Showing papers by "Mitre Corporation published in 1971"
TL;DR: In this paper, a matrix equation describing scattering for general incidence on objects of arbitrary shape is derived, with no losses present, and the scattering matrix is then obtained in the symmetric, unitary form.
Abstract: Upon defining vector spherical partial waves {${\mathbf{\ensuremath{\Psi}}}_{n}$} as a basis, a matrix equation is derived describing scattering for general incidence on objects of arbitrary shape. With no losses present, the scattering matrix is then obtained in the symmetric, unitary form $S=\ensuremath{-}{\stackrel{^}{Q}}^{\ensuremath{'}*}{\stackrel{^}{Q}}^{*}$, where (perfect conductor) $\stackrel{^}{Q}$ is the Schmidt orthogonalization of ${Q}_{n{n}^{\ensuremath{'}}}=(\frac{k}{\ensuremath{\pi}})\ensuremath{\int}d\mathbf{\ensuremath{\sigma}}\ifmmode\cdot\else\textperiodcentered\fi{}[(\ensuremath{
abla}\ifmmode\times\else\texttimes\fi{}\mathrm{Re}{\mathbf{\ensuremath{\Psi}}}_{n})\ifmmode\times\else\texttimes\fi{}{\mathbf{\ensuremath{\Psi}}}_{{n}^{\ensuremath{'}}}]$, integration extending over the object surface. For quadric (separable) surfaces, $Q$ itself becomes symmetric, effecting considerable simplification. A secular equation is given for constructing eigenfunctions of general objects. Finally, numerical results are presented and compared with experimental measurements.
1,015 citations
Book•
01 May 1971
100 citations
TL;DR: In this article, a direct procedure for obtaining a minimal realization of a multiple-input multiple-output linear time-invariant discrete system from observations of the input and output is presented.
Abstract: A direct procedure is presented for obtaining a minimal realization of a multiple-input multiple-output linear time-invariant discrete system from observations of the input and output. Discussion is limited to the case of noise-free observations in order to focus attention on the realization procedure and to display the structure of the resulting realization. This known structural form car be used as a check on the realization procedure. Application of the procedure requires knowledge of an upper bound on the minimal system dimension; however, a modification is given to handle the situation where an upper bound is not known. An example is included to show the operation of the procedure.
81 citations
Patent•
[...]
TL;DR: In this paper, a video information transfer and display system having a plurality of video display devices and apparatus to select for display at particular display devices, on the basis of identification data incorporated within the video signals, was presented.
Abstract: A video information transfer and display system having a plurality of video display devices and apparatus to select for display at particular display devices, on the basis of identification data incorporated within the video signals, predetermined video display information from sequential video signals also received at many other display sites. Video recorders are adapted to record selected portions of commercial television-type video signals and maintain the image displayed on associated television receivers.
56 citations
TL;DR: Computer analysis indicates the feasibility of single-stroke keying for data entry of alphabetic names using the standard touch-tone telephone pad.
Abstract: Computer analysis indicates the feasibility of single-stroke keying for data entry of alphabetic names using the standard touch-tone telephone pad. In many practical job situations little ambiguity...
52 citations
18 Oct 1971
TL;DR: The Venus Operating System as mentioned in this paper is an experimental multiprogramming system which supports five or six concurrent users on a small computer and was developed to test the effect of machine architecture on complexity of software.
Abstract: The Venus Operating System is an experimental multiprogramming system which supports five or six concurrent users on a small computer. The system was produced to test the effect of machine architecture on complexity of software. The system is defined by a combination of micro-programs and software. The microprogram defines a machine with some unusual architectural features; the software exploits these features to define the operating system as simply as possible. In this paper the development of the system is described, with particular emphasis on the principles which guided the design.
43 citations
TL;DR: It is concluded that for visual search tasks of the kind reported here, there is no marked deleterious effect of blink coding on symbol legibility, and no marked interference attributable to irrelevant blink.
Abstract: TEN MEN SCANNED CATHODE-RAY-TUBE DISPLAYS TO SEARCH FOR DESIGNATED TARGET ITEMS. SEARCH TIME INCREASED WITH INCREASING DISPLAY DENSITY, AND WAS 50% FASTER WHEN A 3-CPS BLINK WAS IMPOSED ON ITEMS OF THE TARGET CLASS. THE BLINKING OF NONTARGET ITEMS WAS ALMOST EQUALLY EFFECTIVE, INDICATING THAT BLINK CAN BE USED EITHER AS AN INCLUSION OR EXCLUSION CODE. IN COMPARISON WITH STEADY, NONBLINKING DISPLAYS, SEARCH TIME WAS NOT SIGNIFICANTLY DIFFERENT FOR DISPLAYS IN WHICH ALL ITEMS BLINKED, OR IN WHICH A RANDOM SELECTION OF ITEMS BLINKED. IT IS CONCLUDED THAT FOR VISUAL SEARCH TASKS OF THE KIND REPORTED, THERE IS NO MARKED DELETERIOUS EFFECT OF BLINK CODING ON SYMBOL LEGIBILITY, AND NO MARKED INTERFERENCE ATTRIBUTABLE TO IRRELEVANT BLINK. /AUTHOR/
31 citations
TL;DR: An iterative labeling algorithm is developed to determine the most vital link in the network and a necessary condition for an arc to be themost vital link is established and is employed to decrease the number of arcs which must be considered.
Abstract: : The most vital link in a single commodity flow network is that arc whose removal results in the greatest reduction in the value of the maximal flow in the network between a source node and a sink node. This paper develops an iterative labeling algorithm to determine the most vital link in the network. A necessary condition for an arc to be the most vital link is established and is employed to decrease the number of arcs which must be considered.
30 citations
26 citations
TL;DR: It is shown that aperiodic sampling is not always more efficient than periodic sampling, and if the input and statistics of the input disturbance are not known a priori, then the best sampling efficiency is obtained using periodic sampling.
Abstract: Selected adaptive sampling control laws are compared with periodic sampling for five different inputs. It is shown that 1) aperiodic sampling is not always more efficient than periodic sampling, and 2) if the input and statistics of the input disturbance are not known a priori, then the best sampling efficiency is obtained using periodic sampling.
21 citations
TL;DR: The adaptive codes are shown to perform better than nonadaptive codes, although the difference is less significant for convolutional codes, and the convolutionAL codes give better performance than nonconcatenated block codes.
Abstract: Four forward error correction techniques are examined and their performance compared on several real channels. Techniques of both adaptive and nonadaptive block and convolutional coding are examined. The Golay code is considered in a randomerror correcting mode and in an adaptive burst-random modes. Both versions employ interleaving as an added error correction aid. The adaptive convolutional code is a diffuse threshold-decoded Gallager code requiring a variable guard space, while the nonadaptive is a Massey code. The codes are commonly used rate 1/2 codes. The codes are evaluated and compared on three channels: a transcontinental HF 4800 bit/s channel between San Diego, Calif., and Bedford, Mass.; a mixed wireline microwave troposcatter 2400 bit/s channel dominated by a 583-mi troposcatter hop; and a 2400 bit/s satellite communications circuit from Ascension Island to Andover, Me., with wireline transmission from Andover, Me., to Greenbelt, Md. All three channels exhibit burst errors with the error rate decreasing and the burst error density increasing in the order in which channels were identified. The adaptive codes are shown to perform better than nonadaptive codes, although the difference is less significant for convolutional codes. Furthermore, the convolutional codes give better performance than nonconcatenated block codes.
TL;DR: The Amazon River outflow during the spring rainy season is detected in the Atlantic Ocean far from its source as mentioned in this paper, and radio message data from ocean stations taken during BOMEX 1969 indicate the vast extent of the water mass.
Abstract: The Amazon River outflow during the spring rainy season is detected in the Atlantic Ocean far from its source. Radio message data from ocean stations taken during BOMEX 1969 indicate the vast extent of the water mass. The fresh water on the surface permits a warm stable layer to exist below the surface.
TL;DR: The performance of a frame-synchronisation technique for use with binary data transmission is analysed on the binary symmetric channel, which can be used to represent a space channel or any data link to which a message-interleaving or diffusion scheme has been applied.
Abstract: The performance of a frame-synchronisation technique for use with binary data transmission is analysed on the binary symmetric channel. Although the binary symmetric channel is an idealised channel, it can be used to represent a space channel or any data link to which a message-interleaving or diffusion scheme has been applied.
01 Feb 1971
TL;DR: In this paper, a radar system for imaging a spetially limited object at long range is described, which consists of a large array (100 km square) of widely separated receivers, each containg its own local oscillator.
Abstract: A radar system for imaging a spetially limited object at long range is described. The geometry consists of a large array (100 km square) of widely separated receivers, each containg its own local oscillator. The reference signal is derived by scattering a low-frequency wave from the object.
TL;DR: In this paper, a diffraction-limited, electromagnetic theory of image formation is presented for a point-reference hologram whose recording arrangement consists of a surface of arbitrary shape, a point reference source, and the object.
Abstract: A diffraction-limited, electromagnetic theory of image formation is presented for a point-reference hologram whose recording arrangement consists of a surface of arbitrary shape, a point-reference source, and the object. The hologram is illuminated by a spherical electromagnetic wave during reconstruction. The electromagnetic hologram is assumed to have recorded two components of the field scattered from the object so that the vector field is completely reconstructed. The vector hologram is modeled by electric and magnetic surface currents determined from the irradiance of each of two orthogonal components of the object field on the film. The image field is described by a dyadic kernel, the system response to a point object, which is related to the scalar kernel by Π(r,r′) = DK(r,r′), where D is the dyadic operator D= (I+k−2∇∇). It is shown that the conjugate-image field produced by a point-reference electromagnetic hologram approximates the field produced by the ideal system, which forms the image of a point object by launching a spherically converging wave.
TL;DR: A modeling study of atmospheric diffusion indicates that emission from power plants contributed only a modest percentage of the yearly average concentration of sulfur dioxide at ground level in the most polluted areas of Cook County, Illinois, during 1968.
Abstract: A modeling study of atmospheric diffusion indicates that emission from power plants contributed only a modest percentage of the yearly average concentration of sulfur dioxide at ground level in the most polluted areas of Cook County, Illinois, during 1968.
TL;DR: A digital computer solution of the state- variable equations was obtained to verify the accuracy and tractability of the mathematical model of the diode for the analysis of nonideal poly phase converters.
Abstract: The mathematical model of the diode proposed in this investigation for the analysis of nonideal poly phase converters has finite forward and reverse resistances. Since current-dependent diode impedances exist at all times, only one set of piecewise-linear time-invariant state-variable equations is required to describe the nonideal polyphase diode converter completely. A digital computer solution of the state- variable equations was obtained to verify the inte grity and tractability of this method of analysis.
TL;DR: An optimization of the PLL loop parameters is obtained using computer techniques and this model is used to optimize parameters and investigate pull-in performance.
TL;DR: In this article, the problem of the current-algebra treatment of the decay of a meson into three mesons is analyzed within the framework of a nonlinear Lagrangian calculation based on the chiral group.
Abstract: The difficulties with the current-algebra treatment of the decay of the $\ensuremath{\eta}$ meson into three $\ensuremath{\pi}$ mesons are analyzed within the framework of a nonlinear Lagrangian calculation based on the chiral group $\mathrm{SU}(3)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(3)$. The most general $\ensuremath{\eta}$-decay Lagrangian with the symmetry properties of the effective second-order electromagnetic interaction, and containing no more than two derivaties, is constructed and is shown to involve only one arbitrary parameter, the coupling constant $g$. The energy dependence, or slope, of the $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ matrix element depends only on the choice of representation for the $\mathrm{SU}(3)$ and $\mathrm{SU}(3)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(3)$ (collectively called medium-strong) symmetry-breaking terms. The simplest choice for these terms in a theory containing explicit partial conservation of axial-vector current \char22{} namely, a common $(3,\overline{3})+(\overline{3},3)$ representation for both \char22{} gives good agreement with experiment, Furthermore, exactly three parameters exist for adjusting the coupling constant and the electromagnetic mass differences $m_{{\ensuremath{\pi}}^{+}}^{}{}_{}{}^{2}\ensuremath{-}m_{{\ensuremath{\pi}}^{0}}^{}{}_{}{}^{2}$ and $m_{{K}^{+}}^{}{}_{}{}^{2}\ensuremath{-}m_{{K}^{0}}^{}{}_{}{}^{2}$ to their measured values. However, the coefficients of terms in the resulting phenomenological Lagrangian are unnaturally large; they give rise to the small mass differences only because of extensive cancellations (a condition which we refer to as a "scale difficulty"). The same techniques used for $\ensuremath{\eta}$ decay are also applied to the nonleptonic weak decays of the $K$ mesons. The usual current-algebra results are obtained as a check that our methods are exactly equivalent to the conventional ones.
01 Feb 1971
TL;DR: In this article, an analysis of crosstalk between the quadrature components of a bandpass signal when passed through a band-pass filter is presented, and the CIR is defined and used as an evaluation criterion.
Abstract: An analysis of crosstalk between the quadrature components of a bandpass signal when passed through a bandpass filter is presented. The crosstalk interference ratio (CIR) is defined and used as an evaluation criterion.
01 Jan 1971
TL;DR: A technique for data transmission using basis waveforms in a Euclidean space is presented and an example is used to demonstrate that this technique can give performance superior to that of the duobinary technique.
Abstract: A technique for data transmission using basis waveforms in a Euclidean space is presented. An example is used to demonstrate that this technique can give performance superior to that of the duobinary technique.
16 Aug 1971
TL;DR: The object is to obtain an adequate mathematical model for the PLL and then to use this model to optimize parameters and investi gate pull-in performance.
Abstract: The automatic control and simulation of phased- locked loops (PLL) is treated with particular em phasis on the use of analog and digital computer simulation techniques. The object is to obtain an adequate mathematical model for the PLL and then to use this model to optimize parameters and investi gate pull-in performance. Results are presented for the second-order loop, with ramp, step, random noise, and sinusoidal inputs.The significant result is that an optimization of the PLL loop parameters is obtained using computer techniques.
TL;DR: The authors describe some publication managers who fail the test and become a drain on corporate management in vestment, describing managers who "innaugurate change to compensate for change." But this article also describes some managers who do not adapt well to change.
Abstract: One's openness to, and ability to cope with, change are measured by the acid test for publication specialists described here. The winners "innaugurate change to compensate for change." But this article also describes some publication managers who fail the test and become a drain on corporate management in vestment.