Articles in international peer-reviewed conference proceedings

  1. M. Moltafet, M. Leinonen, and M. Codreanu, “Moment generating function of the AoIin multi-source systems with computation-intensive status updates,” in Proc. IEEE Int. Symp. Inform. Theory, submitted, Melbourne, Victoria, Australia, July 12–20 2021. [preprint]

  2. M. Hatami, M. Jahandideh, M. Leinonen, and M. Codreanu, “Age-aware status update control for energy harvesting IoT sensors via reinforcement learning,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., London, UK, Aug. 31–Sep. 3 2020. [preprint]

  3. M. Moltafet, M. Leinonen, and M. Codreanu, "An exact expression for the average AoI in a multi-source M/M/1 queueing model,’’ in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., London, UK, Aug. 31–Sep. 3 2020. [preprint]

  4. M. Moltafet, M. Leinonen, and M. Codreanu, “Average age of information for a multi-source M/M/1 queueing model with packet management,” in Proc. IEEE Int. Symp. Inform. Theory, Los Angeles, California, USA, Jun.21-26 2020. [preprint]

  5. M. Moltafet, M. Leinonen, and M. Codreanu, “Average age of information in a multisource MM1 queueing model with LCFS prioritized packet management,” in Proc. IEEE INFOCOM, Age of Information Workshop, Toronto, Canada, Jul.6-9 2020. [preprint]

  6. M. Fountoulakis, N. Pappas, M. Codreanu, and A. Ephremides, “Optimal sampling cost in wireless networks with age of information constraints,” in Proc. IEEE INFOCOM, Age of Information Workshop, Toronto, Canada, Jul.6-9 2020. [preprint]

  7. M. Moltafet, M. Leinonen, and M. Codreanu, “Average age of information for a multi-source M/M/1 queueing model with packet management and self-preemption in service,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Volos, Greece, Jun.15-19 2020. [preprint]

  8. M. Leinonen and M. Codreanu, “Quantized compressed sensing via deep neural networks,” in Proc. 6G Wireless Summit, Levi, Finland, Mar.17-20 2020. [preprint]

  9. M. Moltafet, M. Leinonen, and M. Codreanu, “An approximate expression for the average AoI in a multi-source M/G/1 queueing model,” in Proc. 6G Wireless Summit, Levi, Finland, Mar.17-20 2020. [preprint]

  10. M. Moltafet, M. Leinonen, M. Codreanu, and N. Pappas, “Power minimization in wireless sensor networks with constrained AoI using stochastic optimization,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, Nov.3-6 2019. [preprint]

  11. M. Hatami, M. Leinonen, and M. Codreanu, “Online caching policy with user preferences and time-dependent requests: A reinforcement learning approach,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, Nov.3-6 2019. [preprint]

  12. M. Moltafet, M. Leinonen, and M. Codreanu, “Worst case analysis of age of information in a shared-access channel,” in Proc Int. Symp. on Wireless Commun. Syst., Oulu, Finland, Aug.27-30 2019. [preprint]

  13. M. Moltafet, M. Leinonen, and M. Codreanu, “Closed-form expression for the average age of information in a multi-source MG1 queueing model,” in Proc. IEEE Inform. Theory Workshop, Visby, Gotland, Sweden, Aug.25-28 2019. [preprint]

  14. M. Leinonen, M. Codreanu, and M. Juntti, “Practical compression methods for quantized compressed sensing,” in Proc. IEEE INFOCOM, SMILING Workshop, Paris, France, Apr. 29 - May 2 2019. [preprint]

  15. M. Leinonen, M. Codreanu, and M. Juntti, “Signal reconstruction performance under quantized noisy compressed sensing,” in Proc. Data Compression Conference, Snowbird, UT, USA, Mar. 26-29 2019.

  16. M. Jahandideh, M. Moltafet, M. Codreanu, and M. Latva-aho, “Low complexity sparse channel estimation for wideband mmWave systems: Multi-stage approach,” in Proc. IEEE Wireless Commun. and Networking Conf., Marrakech, Morocco, Apr. 15-19 2019. [preprint]

  17. M.U. Aminu, M. Codreanu, and M. Juntti, “Bayesian learning based millimeter-wave sparse channel estimation with hybrid antenna arrays,” in Proc. IEEE Works. on Sign. Proc. Adv. in Wirel. Comms., Kalamata, Greece, Jun. 25-28 2018.

  18. U. L. Wijewardhana, M. Codreanu, “Lapped transforms based image recovery for block compressed sensing,” in Proc. Data Compression Conference, Snowbird, UT, USA, Mar. 27-30 2018.

  19. K.B.S. Manosha, S. Joshi, M. Codreanu, N. Rajatheva, and M. Latva-aho, “A distributed admission control algorithm for multicell MISO downlink systems,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Oct. 29 - Nov. 1 2017.

  20. U. L. Wijewardhana, E. Belyaev, M. Codreanu, and M. Latva-aho, “Signal recovery in compressive sensing via multiple sparsifying bases,” in Proc. Data Compression Conference, Snowbird, UT, USA, Apr. 4-7 2017.

  21. S. Joshi, S. Manosha, M. Codreanu, and M. Latva-aho, “Inter-operator dynamic spectrum sharing: A stochastic optimization approach,” in Proc. Wireless On-demand Network systems and Services Conference, Jackson Hole, Wyoming, USA, Feb. 21-24 2017.

  22. U. Wijewardhana, M. Codreanu, M. Latva-aho, “Bayesian method for image recovery from block compressive sensing,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 6-9 2016.

  23. M. Leinonen, M. Codreanu, M. Juntti, and G. Kramer, “Rate-distortion lower bound for compressed sensing via conditional remote source coding,” in Proc. IEEE Inform. Theory Workshop, Cambridge, UK, Sep. 11-14 2016.

  24. M. Leinonen, M. Codreanu, and M. Juntti, “Distributed variable-rate quantized compressed sensing in wireless sensor network,” in Proc. IEEE Signal Proc. for Wireless Commun., Edinburgh, Scotland, Jul. 3-7 2016.

  25. M. Leinonen, M. Codreanu, and M. Juntti, “Channel-robust compressed sensing via vector pre-quantization in wireless sensor networks,” in Proc. IEEE Global Conf. on Signal and Inform. Proc., Orlando, Florida, USA, Dec. 14-16 2015, pp. 383-387.

  26. S. Joshi, U. Wijewardhana, M. Codreanu, and M. Latva-aho, “Maximization of worst-case weighted sum-rate for MISO downlink systems with channel uncertainty,” in Proc. IEEE Int. Conf. Commun., London, UK, Jun. 8-12 2015, pp. 2289-2294.

  27. U. Wijewardhana, M. Codreanu, “A sparse Bayesian learning method for streaming signal recovery,” in Proc. IEEE Inform. Theory Workshop, Hobart, Tasmania, Australia, Nov. 2-5 2014, pp. 302-306.

  28. U. Wijewardhana, M. Codreanu, “Streaming signal recovery using sparse Bayesian learning,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 2-5 2014, pp. 1225-1230.

  29. M. Costa, M. Codreanu, and A. Ephremides, “Age of information with packet management,” in Proc. IEEE Int. Symp. Inform. Theory, Honolulu, HI, USA, Jun. 29-Jul. 4 2014, pp. 1583-1587.

  30. D. Das, A. Abouzeid, and M. Codreanu, “Opportunistic scheduling and relaying in a cooperative cognitive network,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Hammamet, Tunisia, May 12-16 2014.

  31. M. Leinonen, M. Codreanu, and M. Juntti, “Compressed acquisition and progressive reconstruction of multi-dimensional correlated data in wireless sensor networks,” in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, Florence, Italy, May. 4-9 2014, pp. 6449-6453.

  32. D. Das, A. Abouzeid, and M. Codreanu, “Scheduling in cooperative cognitive radio networks,” in Proc. Annual Allerton Conf. Commun., Cont., Computing, Allerton House, UIUC, Illinois, USA, October 2-3 2013, pp. 739-746.

  33. M. Leinonen, M. Codreanu, and M. Juntti, “Distributed correlated data gathering in wireless sensor networks via compressed sensing,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 3-6 2013.

  34. U. Wijewardhana, S. Joshi, M. Codreanu, and M. Latva-aho, “Worst-case weighted sum-rate maximization for MISO downlink systems with imperfect channel knowledge,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 3-6 2013, pp. 1248-1252.

  35. S. Manosha, S. Joshi, M. Codreanu, N. Rajatheva, and M. Latva-aho, “Powerthroughput tradeo in MIMO heterogeneous networks,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 3-6 2013, pp. 1228-1232.

  36. J. Jeon, A. Ephremides, M. Codreanu, and M. Latva-aho, “On hybrid access for cognitive radio systems with time-varying connectivity,” in Proc. IEEE Int. Symp. Inform. Theory, Istanbul, Turkey, July 7-12 2013.

  37. K. Lähetkangas, M. Codreanu, and B. Aazhang, “Energy efficient power allocation for MIMO multihop networks,” in Proc. IEEE Int. Symp. Inform. Theory, Istanbul, Turkey, July 7-12 2013.

  38. U. Wijewardhana, M. Codreanu, and M. Latva-aho, “Robust beamformer design for underlay cognitive radio network using worst case optimization,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Tsukuba Science City, Japan, May 13-17 2013, pp. 404-411.

  39. S. Joshi, M. Codreanu, and M. Latva-aho, “Distributed SINR balancing for MISO downlink systems via the alternating direction method of multipliers,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Tsukuba, Japan, May 13-17 2013, pp. 318-325.

  40. J. Jeon, M. Codreanu, M. Latva-aho, and A. Ephremides, “Sensitivity of stable rates in cognitive radio systems to the sensing errors,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Tsukuba Science City, Japan, May 13-17 2013.

  41. M. Leinonen, M. Codreanu, and M. Juntti, “Consensus based distributed joint power and routing optimization in wireless sensor networks,” in Proc. IEEE Global Telecommun. Conf., Anaheim, California, USA, Dec. 3-7 2012.

  42. S. Joshi, M. Codreanu, and M. Latva-aho, “Distributed resource allocation for MISO downlink systems via the alternating direction method of multipliers,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 4-7 2012, pp. 488-493.

  43. M. Leinonen, M. Codreanu, and M. Juntti, “Distributed consensus based joint resource and routing optimization in wireless sensor networks,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, California, USA, Nov. 4-7 2012.

  44. P. C. Weeraddana, M. Codreanu, S. Joshi, and M. Latva-aho, “Multicell downlink weighted sum-rate maximization: A distributed approach,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 6-9 2011, pp. 1569-1573.

  45. S. Joshi, P. C. Weeraddana, M. Codreanu, and M. Latva-aho, “Weighted sum-rate maximization for MISO downlink cellular networks via branch and bound,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 6-9 2011, pp. 1569-1573.

  46. A. P. Kumara T. G., N. Rajatheva, and M. Codreanu, “Resource allocation for OFDMA-based relay assisted two-tier femtocell networks,” in Proc. IEEE Int. Symp. Wireless Commun. Syst., Aachen, Germany, Nov. 6-9 2011, pp. 834-838.

  47. M. Codreanu, P. C. Weeraddana, M. Latva-aho, and A. Ephremides, “Weighted sumrate maximization in singlecast and multicast wireless networks - global optimum via branch and bound,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., Toronto, Canada, Sept. 11-14 2011, pp. 2274-2278.

  48. P. C. Weeraddana, M. Codreanu, M. Latva-aho, and A. Ephremides, “Optimal maxweight scheduling in a multihop wireless network via branch and bound,” in Proc. IEEE Int. Symp. Inform. Theory, Saint Petersburg, Russia, July 31-Aug. 5 2011, pp. 2787-2791.

  49. P. C. Weeraddana, M. Codreanu, M. Latva-aho, and A. Ephremides, “Weighted sum-rate maximization for a set of interfering links via branch and bound,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 7-10 2010.

  50. J. Karjalainen, M. Codreanu, A. Tölli, M. Juntti, and T. Matsumoto, “On greedy methods for exit chart based transmission power allocation,” in Proc. IEEE Global Telecommun. Conf., Miami, Florida, Dec.6-10 2010.

  51. P. C. Weeraddana, M. Codreanu, M. Latva-aho, and A. Ephremides, “The benefits from simultaneous transmission and reception in wireless networks,” in Proc. IEEE Inform. Theory Workshop, Dublin, Ireland, Aug. 30-Sept. 3 2010, pp. 1-5.

  52. P. C. Weeraddana, M. Codreanu, M. Latva-aho, and A. Ephremides, “Resource allocation for cross-layer utility maximization in multi-hop wireless networks in the presence of self interference,” in Proc. Int. Symp. on Modelling and Opt. in Mobile, Ad-hoc and Wireless Networks, Avignon, France, May 31-June 4 2010, pp. 70-75.

  53. P. C. Weeraddana, M. Codreanu, and M. Latva-aho, “Cross-layer resource allocation for wireless networks via signomial programming,” in Proc. IEEE Global Telecommun. Conf., Honolulu, Hawaii, USA, Nov. 30-Dec. 4 2009, pp. 1-6.

  54. M. Codreanu, P. C. Weeraddana, and M. Latva-aho, “Cross-layer utility maximization subject to stability constraints for multi-channel wireless networks,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Nov. 2-4 2009, pp. 776-780.

  55. P. C. Weeraddana, M. Codreanu, and M. Latva-aho, “On the advantages of using multiuser receivers in wireless ad-hoc networks,” in Proc. IEEE Veh. Technol. Conf., Anchorage, Alaska, USA, Sept. 20-23 2009, pp. 1-6.

  56. M. E. R. Khan, M. Latva-aho, and M. Codreanu, “Performance of interference avoidance scheme for cognitive femtocells in future generation wireless networks,” in M. Codreanu List of publications 8 of 11 Proc. Int. Symp. Wireless Pers. Multimedia Commun., Sendai, Japan, Sept.7-10 2009, CD-Rom.

  57. J. Karjalainen, A. Tölli, M. Codreanu, M. Juntti, and T. Matsumoto, “Power allocation for irregularly modulated MIMO signaling with iterative frequency domain detector,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, California, Nov.1-4 2009, pp. 1518-1522.

  58. P. C. Weeraddana, L. Wei, M. Codreanu, and M. Latva-aho, “Weighted sum-rate maximization for downlink OFDMA systems,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, CA, USA, Oct. 27-29 2008, pp. 990-994.

  59. M. Codreanu, A. Tölli, M. Juntti, and M. Latva-aho, “Uplink-downlink SINR duality via Lagrange duality,” in Proc. IEEE Wireless Commun. and Networking Conf., Las Vegas, Nevada, USA, Mar.31 - Apr. 3 2008, pp. 1160-1165.

  60. P. C. Weeraddana, L. Wei, M. Codreanu, and M. Latva-aho, “Adaptive subcarrier and power allocation for OFDMA systems,” in Proc. of the IFIP Wireless Days Conf., Dubai, UAE, Nov. 24-27 2008, pp. 1-5.

  61. P. C. Weeraddana, M. Codreanu, Li. Wei, and M. Latva-aho, “Low complexity adaptive subcarrier and power allocation scheme for downlink OFDMA systems,” in Proc. Int. Symp. Wireless Pers. Multimedia Commun., Lapland, Finland, Sept. 8-11 2008, CD-Rom.

  62. A. Tölli, M. Codreanu, and M. Juntti, “Linear cooperative multiuser MIMO transmission with quality of service constraints,” in Proc. IEEE Global Telecommun. Conf., Washington, DC, USA, Nov. 30 - Dec. 4 2007, pp. 3285-3289.

  63. M. Codreanu, A. Tölli, M. Juntti, and M. Latva-aho, “Linear transceiver design for SINR balancing in MIMO downlink channels,” in Proc. Int. Conf. on Commun. and Networking in China, Shanghai, China, Aug.22-24 2007.

  64. A. Tölli, M. Codreanu, and M. Juntti, “Linear multiuser MIMO transceiver optimization in cooperative networks,” in Proc. Int. Conf. on Commun. and Networking in China, Shanghai, China, Aug.22-24 2007.

  65. M. Codreanu, A. Tölli, M. Juntti, and M. Latva-aho, “Joint design of Tx-Rx beamformers in MIMO downlink channel,” in Proc. IEEE Int. Conf. Commun., Glasgow, Scotland, June24-28 2007, pp. 4997-5002.

  66. A. Tölli, M. Codreanu, andM. Juntti, “Linear cooperative multiuser MIMO transceiver design with per BS power constraints,” in Proc. IEEE Int. Conf. Commun., Glasgow, Scotland, UK, June 24-28 2007, pp. 4991-4996.

  67. M. Codreanu, A. Tölli, M. Juntti, and M. Latva-aho, “MIMO downlink weighted sum rate maximization with power constraints per antenna groups,” in Proc. IEEE Veh. Technol. Conf., Dublin, Ireland, Apr.23-25 2007, pp. 2048-2052.

  68. A. Tölli, M. Codreanu, and M. Juntti, “Minimum SINR maximization for multiuser MIMO downlink with per BS power constraints,” in Proc. IEEE Wireless Commun. and Networking Conf., Hong Kong, Mar.11-15 2007, pp. 1144-1149.

  69. M. Codreanu, M. Juntti, and M. Latva-aho, “On the dual decomposition based sum capacity maximization for vector broadcast channel,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, California, Oct. 29 - Nov. 1 2006, pp. 468-472.

  70. M. Codreanu, A. Tölli, M. Juntti, and M. Latva-aho, “Weighted sum mean square error minimization in MIMO broadcast channel,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., Helsinki, Finland, Sept.11-14 2006. M. Codreanu List of publications 9 of 11

  71. A. Tölli, M. Codreanu, and M. Juntti, “Soft handover in adaptive MIMO-OFDM cellular system with cooperative processing,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., Helsinki, Finland, Sept.11-14 2006.

  72. A. Tölli, M. Codreanu, and M. Juntti, “Adaptive MIMO-OFDM cellular system with soft handover between distributed base station antennas,” in Proc. IEEE Global Telecommun. Conf., San Francisco, USA, Nov.27 - Dec. 1 2006. 70. M. Codreanu, M. Juntti, and M. Latva-aho, “Low complexity iterative algorithm for finding the MIMO-OFDM broadcast channel sum capacity,” in Proc. Annual Asilomar Conf. Signals, Syst., Comp., Pacific Grove, California, Oct. 28 - Nov. 1 2005, pp. 1529-1533.

  73. M. Codreanu, D. Tujkovic, and M. Latva-aho, “Adaptive MIMO-OFDM systems with estimated channel state information at TX side,” in Proc. IEEE Int. Conf. Commun., Seoul, Korea, May 16-20 2005, vol. 4, pp. 2645-2649.

  74. A. Tölli, M. Codreanu, and M. Juntti, “Suppression of non-reciprocal interference in adaptive MIMO-OFDM cellular systems,” in Proc. IEEE Veh. Technol. Conf., Stockholm, Sweden, May30 - June 1 2005, vol. 2, pp. 1072-1076.

  75. A. Tölli, M. Codreanu, and M. Juntti, “System level impact of non-reciprocal interference in adaptive MIMO-OFDM cellular systems,” in Proc. IST Mobile & Wireless Telecommun. Summit, Dresden, Germany, June 19-23 2005.

  76. M. Codreanu, D. Tujkovic, and M. Latva-aho, “Compensation of channel state estimation errors in adaptive MIMO-OFDM systems,” in Proc. IEEE Veh. Technol. Conf., Los Angeles, California, Sept. 26-29 2004, vol. 3, pp. 1580-1584.

  77. M. Codreanu, D. Tujkovic, and M. Latva-aho, “Adaptive MIMO-OFDM with low signalling overhead for unbalanced antenna systems,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., Barcelona, Spain, Sept. 5-8 2004, vol. 4, pp. 2382- 2386.

  78. A. Tölli and M. Codreanu, “Compensation of interference non-reciprocity in adaptive TDD MIMO-OFDM systems,” in Proc. IEEE Int. Symp. Pers., Indoor, Mobile Radio Commun., Barcelona, Spain, Sept. 5-8 2004, vol. 2, pp. 859-863.

  79. A. Tölli and M. Codreanu, “A closed-loop method for interference non-reciprocity compensation in adaptive TDD MIMO-OFDM systems,” in Mobile Venue 2004 Radio Network Management, Athens, Geece, May 27-28 2004.

  80. M. Codreanu and M. Latva-aho, “Comparison between space-time block coding and eigen-beamforming in TDD MIMO-OFDM downlink with partial CSI knowledge at the TX side,” in Proc. Int. Workshop Multi-Carrier Spread-Spectrum, Oberpfaffenhofen, Germany, Sept. 17-19 2003, pp. 363-370.

  81. R. Tesi, M. Codreanu, and I. Oppermann, “Effects of the interference of UWB transmission in OFDMcommunication systems,” in Proc. 2003 International Workshop on Ultra Wideband, Oulu, Finland, June2-5 2003, CD-Rom.

  82. C. Negrescu, D. Stanomir, M. Codreanu, and I. Constantin, “Simulation results for an improved analytic expression of the bit error rate for the direct sequence spread spectrum receiver equipped with wiener interference rejection filter,” in Proc. IEEE Mediterranean Electrotechnical Conference, Tel-Aviv, Israel, May18-20 1998, pp. 839- 843.

  83. V. E. Neagoe and M. Codreanu, “A neuro-genetic approach for detection of FSK signals,” in Proc. of Int. Conf. “Communications’98”, Bucharest, Romania, Nov.19- 20 1998, pp. 99-104.

  84. C. Negrescu, D. Stanomir, and M. Codreanu, “Validation by simulation of an improved analytic expression for bit error rate in a direct sequence spread spectrum receiver equipped with Wiener filter for interference rejection,” in Proc. of International Symposium on Signal Circuits and Systems, Iasi, Romania, Oct.2-3 1997, pp. 89-92.

  85. A. Petrescu, C. Negrescu, and M. Codreanu, “Neural narrowband filter for interference canceling in direct sequence spread spectrum communications,” in Proc. of 28'th Session of Scientific Communications with International Participations, Technical Military Academy, Iasi, Romania, Nov.13-14 1997, pp. 275-280.