Showing papers by "IBM published in 1972"

A Class of Algorithms for Fast Digital Image Registration

Abstract: The automatic determination of local similarity between two structured data sets is fundamental to the disciplines of pattern recognition and image processing. A class of algorithms, which may be used to determine similarity in a far more efficient manner than methods currently in use, is introduced in this paper. There may be a saving of computation time of two orders of magnitude or more by adopting this new approach. The problem of translational image registration, used for an example throughout, is discussed and the problems with the most widely used method-correlation explained. Simple implementations of the new algorithms are introduced to motivate the basic idea of their structure. Real data from ITOS-1 satellites are presented to give meaningful empirical justification for theoretical predictions.

Atomic coherent states in quantum optics

Abstract: The central problem of Quantum Optics (laser theory, super-radiance, resonant propagation, etc.) is the description of the interaction between N atoms and an electromagnetic field confined in a cavity of finite volume. A suitable model Hamiltonian for this problem is the following one (ℏ = 1) $$\begin{array}{*{20}{l}} {{\rm{H = }}\sum\limits_{\rm{k}} {{{\rm{\omega }}_{\rm{k}}}} {\rm{a}}_{\rm{k}}^{\rm{ + }}{{\rm{a}}_{\rm{k}}}{\rm{ + }}\frac{{{{\rm{\omega }}_{\rm{o}}}}}{{\rm{2}}}\sum\limits_{{\rm{i = 1}}}^{\rm{N}} {{{\rm{S}}_{{\rm{3}}\left( {\rm{i}} \right)}}} }\\ {{\rm{ + }}\sum\limits_{{\rm{k,i}}} {{{\rm{g}}_{\rm{k}}}\left( {{{\rm{a}}_{\rm{k}}}{\rm{S}}_{\rm{i}}^{\rm{ + }}{{\rm{e}}^{{\rm{i \bullet }}{{{\rm{}}}_{\rm{i}}}}}{\rm{ + a}}_{\rm{k}}^{\rm{ + }}{\rm{S}}_{\rm{i}}^{\rm{ - }}{{\rm{e}}^{{\rm{ - i \bullet }}{{{\rm{}}}_{\rm{i}}}}}} \right)} {\rm{,}}} \end{array}$$ where ak, a k + are Bose operators describing the k-th field mode and S i ± ,S3i are Pauli operators describing the atom located at position x i as a two-level system.

Self-Consistent Results for n -Type Si Inversion Layers

Abstract: Self-consistent results for energy levels, populations, and charge distributions are given for $n$-type inversion layers on $p$-type silicon. Quantum effects are taken into account in the effective-mass approximation, and the envelope wave function is assumed to vanish at the surface. Approximate analytic results are given for some special cases. Numerical results are given for representative surface orientations, bulk acceptor concentrations, inversion-layer electron concentrations, and temperatures.

Models for contacts to planar devices

Abstract: Two basic models for rectangular contacts to planar devices, the Kennedy-Murley Model (KMM) and the Transmission Line Model (TLM) are discussed and compared. The KMM does not take into account the interface resistance between metal and semiconductor, whereas the TLM disregards the vertical structure of the semiconductor layer. An extension of the TLM is derived (ETLM), which approximately considers this vertical structure. KMM and TLM thus appear as special cases of the ETLM. The calibration of the latter on the KMM then yields a simple quantitative criterion for the applicability of the KMM or the pure TLM. Measurement results on typical aluminum-silicon contacts are described satisfactorily by the (E)TLM. Concurrently with the applicability criterion, the KMM proves inadequate for these contacts due to the disregard of interface resistance. Conclusions are derived from the TLM pertaining to current distribution over the contact area and to contact resistance. In particular, the contacts are classified according to their operation mode. Finally, the TLM approach is applied also to circular contacts.

Inductance calculations in a complex integrated circuit environment

Abstract: This paper describes a method for calculating multiloop inductances formed by complicated interconnection conductors. Knowledge of these inductances leads to useful information concerning the design of such systems. In the approach pursued here, the conductor loops are divided into segments for which so-called partial inductances are calculated. The partial inductancens are then appropriately added to yield the desired loop inductance.

Atomic Coherent States in Quantum Optics

Abstract: For the description of an assembly of two-level atoms, atomic coherent states can be defined which have properties analogous to those of the field coherent states. The analogy is not fortuitous, but is shown to be related to the group contraction of exponential operators based on the angular momentum algebra to exponential operators based on the harmonic-oscillator algebra. The derivation of the properties of the atomic coherent states is made easier by the use of a powerful disentangling theorem for exponential angular momentum operators. A complete labeling of the atomic states is developed and many of their properties are studied. In particular it is shown that the atomic coherent states are the quantum analogs of classical dipoles, and that they can be produced by classical fields.

Complementary sets of sequences

Abstract: A set of equally long finite sequences, the elements of which are either + 1 or - 1, is said to be a complementary set of sequences if the sum of autocorrelation functions of the sequences in that set is zero except for a zero-shift term. A complementary set of sequences is said to be a mate of another set if the sum of the cross-correlation functions of the corresponding sequences in these two sets is zero everywhere. Complementary sets of sequences are said to be mutually orthogonal complementary sets if any two of them are mates to each other. In this paper we discuss the properties of such complementary sets of sequences. Algorithms for synthesizing new sets from a given set are given. Recursive formulas for constructing mutually orthogonal complementary sets are presented. It is shown that matrices consisting of mutually orthogonal complementary sets of sequences can be used as operators so as to per form transformations and inverse transformations on a one- or two-dimensional array of real time or spatial functions. The similarity between such new transformations and the Hadamard transformation suggests applications of such new transformations to signal processing and image coding.

Nematic-Liquid-Crystal Order—A Monte Carlo Calculation

Abstract: The lattice version of the Maier-Saupe model of a nematic liquid crystal, in which all molecules are restricted to be on a simple-cubic lattice with periodic boundary conditions and to interact only with their nearest neighbors through the interaction energy ${E}_{\mathrm{ij}}=\ensuremath{-}\ensuremath{\epsilon}(\frac{3}{2}{{cos}^{2}\ensuremath{\theta}}_{\mathrm{ij}}\ensuremath{-}\frac{1}{2})$, is investigated using a Monte Carlo technique. The lattice is found to undergo a first-order phase transition at $\frac{\ensuremath{\epsilon}}{\mathrm{kT}}=0.890\ifmmode\pm\else\textpm\fi{}0.005$ with a spontaneous order of $〈{P}_{2}(cos\ensuremath{\theta})〉=0.33\ifmmode\pm\else\textpm\fi{}0.04$ at the transition.

Uniform tag sequences

Abstract: Structural properties, local and asymptotic, of members of a class of simple, realtime generable sequences are analyzed.

Contact Resistance and Contact Resistivity

Abstract: This paper mainly offers guidance to the technologist who has to characterize metal‐semiconductor contacts for process development and production control. To abolish confusion clear definitions are proposed for the terms contact resistance and contact resistivity. Based on these definitions, methods of determining contact resistivity are discussed, revealing the common source of error of the methods and making comparisons. New methods like the TLM method are described and included in the comparison. Results of contact resistivity measurements on Al‐Si contacts over a wide range of silicon surface doping are presented.

Metal contact induced crystallization in films of amorphous silicon and germanium

Abstract: The crystallization and compound formation temperature of vacuum deposited amorphous Si (and Ge) while in contact with various crystalline metals as a thin film sandwich are investigated by electron microscopy and electron diffraction. The results show that in simple eutectic systems the Si crystallizes at 0.72 (and Ge at approximately 0.65) of the eutectic temperature expressed in degrees Kelvin. Compounds are formed generally by the more rapid diffusion of Si into the metal.

Distribution functions of multi-component fluid mixtures of hard spheres

Abstract: A simple algorithm for obtaining accurate pair distribution functions gij of hard-sphere mixtures is proposed. This generalizes the pure-fluid procedure of Verlet and Weis for improving the Percus-Yevick distribution functions. Two theorems are proved concerning the distribution functions yij =exp (uij/kT)gij , and an approximation for these functions is proposed. Finally, a method for computing direct correlation functions, given the pair distribution functions, is described.

Some continuous functions related to corner polyhedra, II

Abstract: The group problem on the unit interval is developed, with and without continuous variables The connection with cutting planes, or valid inequalities, is reviewed Certain desirable properties of valid inequalities, such as minimality and extremality are developed, and the connection between valid inequalities for P(I, u0) and P-+(I, u0) is developed A class of functions is shown to give extreme valid inequalities for P-+(I, u0) and for certain subsetsU ofI A method is used to generate such functions These functions give faces of certain corner polyhedra Other functions which do not immediately give extreme valid inequalities are altered to construct a class of faces for certain corner polyhedra This class of faces grows exponentially as the size of the group grows

Analysis and Design of Reliable Computer Networks

Abstract: In the design of a computer network, one of the fundamental considerations is the reliability and availability of the communication paths between all pairs of centers in the network. These characteristics are strongly dependent on the topological layout of the communication links in addition to the reliability and availability of the individual computer systems and communication facilities. Based on graph theoretic models for computer and communication networks, many different reliability measures have been defined. Attempts have been made to characterize networks that are optimal with respect to these measures. In this paper, the most significant reliability criteria and their relevance to different applications will be discussed. Furthermore, we survey the status of current research on the different criteria. The difficulties and limitations on each reliability measure will be pointed out and what seem to be the most fruitful areas for further investigation will be indicated.

Possible refinement of the lognormal hypothesis concerning the distribution of energy dissipation in intermittent turbulence

Abstract: Obukhov, Kolmogoroff and Yaglom, and in effect (independently) the geologist deWijs, have argued that energy dissipation in intermittent turbulence is lognormally distributed. However, this hypothesis will be shown to be probably untenable: depending upon the precise formulation chosen, it is either unverifiable or inconsistent.The present paper proposes a variant of the generating model leading to the lognormal.This variant is consistent, appears tractable, and for sufficiently small values of the parameter μ, (in Yaglom' s notation) it yields the lognormal hypothesis as a good approximation.As μ increases, the approximation worsens, and for high enough values of μ, turbulence ends by concentrating in very few huge “blobs”.Still other consistent alternative models of intermitt,ency yield distributions that diverge from the lognormal in the opposite direction; these various models in combination suggest several empirical tests.

A new efficient algorithm for solving differential-algebraic systems using implicit backward differentiation formulas

Abstract: The backward differentiation formulas (BDF), of order 1 up to 6 are described as they are applied to a system of differential algebraic equations. The BDF method is compared to the Gear-Nordsieck method, and is shown to be more efficient, more flexible in the selection of variables for prediction and error control, and more stable under conditions of rapidly varying Δt. For Δt fixed, the two methods are equivalent but for Δt varying they are not equivalent. Numerical experiments are described which demonstrate that the Gear-Nordsieck and BDF methods are unstable under rapidly changing Δt, but BDF is more stable. The two methods are distinguished numerically by identifying the modification of the Gear-Nordsieck method which makes it equivalent to the BDF method even if Δt changes. The computational advantage of using backward differences Δx, instead of the Nordsieck vector, for storing the backward-time information is treated by giving an operations count which shows the BDF using backward Δx's is more efficient. Finally, additional numerical evidence is given to support the use of variable order methods and the use of higher order methods.

CNO abundances and hydrodynamic models of the nova outburst.

Abstract: We have used a fully implicit, Lagrangian, hydrodynamic computer code incorporating a nuclear reaction network to follow thermonuclear runaways in the hydrogen-rich envelopes of white dwarfs in order to produce a nova outburst. Because of the short time-scales and the high nuclear burning rates produced in our models, the nuclear reactions are far out of equilibrium and the beta-plus unstable nuclei become the most abundant nuclei in the envelope except for hydrogen and helium. Our models have ejected 1.00017 solar mass with kinetic energies of 8 times 10 to the 44-th power ergs, a value that agrees quite closely with the observed values for novae.

Recursive computational procedure for two-dimensional stock cutting

Abstract: A recursive algorithm is implemented to give high computational speeds in the solution of a cutting-stock problem. Optimal edge-to-edge cutting is shown to be achieved more easily by recursive programming than by conventional methods. The technique features preliminary discretization, which lowers the memory requirements in the computational procedure. A comparison is made between this recursive algorithm and two iterative algorithms previously given by Gilmore-Gomory. The limitations of the algorithms are discussed and some numerical results given.

Merged-transistor logic (MTL)-a low-cost bipolar logic concept

Abstract: The authors describe a novel bipolar logic featuring a direct injection of minority carriers into the switching transistor. MTL is based on inverters having decoupled multicollector outputs for the logical combinations. The devices are self-isolated and no ohmic load resistors are required. This is a key to monolithic logic chips of very high functional density and low power dissipation. On experimental chips an excellent power-delay product of 0.35 pJ has been measured. These experiments show that a density of 100 gates/mm/SUP 2/ can be achieved with present manufacturing tolerances (minimum dimensions: 0.3-mil metal line width, 0.15-mil spacing, 0.2/spl times/0.2-mil/SUP 2/ contact holes).

Optical Free Induction Decay

Abstract: A simple application of the Stark-pulse technique, developed by Brewer and Shoemaker, demonstrates optical free induction decay-the optical analog of free induction decay in NMR. A molecular sample which is coherently prepared by a cw laser beam exhibits such a decay when it is suddenly switched out of resonance by a Stark field. Observations are presented for a nondegenerate Doppler-broadened infrared transition of N${\mathrm{H}}_{2}$D, where the sample is optically thin, and the decay behavior can be compared quantitatively with a solution of the Bloch equations. When the molecular sample is prepared under steady-state conditions, the solutions are analytic; for pulse excitation, a numerical solution is required. The treatment invokes a hard-collision relaxation model. Such characteristics as the abrupt termination of the decay and the related edge echo, which result from Doppler dephasing, can be examined for Stark pulses of finite extent.

Theory on the speed of convergence in adaptive equalizers for digital communication

Abstract: This paper presents an analysis of the convergence properties of adaptive transversal equalizers minimizing mean-square distortion. The intention is to reveal the influence on the speed of convergence exerted by the number of taps, the step-size parameter in the adjustment loops, and the spectrum of the unequalized signal. Attention is focused on the convergence of the expected mean-square distortion. Several approximations are made in the analysis, among them the approximation of higher-order statistics by second-order statistical parameters. Comparison with results obtained by computer simulation, however, shows that the theory developed renders a quite accurate picture of the convergence process. Previous work in this field demonstrated the limits set to the speed of convergence by the extreme values of the power spectrum of the unequalized signal. It is shown here that, with regard to the mean-square distortion, the influence of the number of taps will usually dominate by far. The theory provides a simple criterion for convergence and answers the question of how to attain the fastest convergence.

Rationale, limitations, and assumptions of a northeastern forest growth simulator

Abstract: A cooperative agreement between Yale University and the 1970 summer program of the IBM Research Division resulted in a flexible computer program to simulate the growth of the uneven-aged, mixed-species stands of trees on the 10-meter by 10-meter experimental plots of the Hubbard Brook Ecosystem Study in the White Mountains of northern New Hampshire. Annual increments of tree growth are based on species, tree size, and allocation of available light among the competing trees of the plot. Site quality differences between plots are assigned primarily by the concept of tree-growing degree-days, although soil moisture storage during the growing season and plot rockiness are also considered. Species succession, individual tree suppression and release, and other dynamic properties of forest stands have been successfully reproduced using the program. Additional field measurements are needed to further verify the model and to extend its applicability to nutrient cycling and other aspects of the Hubbard Brook Ecosystem Study. We believe that the simulator could readily be extended to include most other tree species of northeastern North America and also to match data from other sites through appropriate adjustment of program parameters.

Localized States of a Binary Alloy

Abstract: The localization phenomena exhibited by a commonly studied model of electrons in a substitutional alloy are found to be much richer than has previously been reported. A nondegenerate tight-binding band arising primarily from one constituent of the alloy is considered. It may possess states localized in small isolated clusters (as studied in percolation theory), and localized states decaying exponentially at large distances (as in the Anderson model), plus a third class of localized states which have not been discussed before. These last states occur at special energies, but are not isolated from the bulk of the material. Examples are constructed, and an approximate calculation of their spectral weight is carried out. This enumeration provides an explanation of the anomalies which have appeared in recent numerical calculations of the density of states of this model. The continuous part of the spectrum also displays surprising behavior, as revealed by numerical calculations. There appears to be a "forbidden energy" at the center of the band, at which the density of states goes continuously to zero. The eigenstates at nearby energies appear to be localized in the Anderson sense. The model exhibits not one, but several pairs of mobility edges, separating localized from extended states. These calculations make available nontrivial exact results for a three-dimensional disordered material, as a test of approximate theories. None of the existing theories predict these effects. In addition, we suggest several real systems in which the new class of localized states, and perhaps the associated effects on the continuous spectrum, can be observed.

Photoemission Densities of Intrinsic Surface States for Si, Ge, and GaAs

Abstract: Photoemission-energy-distribution measurements of intrinsic surface states for Si, Ge, and GaAs have been made using synchrotron radiation in the 7-25-eV range. Occupied intrinsic surface states with Gaussian-shaped optical densities of states about 0.8 to 1.0 eV wide, centered at 0.75, 0.7, and 1.05 eV below the Fermi level, are observed for Si, Ge, and GaAs, respectively. These bands are centered at about 0.45, 0.75, and 0.5 eV below the valence-band edge ${E}_{v}$, respectively, rather than at or above ${E}_{v}$ as has been generally concluded.

On the Measurement of Indices of Refraction of Nematic Liquids

Abstract: We wish to report on a simple method for measuring the birefringence and indices of refraction of nematic liquids with an accuracy comparable with or superior to previously reported means.(1–3) The method is exemplified in measurement of the temperature dependences of the indices of refraction of p-methoxybenzylidene p-butylaniline (MBBA) at two wavelengths.

Method of aligning and attaching circuit devices on a substrate

Abstract: Method for aligning and supporting micro-circuit devices on substrate conductors during attachment thereto in which shaped, flexible, insulative material is placed between the devices and their respective conductors to support heat fusible terminals of the devices in alignment with mating heat-fusible conductor lands during formation of the respective fused connections. The insulative material can be of selected thickness to support the non-attached terminals either in contact or out of contact with their mating lands. When the circuit devices are held out of contact with their lands, the supporting material, being of plastic character, softens during heating to allow contact during the joining of the fusible connections and, upon cooling, returns to a thicker state to elongate the fused connections.