By Topic

Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on

Issue 5 • Date May 1998

Filter Results

Displaying Results 1 - 15 of 15
  • A DTCNN universal machine based on highly parallel 2-D cellular automata CAM2

    Page(s): 538 - 546
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The discrete-time cellular neural network (DTCNN) is a promising computer paradigm that fuses artificial neural networks with the concept of cellular automaton (CA) and has many applications to pixel-level image processing. Although some architectures have been proposed for processing DTCNN, there are no compact, practical computers that can process real-world images of several hundred thousand pixels at video rates. So, in spite of its great potential, DTCNNs are not being used for image processing outside the laboratory. This paper proposes a DTCNN processing method based on a highly parallel two-dimensional (2-D) cellular automata called CAM2. CAM2 can attain pixel-order parallelism on a single PC board because it is composed of a content addressable memory (CAM), which makes it possible to embed enormous numbers of processing elements, corresponding to CA cells, onto one VLSI chip. A new mapping method utilizes maskable search and parallel and partial write commands of CAM2 to enable high-performance DTCNN processing. Evaluation results show that, on average, CAM2 can perform one transition for various DTCNN templates in about 12 microseconds. Also it can perform practical image processing through a combination of DTCNNs and other CA-based algorithms. CAM2 is a promising platform for processing DTCNN View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New sufficient conditions for absolute stability of neural networks

    Page(s): 584 - 586
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    The main result obtained in this paper is that for a neural network with interconnection matrix T, if -T is quasi-diagonally row-sum or column-sum dominant, then the network system is absolutely stable. The above two sufficient conditions for absolute stability are independent of the existing sufficient ones in the literature. Under either of the above two sufficient conditions for absolute stability, the vector field defined by the network system is also structurally stable View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Canonical piecewise-linear approximation of smooth functions

    Page(s): 567 - 571
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    This paper deals with the approximation of smooth functions using canonical piecewise-linear functions. The developing of tools in the field of analysis and control of nonlinear systems based on this kind of functions, as well as its efficiency in the representation of electronic devices, motivates the development of useful methods to obtain accurate approximations. A recursive method is proposed to obtain simultaneously all the parameters required and its convergence is studied. In addition, an iterative method to introduce new partitions on the domain, when the error obtained is not satisfactory, is described. This method takes advantage of the partitions already found to reduce the total number of parameters that the algorithm has to handle View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the analysis of sorting networks from the viewpoint of circuit theory

    Page(s): 591 - 593
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB)  

    A sorting network is the kernel of an order statistics-based filter and contains all information about the nonlinearity. Its implementation is simple; its analysis, however, is relatively difficult due to the hiding of the nonlinearity. In this short paper, we analyze a sorting network from the viewpoint of classical circuit theory, and reveal its relation to a nonlinear lossless n-port. We show that a sorting network is in fact the wave digital filter (WDF) realization of an n-port memoryless nonlinear classical network. Hence, it can be unified to the group of nonlinear WDF networks. Useful properties such as passivity and losslessness are hence inherent properties of such networks View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A representation theorem for linear systems

    Page(s): 578 - 580
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    The cornerstone of the theory of discrete-time single-input single-output linear systems is the idea that every such system has an input-output map H that can be represented by a convolution or the familiar generalization of a convolution. This thinking involves an oversight that was recently corrected by adding an additional term to the representation. Here we give a corresponding result for the important case of representations of causal continuous-time system maps that take bounded functions into bounded functions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simplified thermal analysis approach for power transistor rating in PWM-controlled DC/AC converters

    Page(s): 557 - 566
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A simplified dynamic thermal analysis approach is proposed for the estimation of the peak junction temperature in power IGBT transistors operating in pulse-width modulation (PWM) controlled DC/AC converters. This approach can be used for the rating of electron devices or heatsink systems in power circuit design, as it provides a direct analytical link, in terms of electrical and thermal device parameters and converter operating conditions between the case and the peak junction temperatures. In this way, by imposing a given upper limit on the junction temperature, indirect constraints on device size or load current or heatsink efficiency can easily be obtained. The approach is based on mild, pessimistic approximations on both the spectrum of dissipated power and on the dynamic thermal behavior of the device. The validity of such approximations has been verified by comparison with the results of accurate numerical simulations carried out by using measurement-based loss models. Possible ways of using this approach in a converter rating context are outlined in the paper, by considering different design scenarios View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Lyapunov stability of two-dimensional digital filters with overflow nonlinearities

    Page(s): 574 - 577
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    In this paper, the second method of Lyapunov is utilized to establish sufficient conditions for the global asymptotic stability of the trivial solution of zero-input two-dimensional (2-D) Fornasini-Marchesini state-space digital filters which are endowed with a general class of overflow nonlinearities. Results for the global asymptotic stability of the null solution of the 2-D Fornasini-Marchesini second model with overflow nonlinearities are established. Several classes of Lyapunov functions are used in establishing the present results, including vector norms and the quadratic form. When the quadratic form Lyapunov functions are considered, the present results involve necessary and sufficient conditions under which positive definite matrices can be used to generate Lyapunov functions for 2-D digital filters with overflow nonlinearities View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comment on “Comments on `Necessary and sufficient condition for absolute stability of neural networks'”

    Page(s): 595 - 596
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (92 KB)  

    This letter points out that a new majorization of the derivative of the Lyapunov function used in the above letter [see ibid., vol.42, p.497-9, 1995] gives a new, weaker condition on the interconnection matrix that is sufficient for the global asymptotic stability (GAS) of the equilibrium point for dynamical neural networks. The result also includes some earlier results derived in the literature View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A differential integrator with a built-in high-frequency compensation

    Page(s): 517 - 522
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    A novel integrator with differential inputs is described. The integrator uses a single RC network to control the integration action of the circuit. It performs at higher frequencies with higher quality factors than the traditional differential integrator. Simulation and experimental results support the theoretical derivations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A direct learning law for a class of auto-associative dynamic neural networks

    Page(s): 580 - 583
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    This paper proposes a new learning technique fur a class of additive dynamic auto-associative neural networks. In the proposed technique, which is based on the Jurdjevic-Quinn stabilization method for control affine systems, the network synaptic weights are directly related to the network states. Asymptotic stability of the training law is assured and a region of attraction around each point attractor can be predefined. The proposed learning law is simpler than existing techniques and requires the solution of significantly fewer nonlinear differential equations. The proposed technique is compared with existing techniques by way of an example View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An analytical solution for a class of oscillators, and its application to filter tuning

    Page(s): 547 - 556
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    We present a completely analytical solution to a filter-comparator oscillator system, and verify it by macromodel simulations and experiment. We discuss the applications of this kind of oscillator in a vector-locked loop system for continuous time filter tuning. We also apply our solution to the operation of a resonant switched mode inverter View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic properties of cellular neural networks with nonlinear output function

    Page(s): 587 - 590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    Cellular neural networks are a novel class of information-processing systems which have architecture similar to neural networks. In this short paper, we consider a nonlinear cellular neural network where the nonlinearity in the feedback circuit is allowed to exhibit hysteresis. Stability analysis of the equilibrium points for such a network is made. Hopf-like bifurcations are proved for an example of a two-cell autonomous cellular neural network View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the characterization and reduction of distortion in bandpass filters

    Page(s): 523 - 537
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    In this paper we consider the nonlinear mixing products that arise and cause distortion in weakly nonlinear bandpass filters that might be used in a radio receiver. Volterra series analysis is applied to a Gm-C filter with weak cubic nonlinearities in the transconductance amplifiers so that explicit formulae for the amplitudes of the mixing products can be derived and an architecture for the reduction of distortion proposed, The analysis is used to aid in the characterization of distortion in practice, both in SPICE simulation and laboratory work View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimation of the basin of attractions in CNNs

    Page(s): 571 - 574
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    A technique is discussed in order to find an estimation of the basin of attraction for each stable equilibrium point in cellular neural networks. The technique is based on the determination of the direction of the trajectories for each of the regions in which the state space is divided via the piecewise linear output function of each cell View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comment on “Comments on `Necessary and sufficient condition for absolute stability of neural networks'”

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    This letter points out that a statement in the above letter [see ibid., vol.42, p.497-9, 1995] saying that the sufficiency part of absolute stability result on neural networks includes the sufficiency part of the absolute stability result in Forti et al. [see Proc. 1994 IEEE Int. Symp. Circuits Systems, p.241-4, April 1994], is not correct under the stated conditions. On the other hand, it is shown that the sufficiency part of absolute stability result in Forti et al. is included by the sufficiency part of a conjecture stated in the above letter View full abstract»

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