Bhuvan Urgaonkar's Papers

dblp | Google Scholar

Copyright notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.



pre'14b A Hierarchical Demand Response Framework for Data Center Power Cost Optimization Under Real-World Electricity Pricing.
Cheng Wang, Bhuvan Urgaonkar, Qian Wang, and George Kesidis.
Preprint, March 2014.
PDF


pre'14a A Case for Virtualizing the Electric Utility in Cloud Data Centers.
Cheng Wang, Bhuvan Urgaonkar, George Kesidis, Uday V. Shanbhag, and Qian Wang.
Preprint, January 2014.
PDF


jsc'14 HybridPlan: A Capacity Planning Technique for Projecting Storage Requirements in Hybrid Storage Systems.
Youngjae Kim, Aayush Gupta, Bhuvan Urgaonkar, Piotr Berman, and Anand Sivasubramaniam.
The Journal of Supercomputing, 67(1):277-303, January 2014.
Paper


ucc'13 Data Center Power Cost Optimization Via Workload Modulation.
Cheng Wang, Bhuvan Urgaonkar, Qian Wang, George Kesidis, and Anand Sivasubramaniam.
Proceedings of the Sixth IEEE/ACM International Conference on Uitlity and Cloud Computing (UCC'13) (short paper), Dresden, Germany, December 2013. Longer version: arXiv preprint arXiv:1308.0585. Also Technical Report 13-010 Dept. of CSE, Penn State, August 2013.
Paper       arXiv Preprint


ladis'13 Towards An Effective and General Resource Accounting and Control Framework in Consolidated IT Platforms.
Byung Chul Tak, Youngjin Kwon, and Bhuvan Urgaonkar.
Seventh Workshop on Large-Scale Distributed Systems and Middleware, (LADIS 2013), colocated with ACM SOSP, November 2013.


jcst'13 A Temporal Locality-aware Page-Mapped Flash Translation Layer.
Youngjae Kim, Aayush Gupta, and Bhuvan Urgaonkar.
Journal of Computer Science and Technology (JCST), 28(6), pp. 1025-1044, Nov. 2013.
Extends our ASPLOS 2009 paper.
Paper


mama'13 Pricing of Service in Clouds: Optimal Response and Strategic Interactions.
Bhuvan Urgaonkar, George Kesidis, Uday V. Shanbhag, and Cheng Wang.
Workshop on Mathematical performance Modeling and Analysis (MAMA 2013), co-located with ACM SIGMETRICS, Pittsburgh PA, June 2013.
Paper


dcperf'13 A Case For Heterogeneous Flash.
Di Wang, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
Workshop on Data Center Performance (DCPerf), co-located with IEEE ICDCS, Philadelphia PA, July 2013.
Invited Paper
Paper


tpds'13 Cloudy with a Chance of Cost Savings.
Byung Chul Tak, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 24, No. 6, pp. 1223-1233, June 2013.
Paper


hotos'13 Using Dark Fiber to Displace Diesel Generators.
Aman Kansal, Bhuvan Urgaonkar, and Sriram Govindan.
USENIX XIV Workshop on Hot Topics in Operating Systems (HotOS), Santa Ana Pueblo NM, May 2013. (27/90 = 30% accepted).
Paper


tocs'13 Aggressive Datacenter Power Provisioing Using Batteries.
Sriram Govindan, Di Wang, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
ACM Transactions on Computer Systems (TOCS), 31:1, pp. 2:1-2:31, February 2013.
Featured in CACM News: Link
Paper


socc'12 Using Batteries to Reduce the Power Costs of Internet-scale Distributed Networks.
Darshan S. Palasamudram, Ramesh K. Sitaraman, Bhuvan Urgaonkar, and Rahul Urgaonkar.
Proceedings of the Third ACM Symposium on Cloud Computing (SOCC 2012), San Jose, CA, October 2012. (21/163 = 13% accepted).
Paper


mascots'12 Carbon-Aware Energy Capacity Planning for Datacenters.
Chuangang Ren, Di Wang, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the IEEE International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS 2012), Washington DC, August 2012. (49/134 = 37% accepted).
Best Paper Award
Abstract       Paper


sigmetrics'12 Energy Storage in Datacenters: What, Where, and How Much?
Di Wang, Chuangang Ren, Anand Sivasubramaniam, Bhuvan Urgaonkar, and Hosam K. Fathy.
Proceedings of the ACM International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS 2012), pages 187-198, London, UK, June 2012. (31/203 = 15% accepted).
Nominated for Best Paper Award (one of 4 nominated papers)
Abstract       Paper


asplos'12 Leveraging Stored Energy for Handling Power Emergencies in Aggressively Provisioned Datacenters.
Sriram Govindan, Di Wang, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
Proceedings of the International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2012), pages 75-86, London, UK. March 2012. (37/172 = 21% accepted).
Pick of the Month (IEEE Sustainable Computing Register, October 2012).
Abstract       Paper


hotpower'11 Towards Realizing a Low Cost and Highly Available Datacenter Power Infrastructure.
Sriram Govindan, Di Wang, Lydia Chen, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
Proceedings of the Fourth Workshop on Power-Aware Computing and Systems (HOTPOWER 2011), co-located with ACM SOSP 2011, Cascais, Portugal, October 2011.
Abstract       Paper


ebr'11 Understanding the Cost of Cloud: Cost analysis of In-house vs. Cloud-based Hosting Options.
Byung Chul Tak, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
The European Business Review, Sep 2011, pages 76-80.
Paper


mascots'11 HybridStore: A Cost-Efficient, High-Performance Storage System Combining SSDs and HDDs.
Youngjae Kim, Aayush Gupta, Bhuvan Urgaonkar, Piotr Berman, and Anand Sivasubramaniam.
Proceedings of the Annual Meeting of the IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS 2011), pages 227-236, Singapore, July 2011. (41/157 = 26% accepted).
Also, Technical Report CSE-08-017 Department of Computer Science and Engineering, The Pennsylvania State University, September 2008.

Abstract     Paper


hotcloud'11 To Move or Not to Move: The Economics of Cloud Computing.
Byung Chul Tak, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the Third USENIX Workshop on Hot Topics in Cloud Computing (HOTCLOUD 2011), Portland, OR, June 2011. (23/72 = 31% accepted).
Also, Technical Report CSE-TR-11-002, Department of Computer Science and Engineering, The Pennsylvania State University.
Abstract     Paper

isca'11 Benefits and Limitations of Tapping into Stored Energy for Datacenters.
Sriram Govindan, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
Proceedings of the International Symposium on Computer Architecture (ISCA 2011), pages 341-352, San Jose, CA, June 2011. (40/208 = 19% accepted).
Abstract     Paper


sigmetrics'11 Optimal Power Cost Management Using Stored Energy in Data Centers.
Rahul Urgaonkar, Bhuvan Urgaonkar, Michael Neely, and Anand Sivasubramaniam.
Proceedings of the ACM International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS 2011), pages 221-232, San Jose, CA, June 2011. (26/177 = 14% accepted).
Also, Technical Report arXiv:1103.3099, March 2011.
Abstract     Paper     Tech. Report


jsa'11 A Comprehensive Study of Energy Efficiency and Performance of Flash-based SSDs.
Seonyeong Park, Youngjae Kim, Bhuvan Urgaonkar, Joonwon Lee, and Euiseong Seo.
Elsevier Journal of System Architecture (JSA'11), Volume 57, Issue 4, Pages 354-365, April 2011.
Among 25 most downloaded JSA papers in 2011
Abstract     Article    


fast'11 Leveraging Value Locality in Optimizing NAND Flash-based SSDs.
Aayush Gupta, Raghav Pisolkar, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the USENIX Conference on File and Storage Technologies (FAST 2011), pages 91-103, San Jose, CA, February 2011. (20/74 = 27%)
Abstract     Paper    


pmc'11 Provisioning Bandwidth in Directional Antenna-based Wireless Networks.
Shiva Kasiviswanathan, Bo Zhao, Sudarshan Vasudevan, and Bhuvan Urgaonkar.
Elsevier Pervasive and Mobile Computing Journal (PMC), 7(1):114-127, February 2011 (Special section on hot topics in computer networks).
Extends our ICDCN 2010 paper.

Chosen for fast track publication
Abstract    Article


middleware'10 Middleware for a Re-configurable Distributed Archival Store Based on Secret Sharing.
Shiva Chaitanya, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the ACM/IFIP/USENIX Eleventh International Middleware Conference (MIDDLEWARE 2010), pages 107-127, Bangalore, India, Nov-Dec 2010. (16/119 = 17% accepted).
Abstract     Paper     Tech. Report


tc'10 Power Consumption Prediction and Power-Aware Packing in Consolidated Environments.
Jeonghwan Choi, Sriram Govindan, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
IEEE Transactions on Computers (TC), Vol. 59, Issue 12, pages 1640-1654, December 2010.
Extends our MASCOTS 2008 paper.

Abstract    Article


mascots'10 Multi-level Crypto Disk: Seconday Storage with Flexible Performance Versus Security Trade-offs.
Shiva Chaitanya, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Poster in Proceedings of Eighteenth Annual Meeting of the IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS 2010), pages 434-436, Miami Beach, FL, August 2010.
Extended Abstract     Tech. Report


cloud'10 Cloud Computing: A Digital Libraries Perspective.
Pradeep Teregowda, Bhuvan Urgaonkar, and C. Lee Giles.
Proceedings of the IEEE Third International Conference on Cloud Computing (CLOUD 2010), pages 115-122, Miami, FL, July 2010. (20% accepted).
Abstract     Paper


hotcloud'10 CiteSeerX: A Cloud Perspective.
Pradeep Teregowda, Bhuvan Urgaonkar, and C. Lee Giles.
Proceedings of the Second USENIX Workshop on Hot Topics in Cloud Computing (HOTCLOUD 2010), Boston, MA, June 2010. (24% accepted).
Abstract     Paper


icdcn'10 Bandwidth Provisioning in Infrastructure-based Wireless Networks Employing Directional Antennas.
Shiva Kasiviswanathan, Bo Zhao, Sudarshan Vasudevan, and Bhuvan Urgaonkar.
Proceedings of the Eleventh International Conference on Distributed Computing and Networking (ICDCN 2010), pages 295-306, Kolkata, India, January 2010. (22% accepted).
Fast tracked for publication in Elsevier PMC journal
Technical Report CSE-07-008, Department of Computer Science and Engineering, The Pennsylvania State University, July 2007.
Abstract     Tech. Report    Paper


simul'09 FlashSim: A Simulator for NAND Flash-based Solid-State Drives.
Youngjae Kim, Brendan Taurus, Aayush Gupta, and Bhuvan Urgaonkar.
Proceedings of the First International Conference on Advances in System Simulation (SIMUL 2009), Porto, Portugal, September 2009. (31% accepted).
Also, Technical Report CSE-09-008, Department of Computer Science and Engineering, The Pennsylvania State University, May 2009.
Abstract     Paper     Tech. Report


tc'09 Xen and Co.: Communication-aware CPU Management in Consolidated Xen-based Hosting Platforms.
Sriram Govindan, Jeonghwan Choi, Arjun R Nath, Amitayu Das, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
IEEE Transactions on Computers (TC), Vol. 58, No. 8, pages 1111-1125.
Extends our VEE 2007 paper.

Abstract     Article


usenix'09 vPath: Precise Discovery of Request Processing Paths from Black-Box Observations of Thread and Network Activities.
Byung Chul Tak, Chunqiang Tang, Chun Zhang, Sriram Govindan, Bhuvan Urgaonkar, and Rong N. Chang.
Proceedings of the Thirty Fourth USENIX Annual Technical Conference (USENIX 2009), San Diego, CA, June 2009. (32/191 = 17% accepted).
Abstract     Paper


eurosys'09 Statistical Profiling-based Techniques for Effective Power Provisioning in Data Centers.
Sriram Govindan, Jeonghwan Choi, Bhuvan Urgaonkar, Anand Sivasubramaniam, and Andrea Baldini.
Proceedings of EuroSys, sponsored by the European Chapter of ACM SIGOPS (EUROSYS 2009), pages 317-330, Munich, Germany, April 2009. (25/148 = 17% accepted).
Also, Technical Report CSE-08-006, Department of Computer Science and Engineering, The Pennsylvania State University, February 2008.
Abstract     Paper


asplos'09 DFTL: A Flash Translation Layer Employing Demand-based Selective Caching of Page-level Address Mappings.
Aayush Gupta, Youngjae Kim, and Bhuvan Urgaonkar.
Proceedings of the Fourteenth International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2009), pages 229-240, Washington DC, March 2009. (29/113 = 25% accepted).
Also, Technical Report CSE-08-012, Department of Computer Science and Engineering, The Pennsylvania State University, July 2008.
Abstract     Paper     Tech. Report


toit'09 Resource Overbooking and Application Profiling in a Shared Internet Hosting Platform.
Bhuvan Urgaonkar, Prashant Shenoy, and Timothy Roscoe.
ACM Transations on Internet Technologies (TOIT), Vol. 9, No. 1, Article 1, pages 1-45, February 2009.
Extends our OSDI 2002 paper.

Abstract    Article


hotpower'08 An Empirical Analysis of the Energy Efficiency of Flash-based SSDs.
Euiseong Seo, Seonyeong Park, Bhuvan Urgaonkar.
Proceedings of the First Workshop on Power-Aware Computing and Systems (HOTPOWER 2008), co-located with USENIX OSDI 2008, San Diego, CA, December 2008.
Abstract     Paper


mascots'08 Profiling, Prediction, and Capping of Power in Consolidated Environments.
Jeonghwan Choi, Sriram Govindan, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the Sixteenth Annual Meeting of the IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS 2008), pages 3-12, Baltimore, MD, September 2008. (36/94 = 38% accepted).
Also, Technical Report CSE-08-006, Department of Computer Science and Engineering, The Pennsylvania State University, April 2008.

Best Student Paper Award
Abstract     Paper    Tech. Report


jnca'08 Cataclysm: Scalable Overload Policing for Internet Applications.
Bhuvan Urgaonkar and Prashant Shenoy.
Elsevier Journal of Network and Computer Applications (JNCA), 31, pages 891-920, July 2008.
Extends our WWW 2005 paper.

Abstract    Article


sdmas'08 Predicting Web Cache Behavior Using Stochastic State-Space Models.
Amitayu Das, Ritendra Datta, Anand Sivasubramaniam, and Bhuvan Urgaonkar.
Proceedings of the Second International Workshop on Scalable Data Management Applications and Systems (SDMAS 2008), pages 609-616, Las Vegas, NV, July 2008. (29% accepted).
Also, Technical Report CSE-06-018, Department of Computer Science and Engineering, The Pennsylvania State University, October 2006.

Abstract     Paper     Tech. Report   


hpdc'08 Evaluating the Usefulness of Content-Addressable Storage for High-Performance Data-Intensive Applications.
Partho Nath, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the ACM/IEEE International Symposium on High Performance Distributed Computing (HPDC 2008), pages 35-44, Boston, MA, June 2008. (17% accepted).
Abstract     Paper


sigmetrics'08 QDSL: A Queueing Model for Systems with Differential Service Levels.
Shiva Chaitanya, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the ACM International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS 2008), pages 289-300, Annapolis, MD, June 2008. (36/201 = 18% accepted).
Abstract     Paper


wisec'08 Towards Event Source Unobservability with Minimum Network Traffic in Sensor Networks.
Yi Yang, Min Shao, Sencun Zhu, Bhuvan Urgaonkar, and Guohong Cao.
Proceedings of the First ACM Confrence on Wireless Network Security (WISEC 2008), March-April 2008, pages 77-88, Alexandria, VA. (16/96 = 17% accepted).
Abstract     Paper


taas'08 Agile Dynamic Provisioning of Multi-tier Internet Applications.
Bhuvan Urgaonkar, Prashant Shenoy, Abhishek Chandra, Pawan Goyal, and Timothy Wood.
ACM Transactions on Adaptive and Autonomous Systems (TAAS), Vol. 3, No. 1, pages 1-39, March 2008.
Extends our ICAC 2005 paper.

Abstract    Article


ijfcs'07 Application Placement on a Cluster of Servers.
Bhuvan Urgaonkar, Arnold Rosenberg, and Prashant Shenoy.
International Journal on Foundations of Computer Science (IJFCS), Vol. 18, No. 5, pages 1023-1041, October 2007.
Extends our PDCS 2004 paper.

Abstract    Article


vee'07 Xen and Co.: Communication-aware CPU Scheduling for Consolidated Xen-based Hosting Platforms.
Sriram Govindan, Arjun R. Nath, Amitayu Das, Bhuvan Urgaonkar, and Anand Sivasubramaniam.
Proceedings of the Third International ACM SIGPLAN/SIGOPS Conference on Virtual Execution Environments (VEE 2007), pages 126-136, San Diego, CA, June 2007. (19/70 = 27% accepted).
Also, Technical Report CSE-06-017, Department of Computer Science and Engineering, The Pennsylvania State University, October 2006.
Abstract     Paper     Tech. Report    Talk


spaa'07 Packing to Angles and Sectors.
Piotr Berman, Jieun Jeong, Shiva Kasiviswanathan, and Bhuvan Urgaonkar.
Proceedings of the Nineteenth ACM Symposium on Parallel Algorithms and Architectures (SPAA 2007), pages 171-180, San Diego, CA, June 2007. (37/130 = 28% accepted).
Also, Electronic Colloquium on Computational Complexity Report TR06-030, 2006.
Abstract    Paper     Tech. Report    


tweb'07 Analytic Modeling of Multi-tier Internet Services and its Applications.
Bhuvan Urgaonkar, Giovanni Pacifici, Prashant Shenoy, Mike Spreitzer, and Asser Tantawi.
ACM Transactions on the Web (TWEB 2007), Vol. 1, No. 1, Pages 1-35, May 2007.
Extends our Sigmetrics 2005 paper.

Abstract    Article    


ccr'06 Dynamic Cache Reconfiguration Strategies for a Cluster-based Streaming Proxy.
Yang Guo, Zihui Ge, Bhuvan Urgaonkar, Prashant Shenoy, and Don Towsley.
Elsevier Computer Communications Review (CCR), Vol. 29, Issue 10, Pages 1710-1721, June 2006.
Extends our WCW 2003 paper.

Abstract    Article


thesis'05 Dynamic Resource Management in Internet Hosting Platforms.
Bhuvan Urgaonkar.
Ph.D. Thesis, Department of Computer Science, University of Massachusetts Amherst, September 2005.
Thesis


icac'05 Dynamic Provisioning of Multi-tier Internet Applications.
Bhuvan Urgaonkar, Prashant Shenoy, Abhishek Chandra, and Pawan Goyal.
Proceedings of the 2nd IEEE International Conference on Autonomic Computing (ICAC 2005), pages 217-228, Seattle, June 2005. (25/150 = 16% accepted).
Also, Technical Report TR04-100, Department of Computer Science, University of Massachusetts Amherst, October 2004.
Best Student Paper Award
Abstract    PDF     Tech. Report     Talk


sigmetrics'05 An Analytical Model for Multi-tier Internet Services and its Applications.
Bhuvan Urgaonkar, Giovanni Pacifici, Prashant Shenoy, Mike Spreitzer, and Asser Tantawi.
Proceedings of the ACM International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS 2005), pages 291-302, Banff, Canada, June 2005. (31/237 = 13% accepted).
Also, Technical Report TR04-99, Department of Computer Science, University of Massachusetts Amherst, October 2004.
Abstract    Paper     Tech. Report     Talk


www'05 Cataclysm: Handling Extreme Overloads in Internet Applications.
Bhuvan Urgaonkar and Prashant Shenoy.
Proceedings of the Fourteenth International World Wide Web Conference (WWW 2005), pages 740-749, Chiba, Japan, May 2005. (77/550 = 14% accepted).
Also, Brief Announcement in the Proceedings of the Twenty-Third Annual ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing (PODC), page 290, July 25-28, 2004, St. John's, Newfoundland, Canada.
Also, Technical Report TR03-40, Department of Computer Science, University of Massachusetts Amherst, Dec. 2003.
Abstract    Paper     Brief Announcement    Tech. Report (July 2004)     Talk


pdcs'04 Application Placement on a Cluster of Servers.
Bhuvan Urgaonkar, Arnold Rosenberg, and Prashant Shenoy.
Proceedings of the Seventeenth International Conference on Parallel and Distributed Computing Systems (PDCS 2004), pages 85-90, San Fransisco, CA, September 2004. (62/185 = 33% accepted).
Also, Technical Report TR04-18, Department of Computer Science, University of Massachusetts Amherst, April 2004.
Abstract    Tech. Report    Paper


tpds'04 Sharc: Managing CPU and Network Bandwidth in Shared Clusters.
Bhuvan Urgaonkar and Prashant Shenoy.
IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 15, No. 1., pages 2-17, January 2004.
Also, Technical Report TR01-08, Department of Computer Science, University of Massachusetts Amherst, March 2001. Revised October 2001.
Abstract     Article    Tech. Report (PS)


wcw'03 On Dynamic Cache Reconfiguration Strategies for a Cluster-based Streaming Proxy.
Yang Guo, Zihui Ge, Bhuvan Urgaonkar, Prashant Shenoy, and Don Towsley.
Proceedings of the Eighth International Workshop on Web Content Caching and Distribution, September 2003.
Also, Technical Report TR03-34, Department of Computer Science, Univesity of Massachusetts Amherst, July 2003.
Abstract     Paper    Tech. Report


osdi'02 Resource Overbooking and Application Profiling in Shared Hosting Platforms.
Bhuvan Urgaonkar, Prashant Shenoy, and Timothy Roscoe.
Proceedings of the Fifth USENIX Symposium on Operating Systems Design and Implementation (OSDI 2002), pages 239-254, Boston, MA, December 2002. (28/150 = 18% accepted).
Also, Technical Report TR02-21, Department of Computer Science, University of Massachusetts Amherst.
Abstract   Paper     Talk


icdcs'01 Maintaining Mutual Consistency for Cached Web Objects.
Bhuvan Urgaonkar, Anoop Ninan, Mohammad Raunak, Prashant Shenoy, and Krithi Ramamritham.
Proceedings of the Twenty First International Conference on Distributed Computing Systems (ICDCS 2001), pages 371-380, Phoenix, AZ, April 2001. (69/217 = 31% accepted).
Also, Technical Report TR00-47, Department of Computer Science, University of Massachusetts Amherst, September 2000.
Abstract     Paper    Tech. Report (PS)     Talk