@article{MTMT:1359732, title = {Full Characterization of Act-and-wait Control for First-order Unstable Lag Processes}, url = {https://m2.mtmt.hu/api/publication/1359732}, author = {Insperger, Tamás and Wahi, P and Colombo, A and Stépán, Gábor and Di Bernardo, M and Hogan, SJ}, doi = {10.1177/1077546309341135}, journal-iso = {J VIB CONTROL}, journal = {JOURNAL OF VIBRATION AND CONTROL}, volume = {16}, unique-id = {1359732}, issn = {1077-5463}, abstract = {Act-and-wait control is a special case of time-periodic control for systems with feedback delay, where the control gains are periodically switched on and off in order to stabilize otherwise unstable systems. The stability of feedback systems in the presence of time delay is a challenging problem. In this paper, we show that the act-and-wait type time-periodic control can always provide deadbeat control for first-order unstable lag processes with any (large but) fixed value of the time delay in the feedback loop. A full characterization of this act-and-wait controller with respect to the system and control parameters is given based on performance and robustness against disturbances.}, year = {2010}, eissn = {1741-2986}, pages = {1209-1233}, orcid-numbers = {Insperger, Tamás/0000-0001-7518-9774; Stépán, Gábor/0000-0003-0309-2409} } @article{MTMT:2827074, title = {Nonlinear Stability of a Delayed Feedback Controlled Container Crane}, url = {https://m2.mtmt.hu/api/publication/2827074}, author = {Erneux, T. and Kalmár-Nagy, Tamás}, doi = {10.1177/1077546307074245}, journal-iso = {J VIB CONTROL}, journal = {JOURNAL OF VIBRATION AND CONTROL}, volume = {13}, unique-id = {2827074}, issn = {1077-5463}, year = {2007}, eissn = {1741-2986}, pages = {603-616}, orcid-numbers = {Kalmár-Nagy, Tamás/0000-0003-1374-2620} } @article{MTMT:1109894, title = {Continuation of bifurcations in periodic delay-differential equations using characteristic matrices}, url = {https://m2.mtmt.hu/api/publication/1109894}, author = {Szalai, R and Stépán, Gábor and Hogan, SJ}, doi = {10.1137/040618709}, journal-iso = {SIAM J SCI COMPUT}, journal = {SIAM JOURNAL ON SCIENTIFIC COMPUTING}, volume = {28}, unique-id = {1109894}, issn = {1064-8275}, abstract = {In this paper we describe a method for continuing periodic solution bifurcations in periodic delay-differential equations. First, the notion of characteristic matrices of periodic orbits is introduced and equivalence with the monodromy operator is demonstrated. An alternative formulation of the characteristic matrix is given, which can be computed efficiently. Defining systems of bifurcations are constructed in a standard way, including the characteristic matrix and its derivatives. For following bifurcation curves in two parameters, the pseudo-arclength method is used combined with Newton iteration. Two test examples (an interrupted machining model and a traffic model with driver reaction time) conclude the paper. The algorithm has been implemented in the software tool PDDE-CONT.}, year = {2006}, eissn = {1095-7197}, pages = {1301-1317}, orcid-numbers = {Stépán, Gábor/0000-0003-0309-2409} } @inproceedings{MTMT:2836274, title = {A new look at the stability analysis of delay differential equations}, url = {https://m2.mtmt.hu/api/publication/2836274}, author = {Kalmár-Nagy, Tamás}, booktitle = {ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference}, doi = {10.1115/DETC2005-84740}, unique-id = {2836274}, year = {2005}, pages = {817-822}, orcid-numbers = {Kalmár-Nagy, Tamás/0000-0003-1374-2620} } @article{MTMT:2637272, title = {Stability of Linear Time-Periodic Delay-Differential Equations Via Chebyshev Polynomials}, url = {https://m2.mtmt.hu/api/publication/2637272}, author = {Butcher, Eric A. and Ma, Hai-Tao and Bueler, Ed and Averina, Victoria and Szabó, Zsolt}, doi = {10.1002/nme.894}, journal-iso = {INT J NUMER METH ENG}, journal = {INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING}, volume = {59}, unique-id = {2637272}, issn = {0029-5981}, year = {2004}, eissn = {1097-0207}, pages = {895-922}, orcid-numbers = {Szabó, Zsolt/0000-0002-3650-1662} } @article{MTMT:1148732, title = {Semi-discretization method for delayed systems}, url = {https://m2.mtmt.hu/api/publication/1148732}, author = {Insperger, Tamás and Stépán, Gábor}, doi = {10.1002/nme.505}, journal-iso = {INT J NUMER METH ENG}, journal = {INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING}, volume = {55}, unique-id = {1148732}, issn = {0029-5981}, abstract = {The paper presents an efficient numerical method for the stability analysis of linear delayed systems. The method is based on a special kind of discretization technique with respect to the past effect only. The resulting approximate system is delayed and also time periodic, but still, it can be transformed analytically into a high-dimensional linear discrete system. The method is applied to determine the stability charts of the Mathieu equation with continuous time delay. Copyright (C) 2002 John Wiley Sons, Ltd.}, year = {2002}, eissn = {1097-0207}, pages = {503-518}, orcid-numbers = {Insperger, Tamás/0000-0001-7518-9774; Stépán, Gábor/0000-0003-0309-2409} } @article{MTMT:106051, title = {Subcritical Hopf bifurcation in the delay equation model for machine tool vibrations}, url = {https://m2.mtmt.hu/api/publication/106051}, author = {Kalmár-Nagy, Tamás and Stépán, Gábor and Moon, FC}, doi = {10.1023/A:1012990608060}, journal-iso = {NONLINEAR DYNAM}, journal = {NONLINEAR DYNAMICS}, volume = {26}, unique-id = {106051}, issn = {0924-090X}, abstract = {We show the existence of a subcritical Hopf bifurcation in the delay-differential equation model of the so-called regenerative machine tool vibration. The calculation is based on the reduction of the infinite-dimensional problem to a two-dimensional center manifold. Due to the special algebraic structure of the delayed terms in the nonlinear part of the equation, the computation results in simple analytical formulas. Numerical simulations gave excellent agreement with the results.}, year = {2001}, eissn = {1573-269X}, pages = {121-142}, orcid-numbers = {Kalmár-Nagy, Tamás/0000-0003-1374-2620; Stépán, Gábor/0000-0003-0309-2409} } @article{MTMT:106054, title = {Modelling nonlinear regenerative effects in metal cutting}, url = {https://m2.mtmt.hu/api/publication/106054}, author = {Stépán, Gábor}, doi = {10.1098/rsta.2000.0753}, journal-iso = {PHILOS TRANS - R SOC A}, journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A - MATHEMATICAL PHYSICAL & ENGINEERING SCIENCES}, volume = {359}, unique-id = {106054}, issn = {1364-503X}, year = {2001}, eissn = {1471-2962}, pages = {739-757}, orcid-numbers = {Stépán, Gábor/0000-0003-0309-2409} } @inproceedings{MTMT:2836578, title = {Experimental and Analytical Investigation of the Subcritical Instability in Metal Cutting}, url = {https://m2.mtmt.hu/api/publication/2836578}, author = {Kalmár-Nagy, Tamás and Pratt, J R and Davies, M A and Kennedy, M D}, booktitle = {Proceedings of ASME DETC99: The 17th Biennial Conference on Mechanical Vibration and Noise}, doi = {10.1115/DETC99/VIB-8060}, unique-id = {2836578}, year = {1999}, pages = {1721-1729}, orcid-numbers = {Kalmár-Nagy, Tamás/0000-0003-1374-2620} } @inbook{MTMT:1002656, title = {Delay-differential equation models for machine tool chatter}, url = {https://m2.mtmt.hu/api/publication/1002656}, author = {Stépán, Gábor}, booktitle = {Dynamics and Chaos in Manufacturing Processes}, unique-id = {1002656}, year = {1998}, pages = {165-192}, orcid-numbers = {Stépán, Gábor/0000-0003-0309-2409} } @book{MTMT:1002286, title = {Retarded Dynamical Systems. Stability and Characteristic Functions}, url = {https://m2.mtmt.hu/api/publication/1002286}, isbn = {0470213353}, author = {Stépán, Gábor}, publisher = {Longman Scientific & Technical}, unique-id = {1002286}, year = {1989}, orcid-numbers = {Stépán, Gábor/0000-0003-0309-2409} }