PMRL Publications
Publications
Accordions
62. H. Zhang, T. Liu, U. Gupta, S. B. Isukapatiy, E. Ashik, A. J. Morgan, B. Lee, W. Sung, A. K. Agarwal, and A. Fayed, “A 600V Half-Bridge Power Stage Fully Integrated with 25V Gate-Drivers in SiC CMOS Technology,” 2022 IEEE Int. Midwest Symp. on Circuits and Systems (MWSCAS), Fukuoka, Japan, Aug. 2022, pp. 1-4.
61. E. Ashik, S. Isukapati, H. Zhang, T. Liu, U. Gupta, A. Morgan, V. Misra, W. Sung, A. Fayed, A. Agarwal, B. Lee, “Bias Temperature Instability on SiC n- and p-MOSFETs for High Temperature CMOS Applications,” 2022 IEEE International Reliability Physics Symposium (IRPS), Mar. 2022, pp. 3B.4-1 to 3B.4-8.
60. T. Liu, H. Zhang, S. B. Isukapatiy, E. Ashik, A. J. Morgan, B. Lee, W. Sung, A. Fayed, M. H. White, and A. K. Agarwal, “SPICE Modeling and Circuit Demonstration of a SiC Power IC Technology,” IEEE Journal of the Electron Devices Society, vol. 10, no. 2, pp. 129-138, Feb. 2022.
59. S. B. Isukapati, H. Zhang, T Liu, E. Ashik, B. Lee, A. J. Morgan, W. Sung, A. Fayed, A. K. Agarwal, “Development of Isolated CMOS and HV MOSFET on an N-epi/P-epi/4H-SiC N+ Substrate for Power IC Applications,” 2021 IEEE 8th Workshop on Wide Bandgap Power Devices and Applications (WIPDA), Nov. 2021, pp. 118-122.
58. Tanner Tengberg and Ayman Fayed, “A Dual-Frequency Single-Inductor Single-Output DC-DC Converter Topology with Spur-Free Switching for Security Applications,” 2021 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), East Lansing, Michigan, Aug. 2021, pp. 974-977.
57. T. Liu, H. Zhang, S. B. Isukapatiy, E. Ashik, A. J. Morgan, B. Lee, W. Sung, M. H. White, A. Fayed, and A. K. Agarwal, “SPICE Modeling and CMOS Circuit Development of a SiC Power IC Technology,” 2021 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), East Lansing, Michigan, Aug. 2021, pp. 966-969.
56. S. B. Isukapati, H. Zhang, T Liu, E. Ashik, B. Lee, A. J. Morgan, W. Sung, A. Fayed, A. K. Agarwal, “Monolithic Integration of Lateral HV Power MOSFET with LV CMOS for SiC Power IC Technology,” 2021 IEEE 33rd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Nagoya, Japan, Jun. 2021, pp. 267-270. Recipient of best poster presentation award.
55. M. Singh and A. Fayed, “A 1-A 6-MHz Digitally-Assisted Buck-Boost Converter with Seamless Mode Transitions and Fast Dynamic Performance for Mobile Devices,” IEEE Tran. on Power Electronics, vol. 36, no. 4, pp. 4338-4351, Apr. 2021. Recipient of the 2021 IEEE Tran. on Power Electronics Second Place Prize Paper Award.
54. M. Singh and A. Fayed, “A 2-A 6-MHz Hysteretic Buck Converter with an 8-Bit Digital Jitter-Insensitive Frequency Correction Loop using Dual-Sided Hysteretic Band Modulation,” 2020 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Springfield, MA, Aug. 2020, pp. 754-757.
53. M.S. Ahmed, W. Fu, R. Byrd, and A. Fayed, “A Spur-free, 150-mA Buck Regulator with 96.3% Peak-Efficiency and 77.2% Minimum Efficiency at 10-µA Load for Microcontrollers with Noise-Sensitive ADCs,” 2020 IEEE Applied Power Electronics Conf. (APEC), New Orleans, Louisiana, Mar. 2020, pp. 1298-1301.
52. M. S. Ahmed and A. Fayed, “A Current-Mode Delay-based Hysteretic Buck Regulator with Enhanced Efficiency at Ultra-light loads for Low-Power Microcontrollers,” IEEE Transactions on Power Electronics, vol. 35, no. 1, pp. 471-483, Jan. 2020.
51. M. Singh and A. Fayed, “Imbalanced High-Current Multi-Phase Buck Converters for High-Performance CPUs,” 2019 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Dallas, Texas, Aug. 2019, pp. 929-932.
50. Y. Jiang, S. Asar, M. Ahmed, H. Zhang, and A. Fayed, “Output Control Techniques for Dual-Frequency SIMO Buck Converters,” IEEE Transactions on Circuits & Systems I, vol. 66, no. 10, pp. 4055-4067, Oct. 2019.
49. M. S. Ahmed and A. Fayed, “An All-Passive Emulated Ripple Control Technique For Constant-On-Time Buck Converters In CCM,” 2019 IEEE Int. symposium on circuits and Systems (ISCAS), Sapporo, Japan, May 2019.
48. S. Asar, H. Zhang, and A. Fayed, “Dual-Frequency SIMO Topologies for On-Chip Dynamic Power Supplies,” 2018 IEEE Power Supply on Chip Workshop (PWRSoC), Hsinchu, Taiwan, Oct. 2018. Poster.
47. M. Singh and A. Fayed, “An 8 A 100-MHz 4-Phase Buck Converter with Fast Dynamic Response and Enhanced Light-Load Efficiency,” 2018 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Windsor, Canada, Aug. 2018, pp. 861-864.
46. Y. Jiang, S. Asar, and A. Fayed, “An Average Inductor Current Sensor with Enhanced Accuracy in DCM for Buck Converters,” 2018 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Windsor, Canada, Aug. 2018, pp. 595-598.
45. Y. Jiang, M. Swilam, S. Asar, and A. Fayed, “An Accurate Sense-FET-based Inductor Current Sensor with Wide Sensing Range for Buck Converters,” 2018 IEEE Int. symposium on circuits and Systems (ISCAS), Florence, Italy, May 2018, pp. 1-4.
44. M. Abdelfattah, M. Swilam, B. Dupaix, S. Smith, A. Fayed, and W. Khalil, “An On-Chip Resonant-Gate-Drive Switched-Capacitor Converter for NearThreshold Computing Achieving 70.2% Efficiency at 0.92A/mm2 Current Density and 0.4V Output,” 2018 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, Feb. 2018, pp. 438-440.
43. Mina Nashed and Ayman Fayed, “A Current-Mode Hysteretic Buck Converter with Spur-Free Control for Variable Switching Noise Mitigation,” IEEE Transactions on Power Electronics, vol. 33, no. 1, pp. 650-664, Jan. 2018.
42. Y. Jiang and A. Fayed, “A Buck Converter with Optimized Dynamic Response using Lag-Lead Active Voltage Positioning,” 2017 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), Boston, Massachusetts, Aug. 2017, pp. 440-443.
41. M. Swilam, A. Naguib, B. Dupaix, W. Khalil, and A. Fayed, “A Calibration-Free Low-Power Supply-Pushing Reduction Circuit (SPRC) for LC VCOs,” 2017 IEEE Int. symposium on circuits and Systems (ISCAS), Baltimore, Maryland, May 2017, pp. 1-4.
40. Ahmed Abdelmoaty, Mohammad Al. Shyoukh, Y.C. Hsu, and Ayman Fayed, “A MPPT Circuit with 25 μW Power Consumption and 98.7% Tracking Efficiency for PV Systems,” IEEE Transactions on Circuits & Systems I, vol. 64, no. 2, pp. 272-282, Feb. 2017.
39. Yongjie Jiang and Ayman Fayed, “A 1A, Dual-Inductor 4-Output Buck Converter with 20-MHz/100-MHz Dual-Frequency Switching and Integrated Output Filters in 65nm CMOS,” IEEE Journal of Solid-State Circuits, vol. 51, no. 10, pp. 2485-2500, Oct. 2016.
38. Mina Nashed and Ayman Fayed, “Spur-Free Current-Mode Hysteretic Boost Converter for Noise-Sensitive Loads,” 2016 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), Abu Dhabi, UAE, Oct. 2016, pp. 93-96.
37. Ahmed Abdelmoaty and Ayman Fayed, “Power Loss Analysis in Single-Step, Single-Inductor Energy-Harvesting-based Power Supplies,” 2016 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), Abu Dhabi, UAE, Oct. 2016, pp. 297-300.
36. Bora Tar and Ayman Fayed, “An Overview of the Fundamentals of Battery Chargers,” 2016 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), Abu Dhabi, UAE, Oct. 2016, pp. 437-440.
35. Ahmed Abdelmoaty, Mohammad Al-Shyoukh, and Ayman Fayed, “A High-Voltage Level Shifter with Sub-Nano-Second Propagation Delay for Switching Power Converters,” 2016 IEEE Applied Power Electronics Conference (APEC), Long Beach, California, Mar. 2016, pp. 2437-2440.
34. Wei Fu, M. Radhakrishnan, S. T. Tan, R. Byrd and Ayman Fayed, “A DCM-only Buck Regulator with Hysteretic-Assisted Adaptive Minimum On-time Control for Low-Power Microcontrollers,” IEEE Transactions on Power Electronics, vol. 31, no. 1, pp. 418-429, Jan. 2016.
33. Chih-Wei Chen and Ayman Fayed, “A Low-Power Dual-Frequency SIMO Buck Converter Topology with Fully-Integrated Outputs and Fast Dynamic Operation in 45-nm CMOS,” IEEE Journal of Solid-State Circuits, vol. 50, no. 9, pp. 2161-2173, Sept. 2015.
32. Yongjie Jiang and Ayman Fayed, “A 1A, 20MHz/100MHz Dual-Inductor 4-Output Buck Converter with Fully-Integrated Bond-Wire-Based Output Filters for Ripple Reduction,” 2015 IEEE Custom Integrated Circuits Conference (CICC), San Jose, California, Sept. 2015, pp. 1-4.
31. Yongjie Jiang and Ayman Fayed, “On-Chip Input and Ground Ringing Suppression in High-Frequency Buck Converters,” 2015 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), Fort Collins, Colorado, Aug. 2015, pp. 1-4.
30. Mina Nashed and Ayman Fayed, “Variable Switching Noise Mitigation in Hysteretic Power Converters using Spur-Free Control,” 2015 IEEE Applied Power Electronics Conference (APEC), Charlotte, North Carolina, Mar. 2015, pp. 410-413.
29. Ahmed Abdelmoaty and Ayman Fayed, “A Single-Step, Single-Inductor Energy-Harvesting-based Power Supply Platform with a Regulated Battery Charger for Mobile Applications,” 2015 IEEE Applied Power Electronics Conference (APEC), Charlotte, North Carolina, Mar. 2015, pp. 666-669.
28. Wei Fu and Ayman Fayed, “A Self-Regulated 588 MHz Buck Regulator with On-chip Passives and Circuit Stuffing in 65nm,” 2014 IEEE Int. Midwest Symposium on Circuits and Systems (MWSCAS), College Station, Texas, Aug. 2014, pp. 338-341. Recipient of best student paper award.
27. Mohamed El Mahalawy, Neven Misljenovic, and Ayman Fayed, “A Load-Pull Approach Using Multi-Frequency Harmonic Tuners for Enhancing PAE and Device Model Accuracy,” 2014 IEEE Int. Midwest symposium on circuits and Systems (MWSCAS), College Station, Texas, Aug. 2014, pp. 603-606.
26. Mohamed El Mahalawy, Scott Patten, Don Landt, Robert Ward, Andy Walker, and Ayman Fayed, “An All-GaN Differential Driver for a 60 V GaN-Based Power Amplifier with 1 GHz Switching Frequency,” 2014 IEEE Wireless and Microwave Technology Conference (WAMICON), Tampa, Florida, Jun. 2014, pp. 1-3.
25. Wei Fu and Ayman Fayed, “Power Conversion Schemes in Mixed-Signal SoCs,” 2014 IEEE Int. symposium on circuits and Systems (ISCAS), Melbourne VIC, Australia, Jun. 2014, pp. 606-609.
24. Chih-Wei Chen, Jeffrey Morroni, David Anderson, and Ayman Fayed, “Dual-Frequency SIMO Power Converters for Low-Power on-Chip Power Grids in SoCs,” 2014 IEEE Applied Power Electronics Conference (APEC), Fort Worth, Texas, Mar. 2014, pp. 1954-1957.
23. Ayman Fayed, “Efficient Powering of RF PAs using DC-DC Power Supplies,” 2013 IEEE Compound Semiconductor IC Symposium (CSICS), Monterey, CA, Oct. 2013, pp. 1-4.
22. Chengwu Tao and Ayman Fayed, “PWM Control Architecture for Spur-Free Operation in Buck Regulators,” IEEE Transactions on VLSI, vol. 21, no. 9, pp. 1596-1607, Sept. 2013.
21. Wei Fu, Siang Tan Tong, and Ayman Fayed, “Switching and Conduction Loss Analysis of Buck Converters Operating in DCM-only Scenarios,” 2013 IEEE Int. symposium on circuits and Systems (ISCAS), Beijing, China, May 2013, pp. 921-924.
20. W. Burkland, C. Tao, and A. Fayed, “Output Switching Noise Spectral Analysis and Modeling in Buck Regulators,” Microelectronics Journal, vol. 44, no. 5, pp. 373-381, Mar. 2013.
19. Chengwu Tao and Ayman Fayed, “A Low-Noise PFM-Controlled Buck Converter for Low-Power applications,” IEEE Transactions on Circuits and Systems I, vol. 59, no. 12, pp. 3071-3080, Dec. 2012. Received the 2015 IEEE CAS Society Darlington Best Paper Award.
18. Chengwu Tao, and Ayman Fayed, “Output Spectrum Analysis of Buck Converters in DCM with PFM Control,” 2012 IEEE Int. symposium on circuits and Systems (ISCAS), Seoul, South Korea, May 2012, pp. 2267-2270.
17. Chengwu Tao and Ayman Fayed, “A GSM Power Amplifier Directly-Powered from a DC-DC Power Converter,” IEEE Microwave and Wireless Components Letters, vol. 22, no. 1, pp. 38-40, Jan. 2012.
16. Chengwu Tao and Ayman Fayed, “A Buck Converter with Reduced Output Spurs using Asynchronous Frequency Hopping,” IEEE Transactions on Circuits and Systems II, vol. 58, no. 11, pp. 709-713, Nov. 2011.
15. Chengwu Tao, and Ayman Fayed, “Analysis and Modeling of Buck Converters Output Spectrum in CCM with PWM Control,” 2011 IEEE Midwest symposium on circuits and Systems (MWSCAS), Seoul, South Korea, Aug. 2011, pp. 1-4.
14. Chengwu Tao, and Ayman Fayed, “Noise Spectrum Manipulation Techniques in Switching Power Converters for Analog and RF Loads,” 2011 Government Microcircuit Applications & Critical Technology Conference (GOMACTech), Orlando, Florida, Mar. 2011.
13. Chengwu Tao, and Ayman Fayed, “Spurious-Noise-Free Buck Regulator for direct-powering of Analog/RF loads using PWM Control with Random Frequency Hopping and Random Phase Chopping,” 2011 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, Feb. 2011, pp. 396-397.
12. Yogesh K. Ramadass, Ayman A. Fayed, and Anantha P. Chandrakasan, “A Fully-Integrated Switched-Capacitor Step-Down DC-DC Converter With Digital Capacitance Modulation in 45 nm CMOS,” IEEE Journal of Solid-State Circuits, vol. 45, no. 12, pp. 2557-2565, Dec. 2010.
11. Oguz Altun, Ayman Fayed, Russell Byrd, Rahmi Hezar, Gaurav Chandra, and Gabriel Gomez, “A 6mW 480MHz Continuous Time SD Modulator with 65dB DR over 5MHz Bandwidth in 65nm CMOS,” 2010 IEEE Int. symposium on circuits and Systems (ISCAS), Paris, France, Jun. 2010, pp. 3989-3992.
10. Ayman Fayed, Russell Byrd, and Baher Haroun, “An adaptive high-voltage protection and common-mode adjustment circuit for passive-active continuous-time sigma-delta ADCs,” Journal of Analog Integrated Circuits and Signal Processing, vol. 62, no. 2, pp. 159-166, Feb. 2010.
9. Yogesh K. Ramadass, Ayman A. Fayed, Baher Haroun, and Anantha P. Chandrakasan, “A 0.16mm2 Completely On-Chip Switched-Capacitor DC-DC Converter using Digital Capacitance Modulation for LDO Replacement in 45nm CMOS,” 2010 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, Feb. 2010, pp. 209-210,209a.
8. Wei Fu, and Ayman Fayed, “A Feasibility Study of High-Frequency Buck Regulators in Nanometer CMOS Technologies,” 2009 IEEE Dallas circuits & Systems Workshop (DCAS), Dallas, Texas, Oct. 2009, pp. 31-34.
7. Ayman Fayed, “Level shifting techniques for Mixed-Signal SoCs in low-voltage nanometer CMOS technologies,” 2009 IEEE Midwest Symposium on Circuits and Systems (MWSCAS), Cancun, Mexico, Aug. 2009, pp. 1102-1105.
6. Ayman Fayed, M. Ismail, “A Low-Voltage, Low-Power CMOS Analog Adaptive Equalizer for UTP-5 Cables,” IEEE Transactions on Circuits and Systems I, vol. 55, no. 2, pp. 480-495, March 2008.
5. Ayman Fayed, M. Ismail, “A 3.7mW, 1.6V CMOS Analog Adaptive Equalizer for a 125Mbps Wire-Line Transceiver,” 2007 IEEE Int. symposium on circuits and Systems (ISCAS), New Orleans, LA, May 2007, pp. 2136-2139.
4. Ayman A. Fayed, and M. Ismail “A Digital Calibration Algorithm for implementing accurate On Chip Resistors,” International Journal of Analog Integrated Circuits and Signal Processing, vol. 47, no. 3, pp. 259-272, June 2006.
3. Ayman Fayed, M. Ismail, “A Low-Voltage, Highly-Linear, Voltage-Controlled Transconductor,” IEEE Transactions on Circuits and Systems II, vol. 52, no. 12, pp. 831-835, Dec. 2005.
2. Ayman A. Fayed, and M. Ismail “A Digital Tuning Algorithm for On-Chip Resistors,” 2004 IEEE Int. symposium on circuits and Systems (ISCAS), Vancouver BC, Canada, May 2004, pp. 936-939.
1. Ayman A. Fayed, and M. Ismail “A High Speed, Low Voltage CMOS Offset Comparator,” International Journal of Analog Integrated Circuits and Signal Processing, vol. 36, no. 3, pp. 267-272, Sept. 2003.
2. Ayman A. Fayed, and M. Ismail "Adaptive Techniques For Analog And Mixed Signal ICs," Springer, Boston. Sept. 06.
1. M. Ismail, Seok-Bae Park, A. A. Fayed, and R.F. Wassenaar, "Operational Transconductance Amplifiers", ch.25, pp. 25-1-19, The VLSI Handbook (Edited by Wai-Kai Chen), 2nd Ed., CRC Press, 2006.
8. Ayman Fayed and Chengwu Tao, “System and Method for Providing Power via a Spurious-Noise-Free Switching Device”, US Patent 8,901,905, granted Dec. 2014.
7. J. Large, H. Edwards, Ayman A. Fayed, P. Cruise, and N. Nayak “Mask Design Elements to Aid Circuit Editing and Mask Redesign,” US Patent 8,330,159, granted December 11, 2012.
6. Ayman A. Fayed, Russell Byrd, and Baher Haroun, “System and method for common mode translation,” US Patent 8,120,425, granted Feb.12, 2012.
5. Yogesh Ramadass, Ayman A. Fayed, and Baher Haroun, “Circuit and Method for a Fully Integrated Switched-Capacitor Step-Down Power Converter,” US Patent 7,907,429, granted March 15, 2011.
4. M. Al-Shyoukh & Ayman A. Fayed, “Level Shifter Circuit,” US Patent 7,994,819, granted August 9, 2011.
3. A. Fayed, “Low-Leakage Level-Shifters with Supply Detection,” US Patent 7,675,345, granted Mar. 9, 2010.
2. Ayman A. Fayed, “Highly-Linear, Wide-Input-Range, Wide-Control-Range, Low-Voltage, Differential Voltage Controlled Transconductor,” US Patent 6724258, granted April 04.
1. Ayman A. Fayed, “High speed offset comparator,” US Patent 6400219, granted June 02.
19. Sita Asar, “Dual-Frequency Dual-Inductor Multiple-Output (DF-DIMO) Buck Converter Topology with Interleaved Output Power Distribution for Dynamic Voltage Scaling Applications,” Ph.D. Thesis, The Ohio State University, 2020.
18. Manmeet Singh, “Switching Power Converter Techniques for Server and Mobile Applications,” Ph.D. Thesis, The Ohio State University, 2020.
17. Manmeet Singh, “High-Frequency, High-Current Switching Power Converters for Mobile and Server Applications,” M.Sc. Report, The Ohio State University, 2019.
16. Muhammad Ahmed, “Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers,” Ph.D. Thesis, The Ohio State University, 2018.
15. Muhammad Ahmed, “Circuit and System Techniques for Low-Noise Buck Regulators for Low-Power Applications,” M.Sc. Report, The Ohio State University, 2017.
14. Ahmed Abdelmoaty, “Circuit and System Techniques for Energy-Harvesting Platforms for Mobile Applications,” Ph.D. Thesis, The Ohio State University, 2016.
13. Mina Nashed, “Variable Spurious Noise Mitigation Techniques in Hysteretic Buck Converters,” Ph.D. Thesis, Iowa State University, 2016.
12. Yongjie Jiang, “Dual-Frequency Dual-Inductor Multiple-Outputs (DF-DIMO) Buck converter topology with Fully-Integrated Output Filters,” Ph.D. Thesis, Iowa State University, 2016.
11. Chih-Wei Chen, “Dual-Frequency Single-Inductor Multiple-Output (DF-SIMO) Power Converter Topology for SoC Applications,” Ph.D. Thesis, Iowa State University, 2015.
10. Wei Fu, “Power Conversion Techniques in Nanometer CMOS Technologies for Low-Power Applications,” Ph.D. Thesis, Iowa State University, 2015.
9. Ahmed Abdelmoaty, “A Sub-Micro Watt Maximum Power Point Tracking Circuit for Photovoltaic Systems,” M.Sc. Report, Iowa State University, 2015.
8. Mina Nashed, “Hysteretic Buck Converters with Spur-Free Control,” M.Sc. Report, Iowa State University, 2015.
7. Yongjie Jiang, “A 1A, 20MHz/100MHz Dual-Inductor 4-Output Buck Converter with Fully-Integrated Bond-Wire-Based Output Filters for Ripple Reduction,” M.Sc. Report, Iowa State University, 2015.
6. Ailing Mei, “Constant-Current Constant-Voltage Switching Battery Charger for Li-Ion Batteries,” M.Sc. Report, Iowa State University, 2015.
5. Yingying Chen, “A Dual-Loop Capacitor-less LDO with Fast Transient Response and High PSR,” M.Sc. Report, Iowa State University, 2014.
4. Mohamed El Mahalawy, “Wide Bandwidth GaN-based Power Modulator for High Efficiency Power Amplifiers,” M.Eng. Report, Iowa State University, 2013.
3. Shibing Zhao, “Capacitor-less high PSR linear regulators,” M.Eng. Report, Iowa State University, 2013.
2. Chengwu Tao, “PWM Control Architecture for Spur-Free Operation in Buck Regulators,” Ph.D. Thesis, Iowa State University, 2011.
1. Wei Fu, “Fully-integrated Buck Regulator with On-chip Passives in 65nm Technology for SoC Applications,” M.Sc. Report, Iowa State University, 2011.