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Autonomic function assessment using analysis of heart rate variability

control ENGINEERING PRACTICE 1997年第12期5卷 1731-1737页

作者： Bates, RA Hilton, MF Godfrey, KR Chappell, MJ BIRMINGHAM HEARTLANDS HOSP DEPT RESP PHYSIOLBIRMINGHAM B9 5SSW MIDLANDSENGLAND

Analysis of changes in heart rate can be useful in determining the state of various body systems. In particular the analysis of heart rate variability (HRV) is used in the assessment of autonomic function. This paper uses the discrete harmonic wavelet transform for a time-frequency analysis of HRV data to show changes in spectral power over time. Signals representing patient heart rate are presented, and methods for spectral and time-frequency analysis are described. Three sets of patient data are then analysed using these methods. The results show the potential of time-frequency analysis in the assessment of medical disorders, such as the sleep apnoea syndrome, where transient alterations in autonomic function occur. Copyright (C) 1997 Elsevier Science Ltd.

关键词： biomedical systems discrete Fourier transforms interpolation sampled data spectral analysis stationarity time-frequency representation

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Sensor validation in biomedical applications

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control ENGINEERING PRACTICE 1997年第12期5卷 1753-1758页

作者： Leahy, MJ Henry, MP Clarke, DW Department of Engineering Science University of Oxford UK

The sensor validation or SEVA project (Henry and Clarke 1991;Henry and Clarke 1993) promotes the use of intelligence in 'smart' sensors and the use of standard metrics to efficiently communicate self-diagnostics to the outside world. The standard metrics describe the status of the sensor including on-line uncertainty and a status flag to describe how the current validated measurement value has been derived. The end result is to provide a compact generic description of the quality of a measurement to the controller, with which decisions as to how to use the measurement can be made. This paper proposes the use of SEVA principles in the interpretation of data from biomedical instrumentation, in order to aid the decision-making process, particularly in critical care. For these purposes the pulse oximeter and polarographic oxygen tension meter will be used as working examples of typical 'intelligent sensors' because they make use of a microprocessor to perform self-diagnostics, as well as implementing measurement algorithms. Copyright (C) 1997 Elsevier Science Ltd.

关键词： sensors medical applications fault detection fault-tolerant systems sensor validation uncertainty

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Neural predictive controller for closed-loop control of glucose using the subcutaneous route: A simulation study

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control ENGINEERING PRACTICE 1997年第12期5卷 1727-1730页

作者： Trajanoski, Z Regittnig, W Wach, P Department of Biophysics Institute of Biomedical Engineering Graz University of Technology Inffeldgasse 18 8010 Graz Austria

The objective of this study was to develop and evaluate a strategy for closed-loop control of glucose using subcutaneous (s.c.) glucose measurement and s.c. infusion of monomeric insulin analogues. The method was based on off-line identification of the glucoregulatory system using neural networks and a nonlinear model predictive controller. Numerical studies on system identification and closed-loop control of glucose were carried out using a comprehensive model of glucose regulation. The proposed control strategy was robust against noise and time delays, and enabled stable control also for slow time variations of the controlled process. In conclusion, closed-loop control of glucose is feasible using the s.c. route and a neural predictive controller. Copyright (C) 1997 Elsevier Science Ltd.

关键词： radial base function networks predictive control nonlinear systems simulation

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modelling, evaluation, and adaptive control of an instrumentation system

Modelling, evaluation, and adaptive control of an instrument...

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3rd IEEE Real-Time Technology and Applications symposium, RTAS 1997

作者： Waheed, Abdul Rover, Diane T. Mutka, Matt W. Smith, Hugh Bakic, Aleksandar Department of Electrical Engineering Michigan State University East Lansing MI 48824 United States Department of Computer Science Michigan State University East Lansing MI 48824 United States

We present results from modeling and evaluating the JEWEL instrumentation system (IS), which is being used for runtime data collection from a distributed, real-time application. Our modeling and evaluation effort addresses two objectives: (1) providing early feedback to the system developers regarding the JEWEL IS configuration options for this application;and (2) evaluation of the design alternatives for an adaptive controller to control the overhead and intrusion of the JEWEL IS to a real-time video conferencing application. For JEWEL IS design, we compare two data collection and forwarding policies (collect-and-forward and batch-and-forward). For the design of the adaptive controller, we compare two adaptation policies (static and dynamic adaptation) and two policies to schedule the implementation of the control decisions (distributed and centralized scheduling). Results reported in this paper indicate that the batch-and-forward policy for IS design static adaptation policy with distributed scheduling for the adaptive controller design meet the domain-specific requirements. © 1997 IEEE.

关键词： Scheduling

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Time domain identification of non-linear systems

Time domain identification of non-linear systems

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Proceedings of the 1995 3rd URSI International symposium on Signals, systems and Electronics, ISSSE'95

作者： Sobhy, M.I. Hosny, E.A. Ng, M.W.R. Bakkar, El-Sayed A. Univ of Kent at Canterbury Kent United Kingdom

A new method of non-linear system design, and non-linear subsystem modeling is presented. The method is based on identifying a non-linear model for each subsystem and combining the individual models to solve the entire system. Time domain modelling and simulation is used throughout the procedure but frequency domain characteristics are also available. modelling of non-linear subsystem is achieved by time domain measurement which offers considerable saving in measurement time. The identified models are not based on equivalent circuits and this offers flexibility and saving in the amount of data stored for each model.

关键词： Nonlinear control systems

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From modelling using function charts for control systems to analysis using Petri nets 3

From modelling using function charts for control systems to ...

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3rd International Workshop on Modeling, Analysis, and Simulation of Computer and Telecommunication systems, MASCOTS 1995

作者： El Rhalibi, A. Prunet, F. Durante, C. LIRMM - Laboratoire d'Informatique Robotique et Micro-éctronique de Montpellier UMR 9928 - Université Montpellier II/CNRS 161 rue ADA Montpellier Cedex 534392 France

ISBN: (纸本)0818669020

A technical process is the controlled flow of matter energy, and/or information. As opposed to the widely investigated continuous control, this paper concentrates on event-related control modelling and validation. In this case, process and related process control can be described by steps and transitions which can be represented very concisely by a Functions Charts for control systems model (Grafcet in French). As it is difficult to validate the Grafcet model we propose to transform a Grafcet in Petri net model that is a rigid mathematical tool and which can be used for a very general approach to event-related process control in design and analysis. © 1995 IEEE.

关键词： Petri nets

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TEMPERATURE-RESPONSIVE POLY(N-ISOPROPYLACRYLAMIDE) AS A MODULATOR FOR ALTERATION OF HYDROPHILIC HYDROPHOBIC SURFACE-PROPERTIES TO control ACTIVATION INACTIVATION OF PLATELETS

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JOURNAL OF controlLED RELEASE 1995年第1-2期36卷 125-133页

作者： OKANO, T KIKUCHI, A SAKURAI, Y TAKEI, Y OGATA, N SOPHIA UNIV FAC SCI & TECHNOLDEPT CHEMCHIYODA KUTOKYO 102JAPAN

Our research is directed toward development and fundamental studies of biomedically relevant modulation systems using the temperature-responsive polymer, poly(N-isopropylacrylamide) (PIPAAm) functionalized with a carboxyl end group, as the switching element. This material has been attached to both biomolecules and solid surfaces to create new, modified bioconjugates and grafted surfaces, respectively. PIPAAm was used to introduce a reversible switching function correlated to hydration-dehydration changes of polymer chains in response to changes in temperature, The introduction of PIPAAm chains onto polymer surfaces is intended to impart temperature-responsive surface property changes, These surfaces were prepared using either PIPAAm with a terminal carboxyl end group or random copolymers of IPAAm with acrylic acid. The effects of graft conformation on the dynamics of grafted PIPAAm species were investigated by means of aqueous dynamic contact angle measurement. Each PIPAAm-grafted surface showed completely hydrophilic nature below 20 degrees C, however, these surfaces become hydrophobic above their critical temperature. The extent of hydrophobic property for multipoint-grafted surfaces was small compared to that of the terminally grafted surface. These hydrophilic/hydrophobic surface property changes affect the platelet contact activation. The increase in cytoplasmic [Ca2+](i) in platelets was observed only when PIPAAm grafted surface become hydrophobic, The feasibility of cell activation/inactivation control by temperature-modulated surface changes is attractive as modulator for biomedical systems and this strategy may lead to development of new 'intelligent materials' with specific temperature-modulated surface properties.

关键词： POLY (N-ISOPROPYLACRYLAMIDE) (PIPAAM) PIPAAM-GRAFTED SURFACE CONTACT ANGLE TEMPERATURE-MODULATED SURFACE PROPERTY CHANGES PLATELET ACTIVATION

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PERFORMANCE EVALUATION OF A PROCESSOR FARM MODEL FOR POWER-SYSTEM STATE-ESTIMATORS ON DISTRIBUTED-MEMORY COMPUTERS

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COMPUTING systems IN ENGINEERING 1994年第4-6期5卷 479-487页

作者： TAMBOURIS, E VANSANTEN, P MARSH, JF BRUNEL UNIV CTR CONTROL ENGNUXBRIDGE UB8 3PHMIDDXENGLAND

In this work we present a preliminary performance and scalability analysis of a distributed state estimator for power systems when run on a massively parallel machine with a 2D mesh interconnection topology. The parallel algorithm is based on the processor farm, or master-slave, programming model which results in additional modelling complexity from process-to-processor mapping, non-trivial communication overhead and extra computation not present in the serial case. The effect of applying sparsity programming techniques further complicates the computational procedure, and hence the performance analysis. Our objective is to investigate the feasibility of the architecture for the algorithm in hand. To achieve it, we derive an accurate performance model, mainly for the communication overhead, and examine the efficiency of the architecture. Furthermore, we use this model to derive the scaling behaviour of the system, i.e. information on how the system performs if we allow the input size to grow as the number of processors increases. The convergence between theoretical estimates and simulation results obtained is also investigated.

关键词： Parallel processing systems

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3rd International symposium on Formal Techniques in Real Time and Fault Tolerance Organized Jointly with Working Group Provably Correct systems, ProCoS 1994

3rd International Symposium on Formal Techniques in Real Tim...

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3rd International symposium on Formal Techniques in Real Time and Fault Tolerance Organized Jointly with Working Group Provably Correct systems, ProCoS 1994

ISBN: (纸本)9783540584681

The proceedings contain 39 papers. The special focus in this conference is on Formal Techniques in Real Time and Fault Tolerance. The topics include: Hybrid verification by exploiting the environment;correctness of real time systems by construction;specifying and verifying fault-tolerant systems;development of hybrid systems;linear duration invariants;a comparison of statecharts variants;a calculus of stochastic systems;verification of an audio control protocol;verifying invariance properties of timed systems with duration variables;predicting logical and temporal properties of real-time systems using synchronized elementary nets;designing and implementing correct real-time systems;specification and refinement of finite dataflow networks � a relational approach;activation-oriented specification of real-time systems;provably correct systems;simulation approach to provably correct hardware compilation;verification methods for the divergent runs of clock systems;fault-tolerant bisimulation and process transformations;testing and refinement for nondeterministic and probabilistic processes;proving safety properties of hybrid systems;a layered real-time specification of a RISC processor;reasoning about durations in metric temporal logic;stepwise development of fault-tolerant reactive systems;derivation of the input conditional formula from a reactive system specification in temporal logic;from physical modelling to compositional models of hybrid systems;specification and transformation of reactive systems with time restrictions and concurrency;specification and verification of controlled systems;towards a duration calculus proof assistant in PVS and a calculus for hybrid sampled data systems.

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From physical modelling to compositional models of hybrid systems 3rd

From physical modelling to compositional models of hybrid sy...

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3rd International symposium on Formal Techniques in Real Time and Fault Tolerance Organized Jointly with Working Group Provably Correct systems, ProCoS 1994

作者： Nadjm-Tehrani, Simin Strömberg, Jan-Erik Dept. of Computer and Information Science Linköping University Sweden Div. of Automatic Control Dept. of Electrical Engineering Linköpmg Unversity LinköpingS-581 83 Sweden

ISBN: (纸本)9783540584681

By a hybrid system we mean a discrete controller in interaction with a physical environment. This paper discusses methodologies for incorporating physically grounded models in representations of hybrid systems. To this end, we study a driver support system, an example which includes unmodelled inputs. We consider models at different levels of abstraction. First, we show that discrete models of the environment can be obtained from the continuous models without losing relevant information. We do this using an analysis of the continuous state space. Dynamic Transition systems (DTS) are used for the modular modelling at this level of abstraction. Next, we consider models using Hybrid Transition systems (HTS). This can be seen as a modular version of timed transition systems ailowing both differential and algebraic equations in each mode. Finally, we comment on expressivity requirements on hybrid formalisms for modelling realistic physical systems. © Springer-Verlag Berlin Heidelberg 1994.

关键词： Hybrid systems

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