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Date 5-7 April 2002

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Displaying Results 1 - 25 of 95
  • Proceedings IEEE SoutheastCon 2002 (Cat. No.02CH37283)

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    Freely Available from IEEE
  • Author index

    Page(s): 481 - 482
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    Freely Available from IEEE
  • MPLS performance modeling using traffic engineering to improve QoS routing on IP networks

    Page(s): 152 - 157
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    The Internet architecture has evolved over time, incorporating new technologies and adapting to the changing needs of its users. The introduction of multi-protocol label switching (MPLS) as a part of the Internet forwarding architecture has immediate applications in traffic engineering (TE) and quality of service routing (QoSR). MPLS supports throughput and delay sensitive real-time media services such as Internet-based distance learning or I-DL. This paper presents a performance service model, which incorporates TE and QoSR of the MPLS to support I-DL while retaining the efficiencies of the backbone structure of the Internet. This new service model is simulated using OPNET and its performance is compared to existing IP routing algorithms View full abstract»

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  • A review of dielectric properties of normal and malignant breast tissue

    Page(s): 457 - 462
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    This paper presents a review of the dielectric properties of normal and malignant breast tissues for radio through microwave frequencies, as well as a brief summary of the experiment methods and the mechanisms that explain the difference in the dielectric properties of normal and malignant breast tissue. This information provides a basis for the development of diagnostic techniques for breast cancer and also highlights the areas that are in need of more experiments View full abstract»

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  • Development of a memory-dynamic NU-FDTD Maxwell's solver for wireless communications applications

    Page(s): 201 - 204
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    In this research, a generalized nonuniform finite difference time-domain (NU-FDTD) Maxwell's solver has been developed using a memory-saving technique, the MFC class templates. The dynamic sizing property of the MFC array classes is integrated to the solver such that there is more memory flexibility in handling complicated structures. The algorithm is validated with a number of representative guided-wave structures and antennas with satisfactory improvement in computational efficiency View full abstract»

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  • Multiple path planning for a group of mobile robots in a 3D environment using genetic algorithms

    Page(s): 359 - 363
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    We present the development, simulation and testing of a new approach using genetic algorithms for planning optimum paths for a group of mobile robots to be moved from arbitrary starting positions to final a number of targets in a known multi-obstacle 3D environment. The factors considered for fording optimum paths for the group of mobile robots are the size and location of obstacles in the environment and the topographical elevations of the environment. First, a digital picture of the environment is transformed into a grid map by a graphic simulator. The obstacles are mapped according to their location, shape and size. The ground elevations are represented using a color-coding scheme. The resulting grid map of the environment contains information about initial positions of the robots, target positions, obstacle locations and ground elevation. Hence, the location and size of obstacles and altitudes of the elevation of the environment are presented in the map. The genetic algorithm modules takes information about the environment from the grid map and search for optimum paths to move a group of mobile robots to the specified targets View full abstract»

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  • A resource synchronization protocol for dynamic scheduling real-time CORBA

    Page(s): 15 - 20
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    In 1989, the Object Management Group (OMG) formed a Real-Time Special Interest Group (RT SIG) with the goal of extending the Common Object Request Broker Architecture (CORBA) standard with real-time specifications. The most recent effort attempts to meet the requirements of dynamic distributed real-time systems. In such systems, one of the requirements is resource access synchronization for tasks with end-to-end timing constraints under dynamic scheduling. The paper proposes a resource synchronization protocol that meets the requirements of the dynamic distributed realtime system specified by the Dynamic Scheduling Real-Time CORBA (DSRT CORBA). The proposed protocol can be applied to both Earliest Deadline First (EDF) and Least Laxity First (LLF) dynamic scheduling algorithms, allows distributed nested critical sections, and avoids unnecessary runtime overhead View full abstract»

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  • Improving the genetic algorithm performance in aerial spray deposition management

    Page(s): 306 - 311
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    Determining the parameter value settings to use as input to AGDISP (aerial spray simulation model) in order to produce a desired spray material deposition is considered an instance of the parametric design problem. SAGA (spray advisor using genetic algorithm) was developed to solve this problem. In this paper, we describe several approaches to improve the performance of SAGA. First, we replace the original generational genetic algorithm with a steady-state genetic algorithm, and the original roulette wheel selection with tournament selection. We call the new system SAGA2. Second, we apply a neural network to improve the initial population, crossover, and mutation. We call this version SAGA2NN. Then, we apply GADO, a general-purpose approach to solving the parametric design problem. The integrated GADO version is called SAGADO. Finally, we compare the performance of SAGA, SAGA2, SAGA2NN and SAGADO View full abstract»

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  • Design of an electromechanical pump system for training in beating heart cardiac surgery

    Page(s): 192 - 196
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    Heart surgeons and trainees benefit greatly from continuous practice of bypass surgery and other cardiac operations. This is true of beating heart surgery where, unlike traditional methods, the heart is not arrested during the operation. At the Dept. of Surgery, University Hospital of the West Indies (UHWI) a system has been devised to simulate a beating human heart using intra-ventricular balloons, which are inserted inside a preserved in vitro porcine heart and made to pulsate using a pneumatic pump. The work is currently being developed in collaboration with the School of Engineering at the University of Technology, Jamaica (UTech) and the Dept. of Mathematics & Computer Science at the University of the West Indies (UWI), with the aim of producing a computer controlled device capable of simulating the range of intra-operative cardiac behaviours typically found in heart surgery. An electromechanical pumping system is described, based on a computer controllable linear actuator. A comparison of associated pulsatile pump choices is presented along with results of the design of a prototype diaphragm pump, which was tested with the porcine heart, demonstrating normal and abnormal beating, and ventricular fibrillation. A software architecture is also presented, showing how the heart may be controlled in a variety of beating modes over the course of a surgical training session View full abstract»

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  • 2-D auditory mapping of virtual environment using real-time head related transfer functions

    Page(s): 364 - 369
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    The human brain is capable of localizing sounds from events occurring in its surroundings. It is able to identify and pinpoint from which directions the sounds come. This project takes advantage of that ability to create a simple auditory map of a virtual environment with the use of head related transfer functions (HRTF). HRTF are the basis of the most prominent techniques for digital sound spatialization. In this project a synthetic virtual environment is defined by a maze of vertical and horizontal walls drawn on the computer screen using Matlab's graphic user interface (GUI) components. In this virtual environment the subject is represented by the computer cursor. The distances from the cursor to the nearest virtual walls are calculated continuously and used to control the intensity of four virtual sounds that are simulated as if originating at the front, back, left and right of the subject. These four spatialized sounds are delivered through headphones to a blindfolded user as he/she navigates the virtual environment stepping the cursor with the four arrow keys on the keypad of the computer. Virtual navigation tests with 14 subjects confirm that the remote navigation cues provided by the spatialized sounds are more helpful in avoiding collisions with the virtual walls than a simple warning tone provided to the blindfolded user in the immediate vicinity of the walls View full abstract»

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  • Modeling of traffic sources in ATM networks

    Page(s): 82 - 87
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    ATM networks integrate different communication services such as data, voice and video, which have different traffic characteristics. To evaluate the performance of ATM networks, accurate traffic models that can capture the statistical characteristics of actual traffic are required. The traffic models are employed either as part of an analytical model, or to drive a discrete event simulation. This paper reviews the modeling techniques of traffic sources in ATM networks. The traffic models can be classified into short-range and long-range dependent models. Short-range dependent models such as renewal models, Markov and Markov modulated processes, and regression models were introduced in this paper View full abstract»

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  • Integratable robot simulation tools

    Page(s): 370 - 374
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    A new graphical simulation package, which is capable of interoperability with other extensive programs, is proposed. A built-in LISP interpreter based on COMMON LISP allows a user to model and manipulate the robot while the result is displayed on a 3D graphical display. Other programming languages that are compatible with the component object model interface can also be applied to the modeling and simulation. The simulation package provides many useful features such as collision detection, inverse kinematics, matrix transformation operations, and several graphical user interfaces. The simulation objects are built based on a triangle strip model to form primitive objects such as a box, cone, sphere, etc. These primitive objects are combined to construct the robot that may contain several serial or parallel links so that many possible types of robots can be modeled View full abstract»

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  • Advancing technology in wireless communications

    Page(s): 468 - 470
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    This paper presents information on the recent advances of practical wireless networks for voice, data, image and video services in areas as small as an office and as large as the entire planet. This paper also addresses the potential economic and sociological impacts of mobile communications. We also discuss the next generation of cellular telephones, computer networks and pagers being developed to meet the demands of increased quality and capacity of a growing telecommunication market View full abstract»

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  • The practical use of model checking in software development

    Page(s): 21 - 27
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    The paper presents the result of work that explored the use of model checking, investigated modeling tools, and developed a process for model checking software systems. A prototype tool for visual modeling was developed and helped the research team understand the role of tools, such as SMV, and clarified the steps involved in the model checking process. The paper summarizes the engineering observations made by team members during their model checking work. These observations were refined through the use of simple challenge problems and organized into a process that highlights some of the practical issues associated with model checking software systems View full abstract»

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  • Time-bounded algorithm for two-player games

    Page(s): 312 - 316
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    We present a time-bounded algorithm for two-player games, which generates partial game trees in accordance with the theme that when comparing the values of several alternative moves, the criterion should depend not only on their apparent scores but also on the amount of time already expended in their examination. We show that such an algorithm admits an interpretation as a generalized minmax search View full abstract»

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  • Test results for the development of a novel region-based DOCSIS compliant cable plant system and protocol to optimally reduce contention mini-slot collisions and to support QoS on DOCSIS 1.1/1.2 networks

    Page(s): 166 - 170
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    Current Data-Over-Cable Service Interface Specification (DOCSIS) standards require meeting QoS objectives to enhance the multiple and fast service environment. We present results and a technique that achieves record reduction in contention mini-slot (CMS) collisions by means of dividing the stations in the network efficiently. A primary goal of the design is to keep the entire protocol at the head-end (HE). The goal also includes leaving everything else in the current hybrid fiber/coax (HFC) systems unchanged. Our technique shows that with small changes in the medium access control (MAC) protocol at the HE, we can efficiently and dynamically divide the stations in the upstream based on load conditions to allot a specific amount of CMS for each region. The mechanism also proposes for the collection of channel statistics and channel monitoring to statistically configure the necessary division for optimum performance. We have also developed a simulation and visualization tool using MATLAB and a suitable and effective traffic generator model that could be extracted from network parameters. The results prove that the proposed approach amounts for a record 40%-45% reduction in mini-slot (ms) collisions View full abstract»

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  • Synergetic control of a boost converter: theory and experimental verification

    Page(s): 197 - 200
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    The proposal of new control techniques in the field of power electronics, especially for switching converters, for various applications is an interesting development. In this paper, a new approach for the synthesis of converter controllers, based on synergetic control theory is discussed. This method is completely analytical in its effort to synthesize the converter aggregated controllers based on fully nonlinear models of the converter. Such types of controllers provide asymptotic stability (steady-state) with respect to the required converter operating modes. Also, they are unaffected by load variations and show robustness to variation of converter parameters. In comparison with the available types of PI converters, synergetic controllers are far superior with regard to their dynamic characteristics. The theory of the approach is presented along with a detailed discussion of a synthesis example for a boost converter, the simulation and experimental results. The experimental results have been obtained from a laboratory prototype built for this purpose View full abstract»

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  • Computation of transient magneto-mechanical problems in electrical machines

    Page(s): 187 - 191
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    This paper investigates numerical results relating to several aspects on noise and vibrations of electrical machinery. This is based upon the coupling between the magnetic field and the mechanical deformation in the stator. The coupling is typically considered by using reluctance forces. Since the deformations occurring are small compared to the machine's dimensions, there is no feedback to the magnetic system in numerical models. However, stator deformations are caused not only by reluctance forces, but also by magnetostriction effect of the stator iron. Magnetostriction is one of the main causes of noise in electromagnetic systems particularly when the flux density is above 1.5 T. In this paper, we show computational results of a transient numerical model developed earlier. This model incorporates the magnetostriction effect in addition to other electromechanical forces and related material interactions. Implementation results presented here for a 2-hp, surface mounted, permanent magnet motor. The results indicate that magnetostrictive forces are significant and must be accounted for in the electromagnetic system's design stage View full abstract»

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  • IP header compression in the SGSN

    Page(s): 158 - 161
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    This paper discusses how protocol header compression schemes can be implemented in the Serving GPRS Support Node (SGSN) as part of the GSM recommendations. We briefly describe details of the two compression algorithms currently selected for implementation by the recommendations committee, followed by an explanation of how these schemes can be implemented in the SGSN View full abstract»

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  • Using a pseudo-random binary sequence as a mother wavelet in the wavelet-correlation system identification method

    Page(s): 58 - 61
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    The wavelet-correlation (W-C) method is a method of system identification that has been derived as a generalization of the correlation method which uses wavelets rather than correlation functions to determine the system transfer function estimate. The input signal for this identification method is the mother wavelet which must also meet the system identification requirement of persistent excitation. A pseudo-random binary sequence is selected as the mother wavelet and is shown to be a better input signal than wavelets View full abstract»

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  • Advantages of slowed electromagnetic waves

    Page(s): 375 - 380
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    The features of slowed electromagnetic waves and their advantages are considered. Examples of new methods and devices combining the advantages of relatively high and relatively low frequency bands are shown. Concentration of an electromagnetic field caused by wave deceleration leads to a significant increase in parameters of processes and devices based on slowed wave application. It is shown that coupled slow-wave structures application allows electric and magnetic fields to split in transverse direction which leads to an additional improving in parameters and characteristics (the sensitivity and interaction efficiency increase, new processes developing, etc.). The possibilities of slowed wave application for micro-miniaturization of RF and microwave passive elements, for measurements, electromagnetic heating, and for physiotherapy are considered View full abstract»

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  • Design and development of a user interface to remotely control a radio telescope using virtual instruments

    Page(s): 279 - 282
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    Radio telescopes are the main instruments used in radio astronomy. In order to encourage students of Grades K-12 to be interested in astronomy, a group of students from South Carolina State University have undertaken to computerize a 4.6 meter telescope, called Smiley. The team of students proposed to use a graphical programming language, called Laboratory Virtual Instruments Engineering Workbench (abbreviated LabVIEW) for instrumentation, data acquisition and analysis View full abstract»

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  • The importation of an ACSL-based model into VTB

    Page(s): 471 - 474
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    The VTB (Virtual Test Bed) project is dedicated to developing a new environment for simulation and virtual prototyping of power electronic systems. This paper describes an experience of the importing of an ACSL (Advanced Continuous Simulation Language) model: the all-electrical icebreaker Healy of the US Coast Guard. The goal of the project is to support the multi-language capabilities of the VTB and to improve the ship's model. This legacy model has been tested and validated data has been made available for comparison View full abstract»

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  • Development of software for mobile robot control over a radio frequency communications link

    Page(s): 414 - 417
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    In the spring of 2001, work began on a mobile robot for an advanced computer engineering class. One of the key parts to the success of this robot would be the ability to control it from a computer terminal. In order to make this feasible, the computer would communicate to the robot through a wireless connection. The robot's on-board computer would perform any computations needed, so the robot would not need to send any information on the controlling computer. The communication link was designated to be one way, from the computer to the robot. For reasons including cost efficiency, ease of use, and range, RF communication was chosen. Using two development boards from Linx Technologies, we had the capability of communicating through the computer's serial port. The boards boasted a line of sight range of about 1000 feet. The board acts as nothing more then a transmitter and receiver, so any error correction must be dealt with in the software. Often errors come from interference created by surrounding RF devices, and appear as incorrect bits in the data stream. In order to handle such errors, methods involving redundancy were used. When the stream of information is sent, it is initialized by a start byte. This is followed by the commands, each of which is repeated three times followed by a stop byte. On the receiving end, the software waits for the start byte and then stores each byte that follows. They are then compared with one another and determined to be either clean data or an error. If the data is clean, the robot then executes the commands. By monitoring the data received by the receiver we were able to see the need for such software. Upon powering up the board, miscellaneous bits are received, and if there is no error correction, the robot could misinterpret these for a command. The boards also received stray bytes while idle, so the software would also eliminate this. Software development was started and initially tested over a crossover cable connecting the two serial ports. This allowed us to ensure that the software was working with out seeing any errors at first. Finally the software was used with the RF boards and seen to be functional. This paper explores, in depth, the methods used by software to correct errors that may develop in RF communication. The materials used are discussed in greater detail along with the creation of the software. Experimental results show the methods to be precise, and fit the design application needs View full abstract»

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  • The Paraguin compiler - message-passing code generation using SUIF [Stanford University Intermediate Format]

    Page(s): 1 - 6
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    Introduces the Paraguin project at the University of North Carolina at Wilmington. The goal of the project is to build an open-source message-passing parallelizing compiler for distributed-memory computer systems. We discuss the progress we have made in developing this compiler as well as mention the parts that have not yet been developed. It is our intent that, by providing an open-source compiler, we will stimulate research in automatic message-passing parallelism and encourage collaboration. We demonstrate a technique to improve the performance of a message-passing program by overlapping communication with computation. Although the original concept was introduced previously by S.P. Amarasinghe and M.S. Lam (1993), the algorithm was not developed nor shown to provide any benefit. Our preliminary results indicate that the technique significantly improves the performance. We were able to reduce the running time of our test program by 4-65% View full abstract»

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