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Phase space topography and the Lyapunov exponent of electrocorticograms in partial seizures

Brain Topography 1990年第3期2卷 187-201页

作者： Iasemidis, Leonidas D. Chris Sackellares, J. Zaveri, Hitten P. Williams, William J. Bioengineering Program Department of Electrical Engineering and Computer Science United States Epilepsy Program Department of Neurology University of Michigan Ann Arbor 48109-0316 MI 1920 Taubman Center/0316 1500 E. Medical Center Drive United States

Electrocorticograms (ECoG's) from 16 of 68 chronically implanted subdural electrodes, placed over the right temporal cortex in a patient with a right medial temporal focus, were analyzed using methods from nonlinear dynamics. A time series provides information about a large number of pertinent variables, which may be used to explore and characterize the system's dynamics. These variables and their evolution in time produce the phase portrait of the system. The phase spaces for each of 16 electrodes were constructed and from these the largest average Lyapunov exponents (L's), measures of chaoticity of the system (the larger the L, the more chaotic the system is), were estimated over time for every electrode before, in and after the epileptic seizure for three seizures of the same patient. The start of the seizure corresponds to a simultaneous drop in L values obtained at the electrodes nearest the focus. L values for the rest of the electrodes follow. The mean values of L for all electrodes in the postictal state are larger than the ones in the preictal state, denoting a more chaotic state postictally. The lowest values of L occur during the seizure but they are still positive denoting the presence of a chaotic attractor. Based on the procedure for the estimation of L we were able to develop a methodology for detecting prominent spikes in the ECoG. These measures (L^*) calculated over a period of time (10 minutes before to 10 minutes after the seizure outburst) revealed a remarkable coherence of the abrupt transient drops of L^* for the electrodes that showed the inital ictal onset. The L^* values for the electrodes away from the focus exhibited less abrupt transient drops. These results indicate that the largest average Lyapunov exponent L can be useful in seizure detection as well as a discriminatory factor for focus localization in multielectrode analysis. © 1990 Human sciences Press, Inc.

关键词： chaos ECoG epileptogenic focus localization Lyapunov exponents partial epileptic seizures phase space

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Use of computer simulation in the development of an algorithm for analysis of paced electrocardiograms

Use of computer simulation in the development of an algorith...

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computers in Cardiology (CinC)

作者： S.E. Greenhut J.M. Jenkins Bioengineering Program and Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

A computer model of the interaction between heart and artificial pacemaker is developed which simulates a variety of dual-chamber device responses in the context of 25 possible arrhythmia classes. The heart-pacemaker interaction (HPI) model includes specifications of cardiac, pacemaker, and noise distribution parameters which permit random simulation of pacemaker failure. It simulates random pacemaker output, capture, and sensing malfunctions. The model has been used to train an automated, knowledge-based algorithm designed to analyze paced electrocardiograms for pacemaker function and malfunction. By allowing the straightforward simulation of numerous arrhythmia/pacemaker failure scenarios, the model has significantly reduced the amount of clinical testing and therefore the development time otherwise required.< >

关键词： computer simulation Algorithm design and analysis Pacemakers Electrocardiography Rhythm Heart Computational modeling Context modeling Testing Myocardium

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Effects of aging on polyimide: a study of bulk and interface chemistry

Effects of aging on polyimide: a study of bulk and interface...

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IEEE Workshop on Solid-State Sensor and Actuator

作者： M.C. Buncick D.D. Denton Department of Electrical and Computer Engineering and Materials Science Program University of Wisconsin Madison Madison WI USA

An analysis is presented of polyimides (PIs) exposed to heat and humidity stress over long periods. Electron spectroscopy for chemical analysis (ESCA) and Fourier transform infrared (FTIR) spectroscopy were used to investigate the basic physical mechanisms that affect PI when stressed. The results show that changes are confined to a surface layer at the PI-air interface. ESCA data show significant changes at the PI-air interface and that the PI-Si interface remains unchanged. FTIR transmission data indicate that the bulk chemistry is unaffected by such exposure. The surface chemistry is characterized by a significant reduction in the pyromellitic dyanhydride (PMDA) moiety and changes in the bonding of oxygen. There appear to be changes in the imide structure for the PI surface, but the mechanisms of change require further study. This has reliability implications for microelectronic systems using PI as a dielectric.< >

关键词： Aging Polyimides Spectroscopy Infrared spectra Chemistry Humidity Stress Electrons Chemical analysis Fourier transforms

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DPRL: a language for representation of operation and safety maintenance procedures of nuclear power plants 90

DPRL: a language for representation of operation and safety ...

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Proceedings of the 3rd international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 2

作者： Rajiv Bhatnagar D. W. Miller B. K. Hajek B. Chandrasekaran Center for Space Research Massachusetts Institute of Technology Cambridge MA Nuclear Engineering Program The Ohio State University Columbus Ohio Department of Computer and Information Science The Ohio State University Columbus Ohio

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computer simulation of heart-pacemaker interaction

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Journal of Electrocardiology 1990年第SUPPL.期23卷 156-156页

作者： Greenhut, Saul E. MacDonald, Robert S. Jenkins, Janice M. Department of Electrical Engineering Computer Science The University of Michigan Ann Arbor MI United States the Bioengineering Program The University of Michigan Ann Arbor MI United States

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computer-AIDED-DESIGN METHODS FOR PROPELLER FILLET GAUGES

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NAVAL ENGINEERS JOURNAL 1990年第3期102卷 202-208页

作者： ALLEN, DW VINOSKI, WS OVERTON, BA David W. Allen:is a senior computer scientist at the Machinery Technology Division Westinghouse Electric Corporation Large Pa. He received the B.A. degree in mathematics from Grinnell College and the M.S. degree in computer science from the University of Pittsburgh. His career with Westinghouse has been divided between assignments in engineering and computer applications. Mr. Allen has published eight technical papers. He received the George Westinghouse Signature A ward of Excellence for his work on the development of the GAGES computer program for designing propeller gages. He is a member of the Association for Computing Machinery (ACM) and the Institute of Electrical and Electronics Engineers (IEEE). Walter S. Vinoski:is a project engineer at the Machinery Technology Division Westinghouse Electric Corporation Large Pa. and was instrumental in the development of the GAGES computer program. He was awarded the George Westinghouse Signature Award of Excellence for his work on the GAGES program. Mr. Vinoski has six years of marine propulsion system experience specifically with propellers. He earned a B.S. degree in electronics engineering and minored in mathematics at the Ohio Institute of Technology. He is a member of the American Society of Naval Engineers. Bernard A. Overton:graduated from North Carolina Agricultural and Technical State University Greensboro N.C. in 1958 with a B.S. degree in mechanical engineering. Within two years of joining the U.S. Army Mr. Overton was honorably discharged as a first lieutenant. Mr. Overton worked seven years at Philadelphia Naval Shipyard in the following areas: shafting shafting alignment bearing reactions noise and vibration surveys propellers and propeller blade gage designs. In 1967 Mr. Overton transferred to the Navy Engineering Center. He has worked on main propulsion devices such as water jets propellers (both submarine and surface ship) and propeller blade gages. Mr. Overton was responsible for the establishment of the Naval Inspectors Propeller Certif

One of the most complicated forms encountered in engineering design is that of the marine propeller. The complexities arise from the complicated hydrodynamic surfaces of the propeller blades and the complicated manner in which the blades are oriented with and attached to the hub. Where propeller blades are attached to the hub, the blade shape is blended into the shape of the hub. The geometry of this region is particularly complicated. The shape of the blend is called a fillet, and the blending region is called the fillet region. Sheet metal gages conforming to various blade surface contours are used in the manufacture and inspection of propellers. Five different types of gages define the shape of the propeller in different regions. Fillet gages are such gages that define the shape of propeller blades in the fillet region. This paper describes a new computer-aided method for designing fillet gages. Previous methods of fillet gage design required the designer to follow a complicated layout procedure of determining where a particular unfilleted blade contour intersected the hub. The design of the fillet was then done in another layout procedure. Newly developed numerical procedures incorporated in a computer program have reduced the time required to design a complete set of gages (including fillet gages) from up to several weeks to hours.

关键词： Propellers

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computer-SYSTEM ARCHITECTURE CONCEPTS FOR FUTURE COMBAT SYSTEMS

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NAVAL ENGINEERS JOURNAL 1990年第3期102卷 43-62页

作者： ZITZMAN, LH FALATKO, SM PAPACH, JL Dr. Lewis H. Zitzman:is the group supervisor of the Advanced Systems Design Group Fleet Systems Department The Johns Hopkins University Applied Physics Laboratory (JHU/APL). He has been employed at JHU/APL since 1972 performing applied research in computer science and in investigating and applying advanced computer technologies to Navy shipboard systems. He is currently chairman of Aegis Computer Architecture Data Bus and Fiber Optics Working Group from which many concepts for this paper were generated. Dr. Zitzman received his B.S. degree in physics from Brigham Young University in 1963 and his M.S. and Ph.D. degrees in physics from the University of Illinois in 1967 and 1972 respectively. Stephen M. Falatko:was a senior engineering analyst in the Combat Systems Engineering Department Comptek Research Incorporated for the majority of this effort. He is currently employed at ManTech Services Corporation. During his eight-year career first at The Johns Hopkins University Applied Physics Laboratory and currently with ManTech Mr. Falatko's work has centered around the development of requirements and specifications for future Navy systems and the application of advanced technology to Navy command and control systems. He is a member of both the Computer Architecture Fiber Optics and Data Bus Working Group and the Aegis Fiber Optics Working Group. Mr. Falatko received his B.S. degree in aerospace engineering with high distinction from the University of Virginia in 1982 and his M.S. degree in applied physics from The Johns Hopkins University in 1985. Mr. Falatko is a member of Tau Beta Pi Sigma Gamma Tau the American Society of Naval Engineers and the U.S. Naval Institute. Janet L. Papach:is a section leader and senior engineering analyst in the Combat Systems Engineering Department Comptek Research Incorporated. She has ten years' experience as an analyst supporting NavSea Spa War and the U.S. Department of State. She currently participates in working group efforts under Aegis Combat System Doctrin

This paper sets forth computer systems architecture concepts for the combat system of the 2010–2030 timeframe that satisfy the needs of the next generation of surface combatants. It builds upon the current Aegis computer systems architecture, expanding that architecture while preserving, and adhering to, the Aegis fundamental principle of thorough systems engineering, dedicated to maintaining a well integrated, highly reliable, and easily operable combat system. The implementation of these proposed computer systems concepts in a coherent architecture would support the future battle force capable combat system and allow the expansion necessary to accommodate evolutionary changes in both the threat environment and the technology then available to effectively counter that threat. Changes to the current Aegis computer architecture must be carefully and effectively managed such that the fleet will retain its combat readiness capability at all times. This paper describes a possible transition approach for evolving the current Aegis computer architecture to a general architecture for the future. The proposed computer systems architecture concepts encompass the use of combinations of physically distributed, microprocessor-based computers, collocated with the equipment they support or embedded within the equipment itself. They draw heavily on widely used and available industry standards, including instruction set architectures (ISAs), backplane busses, microprocessors, computer programming languages and development environments, and local area networks (LANs). In this proposal, LANs, based on fiber optics, will provide the interconnection to support system expandability, redundancy, and higher data throughput rates. A system of cross connected LANs will support a high level of combat system integration, spanning the major warfare areas, and will facilitate the coordination and development of a coherent multi-warfare tactical picture supporting the future combatant command st

关键词： computer Architecture

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GRAPHICS OF TRUNCATED SINUSOIDS

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computerS & GRAPHICS 1989年第4期13卷 545-547页

作者： RAMESH, SR Computer Science and Technology Program University Visvesvaraya College of Engineering Bangalore-1 India

A variety of beautiful images generated by simple non-iterative real functions are discussed. Explanations for their complicated, chaotic behaviour are given.

关键词： computer Graphics

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ON THE DESIGN OF A SINGLE-KEY-LOCK MECHANISM BASED ON NEWTONS INTERPOLATING POLYNOMIAL

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IEEE TRANSACTIONS ON SOFTWARE engineering 1989年第9期15卷 1135-1137页

作者： LAIH, CS HARN, L LEE, JY Department of Electrical Engineering National Cheng Kung University Tainan Taiwan Republic of China Computer Science and Telecommunications Program University of Missouri Kansas City MO 64110

A new single-key-lock (SKL) mechanism used for implementing the access matrix of the computer protection system is proposed. The key selection is very flexible. The lock values are generated recursively based on the Newton's interpolating polynomial. The insertion of a new user/file into the system can be successfully implemented without recomputing all locks/keys. [ABSTRACT FROM AUTHOR]

关键词： Access control access matrix Newton's interpolation polynomial protection security user-hierarchy

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ELECTRICALLY INDUCED TRANSMISSIVITY MODULATION IN POLYMERIC THIN-FILM FABRY-PEROT ETALONS

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APPLIED OPTICS 1989年第20期28卷 4442-4445页

作者： ELDERING, CA KOWEL, ST KNOESEN, A []The authors are with University of California Davis Department of Electrical Engineering Computer Science Organized Research Program on Polymeric Ultrathin Film Systems Davis California 95616

We report the observation of electrically induced changes in transmissivity in Fabry-Perot devices consisting of spin-cast azo-dye/polymer films deposited between gold mirrors. In poled samples the observed modulation shows a linear dependence on the applied modulating voltage. The ratio of the transmissivity modulation observed using incident transverse magnetic polarization to that observed using transverse electric polarization is used to demonstrate that the electrooptic effect dominates the modulation. This is, to our knowledge, the first reported use of a polymeric thin film linear electrooptic material in a Fabry-Perot structure and demonstrates the use of etalons to enhance electrooptic effects in very thin films.

关键词： Electrooptical effects Electrooptical modulators Materials processing Refractive index Thin film applications Thin films

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