By Topic

System Theory, 2002. Proceedings of the Thirty-Fourth Southeastern Symposium on

Date 19-19 March 2002

Filter Results

Displaying Results 1 - 25 of 104
  • Proceedings of the Thirty-Fourth Southeastern Symposium on System Theory (Cat. No.02EX540)

    Publication Year: 2002
    Save to Project icon | Request Permissions | PDF file iconPDF (515 KB)  
    Freely Available from IEEE
  • Author's index

    Publication Year: 2002 , Page(s): 491 - 493
    Save to Project icon | Request Permissions | PDF file iconPDF (151 KB)  
    Freely Available from IEEE
  • Performance of noise canceller using adjusted step size LMS algorithm

    Publication Year: 2002 , Page(s): 248 - 250
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    An adjusted step size LMS (least mean squares) algorithm is proposed for possible improvements in the performance of adaptive FIR filters in nonstationary environments. Nonstationary signals means that the statistical properties of the noise changes in time such as the high frequency channel time variations. In the paper, an adaptive noise canceller is proposed which is based on signal to noise ratio number to adjust the step size. In addition the same algorithm can be used for line enhancement and tracking high frequency channels which is used to provide high data rate in communications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A data compression scheme employing a biologically inspired model

    Publication Year: 2002 , Page(s): 391 - 395
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    The traditional model in biology for the mode of communication between neurons revolves around the integrate-and-fire model. In this model a neuron will fire only if the amount of incoming signal within a certain amount of time meets or exceeds some threshold (i.e., the incoming signal is integrated). Recent work by Izhikevich (2001) has posed another possible model, which he calls the "resonate-and-fire" model. Details of the model are covered in this paper. This model provides the basis for the ideas discussed below. This paper attempts to show how concepts from Izhikevich's research can be used to implement a novel method for data compression. While there are still many challenges to be overcome, it is hoped that a ratio of 4:1 compression may be possible after compression through conventional methods. In addition, an application of these ideas to a simple form of data encryption is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wireless distributed data acquisition system

    Publication Year: 2002 , Page(s): 463 - 466
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB) |  | HTML iconHTML  

    Distributed data acquisition requires a flexible system organization, particularly when individual devices are mobile. The utility companies have been developing similar systems for several years now. In the case of medical devices, a mobile patient monitoring device would allow patients to leave the hospital and engage in normal activity, uploading physiological data only periodically. The wireless distributed data acquisition system presented in this paper is developed for mobile client devices, and mobile gateways. Each client device has some form of secondary storage, such as flash memory, to store the data that it acquired while it is not transmitting the data to the gateway device. The system maintains a database to keep track of the data acquired with respect to the data that it transmits to the gateway device. Each client device is uniquely identified. The gateway device polls client devices within its reach to transfer the client records to database. Gateways use existing communication infrastructure, such as cell phone link, and local connection to upload data to the server. We present the system developed around low-power microcontroller Texas Instruments MSP430F149, using standard 900 MHz wireless link, Smart Media Card as a secondary memory, and a portable PDA based gateway. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic malaria models with environmental changes

    Publication Year: 2002 , Page(s): 396 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    In this paper, we formulate a dynamic model for the transmission of malaria in both host human and vector mosquito populations. We include incubation periods for both infected human hosts and mosquitoes. We further divide the infected human population into subgroups based on their infection history. Threshold conditions which determine whether the disease spreads in the human and vector populations or dies out are obtained. Such conditions are characterized by the reproductive number and an explicit formula for the reproductive number is derived. The reproductive number is composed of key parameters in the disease transmission and those parameters are functionals of environmental variables. Impact of environmental changes on the disease transmission is then discussed through the sensitivity of the reproductive number with respect to the environmental variable. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parallel processing computer architectures for process control

    Publication Year: 2002 , Page(s): 234 - 238
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (607 KB) |  | HTML iconHTML  

    Modern, large-scale, high-speed process control automation is quite complex in nature. Continuous manufacturing processes currently in use require advanced computer technologies such as simultaneous parallel processing architecture for synchronous process operations that take place independent of each other. In order to optimise the performance of a process control system measured through its output variance, suitably structured robust computing structures are necessary for a multi-input/output process control. This paper describes: (1) a multi-ported-memory, star-ring parallel processing computer architecture for the process control of multiple inputs/outputs; and (2) a suitable parallel processing architecture for optimising the performance of an interconnected process control system. Both the architectures use a feedback control algorithm for multi-input/output process control by measuring its performance through its output product quality and for optimising the performance of the inter-connected process control system by using the product quality output as a performance measure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling of epicardial signals in the human body

    Publication Year: 2002 , Page(s): 401 - 405
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB) |  | HTML iconHTML  

    Epicardial signals are time-varying electric potentials on the outer surface of the heart that originate from a signal inside the heart to trigger the heartbeat. Diagnosis of epicardial signals by medical personnel reveals the health of the heart. Modeling of these signals is important in the inverse problem of electrocardiography. In this paper, we present an inverse technique for computing epicardial signals. We present a finite difference method using Laplace's equation for computing the resistance of an arbitrarily shaped conductor. We demonstrate how this method is useful in modeling the currents inside the body due to static electric fields. By applying this method to a model of the human body, we can develop a network of resistors from the heart to various points on the body surface. From actual electrocardiogram (ECG) measurements at the body surface, we can use the derived network to compute source potentials. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Intelligent control of cupola furnaces

    Publication Year: 2002 , Page(s): 435 - 439
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    The objective of this research is to improve the efficiency of the cupola operation in the presence of desired output changes. This is achieved by developing an automatic controller for the cupola furnace. A controller was previously developed that provided tight control over the output parameters of the cupola under little or no desired change. The controller considers physical and practical limitations on the possible inputs. Previous research described optimal pairing of cupola outputs and inputs. This is exploited in a fuzzy controller that pairs oxygen enrichment and blast rate to the outputs of metal temperature and melt rate, respectively. The controller is modified to determine action when problems in production require a slow down or shut down of the melting process. A model is developed using a combination of experimental data and data obtained from the AFS cupola model. The model is a first order multivariable dynamical system. Due to the nonlinearities of the cupola, the model is only accurate for a narrow operating band. By varying the model parameters, simulations show the control to be robust. Simulations in the presence of input disturbances and output sensor noise show the controller efficiently rejects the common noise of a cupola furnace environment. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A survey paper on independent component analysis

    Publication Year: 2002 , Page(s): 239 - 242
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    Independent component analysis (ICA) is a statistical and computational technique for revealing hidden or underlying factors in data. The independent components or sources can be found using ICA provided that all components are independent and non-Gaussian. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Direct fault tolerant RLV attitude control-a singular perturbation approach

    Publication Year: 2002 , Page(s): 86 - 91
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    We present a direct fault tolerant control (DFTC) technique, where by "direct" we mean that no explicit fault identification is used. A technique is presented for the attitude controller (autopilot) for a reusable launch vehicle (RLV), although in principle it can be applied to many other applications. Any partial or complete failure of control actuators and effectors will be inferred from saturation of one or more commanded control signals generated by the controller. The saturation causes a reduction in the effective gain, or bandwidth of the feedback loop, which can be modeled as an increase in singular perturbation in the loop. In order to maintain stability, the bandwidth of the nominal (reduced-order) system is reduced proportionally according to singular perturbation theory. The presented DFTC technique automatically handles momentary saturations and integrator windup caused by excessive disturbances, guidance command or dispersions under normal vehicle conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An accelerometer-based physical rehabilitation system

    Publication Year: 2002 , Page(s): 57 - 60
    Cited by:  Papers (3)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (625 KB) |  | HTML iconHTML  

    This paper presents a portable physical rehabilitation monitoring system based on a personal network of intelligent sensors. Rehabilitation is traditionally carried out in hospitals under supervision of qualified personnel. However, significantly better results could be achieved using out-of-hospital portable monitoring to allow patients computer-assisted rehabilitation in their homes. The new generation of personal digital assistants (PDA), such as Compaq iPAQ, offers large processing power, decent graphical user interface, and compact flash based secondary memory. Therefore, they are perfectly suited for portable monitoring units. Individual sensors are positioned on limbs to analyze movements using 2-axis MEMS accelerometers. The system monitors periods and forces of individual sensors, visualizing relevant physiological data in real-time on PDA, and archiving progress data on compact flash. A specialist supervises current advance and sets new optimum rehabilitation modes, thresholds for forces, step periods, etc. The system generates real-time warnings when predefined thresholds have been exceeded. We are developing a system for hip and knee replacement rehabilitation, as well as general physical rehabilitation. Other possible applications of our system include rehabilitation of stroke and heart attack patients. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Evaluation of the measurement update interval for an adaptive radar scheduler

    Publication Year: 2002 , Page(s): 354 - 357
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (359 KB) |  | HTML iconHTML  

    This paper presents a technique for determining the radar scheduler update interval. Given the system state-variable model and its statistical data, a matrix expression for the general order predictor error covariance matrix is derived. A cost function of this covariance matrix is solved to regulate the radar's Kalman filter measurement update intervals. Simulation experiments are performed and results presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Methodology for the development of an electronic medical record

    Publication Year: 2002 , Page(s): 406 - 411
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    Electronic medical records (EMRs) and computer based patient records (CPRs) hold the opportunity to improve patient care, reduce costs, and facilitate research in medicine. Far too often, however, healthcare organizations and practitioners find that these systems are too costly, lack essential features, or work improperly for their setting. As the result, many decide to develop their own EMR or CPR systems. Often, these undertakings rely on developers and software engineers who are unfamiliar with the concepts, terminology, and the myriad regulations that accompany such development projects. This paper suggests a framework for analyzing, modeling, and developing such a system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Predicting the elasto-plastic response of an arc-weld process using artificial neural networks

    Publication Year: 2002 , Page(s): 440 - 444
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    The quality of a steel arc-welded joint greatly depends on the parameters of the welding process used. Given a particular geometry of the weld, the corresponding welding materials and the restraints used to fix the parts, the feed rate, the speed and the heat input play a significant role in the thermal and elasto-plastic response of the plates. Residual stresses and overall distortions are always of great concern in welding processes and a number of simulation approaches have been developed to assess this behavior. However, these simulations are very computationally intense, making it extremely costly to optimize weld designs. In the paper, a strategically selected set of finite element simulations of a typical welding process are made to train a neural network model, which in turn can be used to effectively predict the weld response at a minimal fraction of the effort required by a standard finite element simulation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stability of false lock states in a class of phase-lock loops

    Publication Year: 2002 , Page(s): 133 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    False lock is a practical, often very perplexing, problem in phase-lock loops (PLLs). When false lock occurs, the PLL may appear to be operating nominally; the phase detector output may have a nominal (usually small) average value, and a conventional lock detector may indicate a correct phase lock state. However, a static average frequency error exists in the loop. While stable false lock states are the most troubling from a practical standpoint, unstable false lock states are possible. This paper describes a method for analyzing the false lock problem in a broad class of PLLs. A functional differential equation and its first variation are developed for the PLL. A qualitative description is given for the functional differential equation solution that corresponds to a false lock state. The stability of the false lock state is related to a characteristic exponent of the first variation equation with respect to the false lock solution. An approximation is developed for this characteristic exponent, and this is used to determine the stability of the false lock state. Finally, the theory is applied to a simple example, and numerical results are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decentralized load frequency control in a deregulated environment using disturbance accommodation control theory

    Publication Year: 2002 , Page(s): 302 - 306
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (394 KB) |  | HTML iconHTML  

    In this paper, a decentralized controller is proposed for the load frequency control problem in a deregulated environment. The deregulation scenario considered here assumes that generating units in each area supply regulated power according to their energy contracts. Disturbance accommodating controllers (DAC) are designed which are decentralized controllers using frequency and tie-line power measurements only. Two examples are given to illustrate the proposed approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Discrete wavelet transform domain adaptive decision feedback equalization

    Publication Year: 2002 , Page(s): 243 - 247
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    In this paper we apply discrete wavelet transform processing to the decision feedback equalization adaptation problem. In particular, the discrete wavelet transform decision feedback equalizer (DFE) performance and complexity are compared to those of the least mean squares (LMS) and recursive least squares (RLS) algorithms. We illustrate, using a simulation example, that the wavelet transform DFE may offer better performance and more robustness against narrow-band interferences as compared to the LMS DFE at a lower complexity than the standard RLS DFE. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Are more models better?: the effect of the model transition matrix on the IMM filter

    Publication Year: 2002 , Page(s): 20 - 25
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB) |  | HTML iconHTML  

    The purpose of this investigation was to determine what approach is best to deal with the question of how to choose the model transition matrix for the interactive multiple model filter. The desire is to determine an approach to choosing the model transition matrix that is "best" in some sense. In the study, many target tracking simulations were run using the interacting multiple models algorithm (IMM) with two models: constant velocity and constant acceleration. During these simulations, the transition matrix used and the target tracks used were varied to allow viewing of behavior of the IMM under different conditions. It is difficult to decide whether changing the probabilities gives better performance, since performance is not measured by one number, but by a balance of competing interests. Using a three-model IMM inputs were used in order to test which values should be on the diagonal and what effect changing the off-diagonal elements would have on the filter's behavior. The results obtained imply that having three models is not necessary except in exceptional cases. This leads one to pose the question: Are more models better?. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Helicopter hover control using linear adaptive control techniques

    Publication Year: 2002 , Page(s): 479 - 483
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    The dynamics of a helicopter are inherently unstable, highly nonlinear and exhibit strong cross-couplings between controls. This paper is concerned with the application of linear adaptive control techniques to stabilize helicopter hover maneuvers. Linear adaptive control techniques enable the de-coupling of multiple-input, multiple-output control problems into simpler single-input, single-Output control problems. This is achieved by using disturbance accommodation control observers to estimate in real-time the effects of all the terms with the exception of nominal effects of the control terms. This approach is inherently robust because the only knowledge of the plant it requires is the approximate representation of the effects of the control. The specific challenge in this application is that, unlike aircraft applications where actuator responses can be accurately modeled, in helicopter the rotors play the role of actuators, and their responses are subject to considerable uncertainty. Numerical results presented here demonstrate that the proposed approach achieves improved tracking of commanded maneuvers, compared to traditional multi-loop designs. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A non-contact ammeter using phosphor thermometry

    Publication Year: 2002 , Page(s): 184 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    An experiment was conducted to study the feasibility of a remote (noncontact) ammeter based on phosphor thermometry. Elevated surface temperature (due to current) of a small transformer was measured by employing phosphor thermometry. A nearly linear relationship between surface temperature and current indicates potential use for this technique. Some modifications to the technique with the aim of reducing relatively long thermal stabilization time, observed in this experiment, are suggested. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ambiguity diagram performance for clutter-limited detectors

    Publication Year: 2002 , Page(s): 36 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (407 KB) |  | HTML iconHTML  

    This paper address the ambiguity diagram performance of a discrete time clutter-limited detector. These detectors are different from matched filters and have very low range-time sidelobes. The ambiguity function is presented for two versions of the clutter-limited detectors and the ambiguity diagrams are plotted and compared to the standard matched filter ambiguity diagram. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A dynamic power profiling of embedded computer systems

    Publication Year: 2002 , Page(s): 15 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    Power consumption is one of the most critical system design parameters, particularly in the case of battery powered computer systems. This paper presents a novel method of data acquisition and processing suited for the dynamic power estimation of computer systems. It is the goal of the designer of these systems to maximize the useful system operation time with a fixed battery charge. In order to achieve the goal of maximum lifetime, several key data points about the real-time power consumption of the system are needed. These include average, maximum, and minimum current drawn over a period of time and also instantaneous current drawn by the system while it is active. We developed a separate power measurement device to provide the real-time data sets generated by the system under test. The power measurement device will determine the current drawn by the system under test, and will provide to the user the average, maximum, and minimum current drawn by the system during the period of the test. The power measurement device can also provide real-time current draw of the system under the test, within the precision of the power measurement device. We use a very low power microcontroller, Texas Instruments MSP430F149, for data acquisition and processing. We also provide a real-time data stream of average samples to the standard RS-232 serial communications port with the sampling frequency of approximately 6.9 kHz. Real-time traces of the dynamic power consumption collected by this power measurement device allow designers to modify hardware and software architecture to extend the system lifetime with a given battery charge. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Virtual attendance in real engineering labs

    Publication Year: 2002 , Page(s): 61 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    Engineering laboratory equipment at UTC has been made available for users via the World Wide Web. Users can conduct systems lab experiments from remote sites, anytime day-or-night, any day of the week. This paper describes the development of these systems, the current situation and future plans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of CORDIC algorithm implementations on FPGA families

    Publication Year: 2002 , Page(s): 192 - 196
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    This paper presents different implementations of CORDIC algorithm on two field programmable gate array (FPGA) families, namely Xilinx XC4000XLA and VIRTEX series. Pipelining is used to improve the throughput and speed of the design. Xilinx foundation computer aided design (CAD) tools are used for synthesis, simulation and implementation on the FPGAs. A comparative study on the performance of these implementations is presented. Metrics for comparison and analysis are speed and cost. The area occupied by the design in the FPGA gives a measure of the cost. Based upon the metrics, the best design is identified. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.