Julien M. Amelot

An IEEE 1588 time synchronization testbed for assessing power distribution requirements

Wide-area monitoring (WAM) applications for power distribution rely on accurate global time synchronization. Furthermore, there is interest in replacing current time synchronization methods such as Inter Range Instrumentation Group (IRIG), with distributed time synchronization protocols that utilize the data communication lines eliminating the need for dedicated timing signals within the substation. By understanding the factors impacting synchronization performance, the testbed facilitates the characterization of metrics needed to meet industry requirements. The testbed provides an experimental venue to explore IEEE 1588 Precision Time Protocol (PTP) technologies and determine how new features and requirements for time synchronization can impact the performance of next-generation power distribution applications. Initial results indicate PTP has the capabilities to support an accurate and scalable time synchronization solution given the components are interoperable.

Terabyte-sized image computations on Hadoop cluster platforms

We present a characterization of four basic Terabyte-sized image computations on a Hadoop cluster in terms of their relative efficiency according to the modified Amdahls law. The work is motivated by the lack of standard benchmarks and stress tests for big image processing operations on a Hadoop computer cluster platform. Our benchmark design and evaluations were performed on one of the three microscopy image sets, each consisting of over one half Terabyte. All image processing benchmarks executed on the NIST Raritan cluster with Hadoop were compared against baseline measurements, such as the Terasort/Teragen designed for Hadoop testing previously, image processing executions on a multiprocessor desktop and on NIST Raritan cluster using Java Remote Method Invocation (RMI) with multiple configurations. By applying our methodology to assessing efficiencies of computations on computer cluster configurations, we could rank computation configurations and aid scientists in measuring the benefits of running image processing on a Hadoop cluster.

An IEEE 1588 Performance Testing Dashboard for Power Industry requirements

The numerous time synchronization performance requirements in the Smart Grid necessitates a set of common metrics and test methods. The test methods help to verify the ability of the network system and its components to meet the power industrys accuracy, reliability and interoperability criteria for next-generation substations. In order to develop viable metrics and test methods, an IEEE 1588 Testbed for the power industry has been established. To ease the challenges of testing, monitoring and analysis of the results, a software-based testing dashboard was designed and implemented. The dashboard streamlines the performance testing process by converging multiple tests for accuracy, reliability and interoperability into a centralized interface. The dashboard enables real-time visualization and analysis of the results. The paper details the design and implementation of the IEEE 1588 Power Industry Performance Testing Dashboard as well as an update of the preliminary findings from the testbed.

Large-scale time-lapse microscopy of Oct4 expression in human embryonic stem cell colonies.

Identification and quantification of the characteristics of stem cell preparations is critical for understanding stem cell biology and for the development and manufacturing of stem cell based therapies. We have developed image analysis and visualization software that allows effective use of time-lapse microscopy to provide spatial and dynamic information from large numbers of human embryonic stem cell colonies. To achieve statistically relevant sampling, we examined >680 colonies from 3 different preparations of cells over 5 days each, generating a total experimental dataset of 0.9 terabyte (TB). The 0.5 Giga-pixel images at each time point were represented by multi-resolution pyramids and visualized using the Deep Zoom Javascript library extended to support viewing Giga-pixel images over time and extracting data on individual colonies. We present a methodology that enables quantification of variations in nominally-identical preparations and between colonies, correlation of colony characteristics with Oct4 expression, and identification of rare events.

An IEEE 1588 performance testing dashboard for power industry requirements

The numerous time synchronization performance requirements in the Smart Grid necessitates a set of common metrics and test methods. The test methods help to verify the ability of the network system and its components to meet the power industrys accuracy, reliability and interoperability criteria for next-generation substations. In order to develop viable metrics and test methods, an IEEE 1588 Testbed for the power industry has been established. To ease the challenges of testing, monitoring and analysis of the results, a software-based testing dashboard was designed and implemented. The dashboard streamlines the performance testing process by converging multiple tests for accuracy, reliability and interoperability into a centralized interface. The dashboard enables real-time visualization and analysis of the results. The paper details the design and implementation of the IEEE 1588 Power Industry Performance Testing Dashboard as well as an update of the preliminary findings from the testbed.

Using clock accuracy to guide model synthesis in distributed systems: An application in power grid control

Practical implementations in distributed model based control face a fundamental trade-off between model complexity and the number of modeled nodes. For linear systems, higher order models better capture the behavior of the system at higher frequencies, but the effective operating frequency range is limited during implementation due to sensor/actuator bandwidth limits, control algorithm limits and, in the case of wide scale distribution, communication bandwidth limits. The optimal choice for model order is the intersection of increasing model fidelity and the increasing generalized cost. Using existing methods for optimal model synthesis we present an evaluation of this cost in terms of clock synchronization accuracy. We show through illustrative example in the domain of large scale power transmission that there is a growing performance penalty as model order is increased in the presence of uncertain time-stamps. We discuss how this penalty can be framed as a design parameter for automated model deduction. As a corollary, we also show that the choice of a network based clock synchronization method can be formalized by using the same performance metric used for model synthesis.

Testing phasor measurement units using IEEE 1588 precision time protocol

As the electric power grid is changing to a smarter more dynamically controlled system, there is increasing need for measurements that show the global status of the system for wide-area monitoring and control. These measurements require time synchronization across the grid. This synchronization is obtained by the use of GPS clocks. As the number of such synchronized devices increases there is a need to have an efficient, accurate, and reliable method of time distribution within power substations. The power industry is increasingly turning to the use of IEEE 1588 network Precision Time Protocol to meet this need in substation Intelligent Electronic Devices (IEDs). This paper examines this need in relation to the use of Phasor Measurement Units. This also paper describes the errors associated with this protocol and its application to the calibration of PMUs.

Enabling Stem Cell Characterization from Large Microscopy Images

Microscopy could be an important tool for characterizing stem cell products if quantitative measurements could be collected over multiple spatial and temporal scales. With the cells changing states over time and being several orders of magnitude smaller than cell products, modern microscopes are already capable of imaging large spatial areas, repeat imaging over time, and acquiring images over several spectra. However, characterizing stem cell products from such large image collections is challenging because of data size, required computations, and lack of interactive quantitative measurements needed to determine release criteria. We present a measurement web system consisting of available algorithms, extensions to a client-server framework using Deep Zoom, and the configuration know-how to provide the information needed for inspecting the quality of a cell product. The cell and other data sets are accessible via the prototype web-based system at http://isg.nist.gov/deepzoomweb.Microscopes can now cover large spatial areas and capture stem cell behavior over time. However, without discovering statistically reliable quantitative stem cell quality measures, products cannot be released to market. A Web-based measurement system overcomes desktop limitations by leveraging cloud and cluster computing for offline computations and by using Deep Zoom extensions for interactive viewing and measurement.

Smart clocks have a hand in the smart grid

Clock synchronization is becoming an increasingly important characteristic of modern wide area monitoring and control systems such as the power grid. It provides an opportunity to coordinate control actions and measurement instants across hundreds of miles and numerous network topologies. Devices and networks have advanced to a point where synchronization across a wide area can be achieved within 1 μs of UTC (Coordinated Universal Time). Along with these advances in clock synchronization must come a shift in the way analysis is performed. Modeling techniques must incorporate the effects of a clock synchronized device, and control techniques can leverage the knowledge of ”time” to achieve unique results. This paper discusses various ways in which clock synchronization affects analysis and performance of the power grid, and presents a few projects related to the technology. Preliminary work has demonstrated the ability of various commercially available devices to provide reliable 1 μs synchronization of clocks, and large variation across devices in terms of clock performance under transient events.

Machine learning and interactive visualization applied to TB-sized images of stem cells

In order to characterize the growth and properties of stem cell colonies with high statistical significance, we address the problem of applying machine learning and interactive web visualizations to TB-sized images. Overcoming the computational challenges and designing advanced visualizations enabled knowledge discovery and quantitative analysis at unprecedented scales in cell microscopy.