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Circuit Theory, IEEE Transactions on

Issue 4 • Date July 1971

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Displaying Results 1 - 19 of 19
  • On constant delay approximations for commensurate transmission-line filters

    Publication Year: 1971 , Page(s): 485 - 488
    Cited by:  Papers (1)
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  • Analysis of an adjustable multipath network for use in building out transmission-line skin-effect losses

    Publication Year: 1971 , Page(s): 436 - 443
    Cited by:  Papers (2)
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    In wide-band repeatered coaxial transmission systems, the dominant loss due to skin effect of the cable varies with temperature and cable length. Line-build-out (LBO) networks, whose attenuation characteristics match various amounts of cable losses, are inserted to yield a fixed loss characteristic between repeaters. A multipath structure is proposed as a new means of realizing adjustable LBO networks. Variation of the proposed structure is accomplished through electronically controlled variable gain amplifiers, allowing precise setting of the build-out. The transmission characteristics of the paths can be realized with either lumped circuit elements or distributed networks, as the frequency of interest might dictate. The amplifier gain variation performs an interpolation among the transfer functions of the different paths. The theoretical upper limit of the usable adjustment range is determined by the tolerance on the inaccuracies of the interpolation process. The two-path (II-path) configuration appears to be the easiest to realize, while providing enough adjustable range and accuracy to be of practical interest to both digital and analog wide-band repeatered systems. In the baseband PCM application, simulation shows that a 7-dB adjustable range, at the half pulse rate, is feasible with only 0.9-percent pulse distortion. View full abstract»

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  • Conditions for a minimax optimum

    Publication Year: 1971 , Page(s): 476 - 479
    Cited by:  Papers (16)
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    This paper derives and discusses necessary conditions for an optimum in nonlinear minimax approximation problems. A straightforward geometrical interpretation is presented. The results may be used to test for convergence in computer-aided network optimization, in tests for optimality in the Chebyshev sense of any given design, and to gain insight which may be helpful in developing minimax approximation algorithms. View full abstract»

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  • Parasitics and the stability of equilibrium points of nonlinear networks

    Publication Year: 1971 , Page(s): 481 - 484
    Cited by:  Papers (3)
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    The stability of equilibrium points of autonomous nonlinear networks with parasitics is presented. Conditions are given under which the behavior of the parasitic network is approximated by the simplified network without parasitics. More precisely, criteria are provided for which, if the parasitics are sufficiently small, the stability (instability) of the simplified network implies the stability (instability) of the network with parasitics. View full abstract»

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  • Invariance properties of central trees

    Publication Year: 1971 , Page(s): 465 - 467
    Cited by:  Papers (5)
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    Invariance properties of central trees are investigated with respect to four operations: deleting, adding, contracting, and inserting. The results obtained seem to be useful for theoretical and practical purposes such as investigating topological properties of reduced or extended graphs and finding central trees of large graphs. View full abstract»

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  • A numerical solution of the state equation of an energy converter with time-varying coefficients

    Publication Year: 1971 , Page(s): 467 - 469
    Cited by:  Papers (1)
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    A rotary energy converter is viewed as a dynamic coupled circuit. Its equation of motion is formulated as a state-vector differential equation with time-varying coefficients. A numerical method of solving the state equation with time-varying coefficients is then presented and an example is considered to illustrate the procedure. View full abstract»

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  • Synthesis of a resistively terminated cascade of uniform lossless transmission lines and lumped passive lossless two-ports

    Publication Year: 1971 , Page(s): 444 - 455
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1280 KB)  

    This paper presents a general solution to the problem of synthesizing a passive two-port consisting of a cascade of uniform lossless transmission lines, commensurable or incommensurable, and lumped passive lossless two-ports in an arbitrary sequence with a resistive termination at the receiving end. After a basic discussion is given on the foundation of the multivariable synthesis of networks composed of uniform lossless transmission lines and lumped passive elements, the necessary and sufficient condition is given on the scattering function for it to be realizable as a cascade network. Based on this result, some special cases of the problem are discussed. Further, the equivalence of the multivariable and frequency-domain approaches to the above-mentioned problem is established. View full abstract»

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  • Proof of the Chua conjecture on LTC-realizable resistive n-ports

    Publication Year: 1971 , Page(s): 484 - 485
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    In a recent paper Chua proved that a large class of voltage-controlled nonlinear resistive n -ports could be realized with the aid of a homeomorphic resistive n -port and a linear transformation converter (LTC) constructed of 2n negative linear resistors. He conjectured that only n such resistors are needed. In addition to proving this conjecture, we demonstrate that the n resistors need not be negative. View full abstract»

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  • Bicubic functions with real multiple poles and zeros

    Publication Year: 1971 , Page(s): 470 - 471
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    When Z(s) has one triple pole and one triple zero, i.e., Z(s)=(s+z)^{3}/(s+p)^{3} , a series-parallel RLC realization can be obtained using an extended form of the Guillemin technique. This synthesis, which eliminates the need for surplus factors and avoids minimization, proves to be appropriate for Z(s) within its entire positive real range. View full abstract»

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  • Realization of nonminimum phase transfer functions using twin-T RC networks

    Publication Year: 1971 , Page(s): 471 - 475
    Cited by:  Papers (3)
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    Realization of a second-order nonminimum phase transfer function using the Fialkow-Gerst two-port RC -network synthesis and analysis of the general twin- T RC network lead to the same design relations governing the element values. Sensitivity consideration shows the practical limitations on this circuit for a specific Q of the zeros and for a bounded spread in element values. View full abstract»

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  • On feasibility conditions of multicommodity flows in networks

    Publication Year: 1971 , Page(s): 425 - 429
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    An alternate derivation of the dual condition (called the severance-value condition in this paper) to feasibility of the multicommodity flow problem is given by graph theoretical arguments. That is, a multicommodity flow of given requirements is feasible if and only if the capacity of every severance is no less than its least capacity consumption for the flow. A severance is a set of the edges with nonnegative integer coefficients. Even when the severance-value condition is satisfied by a certain finite subset of severances, the multicommodity flow is shown to be still feasible if each requirement is allowed to be reduced by an appropriate amount \mu . This truncation allowance \mu is estimated in terms of the network topology and the capacity function. View full abstract»

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  • On the formal theory of nonuniform transmission lines

    Publication Year: 1971 , Page(s): 479 - 481
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    Some results are given in the formal theory of nonuniform transmission lines whose constitutive parameters are bounded measurable functions of the geometric abscissa x and holomorphic functions of the complex variable p in some region D of the complex plane. View full abstract»

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  • A contribution to the theory of short-time spectral analysis with nonuniform bandwidth filters

    Publication Year: 1971 , Page(s): 455 - 460
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    The mathematical representation of the short-time spectral analysis is extended from the case of uniform bandpass filters (that is, filters having the same complex envelope) to the case of nonuniform filters (that is, filters whose complex envelope depends upon their center frequency). This leads to an integral transform, formally similar to the Fourier transform, where the signal taken up to the observation time appears weighted by a function (namely, the complex envelope) depending on the frequency of analysis. Of course, for every choice of such a complex envelope (or of the equivalent set of filters), one has a corresponding integral transform to deal with. The particular case of complex envelopes as functions of the time-frequency product is studied here because of its great physical interest (it applies, for instance, to many existing "real-time audio analyzers"). The corresponding integral transform is shown to have two remarkable properties: 1) it admits an inverse integral transform; 2) it is "form invariant" under linear time scaling of the signal, and no other integral transform (that is, no other class of complex envelopes, even frequency independent) shares this property. The physical significance of such results is discussed, together with some ideas for applications and further theoretical work. View full abstract»

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  • On the solvability of the equations of networks containing semiconductor devices, and reverse-bias breakdown phenomena

    Publication Year: 1971 , Page(s): 475 - 476
    Cited by:  Papers (1)
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  • Self-dual linear n-ports: A frequency-domain approach

    Publication Year: 1971 , Page(s): 469 - 470
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  • Effective bandwidth using L^2 norms

    Publication Year: 1971 , Page(s): 463 - 465
    Cited by:  Papers (8)
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    The effective bandwidth of a signal using an L^{2} norm is defined. Easily applied bounds on the effective bandwidth are determined. View full abstract»

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  • New Lagrangian and Hamiltonian functions for linear dissipative physical systems with ideal drivers

    Publication Year: 1971 , Page(s): 461 - 463
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    A new potential function is derived for dissipative physical systems with ideal drivers. The Lagrangian thus formulated satisfies the Euler-Lagrange equation, and the Hamiltonian thus derived satisfies the canonical-form Euler-Lagrange equation. State models can be obtained from a given system graph and vice versa if the state model is realizable. View full abstract»

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  • Decomposition of a graph into compactly connected two-terminal subgraphs

    Publication Year: 1971 , Page(s): 430 - 435
    Cited by:  Papers (1)
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    In the process of calculating the admittance matrix of a fairly large n -port network of n+q+1 nodes, we are often confronted with the problem of seeking that order of the pivotal condensations with respect to q internal ports of the primitive admittance matrix. Motivated by this problem, we discuss a method of decomposing a given graph.into "compactly connected" two-terminal subgraphs. The decomposition enables us to apply the block-pivoted condensation on the nodal admittance matrix. View full abstract»

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  • Restrictions on the effective bandwidth of signals

    Publication Year: 1971 , Page(s): 422 - 425
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The effective bandwidth of a signal is defined. Restrictions on the effective bandwidth are obtained. View full abstract»

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