An Investigation on the Performance of Random PWM Controlled Converters

R. Jadeja, A. Ved, S. Chauhan

Abstract


This paper provides an insight on various random pulse width modulation techniques and their effect on spreading the harmonic spectrum for various applications like drives, hybrid electric vehicles and renewable energy sources, for two level as well as three level inverter. Acoustic noise reduction, electromagnetic interference conducted and torque ripple are obvious advantages of random pulse width modulation (PWM). PWM converters with multilevel topology can meet with global quality standards for power supplies. The random PWM technique provides additional advantages. Among others, it may be implemented to achieve switching loss equalization in power switches for cascaded H-Bridge multilevel inverters. This paper provides in depth understanding for different random PWM techniques and their applications.


Keywords


Random PWM; Random SVPWM; Multilevel inverter; drives

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References


M. Sharifzade, H. Vahedi, A. Sheikholeslami, H. Ghoreishy, K. Al-Haddad, "Selective Harmonic Elimination Modulation Technique Applied on Four-Leg NPC," in ISIE 2014-23rd IEEE International Symposium on Industrial Electronics, pp. 2163-2168, Turkey, 2014

M. Sharifzade, H. Vahedi, A. Sheikholeslami, H. Ghoreyshi, K. Al-Haddad, "Modified selective harmonic elimination employed in four-leg NPC inverters," in IECON 2014-40th Annual Conference of the IEEE Industrial Electronics Society, pp. 5196-5201, 2014

M. Sharifzadeh, H. Vahedi, A. Sheikholeslami, P.-A. Labbé, K. Al-Haddad, "Hybrid SHM-SHE Modulation Technique for Four-Leg NPC Inverter with DC Capacitors Self-Voltage-Balancing," IEEE Trans. Ind. Electron., Vol. 62, No. 8, pp. 4890-4899, 2015

H. Vahedi, K. Al-Haddad, P.-A. Labbe, S. Rahmani, "Cascaded Multilevel Inverter with Multicarrier PWM Technique and Voltage Balancing Feature," in ISIE 2014-23rd IEEE International Symposium on Industrial Electronics, pp. 2151-2156, Turkey, 2014

Y. C. Lim. “Shaping the Spectra of the Acoustic Noise Emitted by Three-Phase Inverter Drives based on the New Hybrid Random PWM Technique”, 37th IEEE Power Electronics Specialists Conference, pp. 1-6, 2006

I. A. Bakhovtsevand, A. K. Rakitin. “New PWM methods with deterministic change of carrier frequency”, 2011 International Conference and Seminar on Micro/Nanotechnologies and Electron Devices Proceedings, pp. 406-410, 2011

L. Mathe, Product Sound: Acoustically pleasant motor drives, PhD thesis, Department of Energy Technology, Aalborg University, 2010

L. Solero. “Emission testing for the EMC performance evaluation of an electric wheelchair”, International Symposium on Power Electronics Electrical Drives Automation and Motion 2006, pp. 597-602, 2006

B. Jacob, M. R. Baiju. “Space vector based Dithered Sigma Delta Modulator for two-level inverter to suppress the harmonic spikes”, 38th Annual Conference on IEEE Industrial Electronics Society, pp. 2005-2011, 2012

H. Laaksonen, K. Kauhaniemi, “Voltage and current thd in microgrid with different dg unit and results system ,” CIRED 2008: smart grid for Distribution, ,No. 57, pp. 23–24, 2008

B. Jacob, M. R. Baiju, “Space Vector Quantized Dithered Sigma Delta Modulator for Reducing the Harmonic Noise in Multilevel Converters,” IEEE Trans. Ind. Electron., Vol. 62, No. 4, pp. 2064-2072, 2014

B. Jacob, M. R. Baiju, “Simple multilevel inverter-based induction motor drive scheme using sigma–delta converter with space-vector quantiser”, IET Power Electronics, Vol. 5, No. 8 , pp. 1483-1490, 2012

J. D. Reiss. “Understanding sigma-delta modulation: the solved and unsolved issues,” Journal of Audio Engineering Society,Vol. 56, No.1/2, pp. 49-64, 2008

B. Jacob, M. R. Baiju. “Space Vector based Dithered Sigma Delta Modulator for two-level inverter to suppress the harmonic spikes”, IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), pp. 1-7, 2012

B. Jacob, M. R. Baiju. “Spread spectrum modulation scheme for multilevel inverters using vector quantized sigma delta modulation.” Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 2428-2435, 2012

B. Jacob, M. R. Baiju, “Space vector modulation scheme with direct Vector Quantization for any N-level voltage source inverter”, 2012 IEEE Int. Conf. Power Electron. Drives Energy Syst., pp. 1–6, 2012

B. Jacob, M. R. Baiju, “Vector quantized spread spectrum Pulse Density Modulation for four level inverters,” IEEE Conf. Ind. Electron. Appl., pp. 674–679, 2011

B. Jacob, M. R. Baiju, “Space Vector based Spread Spectrum Modulation scheme for three-level inverters,” 2011 IEEE Appl. Power Electron. Colloq., Vol. 1, pp. 51–56, 2011

B. Jacob, M. R. Baiju, “Spread spectrum modulation scheme for two-level inverter using vector quantised space vector-based pulse density modulation,” IET Electr. Power Appl., Vol. 5, No. 7, pp. 589-596, 2011

B. Jacob, M. R. Baiju. “Vector-Quantized Space-Vector-Based Spread Spectrum Modulation Scheme for Multilevel Inverters Using the Principle of Oversampling ADC”, IEEE transactions on Industrial Electronics, Vol. 60, No. 8, pp. 2969-2977, 2013

B. Jacob, M. R. Baiju. “Space-Vectored–Quantized Sigma-Delta Modulator for reducing the Harmonic Noise in Multilevel Converters.” IEEE Transactions on Industrial Electronics Vol. 62, No. 8, pp. 2064-2072, 2015

M. R. Baiju, B. Jacob, “A new Space Vector Modulation Scheme for any N-level Voltage Source Inverter which directly Quantizes the Reference Space Vector,” 7th IET Int. Conf. Power Electron. Mach. Drives (PEMD 2014), pp. 1-6, 2014

K. Chandra Shekhar, G. Tulasi Ram Das. “Five-level SPWM Inverter for an Induction Motor with Open end Windings”, IEEE International Power and Energy Conference, pp.342-347, 2006

S. –H. Kim, K. –B. Lee, “ Elimination of harmonic spikes using second-order Space Dithered Sigma-Delta Modulation.” 13th European Conference on Power Electronics and Applications, (EPE '09), pp. 1-10, 2009

M. M. Bech. “Random modulation techniques with fixed switching frequency for three phase power converters,” IEEE Transactions on Power Electronics, Vol. 7, pp. 753-761, 2000

A. M. Trzynadlowski, “Power spectra of a PWM inverter with randomized pulse position”, IEEE Power Electronics Specialist Conference, pp. 1041-1047, 1993

M. M. Bech, F. Blabjerg, J. K. Pedersen. “Random modulation techniques with fixed switching frequency for three-phase power converters”, 30th Annual IEEE Power Electronics Specialists Conference Record, pp. 544-551, 1999

S. Oh, Y. Jung, Y. Lim, “ A Two-Phase Dual-Zero Vector RCD-PWM (DZRCD)Technique.” The 30th Annual Conference of the IEEE Industrial Electronics Society, pp. 30–34, 2004

P. F. Leong. “Random Pulse-Width Modulated Neutral-Point-Clamped Inverter With Reduced Common-Mode Switching”, International Conference on Power Electronics and Drives Systems, pp.1435-1440, 2005

J. L. Shyu, T. J. Liang, J. F. Chen, “Digitally-controlled PWM inverter modulated by multi-random technique with fixed switching frequency”, IEE Proceedings Electric Power Applications, pp.62-68, 2001

S. E.Schulz, D. L. Kowalewski, “Implementation of Variable-Delay Random PWM for Automotive Applications”, IEEE Transactions on Vehicular Technology, Vol.56, No. 3, pp. 1427–1433, 2007

L. Mathe, F. Lungeanu, D. Sera, P. O. Rasmussen, J. K. Pedersen. “Spread Spectrum Modulation by Using Asymmetric- Carrier Random PWM”, IEEE Transactions on Industrial Electronics, pp.3710-3718, 2012

L. Mathe, F. Lungeanu, P. O. Rasmussen, J. K. Pedersen. “Asymmetric Carrier Random PWM”, IEEE International Symposium on Industrial Electronics, pp.1218-1223, 2010

Y. –C. Lim. “A new random PWM(SRP-PWM) technique for decreasing acoustic noise radiated from V/F controlled motor drives”, 30th Annual Conference of IEEE Industrial Electronics Society, pp.832-837, 2004

G. Shiny, M. R. Baiju, “A low computation Space Vector PWM scheme for multilevel inverters based on fractal approach,” IEEE Symp. Ind. Electron. Appl., pp. 131–136, 2010

M. R. Baiju. “Space Vector PWM for Multilevel Inverters - A Fractal Approach”, 7th International Conference on Power Electronics and Drive Systems, pp.1230-1237, 2007

G. Shiny, M. R. Baiju, “A Fractal based Space Vector PWM Scheme for General n-Level Inverters”, International Power Electronics Conference, pp. 847–854, 2010

G. Shiny, M. R. Baiju, “A Space Vector Based Pulse Width Modulation Scheme for a 5-Level Induction Motor Drive”, IEEE 9th International Conference on Power Electronics and Drive Systems (PEDS), pp. 292-297, 2011

G. Shiny, M. R. Baiju, “Space Vector based PWM scheme without sector identification for a 4-level dual inverter fed induction motor drive with asymmetrical DC link voltages”, 25th Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2010, pp. 1963–1969.

G. Chen, M. Zhang, and J. Zhao, “Harmonic Distortion Factor of A Hybrid Space Vector PWM Based on Random Zero-vector Distribution and Random Pulse Position,” Int. J. Adv. Inf. Sci. Serv. Sci., Vol. 4, No. 16, pp. 242–250, 2012

K. –S. Kim, Y. –G. Jung, Y. –C. Lim, “A New Hybrid Random PWM Scheme”, IEEE Transactions on Power Electronics, Vol.24, No. 1, pp. 192-200, 2009

K. –S. Kim, Y. –G. Jung, Y. –C. Lim, “Shaping the Spectra of the Acoustic Noise Emitted by Three-Phase Inverter Drives based on the New Hybrid Random PWM Technique.” 37th IEEE Power Electronics Specialists Conference, pp. 1-6, 2006

N. Boudjerda, A. Boudouda, M. Melit, B. Nekhoul, K. El Khamlichi Drissi, K. Kerroum. “Optimized dual randomized PWM technique for reducing conducted EMI in DC-AC converters.” EMC Europe 2011, pp. 701-706, 2011

P. N. Reddy, J. Amarnath, P. L. Reddy. “Hybrid random PWM algorithm for direct torque controlled induction motor drive for reduced harmonic distortion”, 2011 Annual IEEE India Conference (INDICON), pp. 1-5, 2011

C. Hou, C. Shih, P. Cheng,, A. Hava, “Common-Mode Voltage Reduction pulse width Modulation Techniques for ThreePhase Grid Connected Converters”, IEEE Transactions on Power Electronics, pp. 1971-1979, 2012

Y. Shrivastava, C. K. Lee, S. Y. R. Hui, H. S. H. Chung, “Comparison of RPWM and PWM Space Vector Switching Schemes for 3-Level Power Inverters.” IEEE Power Electronic Specialist Conference, Vol. 1, pp. 138–145, 2001

S. Xu, C. Chen. “Random PWM Technique Based Induction Motor Phase Current Reconstruction from DC-link Current of Inverters”, 5th IEEE Conference on Industrial Electronics and Applications, pp. 749–752, 2010

D. S. George, M. R. Baiju, “Random Pulse Width Modulation Technique for a 4-level Inverter,” IEEE 7th International Power Engineering and Optimization Conference, Vol. 64, pp. 369–374, 2013

M. R. Baiju, K. K. Mohapatra, V. T. Somasekhar, K. Gopakumar, L. Umanand, “A Five-Level Inverter Voltage Space Phasor Generation for an Open-end Winding Induction Motor Drive”, IEE Proceedings Electric Power Applications , Vol. 150, No. 5, pp. 531–538, 2003

D. S. George, M. R. Baiju, “Space Vector Based Random Pulse Width Modulation Scheme for a 3-level Inverter in Open-end Winding Induction Motor ConFiguration”, IEEE International Symposium on Industrial Electronics (ISIE), Vol. 64, pp. 742–747, 2012

V. Krishnakumar, V. Kamaraj, S. Jeevananthan, “Random Pulse Width Modulation Technique for Performance Improvement of Multilevel Inverter Brushless DC Motor Drive,” Australian Journal of Basic and Applied Sciences, Vol. 9, No. 16, pp. 162-171, 2015

D. S. George, M. R. Baiju, “Investigations on dependence of duration of active vectors on modulation index for inverters”, IEEE International Symposium on Industrial Electronics, pp. 680–685, 2012

D. S. George, M. R. Baiju. “Decoupled random modulation technique for an open-end winding induction motor based 3-level inverter.” IEEE Symposium on Industrial Electronics & Applications, Vol. 2, pp. 1022-1027, 2009

D. S. George, M. R. Baiju. “Random PWM scheme for 3-level inverter using offset time randomization”, 37th Annual Conference on IEEE Industrial Electronics Society, pp. 1989-1994, 2011

I.A.Bakhovtsev, A. K. Rakitin. “New PWM methods with deterministic change of carrier frequency”, International Conference and Seminar of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM), pp. 406-410, 2011

K. Satyanarayana, J. Amarnath, A. K. Rao, “Two Random PWM Algorithms for Vector Controlled Induction Motor Drives with Low Computational Overhead and Fixed Switching Frequency”, Acta Electrotechnica, Vol. 52, No. 1, pp. 18–24, 2011

J. Chen “Design and Analysis of Low-Acoustic Noise Motor Drivers In Electric Machines and Drives”, IEEE International Conference IEMDC ’09, pp. 1188–1193, 2009

B. M. Begum, T. B. Reddy, “Space Vector Based Random PWM Algorithms Based Direct Torque Controlled Induction Motor Drive.” International Journal of Engineering Research and Applications, Vol.3, No. 5, pp. 754–760, 2013

C. Guoqiang, W. Zhihong, Z. Yuan, Z. Junwei, “Realization of Random Space Vector Pulse Width Modulation Based on Infineon Tricore TC1767/TC1797”, Int. J. Digit. Content Technol. its Appl., Vol. 6, No. 20, pp. 624–632, 2012

Y. Shrivastava, S. Y. R. Hui, “Analysis of random PWM switching methods for 3-level power inverters”, 29th Annual IEEE Power Electronics Specialists Conference, pp. 1381-1387, 1998

Y. Shrivastava, S. Y. R. Hui. “Analysis of Random PWM Switching Methods for Three-Level Power Inverters”, IEEE Transactions on Power Electronics, Vol. 14, No. 6, pp. 1156–1163, 1999

A. Gopinath, A. S. A. Mohammad, M. R. Baiju. “ Fractal Based Space Vector PWM for Multilevel Inverters-A Novel Approach.” IEEE Transactions on Power Electronics, Vol. 56, No. 4, pp. 1230–1237, 2009

S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, J. Rodriguez, M. Pérez, J. Leon. “Recent advances and industrial applications of multilevel converters”, IEEE Transactions on Industrial Electronics, Vol. 57, No. 8, pp. 2553-2580,

H. Vahedi, K. Al-Haddad, Y. Ounejjar, K. Addoweesh “Crossover Switches Cell (CSC): A new multilevel inverter topology with maximum voltage levels and minimum DC sources”, IECON 2013, 39th Annual Conference of the IEEE Industrial Electronics Society, pp.54-59, 2013

H. Vahedi, S.Rahmani, K. Al- Haddad “Pinned mid-points multilevel inverter (PMP): Three-phase topology with high voltage levels and one bidirectionalswitch”. Industrial Electronics Society, IECON 2013, 39th Annual Conference of the IEEE Industrial Electronics Society, pp.102-107, 2013

Y. Shrivastava, S. Y. R. Hui, “Analysis of random PWM switching methods for 3-level power inverters”, 29th Annual IEEE Power Electronics Specialists Conference, pp. 1381-1387, 1998

T. Ramanathan, R. Ramesh, C. K. Subramaniam, K. Ganesan. “Pseudorandom Carrier based Subharmonic PWM for Cascaded Multilevel Inverters”, IEEE International Symposium on Circuits and Systems (ISCAS), pp. 117–120, 2014

B. Jacob, M.R.Baiju. “Harmonic noise reduction in three-level inverter using space vector based Dithered sigma Delta Modulator”, 7th IET international conference on Power Electronics, Machines and Drives (PEMD 2014), pp. 1-6, 2014

B. Jacob, M. R. Baiju, “Space Vector Quantized Dithered Sigma Delta Modulator for Reducing the Harmonic Noise in Multilevel Converters”, IEEE Trans. Ind. Electron., Vol. 62, No. 4, pp. 2064-2072, 2015

S. H. Kim, W. Choi, S, Choi, K. B. Lee, “Combined dithered sigma-delta modulation based random PWM switching scheme”, Journal of Power Electronics, Vol. 9, No. 5, pp. 667–678, 2009

H. Lou, C. Mao, D, Wang, J. Lu, “PWM optimisation for three-level voltage inverter based on clonal selection algorithm”, IET Electric Power Applications, Vol.1, No. 6, pp. 870–878, 2007

R. Adlakha, P. R. Sharma, “Space vector modulation for two level and three level vsi and comparison with wavelet”, 4th International Conference, New Delhi, India , pp. 57–62, 2013 (available at: http://iraj.in/iraj_proc.php?id=31)

H.Khan, E. Miliani, H. Ouzaarou, K. E. K. Drissi. “Random discontinuous space vector modulation for variable speed drives.” IEEE International Conference on Industrial Technology (ICIT), pp. 985-990, 2012

H. Khan, Y. Touzani, K. E. K. Drissi, “Random space vector modulation for electric drives: A digital approach”,. 14th Int. Power Electron. Motion Control Conf. EPE-PEMC 2010, No. 3, pp. 20–24, 2010

H. Khan, E. Miliani, K. E. K. Drissi, “Discontinuous Random Space Vector Modulation for Electric Drives: A Digital Approach,” IEEE Trans. Power Electron., Vol. 27, No. 12, pp. 4944–4951, 2012

M. Lane, D. Ashari, F. Gu, A. Ball, “Investigfation of Motor Current Signature Analysis in Detecting Unbalanced Motor Windings of an Induction Motor with Sensorless Vector Control Drive”, Vibration Engineering and Technology of Machinery, pp. 801- 810, 2015

R. L. Kirlin, S. Kwok, S. Legowski, A. M. Trzynadlowski, “Power spectra of a PWM inverter with randomized pulse position”, IEEE Transactions on Power Electronics, Vol. 6, No. 5, pp. 463-472, 1994

R. Burkart, J. W. Kolar, “Overview and Comparison of Grid Harmonics and Conducted EMI Standards for LV Converters Connected to the MV Distribution,” 1st Power Electronics South America 2012 Conference and Exhibition (PCIM 2012), South America, Saõ Paulo, Brazil, pp. 1-9, September 11-13, 2012

R. Kirlin, S. F. Legowski, A. M. Trzynadlowski. “An optimal approach to random pulse width modulation in power inverters,” 26th Annual IEEE Power Electronics Specialists Conference, pp. 313-318, 1995

R. L. Kirlin, C. Lascu, A. M. Trzynadlowski. “Shaping the Noise Spectrum in Power Electronic Converters.” IEEE Transactions on Industrial Electronics, Vol. 58, No. 7, pp. 2780-2788, 2011

R. L. Kirlin, M. M. Bech, A. M. Trzynadlowski. “Analysis of power and power spectral density in PWM inverters with randomized switching frequency”, IEEE Transactions on Industrial Electronics, Vol.49, No. 2, pp. 486-499, 2002

R. L. Kirlin, M. M. Bech, A. M. Trzynadlowski. “Power spectral density analysis of randomly switched pulse width modulation for DC/AC converters”, 10th IEEE Workshop on Statistical Signal and Array Processing, pp. 373-377, 2000

R. L. Kirlin, M. M. Bech, A. M. Trzynadlowski, B. Huo. “Power and power spectral density in PWM inverters with randomized switching frequency.” 32nd Annual Power Electronics Specialists Conference, pp. 188-192, 2001

R. L. Kirlin, S. Kwok, S. Legowski, A.M. Trzynadlowski. “Power spectra of a PWM inverter with randomized pulse position”, 24th Annual IEEE Power Electronics Specialists Conference, pp. 1041-1047, 1993

A. Napoli, A. D. Lidozzi, L. Solero, “Comparison of Random Modulation Techniques for EMI Reduction in Electric Vehicles”, Proceedings of SPEEDAM , pp. 488–493, 2004

Z. Wang, K. T.. Chau, M. Cheng, “A Chaotic PWM Motor Drive for Electric Propulsion”, IEEE Vehicle Power and Propulsion Conference (VPPC), pp. 3–8, 2008

S. E.Schulz, D. L. Kowalewski, “Implementation of Variable-Delay Random PWM for Automotive Applications”, IEEE Transaction on Vehicular Technology, Vol. 56, No. 3, pp. 1427–1433, 2007

K. Borisov, A. M. Trzynadlowski. “Experimental investigation of a naval propulsion drive model with PWM-based attenuation of the acoustic and electromagnetic noise”, 29th Annual Conference of the IEEE Industrial Electronics Society, Vol. 1, pp. 12-17, 2003

K. Borisov, H. Ginn, A. M. Trzynadlowski, “Mitigation of Electromagnetic Noise in a Shunt Active Power Filter Using Random PWM”, 33rd Annual Conference of the IEEE Industrial Electronics Society, pp. 1886-1891, 2007

K. Borisov, H. L. Ginn, A. M. Trzynadlowski, “Attenuation of Electromagnetic Interference in a Shunt Active Power Filter”, IEEE Transactions on Power Electronics, Vol. 22, No. 5, pp. 1912-1918, 2007

A. Esmaeli, M. Mobini. “Research and Development Random pulse width modulation”, International Research Journal of Applied and Basic Sciences, Vol. 6, No. 9, pp. 1243–1248, 2013

A. Esmaeli, Z. Kohshari, “Application of Random PWM Technique for Reducing EMI”, International Research Journal of Applied and Basic Sciences, Vol.6, No. 9, pp. 1237–1242, 2013

S. Kaboli, J. Mahdavi, A. Agah, “Application of Random PWM Technique for Reducing the Conducted Electromagnetic Emissions in Active Filters”, IEEE Transactions on Industrial Electronics, Vol.54, No. 4, pp. 2333–2343, 2007

D. M. Scholten, N. Ertugru, W. L. Soong, “Micro-Inverters in Small Scale PV Systems: A Review and Future Directions”, Australasian Universities Power Engineering Conference, pp. 1–6, 2013

H. Patel, V. Agarwal. “MPPT Scheme for a PV-Fed Single-Phase Grid-Connected Inverter Operating in CCM With Only One Current Sensor.” IEEE Transaction on Energy Conversion,Vol.24, No. 1, pp. 256–263, 2009

S. Verma, H. K. Verma, M. K. Mohiddin, “Modeling & Analysis Of Standalone Photovoltaic System”, International Journal of Research in Engineering and Technology, Vol.2, No. 11, pp. 259–265, 2013

N. D. Marks, T. J. Summers, R. E. Betz, “Photovoltaic Power Systems: A Review of Topologies, Converters and Controls”, 22nd Australasian Universities Power Engineering Conference (AUPEC), pp. 1–9, 2012

G. Satheesh, T. B. Reddy, C. Saibabu, “A Family of Random PWM Algorithms for Reduction of Torque Ripple and Current Harmonics of Direct Torque Controlled Open End Winding Induction Motor”, Journal of Control, Automation and Electric Ease of Use, pp.349-357, 2014

T. A. Trivedi, R. Jadeja, P. Bhatt. “A Review on Direct Power Control for Applications to Grid Connected PWM Converters”, Engineering, Technology & Applied Science Research, Vol. 5, No. 4, pp. 841–849, 2015

M. K .Sahu, A. K. Panda, B. P. Panigrahi. “Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive.” Engineering, Technology & Applied Science Research, Vol. 2, No. 1, pp. 201–208, 2012




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