food-web interactions.

Scaled momentum distributions of charged particles in dijet photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-04-15

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb{sup -1}. The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, {lambda}{sub eff}, and the LPHD parameter, {kappa}{sup ch}, are extracted. (orig.)

Reallocating risks and returns to scale up adoption of distributed electricity resources

International Nuclear Information System (INIS)

Kulatilaka, Nalin; Santiago, Leonardo; Vakili, Pirooz

2014-01-01

Deployment of distributed electricity resources requires bringing together assets that belong to diverse and geographically diffuse owners. Using the example of distributed solar PV, we analyze the schemes used to encourage/induce owners of distributed assets to make them available for electricity generation. The dominant model in the U.S. is long term power purchase agreements (PPA) offered to owners/consumers by solar developers. We show that these agreements (mis)allocate the electricity price risk to owners/consumers and impose limitations on the scale up of distributed solar. By proper use of financial markets it is possible to shift the electricity price risk from owners/consumers to parties that are better positioned to manage it. The proposed contracts simplify the adoption decision for owners/consumers and can lead to a wider adoption. Removing barriers to scale up requires (i) eliminating the tight coupling between consumers and owners and (ii) rewarding the owners unambiguously for the assets they provide. These necessitate the transformation of the current intermediary firms into full-fledged distributed generators. We discuss the implications of such a transformation and argue that the broad outline of our analysis can be used to assess scale up schemes in other domains of distributed electricity resources as well. - Highlights: • We analyze schemes used to induce owners of distributed assets to make them available for electricity generation. • We show that power purchase agreements used in solar PV “misallocate” electricity price risk to owners/consumers. • We propose new contracts forms that shift price risk from consumers to parties that are better able to manage it. • Full-fledged distributed generators are created by unambiguously rewarding owners and de-coupling consumption/ownership. • We argue that our analysis can be used to assess scale up schemes in other domains of distributed electricity resources

EDSN: A First Demonstration of a Distributed System of Nanosatellites

Science.gov (United States)

Hu, Steven Hung Kee; Smith, Harrison Brodsky

2013-01-01

Edison Demonstration of SmallSat Networks (EDSN) is the first demonstration of a distributed system of nano-scale satellites to use intersatellite communication while working towards common science and technology goals. This unique mission configuration poses key technological challenges, including multi-satellite deployment, close proximity flight, cross-satellite communications, and simplified and effective operations. Tackling these challenges has required extensive development on EDSNs guidance navigation and control (GNC) and flight software systems. Although use of COTS component is common to the CubeSat community, it is prudent to point out that utilization of these components enables EDSN to accomplish its objectives at relatively low cost ($12M) in comparison to current multi-satellite missions capable of cross-link communications. EDSN is on cost and schedule with flight unit shipment in August 2013. This paper aims to update the community of EDSN's progress since SRR and speaks to the approach EDSN has taken to resolve some of the main issues revolving around a distributed system of nano-scale satellites.

World-wide distribution automation systems

International Nuclear Information System (INIS)

Devaney, T.M.

1994-01-01

A worldwide power distribution automation system is outlined. Distribution automation is defined and the status of utility automation is discussed. Other topics discussed include a distribution management system, substation feeder, and customer functions, potential benefits, automation costs, planning and engineering considerations, automation trends, databases, system operation, computer modeling of system, and distribution management systems

Growing magma chambers control the distribution of small-scale flood basalts.

Science.gov (United States)

Yu, Xun; Chen, Li-Hui; Zeng, Gang

2015-11-19

Small-scale continental flood basalts are a global phenomenon characterized by regular spatio-temporal distributions. However, no genetic mechanism has been proposed to explain the visible but overlooked distribution patterns of these continental basaltic volcanism. Here we present a case study from eastern China, combining major and trace element analyses with Ar-Ar and K-Ar dating to show that the spatio-temporal distribution of small-scale flood basalts is controlled by the growth of long-lived magma chambers. Evolved basalts (SiO2 > 47.5 wt.%) from Xinchang-Shengzhou, a small-scale Cenozoic flood basalt field in Zhejiang province, eastern China, show a northward younging trend over the period 9.4-3.0 Ma. With northward migration, the magmas evolved only slightly ((Na2O + K2O)/MgO = 0.40-0.66; TiO2/MgO = 0.23-0.35) during about 6 Myr (9.4-3.3 Ma). When the flood basalts reached the northern end of the province, the magmas evolved rapidly (3.3-3.0 Ma) through a broad range of compositions ((Na2O + K2O)/MgO = 0.60-1.28; TiO2/MgO = 0.30-0.57). The distribution and two-stage compositional evolution of the migrating flood basalts record continuous magma replenishment that buffered against magmatic evolution and induced magma chamber growth. Our results demonstrate that the magma replenishment-magma chamber growth model explains the spatio-temporal distribution of small-scale flood basalts.

A new fluid distribution system for scale-flexible expanded bed adsorption

DEFF Research Database (Denmark)

Hubbuch, Jürgen; Heebøll-Nielsen, Anders; Hobley, Timothy John

2002-01-01

of axial dispersion was 6.1 x 10(-6) m(2) (.) s(-1) and 29 theoretical plates were measured. When the rotation rate was raised to 10 rpm, the coefficient of axial dispersion increased to 8.08 x 10(-6) m(2 .) s(-1) and the number of theoretical plates decreased to 22.......A new fluid distribution system designed for expanded bed adsorption was introduced and studied in a 150-cm diameter column. Based on fluid application through a rotating distributor, it eradicates the need for perforated plates, meshes, or local mixers. The effect of rotation rate on column...

Distributed Operating Systems

NARCIS (Netherlands)

Mullender, Sape J.

1987-01-01

In the past five years, distributed operating systems research has gone through a consolidation phase. On a large number of design issues there is now considerable consensus between different research groups. In this paper, an overview of recent research in distributed systems is given. In turn, the

Large-scale visualization system for grid environment

International Nuclear Information System (INIS)

Suzuki, Yoshio

2007-01-01

Center for Computational Science and E-systems of Japan Atomic Energy Agency (CCSE/JAEA) has been conducting R and Ds of distributed computing (grid computing) environments: Seamless Thinking Aid (STA), Information Technology Based Laboratory (ITBL) and Atomic Energy Grid InfraStructure (AEGIS). In these R and Ds, we have developed the visualization technology suitable for the distributed computing environment. As one of the visualization tools, we have developed the Parallel Support Toolkit (PST) which can execute the visualization process parallely on a computer. Now, we improve PST to be executable simultaneously on multiple heterogeneous computers using Seamless Thinking Aid Message Passing Interface (STAMPI). STAMPI, we have developed in these R and Ds, is the MPI library executable on a heterogeneous computing environment. The improvement realizes the visualization of extremely large-scale data and enables more efficient visualization processes in a distributed computing environment. (author)

Full Scale Drinking Water System Decontamination at the Water Security Test Bed

Data.gov (United States)

U.S. Environmental Protection Agency — The EPA’s Water Security Test Bed (WSTB) facility is a full-scale representation of a drinking water distribution system. In collaboration with the Idaho National...

Spatio-temporal assessment of food safety risks in Canadian food distribution systems using GIS.

Science.gov (United States)

Hashemi Beni, Leila; Villeneuve, Sébastien; LeBlanc, Denyse I; Côté, Kevin; Fazil, Aamir; Otten, Ainsley; McKellar, Robin; Delaquis, Pascal

2012-09-01

While the value of geographic information systems (GIS) is widely applied in public health there have been comparatively few examples of applications that extend to the assessment of risks in food distribution systems. GIS can provide decision makers with strong computing platforms for spatial data management, integration, analysis, querying and visualization. The present report addresses some spatio-analyses in a complex food distribution system and defines influence areas as travel time zones generated through road network analysis on a national scale rather than on a community scale. In addition, a dynamic risk index is defined to translate a contamination event into a public health risk as time progresses. More specifically, in this research, GIS is used to map the Canadian produce distribution system, analyze accessibility to contaminated product by consumers, and estimate the level of risk associated with a contamination event over time, as illustrated in a scenario. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Pervasive Electricity Distribution System

Directory of Open Access Journals (Sweden)

Muhammad Usman Tahir

2017-06-01

Full Text Available Now a days a country cannot become economically strong until and unless it has enough electrical power to fulfil industrial and domestic needs. Electrical power being the pillar of any country’s economy, needs to be used in an efficient way. The same step is taken here by proposing a new system for energy distribution from substation to consumer houses, also it monitors the consumer consumption and record data. Unlike traditional manual Electrical systems, pervasive electricity distribution system (PEDS introduces a fresh perspective to monitor the feeder line status at distribution and consumer level. In this system an effort is taken to address the issues of electricity theft, manual billing, online monitoring of electrical distribution system and automatic control of electrical distribution points. The project is designed using microcontroller and different sensors, its GUI is designed in Labview software.

A Performance Comparison of Tree and Ring Topologies in Distributed System

Energy Technology Data Exchange (ETDEWEB)

Huang, Min [Iowa State Univ., Ames, IA (United States)

2004-01-01

A distributed system is a collection of computers that are connected via a communication network. Distributed systems have become commonplace due to the wide availability of low-cost, high performance computers and network devices. However, the management infrastructure often does not scale well when distributed systems get very large. Some of the considerations in building a distributed system are the choice of the network topology and the method used to construct the distributed system so as to optimize the scalability and reliability of the system, lower the cost of linking nodes together and minimize the message delay in transmission, and simplify system resource management. We have developed a new distributed management system that is able to handle the dynamic increase of system size, detect and recover the unexpected failure of system services, and manage system resources. The topologies used in the system are the tree-structured network and the ring-structured network. This thesis presents the research background, system components, design, implementation, experiment results and the conclusions of our work. The thesis is organized as follows: the research background is presented in chapter 1. Chapter 2 describes the system components, including the different node types and different connection types used in the system. In chapter 3, we describe the message types and message formats in the system. We discuss the system design and implementation in chapter 4. In chapter 5, we present the test environment and results, Finally, we conclude with a summary and describe our future work in chapter 6.

Gluon distributions in nucleons and pions at a low resolution scale

International Nuclear Information System (INIS)

Christiansen, H.R.

2000-10-01

In this paper we study the gluon distribution functions in nucleons and pions at a low resolution Q 2 scale. This is an important issue since parton densities at low Q 2 have always been taken as an external input which is adjusted through DGLAP evolution to fit the experimental data at higher scales. Here, in the framework of a model recently developed, it is shown that the hypothetical cloud of neutral pions surrounding nucleons and pions appears to be responsible for the characteristic valence-like gluon distributions needed at the initial low scale. As an additional result, we get the remarkable prediction that neutral and charged ions have different intrinsic sea flavor contents. (author)

Multi-Scale Three-Dimensional Variational Data Assimilation System for Coastal Ocean Prediction

Science.gov (United States)

Li, Zhijin; Chao, Yi; Li, P. Peggy

2012-01-01

A multi-scale three-dimensional variational data assimilation system (MS-3DVAR) has been formulated and the associated software system has been developed for improving high-resolution coastal ocean prediction. This system helps improve coastal ocean prediction skill, and has been used in support of operational coastal ocean forecasting systems and field experiments. The system has been developed to improve the capability of data assimilation for assimilating, simultaneously and effectively, sparse vertical profiles and high-resolution remote sensing surface measurements into coastal ocean models, as well as constraining model biases. In this system, the cost function is decomposed into two separate units for the large- and small-scale components, respectively. As such, data assimilation is implemented sequentially from large to small scales, the background error covariance is constructed to be scale-dependent, and a scale-dependent dynamic balance is incorporated. This scheme then allows effective constraining large scales and model bias through assimilating sparse vertical profiles, and small scales through assimilating high-resolution surface measurements. This MS-3DVAR enhances the capability of the traditional 3DVAR for assimilating highly heterogeneously distributed observations, such as along-track satellite altimetry data, and particularly maximizing the extraction of information from limited numbers of vertical profile observations.

RF Phase Reference Distribution System for the TESLA Technology Based Projects

CERN Document Server

Czuba, K; Romaniuk, R S

2013-01-01

Since many decades physicists have been building particle accelerators and usually new projects became more advanced, more complicated and larger than predecessors. The importance and complexity of the phase reference distribution systems used in these accelerators have grown significantly during recent years. Amongst the most advanced of currently developed accelerators are projects based on the TESLA technology. These projects require synchronization of many RF devices with accuracy reaching femtosecond levels over kilometre distances. Design of a phase reference distribution system fulfilling such requirements is a challenging scientific task. There are many interdisciplinary problems which must be solved during the system design. Many, usually negligible issues, may became very important in such system. Furthermore, the design of a distribution system on a scale required for the TESLA technology based projects is a new challenge and there is almost no literature sufficiently covering this subject. This th...

The Future of Distributed Computing Systems in ATLAS: Boldly Venturing Beyond Grids

CERN Document Server

Barreiro Megino, Fernando Harald; The ATLAS collaboration

2018-01-01

The Production and Distributed Analysis system (PanDA) for the ATLAS experiment at the Large Hadron Collider has seen big changes over the past couple of years to accommodate new types of distributed computing resources: clouds, HPCs, volunteer computers and other external resources. While PanDA was originally designed for fairly homogeneous resources available through the Worldwide LHC Computing Grid, the new resources are heterogeneous, at diverse scales and with diverse interfaces. Up to a fifth of the resources available to ATLAS are of such new types and require special techniques for integration into PanDA. In this talk, we present the nature and scale of these resources. We provide an overview of the various challenges faced, spanning infrastructure, software distribution, workload requirements, scaling requirements, workflow management, data management, network provisioning, and associated software and computing facilities. We describe the strategies for integrating these heterogeneous resources into ...

Aggregated Representation of Distribution Networks for Large-Scale Transmission Network Simulations

DEFF Research Database (Denmark)

Göksu, Ömer; Altin, Müfit; Sørensen, Poul Ejnar

2014-01-01

As a common practice of large-scale transmission network analysis the distribution networks have been represented as aggregated loads. However, with increasing share of distributed generation, especially wind and solar power, in the distribution networks, it became necessary to include...... the distributed generation within those analysis. In this paper a practical methodology to obtain aggregated behaviour of the distributed generation is proposed. The methodology, which is based on the use of the IEC standard wind turbine models, is applied on a benchmark distribution network via simulations....

Critical evaluation and comparison of fluid distribution systems for industrial scale expanded bed adsorption chromatography columns

DEFF Research Database (Denmark)

Arpanaei, Ayyoob; Heebøll-Nielsen, Anders; Hubbuch, Jürgen

2008-01-01

distributor at large scale were apparent: dead zones were present which could not be removed by increasing rotation rates or flow rates, and such changes led to a deterioration in hydrodynamic properties. In contrast, during fluid introduction through a rotating distributor no dead zones were observed....... The results imply that further improvement in distributor design is needed and careful attention should be given to the trade off between turbulence and adequate fluid distribution....

Enabling the Analysis of Emergent Behavior in Future Electrical Distribution Systems Using Agent-Based Modeling and Simulation

Directory of Open Access Journals (Sweden)

Sonja Kolen

2018-01-01

Full Text Available In future electrical distribution systems, component heterogeneity and their cyber-physical interactions through electrical lines and communication lead to emergent system behavior. As the distribution systems represent the largest part of an energy system with respect to the number of nodes and components, large-scale studies of their emergent behavior are vital for the development of decentralized control strategies. This paper presents and evaluates DistAIX, a novel agent-based modeling and simulation tool to conduct such studies. The major novelty is a parallelization of the entire model—including the power system, communication system, control, and all interactions—using processes instead of threads. Thereby, a distribution of the simulation to multiple computing nodes with a distributed memory architecture becomes possible. This makes DistAIX scalable and allows the inclusion of as many processing units in the simulation as desired. The scalability of DistAIX is demonstrated by simulations of large-scale scenarios. Additionally, the capability of observing emergent behavior is demonstrated for an exemplary distribution grid with a large number of interacting components.

Optimizing queries in distributed systems

Directory of Open Access Journals (Sweden)

Ion LUNGU

2006-01-01

Full Text Available This research presents the main elements of query optimizations in distributed systems. First, data architecture according with system level architecture in a distributed environment is presented. Then the architecture of a distributed database management system (DDBMS is described on conceptual level followed by the presentation of the distributed query execution steps on these information systems. The research ends with presentation of some aspects of distributed database query optimization and strategies used for that.

On the Path to SunShot. Emerging Issues and Challenges in Integrating Solar with the Distribution System

Energy Technology Data Exchange (ETDEWEB)

Palmintier, Bryan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Broderick, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mather, Barry [National Renewable Energy Lab. (NREL), Golden, CO (United States); Coddington, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Baker, Kyri [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ding, Fei [National Renewable Energy Lab. (NREL), Golden, CO (United States); Reno, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lave, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bharatkumar, Ashwini [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2016-05-01

This report analyzes distribution-integration challenges, solutions, and research needs in the context of distributed generation from PV (DGPV) deployment to date and the much higher levels of deployment expected with achievement of the U.S. Department of Energy's SunShot targets. Recent analyses have improved estimates of the DGPV hosting capacities of distribution systems. This report uses these results to statistically estimate the minimum DGPV hosting capacity for the contiguous United States using traditional inverters of approximately 170 GW without distribution system modifications. This hosting capacity roughly doubles if advanced inverters are used to manage local voltage and additional minor, low-cost changes could further increase these levels substantially. Key to achieving these deployment levels at minimum cost is siting DGPV based on local hosting capacities, suggesting opportunities for regulatory, incentive, and interconnection innovation. Already, pre-computed hosting capacity is beginning to expedite DGPV interconnection requests and installations in select regions; however, realizing SunShot-scale deployment will require further improvements to DGPV interconnection processes, standards and codes, and compensation mechanisms so they embrace the contributions of DGPV to system-wide operations. SunShot-scale DGPV deployment will also require unprecedented coordination of the distribution and transmission systems. This includes harnessing DGPV's ability to relieve congestion and reduce system losses by generating closer to loads; minimizing system operating costs and reserve deployments through improved DGPV visibility; developing communication and control architectures that incorporate DGPV into system operations; providing frequency response, transient stability, and synthesized inertia with DGPV in the event of large-scale system disturbances; and potentially managing reactive power requirements due to large-scale deployment of advanced

Large-Scale Transport Model Uncertainty and Sensitivity Analysis: Distributed Sources in Complex Hydrogeologic Systems

International Nuclear Information System (INIS)

Sig Drellack, Lance Prothro

2007-01-01

The Underground Test Area (UGTA) Project of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office is in the process of assessing and developing regulatory decision options based on modeling predictions of contaminant transport from underground testing of nuclear weapons at the Nevada Test Site (NTS). The UGTA Project is attempting to develop an effective modeling strategy that addresses and quantifies multiple components of uncertainty including natural variability, parameter uncertainty, conceptual/model uncertainty, and decision uncertainty in translating model results into regulatory requirements. The modeling task presents multiple unique challenges to the hydrological sciences as a result of the complex fractured and faulted hydrostratigraphy, the distributed locations of sources, the suite of reactive and non-reactive radionuclides, and uncertainty in conceptual models. Characterization of the hydrogeologic system is difficult and expensive because of deep groundwater in the arid desert setting and the large spatial setting of the NTS. Therefore, conceptual model uncertainty is partially addressed through the development of multiple alternative conceptual models of the hydrostratigraphic framework and multiple alternative models of recharge and discharge. Uncertainty in boundary conditions is assessed through development of alternative groundwater fluxes through multiple simulations using the regional groundwater flow model. Calibration of alternative models to heads and measured or inferred fluxes has not proven to provide clear measures of model quality. Therefore, model screening by comparison to independently-derived natural geochemical mixing targets through cluster analysis has also been invoked to evaluate differences between alternative conceptual models. Advancing multiple alternative flow models, sensitivity of transport predictions to parameter uncertainty is assessed through Monte Carlo simulations. The

On the probability distribution of the stochastic saturation scale in QCD

International Nuclear Information System (INIS)

Marquet, C.; Soyez, G.; Xiao Bowen

2006-01-01

It was recently noticed that high-energy scattering processes in QCD have a stochastic nature. An event-by-event scattering amplitude is characterised by a saturation scale which is a random variable. The statistical ensemble of saturation scales formed with all the events is distributed according to a probability law whose cumulants have been recently computed. In this work, we obtain the probability distribution from the cumulants. We prove that it can be considered as Gaussian over a large domain that we specify and our results are confirmed by numerical simulations

Design and Implementation of Distributed Crawler System Based on Scrapy

Science.gov (United States)

Fan, Yuhao

2018-01-01

At present, some large-scale search engines at home and abroad only provide users with non-custom search services, and a single-machine web crawler cannot sovle the difficult task. In this paper, Through the study and research of the original Scrapy framework, the original Scrapy framework is improved by combining Scrapy and Redis, a distributed crawler system based on Web information Scrapy framework is designed and implemented, and Bloom Filter algorithm is applied to dupefilter modul to reduce memory consumption. The movie information captured from douban is stored in MongoDB, so that the data can be processed and analyzed. The results show that distributed crawler system based on Scrapy framework is more efficient and stable than the single-machine web crawler system.

Energy Management of Smart Distribution Systems

Science.gov (United States)

Ansari, Bananeh

Electric power distribution systems interface the end-users of electricity with the power grid. Traditional distribution systems are operated in a centralized fashion with the distribution system owner or operator being the only decision maker. The management and control architecture of distribution systems needs to gradually transform to accommodate the emerging smart grid technologies, distributed energy resources, and active electricity end-users or prosumers. The content of this document concerns with developing multi-task multi-objective energy management schemes for: 1) commercial/large residential prosumers, and 2) distribution system operator of a smart distribution system. The first part of this document describes a method of distributed energy management of multiple commercial/ large residential prosumers. These prosumers not only consume electricity, but also generate electricity using their roof-top solar photovoltaics systems. When photovoltaics generation is larger than local consumption, excess electricity will be fed into the distribution system, creating a voltage rise along the feeder. Distribution system operator cannot tolerate a significant voltage rise. ES can help the prosumers manage their electricity exchanges with the distribution system such that minimal voltage fluctuation occurs. The proposed distributed energy management scheme sizes and schedules each prosumer's ES to reduce the electricity bill and mitigate voltage rise along the feeder. The second part of this document focuses on emergency energy management and resilience assessment of a distribution system. The developed emergency energy management system uses available resources and redundancy to restore the distribution system's functionality fully or partially. The success of the restoration maneuver depends on how resilient the distribution system is. Engineering resilience terminology is used to evaluate the resilience of distribution system. The proposed emergency energy

Evaluation of Corba for use in distributed control systems

International Nuclear Information System (INIS)

Holloway, F.W.; Arsdall, P. van

1999-01-01

The Common Object Request Broker Architecture (CORBA)-based Simulator was a Laboratory Directed Research and Development (LDRD) project that applied simulation techniques to explore critical questions about advanced distributed control system architectures. A three-prong approach comprised of a study of object-oriented distribution tools, computer network modeling, and simulation of key control system scenarios was used in the LDRD project. This input report describes the first of the three approaches the study of object-oriented distribution tools together with measurements, and predictions of use within the National Ignition Facility (NIF) and some aspects of CORBA which remain to be resolved. For the ICCS, the completeness of suitable functionality, the speed of performance and utilization of machine and network resources, and the developing nature of the commercial CORBA products themselves, presented a certain risk. This LDRD thus evaluated CORBA in general, and a particular implementation, to determine its features, performance, and scaling properties, and to optimize its use within the ICCS. Both UNIX and real-time operating systems were studied

Scale-dependent bias from the reconstruction of non-Gaussian distributions

International Nuclear Information System (INIS)

Chongchitnan, Sirichai; Silk, Joseph

2011-01-01

Primordial non-Gaussianity introduces a scale-dependent variation in the clustering of density peaks corresponding to rare objects. This variation, parametrized by the bias, is investigated on scales where a linear perturbation theory is sufficiently accurate. The bias is obtained directly in real space by comparing the one- and two-point probability distributions of density fluctuations. We show that these distributions can be reconstructed using a bivariate Edgeworth series, presented here up to an arbitrarily high order. The Edgeworth formalism is shown to be well-suited for ''local'' cubic-order non-Gaussianity parametrized by g NL . We show that a strong scale dependence in the bias can be produced by g NL of order 10 5 , consistent with cosmic microwave background constraints. On a separation length of ∼100 Mpc, current constraints on g NL still allow the bias for the most massive clusters to be enhanced by 20-30% of the Gaussian value. We further examine the bias as a function of mass scale, and also explore the relationship between the clustering and the abundance of massive clusters in the presence of g NL . We explain why the Edgeworth formalism, though technically challenging, is a very powerful technique for constraining high-order non-Gaussianity with large-scale structures.

Design of improved fuel cell controller for distributed generation systems

Energy Technology Data Exchange (ETDEWEB)

Olsen Berenguer, F.A. [Instituto de Energia Electrica, Universidad Nacional de San Juan, Av. Libertador San Martin Oeste, 1109, J5400ARL San Juan (Argentina); Molina, M.G. [CONICET, Instituto de Energia Electrica, Universidad Nacional de San Juan, Av. Libertador San Martin Oeste, 1109, J5400ARL San Juan (Argentina)

2010-06-15

The world has been undergoing a deregulation process which allowed competition in the electricity generation sector. This situation is bringing the opportunity for electricity users to generate power by using small-scale generation systems with emerging technologies, allowing the development of distributed generation (DG). A fuel cell power plant (FCPP) is a distributed generation technology with a rapid development because it has promising characteristics, such as low pollutant emissions, silent operation, high efficiency and long lifetime because of its small number of moving parts. The power conditioning system (PCS) is the interface that allows the effective connection to the electric power system. With the appropriate topology of the PCS and its control system design, the FCPP unit is capable of simultaneously performing both instantaneous active and reactive power flow control. This paper describes the design and implementation of a novel high performance PCS of an FCPP and its controller, for applications in distributed generation systems. A full detailed model of the FCPP is derived and a new three-level control scheme is designed. The dynamic performance of the proposed system is validated by digital simulation in SimPowerSystems (SPS) of MATLAB/Simulink. (author)

Thermal Distribution System | Energy Systems Integration Facility | NREL

Science.gov (United States)

Thermal Distribution System Thermal Distribution System The Energy Systems Integration Facility's . Photo of the roof of the Energy Systems Integration Facility. The thermal distribution bus allows low as 10% of its full load level). The 60-ton chiller cools water with continuous thermal control

Entanglement scaling in lattice systems

Energy Technology Data Exchange (ETDEWEB)

Audenaert, K M R [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom); Cramer, M [QOLS, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Eisert, J [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom); Plenio, M B [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom)

2007-05-15

We review some recent rigorous results on scaling laws of entanglement properties in quantum many body systems. More specifically, we study the entanglement of a region with its surrounding and determine its scaling behaviour with its size for systems in the ground and thermal states of bosonic and fermionic lattice systems. A theorem connecting entanglement between a region and the rest of the lattice with the surface area of the boundary between the two regions is presented for non-critical systems in arbitrary spatial dimensions. The entanglement scaling in the field limit exhibits a peculiar difference between fermionic and bosonic systems. In one-spatial dimension a logarithmic divergence is recovered for both bosonic and fermionic systems. In two spatial dimensions in the setting of half-spaces however we observe strict area scaling for bosonic systems and a multiplicative logarithmic correction to such an area scaling in fermionic systems. Similar questions may be posed and answered in classical systems.

Scaling of Precipitation Extremes Modelled by Generalized Pareto Distribution

Science.gov (United States)

Rajulapati, C. R.; Mujumdar, P. P.

2017-12-01

Precipitation extremes are often modelled with data from annual maximum series or peaks over threshold series. The Generalized Pareto Distribution (GPD) is commonly used to fit the peaks over threshold series. Scaling of precipitation extremes from larger time scales to smaller time scales when the extremes are modelled with the GPD is burdened with difficulties arising from varying thresholds for different durations. In this study, the scale invariance theory is used to develop a disaggregation model for precipitation extremes exceeding specified thresholds. A scaling relationship is developed for a range of thresholds obtained from a set of quantiles of non-zero precipitation of different durations. The GPD parameters and exceedance rate parameters are modelled by the Bayesian approach and the uncertainty in scaling exponent is quantified. A quantile based modification in the scaling relationship is proposed for obtaining the varying thresholds and exceedance rate parameters for shorter durations. The disaggregation model is applied to precipitation datasets of Berlin City, Germany and Bangalore City, India. From both the applications, it is observed that the uncertainty in the scaling exponent has a considerable effect on uncertainty in scaled parameters and return levels of shorter durations.

Galaxies distribution in the universe: large-scale statistics and structures

International Nuclear Information System (INIS)

Maurogordato, Sophie

1988-01-01

This research thesis addresses the distribution of galaxies in the Universe, and more particularly large scale statistics and structures. Based on an assessment of the main used statistical techniques, the author outlines the need to develop additional tools to correlation functions in order to characterise the distribution. She introduces a new indicator: the probability of a volume randomly tested in the distribution to be void. This allows a characterisation of void properties at the work scales (until 10h"-"1 Mpc) in the Harvard Smithsonian Center for Astrophysics Redshift Survey, or CfA catalog. A systematic analysis of statistical properties of different sub-samples has then been performed with respect to the size and location, luminosity class, and morphological type. This analysis is then extended to different scenarios of structure formation. A program of radial speed measurements based on observations allows the determination of possible relationships between apparent structures. The author also presents results of the search for south extensions of Perseus supernova [fr

Vehicle-to-Grid Systems for Frequency Regulation in an Islanded Danish Distribution Network

DEFF Research Database (Denmark)

Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

2010-01-01

vehicles could provide power system ancillary services in the form of power balancing reserves to support the large-scale integration of variable renewable energy sources like wind power. This paper investigates the dynamic frequency response of an islanded Danish distribution system operation with large...

Robust receding horizon control for networked and distributed nonlinear systems

CERN Document Server

Li, Huiping

2017-01-01

This book offers a comprehensive, easy-to-understand overview of receding-horizon control for nonlinear networks. It presents novel general strategies that can simultaneously handle general nonlinear dynamics, system constraints, and disturbances arising in networked and large-scale systems and which can be widely applied. These receding-horizon-control-based strategies can achieve sub-optimal control performance while ensuring closed-loop stability: a feature attractive to engineers. The authors address the problems of networked and distributed control step-by-step, gradually increasing the level of challenge presented. The book first introduces the state-feedback control problems of nonlinear networked systems and then studies output feedback control problems. For large-scale nonlinear systems, disturbance is considered first, then communication delay separately, and lastly the simultaneous combination of delays and disturbances. Each chapter of this easy-to-follow book not only proposes and analyzes novel ...

Large-scale digitizer system, analog converters

International Nuclear Information System (INIS)

Althaus, R.F.; Lee, K.L.; Kirsten, F.A.; Wagner, L.J.

1976-10-01

Analog to digital converter circuits that are based on the sharing of common resources, including those which are critical to the linearity and stability of the individual channels, are described. Simplicity of circuit composition is valued over other more costly approaches. These are intended to be applied in a large-scale processing and digitizing system for use with high-energy physics detectors such as drift-chambers or phototube-scintillator arrays. Signal distribution techniques are of paramount importance in maintaining adequate signal-to-noise ratio. Noise in both amplitude and time-jitter senses is held sufficiently low so that conversions with 10-bit charge resolution and 12-bit time resolution are achieved

Distributed systems

CERN Document Server

Van Steen, Maarten

2017-01-01

For this third edition of "Distributed Systems," the material has been thoroughly revised and extended, integrating principles and paradigms into nine chapters: 1. Introduction 2. Architectures 3. Processes 4. Communication 5. Naming 6. Coordination 7. Replication 8. Fault tolerance 9. Security A separation has been made between basic material and more specific subjects. The latter have been organized into boxed sections, which may be skipped on first reading. To assist in understanding the more algorithmic parts, example programs in Python have been included. The examples in the book leave out many details for readability, but the complete code is available through the book's Website, hosted at www.distributed-systems.net.

Drinking Water Distribution Systems

Science.gov (United States)

Learn about an overview of drinking water distribution systems, the factors that degrade water quality in the distribution system, assessments of risk, future research about these risks, and how to reduce cross-connection control risk.

Quantifying Carbon and distributional benefits of solar home system programs in Bangladesh

OpenAIRE

Wang, Limin; Bandyopadhyay, Sushenjit; Cosgrove-Davies, Mac; Samad, Hussain

2011-01-01

Scaling-up adoption of renewable energy technology, such as solar home systems, to expand electricity access in developing countries can accelerate the transition to low-carbon economic development. Using a purposely collected national household survey, this study quantifies the carbon and distributional benefits of solar home system programs in Bangladesh. Three key findings are generated...

Identification and characterization of steady and occluded water in drinking water distribution systems.

Science.gov (United States)

Tong, Huiyan; Zhao, Peng; Zhang, Hongwei; Tian, Yimei; Chen, Xi; Zhao, Weigao; Li, Mei

2015-01-01

Deterioration and leakage of drinking water in distribution systems have been a major issue in the water industry for years, which are associated with corrosion. This paper discovers that occluded water in the scales of the pipes has an acidic environment and high concentration of iron, manganese, chloride, sulfate and nitrate, which aggravates many pipeline leakage accidents. Six types of water samples have been analyzed under the flowing and stagnant periods. Both the water in the exterior of the tubercles and stagnant water carry suspended iron particles, which explains the occurrence of "red water" when the system hydraulic conditions change. Nitrate is more concentrated in occluded water under flowing condition in comparison with that in flowing water. However, the concentration of nitrate in occluded water under stagnant condition is found to be less than that in stagnant water. A high concentration of manganese is found to exist in steady water, occluded water and stagnant water. These findings impact secondary pollution and the corrosion of pipes and containers used in drinking water distribution systems. The unique method that taking occluded water from tiny holes which were drilled from the pipes' exteriors carefully according to the positions of corrosion scales has an important contribution to research on corrosion in distribution systems. And this paper furthers our understanding and contributes to the growing body of knowledge regarding occluded environments in corrosion scales. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distributed security in closed distributed systems

DEFF Research Database (Denmark)

Hernandez, Alejandro Mario

properties. This is also restricted to distributed systems in which the set of locations is known a priori. All this follows techniques borrowed from both the model checking and the static analysis communities. In the end, we reach a step towards solving the problem of enforcing security in distributed...... systems. We achieve the goal of showing how this can be done, though we restrict ourselves to closed systems and with a limited set of enforceable security policies. In this setting, our approach proves to be efficient. Finally, we achieve all this by bringing together several fields of Computer Science......The goal of the present thesis is to discuss, argue and conclude about ways to provide security to the information travelling around computer systems consisting of several known locations. When developing software systems, security of the information managed by these plays an important role...

Distribution system modeling and analysis

CERN Document Server

Kersting, William H

2001-01-01

For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that allow engineers to simulate, analyze, and optimize distribution systems. Powerful as these programs are, however, without a real understanding of the operating characteristics of a distribution system, engineers using the programs can easily make serious errors in their designs and operating procedures. Distribution System Modeling and Analysis helps prevent those errors. It gives readers a basic understanding of the modeling and operating characteristics of the major components of a distribution system. One by one, the author develops and analyzes each component as a stand-alone element, then puts them all together to analyze a distribution system comprising the various shunt and series devices for power-flow and short-circuit studies. He includes the derivation of all models and includes many num...

A distribution management system

Energy Technology Data Exchange (ETDEWEB)

Jaerventausta, P; Verho, P; Kaerenlampi, M; Pitkaenen, M [Tampere Univ. of Technology (Finland); Partanen, J [Lappeenranta Univ. of Technology (Finland)

1998-08-01

The development of new distribution automation applications is considerably wide nowadays. One of the most interesting areas is the development of a distribution management system (DMS) as an expansion to the traditional SCADA system. At the power transmission level such a system is called an energy management system (EMS). The idea of these expansions is to provide supporting tools for control center operators in system analysis and operation planning. Nowadays the SCADA is the main computer system (and often the only) in the control center. However, the information displayed by the SCADA is often inadequate, and several tasks cannot be solved by a conventional SCADA system. A need for new computer applications in control center arises from the insufficiency of the SCADA and some other trends. The latter means that the overall importance of the distribution networks is increasing. The slowing down of load-growth has often made network reinforcements unprofitable. Thus the existing network must be operated more efficiently. At the same time larger distribution areas are for economical reasons being monitored at one control center and the size of the operation staff is decreasing. The quality of supply requirements are also becoming stricter. The needed data for new applications is mainly available in some existing systems. Thus the computer systems of utilities must be integrated. The main data source for the new applications in the control center are the AM/FM/GIS (i.e. the network database system), the SCADA, and the customer information system (CIS). The new functions can be embedded in some existing computer system. This means a strong dependency on the vendor of the existing system. An alternative strategy is to develop an independent system which is integrated with other computer systems using well-defined interfaces. The latter approach makes it possible to use the new applications in various computer environments, having only a weak dependency on the

Simulation Model developed for a Small-Scale PV-System in a Distribution Network

DEFF Research Database (Denmark)

Koch-Ciobotaru, C.; Mihet-Popa, Lucian; Isleifsson, Fridrik Rafn

2012-01-01

This paper presents a PV panel simulation model using the single-diode four-parameter model based on data sheet values. The model was implemented first in MATLAB/Simulink, and the results have been compared with the data sheet values and characteristics of the PV panels in standard test condition...... and implemented in PowerFactory to study load flow, steady-state voltage stability and dynamic behavior of a distributed power system....

Cross-Scale Value Trade-Offs in Managing Social-Ecological Systems: The Politics of Scale in Ruaha National Park, Tanzania

Directory of Open Access Journals (Sweden)

Asim Zia

2011-12-01

Full Text Available Management of social-ecological systems takes place amidst complex governance processes and cross-scale institutional arrangements that are mediated through politics of scale. Each management scenario generates distinct cross-scale trade-offs in the distribution of pluralistic values. This study explores the hypothesis that conservation-oriented management scenarios generate higher value for international and national scale social organizations, whereas mixed or more balanced management scenarios generate higher value for local scale social organizations. This hypothesis is explored in the management context of Ruaha National Park (RNP, Tanzania, especially the 2006 expansion of RNP that led to the eviction of many pastoralists and farmers. Five management scenarios for RNP, i.e., national park, game reserve, game control area, multiple use area, and open area, are evaluated in a multicriteria decision analytical framework on six valuation criteria: economic welfare; good governance; socio-cultural values; social equity; ecosystem services; and biodiversity protection; and at three spatial scales: local, national, and international. Based upon this evaluation, we discuss the politics of scale that ensue from the implementation of management alternatives with different mixes of conservation and development goals in social-ecological systems.

Cooling water distribution system

Science.gov (United States)

Orr, Richard

1994-01-01

A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

Recommendations for scale-up of community-based misoprostol distribution programs.

Science.gov (United States)

Robinson, Nuriya; Kapungu, Chisina; Carnahan, Leslie; Geller, Stacie

2014-06-01

Community-based distribution of misoprostol for prevention of postpartum hemorrhage (PPH) in resource-poor settings has been shown to be safe and effective. However, global recommendations for prenatal distribution and monitoring within a community setting are not yet available. In order to successfully translate misoprostol and PPH research into policy and practice, several critical points must be considered. A focus on engaging the community, emphasizing the safe nature of community-based misoprostol distribution, supply chain management, effective distribution, coverage, and monitoring plans are essential elements to community-based misoprostol program introduction, expansion, or scale-up. Copyright © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Representative elements: A step to large-scale fracture system simulation

International Nuclear Information System (INIS)

Clemo, T.M.

1987-01-01

Large-scale simulation of flow and transport in fractured media requires the development of a technique to represent the effect of a large number of fractures. Representative elements are used as a tool to model a subset of a fracture system as a single distributed entity. Representative elements are part of a modeling concept called dual permeability. Dual permeability modeling combines discrete fracture simulation of the most important fractures with the distributed modeling of the less important fracture of a fracture system. This study investigates the use of stochastic analysis to determine properties of representative elements. Given an assumption of fully developed laminar flow, the net fracture conductivities and hence flow velocities can be determined from descriptive statistics of fracture spacing, orientation, aperture, and extent. The distribution of physical characteristics about their mean leads to a distribution of the associated conductivities. The variance of hydraulic conductivity induces dispersion into the transport process. Simple fracture systems are treated to demonstrate the usefulness of stochastic analysis. Explicit equations for conductivity of an element are developed and the dispersion characteristics are shown. Explicit formulation of the hydraulic conductivity and transport dispersion reveals the dependence of these important characteristics on the parameters used to describe the fracture system. Understanding these dependencies will help to focus efforts to identify the characteristics of fracture systems. Simulations of stochastically generated fracture sets do not provide this explicit functional dependence on the fracture system parameters. 12 refs., 6 figs

The scaling of stress distribution under small scale yielding by T-scaling method and application to prediction of the temperature dependence on fracture toughness

International Nuclear Information System (INIS)

Ishihara, Kenichi; Hamada, Takeshi; Meshii, Toshiyuki

2017-01-01

In this paper, a new method for scaling the crack tip stress distribution under small scale yielding condition was proposed and named as T-scaling method. This method enables to identify the different stress distributions for materials with different tensile properties but identical load in terms of K or J. Then by assuming that the temperature dependence of a material is represented as the stress-strain relationship temperature dependence, a method to predict the fracture load at an arbitrary temperature from the already known fracture load at a reference temperature was proposed. This method combined the T-scaling method and the knowledge “fracture stress for slip induced cleavage fracture is temperature independent.” Once the fracture load is predicted, fracture toughness J c at the temperature under consideration can be evaluated by running elastic-plastic finite element analysis. Finally, the above-mentioned framework to predict the J c temperature dependency of a material in the ductile-to-brittle temperature distribution was validated for 0.55% carbon steel JIS S55C. The proposed framework seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests. (author)

Continuously distributed magnetization profile for millimeter-scale elastomeric undulatory swimming

Science.gov (United States)

Diller, Eric; Zhuang, Jiang; Zhan Lum, Guo; Edwards, Matthew R.; Sitti, Metin

2014-04-01

We have developed a millimeter-scale magnetically driven swimming robot for untethered motion at mid to low Reynolds numbers. The robot is propelled by continuous undulatory deformation, which is enabled by the distributed magnetization profile of a flexible sheet. We demonstrate control of a prototype device and measure deformation and speed as a function of magnetic field strength and frequency. Experimental results are compared with simple magnetoelastic and fluid propulsion models. The presented mechanism provides an efficient remote actuation method at the millimeter scale that may be suitable for further scaling down in size for micro-robotics applications in biotechnology and healthcare.

Evolution of the ATLAS Distributed Computing system during the LHC Long shutdown

CERN Document Server

Campana, S; The ATLAS collaboration

2014-01-01

The ATLAS Distributed Computing project (ADC) was established in 2007 to develop and operate a framework, following the ATLAS computing model, to enable data storage, processing and bookkeeping on top of the WLCG distributed infrastructure. ADC development has always been driven by operations and this contributed to its success. The system has fulfilled the demanding requirements of ATLAS, daily consolidating worldwide up to 1PB of data and running more than 1.5 million payloads distributed globally, supporting almost one thousand concurrent distributed analysis users. Comprehensive automation and monitoring minimized the operational manpower required. The flexibility of the system to adjust to operational needs has been important to the success of the ATLAS physics program. The LHC shutdown in 2013-2015 affords an opportunity to improve the system in light of operational experience and scale it to cope with the demanding requirements of 2015 and beyond, most notably a much higher trigger rate and event pileu...

Sea-ice floe-size distribution in the context of spontaneous scaling emergence in stochastic systems

Science.gov (United States)

Herman, Agnieszka

2010-06-01

Sea-ice floe-size distribution (FSD) in ice-pack covered seas influences many aspects of ocean-atmosphere interactions. However, data concerning FSD in the polar oceans are still sparse and processes shaping the observed FSD properties are poorly understood. Typically, power-law FSDs are assumed although no feasible explanation has been provided neither for this one nor for other properties of the observed distributions. Consequently, no model exists capable of predicting FSD parameters in any particular situation. Here I show that the observed FSDs can be well represented by a truncated Pareto distribution P(x)=x-1-αexp[(1-α)/x] , which is an emergent property of a certain group of multiplicative stochastic systems, described by the generalized Lotka-Volterra (GLV) equation. Building upon this recognition, a possibility of developing a simple agent-based GLV-type sea-ice model is considered. Contrary to simple power-law FSDs, GLV gives consistent estimates of the total floe perimeter, as well as floe-area distribution in agreement with observations.

Scaling of multiplicity distribution in hadron collisions and diffractive-excitation like models

International Nuclear Information System (INIS)

Buras, A.J.; Dethlefsen, J.M.; Koba, Z.

1974-01-01

Multiplicity distribution of secondary particles in inelastic hadron collision at high energy is studied in the semiclassical impact parameter representation. The scaling function is shown to consist of two factors: one geometrical and the other dynamical. We propose a specific choice of these factors, which describe satisfactorily the elastic scattering, the ratio of elastic to total cross-section and the simple scaling behaviour of multiplicity distribution in p-p collisions. Two versions of diffractive-excitation like models (global and local excitation) are presented as interpretation of our choice of dynamical factor. (author)

High Voltage Distribution System (HVDS) as a better system compared to Low Voltage Distribution System (LVDS) applied at Medan city power network

Science.gov (United States)

Dinzi, R.; Hamonangan, TS; Fahmi, F.

2018-02-01

In the current distribution system, a large-capacity distribution transformer supplies loads to remote locations. The use of 220/380 V network is nowadays less common compared to 20 kV network. This results in losses due to the non-optimal distribution transformer, which neglected the load location, poor consumer profile, and large power losses along the carrier. This paper discusses how high voltage distribution systems (HVDS) can be a better system used in distribution networks than the currently used distribution system (Low Voltage Distribution System, LVDS). The proposed change of the system into the new configuration is done by replacing a large-capacity distribution transformer with some smaller-capacity distribution transformers and installed them in positions that closest to the load. The use of high voltage distribution systems will result in better voltage profiles and fewer power losses. From the non-technical side, the annual savings and payback periods on high voltage distribution systems will also be the advantage.

Multi-Time Scale Coordinated Scheduling Strategy with Distributed Power Flow Controllers for Minimizing Wind Power Spillage

Directory of Open Access Journals (Sweden)

Yi Tang

2017-11-01

Full Text Available The inherent variability and randomness of large-scale wind power integration have brought great challenges to power flow control and dispatch. The distributed power flow controller (DPFC has the higher flexibility and capacity in power flow control in the system with wind generation. This paper proposes a multi-time scale coordinated scheduling model with DPFC to minimize wind power spillage. Configuration of DPFCs is initially determined by stochastic method. Afterward, two sequential procedures containing day-head and real-time scales are applied for determining maximum schedulable wind sources, optimal outputs of generating units and operation setting of DPFCs. The generating plan is obtained initially in day-ahead scheduling stage and modified in real-time scheduling model, while considering the uncertainty of wind power and fast operation of DPFC. Numerical simulation results in IEEE-RTS79 system illustrate that wind power is maximum scheduled with the optimal deployment and operation of DPFC, which confirms the applicability and effectiveness of the proposed method.

Landslide scaling and magnitude-frequency distribution (Invited)

Science.gov (United States)

Stark, C. P.; Guzzetti, F.

2009-12-01

Landslide-driven erosion is controlled by the scale and frequency of slope failures and by the consequent fluxes of debris off the hillslopes. Here I focus on the magnitude-frequency part of the process and develop a theory of initial slope failure and debris mobilization that reproduces the heavy-tailed distributions (PDFs) observed for landslide source areas and volumes. Landslide rupture propagation is treated as a quasi-static, non-inertial process of simplified elastoplastic deformation with strain weakening; debris runout is not considered. The model tracks the stochastically evolving imbalance of frictional, cohesive, and body forces across a failing slope, and uses safety-factor concepts to convert the evolving imbalance into a series of incremental rupture growth or arrest probabilities. A single rupture is simulated with a sequence of weighted ``coin tosses'' with weights set by the growth probabilities. Slope failure treated in this stochastic way is a survival process that generates asymptotically power-law-tail PDFs of area and volume for rock and debris slides; predicted scaling exponents are consistent with analyses of landslide inventories. The primary control on the shape of the model PDFs is the relative importance of cohesion over friction in setting slope stability: the scaling of smaller, shallower failures, and the size of the most common landslide volumes, are the result of the low cohesion of soil and regolith, whereas the negative power-law tail scaling for larger failures is tied to the greater cohesion of bedrock. The debris budget may be dominated by small or large landslides depending on the scaling of both the PDF and of the depth-length relation. I will present new model results that confirm the hypothesis that depth-length scaling is linear. Model PDF of landslide volumes.

Scaling laws and indications of self-organized criticality in urban systems

International Nuclear Information System (INIS)

Chen Yanguang; Zhou Yixing

2008-01-01

Evolution of urban systems has been considered to exhibit some form of self-organized criticality (SOC) in the literature. This paper provides further mathematical foundations and empirical evidences to support the supposition. The hierarchical structure of systems of cities can be formulated as three exponential functions: the number law, the population size law, and the area law. These laws are identical in form to the Horton-Strahler laws of rivers and Gutenberg-Richter laws of earthquakes. From the exponential functions, three indications of SOC are also derived: the frequency-spectrum relation indicting the 1/f noise, the power laws indicating the fractal structure, and the Zipf's law indicating the rank-size distribution. These mathematical models form a set of scaling laws for urban systems, as demonstrated in the empirical study of the system of cities in China. The fact that the scaling laws of urban systems bear an analogy to those on rivers and earthquakes lends further support to the notion of possible SOC in urban systems

Dependence of exponents on text length versus finite-size scaling for word-frequency distributions

Science.gov (United States)

Corral, Álvaro; Font-Clos, Francesc

2017-08-01

Some authors have recently argued that a finite-size scaling law for the text-length dependence of word-frequency distributions cannot be conceptually valid. Here we give solid quantitative evidence for the validity of this scaling law, using both careful statistical tests and analytical arguments based on the generalized central-limit theorem applied to the moments of the distribution (and obtaining a novel derivation of Heaps' law as a by-product). We also find that the picture of word-frequency distributions with power-law exponents that decrease with text length [X. Yan and P. Minnhagen, Physica A 444, 828 (2016), 10.1016/j.physa.2015.10.082] does not stand with rigorous statistical analysis. Instead, we show that the distributions are perfectly described by power-law tails with stable exponents, whose values are close to 2, in agreement with the classical Zipf's law. Some misconceptions about scaling are also clarified.

Quality monitored distributed voting system

Science.gov (United States)

Skogmo, David

1997-01-01

A quality monitoring system can detect certain system faults and fraud attempts in a distributed voting system. The system uses decoy voters to cast predetermined check ballots. Absent check ballots can indicate system faults. Altered check ballots can indicate attempts at counterfeiting votes. The system can also cast check ballots at predetermined times to provide another check on the distributed voting system.

Multi-scale approach for predicting fish species distributions across coral reef seascapes.

Directory of Open Access Journals (Sweden)

Simon J Pittman

Full Text Available Two of the major limitations to effective management of coral reef ecosystems are a lack of information on the spatial distribution of marine species and a paucity of data on the interacting environmental variables that drive distributional patterns. Advances in marine remote sensing, together with the novel integration of landscape ecology and advanced niche modelling techniques provide an unprecedented opportunity to reliably model and map marine species distributions across many kilometres of coral reef ecosystems. We developed a multi-scale approach using three-dimensional seafloor morphology and across-shelf location to predict spatial distributions for five common Caribbean fish species. Seascape topography was quantified from high resolution bathymetry at five spatial scales (5-300 m radii surrounding fish survey sites. Model performance and map accuracy was assessed for two high performing machine-learning algorithms: Boosted Regression Trees (BRT and Maximum Entropy Species Distribution Modelling (MaxEnt. The three most important predictors were geographical location across the shelf, followed by a measure of topographic complexity. Predictor contribution differed among species, yet rarely changed across spatial scales. BRT provided 'outstanding' model predictions (AUC = >0.9 for three of five fish species. MaxEnt provided 'outstanding' model predictions for two of five species, with the remaining three models considered 'excellent' (AUC = 0.8-0.9. In contrast, MaxEnt spatial predictions were markedly more accurate (92% map accuracy than BRT (68% map accuracy. We demonstrate that reliable spatial predictions for a range of key fish species can be achieved by modelling the interaction between the geographical location across the shelf and the topographic heterogeneity of seafloor structure. This multi-scale, analytic approach is an important new cost-effective tool to accurately delineate essential fish habitat and support

Real time computer system with distributed microprocessors

International Nuclear Information System (INIS)

Heger, D.; Steusloff, H.; Syrbe, M.

1979-01-01

The usual centralized structure of computer systems, especially of process computer systems, cannot sufficiently use the progress of very large-scale integrated semiconductor technology with respect to increasing the reliability and performance and to decreasing the expenses especially of the external periphery. This and the increasing demands on process control systems has led the authors to generally examine the structure of such systems and to adapt it to the new surroundings. Computer systems with distributed, optical fibre-coupled microprocessors allow a very favourable problem-solving with decentralized controlled buslines and functional redundancy with automatic fault diagnosis and reconfiguration. A fit programming system supports these hardware properties: PEARL for multicomputer systems, dynamic loader, processor and network operating system. The necessary design principles for this are proved mainly theoretically and by value analysis. An optimal overall system of this new generation of process control systems was established, supported by results of 2 PDV projects (modular operating systems, input/output colour screen system as control panel), for the purpose of testing by apllying the system for the control of 28 pit furnaces of a steel work. (orig.) [de

Corrosion and Scaling Potential in Drinking Water Distribution of Babol, Northern Iran Based on the Scaling and Corrosion Indices

Directory of Open Access Journals (Sweden)

Abdoliman Amouei

2017-01-01

Full Text Available Background & Aims of the Study: Corrosion and scaling play undesirable effects on transmission and distribution system of drinking water. The aim of this study was to assess the corrosion and scaling potential of drinking water resources in Babol city, Iran. Materials and Methods: Totally, 54 water samples were collected from 27 wells in spring and autumn. Calcium hardness, pH, total alkalinity, total dissolved solids, and temperature were measured, using standard methods. The Langelier, Rayzner, Puckhorius, Larson and aggressive indices were calculated and data were analyzed by SPSS 19. To compare the mean values of each index, the results were analyzed using t-test. Results: The range of temperature, pH, TDS, total alkalinity and calcium hardness were 16-24°c; 6.8-7.89; 445-1331 mg/l; 322.9-396 mg/l and 250.50-490 mg/l, respectively. The mean of Langelier and Ryznar indices in drinking water samples in spring and autumn was 0.14, 0.15; 7.28 and 7.35, respectively. The mean of Puckhorius and Larson indices in these seasons was 11.9, 11.95 and 0.95 and 0.93, respectively. The mean of aggressive index was 6.17 and 6.27, respectively. Overall, 82.2%, 100%, 94.6%, 100% and 85.7% of water samples were corrosive based on the Langelier, Ryznar, Puckhorius, Larson and aggressive indices, respectively. Conclusion: According to these results, drinking water of Babol city has corrosion potential. Therefore, the water quality should be controlled based on pH, alkalinity and hardness parameters, along with the use of corrosion resisting materials and pipes in drinking water distribution systems.

The ATLAS distributed analysis system

OpenAIRE

Legger, F.

2014-01-01

In the LHC operations era, analysis of the multi-petabyte ATLAS data sample by globally distributed physicists is a challenging task. To attain the required scale the ATLAS Computing Model was designed around the concept of grid computing, realized in the Worldwide LHC Computing Grid (WLCG), the largest distributed computational resource existing in the sciences. The ATLAS experiment currently stores over 140 PB of data and runs about 140,000 concurrent jobs continuously at WLCG sites. During...

A distribution management system

Energy Technology Data Exchange (ETDEWEB)

Verho, P.; Jaerventausta, P.; Kaerenlampi, M.; Paulasaari, H. [Tampere Univ. of Technology (Finland); Partanen, J. [Lappeenranta Univ. of Technology (Finland)

1996-12-31

The development of new distribution automation applications is considerably wide nowadays. One of the most interesting areas is the development of a distribution management system (DMS) as an expansion of the traditional SCADA system. At the power transmission level such a system is called an energy management system (EMS). The idea of these expansions is to provide supporting tools for control center operators in system analysis and operation planning. The needed data for new applications is mainly available in some existing systems. Thus the computer systems of utilities must be integrated. The main data source for the new applications in the control center are the AM/FM/GIS (i.e. the network database system), the SCADA, and the customer information system (CIS). The new functions can be embedded in some existing computer system. This means a strong dependency on the vendor of the existing system. An alternative strategy is to develop an independent system which is integrated with other computer systems using well-defined interfaces. The latter approach makes it possible to use the new applications in various computer environments, having only a weak dependency on the vendors of the other systems. In the research project this alternative is preferred and used in developing an independent distribution management system

A distribution management system

Energy Technology Data Exchange (ETDEWEB)

Verho, P; Jaerventausta, P; Kaerenlampi, M; Paulasaari, H [Tampere Univ. of Technology (Finland); Partanen, J [Lappeenranta Univ. of Technology (Finland)

1997-12-31

The development of new distribution automation applications is considerably wide nowadays. One of the most interesting areas is the development of a distribution management system (DMS) as an expansion of the traditional SCADA system. At the power transmission level such a system is called an energy management system (EMS). The idea of these expansions is to provide supporting tools for control center operators in system analysis and operation planning. The needed data for new applications is mainly available in some existing systems. Thus the computer systems of utilities must be integrated. The main data source for the new applications in the control center are the AM/FM/GIS (i.e. the network database system), the SCADA, and the customer information system (CIS). The new functions can be embedded in some existing computer system. This means a strong dependency on the vendor of the existing system. An alternative strategy is to develop an independent system which is integrated with other computer systems using well-defined interfaces. The latter approach makes it possible to use the new applications in various computer environments, having only a weak dependency on the vendors of the other systems. In the research project this alternative is preferred and used in developing an independent distribution management system

RBAC Administration in Distributed Systems

NARCIS (Netherlands)

Dekker, M.A.C.; Crampton, J.; Etalle, Sandro

2007-01-01

Despite a large body of literature on the administration of RBAC policies in centralized systems, the problem of the administration of a distributed system has hardly been addressed. We present a formal system for modelling a distributed RBAC system and its administration. We define two basic

Design of distributed systems of hydrolithosphere processes management. A synthesis of distributed management systems

Science.gov (United States)

Pershin, I. M.; Pervukhin, D. A.; Ilyushin, Y. V.; Afanaseva, O. V.

2017-10-01

The paper considers an important problem of designing distributed systems of hydrolithosphere processes management. The control actions on the hydrolithosphere processes under consideration are implemented by a set of extractive wells. The article shows the method of defining the approximation links for description of the dynamic characteristics of hydrolithosphere processes. The structure of distributed regulators, used in the management systems by the considered processes, is presented. The paper analyses the results of the synthesis of the distributed management system and the results of modelling the closed-loop control system by the parameters of the hydrolithosphere process.

Multi-Time Scale Control of Demand Flexibility in Smart Distribution Networks

Directory of Open Access Journals (Sweden)

Bishnu P. Bhattarai

2017-01-01

Full Text Available This paper presents a multi-timescale control strategy to deploy electric vehicle (EV demand flexibility for simultaneously providing power balancing, grid congestion management, and economic benefits to participating actors. First, an EV charging problem is investigated from consumer, aggregator, and distribution system operator’s perspectives. A hierarchical control architecture (HCA comprising scheduling, coordinative, and adaptive layers is then designed to realize their coordinative goal. This is realized by integrating multi-time scale controls that work from a day-ahead scheduling up to real-time adaptive control. The performance of the developed method is investigated with high EV penetration in a typical residential distribution grid. The simulation results demonstrate that HCA efficiently utilizes demand flexibility stemming from EVs to solve grid unbalancing and congestions with simultaneous maximization of economic benefits to the participating actors. This is ensured by enabling EV participation in day-ahead, balancing, and regulation markets. For the given network configuration and pricing structure, HCA ensures the EV owners to get paid up to five times the cost they were paying without control.

Data Recovery of Distributed Hash Table with Distributed-to-Distributed Data Copy

Science.gov (United States)

Doi, Yusuke; Wakayama, Shirou; Ozaki, Satoshi

To realize huge-scale information services, many Distributed Hash Table (DHT) based systems have been proposed. For example, there are some proposals to manage item-level product traceability information with DHTs. In such an application, each entry of a huge number of item-level IDs need to be available on a DHT. To ensure data availability, the soft-state approach has been employed in previous works. However, this does not scale well against the number of entries on a DHT. As we expect 1010 products in the traceability case, the soft-state approach is unacceptable. In this paper, we propose Distributed-to-Distributed Data Copy (D3C). With D3C, users can reconstruct the data as they detect data loss, or even migrate to another DHT system. We show why it scales well against the number of entries on a DHT. We have confirmed our approach with a prototype. Evaluation shows our approach fits well on a DHT with a low rate of failure and a huge number of data entries.

Distributed design approach in persistent identifiers systems

Science.gov (United States)

Golodoniuc, Pavel; Car, Nicholas; Klump, Jens

2017-04-01

The need to identify both digital and physical objects is ubiquitous in our society. Past and present persistent identifier (PID) systems, of which there is a great variety in terms of technical and social implementations, have evolved with the advent of the Internet, which has allowed for globally unique and globally resolvable identifiers. PID systems have catered for identifier uniqueness, integrity, persistence, and trustworthiness, regardless of the identifier's application domain, the scope of which has expanded significantly in the past two decades. Since many PID systems have been largely conceived and developed by small communities, or even a single organisation, they have faced challenges in gaining widespread adoption and, most importantly, the ability to survive change of technology. This has left a legacy of identifiers that still exist and are being used but which have lost their resolution service. We believe that one of the causes of once successful PID systems fading is their reliance on a centralised technical infrastructure or a governing authority. Golodoniuc et al. (2016) proposed an approach to the development of PID systems that combines the use of (a) the Handle system, as a distributed system for the registration and first-degree resolution of persistent identifiers, and (b) the PID Service (Golodoniuc et al., 2015), to enable fine-grained resolution to different information object representations. The proposed approach solved the problem of guaranteed first-degree resolution of identifiers, but left fine-grained resolution and information delivery under the control of a single authoritative source, posing risk to the long-term availability of information resources. Herein, we develop these approaches further and explore the potential of large-scale decentralisation at all levels: (i) persistent identifiers and information resources registration; (ii) identifier resolution; and (iii) data delivery. To achieve large-scale decentralisation

Communication Facilities for Distributed Systems

Directory of Open Access Journals (Sweden)

V. Barladeanu

1997-01-01

Full Text Available The design of physical networks and communication protocols in Distributed Systems can have a direct impact on system efficiency and reliability. This paper tries to identify efficient mechanisms and paradigms for communication in distributed systems.

Control and operation of distributed generation in distribution systems

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2011-01-01

Many distribution systems nowadays have significant penetration of distributed generation (DG)and thus, islanding operation of these distribution systems is becoming a viable option for economical and technical reasons. The DG should operate optimally during both grid-connected and island...... algorithm, which uses average rate of change off requency (Af5) and real power shift RPS), in the islanded mode. RPS will increase or decrease the power set point of the generator with increasing or decreasing system frequency, respectively. Simulation results show that the proposed method can operate...

Underfrequency Load Shedding for an Islanded Distribution System With Distributed Generators

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

Significant penetration of distributed generation in many distribution systems has opened an option of operating distribution systems in island mode for economical and technical reasons. However, balancing frequency of the islanded system is still an issue to be solved, especially when the demand...

Research on distributed virtual reality system in electronic commerce

Science.gov (United States)

Xue, Qiang; Wang, Jiening; Sun, Jizhou

2004-03-01

In this paper, Distributed Virtual Reality (DVR) technology applied in Electronical Commerce (EC) is discussed. DVR has the capability of providing a new means for human being to recognize, analyze and resolve the large scale, complex problems, which makes it develop quickly in EC fields. The technology of CSCW (Computer Supported Cooperative Work) and middleware is introduced into the development of EC-DVR system to meet the need of a platform which can provide the necessary cooperation and communication services to avoid developing the basic module repeatedly. Finally, the paper gives a platform structure of EC-DVR system.

Loss Allocation in a Distribution System with Distributed Generation Units

DEFF Research Database (Denmark)

Lund, Torsten; Nielsen, Arne Hejde; Sørensen, Poul Ejnar

2007-01-01

In Denmark, a large part of the electricity is produced by wind turbines and combined heat and power plants (CHPs). Most of them are connected to the network through distribution systems. This paper presents a new algorithm for allocation of the losses in a distribution system with distributed...... generation. The algorithm is based on a reduced impedance matrix of the network and current injections from loads and production units. With the algorithm, the effect of the covariance between production and consumption can be evaluated. To verify the theoretical results, a model of the distribution system...

Fault tolerant distributed real time computer systems for I and C of prototype fast breeder reactor

Energy Technology Data Exchange (ETDEWEB)

Manimaran, M., E-mail: maran@igcar.gov.in; Shanmugam, A.; Parimalam, P.; Murali, N.; Satya Murty, S.A.V.

2014-03-15

Highlights: • Architecture of distributed real time computer system (DRTCS) used in I and C of PFBR is explained. • Fault tolerant (hot standby) architecture, fault detection and switch over are detailed. • Scaled down model was used to study functional and performance requirements of DRTCS. • Quality of service parameters for scaled down model was critically studied. - Abstract: Prototype fast breeder reactor (PFBR) is in the advanced stage of construction at Kalpakkam, India. Three-tier architecture is adopted for instrumentation and control (I and C) of PFBR wherein bottom tier consists of real time computer (RTC) systems, middle tier consists of process computers and top tier constitutes of display stations. These RTC systems are geographically distributed and networked together with process computers and display stations. Hot standby architecture comprising of dual redundant RTC systems with switch over logic system is deployed in order to achieve fault tolerance. Fault tolerant dual redundant network connectivity is provided in each RTC system and TCP/IP protocol is selected for network communication. In order to assess the performance of distributed RTC systems, scaled down model was developed with 9 representative systems and nearly 15% of I and C signals of PFBR were connected and monitored. Functional and performance testing were carried out for each RTC system and the fault tolerant characteristics were studied by creating various faults into the system and observed the performance. Various quality of service parameters like connection establishment delay, priority parameter, transit delay, throughput, residual error ratio, etc., are critically studied for the network.

Sea-ice floe-size distribution in the context of spontaneous scaling emergence in stochastic systems.

Science.gov (United States)

Herman, Agnieszka

2010-06-01

Sea-ice floe-size distribution (FSD) in ice-pack covered seas influences many aspects of ocean-atmosphere interactions. However, data concerning FSD in the polar oceans are still sparse and processes shaping the observed FSD properties are poorly understood. Typically, power-law FSDs are assumed although no feasible explanation has been provided neither for this one nor for other properties of the observed distributions. Consequently, no model exists capable of predicting FSD parameters in any particular situation. Here I show that the observed FSDs can be well represented by a truncated Pareto distribution P(x)=x(-1-α) exp[(1-α)/x] , which is an emergent property of a certain group of multiplicative stochastic systems, described by the generalized Lotka-Volterra (GLV) equation. Building upon this recognition, a possibility of developing a simple agent-based GLV-type sea-ice model is considered. Contrary to simple power-law FSDs, GLV gives consistent estimates of the total floe perimeter, as well as floe-area distribution in agreement with observations.

Corroded scale analysis from water distribution pipes

Directory of Open Access Journals (Sweden)

Rajaković-Ognjanović Vladana N.

2011-01-01

Full Text Available The subject of this study was the steel pipes that are part of Belgrade's drinking water supply network. In order to investigate the mutual effects of corrosion and water quality, the corrosion scales on the pipes were analyzed. The idea was to improve control of corrosion processes and prevent impact of corrosion on water quality degradation. The instrumental methods for corrosion scales characterization used were: scanning electron microscopy (SEM, for the investigation of corrosion scales of the analyzed samples surfaces, X-ray diffraction (XRD, for the analysis of the presence of solid forms inside scales, scanning electron microscopy (SEM, for the microstructural analysis of the corroded scales, and BET adsorption isotherm for the surface area determination. Depending on the composition of water next to the pipe surface, corrosion of iron results in the formation of different compounds and solid phases. The composition and structure of the iron scales in the drinking water distribution pipes depends on the type of the metal and the composition of the aqueous phase. Their formation is probably governed by several factors that include water quality parameters such as pH, alkalinity, buffer intensity, natural organic matter (NOM concentration, and dissolved oxygen (DO concentration. Factors such as water flow patterns, seasonal fluctuations in temperature, and microbiological activity as well as water treatment practices such as application of corrosion inhibitors can also influence corrosion scale formation and growth. Therefore, the corrosion scales found in iron and steel pipes are expected to have unique features for each site. Compounds that are found in iron corrosion scales often include goethite, lepidocrocite, magnetite, hematite, ferrous oxide, siderite, ferrous hydroxide, ferric hydroxide, ferrihydrite, calcium carbonate and green rusts. Iron scales have characteristic features that include: corroded floor, porous core that contains

Asellus aquaticus and other invertebrates in drinking water distribution systems

DEFF Research Database (Denmark)

Christensen, Sarah Christine

hygiene. Whereas invertebrates in drinking water are known to host parasites in tropical countries they are largely regarded an aesthetical problem in temperate countries. Publications on invertebrate distribution in Danish systems have been completely absent and while reports from various countries have...... other crustaceans and nematodes protect bacteria from treatment processes. The influence of A. aquaticus has never previously been investigated. Investigations in this PhD project revealed that presence of A. aquaticus did not influence microbial water quality measurably in full scale distribution...... Campylobacter jejuni. Invertebrates enter drinking water systems through various routes e.g. through deficiencies in e.g. tanks, pipes, valves and fittings due to bursts or maintenance works. Some invertebrates pass treatment processes from ground water or surface water supplies while other routes may include...

Resource Provisioning in Large-Scale Self-Organizing Distributed Systems

Science.gov (United States)

2012-06-01

organizations. Due to scale, competition, and advertising revenues, services such as email, social networking, office document processing, file storage and...53] fastCGI, http://www.fastcgi.com/. 205 [54] B. Adida , “It all starts at the server [5.World Wide Web and FastCGI],” IEEE Internet

SCALE Code System

Energy Technology Data Exchange (ETDEWEB)

Jessee, Matthew Anderson [ORNL

2016-04-01

The SCALE Code System is a widely-used modeling and simulation suite for nuclear safety analysis and design that is developed, maintained, tested, and managed by the Reactor and Nuclear Systems Division (RNSD) of Oak Ridge National Laboratory (ORNL). SCALE provides a comprehensive, verified and validated, user-friendly tool set for criticality safety, reactor and lattice physics, radiation shielding, spent fuel and radioactive source term characterization, and sensitivity and uncertainty analysis. Since 1980, regulators, licensees, and research institutions around the world have used SCALE for safety analysis and design. SCALE provides an integrated framework with dozens of computational modules including three deterministic and three Monte Carlo radiation transport solvers that are selected based on the desired solution strategy. SCALE includes current nuclear data libraries and problem-dependent processing tools for continuous-energy (CE) and multigroup (MG) neutronics and coupled neutron-gamma calculations, as well as activation, depletion, and decay calculations. SCALE includes unique capabilities for automated variance reduction for shielding calculations, as well as sensitivity and uncertainty analysis. SCALE’s graphical user interfaces assist with accurate system modeling, visualization of nuclear data, and convenient access to desired results.SCALE 6.2 provides many new capabilities and significant improvements of existing features.New capabilities include:• ENDF/B-VII.1 nuclear data libraries CE and MG with enhanced group structures,• Neutron covariance data based on ENDF/B-VII.1 and supplemented with ORNL data,• Covariance data for fission product yields and decay constants,• Stochastic uncertainty and correlation quantification for any SCALE sequence with Sampler,• Parallel calculations with KENO,• Problem-dependent temperature corrections for CE calculations,• CE shielding and criticality accident alarm system analysis with MAVRIC,• CE

The Location-Scale Mixture Exponential Power Distribution: A Bayesian and Maximum Likelihood Approach

OpenAIRE

Rahnamaei, Z.; Nematollahi, N.; Farnoosh, R.

2012-01-01

We introduce an alternative skew-slash distribution by using the scale mixture of the exponential power distribution. We derive the properties of this distribution and estimate its parameter by Maximum Likelihood and Bayesian methods. By a simulation study we compute the mentioned estimators and their mean square errors, and we provide an example on real data to demonstrate the modeling strength of the new distribution.

Robust Distributed Model Predictive Load Frequency Control of Interconnected Power System

Directory of Open Access Journals (Sweden)

Xiangjie Liu

2013-01-01

Full Text Available Considering the load frequency control (LFC of large-scale power system, a robust distributed model predictive control (RDMPC is presented. The system uncertainty according to power system parameter variation alone with the generation rate constraints (GRC is included in the synthesis procedure. The entire power system is composed of several control areas, and the problem is formulated as convex optimization problem with linear matrix inequalities (LMI that can be solved efficiently. It minimizes an upper bound on a robust performance objective for each subsystem. Simulation results show good dynamic response and robustness in the presence of power system dynamic uncertainties.

Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season.

Science.gov (United States)

Warwick-Evans, Victoria C; Atkinson, Philip W; Robinson, Leonie A; Green, Jonathan A

2016-01-01

During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney's coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney's seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making.

Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season.

Directory of Open Access Journals (Sweden)

Victoria C Warwick-Evans

Full Text Available During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney's coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney's seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making.

Millimeter-scale MEMS enabled autonomous systems: system feasibility and mobility

Science.gov (United States)

Pulskamp, Jeffrey S.

2012-06-01

Millimeter-scale robotic systems based on highly integrated microelectronics and micro-electromechanical systems (MEMS) could offer unique benefits and attributes for small-scale autonomous systems. This extreme scale for robotics will naturally constrain the realizable system capabilities significantly. This paper assesses the feasibility of developing such systems by defining the fundamental design trade spaces between component design variables and system level performance parameters. This permits the development of mobility enabling component technologies within a system relevant context. Feasible ranges of system mass, required aerodynamic power, available battery power, load supported power, flight endurance, and required leg load bearing capability are presented for millimeter-scale platforms. The analysis illustrates the feasibility of developing both flight capable and ground mobile millimeter-scale autonomous systems while highlighting the significant challenges that must be overcome to realize their potential.

Scaling-Laws of Flow Entropy with Topological Metrics of Water Distribution Networks

Directory of Open Access Journals (Sweden)

Giovanni Francesco Santonastaso

2018-01-01

Full Text Available Robustness of water distribution networks is related to their connectivity and topological structure, which also affect their reliability. Flow entropy, based on Shannon’s informational entropy, has been proposed as a measure of network redundancy and adopted as a proxy of reliability in optimal network design procedures. In this paper, the scaling properties of flow entropy of water distribution networks with their size and other topological metrics are studied. To such aim, flow entropy, maximum flow entropy, link density and average path length have been evaluated for a set of 22 networks, both real and synthetic, with different size and topology. The obtained results led to identify suitable scaling laws of flow entropy and maximum flow entropy with water distribution network size, in the form of power–laws. The obtained relationships allow comparing the flow entropy of water distribution networks with different size, and provide an easy tool to define the maximum achievable entropy of a specific water distribution network. An example of application of the obtained relationships to the design of a water distribution network is provided, showing how, with a constrained multi-objective optimization procedure, a tradeoff between network cost and robustness is easily identified.

Small‐scale distribution of fish in offshore windfarms

DEFF Research Database (Denmark)

Hansen, Kamilla Sande; Stenberg, Claus; Møller, Peter Rask

2012-01-01

Knowledge about small‐scale distribution of fish around turbines in offshore windfarms (OWF) remains relatively scarce. In the present study we used underwater video camera installations to access abundance of fish at 0, 25, and 50 m around the turbine foundations in Middelgrund and Lillgrund OWFs...... in Øresund between Denmark and Sweden in the period August–November 2011. Fish fauna in both localities were dominated in terms of numbers by two‐spotted gobies (Gobiusculus flavescens). Average number of fish observed per hour was a factor 100 higher at Lillgrund and a factor of 2 higher at Middelgrund at 0...... on fish fauna compared to OWFs in areas with heterogeneous sediment. Furthermore, the effect of OWFs on fish appears to be of a much smaller scale than previously thought...

Calcium Carbonate Formation in Water Distribution Systems and Autogenous Repair of Leaks by Inert Particle Clogging

OpenAIRE

Richards, Colin Scott

2016-01-01

The formation of calcium carbonate (CaCO3) (i.e. scale) in potable water systems has long been a concern in water treatment and distribution. A literature review reveals that CaCO3 scaling issues are re-emerging due to climate change, temperature increases in hot water systems and lower use of scaling and corrosion inhibitors. Moreover, we have gathered insights that suggest CaCO3 coatings can be beneficial and stop pipeline leaks via self-repair or clogging. Ironically, the actions we are ta...

Distributed systems status and control

Science.gov (United States)

Kreidler, David; Vickers, David

1990-01-01

Concepts are investigated for an automated status and control system for a distributed processing environment. System characteristics, data requirements for health assessment, data acquisition methods, system diagnosis methods and control methods were investigated in an attempt to determine the high-level requirements for a system which can be used to assess the health of a distributed processing system and implement control procedures to maintain an accepted level of health for the system. A potential concept for automated status and control includes the use of expert system techniques to assess the health of the system, detect and diagnose faults, and initiate or recommend actions to correct the faults. Therefore, this research included the investigation of methods by which expert systems were developed for real-time environments and distributed systems. The focus is on the features required by real-time expert systems and the tools available to develop real-time expert systems.

Analysis of distribution systems with a high penetration of distributed generation

DEFF Research Database (Denmark)

Lund, Torsten

Since the mid eighties, a large number of wind turbines and distributed combined heat and power plants (CHPs) have been connected to the Danish power system. Especially in the Western part, comprising Jutland and Funen, the penetration is high compared to the load demand. In some periods the wind...... power alone can cover the entire load demand. The objective of the work is to investigate the influence of wind power and distributed combined heat and power production on the operation of the distribution systems. Where other projects have focused on the modeling and control of the generators and prime...... movers, the focus of this project is on the operation of an entire distribution system with several wind farms and CHPs. Firstly, the subject of allocation of power system losses in a distribution system with distributed generation is treated. A new approach to loss allocation based on current injections...

The Location-Scale Mixture Exponential Power Distribution: A Bayesian and Maximum Likelihood Approach

Directory of Open Access Journals (Sweden)

Z. Rahnamaei

2012-01-01

Full Text Available We introduce an alternative skew-slash distribution by using the scale mixture of the exponential power distribution. We derive the properties of this distribution and estimate its parameter by Maximum Likelihood and Bayesian methods. By a simulation study we compute the mentioned estimators and their mean square errors, and we provide an example on real data to demonstrate the modeling strength of the new distribution.

A systematic approach for the assessment of bacterial growth-controlling factors linked to biological stability of drinking water in distribution systems

KAUST Repository

Prest, E. I.

2016-01-06

A systematic approach is presented for the assessment of (i) bacterial growth-controlling factors in drinking water and (ii) the impact of distribution conditions on the extent of bacterial growth in full-scale distribution systems. The approach combines (i) quantification of changes in autochthonous bacterial cell concentrations in full-scale distribution systems with (ii) laboratoryscale batch bacterial growth potential tests of drinking water samples under defined conditions. The growth potential tests were done by direct incubation of water samples, without modification of the original bacterial flora, and with flow cytometric quantification of bacterial growth. This method was shown to be reproducible (ca. 4% relative standard deviation) and sensitive (detection of bacterial growth down to 5 μg L-1 of added assimilable organic carbon). The principle of step-wise assessment of bacterial growth-controlling factors was demonstrated on bottled water, shown to be primarily carbon limited at 133 (±18) × 103 cells mL-1 and secondarily limited by inorganic nutrients at 5,500 (±1,700) × 103 cells mL-1. Analysis of the effluent of a Dutch full-scale drinking water treatment plant showed (1) bacterial growth inhibition as a result of end-point chlorination, (2) organic carbon limitation at 192 (±72) × 103 cells mL-1 and (3) inorganic nutrient limitation at 375 (±31) × 103 cells mL-1. Significantly lower net bacterial growth was measured in the corresponding full-scale distribution system (176 (±25) × 103 cells mL-1) than in the laboratory-scale growth potential test of the same water (294 (±35) × 103 cells mL-1), highlighting the influence of distribution on bacterial growth. The systematic approach described herein provides quantitative information on the effect of drinking water properties and distribution system conditions on biological stability, which can assist water utilities in decision-making on treatment or distribution system improvements to

Evaluating the Sustainability of a Small-Scale Low-Input Organic Vegetable Supply System in the United Kingdom

DEFF Research Database (Denmark)

Markussen, Mads Ville; Kulak, Michal; Smith, Laurence G.

2014-01-01

Resource use and environmental impacts of a small-scale low-input organic vegetable supply system in the United Kingdom were assessed by emergy accounting and Life Cycle Assessment (LCA). The system consisted of a farm with high crop diversity and a related box-scheme distribution system. We...... compared empirical data from this case system with two modeled organic food supply systems representing high-and low-yielding practices for organic vegetable production. Further, these systems were embedded in a supermarket distribution system and they provided the same amount of comparable vegetables...

A Simple Adaptive Overcurrent Protection of Distribution Systems With Distributed Generation

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2011-01-01

current when the system is connected to the grid and when it is islanded. This paper proposes the use of adaptive protection, using local information, to overcome the challenges of the overcurrent protection in distribution systems with distributed generation. The trip characteristics of the relays...... are updated by detecting operating states (grid connected or island) and the faulted section. The paper also proposes faulted section detection using the time over-current characteristics of the protective relays. Simulation results show that the operating state and faulted section can be correctly identified......A significant increase in the penetration of distributed generation has resulted in a possibility of operating distribution systems with distributed generation in islanded mode. However, over-current protection of an islanded distribution system is still an issue due to the difference in fault...

Distributed Treatment Systems.

Science.gov (United States)

Zgonc, David; Plante, Luke

2017-10-01

This section presents a review of the literature published in 2016 on topics relating to distributed treatment systems. This review is divided into the following sections with multiple subsections under each: constituent removal; treatment technologies; and planning and treatment system management.

The Impact of Connecting Distributed Generation to the Distribution System

Directory of Open Access Journals (Sweden)

E. V. Mgaya

2007-01-01

Full Text Available This paper deals with the general problem of utilizing of renewable energy sources to generate electric energy. Recent advances in renewable energy power generation technologies, e.g., wind and photovoltaic (PV technologies, have led to increased interest in the application of these generation devices as distributed generation (DG units. This paper presents the results of an investigation into possible improvements in the system voltage profile and reduction of system losses when adding wind power DG (wind-DG to a distribution system. Simulation results are given for a case study, and these show that properly sized wind DGs, placed at carefully selected sites near key distribution substations, could be very effective in improving the distribution system voltage profile and reducing power losses, and hence could  improve the effective capacity of the system. 

Large-scale Complex IT Systems

OpenAIRE

Sommerville, Ian; Cliff, Dave; Calinescu, Radu; Keen, Justin; Kelly, Tim; Kwiatkowska, Marta; McDermid, John; Paige, Richard

2011-01-01

This paper explores the issues around the construction of large-scale complex systems which are built as 'systems of systems' and suggests that there are fundamental reasons, derived from the inherent complexity in these systems, why our current software engineering methods and techniques cannot be scaled up to cope with the engineering challenges of constructing such systems. It then goes on to propose a research and education agenda for software engineering that identifies the major challen...

Large-scale complex IT systems

OpenAIRE

Sommerville, Ian; Cliff, Dave; Calinescu, Radu; Keen, Justin; Kelly, Tim; Kwiatkowska, Marta; McDermid, John; Paige, Richard

2012-01-01

12 pages, 2 figures This paper explores the issues around the construction of large-scale complex systems which are built as 'systems of systems' and suggests that there are fundamental reasons, derived from the inherent complexity in these systems, why our current software engineering methods and techniques cannot be scaled up to cope with the engineering challenges of constructing such systems. It then goes on to propose a research and education agenda for software engineering that ident...

Evaluation small scale, grid connected wind and solar distributed generation systems in Jordan

International Nuclear Information System (INIS)

Naji, G. J.; Tahboub, K. K.; Jalham, I. S.

2011-01-01

In this paper, the potential of utilizing wind and solar Private Distributed Generation (PDG) for utility interactive systems is investigated for 11 selected stations (sites) in Jordan. Six customer categories are considered: residential, office, commercial mall, school, hospital and hotel. The main goal of this study was to evaluate the potential of utilizing different grid connected PDG under different conditions such as their location, size, served building category, number of people who share and own the equipment and system type whether wind, solar or hybrid based. It was found that solar systems are still not attractive for all location due to their associated high cost, while wind systems would vary widely depending on the customer category, location and the size of the equipment. Based on the Benefit to Cost ratio criterion, the most attractive sites for installing wind PDGS for residential communities are Ras Muneef, Mafraq, Aqaba, Irbid and H5, while it doesn't seem attractive at Amman,Shoubak, Ghor Essafi, Deir Alla, Maan and H4. On the other hand, the wind on-grid PDGS is very attractive at Ras Muneef, mafraq and Aqaba for commercial buildings, less attractive at H5 and irbid, while it's not attractive at the other sites. The attraction for hybrid PDG systems is closer to those of wind systems alone. (authors).

RELIABILITY ANALYSIS OF POWER DISTRIBUTION SYSTEMS

Directory of Open Access Journals (Sweden)

Popescu V.S.

2012-04-01

Full Text Available Power distribution systems are basic parts of power systems and reliability of these systems at present is a key issue for power engineering development and requires special attention. Operation of distribution systems is accompanied by a number of factors that produce random data a large number of unplanned interruptions. Research has shown that the predominant factors that have a significant influence on the reliability of distribution systems are: weather conditions (39.7%, defects in equipment(25% and unknown random factors (20.1%. In the article is studied the influence of random behavior and are presented estimations of reliability of predominantly rural electrical distribution systems.

Optimal Operation of Radial Distribution Systems Using Extended Dynamic Programming

DEFF Research Database (Denmark)

Lopez, Juan Camilo; Vergara, Pedro P.; Lyra, Christiano

2018-01-01

An extended dynamic programming (EDP) approach is developed to optimize the ac steady-state operation of radial electrical distribution systems (EDS). Based on the optimality principle of the recursive Hamilton-Jacobi-Bellman equations, the proposed EDP approach determines the optimal operation o...... approach is illustrated using real-scale systems and comparisons with commercial programming solvers. Finally, generalizations to consider other EDS operation problems are also discussed.......An extended dynamic programming (EDP) approach is developed to optimize the ac steady-state operation of radial electrical distribution systems (EDS). Based on the optimality principle of the recursive Hamilton-Jacobi-Bellman equations, the proposed EDP approach determines the optimal operation...... of the EDS by setting the values of the controllable variables at each time period. A suitable definition for the stages of the problem makes it possible to represent the optimal ac power flow of radial EDS as a dynamic programming problem, wherein the 'curse of dimensionality' is a minor concern, since...

Variational assimilation of streamflow into operational distributed hydrologic models: effect of spatiotemporal adjustment scale

Science.gov (United States)

Lee, H.; Seo, D.-J.; Liu, Y.; Koren, V.; McKee, P.; Corby, R.

2012-01-01

State updating of distributed rainfall-runoff models via streamflow assimilation is subject to overfitting because large dimensionality of the state space of the model may render the assimilation problem seriously under-determined. To examine the issue in the context of operational hydrology, we carry out a set of real-world experiments in which streamflow data is assimilated into gridded Sacramento Soil Moisture Accounting (SAC-SMA) and kinematic-wave routing models of the US National Weather Service (NWS) Research Distributed Hydrologic Model (RDHM) with the variational data assimilation technique. Study basins include four basins in Oklahoma and five basins in Texas. To assess the sensitivity of data assimilation performance to dimensionality reduction in the control vector, we used nine different spatiotemporal adjustment scales, where state variables are adjusted in a lumped, semi-distributed, or distributed fashion and biases in precipitation and potential evaporation (PE) are adjusted hourly, 6-hourly, or kept time-invariant. For each adjustment scale, three different streamflow assimilation scenarios are explored, where streamflow observations at basin interior points, at the basin outlet, or at both interior points and the outlet are assimilated. The streamflow assimilation experiments with nine different basins show that the optimum spatiotemporal adjustment scale varies from one basin to another and may be different for streamflow analysis and prediction in all of the three streamflow assimilation scenarios. The most preferred adjustment scale for seven out of nine basins is found to be the distributed, hourly scale, despite the fact that several independent validation results at this adjustment scale indicated the occurrence of overfitting. Basins with highly correlated interior and outlet flows tend to be less sensitive to the adjustment scale and could benefit more from streamflow assimilation. In comparison to outlet flow assimilation, interior flow

Small-scale hybrid plant integrated with municipal energy supply system

International Nuclear Information System (INIS)

Bakken, B.H.; Fossum, M.; Belsnes, M.M.

2001-01-01

This paper describes a research program started in 2001 to optimize environmental impact and cost of a small-scale hybrid plant based on candidate resources, transportation technologies and conversion efficiency, including integration with existing energy distribution systems. Special attention is given to a novel hybrid energy concept fuelled by municipal solid waste. The commercial interest for the model is expected to be more pronounced in remote communities and villages, including communities subject to growing prosperity. To enable optimization of complex energy distribution systems with multiple energy sources and carriers a flexible and robust methodology must be developed. This will enable energy companies and consultants to carry out comprehensive feasibility studies prior to investment, including technological, economic and environmental aspects. Governmental and municipal bodies will be able to pursue scenario studies involving energy systems and their impact on the environment, and measure the consequences of possible regulation regimes on environmental questions. This paper describes the hybrid concept for conversion of municipal solid waste in terms of energy supply, as well as the methodology for optimizing such integrated energy systems. (author)

Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

Directory of Open Access Journals (Sweden)

Francesco Mazzarini

2014-06-01

Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

Study of Solid State Drives performance in PROOF distributed analysis system

Science.gov (United States)

Panitkin, S. Y.; Ernst, M.; Petkus, R.; Rind, O.; Wenaus, T.

2010-04-01

Solid State Drives (SSD) is a promising storage technology for High Energy Physics parallel analysis farms. Its combination of low random access time and relatively high read speed is very well suited for situations where multiple jobs concurrently access data located on the same drive. It also has lower energy consumption and higher vibration tolerance than Hard Disk Drive (HDD) which makes it an attractive choice in many applications raging from personal laptops to large analysis farms. The Parallel ROOT Facility - PROOF is a distributed analysis system which allows to exploit inherent event level parallelism of high energy physics data. PROOF is especially efficient together with distributed local storage systems like Xrootd, when data are distributed over computing nodes. In such an architecture the local disk subsystem I/O performance becomes a critical factor, especially when computing nodes use multi-core CPUs. We will discuss our experience with SSDs in PROOF environment. We will compare performance of HDD with SSD in I/O intensive analysis scenarios. In particular we will discuss PROOF system performance scaling with a number of simultaneously running analysis jobs.

The role of the input scale in parton distribution analyses

International Nuclear Information System (INIS)

Jimenez-Delgado, Pedro

2012-01-01

A first systematic study of the effects of the choice of the input scale in global determinations of parton distributions and QCD parameters is presented. It is shown that, although in principle the results should not depend on these choices, in practice a relevant dependence develops as a consequence of what is called procedural bias. This uncertainty should be considered in addition to other theoretical and experimental errors, and a practical procedure for its estimation is proposed. Possible sources of mistakes in the determination of QCD parameter from parton distribution analysis are pointed out.

Geographical ecology of the palms (Arecaceae): determinants of diversity and distributions across spatial scales

DEFF Research Database (Denmark)

Eiserhardt, Wolf L.; Svenning, J.-C.; Kissling, W. Daniel

2011-01-01

, and dispersal again at all scales. For species richness, climate and dispersal appear to be important at continental to global scales, soil at landscape and broader scales, and topography at landscape and finer scales. Some scale–predictor combinations have not been studied or deserve further attention, e......Background The palm family occurs in all tropical and sub-tropical regions of the world. Palms are of high ecological and economical importance, and display complex spatial patterns of species distributions and diversity. Scope This review summarizes empirical evidence for factors that determine...... palm species distributions, community composition and species richness such as the abiotic environment (climate, soil chemistry, hydrology and topography), the biotic environment (vegetation structure and species interactions) and dispersal. The importance of contemporary vs. historical impacts...

Dynamical scaling and crossover from algebraic to logarithmic growth in dilute systems

DEFF Research Database (Denmark)

Mouritsen, Ole G.; Shah, Peter Jivan

1989-01-01

The ordering dynamics of the two-dimensional Ising antiferromagnet with mobile vacancies and nonconserved order parameter is studied by Monte Carlo temperature-quenching experiments. The domain-size distribution function is shown to obey dynamical scaling. A crossover is found from an algebraic...... growth law for the pure system to effectively logarithmic growth behavior in the dilute system, in accordance with recent experiments on ordering kinetics in impure chemisorbed overlayers and off-stoichiometric alloys....

Pore-Scale Investigation on Stress-Dependent Characteristics of Granular Packs and Their Impact on Multiphase Fluid Distribution

Science.gov (United States)

Torrealba, V.; Karpyn, Z.; Yoon, H.; Hart, D. B.; Klise, K. A.

2013-12-01

The pore-scale dynamics that govern multiphase flow under variable stress conditions are not well understood. This lack of fundamental understanding limits our ability to quantitatively predict multiphase flow and fluid distributions in natural geologic systems. In this research, we focus on pore-scale, single and multiphase flow properties that impact displacement mechanisms and residual trapping of non-wetting phase under varying stress conditions. X-ray micro-tomography is used to image pore structures and distribution of wetting and non-wetting fluids in water-wet synthetic granular packs, under dynamic load. Micro-tomography images are also used to determine structural features such as medial axis, surface area, and pore body and throat distribution; while the corresponding transport properties are determined from Lattice-Boltzmann simulations performed on lattice replicas of the imaged specimens. Results are used to investigate how inter-granular deformation mechanisms affect fluid displacement and residual trapping at the pore-scale. This will improve our understanding of the dynamic interaction of mechanical deformation and fluid flow during enhanced oil recovery and geologic CO2 sequestration. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Interpreting Popov criteria in Lure´ systems with complex scaling stability analysis

Science.gov (United States)

Zhou, J.

2018-06-01

The paper presents a novel frequency-domain interpretation of Popov criteria for absolute stability in Lure´ systems by means of what we call complex scaling stability analysis. The complex scaling technique is developed for exponential/asymptotic stability in LTI feedback systems, which dispenses open-loop poles distribution, contour/locus orientation and prior frequency sweeping. Exploiting the technique for alternatively revealing positive realness of transfer functions, re-interpreting Popov criteria is explicated. More specifically, the suggested frequency-domain stability conditions are conformable both in scalar and multivariable cases, and can be implemented either graphically with locus plotting or numerically without; in particular, the latter is suitable as a design tool with auxiliary parameter freedom. The interpretation also reveals further frequency-domain facts about Lure´ systems. Numerical examples are included to illustrate the main results.

Wafer-scale fabrication of polymer distributed feedback lasers

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Schøler, Mikkel; Balslev, Søren

2006-01-01

The authors demonstrate wafer-scale, parallel process fabrication of distributed feedback (DFB) polymer dye lasers by two different nanoimprint techniques: By thermal nanoimprint lithography (TNIL) in polymethyl methacrylate and by combined nanoimprint and photolithography (CNP) in SU-8. In both...... techniques, a thin film of polymer, doped with rhodamine-6G laser dye, is spin coated onto a Borofloat glass buffer substrate and shaped into a planar waveguide slab with first order DFB surface corrugations forming the laser resonator. When optically pumped at 532 nm, lasing is obtained in the wavelength...... range between 576 and 607 nm, determined by the grating period. The results, where 13 laser devices are defined across a 10 cm diameter wafer substrate, demonstrate the feasibility of NIL and CNP for parallel wafer-scale fabrication of advanced nanostructured active optical polymer components...

Integrated Computing, Communication, and Distributed Control of Deregulated Electric Power Systems

Energy Technology Data Exchange (ETDEWEB)

Bajura, Richard; Feliachi, Ali

2008-09-24

Restructuring of the electricity market has affected all aspects of the power industry from generation to transmission, distribution, and consumption. Transmission circuits, in particular, are stressed often exceeding their stability limits because of the difficulty in building new transmission lines due to environmental concerns and financial risk. Deregulation has resulted in the need for tighter control strategies to maintain reliability even in the event of considerable structural changes, such as loss of a large generating unit or a transmission line, and changes in loading conditions due to the continuously varying power consumption. Our research efforts under the DOE EPSCoR Grant focused on Integrated Computing, Communication and Distributed Control of Deregulated Electric Power Systems. This research is applicable to operating and controlling modern electric energy systems. The controls developed by APERC provide for a more efficient, economical, reliable, and secure operation of these systems. Under this program, we developed distributed control algorithms suitable for large-scale geographically dispersed power systems and also economic tools to evaluate their effectiveness and impact on power markets. Progress was made in the development of distributed intelligent control agents for reliable and automated operation of integrated electric power systems. The methodologies employed combine information technology, control and communication, agent technology, and power systems engineering in the development of intelligent control agents for reliable and automated operation of integrated electric power systems. In the event of scheduled load changes or unforeseen disturbances, the power system is expected to minimize the effects and costs of disturbances and to maintain critical infrastructure operational.

Distributed optimal coordination for distributed energy resources in power systems

DEFF Research Database (Denmark)

Wu, Di; Yang, Tao; Stoorvogel, A.

2017-01-01

Driven by smart grid technologies, distributed energy resources (DERs) have been rapidly developing in recent years for improving reliability and efficiency of distribution systems. Emerging DERs require effective and efficient coordination in order to reap their potential benefits. In this paper......, we consider an optimal DER coordination problem over multiple time periods subject to constraints at both system and device levels. Fully distributed algorithms are proposed to dynamically and automatically coordinate distributed generators with multiple/single storages. With the proposed algorithms...

Real-time graphic display system for ROSA-V Large Scale Test Facility

International Nuclear Information System (INIS)

Kondo, Masaya; Anoda, Yoshinari; Osaki, Hideki; Kukita, Yutaka; Takigawa, Yoshio.

1993-11-01

A real-time graphic display system was developed for the ROSA-V Large Scale Test Facility (LSTF) experiments simulating accident management measures for prevention of severe core damage in pressurized water reactors (PWRs). The system works on an IBM workstation (Power Station RS/6000 model 560) and accommodates 512 channels out of about 2500 total measurements in the LSTF. It has three major functions: (a) displaying the coolant inventory distribution in the facility primary and secondary systems; (b) displaying the measured quantities at desired locations in the facility; and (c) displaying the time histories of measured quantities. The coolant inventory distribution is derived from differential pressure measurements along vertical sections and gamma-ray densitometer measurements for horizontal legs. The color display indicates liquid subcooling calculated from pressure and temperature at individual locations. (author)

Bayesian Estimation of the Scale Parameter of Inverse Weibull Distribution under the Asymmetric Loss Functions

Directory of Open Access Journals (Sweden)

Farhad Yahgmaei

2013-01-01

Full Text Available This paper proposes different methods of estimating the scale parameter in the inverse Weibull distribution (IWD. Specifically, the maximum likelihood estimator of the scale parameter in IWD is introduced. We then derived the Bayes estimators for the scale parameter in IWD by considering quasi, gamma, and uniform priors distributions under the square error, entropy, and precautionary loss functions. Finally, the different proposed estimators have been compared by the extensive simulation studies in corresponding the mean square errors and the evolution of risk functions.

Research in Distributed Real-Time Systems

Science.gov (United States)

Mukkamala, R.

1997-01-01

This document summarizes the progress we have made on our study of issues concerning the schedulability of real-time systems. Our study has produced several results in the scalability issues of distributed real-time systems. In particular, we have used our techniques to resolve schedulability issues in distributed systems with end-to-end requirements. During the next year (1997-98), we propose to extend the current work to address the modeling and workload characterization issues in distributed real-time systems. In particular, we propose to investigate the effect of different workload models and component models on the design and the subsequent performance of distributed real-time systems.

Innovating a system for producing and distributing hybrid oil palm seedlings to smallholder farmers in Benin

NARCIS (Netherlands)

Vissoh, Pierre V.; Tossou, Rigobert C.; Akpo, Essegbemon; Kossou, Dansou; Jiggins, Janice

2017-01-01

This article analyses the development of a system for producing and distributing hybrid oil palm seedlings to small-scale famers. The existing seed system had become so corrupted that the seedlings actually planted were largely of unimproved kinds. The article describes institutional experiments

A Distribution-class Locational Marginal Price (DLMP) Index for Enhanced Distribution Systems

Science.gov (United States)

Akinbode, Oluwaseyi Wemimo

The smart grid initiative is the impetus behind changes that are expected to culminate into an enhanced distribution system with the communication and control infrastructure to support advanced distribution system applications and resources such as distributed generation, energy storage systems, and price responsive loads. This research proposes a distribution-class analog of the transmission LMP (DLMP) as an enabler of the advanced applications of the enhanced distribution system. The DLMP is envisioned as a control signal that can incentivize distribution system resources to behave optimally in a manner that benefits economic efficiency and system reliability and that can optimally couple the transmission and the distribution systems. The DLMP is calculated from a two-stage optimization problem; a transmission system OPF and a distribution system OPF. An iterative framework that ensures accurate representation of the distribution system's price sensitive resources for the transmission system problem and vice versa is developed and its convergence problem is discussed. As part of the DLMP calculation framework, a DCOPF formulation that endogenously captures the effect of real power losses is discussed. The formulation uses piecewise linear functions to approximate losses. This thesis explores, with theoretical proofs, the breakdown of the loss approximation technique when non-positive DLMPs/LMPs occur and discusses a mixed integer linear programming formulation that corrects the breakdown. The DLMP is numerically illustrated in traditional and enhanced distribution systems and its superiority to contemporary pricing mechanisms is demonstrated using price responsive loads. Results show that the impact of the inaccuracy of contemporary pricing schemes becomes significant as flexible resources increase. At high elasticity, aggregate load consumption deviated from the optimal consumption by up to about 45 percent when using a flat or time-of-use rate. Individual load

Systems Measures of Water Distribution System Resilience

Energy Technology Data Exchange (ETDEWEB)

Klise, Katherine A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Murray, Regan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Walker, La Tonya Nicole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-01-01

Resilience is a concept that is being used increasingly to refer to the capacity of infrastructure systems to be prepared for and able to respond effectively and rapidly to hazardous events. In Section 2 of this report, drinking water hazards, resilience literature, and available resilience tools are presented. Broader definitions, attributes and methods for measuring resilience are presented in Section 3. In Section 4, quantitative systems performance measures for water distribution systems are presented. Finally, in Section 5, the performance measures and their relevance to measuring the resilience of water systems to hazards is discussed along with needed improvements to water distribution system modeling tools.

Universal scaling of the distribution of land in urban areas

Science.gov (United States)

Riascos, A. P.

2017-09-01

In this work, we explore the spatial structure of built zones and green areas in diverse western cities by analyzing the probability distribution of areas and a coefficient that characterize their respective shapes. From the analysis of diverse datasets describing land lots in urban areas, we found that the distribution of built-up areas and natural zones in cities obey inverse power laws with a similar scaling for the cities explored. On the other hand, by studying the distribution of shapes of lots in urban regions, we are able to detect global differences in the spatial structure of the distribution of land. Our findings introduce information about spatial patterns that emerge in the structure of urban settlements; this knowledge is useful for the understanding of urban growth, to improve existing models of cities, in the context of sustainability, in studies about human mobility in urban areas, among other applications.

State Electricity Regulatory Policy and Distributed Resources: Distributed Resources and Electric System Reliability

Energy Technology Data Exchange (ETDEWEB)

Cowart, R.; Harrington, C.; Moskovitz, D.; Shirley, W.; Weston, F.; Sedano, R.

2002-10-01

Designing and implementing credit-based pilot programs for distributed resources distribution is a low-cost, low-risk opportunity to find out how these resources can help defer or avoid costly electric power system (utility grid) distribution upgrades. This report describes implementation options for deaveraged distribution credits and distributed resource development zones. Developing workable programs implementing these policies can dramatically increase the deployment of distributed resources in ways that benefit distributed resource vendors, users, and distribution utilities. This report is one in the State Electricity Regulatory Policy and Distributed Resources series developed under contract to NREL (see Annual Technical Status Report of the Regulatory Assistance Project: September 2000-September 2001, NREL/SR-560-32733). Other titles in this series are: (1) Accommodating Distributed Resources in Wholesale Markets, NREL/SR-560-32497; (2) Distributed Resources and Electric System Re liability, NREL/SR-560-32498; (3) Distribution System Cost Methodologies for Distributed Generation, NREL/SR-560-32500; (4) Distribution System Cost Methodologies for Distributed Generation Appendices, NREL/SR-560-32501.

Mixed-mode distribution systems for high average power electron cyclotron heating

International Nuclear Information System (INIS)

White, T.L.; Kimrey, H.D.; Bigelow, T.S.

1984-01-01

The ELMO Bumpy Torus-Scale (EBT-S) experiment consists of 24 simple magnetic mirrors joined end-to-end to form a torus of closed magnetic field lines. In this paper, we first describe an 80% efficient mixed-mode unpolarized heating system which couples 28-GHz microwave power to the midplane of the 24 EBT-S cavities. The system consists of two radiused bends feeding a quasi-optical mixed-mode toroidal distribution manifold. Balancing power to the 24 cavities is determined by detailed computer ray tracing. A second 28-GHz electron cyclotron heating (ECH) system using a polarized grid high field launcher is described. The launcher penetrates the fundamental ECH resonant surface without a vacuum window with no observable breakdown up to 1 kW/cm 2 (source limited) with 24 kW delivered to the plasma. This system uses the same mixed-mode output as the first system but polarizes the launched power by using a grid of WR42 apertures. The efficiency of this system is 32%, but can be improved by feeding multiple launchers from a separate distribution manifold

SAFCM: A Security-Aware Feedback Control Mechanism for Distributed Real-Time Embedded Systems

DEFF Research Database (Denmark)

Ma, Yue; Jiang, Wei; Sang, Nan

2012-01-01

Distributed Real-time Embedded (DRE) systems are facing great challenges in networked, unpredictable and especially unsecured environments. In such systems, there is a strong need to enforce security on distributed computing nodes in order to guard against potential threats, while satisfying......-time systems, a multi-input multi-output feedback loop is designed and a model predictive controller is deployed based on an equation model that describes the dynamic behavior of the DRE systems. This control loop uses security level scaling to globally control the CPU utilization and security performance...... for the whole system. We propose a "security level" metric based on an evolution of cryptography algorithms used in embedded systems. Experimental results demonstrate that SAFCM not only has the excellent adaptivity compared to open-loop mechanism, but also has a better overall performance than PID control...

Automating large-scale reactor systems

International Nuclear Information System (INIS)

Kisner, R.A.

1985-01-01

This paper conveys a philosophy for developing automated large-scale control systems that behave in an integrated, intelligent, flexible manner. Methods for operating large-scale systems under varying degrees of equipment degradation are discussed, and a design approach that separates the effort into phases is suggested. 5 refs., 1 fig

Reliability Evaluation of Distribution System Considering Sequential Characteristics of Distributed Generation

Directory of Open Access Journals (Sweden)

Sheng Wanxing

2016-01-01

Full Text Available In allusion to the randomness of output power of distributed generation (DG, a reliability evaluation model based on sequential Monte Carlo simulation (SMCS for distribution system with DG is proposed. Operating states of the distribution system can be sampled by SMCS in chronological order thus the corresponding output power of DG can be generated. The proposed method has been tested on feeder F4 of IEEE-RBTS Bus 6. The results show that reliability evaluation of distribution system considering the uncertainty of output power of DG can be effectively implemented by SMCS.

Grid-connected distributed solar power systems

Science.gov (United States)

Moyle, R.; Chernoff, H.; Schweizer, T.

This paper discusses some important, though often ignored, technical and economic issues of distributed solar power systems: protection of the utility system and nonsolar customers requires suitable interfaced equipment. Purchase criteria must mirror reality; most analyses use life-cycle costing with low discount rates - most buyers use short payback periods. Distributing, installing, and marketing small, distributed solar systems is more costly than most analyses estimate. Results show that certain local conditions and uncommon purchase considerations can combine to make small, distributed solar power attractive, but lower interconnect costs (per kW), lower marketing and product distribution costs, and more favorable purchase criteria make large, centralized solar energy more attractive. Specifically, the value of dispersed solar systems to investors and utilities can be higher than $2000/kw. However, typical residential owners place a value of well under $1000 on the installed system.

Islanding Operation of Distribution System with Distributed Generations

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

The growing interest in distributed generations (DGs) due to environmental concern and various other reasons have resulted in significant penetration of DGs in many distribution system worldwide. DGs come with many benefits. One of the benefits is improved reliability by supplying load during power...

Scaling up the production and distribution of double-fortified salt in ...

International Development Research Centre (IDRC) Digital Library (Canada)

It will take to scale the manufacture and distribution of a shelf-stable salt, ... Public and private sector models, based on consumer response and policy dialogue, will be ... This project is funded under the Canadian International Food Security ...

Understanding I/O workload characteristics of a Peta-scale storage system

Energy Technology Data Exchange (ETDEWEB)

Kim, Youngjae [ORNL; Gunasekaran, Raghul [ORNL

2015-01-01

Understanding workload characteristics is critical for optimizing and improving the performance of current systems and software, and architecting new storage systems based on observed workload patterns. In this paper, we characterize the I/O workloads of scientific applications of one of the world s fastest high performance computing (HPC) storage cluster, Spider, at the Oak Ridge Leadership Computing Facility (OLCF). OLCF flagship petascale simulation platform, Titan, and other large HPC clusters, in total over 250 thousands compute cores, depend on Spider for their I/O needs. We characterize the system utilization, the demands of reads and writes, idle time, storage space utilization, and the distribution of read requests to write requests for the Peta-scale Storage Systems. From this study, we develop synthesized workloads, and we show that the read and write I/O bandwidth usage as well as the inter-arrival time of requests can be modeled as a Pareto distribution. We also study the I/O load imbalance problems using I/O performance data collected from the Spider storage system.

Magnetospheric MultiScale (MMS) System Manager

Science.gov (United States)

Schiff, Conrad; Maher, Francis Alfred; Henely, Sean Philip; Rand, David

2014-01-01

The Magnetospheric MultiScale (MMS) mission is an ambitious NASA space science mission in which 4 spacecraft are flown in tight formation about a highly elliptical orbit. Each spacecraft has multiple instruments that measure particle and field compositions in the Earths magnetosphere. By controlling the members relative motion, MMS can distinguish temporal and spatial fluctuations in a way that a single spacecraft cannot.To achieve this control, 2 sets of four maneuvers, distributed evenly across the spacecraft must be performed approximately every 14 days. Performing a single maneuver on an individual spacecraft is usually labor intensive and the complexity becomes clearly increases with four. As a result, the MMS flight dynamics team turned to the System Manager to put the routine or error-prone under machine control freeing the analysts for activities that require human judgment.The System Manager is an expert system that is capable of handling operations activities associated with performing MMS maneuvers. As an expert system, it can work off a known schedule, launching jobs based on a one-time occurrence or on a set reoccurring schedule. It is also able to detect situational changes and use event-driven programming to change schedules, adapt activities, or call for help.

Scaling CMS data transfer system for LHC start-up

International Nuclear Information System (INIS)

Tuura, L; Bockelman, B; Bonacorsi, D; Egeland, R; Feichtinger, D; Metson, S; Rehn, J

2008-01-01

The CMS experiment will need to sustain uninterrupted high reliability, high throughput and very diverse data transfer activities as the LHC operations start. PhEDEx, the CMS data transfer system, will be responsible for the full range of the transfer needs of the experiment. Covering the entire spectrum is a demanding task: from the critical high-throughput transfers between CERN and the Tier-1 centres, to high-scale production transfers among the Tier-1 and Tier-2 centres, to managing the 24/7 transfers among all the 170 institutions in CMS and to providing straightforward access to handful of files to individual physicists. In order to produce the system with confirmed capability to meet the objectives, the PhEDEx data transfer system has undergone rigourous development and numerous demanding scale tests. We have sustained production transfers exceeding 1 PB/month for several months and have demonstrated core system capacity several orders of magnitude above expected LHC levels. We describe the level of scalability reached, and how we got there, with focus on the main insights into developing a robust, lock-free and scalable distributed database application, the validation stress test methods we have used, and the development and testing tools we found practically useful

Scale effect challenges in urban hydrology highlighted with a Fully Distributed Model and High-resolution rainfall data

Science.gov (United States)

Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel; Bompard, Philippe; Ten Veldhuis, Marie-Claire

2017-04-01

Nowadays, there is a growing interest on small-scale rainfall information, provided by weather radars, to be used in urban water management and decision-making. Therefore, an increasing interest is in parallel devoted to the development of fully distributed and grid-based models following the increase of computation capabilities, the availability of high-resolution GIS information needed for such models implementation. However, the choice of an appropriate implementation scale to integrate the catchment heterogeneity and the whole measured rainfall variability provided by High-resolution radar technologies still issues. This work proposes a two steps investigation of scale effects in urban hydrology and its effects on modeling works. In the first step fractal tools are used to highlight the scale dependency observed within distributed data used to describe the catchment heterogeneity, both the structure of the sewer network and the distribution of impervious areas are analyzed. Then an intensive multi-scale modeling work is carried out to understand scaling effects on hydrological model performance. Investigations were conducted using a fully distributed and physically based model, Multi-Hydro, developed at Ecole des Ponts ParisTech. The model was implemented at 17 spatial resolutions ranging from 100 m to 5 m and modeling investigations were performed using both rain gauge rainfall information as well as high resolution X band radar data in order to assess the sensitivity of the model to small scale rainfall variability. Results coming out from this work demonstrate scale effect challenges in urban hydrology modeling. In fact, fractal concept highlights the scale dependency observed within distributed data used to implement hydrological models. Patterns of geophysical data change when we change the observation pixel size. The multi-scale modeling investigation performed with Multi-Hydro model at 17 spatial resolutions confirms scaling effect on hydrological model

Advanced Distribution Management System

OpenAIRE

Avazov, Artur; Sobinova, Lubov Anatolievna

2016-01-01

This article describes the advisability of using advanced distribution management systems in the electricity distribution networks area and considers premises of implementing ADMS within the Smart Grid era. Also, it gives the big picture of ADMS and discusses the ADMS advantages and functionalities.

Advanced Distribution Management System

Science.gov (United States)

Avazov, Artur R.; Sobinova, Liubov A.

2016-02-01

This article describes the advisability of using advanced distribution management systems in the electricity distribution networks area and considers premises of implementing ADMS within the Smart Grid era. Also, it gives the big picture of ADMS and discusses the ADMS advantages and functionalities.

The accumulation of radioactive contaminants in drinking water distribution systems.

Science.gov (United States)

Lytle, Darren A; Sorg, Thomas; Wang, Lili; Chen, Abe

2014-03-01

The accumulation of trace contaminants in drinking water distribution system sediment and scales has been documented, raising concerns that the subsequent release of the contaminants back to the water is a potential human exposure pathway. Radioactive contaminants are of concern because of their known health effects and because of their persistence within associated distribution system materials. The objective of this work was to measure the amount of a number of radioactive contaminants (radium, thorium, and uranium isotopes, and gross alpha and beta activity) in distribution solids collected from water systems in four states (Wisconsin, Illinois, Minnesota, and Texas). The water utilities chosen had measurable levels of radium in their source waters. In addition, 19 other elements in the solids were quantified. Water systems provided solids primarily collected during routine fire hydrant flushing. Iron was the dominant element in nearly all of the solids and was followed by calcium, phosphorus, magnesium, manganese, silicon, aluminum and barium in descending order. Gross alpha and beta radiation averaged 255 and 181 pCi/g, and were as high as 1602 and 1169 pCi/g, respectively. Total radium, thorium and uranium averaged 143, 40 and 6.4 pCi/g, respectively. Radium-226 and -228 averaged 74 and 69 pCi/g, and were as high as 250 and 351 pCi/g, respectively. Published by Elsevier Ltd.

Control and Operation of Islanded Distribution System

DEFF Research Database (Denmark)

Mahat, Pukar

deviation and real power shift. When a distribution system, with all its generators operating at maximum power, is islanded, the frequency will go down if the total load is more than the total generation. An under-frequency load shedding procedure for islanded distribution systems with DG unit(s) based...... states. Short circuit power also changes when some of the generators in the distribution system are disconnected. This may result in elongation of fault clearing time and hence disconnection of equipments (including generators) in the distribution system or unnecessary operation of protective devices...... operational challenges. But, on the other hand, it has also opened up some opportunities. One opportunity/challenge is an islanded operation of a distribution system with DG unit(s). Islanding is a situation in which a distribution system becomes electrically isolated from the remainder of the power system...

Flexible distribution systems through the application of multi back-to-back converters. Concept, implementation and experimental verification

Energy Technology Data Exchange (ETDEWEB)

De Graaff, R A.A.

2010-05-26

The objective of the research project is to investigate the use of a multi back-to-back converter to support the transition to active distribution networks. The investigation must explicitly not focus on finding the optimal power electronics topology, but rather on defining the role that such a device can play in a power distribution system and on the proof of principle. The possible tasks of this device are to actively control power flow and to maintain power quality and stability, both during normal operation and during fault conditions in medium voltage networks with distributed generation. The combination of this versatile converter system and the control and protection systems that define its functionality are in this thesis denoted as the Intelligent Node (IN). Research questions are: (1) Which are the main benefits of multi back-to-back converter devices in distribution systems?; (2) How and under which conditions can these benefits be achieved? What controls should be adopted?; (3) Which are the specific aspects that distinguish the application of the multi back-to-back devices in distribution systems from similar applications in transmission systems?; (4) Can this be demonstrated on a laboratory-scale set-up?Chapter 2 Distribution systems The relevant aspects of distribution systems are discussed. This includes power quality considerations, redundancy aspects, and voltage control methods. Chapter 3 (FACTS in distribution systems) describes power flow control principles. Also an overview is given of the state-of-the-art of power electronic applications for power flow control in electrical power systems. Chapter 4 (Functional concept of the Intelligent Node) gives the proposed functional concept for the application of a multi back-to-back converter device as IN (Intelligent Node). The applications are developed on a functional level, with the device at a black-box level. To satisfy the resulting requirements several technology options are analyzed, ending

Water Treatment Technology - Distribution Systems.

Science.gov (United States)

Ross-Harrington, Melinda; Kincaid, G. David

One of twelve water treatment technology units, this student manual on distribution systems provides instructional materials for six competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: types of pipe for distribution systems, types…

Integrating photovoltaics into utility distribution systems

International Nuclear Information System (INIS)

Zaininger, H.W.; Barnes, P.R.

1995-01-01

Electric utility distribution system impacts associated with the integration of distributed photovoltaic (PV) energy sources vary from site to site and utility to utility. The objective of this paper is to examine several utility- and site-specific conditions which may affect economic viability of distributed PV applications to utility systems. Assessment methodology compatible with technical and economic assessment techniques employed by utility engineers and planners is employed to determine PV benefits for seven different utility systems. The seven case studies are performed using utility system characteristics and assumptions obtained from appropriate utility personnel. The resulting site-specific distributed PV benefits increase nonsite-specific generation system benefits available to central station PV plants as much as 46%, for one utility located in the Southwest

Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks

Directory of Open Access Journals (Sweden)

Guangwen Fan

2015-09-01

Full Text Available Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications.

Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks.

Science.gov (United States)

Fan, Guangwen; Shen, Yu; Hao, Xiaowei; Yuan, Zongming; Zhou, Zhi

2015-09-18

Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG) storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications.

Scaling-Up the Functional Diagnostic Systems

International Nuclear Information System (INIS)

Mohamed, A.H.

2008-01-01

Functional diagnostic systems received a lot of attention in the last decade. They have proven their powerful for diagnosis the new faults of some complex systems. But, they still have some complexity in both the representation and reasoning about the large-scale systems. This paper introduces a new functional diagnostic system that can divide its small functions into main and auxiliary ones. This process enables the diagnostic system to scale -up the representation of the tested system and simplify the diagnostic mechanism tasks. Thus, it can improve both the representation and reasoning complexity. Also,it can decrease the required analysis, cost, and time. Proposed system can be applied for a wide area of the large-scale systems. It has been proven its acceptance to be applied practically for the Complex real-time systems

An adaptive scaling and biasing scheme for OFDM-based visible light communication systems.

Science.gov (United States)

Wang, Zhaocheng; Wang, Qi; Chen, Sheng; Hanzo, Lajos

2014-05-19

Orthogonal frequency-division multiplexing (OFDM) has been widely used in visible light communication systems to achieve high-rate data transmission. Due to the nonlinear transfer characteristics of light emitting diodes (LEDs) and owing the high peak-to-average-power ratio of OFDM signals, the transmitted signal has to be scaled and biased before modulating the LEDs. In this contribution, an adaptive scaling and biasing scheme is proposed for OFDM-based visible light communication systems, which fully exploits the dynamic range of the LEDs and improves the achievable system performance. Specifically, the proposed scheme calculates near-optimal scaling and biasing factors for each specific OFDM symbol according to the distribution of the signals, which strikes an attractive trade-off between the effective signal power and the clipping-distortion power. Our simulation results demonstrate that the proposed scheme significantly improves the performance without changing the LED's emitted power, while maintaining the same receiver structure.

Planning and Optimization Methods for Active Distribution Systems

DEFF Research Database (Denmark)

Abbey, Chad; Baitch, Alex; Bak-Jensen, Birgitte

distribution planning. Active distribution networks (ADNs) have systems in place to control a combination of distributed energy resources (DERs), defined as generators, loads and storage. With these systems in place, the AND becomes an Active Distribution System (ADS). Distribution system operators (DSOs) have...

Optimization of large-scale heterogeneous system-of-systems models.

Energy Technology Data Exchange (ETDEWEB)

Parekh, Ojas; Watson, Jean-Paul; Phillips, Cynthia Ann; Siirola, John; Swiler, Laura Painton; Hough, Patricia Diane (Sandia National Laboratories, Livermore, CA); Lee, Herbert K. H. (University of California, Santa Cruz, Santa Cruz, CA); Hart, William Eugene; Gray, Genetha Anne (Sandia National Laboratories, Livermore, CA); Woodruff, David L. (University of California, Davis, Davis, CA)

2012-01-01

Decision makers increasingly rely on large-scale computational models to simulate and analyze complex man-made systems. For example, computational models of national infrastructures are being used to inform government policy, assess economic and national security risks, evaluate infrastructure interdependencies, and plan for the growth and evolution of infrastructure capabilities. A major challenge for decision makers is the analysis of national-scale models that are composed of interacting systems: effective integration of system models is difficult, there are many parameters to analyze in these systems, and fundamental modeling uncertainties complicate analysis. This project is developing optimization methods to effectively represent and analyze large-scale heterogeneous system of systems (HSoS) models, which have emerged as a promising approach for describing such complex man-made systems. These optimization methods enable decision makers to predict future system behavior, manage system risk, assess tradeoffs between system criteria, and identify critical modeling uncertainties.

A Quality-Centric Data Model for Distributed Stream Management Systems

OpenAIRE

Pietzuch, P; Fiscato, M; Vu, QH

2009-01-01

21.10.14 KB Ok to add published version to spiral. It is challenging for large-scale stream management systems to return always perfect results when processing data streams originating from distributed sources. Data sources and intermediate processing nodes may fail during the lifetime of a stream query. In addition, individual nodes may become overloaded due to processing demands. In practice, users have to accept incomplete or inaccurate query results because of failure or overload. In t...

Large Scale Beam-beam Simulations for the CERN LHC using Distributed Computing

CERN Document Server

Herr, Werner; McIntosh, E; Schmidt, F

2006-01-01

We report on a large scale simulation of beam-beam effects for the CERN Large Hadron Collider (LHC). The stability of particles which experience head-on and long-range beam-beam effects was investigated for different optical configurations and machine imperfections. To cover the interesting parameter space required computing resources not available at CERN. The necessary resources were available in the LHC@home project, based on the BOINC platform. At present, this project makes more than 60000 hosts available for distributed computing. We shall discuss our experience using this system during a simulation campaign of more than six months and describe the tools and procedures necessary to ensure consistent results. The results from this extended study are presented and future plans are discussed.

Distributed and decentralized state estimation in gas networks as distributed parameter systems.

Science.gov (United States)

Ahmadian Behrooz, Hesam; Boozarjomehry, R Bozorgmehry

2015-09-01

In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline networks. In the construction of local models, due to the existence of common states and interconnections among the subsystems, the assimilation and prediction steps of the Kalman filter are modified to take the overlapping and external states into account. However, dynamic Riccati equation for each subsystem is constructed based on the local model, which introduces a maximum error of 5% in the estimated standard deviation of the states in the benchmarks studied in this paper. The performance of the proposed methodology has been shown based on the comparison of its accuracy and computational demands against their counterparts in centralized Kalman filter for two viable benchmarks. In a real life network, it is shown that while the accuracy is not significantly decreased, the real-time factor of the state estimation is increased by a factor of 10. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Local, distributed topology control for large-scale wireless ad-hoc networks

NARCIS (Netherlands)

Nieberg, T.; Hurink, Johann L.

In this document, topology control of a large-scale, wireless network by a distributed algorithm that uses only locally available information is presented. Topology control algorithms adjust the transmission power of wireless nodes to create a desired topology. The algorithm, named local power

Coordination control of distributed systems

CERN Document Server

Villa, Tiziano

2015-01-01

This book describes how control of distributed systems can be advanced by an integration of control, communication, and computation. The global control objectives are met by judicious combinations of local and nonlocal observations taking advantage of various forms of communication exchanges between distributed controllers. Control architectures are considered according to  increasing degrees of cooperation of local controllers:  fully distributed or decentralized control,  control with communication between controllers,  coordination control, and multilevel control.  The book covers also topics bridging computer science, communication, and control, like communication for control of networks, average consensus for distributed systems, and modeling and verification of discrete and of hybrid systems. Examples and case studies are introduced in the first part of the text and developed throughout the book. They include: control of underwater vehicles, automated-guided vehicles on a container terminal, contro...

Fuzzy-driven energy storage system for mitigating voltage unbalance factor on distribution network with photovoltaic system

Science.gov (United States)

Wong, Jianhui; Lim, Yun Seng; Morris, Stella; Morris, Ezra; Chua, Kein Huat

2017-04-01

The amount of small-scaled renewable energy sources is anticipated to increase on the low-voltage distribution networks for the improvement of energy efficiency and reduction of greenhouse gas emission. The growth of the PV systems on the low-voltage distribution networks can create voltage unbalance, voltage rise, and reverse-power flow. Usually these issues happen with little fluctuation. However, it tends to fluctuate severely as Malaysia is a region with low clear sky index. A large amount of clouds often passes over the country, hence making the solar irradiance to be highly scattered. Therefore, the PV power output fluctuates substantially. These issues can lead to the malfunction of the electronic based equipment, reduction in the network efficiency and improper operation of the power protection system. At the current practice, the amount of PV system installed on the distribution network is constraint by the utility company. As a result, this can limit the reduction of carbon footprint. Therefore, energy storage system is proposed as a solution for these power quality issues. To ensure an effective operation of the distribution network with PV system, a fuzzy control system is developed and implemented to govern the operation of an energy storage system. The fuzzy driven energy storage system is able to mitigate the fluctuating voltage rise and voltage unbalance on the electrical grid by actively manipulates the flow of real power between the grid and the batteries. To verify the effectiveness of the proposed fuzzy driven energy storage system, an experimental network integrated with 7.2kWp PV system was setup. Several case studies are performed to evaluate the response of the proposed solution to mitigate voltage rises, voltage unbalance and reduce the amount of reverse power flow under highly intermittent PV power output.

Software challenges in extreme scale systems

International Nuclear Information System (INIS)

Sarkar, Vivek; Harrod, William; Snavely, Allan E

2009-01-01

Computer systems anticipated in the 2015 - 2020 timeframe are referred to as Extreme Scale because they will be built using massive multi-core processors with 100's of cores per chip. The largest capability Extreme Scale system is expected to deliver Exascale performance of the order of 10 18 operations per second. These systems pose new critical challenges for software in the areas of concurrency, energy efficiency and resiliency. In this paper, we discuss the implications of the concurrency and energy efficiency challenges on future software for Extreme Scale Systems. From an application viewpoint, the concurrency and energy challenges boil down to the ability to express and manage parallelism and locality by exploring a range of strong scaling and new-era weak scaling techniques. For expressing parallelism and locality, the key challenges are the ability to expose all of the intrinsic parallelism and locality in a programming model, while ensuring that this expression of parallelism and locality is portable across a range of systems. For managing parallelism and locality, the OS-related challenges include parallel scalability, spatial partitioning of OS and application functionality, direct hardware access for inter-processor communication, and asynchronous rather than interrupt-driven events, which are accompanied by runtime system challenges for scheduling, synchronization, memory management, communication, performance monitoring, and power management. We conclude by discussing the importance of software-hardware co-design in addressing the fundamental challenges for application enablement on Extreme Scale systems.

Why Do Electricity Policy and Competitive Markets Fail to Use Advanced PV Systems to Improve Distribution Power Quality?

Directory of Open Access Journals (Sweden)

Mark P. McHenry

2016-01-01

Full Text Available The increasing pressure for network operators to meet distribution network power quality standards with increasing peak loads, renewable energy targets, and advances in automated distributed power electronics and communications is forcing policy-makers to understand new means to distribute costs and benefits within electricity markets. Discussions surrounding how distributed generation (DG exhibits active voltage regulation and power factor/reactive power control and other power quality capabilities are complicated by uncertainties of baseline local distribution network power quality and to whom and how costs and benefits of improved electricity infrastructure will be allocated. DG providing ancillary services that dynamically respond to the network characteristics could lead to major network improvements. With proper market structures renewable energy systems could greatly improve power quality on distribution systems with nearly no additional cost to the grid operators. Renewable DG does have variability challenges, though this issue can be overcome with energy storage, forecasting, and advanced inverter functionality. This paper presents real data from a large-scale grid-connected PV array with large-scale storage and explores effective mitigation measures for PV system variability. We discuss useful inverter technical knowledge for policy-makers to mitigate ongoing inflation of electricity network tariff components by new DG interconnection requirements or electricity markets which value power quality and control.

Distribution Patterns of the Freshwater Oligochaete Limnodrilus hoffmeisteri Influenced by Environmental Factors in Streams on a Korean Nationwide Scale

Directory of Open Access Journals (Sweden)

Hyejin Kang

2017-11-01

Full Text Available Aquatic oligochaetes are very common in streams, and are used as biological assessment indicators as well as in the biological management of organic-enriched systems. In this study, we analyzed the effects of environmental factors influencing the distribution of aquatic oligochaetes Limnodrilus hoffmeisteri in streams. We used 13 environmental factors in three categories (i.e., geography, hydrology, and physicochemistry. Data on the distribution of oligochaetes and environmental factors were obtained from 1159 sampling sites throughout Korea on a nationwide scale. Hierarchical cluster analysis (HCA and nonmetric multidimensional scaling (NMDS were performed to analyze the relationships between the occurrence of aquatic oligochaetes and environmental factors. A random forest model was used to evaluate the relative importance of the environmental factors affecting the distribution of oligochaetes. HCA classified sampling sites into four groups according to differences in environmental factors, and NMDS ordination reflected the differences of environmental factors, in particular, water depth, velocity, and altitude, among the four groups defined in the HCA. Furthermore, using a random forest model, turbidity and water velocity were evaluated as highly important factors influencing the distribution of L. hoffmeisteri.

Advanced Distribution Management System

Directory of Open Access Journals (Sweden)

Avazov Artur R.

2016-01-01

Full Text Available This article describes the advisability of using advanced distribution management systems in the electricity distribution networks area and considers premises of implementing ADMS within the Smart Grid era. Also, it gives the big picture of ADMS and discusses the ADMS advantages and functionalities.

Systems of Systems: Scaling Up the Development Process

National Research Council Canada - National Science Library

Humphrey, Watts

2006-01-01

... of massive systems into system-of-systems structures Section 3 points out how large-scale systems development efforts have typically failed because of project-management and not technical problems...

Optimizing electrical distribution systems

International Nuclear Information System (INIS)

Scott, W.G.

1990-01-01

Electrical utility distribution systems are in the middle of an unprecedented technological revolution in planning, design, maintenance and operation. The prime movers of the revolution are the major economic shifts that affect decision making. The major economic influence on the revolution is the cost of losses (technical and nontechnical). The vehicle of the revolution is the computer, which enables decision makers to examine alternatives in greater depth and detail than their predecessors could. The more important elements of the technological revolution are: system planning, computers, load forecasting, analytical systems (primary systems, transformers and secondary systems), system losses and coming technology. The paper is directed towards the rather unique problems encountered by engineers of utilities in developing countries - problems that are being solved through high technology, such as the recent World Bank-financed engineering computer system for Sri Lanka. This system includes a DEC computer, digitizer, plotter and engineering software to model the distribution system via a digitizer, analyse the system and plot single-line diagrams. (author). 1 ref., 4 tabs., 6 figs

Information Power Grid: Distributed High-Performance Computing and Large-Scale Data Management for Science and Engineering

Science.gov (United States)

Johnston, William E.; Gannon, Dennis; Nitzberg, Bill

2000-01-01

We use the term "Grid" to refer to distributed, high performance computing and data handling infrastructure that incorporates geographically and organizationally dispersed, heterogeneous resources that are persistent and supported. This infrastructure includes: (1) Tools for constructing collaborative, application oriented Problem Solving Environments / Frameworks (the primary user interfaces for Grids); (2) Programming environments, tools, and services providing various approaches for building applications that use aggregated computing and storage resources, and federated data sources; (3) Comprehensive and consistent set of location independent tools and services for accessing and managing dynamic collections of widely distributed resources: heterogeneous computing systems, storage systems, real-time data sources and instruments, human collaborators, and communications systems; (4) Operational infrastructure including management tools for distributed systems and distributed resources, user services, accounting and auditing, strong and location independent user authentication and authorization, and overall system security services The vision for NASA's Information Power Grid - a computing and data Grid - is that it will provide significant new capabilities to scientists and engineers by facilitating routine construction of information based problem solving environments / frameworks. Such Grids will knit together widely distributed computing, data, instrument, and human resources into just-in-time systems that can address complex and large-scale computing and data analysis problems. Examples of these problems include: (1) Coupled, multidisciplinary simulations too large for single systems (e.g., multi-component NPSS turbomachine simulation); (2) Use of widely distributed, federated data archives (e.g., simultaneous access to metrological, topological, aircraft performance, and flight path scheduling databases supporting a National Air Space Simulation systems}; (3

Reliability assessment of distribution power systems including distributed generations

International Nuclear Information System (INIS)

Megdiche, M.

2004-12-01

Nowadays, power systems have reached a good level of reliability. Nevertheless, considering the modifications induced by the connections of small independent producers to distribution networks, there's a need to assess the reliability of these new systems. Distribution networks present several functional characteristics, highlighted by the qualitative study of the failures, as dispersed loads at several places, variable topology and some electrotechnical phenomena which must be taken into account to model the events that can occur. The adopted reliability calculations method is Monte Carlo simulations, the probabilistic method most powerful and most flexible to model complex operating of the distribution system. We devoted a first part on the case of a 20 kV feeder to which a cogeneration unit is connected. The method was applied to a software of stochastic Petri nets simulations. Then a second part related to the study of a low voltage power system supplied by dispersed generations. Here, the complexity of the events required to code the method in an environment of programming allowing the use of power system calculations (load flow, short-circuit, load shedding, management of units powers) in order to analyse the system state for each new event. (author)

Network-scale spatial and temporal variation in Chinook salmon (Oncorhynchus tshawytscha) redd distributions: patterns inferred from spatially continuous replicate surveys

Science.gov (United States)

Daniel J. Isaak; Russell F. Thurow

2006-01-01

Spatially continuous sampling designs, when temporally replicated, provide analytical flexibility and are unmatched in their ability to provide a dynamic system view. We have compiled such a data set by georeferencing the network-scale distribution of Chinook salmon (Oncorhynchus tshawytscha) redds across a large wilderness basin (7330 km2) in...

Modeling complexity in engineered infrastructure system: Water distribution network as an example

Science.gov (United States)

Zeng, Fang; Li, Xiang; Li, Ke

2017-02-01

The complex topology and adaptive behavior of infrastructure systems are driven by both self-organization of the demand and rigid engineering solutions. Therefore, engineering complex systems requires a method balancing holism and reductionism. To model the growth of water distribution networks, a complex network model was developed following the combination of local optimization rules and engineering considerations. The demand node generation is dynamic and follows the scaling law of urban growth. The proposed model can generate a water distribution network (WDN) similar to reported real-world WDNs on some structural properties. Comparison with different modeling approaches indicates that a realistic demand node distribution and co-evolvement of demand node and network are important for the simulation of real complex networks. The simulation results indicate that the efficiency of water distribution networks is exponentially affected by the urban growth pattern. On the contrary, the improvement of efficiency by engineering optimization is limited and relatively insignificant. The redundancy and robustness, on another aspect, can be significantly improved through engineering methods.

Energy efficient distributed computing systems

CERN Document Server

Lee, Young-Choon

2012-01-01

The energy consumption issue in distributed computing systems raises various monetary, environmental and system performance concerns. Electricity consumption in the US doubled from 2000 to 2005.  From a financial and environmental standpoint, reducing the consumption of electricity is important, yet these reforms must not lead to performance degradation of the computing systems.  These contradicting constraints create a suite of complex problems that need to be resolved in order to lead to 'greener' distributed computing systems.  This book brings together a group of outsta

Bluetooth-based distributed measurement system

International Nuclear Information System (INIS)

Tang Baoping; Chen Zhuo; Wei Yuguo; Qin Xiaofeng

2007-01-01

A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit

Bluetooth-based distributed measurement system

Science.gov (United States)

Tang, Baoping; Chen, Zhuo; Wei, Yuguo; Qin, Xiaofeng

2007-07-01

A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit.

Bluetooth-based distributed measurement system

Energy Technology Data Exchange (ETDEWEB)

Tang Baoping; Chen Zhuo; Wei Yuguo; Qin Xiaofeng [Department of Mechatronics, College of Mechanical Engineering, Chongqing University, Chongqing, 400030 (China)

2007-07-15

A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit.

Automatic management software for large-scale cluster system

International Nuclear Information System (INIS)

Weng Yunjian; Chinese Academy of Sciences, Beijing; Sun Gongxing

2007-01-01

At present, the large-scale cluster system faces to the difficult management. For example the manager has large work load. It needs to cost much time on the management and the maintenance of large-scale cluster system. The nodes in large-scale cluster system are very easy to be chaotic. Thousands of nodes are put in big rooms so that some managers are very easy to make the confusion with machines. How do effectively carry on accurate management under the large-scale cluster system? The article introduces ELFms in the large-scale cluster system. Furthermore, it is proposed to realize the large-scale cluster system automatic management. (authors)

Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

NARCIS (Netherlands)

Rietkerk, M.G.; Ouedraogo, T.; Kumar, L.; Sanou, S.; Langevelde, F. van; Kiema, A.; Koppel, J. van de; Andel, J. van; Hearne, J.; Skidmore, A.K.; Ridder, N. de; Stroosnijder, L.; Prins, H.H.T.

2002-01-01

We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

Experiment Dashboard for Monitoring of the LHC Distributed Computing Systems

International Nuclear Information System (INIS)

Andreeva, J; Campos, M Devesas; Cros, J Tarragon; Gaidioz, B; Karavakis, E; Kokoszkiewicz, L; Lanciotti, E; Maier, G; Ollivier, W; Nowotka, M; Rocha, R; Sadykov, T; Saiz, P; Sargsyan, L; Sidorova, I; Tuckett, D

2011-01-01

LHC experiments are currently taking collisions data. A distributed computing model chosen by the four main LHC experiments allows physicists to benefit from resources spread all over the world. The distributed model and the scale of LHC computing activities increase the level of complexity of middleware, and also the chances of possible failures or inefficiencies in involved components. In order to ensure the required performance and functionality of the LHC computing system, monitoring the status of the distributed sites and services as well as monitoring LHC computing activities are among the key factors. Over the last years, the Experiment Dashboard team has been working on a number of applications that facilitate the monitoring of different activities: including following up jobs, transfers, and also site and service availabilities. This presentation describes Experiment Dashboard applications used by the LHC experiments and experience gained during the first months of data taking.

Distribution network strengthens sales systems

International Nuclear Information System (INIS)

Janoska, J.

2003-01-01

Liberalisation of the electricity market pushes Slovak distribution companies to upgrade their sale technologies. The first one to invest into a complex electronic sales system will be Stredoslovenska energetika, a.s., Zilina. The system worth 200 million Sk (4,83 million Euro) will be supplied by Polish software company Winuel. The company should also supply a software that would allow forecasting and planning of sales. The system should be fully operational by 2006. TREND has not managed to obtain information regarding plans Zapadoslovenska energetika - the largest and most active distribution company - might have in this area. In eastern Slovakia distribution company Vychodoslovenska energetika, a.s., Kosice has also started addressing this issue. (Author)

Evolution of the ATLAS distributed computing system during the LHC long shutdown

Science.gov (United States)

Campana, S.; Atlas Collaboration

2014-06-01

The ATLAS Distributed Computing project (ADC) was established in 2007 to develop and operate a framework, following the ATLAS computing model, to enable data storage, processing and bookkeeping on top of the Worldwide LHC Computing Grid (WLCG) distributed infrastructure. ADC development has always been driven by operations and this contributed to its success. The system has fulfilled the demanding requirements of ATLAS, daily consolidating worldwide up to 1 PB of data and running more than 1.5 million payloads distributed globally, supporting almost one thousand concurrent distributed analysis users. Comprehensive automation and monitoring minimized the operational manpower required. The flexibility of the system to adjust to operational needs has been important to the success of the ATLAS physics program. The LHC shutdown in 2013-2015 affords an opportunity to improve the system in light of operational experience and scale it to cope with the demanding requirements of 2015 and beyond, most notably a much higher trigger rate and event pileup. We will describe the evolution of the ADC software foreseen during this period. This includes consolidating the existing Production and Distributed Analysis framework (PanDA) and ATLAS Grid Information System (AGIS), together with the development and commissioning of next generation systems for distributed data management (DDM/Rucio) and production (Prodsys-2). We will explain how new technologies such as Cloud Computing and NoSQL databases, which ATLAS investigated as R&D projects in past years, will be integrated in production. Finally, we will describe more fundamental developments such as breaking job-to-data locality by exploiting storage federations and caches, and event level (rather than file or dataset level) workload engines.

Evolution of the ATLAS distributed computing system during the LHC long shutdown

International Nuclear Information System (INIS)

Campana, S

2014-01-01

The ATLAS Distributed Computing project (ADC) was established in 2007 to develop and operate a framework, following the ATLAS computing model, to enable data storage, processing and bookkeeping on top of the Worldwide LHC Computing Grid (WLCG) distributed infrastructure. ADC development has always been driven by operations and this contributed to its success. The system has fulfilled the demanding requirements of ATLAS, daily consolidating worldwide up to 1 PB of data and running more than 1.5 million payloads distributed globally, supporting almost one thousand concurrent distributed analysis users. Comprehensive automation and monitoring minimized the operational manpower required. The flexibility of the system to adjust to operational needs has been important to the success of the ATLAS physics program. The LHC shutdown in 2013-2015 affords an opportunity to improve the system in light of operational experience and scale it to cope with the demanding requirements of 2015 and beyond, most notably a much higher trigger rate and event pileup. We will describe the evolution of the ADC software foreseen during this period. This includes consolidating the existing Production and Distributed Analysis framework (PanDA) and ATLAS Grid Information System (AGIS), together with the development and commissioning of next generation systems for distributed data management (DDM/Rucio) and production (Prodsys-2). We will explain how new technologies such as Cloud Computing and NoSQL databases, which ATLAS investigated as R and D projects in past years, will be integrated in production. Finally, we will describe more fundamental developments such as breaking job-to-data locality by exploiting storage federations and caches, and event level (rather than file or dataset level) workload engines.

Scaling and extrapolation of hydrogen distribution experiments

International Nuclear Information System (INIS)

Karwat, H.

1986-01-01

The containment plays an important role in predicting the residual risk to the environment under severe accident conditions. Risk analyses show that massive fission product release from the reactor fuel can occur only if during a loss of coolant the core is severely damaged and a containment failure is anticipated. Large amounts of hydrogen inevitably, are formed during the core degradation and will be released into the containment. More combustible gases are produced later when the coremelt will contact the containment concrete. Thus a potential for an early containment failure exists if a massive hydrogen deflagration cannot be excluded. A more remote cause for early containment failure may be an energetic steam explosion which requires a number of independent conditions when the molten core material contacts residual coolant water. The prediction of the containment loads caused by a hydrogen combustion is dependent on the prediction of the combustion mode. In the paper an attempt is made to identify on basis of a dimensional analysis such areas for which particular care must be exercised when scale experimental evidence is interpreted and extrapolated with the aid of a computer code or a system of computer codes. The study is restricted to fluid dynamic phenomena of the gas distribution process within the containment atmosphere. The gas sources and the mechanical response of containment structures are considered as given boundary conditions under which the containment is to be analyzed

Geographic asymmetries of the Viking auroral distribution: Implications for ionospheric coordinate systems

International Nuclear Information System (INIS)

Hearn, D.J.; Elphinstone, R.D.; Murphree, J.S.; Cogger, L.L.

1993-01-01

Viking images of the auroral distribution have been used to investigate the relevance of various ionospheric coordinate systems. An important aspect of the large-scale auroral shape is its dependence on the asymmetries of the Earth's internal field. Model predictions of where the aurora occurs, using the equatorial plane's volume current density, agree with observations and imply that the internal field plays a more important role that generally believed. Historically, the belief that the internal field has only small effects seems to stem from the widespread use of the corrected geomagnetic and invariant coordinate systems. These systems involve the mapping of field lines and have advantages in statistical studies and comparisons; less sophisticated systems such as the eccentric dipole coordinate system should be used in individual studies and in studies involving differentiation or integration of some observational parameters. Observations of the auraoral distribution are give to illustrate the universal time, tilt angle, and Kp variability in different coordinate systems and demonstrate that the dominant variability of the aurora is due to internal field asymmetries. A new set of coordinate systems are briefly developed as examples of how to incorporate external field models into studies of auraoral images. It is proposed that the one of these coordinate systems can be used as a test of how well an external field model can match observed auroral distributions. 19 refs., 1 tab

Site selection of active damper for stabilizing power electronics based power distribution system

DEFF Research Database (Denmark)

Yoon, Changwoo; Wang, Xiongfei; Bak, Claus Leth

2015-01-01

electronics based power device, which provides an adjustable damping capability to the power system where the voltage harmonic instability is measured. It can stabilize by adjusting the equivalent node impedance with its plug and play feature. This feature gives many degrees of freedom of its installation......Stability in the nowadays distribution power system is endangered by interaction problems that may arise from newly added power-electronics based power devices. Recently, a new concept to deal with this higher frequency instability, the active damper, has been proposed. The active damper is a power...... point when the system has many nodes. Therefore, this paper addresses the proper placement of an active damper in an unstable small-scale power distribution system. A time-domain model of the Cigre benchmark low-vltage network is used as a test field. The result shows the active damper location...

Zero Distribution of System with Unknown Random Variables Case Study: Avoiding Collision Path

Directory of Open Access Journals (Sweden)

Parman Setyamartana

2014-07-01

Full Text Available This paper presents the stochastic analysis of finding the feasible trajectories of robotics arm motion at obstacle surrounding. Unknown variables are coefficients of polynomials joint angle so that the collision-free motion is achieved. ãk is matrix consisting of these unknown feasible polynomial coefficients. The pattern of feasible polynomial in the obstacle environment shows as random. This paper proposes to model the pattern of this randomness values using random polynomial with unknown variables as coefficients. The behavior of the system will be obtained from zero distribution as the characteristic of such random polynomial. Results show that the pattern of random polynomial of avoiding collision can be constructed from zero distribution. Zero distribution is like building block of the system with obstacles as uncertainty factor. By scale factor k, which has range, the random coefficient pattern can be predicted.

Supervisor localization a top-down approach to distributed control of discrete-event systems

CERN Document Server

Cai, Kai

2016-01-01

This monograph presents a systematic top-down approach to distributed control synthesis of discrete-event systems (DES). The approach is called supervisor localization; its essence is the allocation of external supervisory control action to individual component agents as their internal control strategies. The procedure is: first synthesize a monolithic supervisor, to achieve globally optimal and nonblocking controlled behavior, then decompose the monolithic supervisor into local controllers, one for each agent. The collective behavior of the resulting local controllers is identical to that achieved by the monolithic supervisor. The basic localization theory is first presented in the Ramadge–Wonham language-based supervisory control framework, then demonstrated with distributed control examples of multi-robot formations, manufacturing systems, and distributed algorithms. An architectural approach is adopted to apply localization to large-scale DES; this yields a heterarchical localization procedure, which is...

Scaling Law for Irreversible Entropy Production in Critical Systems.

Science.gov (United States)

Hoang, Danh-Tai; Prasanna Venkatesh, B; Han, Seungju; Jo, Junghyo; Watanabe, Gentaro; Choi, Mahn-Soo

2016-06-09

We examine the Jarzynski equality for a quenching process across the critical point of second-order phase transitions, where absolute irreversibility and the effect of finite-sampling of the initial equilibrium distribution arise in a single setup with equal significance. We consider the Ising model as a prototypical example for spontaneous symmetry breaking and take into account the finite sampling issue by introducing a tolerance parameter. The initially ordered spins become disordered by quenching the ferromagnetic coupling constant. For a sudden quench, the deviation from the Jarzynski equality evaluated from the ideal ensemble average could, in principle, depend on the reduced coupling constant ε0 of the initial state and the system size L. We find that, instead of depending on ε0 and L separately, this deviation exhibits a scaling behavior through a universal combination of ε0 and L for a given tolerance parameter, inherited from the critical scaling laws of second-order phase transitions. A similar scaling law can be obtained for the finite-speed quench as well within the Kibble-Zurek mechanism.

The THUDSOS Distributed Operating System

Institute of Scientific and Technical Information of China (English)

廖先Zhi; 刘旭峰; 等

1991-01-01

The THUDSOS is a distributed operating system modeled as an abstract machine which provides decentralized control,transparency,availability,and reliability,as welol as a good degree of autonomy at each node,that makes our distributed system usable.Our operating system supports transparent access to data through network wide filesystem.The simultaneous access to any device is discussed for the case when the peripherals are treated as files.This operating system allows spawning of parallel application programs to solve problems in the fields,such as numerical analysis and artificial intelligence.

Landscape-scale distribution and persistence of genetically modified oilseed rape (Brassica napus) in Manitoba, Canada.

Science.gov (United States)

Knispel, Alexis L; McLachlan, Stéphane M

2010-01-01

adjacent field planted to OSR. Within roadside habitats, escaped OSR was also strongly associated with large-scale variables, including road surface (indicative of traffic intensity) and distance to the nearest grain elevator. Conversely, within field edges, OSR density was affected by localised crop management practices such as mowing, soil disturbance and herbicide application. Despite the proximity of roadsides and field edges, there was little evidence of spatial aggregation among escaped OSR populations in these two habitats, especially at very fine spatial scales (i.e. important determinants of the distribution of escaped GM crops. At the regional level, these factors ensure ongoing establishment and spread of escaped GMHT OSR despite limited local seed dispersal. Escaped populations thus play an important role in the spread of transgenes and have substantial implications for the coexistence of GM and non-GM production systems. Given the large-scale factors driving the spread of escaped transgenes, localised co-existence measures may be impracticable where they are not commensurate with regional dispersal mechanisms. To be effective, strategies aimed at reducing contamination from GM crops should be multi-scale in approach and be developed and implemented at both farm and landscape levels of organisation. Multiple stakeholders should thus be consulted, including both GM and non-GM farmers, as well as seed developers, processors, transporters and suppliers. Decisions to adopt GM crops require thoughtful and inclusive consideration of the risks and responsibilities inherent in this new technology.

Strategy Guideline. Compact Air Distribution Systems

Energy Technology Data Exchange (ETDEWEB)

Burdick, Arlan [IBACOS, Inc., Pittsburgh, PA (United States)

2013-06-01

This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

Distributed Semidefinite Programming with Application to Large-scale System Analysis

DEFF Research Database (Denmark)

Khoshfetrat Pakazad, Sina; Hansson, Anders; Andersen, Martin S.

2017-01-01

Distributed algorithms for solving coupled semidefinite programs (SDPs) commonly require many iterations to converge. They also put high computational demand on the computational agents. In this paper we show that in case the coupled problem has an inherent tree structure, it is possible to devis...

Incipient multiple fault diagnosis in real time with applications to large-scale systems

International Nuclear Information System (INIS)

Chung, H.Y.; Bien, Z.; Park, J.H.; Seon, P.H.

1994-01-01

By using a modified signed directed graph (SDG) together with the distributed artificial neutral networks and a knowledge-based system, a method of incipient multi-fault diagnosis is presented for large-scale physical systems with complex pipes and instrumentations such as valves, actuators, sensors, and controllers. The proposed method is designed so as to (1) make a real-time incipient fault diagnosis possible for large-scale systems, (2) perform the fault diagnosis not only in the steady-state case but also in the transient case as well by using a concept of fault propagation time, which is newly adopted in the SDG model, (3) provide with highly reliable diagnosis results and explanation capability of faults diagnosed as in an expert system, and (4) diagnose the pipe damage such as leaking, break, or throttling. This method is applied for diagnosis of a pressurizer in the Kori Nuclear Power Plant (NPP) unit 2 in Korea under a transient condition, and its result is reported to show satisfactory performance of the method for the incipient multi-fault diagnosis of such a large-scale system in a real-time manner

A Half-Bridge Voltage Balancer with New Controller for Bipolar DC Distribution Systems

Directory of Open Access Journals (Sweden)

Byung-Moon Han

2016-03-01

Full Text Available This paper proposes a half-bridge voltage balancer with a new controller for bipolar DC distribution systems. The proposed control scheme consists of two cascaded Proportional Integral (PI controls rather than one PI control for balancing the pole voltage. In order to confirm the excellence of voltage balancing performance, a typical bipolar DC distribution system including a half-bridge voltage balancer with proposed controller was analyzed by computer simulations. Experiments with a scaled prototype were also carried out to confirm the simulation results. The half-bridge voltage balancer with proposed controller shows better performance than the half-bridge voltage balancer with one PI control for balancing the pole voltage.

On the Distribution of Earthquake Interevent Times and the Impact of Spatial Scale

Science.gov (United States)

Hristopulos, Dionissios

2013-04-01

The distribution of earthquake interevent times is a subject that has attracted much attention in the statistical physics literature [1-3]. A recent paper proposes that the distribution of earthquake interevent times follows from the the interplay of the crustal strength distribution and the loading function (stress versus time) of the Earth's crust locally [4]. It was also shown that the Weibull distribution describes earthquake interevent times provided that the crustal strength also follows the Weibull distribution and that the loading function follows a power-law during the loading cycle. I will discuss the implications of this work and will present supporting evidence based on the analysis of data from seismic catalogs. I will also discuss the theoretical evidence in support of the Weibull distribution based on models of statistical physics [5]. Since other-than-Weibull interevent times distributions are not excluded in [4], I will illustrate the use of the Kolmogorov-Smirnov test in order to determine which probability distributions are not rejected by the data. Finally, we propose a modification of the Weibull distribution if the size of the system under investigation (i.e., the area over which the earthquake activity occurs) is finite with respect to a critical link size. keywords: hypothesis testing, modified Weibull, hazard rate, finite size References [1] Corral, A., 2004. Long-term clustering, scaling, and universality in the temporal occurrence of earthquakes, Phys. Rev. Lett., 9210) art. no. 108501. [2] Saichev, A., Sornette, D. 2007. Theory of earthquake recurrence times, J. Geophys. Res., Ser. B 112, B04313/1-26. [3] Touati, S., Naylor, M., Main, I.G., 2009. Origin and nonuniversality of the earthquake interevent time distribution Phys. Rev. Lett., 102 (16), art. no. 168501. [4] Hristopulos, D.T., 2003. Spartan Gibbs random field models for geostatistical applications, SIAM Jour. Sci. Comput., 24, 2125-2162. [5] I. Eliazar and J. Klafter, 2006

Comparison of the Frontier Distributed Database Caching System with NoSQL Databases

CERN Multimedia

CERN. Geneva

2012-01-01

Non-relational "NoSQL" databases such as Cassandra and CouchDB are best known for their ability to scale to large numbers of clients spread over a wide area. The Frontier distributed database caching system, used in production by the Large Hadron Collider CMS and ATLAS detector projects, is based on traditional SQL databases but also has the same high scalability and wide-area distributability for an important subset of applications. This paper compares the architectures, behavior, performance, and maintainability of the two different approaches and identifies the criteria for choosing which approach to prefer over the other.

Novel scaling of the multiplicity distributions in the sequential fragmentation process and in the percolation

International Nuclear Information System (INIS)

Botet, R.

1996-01-01

A novel scaling of the multiplicity distributions is found in the shattering phase of the sequential fragmentation process with inhibition. The same scaling law is shown to hold in the percolation process. (author)

Coordinated Optimization of Distributed Energy Resources and Smart Loads in Distribution Systems: Preprint

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui; Zhang, Yingchen

2016-08-01

Distributed energy resources (DERs) and smart loads have the potential to provide flexibility to the distribution system operation. A coordinated optimization approach is proposed in this paper to actively manage DERs and smart loads in distribution systems to achieve the optimal operation status. A three-phase unbalanced Optimal Power Flow (OPF) problem is developed to determine the output from DERs and smart loads with respect to the system operator's control objective. This paper focuses on coordinating PV systems and smart loads to improve the overall voltage profile in distribution systems. Simulations have been carried out in a 12-bus distribution feeder and results illustrate the superior control performance of the proposed approach.

Validation of model predictions of pore-scale fluid distributions during two-phase flow

Science.gov (United States)

Bultreys, Tom; Lin, Qingyang; Gao, Ying; Raeini, Ali Q.; AlRatrout, Ahmed; Bijeljic, Branko; Blunt, Martin J.

2018-05-01

Pore-scale two-phase flow modeling is an important technology to study a rock's relative permeability behavior. To investigate if these models are predictive, the calculated pore-scale fluid distributions which determine the relative permeability need to be validated. In this work, we introduce a methodology to quantitatively compare models to experimental fluid distributions in flow experiments visualized with microcomputed tomography. First, we analyzed five repeated drainage-imbibition experiments on a single sample. In these experiments, the exact fluid distributions were not fully repeatable on a pore-by-pore basis, while the global properties of the fluid distribution were. Then two fractional flow experiments were used to validate a quasistatic pore network model. The model correctly predicted the fluid present in more than 75% of pores and throats in drainage and imbibition. To quantify what this means for the relevant global properties of the fluid distribution, we compare the main flow paths and the connectivity across the different pore sizes in the modeled and experimental fluid distributions. These essential topology characteristics matched well for drainage simulations, but not for imbibition. This suggests that the pore-filling rules in the network model we used need to be improved to make reliable predictions of imbibition. The presented analysis illustrates the potential of our methodology to systematically and robustly test two-phase flow models to aid in model development and calibration.

Scaling-Laws of Flow Entropy with Topological Metrics of Water Distribution Networks

OpenAIRE

Giovanni Francesco Santonastaso; Armando Di Nardo; Michele Di Natale; Carlo Giudicianni; Roberto Greco

2018-01-01

Robustness of water distribution networks is related to their connectivity and topological structure, which also affect their reliability. Flow entropy, based on Shannon’s informational entropy, has been proposed as a measure of network redundancy and adopted as a proxy of reliability in optimal network design procedures. In this paper, the scaling properties of flow entropy of water distribution networks with their size and other topological metrics are studied. To such aim, flow entropy, ma...

Equilibrium distribution function in collisionless systems

International Nuclear Information System (INIS)

Pergamenshchik, V.M.

1988-01-01

Collisionless systems of a large number of N particles interacting by Coulomb forces are widely spread in cosmic and laboratory plasma. A statistical theory of equilibrium state of collisionless Coulomb systems which evolution obeys Vlasov equation is proposed. The developed formalism permits a sequential consideration of such distributed in one-particle six-dimensional phase space of a system and to obtain a simple result: equilibrium distribution function has the form of Fermi-Dirac distribution and doesn't depend on initial state factors

On Distributed Port-Hamiltonian Process Systems

NARCIS (Netherlands)

Lopezlena, Ricardo; Scherpen, Jacquelien M.A.

2004-01-01

In this paper we use the term distributed port-Hamiltonian Process Systems (DPHPS) to refer to the result of merging the theory of distributed Port-Hamiltonian systems (DPHS) with the theory of process systems (PS). Such concept is useful for combining the systematic interconnection of PHS with the

Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation

Energy Technology Data Exchange (ETDEWEB)

Faress Rahman; Nguyen Minh

2004-01-04

This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the July 2003 to December 2003 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. Also, another activity included in this program focuses on the development of SOFC scale up strategies.

A Heuristic Approach to Distributed Generation Source Allocation for Electrical Power Distribution Systems

Directory of Open Access Journals (Sweden)

M. Sharma

2010-12-01

Full Text Available The recent trends in electrical power distribution system operation and management are aimed at improving system conditions in order to render good service to the customer. The reforms in distribution sector have given major scope for employment of distributed generation (DG resources which will boost the system performance. This paper proposes a heuristic technique for allocation of distribution generation source in a distribution system. The allocation is determined based on overall improvement in network performance parameters like reduction in system losses, improvement in voltage stability, improvement in voltage profile. The proposed Network Performance Enhancement Index (NPEI along with the heuristic rules facilitate determination of feasible location and corresponding capacity of DG source. The developed approach is tested with different test systems to ascertain its effectiveness.

Review on Islanding Operation of Distribution System with Distributed Generation

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2011-01-01

The growing environmental concern and various benefits of distributed generation (DG) have resulted in significant penetration of DG in many distribution systems worldwide. One of the major expected benefits of DG is the improvement in the reliability of power supply by supplying load during power...... outage by operating in an island mode. However, there are many challenges to overcome before islanding operation of a distribution system with DG can become a viable solution in future. This paper reviews some of the major challenges with islanding operation and explores some possible solutions...

Tools for the Automation of Large Distributed Control Systems

CERN Document Server

Gaspar, Clara

2005-01-01

The new LHC experiments at CERN will have very large numbers of channels to operate. In order to be able to configure and monitor such large systems, a high degree of parallelism is necessary. The control system is built as a hierarchy of sub-systems distributed over several computers. A toolkit - SMI++, combining two approaches: finite state machines and rule-based programming, allows for the description of the various sub-systems as decentralized deciding entities, reacting is real-time to changes in the system, thus providing for the automation of standard procedures and for the automatic recovery from error conditions in a hierarchical fashion. In this paper we will describe the principles and features of SMI++ as well as its integration with an industrial SCADA tool for use by the LHC experiments and we will try to show that such tools, can provide a very convenient mechanism for the automation of large scale, high complexity, applications.

The impact of small scale cogeneration on the gas demand at distribution level

International Nuclear Information System (INIS)

Vandewalle, J.; D’haeseleer, W.

2014-01-01

Highlights: • Impact on the gas network of a massive implementation of cogeneration. • Distributed energy resources in a smart grid environment. • Optimisation of cogeneration scheduling. - Abstract: Smart grids are often regarded as an important step towards the future energy system. Combined heat and power (CHP) or cogeneration has several advantages in the context of the smart grid, which include the efficient use of primary energy and the reduction of electrical losses through transmission. However, the role of the gas network is often overlooked in this context. Therefore, this work presents an analysis of the impact of a massive implementation of small scale (micro) cogeneration units on the gas demand at distribution level. This work shows that using generic information in the simulations overestimates the impact of CHP. Furthermore, the importance of the thermal storage tank capacity on the impact on the gas demand is shown. Larger storage tanks lead to lower gas demand peaks and hence a lower impact on the gas distribution network. It is also shown that the use of an economically led controller leads to similar results compared to classical heat led control. Finally, it results that a low sell back tariff for electricity increases the impact of cogeneration on the gas demand peak

SCALE Code System 6.2.2

Energy Technology Data Exchange (ETDEWEB)

Rearden, Bradley T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jessee, Matthew Anderson [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-05-01

The SCALE Code System is a widely used modeling and simulation suite for nuclear safety analysis and design that is developed, maintained, tested, and managed by the Reactor and Nuclear Systems Division (RNSD) of Oak Ridge National Laboratory (ORNL). SCALE provides a comprehensive, verified and validated, user-friendly tool set for criticality safety, reactor physics, radiation shielding, radioactive source term characterization, and sensitivity and uncertainty analysis. Since 1980, regulators, licensees, and research institutions around the world have used SCALE for safety analysis and design. SCALE provides an integrated framework with dozens of computational modules including 3 deterministic and 3 Monte Carlo radiation transport solvers that are selected based on the desired solution strategy. SCALE includes current nuclear data libraries and problem-dependent processing tools for continuous-energy (CE) and multigroup (MG) neutronics and coupled neutron-gamma calculations, as well as activation, depletion, and decay calculations. SCALE includes unique capabilities for automated variance reduction for shielding calculations, as well as sensitivity and uncertainty analysis. SCALE’s graphical user interfaces assist with accurate system modeling, visualization of nuclear data, and convenient access to desired results. SCALE 6.2 represents one of the most comprehensive revisions in the history of SCALE, providing several new capabilities and significant improvements in many existing features.

SCALE Code System 6.2.1

International Nuclear Information System (INIS)

Rearden, Bradley T.; Jessee, Matthew Anderson

2016-01-01

The SCALE Code System is a widely-used modeling and simulation suite for nuclear safety analysis and design that is developed, maintained, tested, and managed by the Reactor and Nuclear Systems Division (RNSD) of Oak Ridge National Laboratory (ORNL). SCALE provides a comprehensive, verified and validated, user-friendly tool set for criticality safety, reactor and lattice physics, radiation shielding, spent fuel and radioactive source term characterization, and sensitivity and uncertainty analysis. Since 1980, regulators, licensees, and research institutions around the world have used SCALE for safety analysis and design. SCALE provides an integrated framework with dozens of computational modules including three deterministic and three Monte Carlo radiation transport solvers that are selected based on the desired solution strategy. SCALE includes current nuclear data libraries and problem-dependent processing tools for continuous-energy (CE) and multigroup (MG) neutronics and coupled neutron-gamma calculations, as well as activation, depletion, and decay calculations. SCALE includes unique capabilities for automated variance reduction for shielding calculations, as well as sensitivity and uncertainty analysis. SCALE's graphical user interfaces assist with accurate system modeling, visualization of nuclear data, and convenient access to desired results.

Effectiveness of Devices to Monitor Biofouling and Metals Deposition on Plumbing Materials Exposed to a Full-Scale Drinking Water Distribution System.

Science.gov (United States)

Ginige, Maneesha P; Garbin, Scott; Wylie, Jason; Krishna, K C Bal

2017-01-01

A Modified Robbins Device (MRD) was installed in a full-scale water distribution system to investigate biofouling and metal depositions on concrete, high-density polyethylene (HDPE) and stainless steel surfaces. Bulk water monitoring and a KIWA monitor (with glass media) were used to offline monitor biofilm development on pipe wall surfaces. Results indicated that adenosine triphosphate (ATP) and metal concentrations on coupons increased with time. However, bacterial diversities decreased. There was a positive correlation between increase of ATP and metal deposition on pipe surfaces of stainless steel and HDPE and no correlation was observed on concrete and glass surfaces. The shared bacterial diversity between bulk water and MRD was less than 20% and the diversity shared between the MRD and KIWA monitor was only 10%. The bacterial diversity on biofilm of plumbing material of MRD however, did not show a significant difference suggesting a lack of influence from plumbing material during early stage of biofilm development.

Effectiveness of Devices to Monitor Biofouling and Metals Deposition on Plumbing Materials Exposed to a Full-Scale Drinking Water Distribution System.

Directory of Open Access Journals (Sweden)

Maneesha P Ginige

Full Text Available A Modified Robbins Device (MRD was installed in a full-scale water distribution system to investigate biofouling and metal depositions on concrete, high-density polyethylene (HDPE and stainless steel surfaces. Bulk water monitoring and a KIWA monitor (with glass media were used to offline monitor biofilm development on pipe wall surfaces. Results indicated that adenosine triphosphate (ATP and metal concentrations on coupons increased with time. However, bacterial diversities decreased. There was a positive correlation between increase of ATP and metal deposition on pipe surfaces of stainless steel and HDPE and no correlation was observed on concrete and glass surfaces. The shared bacterial diversity between bulk water and MRD was less than 20% and the diversity shared between the MRD and KIWA monitor was only 10%. The bacterial diversity on biofilm of plumbing material of MRD however, did not show a significant difference suggesting a lack of influence from plumbing material during early stage of biofilm development.

Large-Scale Optimization for Bayesian Inference in Complex Systems

Energy Technology Data Exchange (ETDEWEB)

Willcox, Karen [MIT; Marzouk, Youssef [MIT

2013-11-12

The SAGUARO (Scalable Algorithms for Groundwater Uncertainty Analysis and Robust Optimization) Project focused on the development of scalable numerical algorithms for large-scale Bayesian inversion in complex systems that capitalize on advances in large-scale simulation-based optimization and inversion methods. The project was a collaborative effort among MIT, the University of Texas at Austin, Georgia Institute of Technology, and Sandia National Laboratories. The research was directed in three complementary areas: efficient approximations of the Hessian operator, reductions in complexity of forward simulations via stochastic spectral approximations and model reduction, and employing large-scale optimization concepts to accelerate sampling. The MIT--Sandia component of the SAGUARO Project addressed the intractability of conventional sampling methods for large-scale statistical inverse problems by devising reduced-order models that are faithful to the full-order model over a wide range of parameter values; sampling then employs the reduced model rather than the full model, resulting in very large computational savings. Results indicate little effect on the computed posterior distribution. On the other hand, in the Texas--Georgia Tech component of the project, we retain the full-order model, but exploit inverse problem structure (adjoint-based gradients and partial Hessian information of the parameter-to-observation map) to implicitly extract lower dimensional information on the posterior distribution; this greatly speeds up sampling methods, so that fewer sampling points are needed. We can think of these two approaches as ``reduce then sample'' and ``sample then reduce.'' In fact, these two approaches are complementary, and can be used in conjunction with each other. Moreover, they both exploit deterministic inverse problem structure, in the form of adjoint-based gradient and Hessian information of the underlying parameter-to-observation map, to

Aerogel-Based Insulation for Industrial Steam Distribution Systems

Energy Technology Data Exchange (ETDEWEB)

John Williams

2011-03-30

Thermal losses in industrial steam distribution systems account for 977 trillion Btu/year in the US, more than 1% of total domestic energy consumption. Aspen Aerogels worked with Department of Energy’s Industrial Technologies Program to specify, develop, scale-up, demonstrate, and deliver Pyrogel XT®, an aerogel-based pipe insulation, to market to reduce energy losses in industrial steam systems. The product developed has become Aspen’s best selling flexible aerogel blanket insulation and has led to over 60 new jobs. Additionally, this product has delivered more than ~0.7 TBTU of domestic energy savings to date, and could produce annual energy savings of 149 TBTU by 2030. Pyrogel XT’s commercial success has been driven by it’s 2-4X better thermal performance, improved durability, greater resistance to corrosion under insulation (CUI), and faster installation times than incumbent insulation materials.