Dong Xuan’s Research Publications

Newly Accepted Journals

Wei Yu, Xun Wang, Prasad Calyam, Dong Xuan and Wei Zhao, Camouflaging Worm: Modeling and Detection, to appear in IEEE Transactions on Dependable and Secure Computing (TDSC), accepted in Nov. 2009.
Changqing Xu, Xiaole Bai, Lei Ding, Jin Teng, Sriram Chellappan and Dong Xuan, Directed-Coverage in Wireless Sensor Networks: Concept and Quality, to appear in Ad Hoc & Sensor Wireless Networks (AHSWN), accepted in Nov. 2009.
Ziqiu Yun, Xiaole Bai, Dong Xuan, Ten H. Lai and Weijia Jia, Optimal Deployment Patterns for Full Coverage and k-Connectivity (k<=6) Wireless Sensor Networks, to appear in ACM/IEEE Transactions on Networking (ToN), accepted in Sept. 2009.
Xiaole Bai, Ziqiu Yun, Dong Xuan, Ten H. Lai and Weijia Jia, Optimal Deployment Patterns for Four-Connectivity And Full-Coverage Wireless Sensor Networks, to appear in IEEE Transactions on Mobile Computing (TMC), accepted in Aug. 2009.
Ai Chen, Ten H. Lai and Dong Xuan, Measuring and Guaranteeing Quality of Barrier-Coverage for General Belts with Wireless Sensors, to appear in ACM Transactions on Sensor Networks (TOSN), accepted in June 2009.
Wenjun Gu, Zhimin Yang, Dong Xuan, Weijia Jia and Can Que, Null Data Frame: A Double-edged Sword in IEEE 802.11 WLANs, to appear in IEEE Transactions on Distributed and Parallel Systems (TPDS), accepted in June 2009.

2010

Boxuan Gu, Xiaole Bai, Zhimin Yang, Adam Champion and Dong Xuan, Malicious Shellcode Detection with a Virtual Memory Snapshot, accepted to appear in Proc. of IEEE International Conference on Computer Communications (INFOCOM), March 2010.
Xiaole Bai, Ziqiu Yun, Dong Xuan, Weijia Jia and Wei Zhao, Pattern Mutation in Wireless Sensor Deployment, accepted to appear in Proc. of IEEE International Conference on Computer Communications (INFOCOM), March 2010.
Thang Le, Prasun Sinha and Dong Xuan, Turning Heterogeneity into An Advantage in Wireless Ad-hoc Network Routing, in Ad Hoc Networks Journal, Elsevier, Vol. 8, No. 1, Jan. 2010, pp. 108-118.

2009

Zheng Ling, Junzhou Luo, Wei Yu, Xinwen Fu, Dong Xuan and Weijia Jia, A New Cell Counter Based Attack against Tor, in Proc. of ACM Conference on Computer and Communications Security (CCS), Nov. 2009.
Xiaole Bai, Lei Ding, Jin Teng, Sriram Chellappan, Changqing Xu and Dong Xuan, Directed Coverage in Wireless Sensor Networks: Concept and Quality, in Proc. of IEEE Mobile and Ad-hoc Sensor Systems (MASS), Oct. 2009
Xudong Ni, Zhimin Yang, Xiaole Bai, Adam Champion and Dong Xuan, DiffUser: Differentiated User Access Control on Smartphone, accepted in Proc. of International Workshop on Wireless and Sensor Networks Security (WSNS'09) conjunction with IEEE Mobile and Ad-hoc Sensor Systems (MASS), Oct. 2009
Wei Yu, Xun Wang, Xinwen Fu, Dong Xuan and Wei Zhao, An Invisible Localization Attack to Internet Threat Monitors, in IEEE Transactions on Distributed and Parallel Systems (TPDS), Vol. 20, No. 11, Nov. 2009, pp. 1611-1625.
Xiaole Bai, Chuanlin Zhang, Dong Xuan, Jin Teng and Weijia Jia, Low-Connectivity and Full-Coverage Three Dimensional Networks, in Proc. of ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), May 2009.
Xiaole Bai, Chuanlin Zhang, Dong Xuan and Weijia Jia, Full-Coverage and K-Connectivity (K=14, 6) Three Dimensional Networks, in Proc. of IEEE International Conference on Computer Communications (INFOCOM), April 2009.
Weijia Jia, Fung Po Tso, Zhen Ling, Xinwen Fu, Dong Xuan and Wei Yu, Blind Detection of Spread Spectrum Flow Watermarks, in Proc. of IEEE International Conference on Computer Communications (INFOCOM), April 2009.
Jin Teng, Changqing Xu, Weijia Jia and Dong Xuan, D-Scan: Enabling Fast and Smooth Handoff in AP-dense 802.11 Wireless Networks, in the mini-conference conjunction with IEEE International Conference on Computer Communications (INFOCOM), April 2009.
Nan Xu, Fan Zhang, Yisha Luo, Weijia Jia, Dong Xuan and Jin Teng, Stealthy Video Capturer: A New Video-based Spyware in 3G Smartphones, in Proc. of ACM Conference on Wireless Network Security (WiSec), March 2009.
Zhimin Yang, Boxuan Gu, Adam Champion, Xiaole Bai and Dong Xuan, Link-Layer Protection in 802.11i WLANs with Dummy Authentication, in Proc. of ACM Conference on Wireless Network Security (WiSec), March 2009 (short paper).

2008

Wei Yu, Sriram Chellappan, Xun Wang and Dong Xuan, Peer-to-Peer System-based Active Worm Attacks: Modeling, Analysis and Defense, in Journal of Computer Communications (COMCOM), Elsevier, Vol. 31, No. 17, Nov. 2008, pp. 4005-4017.
Xiaole Bai, Wenjun Gu, Sriram Chellappan, Xun Wang, Dong Xuan and Bin Ma, PAS: Predicate-based Authentication Services Against Powerful Passive Adversaries, in Proc. of Annual Computer Security Applications Conference (ACSAC), Dec. 2008.
Wenjun Gu, Zhimin Yang, Can Que, Dong Xuan and Weijia Jia, On Security Vulnerabilities of Null Data Frames in IEEE 802.11 based WLANs, in Proc. of IEEE International Conference on Distributed Computing Systems (ICDCS), June 2008, pp. 28-35.
Xiaole Bai, Dong Xuan, Ziqiu Yun, Ten H. Lai and Weijia Jia, Complete Optimal Deployment Patterns for Full-Coverage and k-Connectivity (k <=6) Wireless Sensor Networks, in Proc. of ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), May 2008, pp. 401-410.
Ai Chen, Ten H. Lai and Dong Xuan, Measuring and Guaranteeing Quality of Barrier-Coverage in Wireless Sensor Networks, in Proc. of ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), May 2008, pp. 421-430.
Xiaole Bai, Ziqiu Yun, Dong Xuan, Ten H. Lai and Weijia Jia, Deploying Four-Connectivity And Full-Coverage Wireless Sensor Networks, in Proc. of IEEE International Conference on Computer Communications (INFOCOM), April 2008, pp. 906-914.
Xun Wang, Wei Yu, Xinwen Fu, Dong Xuan and Wei Zhao, iLOC: An invisible LOCalization Attack to Internet Threat Monitoring System, in the mini-conference conjunction with IEEE International Conference on Computer Communications (INFOCOM), April 2008, pp. 1930-1938.

2007

Wenjun Gu, Xiaole Bai, Sriram Chellappan, Dong Xuan and Weijia Jia, Network Decoupling: A Methodology for Secure Communications in Wireless Sensor Networks, in IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 18, No. 12, Dec. 2007, pp. 1784-1796.
Sriram Chellappan, Wenjun Gu, Xiaole Bai, Dong Xuan, Bin Ma and Kaizhong Zhang, Deploying Wireless Sensor Networks under Limited Mobility Constraints, in IEEE Transactions on Mobile Computing (TMC), Vol. 6, No. 10, Oct. 2007, pp. 1142-1157.
Xun Wang, Wei Yu, Adam Champion, Xinwen Fu and Dong Xuan, Detecting Worms via Mining Dynamic Program Execution, in Proc. of IEEE International Conference on Security and Privacy in Communication Networks (SecureComm), Sept. 2007, pp. 412-421.
Wei Yu, Xinwen Fu, Steve Graham, Dong Xuan and Wei Zhao, DSSS-Based Flow Marking Technique for Invisible Traceback, in Proc. of IEEE Symposium on Security and Privacy (Oakland), May. 2007, pp. 18-32.
Zhimin Yang, Eylem Ekici and Dong Xuan, A Localization-Based Anti-Sensor Network System, in Proc of the mini-conference in conjunction with IEEE International Conference on Computer Communications (INFOCOM), May 2007, pp. 6-12.

2006

Sriram Chellappan, Xiaole Bai, Bin Ma, Dong Xuan and Changqing Xu, Mobility Limited Flip-based Sensor Network Deployment, in IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 18, No. 2, Oct. 2006, pp. 199-211.

Li Xiao, Yunhao Liu, Wenjun Gu, Dong Xuan and Xiaomei Liu, Mutual Anonymous Overlay Multicast, in Journal of Parallel and Distributed Computing (JPDC), Elsevier, Vol. 66, No. 9, Sept. 2006, pp. 1205-1216.

Wei Yu, Xun Wang, Dong Xuan and David Lee, Effective Detection of Active Worms with Varying Scan Rate, in Proc. of IEEE International Conference on Security and Privacy in Communication Networks (SecureComm), Aug. 2006 (10 pages).
Wei Yu, Xun Wang, Prasad Calyam, Dong Xuan and Wei Zhao, On Detecting Camouflaging Worm, in Proc. of Annual Computer Security Applications Conference (ACSAC), Aug. 2006, pp. 235-244.
Wei Yu, Sriram Chellappan, Dong Xuan and Wei Zhao, Distributed Policy Processing in Active-Service based Infrastructures, in International Journal of Communication Systems (IJCS), John Wiley & Sons, Vol. 19, No. 7, July 2006, pp. 727-750.
Xun Wang, Sriram Chellappan, Philip Corey Boyer and Dong Xuan, On the Effectiveness of Secure Overlay Forwarding Systems under Intelligent Distributed DoS Attacks, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 17, No. 7, June 2006, pp. 619-632.
Wenjun Gu, Xiaole Bai, Sriram Chellappan and Dong Xuan, Network Decoupling for Secure Communications in Sensor Networks, in Proc. of IEEE International Workshop on Quality of Service (IWQoS), June 2006, pp. 189-198 (slides).
Wei Yu, Thang Nam Le, Jangwon Lee and Dong Xuan, Effective Query Aggregation for Data Services in Sensor Networks, in International Journal of Computer Communications (JCC), Elsevier, Vol. 29, No. 18, June 2006, pp. 3733-3744.
Xiaole Bai, Santosh Kumar, Dong Xuan, Ziqiu Yun and Ten H. Lai, Deploying Wireless Sensors to Achieve Both Coverage and Connectivity, in Proc. of ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), May 2006, pp. 131-142 (slides).
Thang Nam Le, Wei Yu, Xiaole Bai and Dong Xuan, A Dynamic GHT for Data-Centric Storage in Sensor Networks, in Proc. of IEEE Wireless Communications and Networking Conference (WCNC), April 2006 (7 pages).
Xun Wang, Sriram Chellappan, Wenjun Gu, Wei Yu and Dong Xuan, Policy-driven Physical Attacks in Sensor Networks: Modeling and Measurement, in Proc. of IEEE Wireless Communications and Networking Conference (WCNC), April 2006 (8 pages).
Li Xiao, Yunhao Liu, Wenjun Gu, Dong Xuan and Xiaomei Liu, A Design of Overlay Anonymous Multicast Protocol, in Proc. of IEEE International Parallel & Distributed Processing Symposium (IPDPS), April 2006 (10 pages).

Shengquan Wang, Zhibin Mai, Dong Xuan and Wei Zhao, Design and Implementation of QoS-Provisioning System for Voice over IP, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 17, No. 3, March 2006, pp. 276-288.

Xun Wang, Wenjun Gu, Kurt Schosek, Sriram Chellappan and Dong Xuan, Sensor Network Configuration under Physical Attacks, accepted to appear in International Journal of Ad Hoc and Ubiquitous Computing (IJAHUC), Inderscience, Jan. 2006.

2005

Sriram Chellappan, Xiaole Bai, Bin Ma and Dong Xuan, Sensor Network Deployment using Flip-based Sensors, in Proc. of IEEE Mobile Sensor and Ad-hoc and Sensor Systems (MASS), Nov. 2005, pp. 291-298 (slides).
Wenjun Gu, Xun Wang, Sriram Chellappan, Dong Xuan and Ten H. Lai, Defending against Search-based Physical Attacks in Sensor Networks, in Proc. of IEEE Mobile Sensor and Ad-hoc and Sensor Systems (MASS), Nov. 2005, pp. 520-527 (slides).
Thang Nam Le, Wei Yu and Dong Xuan, An Adaptive Zone-Based Storage Architecture for Wireless Sensor Networks, in Proc. of Global Telecommunications Conference (GLOBECOM), Nov. 2005, pp. 2782-2786.
Wei Yu, Sriram Chellappan and Dong Xuan, On Defending Peer-to-Peer System-based Active Worm Attack, in Proc. of IEEE Global Telecommunications Conference (GLOBECOM), Nov. 2005, pp. 1757-1761.
Xun Wang, Sriram Chellappan, Wenjun Gu, Wei Yu and Dong Xuan, Search-based Physical Attacks in Sensor Networks, in Proc. of IEEE International Conference on Computer Communication and Networks (ICCCN), Oct. 2005, pp. 489-496.
Xun Wang, Wenjun Gu, Kurt Schosek, Sriram Chellappan and Dong Xuan, Sensor Network Configuration under Physical Attacks, Proc. of IEEE International Conference on Computer Networks and Mobile Computing (ICCNMC), Aug. 2005, pp. 23-32.
Xun Wang, Wenjun Gu, Kurt Schosek, Sriram Chellappan and Dong Xuan, Lifetime Optimization of Sensor Networks under Physical Attacks, in Proc of IEEE International Conference on Communications (ICC), May 2005, pp. 3295-3301.
Wei Yu, Philip Coyer Boyer, Sriram Chellappan and Dong Xuan, Peer-to-Peer System-based Active Worm Attacks: Modeling and Analysis, in Proc. of IEEE International Conference on Communications (ICC), May 2005, pp. 295-300.

Shengquan Wang, Dong Xuan and Wei Zhao, Analyzing and Enhancing the Resilience of Structured Peer-to-Peer Systems, Journal of Parallel and Distributed Computing (JPDC), Elsevier, Vol. 65, Jan. 2005, pp. 207-219.

Wei Yu, Sriram Challappan and Dong Xuan, P2P/ Grid-based Overlay Architecture to Support VoIP Services in Large Scale IP Networks, in Journal of Future Generation Computer Systems (FGCS), Elsevier, Vol. 21, No. 1, Jan. 2005, pp. 209-219.

2004

Wei Yu, Thang Nam Le, Dong Xuan and Wei Zhao, Query Aggregation for Providing Efficient Data Services in Sensor Networks, in Proc. of IEEE Mobile and Ad-hoc Sensor Systems (MASS), Oct. 2004, pp. 31-40.

Weijia Jia, Dong Xuan, Wanqing Tu, Lidong Lin and Wei Zhao, Distributed Admission Control for Anycast Flows, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol 15, No. 8, Aug. 2004, pp. 673-686.

Xinwen Fu, Bryan Graham, Dong Xuan, Riccard Bettati and Wei Zhao, Empirical and Theoretical Evaluation of Active Probing Attacks and Their Countermeasures, in Proc. of Information Hiding Workshop (IH), May 2004, pp. 266-281.

Shengquan Wang, Dong Xuan, Riccardo Bettati and Wei Zhao, Providing Absolute Differentiated Services for Real-Time Applications in Static-Priority Scheduling Networks, IEEE/ACM Transactions on Networking (ToN), Vol 12, No. 2, April 2004, pp. 326-339.

Dong Xuan, Sriram Chellappan, Xun Wang and Shengquan Wang, Analyzing the Secure Overlay Services Architecture under Intelligent DDoS Attacks, in Proc. of IEEE International Conference on Distributed Computing Systems (ICDCS), Mar. 2004, pp. 408-417 (slides).

Dong Xuan, Sriram Chellappan and Xun Wang, Resilience of Structured Peer-to-Peer Systems: Analysis and Enhancement, in Handbook on Theoretical and Algorithmic Aspects of Sensor, Ad Hoc Wireless and Peer-to-Peer Networks, edited by Jie Wu, CRC press LLC, 2004.

2003

Shengquan Wang, Dong Xuan and Wei Zhao, On Resilience of Structured Peer-to-Peer Systems, in Proc. of IEEE Global Telecommunications Conference (GLOBECOM), Dec. 2003, pp. 3851-3856.
Dong Xuan, Sriram Chellappan and Muralidhar Krishnamoorthy, RChord: An Enhanced Chord System Resilient to Routing Attacks, in Proc. of IEEE International Conference on Computer Networks and Mobile Computing (ICCNMC), Oct. 2003, pp. 69-77.
Xinwen Fu, Bryan Graham, Riccardo Bettati, Wei Zhao and Dong Xuan, Analytical and Empirical Analysis of Countermeasures to Traffic Analysis Attacks, in Proc. of International Conference on Parallel Processing (ICPP), Oct. 2003, pp. 483-492.
Xiuzhong Chen, Chunfeng Wang, Dong Xuan, Zhongcheng Li, Yinghua Min and Wei Zhao, Survey on QoS Management of VoIP, in Proc. of IEEE International Conference on Computer Networks and Mobile Computing (ICCNMC), Oct. 2003, pp. 253-259.
Wei Yu, Dong Xuan, Sandeep K. Reddy, Riccardo Bettati and Wei Zhao, Distributed Policy Processing in Virtual Private Operation Environment for Large Scale Networks, in Proc. of IEEE Systems, Man and Cybernetics Society Information Assurance Workshop (IAW), June 2003, pp. 84-91.
Shengquan Wang, Dong Xuan, Riccardo Bettati and Wei Zhao, A Study of Providing Statistical QoS Guarantees in Differentiated Services Networks, in Proc. of IEEE International Symposium on Network Computing and Applications (NCA), April 2003, pp. 297-304.
Zhibin Mai, Shengquan Wang, Dong Xuan and Wei Zhao, Group Aggregation for Scalable Anycast Routing, in Proc. of IEEE International Performance Computing and Communications Conference (IPCCC), April 2003, pp. 33-40.

Byung-Kyu Choi, Dong Xuan, Chengzhi Li, Riccardo Bettati and Wei Zhao, Utilization-based Admission Control for Real-Time Communication, Journal of Real-Time Systems (JRTS), Vol. 24, No.2, 2003, pp. 171-202.

2002

Shengquang Wang, Zhibin Mai, Walt Magnussen, Dong Xuan and Wei Zhao, Implementation of QoS-Provision System for Voice over IP, in Proc. of IEEE Real-time Technology and Applications Symposium (RTAS), Oct. 2002, pp. 266-275.
Wei Yu, Dong Xuan and Wei Zhao, Middleware based Approach for Preventing Distributed Denial of Service Attacks, in Proc. of IEEE Military Communications (MILCOM), Oct. 2002, pp. 1124-1129.

Dong Xuan, Shengquan Wang, Ye Zhu, Riccardo Bettati and Wei Zhao, A Gateway-Based Defense System for Distributed Denial-of-Service Attacks in High Speed Networks, accepted to appear in IEEE Transaction on Systems, Man, and Cybernetics (TSMC), 2002.

Wei Yu, Dong Xuan, Riccardo Bettati, and Wei Zhao, An Integrated Middleware-Based Solution for Supporting Secured Dynamic-Coalition Applications in Heterogeneous Environments, accepted to appear in IEEE Transaction on Systems, Man, and Cybernetics (TSMC), 2002.

2001

Shengquan Wang, Dong Xuan, Riccardo Bettati and Wei Zhao, Differentiated Services with Statistical Real-Time Guarantees in Static-Priority Scheduling Networks, in Proc. of IEEE Real-Time System Symposium (RTSS), Nov. 2001, pp. 289-298.
Yong Guan, Xingwen Fu, Dong Xuan, Prashanth Umesh Shenoy, Riccardo Bettati and Wei Zhao, NetCamo: Camouflaging Network Traffic for QoS-Guaranteed Mission Critical Applications, IEEE Transactions on Systems, Man, and Cybernetics (TSMC), Vol. 31, No. 4, July 2001, pp. 253-265
Dong Xuan, Riccardo Bettati, and Wei Zhao, A Gateway-Based Defense System for Distributed DoS Attacks in High Speed Networks, in Proc. of IEEE Systems, Man, and Cybernetics Information Assurance Workshop (IAW), June 2001, pp. 212-219.
Wei Yu, Dong Xuan, Bryan Graham, S. Santhanam, Riccardo Bettati, and Wei Zhao, An Integrated Middleware-Based Solution for Supporting Secured Dynamic-Coalition Applications in Heterogeneous Environments, in Proc. of IEEE Systems, Man, and Cybernetics Information Assurance Workshop (IAW), June 2001, pp. 259-264.
Dong Xuan and Weijia Jia, Distributed Admission Control for Anycast Flows with QoS Requirements, in Proc. of IEEE International Conference on Distributed Computing Systems (ICDCS), April 2001, pp. 292-300.
Shengquan Wang, Dong Xuan, Riccardo Bettati and Wei Zhao, Providing Absolute Differentiated Services for Real-Time Applications in Static Priority Scheduling Networks, in Proc. of IEEE International Conference on Computer Communications (INFOCOM), April 2001, pp. 669-678.

2000

Dong Xuan, Chengzhi Li, Riccardo Bettati, Jianer Chen and Wei Zhao, Utilization-based Admission Control for Real-Time Applications, in Proc. of International Conference on Parallel Processing (ICPP), Aug. 2000, pp. 251-260.

Dong Xuan, Weijia Jia, Wei Zhao and Hongwen Zhu, A Routing Protocol for Anycast Messages, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 11, No. 6, June 2000, pp. 571-588.

Byung-Kyu Choi, Dong Xuan, Chengzhi Li, Riccardo Bettati and Wei Zhao, Scalable QoS Guaranteed Communication Services for Real-Time Applications, in Proc. of IEEE International Conference on Distributed Computing Systems (ICDCS), April 2000, pp. 180-187.

Weijia Jia, Dong Xuan and Wei Zhao, Integrated Routing Algorithms for Anycast Messages, IEEE Communication Magazine, Vol. 38, No. 1, Jan. 2000, pp. 48-53.

1999

Weijia Jia, Wei Zhao, Dong Xuan and Gaochao Xu, An Efficient Fault-Tolerant Multicast Routing Protocol with Core-Based Tree Techniques, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol.10, No.10, Oct.1999, pp. 984-1000.
Yong Guan, Chengzhi Li, Dong Xuan, Riccardo Bettati and Wei Zhao, Preventing traffic analysis for real-time communication networks, in Proc. of IEEE Military Communications (MILCOM), Oct. 1999, pp. 744-750.
Weijia Jia, Wei Zhao, Dong Xuan, and Gaochao Xu, An Efficient Fault-Tolerant Multicast Routing Protocol with Core-Based Tree Techniques, in Proc. of International Conference on Parallel Processing (ICPP), Aug. 1999, pp. 508-514.
Weijia Jia, Gaochao Xu, Wei Zhao, and Dong Xuan, An Integrated Routing Protocol for Reliable Anycast and Multicast Communications, in Proc. of International Conference on Parallel and Distributed Computing Systems (ICPDCS), Aug. 1999, pp. 185-190.

1998

Weijia Jia, Dong Xuan and Wei Zhao, Integrated Routing Algorithms for Anycast Messages, in Proc. of IEEE Global Telecommunications Conference (GLOBECOM), Vol: 3, Nov. 1998, pp. 1635-1640.
Dong Xuan, Weijia Jia and Wei Zhao, Routing Algorithms for Anycast Messages, in Proc. of International Conference on Parallel Processing (ICPP), Aug. 1998, pp. 122-130

Acknowledgement

The above work is partially supported by the US National Science Foundation (NSF) CAREER Award CCF0546668, the Army Research Office (ARO) under grant No. AMSRD-ACC-R50521-CI. Any opinions, findings, conclusions, and recommendations in this paper are those of the authors and do not necessarily reflect the views of the funding agencies.

-- Last Updated on 6/1/09