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System Theory (SSST), 2013 45th Southeastern Symposium on

Date 11-11 March 2013

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Displaying Results 1 - 25 of 30
  • [Front cover]

    Page(s): 1
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    Freely Available from IEEE
  • [Copyright notice]

    Page(s): 1
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    Freely Available from IEEE
  • Hardware friendly schemes to implement exponential linear phase FIR filters

    Page(s): 55 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    A family of exponential linear phase FIR filters was previously proposed. This work investigates various hardware schemes that can be used to implement fast exponential linear phase FIR Filters. The investigated schemes are the alternative base implementation for filters with integer bases and a recursive implementation for filters with fixed-point bases. Both schemes are described in hardware description language, synthesized, and simulated. The results show that both implementations can achieve high operating frequencies with a reasonable hardware size. View full abstract»

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  • System interconnections and combinatorial integer sequences

    Page(s): 135 - 140
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    Given two nonlinear input-output systems which are analytic in the sense that they have convergent Fliess operator representations, it is known that their interconnection in almost any fashion will produce another system in this same class. Recent work has focused on characterizing the radius of convergence for a variety of such interconnections. A key observation in this analysis was that certain combinatorial integer sequences naturally appear. The first goal of this paper is to gather from the literature all the known relationships between system interconnections and such sequences and organize them in a coherent manner. In the process it becomes clear that Stirling numbers play a central role in the most nontrivial types of system interconnections, namely, cascade and feedback connections. The second goal is to describe these relationships. View full abstract»

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  • A real-time initial-condition injection technique for implementation of discrete/continuous control-algorithms

    Page(s): 114 - 118
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    A generic signal-processing technique is described that enables computer-simulation studies, and practical hardware-implementation, of “real-time-determined” changes/updates in the “real-time initial-conditions” that must be “injected” into various real-time integration-operations comprising a Discrete/Continuous (D/C) Control-Algorithm. An illustrative example is presented. The “initial-condition injection” technique introduced here is also applicable-to a broad-variety of computational or simulation applications involving the real-time imposition of a sequence of strategic "jump"-changes/updates of the evolving real-time values of various state-variables xi (t) associated with a dynamical system or process. For instance, such as those encountered-in the simulation of Newtonian dynamics associated-with “abrupt” changes in mass and/or “momentum” that are natural consequences of various kinds of elastic and non-elastic impacts, collisions, and mass-separations/mergings. View full abstract»

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  • High accuracy three-dimensional radar sensor design based on fuzzy logic control approach

    Page(s): 22 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    A radar sensor is used to determine the speed of a moving object. This function is made possible by the Doppler effect. However, relying on single radar sensor can have some shortcomings; for instance, (1) A single radar sensor can only accurately measure the speed of a target that is moving either directly towards or away from the sensor, and (2) Only one reading from each trigger can be obtained. In this paper, a novel three-dimensional radar system is proposed to address these disadvantages in target tracking. Furthermore, a fuzzy logic controller is proposed to minimize the error between the measured and actual speed. Experimental results show that such a system can improve tracking of the object with 10X better in error reduction in terms of accuracy and signal noise. View full abstract»

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  • A new passcode based approach for hiding classified information in images

    Page(s): 141 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (606 KB) |  | HTML iconHTML  

    This paper proposes a method of hiding classified data in images based on three different levels of security. Instead of hiding data directly, pixels are selected randomly and their higher nibble bits are matched with the data bits. A two bit code (2BC) is generated to encode the location of the matching bits. The two bit code is embedded in the image based on a password using three different suggested techniques. Simulation results on IEEE standard images of size 512 by 512 show that the suggested techniques are capable of achieving PSNRs between 56 dB and 67 dB with hiding up to 800 ASCII characters. The three different levels of security make this method highly difficult to intercept and useful for secure open channel communications. View full abstract»

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  • Combined direct-indirect adaptive speed control strategy for wind induction generator

    Page(s): 75 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    A combined direct and indirect model reference adaptive controller for variable speed wind induction generator is presented. The main concept of the proposed philosophy is to ensure automatic change of the controller parameters so that they correspond to the current generator's environment and provide an appropriate control action to improve the overall control system performance. The effectiveness of the proposed technique is demonstrated through computer simulation. The obtained results confirm the capability of such control scheme. View full abstract»

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  • Modeling and control of a micro-grid set up using photovoltaic arrays

    Page(s): 80 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    This paper presents a complete mathematical model of a micro-grid set up with PV arrays. The model consists of mathematical design and development of PV module and arrays, power conditioning DC/DC converter and the inverter set up. These designs are integrated with an inverter controller that controls the voltage at a power system bus. The complete system is used as a micro-grid set up connected to a power grid. Testing and evaluations of the micro-grid is then conducted using off-grid and on-grid studies. The uniqueness of the proposed modeling and control includes a complete model's details of micro-grid set up with PV system, power conditioning devices and load model, the utilization of an MPPT and feedback controller to control the output voltage and current. Thus it provides an appropriate real-life testing platform for micro-grid connections to power grid. Simulation results show the effectiveness and the accuracy of this micro-grid model to emulate real-life scenarios. View full abstract»

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  • Approximation of P-V characteristic curves for use in maximum power point tracking algorithms

    Page(s): 88 - 93
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    A curve fitting method that approximates the P-V characteristic curve of a given solar array with a fourth order polynomial is presented. The coefficients of the approximated P-V characteristic curve are strongly dependent on cell temperature. The strong dependence of the P-V curve on cell temperature allows the P-V characteristic curve of a given system to be written as a function of both panel voltage and cell temperature. The curve fitting method presented can be used in an indirect maximum power point tracking algorithm for use with solar powered systems. Experimental results are presented to confirm the validity of the method. View full abstract»

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  • Stream cipher design using cellular automata implemented on FPGAs

    Page(s): 146 - 149
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1020 KB) |  | HTML iconHTML  

    Pseudo-random number generators (PRNGs) are a key component of stream ciphers used for encryption purposes. While linear feedback shift registers (LFSRs) combined with nonlinear feedback shift registers (NFSRs) have typically been utilized for PRNGs, the use of cellular automata (CA) is another viable option. This paper explores the combination of LFSRs and CA as the key components of an efficient stream cipher design for implementation on Field Programmable Gate Arrays (FPGAs). The proposed stream cipher design builds upon a recent published design known as A2U2. The suite of statistical tests found in the Diehard program is utilized to evaluate the quality of random numbers from the proposed CA-based stream cipher. Comparisons with the A2U2 design indicate that the use of CA have the potential to improve the quality of the random numbers generated and hence increase the security of the cipher. View full abstract»

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  • Handoff management with a delay requirement in femtocell networks

    Page(s): 119 - 123
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (399 KB) |  | HTML iconHTML  

    Radio communication has come a long way from the initially deployed 1G voice (Amps) to modern 3G and 4G networks. A technology that holds promise to provide the next leap in peformance is femtocell. Femtocell technology brings the network closer to the user by adding smaller cells, which provide the benefit of higher quality links and more spatial reuse. To fully exploit this diversity realized at the physical layer some challenging issues have to be addressed. Making a handoff decision is one such issue where the user has various power levels available from Macro Base Station (MBS) and Femto Base Station (FBS). From a Base Station's (BS) perspective, there may be many users with close SINR values needing service but all users cannot be accommodated due to bandwidth limitation. To make these decisions, appropriate handoff mechanisms need to be adapted to fully exploit the advantages of these networks in various scenarios. In this paper, we extensively study methods to optimize handoff decisions under the open access scheme of operation, maintaining Quality of Service (QoS) thresholds to maximize overall network capacity such that fairness among users is maintained as well. We aim at developing a low-complexity algorithm with a small dwell time before handing off a macrocell user to a nearby femtocell and vice-versa. When the number of users in the network is smaller in comparison to the available FBSs, we observe better performance in reducing unnecessary handoffs. View full abstract»

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  • Stochastic time scales: Quadratic Lyapunov functions and probabilistic regions of stability

    Page(s): 98 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1482 KB) |  | HTML iconHTML  

    We present a version of Lyapunov theory for stochastically generated time scales. In the case of quadratic Lyapunov functions for the LTI case, our results improve the requirement that spec(A) ⊂ Hmin. Our approach also allows us to consider a special class of LTV problems where the dependence on time is only through the graininess. View full abstract»

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  • Observer based feedback controllers on stochastic time scales

    Page(s): 104 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    We study the problem of stabilization via state feedback where the time between sampling points is not known a priori, but has known statistical properties. In particular, we assume that the distance between sampling points is an independent sequence of random variables with known mean and variance. We consider the cases where the state is known outright and where the state is estimated via an observer. View full abstract»

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  • Simulation of a switched series-resonant receiver for wireless power transfer applications

    Page(s): 94 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    There has recently been considerable renewed interest in commercial development of wireless power transfer (WPT) through magnetically-coupled resonant circuits. One of the problems inherent in WPT is the large variation in power delivered to the load if the flux-coupling coefficient from primary to secondary resonators is allowed to vary. Power delivery may be regulated by either supply-side or load-side regulation, but load-side regulation is less complex as it does not require feedback from the load to the source. The paper analyzes through state equations a proposed method of load-side regulation and develops and validates a linearized model. View full abstract»

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  • Failure mechanisms in MOSFET square-wave drivers for wireless power transfer applications

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB) |  | HTML iconHTML  

    Reports from experimental laboratory work have described catastrophic failure of power MOSFETs used in square-wave voltage sources driving resonant four-coil wireless power-transfer (WPT) networks. Simulation with PSpice has duplicated the problem, identified its probable origins, and presents possible avenues for amelioration. View full abstract»

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  • Mixed-signal System-on-a-Chip (SoC) verification based on SystemVerilog model

    Page(s): 17 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB) |  | HTML iconHTML  

    Simulation speed and a lack of test approaches are the main difficulties in the mixed-signal verification of a complex System-on-a-Chip (SoC). In this paper, an equivalent high-level Radio Frequency (RF) model is created by the SystemVerilog language and integrated into a mixed-signal SoC. Such a model can be executed on a digital simulator, which is dramatically faster than the traditional method using an analog solver. Some mixed-signal verification approaches based on digital methods (including constrained random data generation, assertion-based verification, coverage-driven verification, and Verification Methodology Manual) are also presented as well as a case on the integrated SoC. View full abstract»

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  • Managing performance and efficiency of a processor

    Page(s): 59 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB) |  | HTML iconHTML  

    The performance of a processor generally means how fast it can execute a task. For a given architecture we can measure the size of a task as the number of clock cycles it will take to execute. Then clock frequency (f) will determine the execution time. Normally, the frequency can be raised if the supply voltage Vdd is increased. This, however, increases the power and energy used. We introduce a new measure, cycle efficiency (η) as cycles per joule that gives the rate of computational work per unit energy. Similar to f, η is also a function of Vdd. We provide a method of characterizing a processor in terms of its f and η versus Vdd characteristics. Intel Pentium M processor with an assumed 90nm CMOS PTM (predictive technology model) is used as an example. For a demonstration of performance and energy management, we consider a program that executes in 1.8 billion clock cycles. At the nominal operating supply of 1.2V we have f = 1.8GHz and η = 15 megacycles/joule. The program executes in 1 second and uses 120 joules. For operation at 0.6V, f = 277MHz and η = 70 megacycles/joule, resulting in a run time of 6.5 seconds and consumption of 25 joules. We also find a subthreshold voltage extreme of 200mV, f = 54.5MHz and η = 660 megacycles/joule. Now the program will take 33 seconds but will consume only 2.27 joules. Thus, using cycle efficiency and clock frequency one can manage the time and energy performances according to the requirements of a computing task. View full abstract»

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  • Improving the speed of convergence of GMRES for certain perturbed tridiagonal systems

    Page(s): 63 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (125 KB) |  | HTML iconHTML  

    Numerical approximations of partial differential equations often require the employment of spatial adaptation or the utilization of non-uniform grids to resolve fine details of the solution. While the governing continuous linear operator may be symmetric, the discretized version may lose this essential property as a result of adaptation or utilization of non-uniform grids. Commonly, the matrices can be viewed as a perturbation to a known matrix or to a previous iterate's matrix. In either case, a linear solver is deployed to solve the resulting linear system. Iterative methods provide a plausible and affordable way of completing this task and Krylov subspace methods, such as GMRES, are quite popular. Upon updating the matrices as a result of adaptation or multi-grid methodologies, approximate eigenvector information is known stemming from the prior GMRES iterative method. Hence, this information can be utilized to improve the convergence rate of the subsequent iterative method. A one dimensional Poisson problem is examined to illustrate this methodology while showing notable and quantifiable improvements over standard methods, such as GMRES-DR. View full abstract»

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  • Relay positioning for energy saving in cooperative networks

    Page(s): 124 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    The number of Access Points (AP) in a network is much smaller than the network users. Hence, some users may be far from Aps requiring more power to transmit data. Cooperative communication has been proposed, which uses the broadcast nature of the wireless medium to exploit the spatial diversity in wireless networks. Users in cooperative communication system work cooperatively by relaying the packets through a relay node(RN). One issue is to find an near optimal positions for the limited number of available relays to reduce energy consumption of the users. In this paper, we investigate the position of the relays and its effect on energy saving in cooperative wireless networks. Initially, we use a greedy algorithm to determine the position of the relays and determine the energy saving achieved from this algorithm. Then, we use our improved iterative algorithm to place the relays. Using simulations, we compare both the algorithms in terms of average energy consumption, average number of hops and average r-cover (RNs form an r-cover if each user is within distance at most r from the RN). It is evident from the simulation results that the improved algorithm outperforms the greedy algorithm in all the above mentioned aspects. The results provide us an insight into positioning of the relays in a cooperative wireless network to reduce energy consumption of the users. View full abstract»

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  • Intelligent hybrid vehicle management systems

    Page(s): 27 - 34
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (474 KB) |  | HTML iconHTML  

    This paper addresses system design and integration challenges involved in meeting the requirements for coordinated deployment of Intelligent Hybrid Vehicle Systems. A hybrid vehicle can run purely on a gas engine, purely on an electric motor, or a combination of both. Advanced hybrid vehicles are designed to use a vehicle management system that integrates many subsystem functions into one system. However, many recent hybrid vehicles do not focus on the utilization of decision support techniques for the implementation of system design. The decision support design emphasizes a driver-oriented and automatic-oriented drive-by-wire vehicle system. The top-down functional decomposition and bottom-up physical integration design methodologies help to create an augmented functional analysis in the device level software. The significant portions are devoted to introducing the design stages and establishing the hybrid vehicle management system. View full abstract»

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  • Semi empirical cadmium sulfide transistor model combining grain defects and semiconductor thickness variation

    Page(s): 6 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    Proposed and tested is a methodology for modeling polycrystalline thin film transistors which exhibit shifts in threshold voltage due to both grain boundaries and semiconductor thickness. The process involves a model, which uses in part standard-analytic terms. It also includes terms for grain defects and for thickness added in using numerical simulation testing. From this testing, the threshold voltage for the CdS transistor exhibited an optimum thickness for enhancement mode operation. The semi empirical model was then brought into alignment with experimental results for a CdS transistor by adjusting the interface charge. Predictions from the semi empirical model produced transistor output characteristic and transfer curves showed to be in good agreement with experimental data. View full abstract»

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  • A fuzzy self-constructing algorithm for feature reduction

    Page(s): 35 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    The main aim of text categorization is the classification of documents into a fixed number of predefined categories. In text categorization, the dimensionality of the feature vector is usually high. Various approaches have been proposed to reduce the dimensionality of the feature vector while performing automatic text categorization. This paper deals a fast fuzzy self-constructing algorithm that reduces the dimensionality of a feature vector. We also perform automatic categorization of text and hypertext documents using a Support Vector Machines (SVMs) classifier. AS an illustrative example, we considered a set of documents with 15 documents with up to 30 feature words. A fuzzy self-constructing algorithm was used to obtain the reduced number of features. During the training phase the SVM classifier was trained using the reduced set of features. During the decision making phase the SVM classifier was used to classify unknown documents. View full abstract»

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  • Memristor Drift Model based on conservation of mobile vacancies

    Page(s): 12 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    A significant percentage of the analysis applied to memristors is based on the Linear Drift Model. In the Linear Drift Model the resistance of the doped region increases in direct proportion to the width of the doped region. It is shown that this is not consistent with the physical conservation of the mobile vacancies. A circuit model is proposed which is consistent with the conservation of the mobile vacancies and takes into account a high constant intrinsic resistivity indicative of the memristor “off state”. A numerical analysis (NA) scheme is tested and compared with reported Hewlett Packard memristor data and with the theoretical solution for the Linear Drift Model. View full abstract»

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  • The use of error correcting codes for nanoelectronic systems: Overview and future prospects

    Page(s): 51 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB) |  | HTML iconHTML  

    As CMOS devices scale to the very deep submicron (VDSM) regime they become more susceptible to transient faults such as memory bit flips due to alpha particles as well as permanent faults due to manufacturing issues. As the transition is made to emerging nanotechnologies, such as carbon nanotube transistors, the reliability of the electronic components will increasingly become a critical concern. One important solution is to borrow an idea from communication theory and use error correcting codes to improve performance. The interconnect or logic circuitry are analogous to a noisy communication channel. The use of error correcting codes (ECCs) has the potential to improve the computational capacity of the nanoscale circuitry and wires. This paper will survey the field of proposed solutions for use of ECCs in the area of interconnect and logic circuits. Discussion of the current state-of-the-art approaches is provided and some suggestions for future work for making ECCs a viable method of improving the performance of nanoelectronic systems is given. View full abstract»

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