143 results found
Istepanian RSH, 1999, Hybrid signal processing technologies for next generation wireless telemedicine systems, Pages: 33-37
Recently, there was a rapidly growing commercial market for digital mobile telephones and the adoption of the relevant digital cellular standards within the current generation of wireless standards. Thus, wireless and mobile telemedicine systems were currently having a powerful impact the way different healthcare organizations were delivering healthcare to their customers. Telemedicine which was broadly defined as the use of telecommunication infrastructures to provide medical information and health care delivery at a distant and was an emerging field in health care that could have revolutionary impact on the delivery of medical care world-wide.
Istepanian RSH, Petrosian A, Chen S, 1999, Application of wavelet-based ECG data compression for a wireless telecardiology system, ISSN: 0589-1019
This paper presents a new wavelet based ECG compression algorithm compatible for mobile telecardioloy applications. The compression results on three standard segments of clinical ECG data using different wavelet transforms complemented with scalar quantization and Huffman coding procedures suitable for GSM cellular design are presented. The compression results show the compatibility of the compression method for ECG monitoring especially for emergency scenarios and mobile telemedical application.
Chen S, Wu J, Istepanian RH, et al., 1999, Optimizing stability bounds of finite-precision PID controller structures, IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 44, Pages: 2149-2153, ISSN: 0018-9286
Chen S, Wu J, Istepanian RH, et al., 1999, Optimising stability bounds of finite-precision controller structures for sampled-data systems in the delta-operator domain, IEE PROCEEDINGS-CONTROL THEORY AND APPLICATIONS, Vol: 146, Pages: 517-526, ISSN: 1350-2379
Wu J, Istepanian RH, Chen S, 1999, Stability issues of finite-precision controller structures for sampled-data systems, INTERNATIONAL JOURNAL OF CONTROL, Vol: 72, Pages: 1331-1342, ISSN: 0020-7179
Istepanian RS, 1999, Telemedicine in the United Kingdom: current status and future prospects., IEEE Trans Inf Technol Biomed, Vol: 3, Pages: 158-159, ISSN: 1089-7771
The objective of this correspondence is to present an overview of some of the current development and some of the ongoing telemedicine programs in the United Kingdom. The issues of the future integration of telemedicine activities within the National Health Service that promises better access to healthcare with higher efficiency, mobility, and lower cost are also discussed.
Istepanian RSH, Whidborne JF, 1999, Multi-objective design of finite word-length controller structures, Pages: 61-68
Feedback controller implementations with fixed-point arithmetic offer the advantages of speed, memory space, cost and simplicity compared to floating-point arithmetic. Thus, to date, fixed-point processors dedicated for digital controller implementations are still the dominant architecture in many modern digital control engineering applications, particularly for automotive, consumer, military and medical applications. However, most control design methodologies assume that the designed controller will be implemented with infinite precision. Thus, when the controller is implemented on a fixed-point platform, rounding errors can cause a performance degradation and even instability. Hence, there is a trade-off between the cost of the controller in terms of word-length, memory and computation requirements (the controller compactness) and the performance of the system. This paper presents an approach to designing finite word-length feedback controller structures by means of a multi-objective genetic algorithm. The approach provides a set of solutions that are (near) Pareto optimal with respect to minimal word-length and memory requirements and to closed-loop performance. The method is applied to the design of finite word-length controller structures for two examples, a PID controller for a rolling strip mill, and a controller for the IFAC93 benchmark problem. © 1999 IEEE.
Chen S, Istepanian RH, Luk BL, 1999, Signal processing applications using adaptive simulated annealing, Pages: 842-849
Many signal processing applications pose optimization problems with multimodal and nonsmooth cost functions. Gradient methods are ineffective in these situations. The adaptive simulated annealing (ASA) offers a viable optimization tool for tackling these difficult nonlinear problems. We demonstrate the effectiveness of the ASA using three applications, infinite-impulse-response (IIR) filter design, maximum likelihood (ML) joint channel and data estimation and evaluation of minimum symbol-error-rate (MSER) decision feedback equalizer (DFE). © 1999 IEEE.
Istepanian RH, Woodward B, Balos PA, et al., 1999, The comparative performance of mobile telemedical systems based on the IS-54 and GSM cellular telephone standards., J Telemed Telecare, Vol: 5, Pages: 97-104, ISSN: 1357-633X
The performance of mobile telemedical communications links based on the IS-54 and GSM cellular telephone standards (the most widely used commercial systems in North America and Europe, respectively) was studied by computer simulations. A photoplethysmography signal was used to investigate the transmission of medical data over simulated mobile phone channels. Various conditions were simulated in the communications path between a mobile transmitter and receiver, from perfect to distorted conditions. The results showed successful transmission, with bit error rates of better than 10(-7) at the receiver for the IS-54 standard. The performance of the IS-54 standard was superior to that of GSM in terms of minimum path delay variations, especially in built-up (urban) areas.
Chen S, Istepanian RH, Whidborne JF, et al., 1998, Adaptive Simulated Annealing for Designing Finite-Precision PID Controller Structures, IEE Colloquium (Digest), ISSN: 0963-3308
Many control applications pose optimisation problems with multimodal and nonsmooth cost functions. Gradient methods are ineffective in these situations. The adaptive simulated annealing (ASA) offers a viable optimisation tool for tackling these difficult constrained optimisation problems. We demonstrate the effectiveness of the ASA using an application, designing finite-precision PID controller structures with maximum stability robustness measure. The sparseness issue of controller structures is also discussed, and it is shown that the ASA can cope with this kind of constraints easily.
Economopoulos SA, Hadjileontiadis LJ, Istepanian RH, et al., 1998, Robust ECG coding using wavelet analysis and higher-order statistics, IEE Colloquium (Digest), ISSN: 0963-3308
An enhanced method for ECG transmission under ambulatory conditions, based on wavelet transform (WT) and higher-order statistics (HOS) is presented in this paper.
Istepanian RH, Wu J, Chu J, et al., 1998, Maximizing lower bound stability measure of finite precision PID controller realizations by nonlinear programming, Pages: 2596-2600, ISSN: 0743-1619
This paper introduces a new lower bound stability measure with Finite-Word-Length (FWL) considerations that provides a larger measure than existing bounds and gives a better estimation of the stability robustness of sampled data system with FWL controller implementations. The optimal realization problem of the digital PID controller with FWL considerations is addressed. This parameterization problem is formulated as a nonlinear programming problem with a maximum of four independent variables. A strategy based on Rosenbrock's hill climbing algorithm to solve the optimal realization problem of digital PID realizations is developed, and the methodology is applied to a steel rolling mill to illustrate the effectiveness of the new measure. © 1998 AACC.
Habib Istepanian RS, Wu J, Whidborne JF, et al., 1998, Finite word length stability issues of a teleoperation motion-scaling control system, Pages: 1676-1681, ISSN: 0537-9989
In this paper we study the finite-precision implementation and the relevant stability conditions for optimal controller structures of a bilateral motion-scaling teleoperation control system. The parameterized digital controller realizations and the relevant stability robustness measures subject to word length constraints are formulated. The resulting controller structure provide an improved stability condition with minimum finite word length implementation.
He Z, Chen S, Luk B, et al., 1998, Postprocessing for image coding applications using neural network visual model, 8th IEEE Workshop on Neural Networks for Signal Processing, Publisher: IEEE, Pages: 557-566
Whidborne JF, Habib Istepanian RS, Njabeleke I, et al., 1998, Optimal digital controller structure for a fluid power system subject to wordlength constraints, Pages: 146-151, ISSN: 0537-9989
The implementation of a digital H∞-optimal controller for a fluid power system subject to Finite Word Length (FWL) is considered. The paper addresses the digital controller structure problem using an approach based on structured perturbation theory in the l1framework. The resulting controller structure reduces by six orders of magnitude the controller parameter precision which is sufficient for stable FWL implementation.
Istepanian RSH, Li G, Wu J, et al., 1998, Analysis of sensitivity measures of finite-precision digital controller structures with closed-loop stability bounds, IEE Proceedings: Control Theory and Applications, Vol: 145, Pages: 472-478, ISSN: 1350-2379
The problem of digital controller structures and the effect of finite-word-length (FWL) implementation on the closed-loop stability of digital feedback control systems is addressed. A framework is presented to derive two lower stability bounds for a closed-loop system, which are controller structure dependent, and then to solve the optimal FWL controller structure problem by maximising one of these lower bounds. This yields an improved method to design optimal finite-precision controller structures with better numerical accuracy and closed-loop stability characteristics. Comparisons using numerical examples from two digital controller structures demonstrate that the procedure proposed for the more efficient measure yields an improved finite controller realisation with combined lower bits and higher lower stability bounds. © lEE, 1998.
Istepanian RH, Woodward B, Gorilas E, et al., 1998, Design of mobile telemedicine systems using GSM and IS-54 cellular telephone standards., J Telemed Telecare, Vol: 4 Suppl 1, Pages: 80-82, ISSN: 1357-633X
This paper presents an overview of the design of mobile telemedical systems using cellular telephone channels. A mobile telemedicine communication system was studied using both the GSM and the IS-54 standards, which are the most widely used commercial cellular telephone systems in Europe and North America, respectively. A simulation using a photoplethesmography signal showed successful transmission of data with bit error rates of less than 10(-7) at the receiver for the IS-54 standard and less than 10(-5) for the GSM standard, depending on the mobile channel conditions used.
Istepanian RS, Woodward B, 1997, Microcontroller-based underwater acoustic ECG telemetry system., IEEE Trans Inf Technol Biomed, Vol: 1, Pages: 150-154, ISSN: 1089-7771
This paper presents a microcontroller-based underwater acoustic telemetry system for digital transmission of the electrocardiogram (ECG). The system is designed for the real time, through-water transmission of data representing any parameter, and it was used initially for transmitting in multiplexed format the heart rate, breathing rate and depth of a diver using self-contained underwater breathing apparatus (SCUBA). Here, it is used to monitor cardiovascular reflexes during diving and swimming. The programmable capability of the system provides an effective solution to the problem of transmitting data in the presence of multipath interference. An important feature of the paper is a comparative performance analysis of two encoding methods, Pulse Code Modulation (PCM) and Pulse Position Modulation (PPM).
Istepanian RH, Woodward B, 1997, Use of neural networks in telemedical monitoring of divers., J Telemed Telecare, Vol: 3 Suppl 1, Pages: 70-72, ISSN: 1357-633X
An artificial neural network (ANN) has been developed to predict and classify the risk of medical disorders for certain dive profiles. The telemedical data applied to the ANN represent different physiological and physical parameters that are transmitted acoustically from a diver to a remote receiver. The telemetered data include dive time, maximum depth and decompression stop times and depths. Preliminary tests demonstrated the successful performance of the ANN where classical mathematical and statistical methods had failed due to the complex nature and variability of the parameters involved.
Istepanian RSH, Woodward B, 1996, Spectral analysis of heart rate variability during scuba diving, Pages: 1664-1665, ISSN: 0589-1019
Power spectral analysis of heart rate variability (HRV) is a well known clinical and physiological analysis method. However, the role of the cardiovascular control systems during underwater swimming and SCUBA diving is not completely understood. This paper examines the HRV during SCUBA diving using a recently developed microcontroller based real-time underwater acoustic biotelemetry system. The telemetered results applied to autoregressive modelling for spectral estimation suggest that the methodology can detect changes within the neuroregulatory control systems in response to the different diving regimes. This new system provides wide functional versatility for users interested in real-time underwater heart rate variability and physiological monitoring studies.
Habib Istepanian RS, Habib Istepanian HS, 1996, Suboptimal Bang-Bang control for DC-DC switched mode converters, Pages: 430-435, ISSN: 0537-9989
A new suboptimal Bang-Bang control technique is proposed to improve the performance of switching power converters. Theoretical analysis and computational steps are presented to illustrate the effectiveness yet realization simplicity of the proposed control strategy. The application of the proposed methodology to a boost converter model has shown an improved performance with faster transient response with minimum overshoot in the terminal voltage and minimized current ripple.
Woodward B, Istepanian RSH, 1995, Use of underwater acoustic biotelemetry for monitoring the ECG of a swimming patient
Biotelemetry is a special branch of bio-instrumentation which provides a means of transmitting physiological and biological information from one site to another. There are several cardiological conditions in which it is desirable to monitor critical reflexes and responses from a free-swimming patient, and this paper describes the transmission through water of acoustic signals representing the electrocardiogram (ECG), together with their reception and display. The system has a modular design that can be adapted for the transmission of any parameter, such as heart rate, respiration rate or skin temperature, or any three parameters multiplexed together. The transmission involves the following processes: the amplitude of each ECG pulse is sampled to 8-bit resolution, the least significant bit is discarded to compress the data, then the sample is transmitted by pulse code modulation (PCM). A microcontroller in both the transmitter and receiver allows the ECG data to be sampled, coded, transmitted, received and finally decoded into its original analogue form. The system has been tested successfully in a swimming pool where multipath reverberation was a severe problem.
Istepanian RSH, Goodall RM, Jones SR, 1995, Architectures for high performance digital control processors, ISSN: 0963-3308
A research project focusing on the development of algorithms and architectures for a Control System Processor (CSP) is presented. The design considerations suggest how new processor architectures targeted generally for critical linear time invariant systems can be arranged to yield higher performance controllers than those designed in the classical fashion. This is based on the structuring of the complexity of the digital controllers and an assessment of their associated implementational and computational demands. An active suspension controller is used an example to illustrate some of the issues.
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