Transcript Document
Distributed Hybrid Earthquake Engineering Experiments: Experiences with a Ground-Shaking Grid Application Laura Pearlman, Carl Kesselman, Sridhar Gullapalli USC Information Sciences Institute B.F. Spencer, UIUC Ian Foster, Paul Hubbard, ANL Chuck Severance, University of Michigan Joe Futrelle, Kathleen Ricker, NCSA [email protected] NEESgrid • NEES: NSF-funded project in support of earthquake engineering. • NEESgrid: National earthquake engineering collaboratory – Deployment complete September 30, 2004 – Operational through 2014 • This talk is an overview of one application of NEESgrid. Outline • The Application: Distributed Hybrid Experiments • Architecture • Experiences: The MOST Experiment • Security Considerations • Related Work • Conclusions Traditional Methods • Computational Simulations • Physical Experiments Physica l System – Build and instrument a specimen. – Subject it to forces. – Record sensor measurements throughout Control / Data the experiment. Acquisition System Physical Testing Apparatus Characteristics of Physical Experiments • Specimens can be large-scale (50 tons or more) • Take months to construct • Some steps can’t be “undone” • Require specialized equipment and facilities Hybrid Experiments Physica l System Computational Simulation Control / Data Acquisition System Pre-NEESgrid Hybrid Experiments • Physical and computational simulations occur at same site, usually with communication via a shared memory backbone such as SCRAMnet. • Proprietary communication protocol between the computational and physical system Soil-Structure Test Structural Computation Geotechnical Computation Structural Experiment Geotechnical Experiment Structural Experiment Distributed Hybrid Experiment Characteristics • Multiple physical experiments – At different geographic sites – Resources owned by different organizations – Heterogeneous control platforms • Multiple computational simulations – – – – At different geographic sites Resources owned by different organizations Heterogeneous simulation platforms Sometimes used in place of physical experiments Experiment Variations Full-scale LBCB 1/5th-scale LBCB LBCB simulator (Computer Model) NEESgrid Services Control System Control client telecontrol Observers Physica l System DAQ System streaming data Files NEES-POP Equipment Site Files Web portal Ingestion tool Data/ metadata Repository, Credential cache Central Services Telecontrol Service Requirements • Uniform interface for heterogeneous systems • Impose minimal requirements on control systems. • Support for recovery from transient errors • Performance requirements vary widely (1 ms for some experiments; 10 seconds for others). NEESgrid Teleoperation Control Protocol (NTCP) • Transaction-based • State model – provides for at-most-once execution – guarantees that a control point is doing at most one thing at a time – guarantees that requests involving any control point are executed in the order received • Protocol allows for negotiation of request parameters prior to execution. NTCP Plugins Control System B Control System A Plugin NTCP Client NTCP Plugin NTCP Plugin Simulation Multi-site Online Simulation Test (MOST) • First distributed hybrid experiment in NEESgrid (and, we believe, in the US). • Combined physical experiments at the University of Illinois (UIUC) and University of Colorado (CU) with a simulation at NCSA. • Simulations and experiments created by earthquake engineers at UIUC and CU. The MOST Structure SAC Consortium Benchmark Structure Moment Connections xg Pinned Connection The MOST Substructures UIUC Experimental Model U. Colorado Experimental Model NCSA Computational Model m1 f1 f2 f1 f2 m1 xg xg xg Slide courtesy of Bill Spencer and Narutoshi Nakata, UIUC Computation-Only Test Colorado NTCP Server Mplugin CU Simulation Simulation Coordinator Mplugin NCSA Simulation NTCP Server NTCP Server NCSA UIUC Mplugin UIUC Simulation MOST Components Colorado NTCP Server Mplugin Matlab (xPC host) Matlab (xPC target) Coordinating Simulation Mplugin NCSA Simulation NTCP Shore-Western Server Plugin NTCP Server NCSA UIUC Control Components in MOST NTCP Matlab toolbox NTCP NTCP Server Java API Mplugin Matlab toolbox Shore-Western Mplugin Mplugin Plugin Java API NTCP Plugin Interface Globus Toolkit version 3 The MOST Event Mini-MOST Security Considerations NTCP Security Features • Authentication via GSI • Authorization via gridmap lookups and a policy plugin. • Control plugin architecture allows for running control system on a separate host, isolated behind a firewall • Control plugin also allows for setting of local limits. Ongoing NEES Experiments • Fast-MOST: Berkeley, Buffalo, CU, and UIUC are performing a MOSTlike experiment with stricter performance requirements. • MISST: RPI, UIUC, Lehigh: soilstructure interaction. • UC-Davis: Soil study with remote control of a robot arm. Other Related Work • Multi-Site Pseudo-Dynamic Substructure Testing: – Method for dividing structures into substructures and testing separately – Developed in Japan in 1999 – MOST simulations are based on this method • TeleScience Portal – using NTCP to control electron microscopes. • NMI Common Instrument Middleware Architecture (CIMA) project Conclusions • Distributed hybrid earthquake engineering experiments are a “real” grid application. • NTCP works: – Earthquake engineers are developing and using their own clients and plugins. – Its failure-recovery features have allowed experiments to continue after transient network failures • But there’s still work to do… – NTCP requires some shared knowledge between developers of clients and plugins. Better use of service data could fix this. – Some aspects of the protocol need to be “cleaned up” – There’s not much support for recovering from backend failures. Acknowledgements Dan Abrams, Cristina Beldica, Ian Buckle, Ben Clifford, Mike D’Arcy, Amr Elnashai, Tom Finholt, David Gehrig, Tomasz Haupt, Dan Horn, Erik Johnson, Young Suk Kim, Dan Kuchma, Lee Liming, Ravi Madduri, Doru Marcusiu, Gilberto Mosqueda, Narutoshi Nakata, Gokhan Pekcan, Pawel Plaszczak, Tom Prudhomme, Chase Phillips, Andrei Reinhorn, Hatem A Seliem, Benson Shing, Eric Stauffer, Bozidar Stojadinovic, Guangqiang Yang, and Nestor Zaluzec. For More Information • NEESgrid web site: http://www.neesgrid.org