Publications
Papers Published In Proceedings of International Conferences
(* No.s in Blue give the No. of Citations as per Scopus)
- Jambukar, S. and Chandramohan, S. 2020, Effects of Kingpin and Caster Offset on Braking Stability of Long Wheelbase Bus. In Advances in Mechanical Engineering (pp. 601-615). Springer, Singapore.
- Jogi, A. and Chandramohan, S. 2020, Zero-Speed Off-tracking Analysis of Tractor-Semitrailer with Split Fifth Wheel Coupling for 90° and 180° Turning Manoeuvres. In Advances in Mechanical Engineering (pp. 1567-1578). Springer, Singapore.
- Manjeet, K. and Sujatha, C. 2020, Comparative Study of Performance of Optimized Valve for Different Flow Indices of Rheological Model. In Advances in Mechanical Engineering (pp. 1191-1202). Springer, Singapore.
- Suresh, K., Shankar, K. and Sujatha, C. 2020, A Novel Passive Mechanism to Improve Induced Strain in Two-DOF Piezoelectric Energy Harvester. In Advances in Mechanical Engineering (pp. 1109-1116). Springer, Singapore.
- Jambukar, S. and Chandramohan, S., Effects of kingpin inclination and caster angle on kinematics and lateral dynamics of long wheelbase school bus, SAE Technical Paper 2019-26-0219, doi: 10.4271/2019-26-0219.
- Mukesh Kumar and Chandra Mohan Sujatha, Study of multi-geometry periodic mounts for reduction of engine vibration, Proc. The 14th International Conference on Motion and Vibration, (MoViC 2018), August 5-8, 2018, Daejeon, Korea.
- Manjeet Keshav and Chandra Mohan Sujatha, Modeling and optimization of non-linear Herschel-Bulkley fluid model based magnetorheological valve geometry, Proc. 2018 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2018), July 9-12, Auckland, New Zealand, DOI: 10.1109/AIM.2018.8452342 2
- S. Rajkumar and C. Sujatha, Vertical road load estimation for a tracked vehicle from measured acceleration data using Kalman filter technique, Proc. The Twentyfifth International Congress on Sound and Vibration (ICSV25), July 8-12, 2018, Hiroshima, Japan.
- R. Pranav and C. Sujatha, Biomechanical modelling of the human hand- arm to study stresses caused by hand-arm vibration, Proc. The Twenty-fifth International Congress on Sound and Vibration (ICSV25), July 8-12, 2018, Hiroshima, Japan.
- Ravikanth GSG and C. Sujatha, Dynamic modeling and simulation of three wheeled hub motor vehicle, Proc. International Transportation Electrification Conference, Pune, India, 13th to 15th Dec 2017.
- Manchi Venkateswararao and C. Sujatha, Design and experimental investigation of centrifugal pendulum vibration absorber for reducing 1st order torsional vibration in an automobile driveline, Proc. 13th International Conference on Vibration Problems (ICOVP), 29th November – 2nd December, 2017, Indian Institute of Technology Guwahati, India.
- Hari M Nair and C. Sujatha, A new rollover detection system for tripped and unstripped rollovers for antiroll safety systems, Proc. 19th International & 14th European-African Regional Conference of the ISTVS, September 25-27, 2017, Budapest, Hungary.
- Sagar Jambukar and C. Sujatha, Study of the effects of caster trail and kingpin offset on kinematics and lateral dynamics of long wheelbase solid axle bus, Proc. 19th International & 14th European-African Regional Conference of the ISTVS, September 25-27, 2017, Budapest, Hungary.
- C. Jahnavi and C. Sujatha, Vibration and stress measurement in different parts of human body when subjected to random excitation, Proc. 6th International Conference on Whole Body Vibration Injuries, June 19th-21st 2017, Gothenburg, Sweden, URI: http://hdl.handle.net/2077/52542, Abstract in Work and Health, 2017; 51 (6), ISSN 978-91-85971-64-0.
- C. Sujatha and Lt. Col. Adheesh Sinha, Analytical and experimental studies on human comfort in a combat vehicle (CV) during steady state runs and firing, Proc. 6th International Conference on Whole Body Vibration Injuries, June 19th-21st 2017, Gothenburg, Sweden, URI: http://hdl.handle.net/2077/52542, Abstract in Work and Health, 2017; 51 (6), ISSN 978-91-85971-64-0.
- P, Sasikumar, C. Sujatha, and K. Chinnaraj, Transient fatigue analysis of exhaust system mounting brackets for commercial vehicle - Correlation, SAE Technical Paper 2017-01-1333, 2017, doi:10.4271/2017-01-1333. (1)
- Kushwaha, B., Chaudhuri, S., and Chandramohan, S., Yaw dynamics of command steered multi axle semitrailer, SAE Technical Paper 2017-26-0345, 2017, doi:10.4271/2017-26-0345.
- Solomon, S., C. Sujatha and S. Sujatha, Design evaluation of a mono-tube magnetorheological (MR) damper valve, Proc. 3rd International Conference on Innovative Design, Analysis & Development Practices in Aerospace and Automotive Engineering (I-DAD), February 22-24, 2018, Chennai, India.
- Solomon, S., C. Sujatha and S. Sujatha (2018) Optimal design of a magnetorheological (MR) damper using finite element method and response surface method, Proc. International Conference on Electrical, Electronics, Computers, Communication, Mechanical and Computing (IEEE-EECCMC), 28-29 January 2018, Vellore, India.
- Solomon, S., C. Sujatha and S. Sujatha, MR damper based prosthetic knee design, Proc. International Conference on Contemporary Design and Analysis of Manufacturing and Industrial Engineering Systems (CDAMIES), February 18 - 20 January, 2018, Tiruchirappallli, India.
- Solomon, S., S. Sujatha and C. Sujatha, Optimal design of a magnetorheological damper using FEM and RSM, Proc. NCETCPDIC-2017, July 20-21, Bishoftu, Ethiopia.
- S.G.S. Ravikanth and C. Sujatha, Ride assessment of three wheeler with hub motor, Proc. International Conference on Automobile Engineering, ICAE, 2017, Jan. 6-7, Coimbatore.
- Bhagat Alok and C. Sujatha, Determination of Young's modulii and damping ratios of flexible hoses from experimental modal analysis, Proc. 23rd International Congress on Sound and Vibration (ICSV 23), Athens, Greece, 10-14 July 2016.
- C. P. Sudheesh Kumar, C. Sujatha, K. Shankar, Effect of geometry on the vibro-acoustic response of beams under moving point loads. Proc. 23rd International Congress on Sound and Vibration (ICSV 23), Athens, Greece, 10-14 July 2016.
- C. P. Sudheesh Kumar, C. Sujatha, K. Shankar, An investigation of the influence of beam geometry on the acoustic response due to a moving oscillator, Noise Control 2016, May 22 - May 25, 2016, Gniew, Poland.
- Sujatha Chandramohan and Ajay Varma, Theoretical and experimental modal analysis of an acoustic guitar, Proc. Noise Control 2016, May 22 - May 25, 2016, Gniew, Poland.
- Solomon, S., S. Sujatha and C. Sujatha (2015). Design of controller for single-axis knee using MR damper, Proc. ECCOMAS Thematic Conference on Multibody Dynamics, June 29-July 2, Barcelona, Catalonia, Spain, 989-998.
- Solomon Seid, S.Sujatha and Sujatha Chandramohan, Design of controller for single axis knee using hydraulic damper, IEEE Conference Publications, AFRICON 2015, September 14-17, Addis Ababa, Ethyopia, DOI: 10.1109/AFRCON.2015.7331868, 467-471. (2).
- S. Kore and C. Sujatha, Effects of macroporosity in poroelastic materials on noise control of acoustic cavity, Proc. Noise and Vibration- Emerging Technologies (NOVEM 2015), Dubrovnik, Croatia, April 13-15, 2015.
- Chandramohan Sujatha, S Rajkumar, Bhagat Alok Dewanand and S Narayanan, Comparison of various techniques used for estimation of input force and computation of frequency response function (FRF) from measured response data, Proc. 22nd International Congress on Sound and Vibration (ICSV22), July 12 -16, 2015, Florence, Italy.
- Sajeev. R. K and Sujatha Chandramohan, Analysis of critical hunting speed and running safety of conventional railway vehicle truck on curved track, Proc. ECCOMAS Thematic Conference on Multibody Dynamics, 2015, June 29 - July 2, 2015, Barcelona, Spain.
- Shreya R. Kamath, Sudheesh Kumar C. P. and C. Sujatha, Effect of geometry modification on the natural frequencies of simply supported beams, Paper 0419, Proc. Sixth International Conference on Theoretical, Applied, Computational and Experimental Mechanics (ICTACEM), December 29-31, 2014, IIT Kharagpur, IndiaBottom of Form.
- Sudheesh Kumar C. P., C. Sujatha and Shankar K., A comparative study of the dynamic behaviour of uniform and sinusoidal beams under high speed moving loads, Paper 266, Proc. Sixth International Conference on Theoretical, Applied, Computational and Experimental Mechanics (ICTACEM), December 29-31, 2014, IIT Kharagpur, India.
- Sudheesh Kumar C. P., C. Sujatha and Shankar K., Vibro-acoustic behaviour of a non-uniform beam traversed by a moving point load” , Proc. The Twelfth International Conference on Motion and Vibration Control (MOVIC), Aug. 4-6, 2014, Sapporo Japan.
- Sudheesh Kumar C.P., C. Sujatha and Shankar Krishnapillai, Vibrations of non-prismatic simply-supported beams under moving loads: Resonances and anti-resonances, Proc. 11th International Conference on Vibration Problems (ICOVP-2013), 9-12 September 2013, Lisbon, Portugal.
- Geethanjali, G. and C. Sujatha, Study of biomechanical response of human hand-arm to random vibrations of steering wheel of tractor, Proc. 13th International Conference on Computational & Experimental Engineering and Sciences, Seattle, USA, May 24 - 28, 2013.
- Itankar Jitendra and C. Sujatha, Experimental studies on particle damping in cantilever beams, Proc. 20th International Congress on Sound and Vibration (ICSV20), 7-11 July, 2013, Bangkok, Thailand. (1)
- Geethanjali, G. and C. Sujatha, Study of Biomechanical response of human hand-arm to steering wheel vibrations, Proc. 20th International Congress on Sound and Vibration (ICSV20), 7-11 July, 2013, Bangkok, Thailand.
- S. Madhavan, Rajeev Jain, C. Sujatha and A. S. Sekhar, (2013), Vibration behaviour of turbine rotor with directionally solidified and equi-axed blades, Proc. International Conference on Computer Aided Engineering, IIT Madras, Chennai, Dec. 19 to 21.
- Madhavan S, Sankar Kumar J, Rajeev Jain, C. Sujatha and Sekhar A S, Flutter and forced response vibration characteristics of a turbo fan bladed disk, Proc. ASME 2013 Gas Turbine India Conference, Bengaluru, Dec. 5 to 6, 2013.
- S. Madhavan, C. Sujatha, Madhavan, S, Rajeev Jain and A. S. Sekhar, Condition monitoring of turbine rotor blade on a gas turbine engine, Proc. 20th International Congress on Sound and Vibration (ICSV20), 7-11 July, 2013, Bangkok, Thailand.
- Sajeev, R. K. and C. Sujatha, Influence of primary suspensions on dynamics of single wheelset moving on curved tracks with single-point and two-point wheel-rail contact, Proc. 20th International Congress on Sound and Vibration (ICSV20), 7-11 July, 2013, Bangkok, Thailand.
- B.M.M.A. Sanjith, C. Sujatha, T. Jayakumar Symbolic dynamics based bearing fault detection, IEEE 5th India International Conference on Power Electronics (IICPE), 01/2012. (1)
- S. Narayanan, C. Sujatha and R.S. Prabakar, Semi-active control of half car vehicle model traversing rough road with magneto rheological suspension, Proc. 23rd International Congress of Theoretical and Applied Mechanics (ICTAM2012), August 19-24, 2012, Beijing, China.
- Hemantha kumar and C. Sujatha, Analytical and experimental studies on dynamic behaviour of a rail vehicle moving on straight track, Proc. 7th International Conference on Vibration Engineering and Technology of Machinery (VETOMAC VII), 21-24, November, 2011, Shanghai, China.
- Sharad Kumar Agarwal, G. Narayanan, A. Meher Prasad and C. Sujatha, Effect of track on the dynamics of railway steel plate girder bridges, Proc. 18th International Congress on Sound and Vibration (ICSV18), Rio De Janeiro, Brazil, July 10-14, 2011.
- C. Sujatha, M. Nouby and K. Srinivasan, Reduction of automotive brake squeal through pad geometrical nodifications: A numerical study, Proc. International Conference on Frontiers in Automobile and Mechanical Engineering (FAME–2010), Chennai, 25th-27th November 2010, Paper AU-13. (1)
- Hemantha kumar and C. Sujatha, Vertical dynamics of an Indian Railway vehicle moving on straight track, Paper 10, Proc. of The Tenth International Conference on Computational Structures Technology, September 14-17, 2010, Valencia, Spain.
- Hemantha kumar and C. Sujatha., Analytical and experimental studies on lateral dynamics of a railway vehicle moving on straight track, Paper 294, Proc. International Congress on Sound and Vibration (ICSV17), July 18-22, 2010, Cairo, Egypt,.
- B. Janarthanan, Chandramouli Padmanabhan and C. Sujatha, Modeling of diesel engine and automatic transmission of a tracked vehicle, Proc. of SAE 2009 International Powertrains, Fuels & Lubricants Meeting, Florence, Italy, June 15-17, 2009, SAE paper no. 2009-01-1860. (1)
- B.Janarthanan, C. Sujatha and Chandramouli Padmanabhan, Skid steering analysis of tracked vehicles, Proc. International Mobility Engineering Congress and Exposition 2009, Chennai, Dec. 13-15, SAE paper No. 2009-28-0063.
- S. Ramesh and C. Sujatha, Studies on vehicle with hydro-pneumatic strut, Proc. Ninth International Conference on Vibration Problems (ICOVP2009), IIT, Kharagpur, India, 19-22, January, 2009, pp.
- K. Ganesh Babu and C. SuC. Sujathajatha, Dynamic effect of the rail/wheel irregularities on typical Indian Railway track system’, Proc. Ninth International Conference on Vibration Problems (ICOVP2009), IIT, Kharagpur, India, 19-22, January, 2009.
- K. Ganesh Babu , and C. Sujatha, “A study of the dynamic Behaviour of a typical Indian Railway track system’, Proc. Ninth International Conference on Computational Structures Technology (CST2008), Athens, Greece, 2-5 September, 2008.
- R.S Prabakar, C. Sujatha and S. Narayanan, Optimization of H∞ controller with preview for semi-active magnetorheological suspension system, Paper 78, Proc. Ninth International Conference on Computational Structures Technology (CST2008), Athens, Greece, 2-5 September 2008.
- Prabakar R. S., C. Sujatha. and Narayanan S., Magnetorheological damper for vehicular applications” , Proc. International Conference on Smart Devices Modelling of Materials and Systems, January 10-12, 2008, IIT Madras, India.
- Lt. Cdr.R.K.Sharma, C. Sujatha and A.S. Sekhar, Gear fault diagnosis by wavelet packet decomposition of motor current signature, Proc. Fourth ICTACEM, 27-29,2007,IIT Kharagpur, India.
- M.K.Ravishankar and C. Sujatha, Stationary response of a military tracked vehicle, , Proc. Fourteenth International Congress on Sound and Vibration (ICSV14), 9-12 July, 2007, Cairns, Australia, p777.
- Prabakar R. S., C. Sujatha. and Narayanan S. Design, fabrication, experimental and mathematical characterization of magnetorheological (MR) Damper for Vehicular Applications, Proc. International Conference on Theoretical, Applied, Computational and Experimental Mechanics (ICTACEM 07), December 27-29, 2007, IIT Kharagpur, India.
- Gireesh Kumar V. R., C. Sujatha and M.P. Ramesh, Structural dynamic analysis of wind turbine rotor blade, Proc. International Conference on Computer Aided Engineering (CAE 2007), Dec. 13-15, 2007, Chennai
- Sudeep, U., A.S.N. Prasad, C. Sujatha, Experimental evaluation of different active vibration control algorithms for a smart structure” , Proc. 2nd International Congress on Computational Mechanics and Simulation, Guwahati, December 8-10, 2006, pp.
- R. S. Prabakar, S. Narayanan, C. Sujatha, Optimal control of semi-active vehicle suspension with sky-hook control, Proc. 2nd International Congress on Computational Mechanics and Simulation, Guwahati, December 8-10, 2006.
- M.K.Ravishankar and C. Sujatha, Dynamic analysis of a tracked vehicle fitted with hydrogas suspension, Proc. Thirteenth International Congress on Sound and Vibration (ICSV13), July 2-6, 2006, Vienna, Austria. (2) .
- A.S.S. Sivaram and C. Sujatha, Multi-objective optimization of vehicle suspension parameters, Proc. Thirteenth International Congress on Sound and Vibration (ICSV13), July 2-6, 2006, Vienna, Austria. (1) .
- Hemantha kumar and C. Sujatha, Vertical dynamic analysis of a typical Indian railway vehicle, Proceedings of 2nd International Congress on Computational Mechanics and Simulation, 467- 475, Guwahati, December 8-10, 2006, India. .
- Hemantha Kumar and C. Sujatha, Lateral dynamic analysis of a railway vehicle wheelset, Paper No. 221, Proc. 14th International ISME conference on Mechanical Engineering in Knowledge Age, Dec. 12-14, 2005, Delhi College of Engineering, Delhi. .
- G. Jayaprasad and C. Sujatha, Two approaches to optimal location of sensors/actuators for active vibration control of square plate, Proc. International Conference on Computational and Experimental Engineering and Sciences (ICCES05), Dec. 1-6, 2005, IIT Madras, Chennai, pp. 3173-78. .
- G. Jayaprasad and C. Sujatha, Model reduction studies on a smart plate’, Proc. International Conference on Advances in Materials, Product Design and Manufacturing Systems (ICMPM 2005), 12-14 Dec., 2005, Sathyamangalam, India, pp. 157-163. .
- G. Jayaprasad and C. Sujatha, Location of sensors/actuators for active vibration control, based on modal controllability, Proc. International conference on Advances in Materials, Product Design and Manufacturing Systems (ICMPM 2005), 12-14 Dec., 2005, Sathyamangalam, India, pp.383-389. .
- M.Amarnath, C. Sujatha and S.Swarnamani, Classification of gear wear using artificial neural networks, Proc. Twelfth International Congress on Sound and Vibration (ICSV12), 11-14 July 2005, Lisbon, Portugal. paper no. 477. (1)
- J. Manjusha, C. Sujatha and Venkatesh Balasubramanian, Response of spine to vehicular vibration, Proc. Twelfth International Congress on Sound and Vibration (ICSV12), 11-14 July 2005, Lisbon, Portugal. .
- M. Amarnath, C. Sujatha and S. Swarnamani, Gear fault detection using oil film thickness and vibration analysis, Paper No. 232, Proc. of The International Conference on Recent Advances in Mechanical and Materials Engineering (ICRAMME-2005), 30 - 31 30-31 May 2005, Kuala Lumpur, Malaysia, pp. 788-792. .
- K. V. Gangadharan, C. Sujatha, V. Ramamurti, (2004) Experimental and analytical Ride comfort evaluation of a railway coach, Paper # 249, Proc. IMAC-XXII A Conference & Exposition on Structural Dynamics, Dearborn, Michigan, January 26-29, 2004. .
- Suryanarayana A.N. Prasad, M.L. Ratnaji Rao, S. Swarnamani and C. Sujatha, Automatic vibration control of an isotropic plate using piezoelectric actuators, Proc. Third Conference on Vibration Engineering and Technology of Machinery (VETOMAC) & Fourth Asia-Pacific Conference on Systems Integrity and Maintenance (ACSIM), 6-9 Dec 2004, IIT New Delhi. .
- V.R. Pramod, Vivek Jaiswal, C. Sujatha and S.Ramesh, Characterization of the dynamic behaviour of hydro pneumatic suspension, Proc. Second International Conference on Vibration Engineering and Technology of Machinery, 16-18 Dec., 2002, Mumbai, India. .
- C.D.Parmar, Manoj Gupta and C. Sujatha, Dynamic analysis of off-road vehicles, Proc. Second International Conference on Vibration Engineering and Technology of Machinery, 16-18 Dec., 2002, Mumbai, India. .
- C. Sujatha and C.Chandran, On various specialized vibration techniques for detection of bearing faults, Proc. IMAC-XX: A Conference on Structural Dynamics, Los Angeles, California, Feb. 4-7, 2002, pp.1306-1312. .
- C. Sujatha and P.Tejesu, Heavy vehicle dynamics-comparison between leaf spring and hydro pneumatic suspensions, Proc. IMAC-XX: A Conference on Structural Dynamics, Los Angeles, California, 2002, pp.311-317. (1)
- N.Karuppaiah, C. Sujatha and V.Ramamurti, Numerical analysis of vibration response in a light passenger vehicle, Proc. IMAC-XX: A Conference on Structural Dynamics, Los Angeles, California, Feb. 4-7, 2002, pp.295-304. .
- N.Karuppaiah, C. Sujatha and V.Ramamurti, Computer simulation of vehicle handling behaviour by rigid body/finite element modelling, Proc. SIAT 2001-SAE Conference, Pune, Jan.10-13, SAE Paper No. 2001–01-0031, pp.355-366, 2001. .
- K.Rameshwar Reddy and C. Sujatha, Frequency domain sensitivity analysis of yaw rate and lateral acceleration response of front wheel steering vehicles, Proc. SIAT 2001-SAE Conference, Pune, Jan.10-13, SAE Paper No.2001-01-0035, pp.385-395, 2001. .
- K.Rameshwar Reddy and C. Sujatha, Lateral dynamic studies of a heavy vehicle, Proc. International Conference on Vibration Engg. and Technology of Machinery, VETOMAC-I, I.I.Sc. Bangalore, 25-27 Oct. 2000. .
- N.Karuppaiah, C. Sujatha, V.Ramamurti and P.S.Deshpande, Vibration analysis in a light passenger vehicle by rigid body/finite element modeling, Proc. International Conference on Vibration Engg. and Technology of Machinery 'VETOMAC-I, I.I.Sc., Bangalore, 25-27 Oct.2000. .
- K.V.Gangadharan, C. Sujatha and V.Ramamurti, Railroad vehicle dynamics', Proc. of the Asia Pacific Vibration Conference '99 (A-PVC '99), Dec.13-15, 1999, Singapore, pp.939-944. .
- N.Karuppaiah, C. Sujatha and V.Ramamurti, Modal and vibration /stress analysis of a passenger vehicle by FEM', Proc. Symposium on International Automotive Technology (SIAT '99), Pune, India, 13-16 Jan.1999, SAE Tech. Paper Services 990003. (4)
- P.Geena George, V.Ramamurti and C. Sujatha, Dynamic analysis of railroad vehicles, Proc. IUTAM-IITD International Winter School on Optimum Dynamic Design using Modal Testing and Structural Dynamic Modification (15-19 Dec. 1997), pp.355-364. .
- C. Sujatha, S.Thanooja, M.Hanumantha Rao and S.Swarnamani, A study on change in modal parameters with damage in composite specimens, Proc. International Modal Analysis Conference XV, Orlando, U.S.A., Feb.3-6, 1997, pp. 1607-1613. (2)
- C. Sujatha and S.Thanooja, The use of modal parameters in non-destructive evaluation of damage in composite structures, Proc. of 14th World Conference on NDT, New Delhi, India, Dec.8-13, 1996, pp.1141-1146. .
- V.Ramamurti, H.V.Nayak and C. Sujatha, Static and dynamic analysis of spur and bevel gears using FEM, Proc. International Conference on Advances in Mechanical Engineering, Dec.20-22, 1995, Bangalore, India, pp.1291-1313. .
- M.Subrahmanyam and C. Sujatha, Tool wear recognition in drilling through neural networks, Proc. International Conference on Advances in Mechanical Engineering, Dec.20-22, 1995, Bangalore, India, pp.603-623. .
- V.Ramamurti and C. Sujatha, Analytical determination of dynamic stress on practical cement mills using random vibration concept, Proc. of Second International Congress on Recent Developments in Air-and Structure-Borne Sound and Vibration, March 4-6, 1992, Auburn University, USA, pp.889-896. .
- Sujatha Chandramohan and V.Ramamurti, Vibration response of buses, Proceedings of the Fourth International Conference on CAD, CAM, Robotics and Factories of the Future, December 19-22, New Delhi, 1989, pp.334-346. .
- C. Sujatha and J.P.Raina, Performance of BJT and FET front-ends in optical transimpedance pre-amplifiers, Proc. International Symposium on Opto-Electronic Imaging, December 2nd-5th, 1985, New Delhi, pp.518-523.