Department DIIEM

RESEARCH ACTIVITY

Development of new analytical-numerical techniques, and implementation of computing codes, for the solution of diffraction problems from periodic structures. Study of natural and artificial materials, in particular nanostructured ones and their use in electronic systems for applications in various sectors such as biomedicine, chemistry, energy, physics, telecommunications. Design of innovative diffractive optical components, selective frequency surfaces, photon crystals and electromagnetic band gap metamaterials. Development of new analytical-numerical techniques, and implementation of computing codes, for the solution of direct and inverse problems of electromagnetic scattering from dielectric and conductor objects immersed in multilayer structures. Synthesis, implementation and experimental characterization of antennas and passive components in waveguides and innovative planar and integrated structures for microwave applications, millimeter and sub-millimeter waves and optical frequencies. Research activities about the calculation and measurement of exposure levels to electrical, magnetic and electromagnetic fields, for the protection and safety of human health. Testing and monitoring activities on environmental electromagnetic pollution, assessment of the risk of exposure to electromagnetic fields at workplaces. Study of reclamation techniques and design of innovative shielding materials. Study of sensors and devices for medical and biological application. Georadar research: design of innovative multi-antenna and multi-polarization sensors; Improvement of data-processing techniques for the estimation of geometrical and physical parameters of interest; Development of protocols and guidelines for the effective use of georadar in civil engineering and detection of antipersonnel mines; Interaction of georadar with other non-invasive investigation techniques. Development of electromagnetic techniques for the heating of hydrogen plasmas to be used in nuclear fusion energy research: study of the interaction between electromagnetic waves and plasma, design of waveguide components and radio frequency and microwave launchers capable of operate with high powers and "complex" electromagnetic environment characterized by low dielectric rigidity (board plasma) and presence of structures of various nature such as other launchers, probes, plasma confinement elements etc. The Laboratory also carries out teaching activities at S.S.D. Electromagnetic fields (09 / F1 ex-ING-INF / 02).

PUBLICATIONS

International Journals

1. S. Ceccuzzi, C. Ponti, G. Ravera, and G. Schettini, “Physical Mechanisms and Design Principles in Mode Filters for Oversized Rectangular Waveguides,” IEEE Transactions on Microwave Theory and Technique, Volume 65, Issue 8, August 2017, Article number 7891599, Pages 2726-2733.
2. C. Ponti, M. Santarsiero, G. Schettini “Electromagnetic scattering of a pulsed signal by conducting cylindrical targets embedded in a half-space medium," IEEE Transactions on Antennas and Propagation, Volume 65, Issue 6, 2017, Article number 7906535, Pages 3073-3083.
3. S. Ceccuzzi, C. Ponti, and G. Schettini “Directive EBG Antennas Based on Lattice Modes," IEEE Transactions on Antennas and Propagation, vol. 65, no 4, pp. 1691 – 1699, April 2017
4. S. Ceccuzzi, V. Jandieri, P. Baccarelli, C. Ponti, and G. Schettini, “On Beam Shaping of the Field Radiated by a Line Source Coupled to Finite or Infinite Photonic Crystals,” J. Opt. Soc. Am. A, vol. 33, no. 4, pp. 764-770, April 2016. doi: 10.1364/JOSAA.33.000764
5. S. Ceccuzzi, C. Ponti, G. Ravera, and G. Schettini, “Mode filters for oversized rectangular waveguides: a modal approach,” IEEE Transactions on Microwave Theory and Technique, vol. 63, no.8, pp. 2468-2481, August 2015. ISSN: 0018-9480, doi: 10.1109/TMTT.2015.2447537
6. M. A. Fiaz, F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Spectral domain solution to the electromagnetic scattering of a two-dimensional beam by cylinders buried below a flat interface,” Near Surface Geophysics, vol. 13, no. 3, pp. 219-225, April 2015. ISSN: 1569-4445
7. C. Ponti, and S. Vellucci, “Scattering by conducting cylinders below a dielectric layer with a fast noniterative approach,” IEEE Transactions on Microwave Theory and Technique, vol. 63, no.1, pp. 30-39, January 2015. ISSN: 0018-9480, doi: 10.1109/TMTT.2014.2376553
8. S. Ceccuzzi, L. Pajewski, C. Ponti, and G. Schettini, "Directive EBG antennas: a comparison between two different radiating mechanisms," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 10, pp. 5420 - 5424, Oct. 2014. doi: 10.1109/TAP.2014.2346174
9.  F. Frezza, E. Piuzzi, C. Ponti, L. Pajewski, and G. Schettini, “Radiation-enhancement properties of an X-band woodpile EBG and its application to a planar antenna” International Journal of Antennas and Propagation, vol. 2014, 15 pp, 2014. doi:10.1155/2014/729187
10. M. A. Fiaz, F. Frezza, C. Ponti, and G. Schettini, “Electromagnetic scattering by a circular cylinder buried below a slightly rough Gaussian surface,” J. Opt. Soc. Am. A, Vol. 31, pp. 26-34, January 2014. ISSN: 1084-7529, doi: 10.1364/JOSAA.31.000026
11. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Through-wall electromagnetic scattering by N conducting cylinders,” J. Opt. Soc. Am. A, Vol. 30, pp. 1632-1639, August 2013. ISSN: 1084-7529, doi: 10.1364/JOSAA.30.001632
12. F. Frezza, L. Pajewski, C. Ponti, G. Schettini, and N. Tedeschi “Cylindrical-Wave Approach for electromagnetic scattering by subsurface metallic targets in a lossy medium,” Journal of Applied Geophysics, Vol. 97, pp. 55-59, April 2013. ISSN: 0926-985,1doi: 10.1016/j.jappgeo.2013.01.004
13.  F. Frezza, L. Pajewski, C. Ponti, G. Schettini e N. Tedeschi, “On some numerical aspects of the scattering problem by buried cylinders”, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, Vol. 32, pp. 1809-1820, 2013. ISSN: 0332-1649, doi: 10.1108/COMPEL-10-2012-0275
14. M. A. Fiaz, F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Asymptotic solution for the scattered field by cylindrical objects buried beneath a slightly rough surface,” Near Surface Geophysics, vol. 11, no. 6, pp. 177-183. , January 2013 ISSN: 1569-4445, doi: 10.3997/1873-0604.2012021
15.  F. Frezza, L. Pajewski, C. Ponti, G. Schettini, and N. Tedeschi, “Electromagnetic scattering by a metallic cylinder buried in a lossy medium with the Cylindrical Wave Approach,” IEEE Geoscience and Remote Sensing Letters, vol. 10, no. 1, pp.179-183, January 2013.ISSN: 1545-598X, doi: 10.1109/LGRS.2012.2197172
16. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Line-source scattering by buried perfectly-conducting circular cylinders,” International Journal of Antennas and Propagation, vol. 2012, 7 pp. , 2012. ISSN: 1687-5877, doi: 10.1155/2012/261818
17.  F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Accurate wire-grid modeling of buried conducting cylindrical scatterers,” Nondestructive Testing and Evaluation, vol. 27, no. 3, pp. 199-207, 2012.ISSN: 1058-9759, doi: 10.1080/10589759.2012.665921
18. M. A. Fiaz, F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Scattering by a circular cylinder buried under a rough surface: the Cylindrical Wave Approach,” IEEE Transactions on Antennas and Propagation, vol. 60, no. 6, pp. 2834-2842, June 2012. ISSN: 0018-926X, doi: 10.1109/TAP.2012.2194641
19. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Application of the Cylindrical Wave Approach to the simulation of buried utilities,” International Journal of Geophysics, vol. 2011, 8 pp., 2011. ISSN: 1687-885X, doi: 10.1155/2011/974518
20. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Scattering by dielectric circular cylinders in a dielectric slab,” Journal of Optical Society of America A, vol. 27, no. 4, pp. 687-695, April 2010. ISSN: 1084-7529, doi: 10.1364/JOSAA.27.000687
21. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Directivity-enhancement of double-slot antennas by a woodpile EBG,” Electromagnetics, vol. 30, no. 1-2, pp. 69-81, January 2010. ISSN: 0272-6343 0272-6343, doi: 10.1080/02726340903485323
22. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Investigations on the effects of EBG superstrates on antenna performance,” Microwave and Optical Technology Letters, vol. 51, no. 11, pp. 2769-2774, November 2009. ISSN: 0895-2477 0895-2477, doi: 10.1002/mop.24737
23. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Scattering by perfectly-conducting circular cylinders buried in a dielectric slab through the Cylindrical Wave Approach,” IEEE IEEE Transactions on Antennas and Propagation, vol. 57, n. 4, pp. 1208-1217, April 2009. ISSN: 0018-926X, doi: 10.1109/TAP.2009.2015811 
24. F. Frezza, L. Pajewski, S. Paulotto, C. Ponti, and G. Schettini, “Application of a woodpile superstrate for directivity enhancement of antennas,” Compel: The International Journal for Computation and Mathematics in Electric and Electronic Engineering, vol. 27, no. 6, pp. 1219-1226, 2008. ISSN: 0332-1649, doi: 10.1108/03321640810905701

Book chapters

1. F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “EBG superstrates for directivity enhancement of antennas,” in Selected topics in photonic crystals and metamaterials, A. Andreone, A. Cusano, A. Cutolo, V. Galdi, Editors, chapter 6, pp. 215-238, World Scientific Publishing Co., Singapore, 2011. ISBN: 978-981-4355-18-6
2. C. Ponti, “Development of new methods for the forward solution of the forward scattering by buried objects.” State of the art and open issues, chapter in Cost action Tu1208 "Civil Engineering Applications of Ground Penetrating Radar" Proceedings of First Action General Meeting, pp.109-115, Aracne, Rome, 2013. ISBN: 978-88-548-6190-9
3. C. Ponti, “Methods for the electromagnetic forward scattering by buried objects”, chapter in Civil Engineering Applications of Ground Penetrating Radar, editors L. Pajewski and G. Schettini, pp. 197-217, Springer, 2015.  ISBN: 978-3-319-04812-3

Conference Proceedings

• Ponti, C., Santarsiero, M., & Schettini, G. “Modelling of through-the-wall scenarios with the CWA”. Paper presented at the Proceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017, 1832-1835. Verona; Italy; 11-15 September 2017.

 

• Ceccuzzi, S., Ponti, C., & Schettini, G. “Lattice modes paving the way to printable efficient antennas.” Paper presented at the Proceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017, 1089-1092. ; Verona; Italy; 11-15 September 2017.

 

• Jandieri, V., Baccarelli, P., Valerio, G., Ceccuzzi, S., Ponti, C., & Schettini, G. “Efficient and rigorous analysis of leaky modes in 2-D EBG guiding structures.” Paper presented at the Proceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017, 444-445. Verona; Italy; 11-15 September 2017.

• Baccarelli, P., Jandieri, V., Valerio, G., Schettini, G. “Efficient computation of the lattice sums for leaky waves using the Ewald method”, 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, 15 May 2017, Article number 7928642, Pages 3222-3223, 11th European Conference on Antennas and Propagation, EUCAP 2017; Paris; France; 19-24 March 2017.

 

• Ponti, C., Schettini, G. “Direct scattering methods in presence of interfaces with different media”, 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, 15 May 2017, Article number 7928469, Pages 1707-1710, 11th European Conference on Antennas and Propagation, EUCAP 2017; Paris; France; 19-24 March 2017.

 

•  Jandieri, V., Baccarelli, P., Ponti, C., Schettini, G. “Full-wave analysis of leaky modes in 2-D EBG waveguides” 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, 15 May 2017, Article number 7928613, Pages 3224-3225, 11th European Conference on Antennas and Propagation, EUCAP 2017; Paris; France; 19-24 March 2017.

 

• Ponti, C., Schettini, G. “On time-domain use of the cylindrical wave approach”, 2017 International Applied Computational Electromagnetics Society Symposium - Italy, ACES 2017, 1May 2017, Article number 7916392, 2017 International Applied Computational Electromagnetics Society Symposium - Italy, ACES 2017; Firenze; Italy; 26-30 March 2017.

 

• Ponti, C., Ceccuzzi, S., Schettini, G., Baccarelli, P., “Tapered EBG superstrates for low-permittivity resonator antennas”, 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 – Proceedings, 25 October 2016, Article number 7695881, Pages 345-346, 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016; El Conquistador ResortFajardo; Puerto Rico; 26 June-1 July 2016.

 

• Ponti, C., Santarsiero, M., Schettini, G. ,“Recent advancements in the forward scattering with the Cylindrical Wave Approach”, 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016, 19 September 2016, Article number 7571464, Pages 598-599, 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016; Espoo; Finland; 14-18 August 2016.

 

• Ceccuzzi, S., Jandieri, V., Baccarelli, P., Ponti, C., Schettini, G. , “Directive scattering by a line source coupled to infinite or finite Electromagnetic Band-Gap media”, 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016, 19 September 2016, Article number 7571411, Pages 407-408, 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016; Espoo; Finland; 14-18 August 2016.

 

• Ceccuzzi, S., Ponti, C., Schettini, G., Ravera, G.L., “On the use of corrugations in mode filters for oversized rectangular waveguides”, IEEE MTT-S International Microwave Symposium Digest, Volume 2016-August, 9 August 2016, Article number 7540276, 2016 IEEE MTT-S International Microwave Symposium, IMS 2016; San Francisco; United States; 22-27 May 2016.

 

• V. Jandieri, R. Khomeriki, G. Schettini, D. Erni, “Nonlinear all-optical digital amplification of light pulses based on coupled photonic crystal guiding nanostructures”, 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA),  7-11 September 2015, Turin, Italy.

 

• S. Ceccuzzi, L. Pajewski, and G. Schettini, “Gain Enhancement of Realistic 3D Antennas by Periodic Dielectric Cylinders: a Comparison between Two Different EBG-based Mechanisms,” Proceedings of Metamaterials 2015, 7-10 September 2015, Oxford.

 

• S. Ceccuzzi, L. Pajewski, and G. Schettini, “Low permittivity EBG materials for antenna superstrates,” IEEE International Symposium on Antennas and Propagation (AP-S 2015), 19-25 July 2015, Vancouver, Canada.

 

• C. Castaldo, A. Di Siena, R. Fedele, F. Napoli, L. Amicucci, R. Cesario, G. Schettini “Influence of collisions on parametric instabilities produced by lower hybrid wave power”, 42nd European Physical Society Conference on Plasma Physics, EPS 2015, 22-26 June 2015, Lisbon, Portugal.

 

• C. Ponti, L. Pajewski, and G. Schettini “The cylindrical-wave approach as a useful tool for defining reference scenarios for inverse and imaging techniques,” IEEE Conference on Antenna Measurements and Applications, (CAMA 2014), Antibes,  16-19 November, 2015.

 

• S. Ceccuzzi, C. Ponti, L. Pajewski, and G. Schettini, “EBG-based spatial filters for directive antennas: a comparison between two different methods,” Proc. XX Riunione Nazionale di Elettromagnetismo (RiNEm), Padova, Italy, 15-18 September 2014.

 

• S. Ceccuzzi, C. Ponti, G. Schettini “On highly-directive EBG-based Antennas,” Proc. of the 2014 International Conference on Electromagnetics in Advanced Applications (ICEAA), Aruba, 3-9 August 2014, pp 121-124.

 

• S. Ceccuzzi, L. Pajewski, and G. Schettini, “Enhancing the Directivity of a Short-Length Horn by an EBG Cavity,” IEEE International Symposium on Antennas and Propagation (AP-S 2014), 6-11 July 2014, Memphis, Tennessee, U.S.A, pp. 1776-1777.

 

• S. Ceccuzzi, C. Ponti, L. Pajewski, and G. Schettini, “On 2D photonic crystals and the shaping of radiation diagrams,” Proc. International Conference on Transparent Optical Networks, 6-10 July 2014, Graz, Austria.

 

• F. Tosti, S. Adabi, L. Pajewski, G. Schettini, A. Benedetto “Large-scale analysis of dielectric and mechanical properties of pavement using GPR and LFWD”, Proceedings of the 15th International Conference on Ground Penetrating Radar, GPR 2014, 30 June – 4 July 2014, Bruxelles, Belgium.

 

• C. Ponti, L. Pajewski, and G. Schettini, “Simulation of scattering by cylindrical targets hidden behind a layer,” Proc.XV International Conference on Ground Penetrating Radar (GPR2014), June 30 - July 4, 2014, Brussels, Belgium.

 

• M.A. Fiaz, C. Ponti, and G. Schettini, “On the scattering by a cylindrical object below a rough surface with the CWA,” Proc. IEEE MTT-S Int. Conf. Num. Electromagn. Mod. and Opt. for RF, Microwave, and Terahertz Applications (NEMO 2014), Pavia, Italy, 14-16 May, 2014.

 

• S. Ceccuzzi, L. Pajewski, C. Ponti, and G. Schettini, “Comparison between Two Methods for Directivity Enhancement of Antennas through 2-D EBGs,” Progress In Electromagnetics Research Symposium Proceedings, Stockholm, Sweden, 12-15 Aug. , 2013, pp. 557-561.

 

• Pajewski, L., Benedetto, A., Derobert, X., (...), Schettini, G., Trinks, I. , “Applications of Ground Penetrating Radar in civil engineering - COST action TU1208”, IWAGPR 2013 - Proceedings of the 2013 7th International Workshop on Advanced Ground Penetrating Radar 2013, Article number 6601528, IWAGPR 2013; Nantes; France; 2-5 July 2013.

 

• S. Ceccuzzi, L. Pajewski, C. Ponti, and G. Schettini, “Comparison Between two Methods for the Directivity Enhancement of Antennas Through 2-D Electromagnetic Bandgap Structures,” 2013 IEEE International Microwave Symposium (IMS) Digest, Seattle, WA, 2-7 June 2013. 

 

• F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “Cylindrical-wave approach for line-source electromagnetic scattering by buried dielectric cylinders,” Proc. of IWAGPR 2013, Nantes, France, 2-5 July 2013.

 

• C. Ponti, F. Frezza, L. Pajewski, and G. Schettini, “Scattering by Buried PEC Cylinders from an Arbitrary 2D Illumination,” Proc. of URSI-EMTS 2013, Hiroshima, Japan, 19-24 May, 2013.

 

• F. Frezza, L. Pajewski, C. Ponti, G. Schettini, and N. Tedeschi, “Plane-Wave Scattering by a Perfectly-Conducting Circular Cylinder Buried in a Lossy Medium,” Proc. XIX Riunione Nazionale di Elettromagnetismo (RiNEm), Rome, Italy, 10-14 September , 2012, pp. 207-2012.

 

• Napoli, F., Castaldo, C., Cesario, R., Schettini, G. “A parametric analysis of nonlinear lower hybrid effects”, Journal of Physics: Conference Series, Volume 401, Issue 1, 2012, Article number 012016, 13th Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas; Varenna; Italy; 27-31 August 2012.

 

• F. Frezza, L. Pajewski, C. Ponti, G. Schettini, and N. Tedeschi, “CWA for Electromagnetic Scattering by Subsurface Targets in a Lossy Medium,” Geophysical Research Abstracts, vol. 14, 2012, 9th European Geosciences Union (EGU) General Assembly, 22-27 April 2012, Vienna, Austria.

 

• Meschino, S., Pajewski, L., Schettini, G., Pastorino, M., Randazzo, A. “Sub-surface localization of buried cylinders by means of sub-array processing”, Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, 2012, Article number 6206193, Pages 1373-1377, 6th European Conference on Antennas and Propagation, EuCAP 2012; Prague; Czech Republic; 26-30 March 2012.

 

• L. Pajewski, C. Ponti, and G. Schettini, "Analysis and Design of Diffractive-Optical and Photonic Band-Gap Elements: Activities during the COST Action MP0702", Proceedings of Micro- and nano-photonic materials and devices MINAP 2012, 16-18 January, 2012, Trento, Italy, pp. 137-140.

 

• L. Pajewski, C. Ponti, G. Schettini e F. Frezza, “Near-field solution to scattering by buried cylindrical targets” Proc. 5^th International Conference on Electromagnetic Near-Field Characterization and Imaging (ICONIC 2011), 30 November – 2 December 2011, Rouen, France.

 

• M. A. Fiaz, L. Pajewski, C. Ponti, G. Schettini, and F. Frezza, “On the scattering by buried objects”, Proc. of 14^th  International Conference on Network-Based Information Systems (NBiS) 2011, 7-9 September 2011, Tirana, Albania, pp. 478-483.

 

• M. A. Fiaz, L. Pajewski, C. Ponti, G. Schettini, and F. Frezza “Scattering by cylindrical targets buried in a ground with rough interface,” Proc. 6^th International Workshop on Advanced Ground Penetrating Radar (IWAGPR2011), 22-24 June 2011, Aachen, Germany, pp. 166-171. 

 

• Benedetto, A., Tosti, F., Schettini, G., Twizere, C. , “Evaluation of geotechnical stability of road using GPR”, 2011 6th International Workshop on Advanced Ground Penetrating Radar, IWAGPR 2011, 2011, Article number 5963858, 2011 6th International Workshop on Advanced Ground Penetrating Radar, IWAGPR 2011; Aachen; Germany; 22-24 June 2011.

 

• Napoli, F., Pajewski, L., Schettini, G., Vescovo, R., “On a multi-objective approach in the non-uniform symmetrical linear antenna array design”, Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011, 2011, Article number 5782015, Pages 2221-2225, 5th European Conference on Antennas and Propagation, EUCAP 2011; Rome; Italy; 10-15 April 2011.

 

• F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, “CWA characterization of buried infrastuctures,” Geophysical Research Abstracts, vol. 13, 2011, 8th European Geosciences Union (EGU) General Assembly, 3-8 April 2011, Vienna, Austria.

 

• L. Di Palma, F. Frezza, L. Pajewski, E. Piuzzi, C. Ponti, G. Rossi, and G. Schettini, “Experimental investigations on woodpile EBG metamaterials,” META2010 – 5th National Workshop on Metamaterials and Special Material for Electromagnetic Applications and TLC, 13-15 December 2010, Roma.

 

• S. Ceccuzzi, S. Meschino, F. Mirizzi, L. Pajewski, C. Ponti, and G. Schettini, “A FEM analysis of microwave components for oversized waveguides,” Quarta giornata di studio italiana: Il metodo degli elementi finiti nelle applicazioni dell’ingegneria elettrica e dell’informazione, 13-15 December 2010, Rome, Italy.

 

• F. Frezza, L. Pajewski, C. Ponti, and  G. Schettini, “Scattering by cylindrical objects buried in a dielectric layer,” Proc. Asia-Pacific Microwave Conference 2010 (APMC 2010), 7-10 December 2010, Pacifico Yokohama, Yokohama, Japan, pp.861-864.