Showing papers by "IBM published in 1971"

Liquid argon: Monte carlo and molecular dynamics calculations

Abstract: Thermodynamic properties of liquid argon are calculated by Monte Carlo and molecular dynamics techniques, using accurate pair-potential functions determined from the properties of solid and gaseous argon, together with the Axilrod-Teller three-body interaction. Satisfactory techniques for evaluating three-body contributions to thermodynamic properties without excessive requirements of computer time are described. Quantum corrections are included. Agreement with experiment is excellent: the best pair and triplet potentials give an excellent description of the properties of solid, gaseous and liquid argon.

A data base sublanguage founded on the relational calculus

Abstract: Three principal types of language for data base manipulation are identified: the low-level, procedure-oriented (typified by the CODASYL-proposed DML), the intermediate level, algebraic (typified by the Project MAC MacAIMS language), and the high level, relational calculus-based data sublanguage, an example of which is described in this paper. The language description is informal and stresses concepts and principles. Following this, arguments are presented for the superiority of the calculus-based type of data base sub-language over the algebraic, and for the algebraic over the low-level procedural. These arguments are particularly relevant to the questions of inter-system compatibility and standardization.

An Automated Technique for Obtaining Cloud Motion from Geosynchronous Satellite Data Using Cross Correlation

Abstract: An automated procedure has been developed for determining cloud motion from geosynchronous satellite pictures based on the use of cross correlation. The speed required for use in a real-time operational system is attained by application of the fast Fourier Transform as a computation algorithm in determining the cross-correlation coefficients. The input data consists of a pair of pictures from the Applications Technology Satellite ATS-I taken 24 main apart and mapped on a Mercator projection. Relative mapping errors are automatically corrected by matching common landmarks on the two pictures. A sample of 300 vectors determined from low-level clouds was compared with those obtained by manual methods in a non-operational environment. Speeds agreed within 10 kt in 82% of the cases and directions within 30° in 72% of the sample. Comparisons of 300 vectors with those obtained from a manual operational procedure showed similar results for direction but indicated that the automated procedure was better a...

Long wavelength optical phonons in mixed crystals

Abstract: Experimental data on optical phonons in mixed crystal systems obtained by infra-red, Raman, and other optical measurements are reviewed. In terms of their spectral behaviour, mixed crystals may be classified into different types, using as criteria the mass ratios of the constituent atoms and the inter-atomic forces. Several phenomenological models have so far been proposed for the explanation of the mixed crystal behaviour; these are reviewed. The difficulties facing a realistic and thorough lattice dynamical calculation of a disordered system are pointed out. Further experimental work needed for confirming and gaining understanding of the true behaviour types of some mixed crystal systems is suggested.

Raman Spectra of Amorphous Si and Related Tetrahedrally Bonded Semiconductors

Abstract: Raman scattering has been studied in the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb). All vibrational modes of the material can take part in the scattering process, and the Raman spectrum is a measure of the density of vibrational states. The amorphous phases are found to have vibrational spectra very similar to the corresponding crystals, reflecting the similarity in short-range order of the two phases.

The Sparse Tableau Approach to Network Analysis and Design

Abstract: The tableau approach to automated network design optimization via implicit, variable order, variable time-step integration, and adjoint sensitivity computation is described. In this approach, the only matrix operation required is that of repeatedly solving linear algebraic equations of fixed sparsity structure. Required partial derivatives and numerical integration is done at the branch level leading to a simple input language, complete generality and maximum sparsity of the characteristic coefficient matrix. The bulk of computation and program complexity is thus located in the sparse matrix routines; described herein are the routines OPTORD and 1-2-3 GNSO. These routines account for variability type of the matrix elements in producing a machine code for solution of Ax=b in nested iterations for which a weighted sum of total operations count and round-off error incurred in the optimization is minimized.

Experiments in mixed-integer linear programming

Abstract: This paper presents a “branch and bound” method for solving mixed integer linear programming problems. After briefly discussing the bases of the method, new concepts called pseudo-costs and estimations are introduced. Then, the heuristic rules for generating the tree, which are the main features of the method, are presented. Numerous parameters allow the user for adjusting the search strategy to a given problem.

Static Critical Exponents at Structural Phase Transitions

Abstract: The temperature dependence of the rotational displacement parameters below the second-order phase transitions in SrTi${\mathrm{O}}_{3}$ and LaAl${\mathrm{O}}_{3}$ at ${T}_{a}=105.5 \mathrm{and} 797$\ifmmode^\circ\else\textdegree\fi{}K is described by an exponent $\ensuremath{\beta}=0.33\ifmmode\pm\else\textpm\fi{}0.02$ down to $t=\frac{T}{{T}_{a}}=0.95$. For smaller $t$'s there occurs a change to Landau behavior approximately followed between $t=0.9 \mathrm{and} 0.7$. The observation of static critical exponents near displacive phase transitions confirms now the notion of universality in this field.

Centralized verification system

Abstract: This specification describes a multi-terminal data processing system having means and process for verifying the identity of subscribers to the system. Validity of a terminal request for communication with the data processing system are determined on the basis of a centralized verification system. Each subscriber to the system is identified by a unique key binary symbol pattern. The central data processing unit contains a listing of all valid keys for subscribers to the system. Two embodiments of the centralized verification system are presented, a password system and a handshaking system. In the password system, all data or information originating at the terminal under use of the subscriber is enciphered in combination with the unique subscriber key. Upon proper deciphering of the key or password at the central processing unit and arriving at a match with one of the keys in the processor''s listing, the subscriber may communicate with the processing system. In the handshaking system embodiment, the user and the central processor exchange a plurality of messages each formed by a combination of new and prior received data. Received data messages are also maintained within the registers at both the terminal and the central processor for further verification upon the return of the portion of the message that was previously transmitted.

Photo Echo and Optical Nutation in Molecules

Abstract: Photon echo and optical nutation have been easily observed in ${\mathrm{C}}^{13}$${\mathrm{H}}_{3}$F and N${\mathrm{H}}_{2}$D by applying Stark pulses which shift the molecular levels into resonance with cw laser radiation. Numerical computations of the nutation effect agree with observation, and echo characteristics closely follow predictions of existing theories. The $T_{2}^{}{}_{}{}^{\ensuremath{'}}$ pressure dependence, from infrared-echo measurements, indicates that ${\mathrm{C}}^{13}$${\mathrm{H}}_{3}$F relaxes primarily by rotational energy transfer.

Photoemission Studies of Energy Levels in the Palladium-Hydrogen System

Abstract: Photoemission studies of the Pd/H system show a band of hydrogen-induced energy states centered at 1 eV below the bottom of Pd-derived d bands of width 4.4 eV. These results show that the widely accepted simple "proton model" of Pd/H is misleading. Our augmented-plane-wave calculations of PdH, ${\mathrm{Pd}}_{4}$${\mathrm{H}}_{3}$, and ${\mathrm{Pd}}_{4}$H exhibit these lowlying states and also explain why the added number of electrons (0.6) in $\ensuremath{\beta}$-phase PdH exceeds the number of $d$-band holes (0.36) in Pd.

Allocation of copies of a file in an information network

Abstract: We consider a mathematical model of an information network of n nodes, some of which contain copies of a given data file. Within this network, every node is able to communicate with every other node over communication links (a process which may entail routing through intermediate nodes). In particular, we are concerned with transactions with the multiply-located file. Such transactions fall into one of two classes: (1) query traffic between a node and the file, and (2) update traffic. An update message is assumed to be transmitted to every copy of the file, whereas a query is communicated only to a single copy.

Photoemission Measurements of the Valence Levels of Amorphous Si O 2

Abstract: The complete valence band in amorphous Si${\mathrm{O}}_{2}$ has been examined by photoelectron spectroscopy at photon energies of 21.2, 26.9, 40.8, and 1486.6 eV. The spectra show emission from an 11.2-eV-wide $p$-derived valence band and from the oxygen $2s$ level at 20.2 eV below the valence-band edge. Four pieces of structure in the $p$ bands are related to the single bonding and the two nonbonding orbitals of the ${\mathrm{O}}^{\ensuremath{-}\ensuremath{-}}$ ion. A narrow, nonbonding level found at the valence-band edge may cause lattice trapping of valence-band holes.

Digital filter for pcm encoded signals

Abstract: A digital filter either of a recursive or transversal type responsive to successive digitally encoded analog signal samples of m bits each. The filter comprises an accumulator for multiplying and summing a weighted hybrid value obtained from a memory medium addressed by a selected one of the m bits of each of N digitally encoded signal samples. If the bits of the N samples used for addressing the memory are derived from successive input signals only, then the filter is of the transversal type. If V of the N signals whose bits are used for addressing are from the input samples and R of the N signals whose bits also are used for addressing are obtained from filter output signals, then the filter is recursive. By addressing the memory with the binary value of like bit positions of the signal samples, then a hybrid value may be stored, which hybrid value need only be multiplied and combined by the accumulator. This permits the use of a substantially smaller memory than that required if the digits of the signals looked up the completed weighted function.

Normalized data base structure: a brief tutorial

Abstract: Casual and other users of large formatted data bases need a simple tabular (relational) view of the data rather than a network or tree-structured view. This paper illustrates the removal of repeating groups, hierarchic and plex structures, and cross-referencing structures. Finally, the simplification of data base relations by normalization is discussed.

Data base task group report to the CODASYL programming language committee, April 1971

Abstract: It is the pleasure of the Conference on Data Systems Languages (CODASYL) to submit a second report of the Data Base Task Group (DBTG) for general distribution. This report reflects many of the changes, improvements and extensions suggested as a result of publication of the first report. It also reflects the request of the CODASYL Executive Committee that the specifications be separated into two categories, namely 1) those elements that would be necessary for an independent data description language and 2) those elements that would enable COBOL to interface properly with data described in that independent data description language. With this report as the base, CODASYL has now established a new standing committee, the Data Description Language Committee, independent of and equal to the Planning, Systems and Programming Language Committees. It is envisioned that from the base already established by the DBTG report this new committee will finalize the specifications for a common data description language, independent of but common to many other higher level programming languages. Simultaneously, the Programming Language Committee will develop COBOL extensions based on Section 4 (COBOL Sub-schema) and Section 5 (COBOL Data Manipulation Language). It is hoped that organizations responsible for other programming languages will develop the appropriate sub-schema and data manipulation language features for their language. While this report is not classified as a final CODASYL specification of a common language, it does represent many years of work and the best thinking of many recognized experts. Therefore we believe it is practical and appropriate for implementations to be made based on these specifications so that a foundation of experience may be established from which to further evolve and refine the specifications of a common data description language.

A new high-sensitivity organic photoconductor for electrophotography

Abstract: A new organic photoconductor has been developed, consisting essentially of a 1:1 molar ratio of one molecule of 2, 4, 7- trinitro-9-fluorenone (TNF) to one monomer unit of poly-N-vinylcarbazole (PVCz). This photoconductor (1:l TPC) is nearly panchromatic int he visible range of the spectrum and has white-light sensitivity approximately equal to that of amorphous selenium when used for electrostatic imaging. The photosensitivity, which is due mainly to the TNF-PVCz complex, is greater for negative corona charging than for positive charging. Charge acceptance of the 1:1 TPC is high, ≅ 1200 volts for a 13µm film, indicating good dielectric strength. Dark decay of the charge is affected by substrate materials and substrate surface conditions. In general dark decay is slower for negative charging than for positive charging. Quantum efficiency (Q. E.) is nominally about 0.15 in the range of 400 to 500 nm but decreases somewhat for shorter and longer wavelengths. The Q.E. increases rather markedly with field strength, but decreases somewhat at high light intensities. Field-controlled photogeneration of carriers is indicated, and thermal measurements show a field-dependent activation energy in the range of 0.06 to 0.20 eV. The absence of residual potentials in light decay curves and the lack of a thickness effect in photodischarge currents indicate that no deep traps are present in the 1:1 TPC layers.

Electromigration and failure in electronics: An introduction

Abstract: Some fundamental aspects of electromigration phenomena as they have been studied in "bulk" metallic conductors are reviewed. In an electric field atoms are subjected to a force due to the field, and to a force which results from the motion of electrical carriers, electrons, or holes. In bulk samples, and at high temperatures, these forces cause the displacement of atoms by a lattice mechanism which is also responsible for the diffusion of atoms in a concentration gradient. In thin films, electromigration has been found to occur at lower temperatures (and higher current densities) by a grain boundary diffusion mechanism. Electromigration may cause failures at material discontinuities, such as found at terminals, at temperature gradients, or at structural inhomogeneities. The process of crack formation, as observed in aluminum thin films, is described. Failure times are a function of the activation energy for diffusion and of exponents of the current density which vary for different failure modes. The effects of film purity, orientation, grain size, glass overcoat, and solute additions on lifetime are reviewed. Practical guidelines for the design of thin-film interconnections, and for the interpretation of accelerated test data are given.

Correlative level coding and maximum-likelihood decoding

Abstract: Modems for digital communication often adopt the so-called correlative level coding or the partial-response signaling, which attains a desired spectral shaping by introducing controlled intersymbol interference terms. In this paper, a correlative level encoder is treated as a linear finite-state machine and an application of the maximum-likelihood decoding (MLD) algorithm, which was originally proposed by Viterbi in decoding convolutional codes, is discussed. Asymptotic expressions for the probability of decoding error are obtained for a class of correlative level coding systems, and the results are confirmed by computer simulations. It is shown that a substantial performance gain is attainable by this probabilistic decoding method.

Phase-Only Complex-Valued Spatial Filter*

Abstract: A new type of phase-only filter is described for wave-front construction, in which both the amplitude and phase information necessary to construct an arbitrary image over a limited field are encoded. It is shown that this phase-only filter can duplicate the performance of an ideal complex-valued spatial filter (a filter that controls both amplitude and phase transmittance). This phase-only filter controls the amplitude transmittance by the use of a modulated high-frequency phase carrier that diffracts a controlled amount of light into the image. This type of filter is particularly useful in the implementation of computational wave-front construction, because the maximum spatial frequency that must be plotted is associated with the image and not the carrier. The performance of the filter is examined both numerically and experimentally.

Block cipher cryptographic system

Abstract: A cryptographic system for encrypting a block of binary data under the control of a key consisting of a set of binary symbols. The cryptographic system is utilized within a data processing environment to ensure complete privacy of data and information that is stored or processed within a computing system. All authorized subscribers who are permitted access to data within the network are assigned a unique key consisting of a combination of binary symbols. The central processing unit within the computing network contains a complete listing of all distributed authorized subscriber keys. All communications transmitted from terminal input are encrypted into a block cipher by use of the cryptographic system operating under the control of the subscriber key which is inputed to the terminal device. At the receiving station or central processing unit, an identical subscriber key which is obtained from internal tables stored within the computing system is used to decipher all received ciphered communications. The cryptographic system develops a product cipher which is a combination of linear and nonlinear transformations of the clear message, the transformation being a function of the binary values that appear in the subscriber key. In addition to the transformation, the key controls various register substitutions and modulo-2 additions of partially ciphered data within the cryptographic system.