Research
Yannis Phillis's research interests include:
a. Stochastic models of unreliable production networks, transfer lines, flexible manufacturing systems, applications of fuzzy logic to manufacturing and queuing.
b. Environmental systems, sustainable development.
Research Contributions:
· He has developed a pioneering model for the analysis and design of production lines and networks of arbitrary geometries and large dimensions. The networks are unreliable and part arrivals and departures are random. The goal is to compute, among others, throughput, inventories, and downtimes and design the network optimally. The accuracy of the model is almost perfect and its computational speed far superior to other existing models. He and his coworkers developed a software package that has been used by Greek companies and the Ford Motor Company in Great Britain. The package has also been exhibited at the International Fair of Thessaloniki, Greece.
This model handles fast dynamics via analysis and slow dynamics via simulation. Until its development practitioners in the field used simulation for daily production planning, which demands hours or even days and, thus, is useless, or analysis which is unacceptably inaccurate. The model has run times of seconds or at most minutes and accuracies ranging above 95%. An executive of Ford Motor, Dagenham, England called this model “miraculous” after they used it in the production of the Jaguar engines.
This work is presented in the book: Kouikoglou and Phillis, “Hybrid Simulation Models of Production Networks,” Kluwer, New York, 2001. The book was very well received by reviewers and peers.
· In the same field of automated and flexible manufacturing engineering, he performed pioneering work by solving two fundamental problems using fuzzy logic, flexibility assessment of complex production systems and flow and routing control of queues. He and his coworkers have again developed practical and user-friendly software packages. The fuzzy methodology was novel in both problems and led to realistic and simple solutions.
· His work on queuing control signals is a ground breaking application of fuzzy logic. Traditional techniques, such as dynamic programming, have limited effectiveness, if at all, in complex or non-Markovian networks. The new methodology on the other hand has already provided solutions to unsolved problems and promises to open a new avenue in queue control.
This work was summarized in the text: Z. Runtong, Y. A. Phillis, and V. S. Kouikoglou, "Fuzzy Control of Queuing Systems," Springer, New York, 2004.
· His latest field of research is the assessment of sustainable development. This is a field of the utmost importance in economics and politics. He has developed a practical mathematical model, which can be used by decision makers and politicians to assess the sustainability of a country or region and detect those aspects that can improve it. Sustainable development is a fashionable term among politicians, economists, and environmentalists, but they all speak of different things. Now, for the first time a framework is developed incorporating a large number of parameters which define and assess sustainability numerically, via fuzzy logic. It can be used to assess the sustainability of an economy and lead to decisions that improve it.
The model is one of the first of its kind in a field where mathematical models were almost absent. A ranking of most countries of the world according to sustainability appears on a regular basis annually in the website www.sustainability.tuc.gr . This material is the basis of courses that he has taught at UCLA, the Technical University of Crete, University of South Florida, and the University of Denver. Numerous researchers have cited and are using the model throughout the world.
This work is presented in the text: Y. A. Phillis, and V. S. Kouikoglou, “Fuzzy Measurement of Sustainability,” Nova Science, New York, 2009.
Scientific books
Fuzzy Measurement of Sustainability, Y. A. Phillis, and V. S. Kouikoglou, Nova Science, New York, 2009.
Fuzzy Control of Queuing Systems, Z. Runtong, Y. A. Phillis, and V. S. Kouikoglou, Springer, New York, 2004.
Hybrid Simulation Models of Production Networks, V. S. Kouikoglou and Y. A. Phillis, Kluwer Academic/Plenum, New York, 2001.
The Greek Environment, Y. A. Phillis, editor of a volume of the Greek Rectors Conference, Savvalas, Athens, 1996.
Research papers
Most recent:
E. Grigoroudis, V. S. Kouikoglou and Y. A. Phillis, "Agricultural sustainability assessment and national policy-making using an axiomatic mathematical model," Environmental and Sustainability Indicators, DOI: 10.1016/j.indic.2024.100401, 2024.
Grigoroudis, V. S. Kouikoglou and Y. A. Phillis, "Allocation of Healthcare Resources in National Health Systems under Climate Change," Circular Economy and Sustainability, DOI: 10.1007/s43615-023-00301-1, 2023.
V. S. Kouikoglou and Y. A. Phillis, "Sensitivity analysis of sustainability indicators using a shifted geometric assessment model," International Journal of Sustainable Development and World Ecology, Vol. 30, No. 8, 938-948, 2023.
Y. A. Phillis, V. S. Kouikoglou, E. Grigoroudis, and F. D. Kanellos, "On a mathematical theory of sustainability assessment," Proceedings of the European Academy of Sciences and Arts, Vol. 1, No. 1, accepted for publication, 2022.
E. Grigoroudis, V. S. Kouikoglou, and Y. A. Phillis, "Transportation sustainability and relevant ranking of European countries," Journal of Intelligent and Robotic Systems, accepted for publication, 2022.
E. Grigoroudis, V. S. Kouikoglou, Y. A. Phillis, and F. D. Kanellos, “Energy sustainability: A definition and assessment model,” Operational Research an International Journal, Vol. 21, No. 3, 1845-1885, 2021.
V. S. Kouikoglou, E. Grigoroudis, and Y. A. Phillis, "National energy sustainability and ranking of countries," Energy Systems Evaluation, Vol. 2, J. Ren Editor, 63-101, Springer, 2021.
E. Grigoroudis, V. S. Kouikoglou, and Y. A. Phillis, “SAFE 2019: Updates and new sustainability findings worldwide,” Ecological Indicators, Vol. 121, https://doi.org/10.1016/j.ecolind.2020.107072, 2021.
J. F. Romero, P. V. Galindo, Y. A. Phillis and E. Grigoroudis, “Graphical sustainability analysis using disjoint biplots,” Operational Research an International Journal, 2020, https://doi.org/10.1007/s12351-020-00573-7
E. Grigoroudis, V. S. Kouikoglou, Y. A. Phillis, and F. D. Kanellos, “Energy sustainability: A definition and assessment model,” Operational Research an International Journal, 2019, https://doi.org/10.1007/s12351-019-00492-2
Υ. Α. Phillis, “Some security issues of living on planet Earth,” Learning to Live Together: Promoting Social Harmony, J. A. Scott Editor, 7-16, Springer, 2019.
E. Grigoroudis, V. S. Kouikoglou, Y. A. Phillis, and F. D. Kanellos, “Energy sustainability: A definition and assessment model,” Operational Research an International Journal, to appear.
Υ. Α. Phillis, “Some security issues of living on planet Earth,” Learning to Live Together: Promoting Social Harmony, J. A. Scott Editor, 7-16, Springer, 2019.
E. Grigoroudis, F. D. Kanellos, V. S. Kouikoglou, and Y. A. Phillis, “The challenge of the Paris Agreement to contain climate change,” Intelligent Automation and Soft Computing, Vol. 24, No. 2, 319-330, 2018.
Y. A. Phillis, N. Chairetis, E. Grigoroudis, F. D. Kanellos, and V. S. Kouikoglou, “Climate security assessment of countries,” Climatic Change, Vol. 148, 25-43, 2018.
Y. A. Phillis, V. S. Kouikoglou, and C. Verdugo, “Urban sustainability and ranking of cities,” Computers, Environment and Urban Systems, Vol.64, 254-265, 2017.
F. D. Kanellos, E. Grigoroudis, C. Hope, V. S. Kouikoglou, and Y. A. Phillis, “Optimal GHG emissions abatement and aggregate economic damages of global warming,” IEEE Systems Journal, Vol. 11, No. 4, 2784-2793, 2017.
E. Grigoroudis, F. D. Kanellos, V. S. Kouikoglou, and Y. A. Phillis, “Optimal abatement policies and related behavioral aspects of climate change,” Environmental Development, Vol. 19, 10-22, 2016
E. Grigoroudis, V. S. Kouikoglou, and Y. A. Phillis, “Energy sustainability of countries,” Handbook of Research on Sustainable Development and Economics, IGI-Global, 96-117, 2015.
E. Grigoroudis, V. S. Kouikoglou and Y. A. Phillis, “SAFE 2013: Sustainability of countries updated,” Ecological Indicators, Vol. 38, 61-66, March, 2014.
Y. A. Phillis, A. M. Madni, E. Grigoroudis, F. Kanellos, V. S. Kouikoglou, and S. Papaefthymiou, “It’s now or never: Why climate action is so urgent,” The Bridge, US National Academy of Engineering, Vol. 44, No. 3, 30-37, Fall 2014.
Y. A. Phillis, “Sustainability,” Encyclopedia of Information Science and Technology, IGI-Global, 6935-6947, 2014.
E. Grigoroudis and Y. A. Phillis, “Modeling healthcare system-of-systems: A mathematical programming approach,” IEEE Systems Journal, Vol. 7, No. 4, 571-580, 2013.
E. Grigoroudis, V. S. Kouikoglou, and Y. A. Phillis, “A fuzzy paradigm for the sustainability evaluation of energy systems,” Assessment and Simulation Tools for Sustainable Energy Systems. Theory and Applications, F. Cavallaro Editor, 205-224, 2013.
Y. A. Phillis and V. S. Kouikoglou, “System-of-Systems hierarchy of biodiversity conservation problems,” Ecological Modeling, Vol. 224, Issue 1, 36-48, 2012.
J. A. Conner, Y. A. Phillis, and V. I. Manousiouthakis, “On a sustainability interval index and its computation through global optimization,” AIChE Journal, Vol. 58, No. 9, 2743-2757, 2012.
Y. A. Phillis and V. S. Kouikoglou, “A System-of-Systems approach to the analysis and conservation of biodiversity,” Enterprise Information Systems, R. Zhang, J. Zhang, Z. Zhang, J. Filipe, and J. Cordeiro Eds, , Vol. 102, 3-15, Springer, 2012.
E. Grigoroudis, V. S. Kouikoglou, and Y. A. Phillis, “Approaches for measuring sustainability,” Global Sustainable Development and Renewable Energy Systems, P. Olla Editor, 101-130, 2012.
V. S. Kouikoglou and Y. A. Phillis, “Application of a fuzzy hierarchical model to the assessment of corporate social and environmental sustainability,” Corporate Social Responsibility and Environmental Management, Vol. 18, No. 4, 209-219, 2011.
Y. A. Phillis, E. Grigoroudis, and V. S. Kouikoglou, “Sustainability ranking and improvement of countries,” Ecological Economics, Vol. 70, No. 3, 542-553, 2011.
Y. A. Phillis, V. S. Kouikoglou, and V. Manousiouthakis, “A review of sustainability models as system of systems,” IEEE Systems Journal, Vol. 4, No. 1, 19-25, 2010.
V. S. Kouikoglou and Y. A. Phillis, “On the monotonicity of hierarchical sum-product fuzzy systems,” Fuzzy Sets and Systems, Vol. 160, Issue 24, 3530-3538, 2009.
Y. A. Phillis and B. J. Davis, "Assessment of corporate sustainability via fuzzy logic," Journal of Intelligent and Robotic Systems, Vol. 55, No. 1, 3-20, 2009.
Y. A. Phillis, V. S. Kouikoglou, and Xiaomin Zhu, "Fuzzy assessment of material recyclability and its applications," Journal of Intelligent and Robotic Systems, Vol. 55, No. 1, 21-38, 2009.
V. Kouloumpis, V. S. Kouikoglou, and Y. A. Phillis, “Sustainability assessment of nations and related decision making using fuzzy logic,” IEEE Systems Journal, Vol.2, No. 2, 224-236, 2008.
Y. A. Phillis, V. Kouloumpis, and V. S. Kouikoglou, “Sustainability ranking and critical sustainability factors of nations,” Ecological Economics Research Trends, C. C. Pertsova Editor, 149-170, Nova Publishers, N.Y. 2008.
S. Ioannidis, V. S. Kouikoglou, and Y. A. Phillis, “Analysis of admission and inventory control policies for production networks,” IEEE Transactions on Automation Science and Engineering, Vol. 5, No. 2, 275-288, 2008.
S. Ioannidis, V. S. Kouikoglou, and Y. A. Phillis, "Coordinating quality, production, and sales in manufacturing systems," International Journal of Production Research, Vol. 42, No 18, 3947-3956, 2004.
L. Andriantiatsaholiniaina, V.S. Kouikoglou, and Y. A. Phillis, "Evaluating strategies for sustainable development: Fuzzy logic reasoning and sensitivity analysis," Ecological Economics, Vol. 48, No 2, 149-172, 2004.
R. Zhang, Y. A. Phillis, and J. Ma, "A Fuzzy approach to the balance of drop and delay priorities in differentiated services networks," IEEE Transactions on Fuzzy Systems, Vol. 11, No 6, 840-846, 2003.
Y. A. Phillis, V. S. Kouikoglou and L.A. Andriantiatsaholiniaina, "Sustainable development: a definition and assessment, " Environmental Engineering and Management Journal, Vol. 2, No. 4, 345-355, December 2003.
R. Zhang and Y. A. Phillis, "Fuzzy assignment of customers for a parallel queueing system with two heterogeneous servers," Journal of Intelligent and Fuzzy Systems, Vol. 11, No. 3,4, 163-169, 2002.
V. S. Kouikoglou and Y. A. Phillis, "Design of product specifications and control policies in a single- stage production system," IIE Transactions, Vol. 34, 591-600, 2002.
Y. A. Phillis and L. Andriantiatsaholiniaina, "Sustainability: An ill-defined concept and its assessment using fuzzy logic," Ecological Economics, Vol. 37, No. 3, 435-456, June 2001.
R. Zhang and Y. A. Phillis, "Admission control and scheduling in simple series parallel networks," IEEE Transactions on Fuzzy Systems, Vol. 9, No. 2, 307-314, April 2001.
R. Zhang and Y. A. Phillis, "Fuzzy control of two-station queueing networks with two types of customers," Journal of Intelligent and Fuzzy Systems, Vol. 8, 27-42, 2000.
Υ. A. Phillis, "Some thoughts about higher education in Greece," IEEE Robotics and Automation Magazine, Vol. 6, No. 2, 64-68, 1999.
R. Zhang and Y. A. Phillis, "Fuzzy control of arrivals to tandem queues with two stations," IEEE Transactions on Fuzzy Systems, Vol.7, No. 3, 361-367, June 1999.
Y. A. Phillis and R. Zhang, "Fuzzy service control of queueing systems," IEEE Transactions on Systems, Man, and Cybernetics, Vol. 29, No. 4, 503-517, 1999.
R. Zhang and Y. A. Phillis, "Fuzzy control of queueing systems with heterogeneous servers," IEEE Transactions on Fuzzy Systems, Vol. 7, No. 1, 17-26, 1999.
N. C. Tsourveloudis and Y. A. Phillis, "Manufacturing flexibility measurement: A fuzzy logic framework," IEEE Transactions on Robotics and Automation, Vol. 14, No. 4, 513-525, 1998.
R. Zhang and Y. A. Phillis, "A fuzzy approach to the flow control problem," Journal of Intelligent and Fuzzy Systems, Vol. 6, No. 4, 447-458, 1998.
N. C. Tsourveloudis and Y. A. Phillis, "Fuzzy assessment of machine flexibility," IEEE Transactions on Engineering Management, Vol. 45, No. 1, 78-87, 1998.
V. S. Kouikoglou and Y. A. Phillis, "Review of a fast simulation method for the analysis of queueing networks," Applied Stochastic Models and Data Analysis, Vol. 13, 73-83, 1997.
Y. A. Phillis, V. S. Kouikoglou, D. Sourlas, and V. Manousiouthakis, "Design of serial production systems using discrete event simulation and nonconvex programming techniques," International Journal of Production Research, Vol. 35, No. 3, 753-766, 1997.
V. S. Kouikoglou and Y. A. Phillis, "A continuous-flow model for production networks with finite buffers, unreliable machines, and multiple products," International Journal of Production Research, Vol. 35, No. 2, 381-397, 1997.
N.C. Tsourveloudis and Y. A. Phillis, "Fuzzy measurement of manufacturing flexibility," Applications of Fuzzy Logic: Towards High Machine Intelligence Quotient Systems, M. Jamshidi Editor, Vol. 7, 201-222, 1997.
Y. A. Phillis and V. S. Kouikoglou, "Analysis of production networks of the finite queue type with breakdowns," IEEE Transactions on Robotics and Automation, Vol. 12, No. 4, 505-515, 1996.
V. S. Kouikoglou and Y. A. Phillis, "An efficient discrete-event model for production networks of general geometry," IIE Transactions, Vol. 27, 32-42, 1995.
V. S. Kouikoglou and Y. A. Phillis, "Discrete event modeling and optimization of production lines with random rates," IEEE Transactions on Robotics and Automation, Vol. 10, No. 2., 153-159, 1994.
N.C. Tsourveloudis, V. S. Kouikoglou, and Y. A. Phillis, "Fuzzy regression for the prediction of Paraquat poisonings in Crete," Systems Analysis Modeling Simulation, Vol. 13, 239-245, 1993.
V. S. Kouikoglou and Y. A. Phillis, "Minimax design of two-state k-out-of-n systems," Applied Stochastic Models and Data Analysis, Vol. 9, 245-250, 1993.
V. S. Kouikoglou and Y. A. Phillis, "Trace bounds on the covariances of continuous-time systems with multiplicative noise," IEEE Transactions on Automatic Control, Vol. AC-38, No. 1, 138- 142, 1993.
Υ. A. Phillis, "Comments on 'A model for determining job throughput times for manufacturing flow line workcells with finite buffers'," International Journal of Production Research, Vol. 30, No. 9, 2229, 1992.
Y. A. Phillis and V. S. Kouikoglou, "Techniques in modeling and control policies for production networks," Control and Dynamic Systems, C. T. Leondes Editor, Vol. 47, 1991.
V. S. Kouikoglou and Y. A. Phillis, "An exact discrete-event model and control policies for production lines with buffers," IEEE Transactions on Automatic Control, Vol. AC-36, No. 5, 515527, 1991.
Υ. Α. Phillis, Optimal estimation and control of discrete multiplicative systems with unknown second order statistics", Journal of Optimization Theory and Applications, Vol. 64, No. 1, 153-168, January 1990.
Y. A. Phillis and V. S. Kouikoglou, "Minimax estimation and control of multiplicative systems," Control and Dynamic Systems, C.T. Leondes Editor, Vol. 31, 93-124, 1989.
Υ. Α. Phillis, "A fixed-point smoothing algorithm for discrete multiplicative systems," Journal of Optimization Theory and Applications, Vol. 62, No. 2, 333-339, August 1989.
Υ. Α. Phillis, "Estimation and control of systems with unknown covariance and multiplicative noise," IEEE Transactions on Automatic Control, Vol. AC-34, No. 10, 1075-1078, 1989.
Υ. Α. Phillis, "Algorithms for systems with multiplicative noise," Control and Dynamic Systems, C. T. Leondes Editor, Vol. 30, part 3, 65-81, Academic Press, 1989.
Υ. Α. Phillis, "A smoothing algorithm for systems with multiplicative noise," IEEE Transactions on Automatic Control, Vol. AC-33, No. 4, 401- 403, 1988.
H. D’ Angelo, M. Caramanis, S. Finger, A. Mavretic, Y. A. Phillis, and E. Ramsden, "Event-driven model of an unreliable production line with storage," International Journal of Production Research, Vol. 26, No. 7, 1173-1182, 1988.
Y. A. Phillis, H. D'Angelo and G. Saussy, "Analysis of series - parallel production systems without buffers," IEEE Transactions on Reliability, Vol. R-35, No. 2, 179-184, 1986.
Υ. A. Phillis, "Controller design of systems with multiplicative noise," IEEE Transactions on Automatic Control, Vol. AC-30, No. 10, 1017-1019, 1985.
Υ. A. Phillis, "Y-stability and stabilization in the mean of discrete-time stochastic systems," International Journal of Control, Vol. 40, No. 1, 159-169, 1984.
Υ. A. Phillis, "Maintenance decision making and throughput rates in unreliable production systems," International Journal of Production Research, Vol. 22, No 1, 149-160, 1984.
Υ. A. Phillis, "Optimal stabilization of stochastic systems," Journal of Mathematical Analysis and Applications, Vol. 94, No. 2, 489-500, 1983.
Υ. A. Phillis, "On the stabilization of discrete linear time-varying stochastic systems," IEEE Transactions on Systems, Man and Cybernetics, Vol. SMC-12, No. 3, 415-417, 1982.
Υ. A. Phillis, "On the rigorous treatment of stability of microwave oscillators," International Journal of Electronics, Vol. 52, No. 3, 275-282, 1982.
Υ. A. Phillis, "Entropy stability of continuous dynamic systems," International Journal of Control, Vol. 35, No. 2, 323-340, 1982.
Υ. A. Phillis, "Time limits in the control of pollution systems," Journal of Theoretical Biology, Vol. 93, No. 3, 541-546, 1981.
Υ. A. Phillis, "Entropy stability of discrete dynamic systems," International Journal of Control, Vol. 34, No. 1, 159-171, 1981.
C. T. Leondes, Y. A. Phillis, and L. Chin, "Method of optimizing the update intervals in hybrid navigation systems," Journal of Guidance and Control, Vol. 2, No. 6, 541-542, 1979.