Showing papers by "Philips published in 1982"

Diffuse Ferroelectric Phase Transitions in Ba(Ti1-yZry)O3 Ceramics

Abstract: Very high and broad Curie maxima are observed in ceramic Ba(Ti1-yZry)O3 mixed crystals, which are often used for the preparation of ceramic dielectrics The ferroelectric-to-paraelectric phase transition of ceramic Ba(Ti1-yZry)O3 was studied using dielectric measurements, quantitative DTA, X-ray diffraction, and determination of the remanent polarization At higher Zr concentrations, it was found that ferroelectric and paraelectric phases coexist in a wide temperature region Up toy =016, the phase transition remains first order The diffuse character is promoted by the small energy difference between the ferroelectric and paraelectric phases appearing at higher Zr content It can be best described by a normal distribution of Curie temperatures using the phenome-nological theory of Devonshire and the Newton-Raphson mathematical approximation

Electrical properties and defect model of tin-doped indium oxide layers

Abstract: Tin-doped In2O3 layers were prepared by the spray technique with doping concentrationsc Sn between 1 and 20 at. % and annealed at 500 °C in gas atmospheres of varying oxygen partial pressures. The room-temperature electrical properties were measured. Maximum carrier concentrationsN=1.5×1021cm−3 and minimum resistivities ϱ=1.3×10−4 Ω cm are obtained if the layers are doped withc Sn≈9 at. % and annealed in an atmosphere of oxygen partial pressurep O2 ⋦10−20 bar. At fixed doping concentration, the carrier mobility increases with decreasing oxygen pressure. The maximum obtainable mobility can be described in terms of electron scattering by ionized impurities. From an analysis of the carrier concentration and additional precision measurements of the lattice constants and film thicknesses, a defect model for In2O3:Sn is developed. This comprises two kinds of interstitial oxygen, one of which is loosely bound to tin, the other forming a strongly bound Sn2O4 complex. At low doping concentrationc Sn≲4 at. % the carrier concentration is governed by the loosely bound tin-oxygen defects which decompose if the oxygen partial pressure is low. The carrier concentration follows from a relationN=K 1 ·p O2 −1/8 ·(3 ×1010 × cSn −N)1/4 with an equilibrium constantK 1=1.4×1015 cm−9/4bar1/8, determined from our measurements.

Fast decipherment algorithm for RSA public-key cryptosystem

Abstract: A fast algorithm is presented for deciphering cryptograms involved in the public-key cryptosystem proposed by Rivest, Shamir and Adleman. The deciphering method is based on the Chinese remainder theorem and on improved modular multiplication algorithms.

Improving the linearity of piezoelectric ceramic actuators

Abstract: It is shown that the linearity of a piezoelectric ceramic actuator may be greatly improved if the applied electric charge, rather than the applied voltage, is varied to control the extension. Hysteresis is virtually eliminated.

Method of manufacturing fluorine-doped optical fibers

Abstract: Doped silica glass can be manufactured by reacting gaseous vapors of silica-forming compounds and dopant-forming compounds. Increased fluorine dopant can be provided with less fluorine dopant-forming compound, when the fluorine dopant-forming compound is hexafluoroethane (C 2 F 6 ).

Bi-axial supporting arrangement which can withstand high acceleration forces

Abstract: The invention relates to a bi-axial support of a rotatable body in a projectile for supporting said body such that it can perform small tilting motions about two mutually perpendicular axes lying in a plane, which is perpendicular to the longitudinal axis of the projectile. The support consists of a spherical or partly spherical bearing body introduced into a correspondingly spherical cup-shaped recess in a projectile-fixed part having the open end directed forwards in the motion direction of the projectile. The spherical bearing body is retained in the recess by means of two pairs of link arms defining two virtual tilting axes for the bearing body and connected to two output shafts such that a tilting motion of the body about the respective virtual axis results in a rotation of the respective output shaft and vice versa. When firing the projectile the spherical surface of the bearing body comes in metallic contact with the spherical surface of the recess, whereby the support can withstand very high acceleration forces in any direction.

Determination of the optical bandgap of amorphous silicon

Abstract: The optical bandgap of glow-discharge and sputter-deposited a-Si has been deduced from measurements of the absorption coefficient α using a linear extrapolation of (αhvn)1/3 as a function of the photon energy h v. The exponent 1/3 is used instead of 1/2, resulting in a much better fit to the data. The influence of the method of extrapolation on the resulting value for the optical bandgap has been assessed.

On stationary linear time-varying systems

Abstract: A comprehensive review of representations of linear timevarying systems is given, both in the time and in frequency domains. Subsequently a definition is given of a stationary deterministic signal. Based on this definition the notion of stationary systems is introduced. These systems have the useful property that the spectral relation between input and output has a simpler form than the corresponding relation for arbitrary time-varying systems. It is shown that causality puts rather severe constraints on the frequency mappings that can be realized by stationary linear systems. An extension of the theory of linear time-varying systems to the case of discrete-time and hybrid systems (analog input, digital output, or vice versa) is discussed. Examples of stationary systems are given, such as a decimator, a periodic sampler, and a bilinear A/D converter. Also, a recently proposed generalized sampling method is analyzed by means of the concepts discussed in this paper.

Surface electronic structure of GaAs(001)-(2×4): Angle-resolved photoemission and tight-binding calculations

Abstract: We have carried out an experimental and theoretical study of the surface-energy-band structure of the As-stable GaAs(001)-(2\ifmmode\times\else\texttimes\fi{}4) reconstruction. Angle-resolved photoemission measurements with the use of synchrotron radiation at LURE, Orsay, have been performed on surfaces which were grown in situ by molecular beam epitaxy. Measurements made at high-symmetry points and along symmetry lines of the surface Brillouin zone show weakly dispersing dangling-bond-like surface states in the energy range between - 1.6 eV and the top of the valence band, and a nearly dispersionless state near - 3 eV. To clarify the origin of these states, we have applied the scattering theoretical method on the basis of an empirical tight-binding description of the GaAs bulk crystal to the ideal (1\ifmmode\times\else\texttimes\fi{}1) As-terminated surface and to a (2\ifmmode\times\else\texttimes\fi{}1) asymmetric As-As dimer model. The principal effect of the reconstruction is the introduction of a new dimer-related state at - 3.5 eV. In addition in the energy range near the top of the projected bulk bands, dangling-bond states with a significant in-plane component are found. Although we do not observe a direct one-to-one correspondence between experiment and theory, the essential features of an asymmetric As-As dimer are established.

Grain boundary states and the characteristics of lateral polysilicon diodes

Abstract: In lateral n+p−p+ diodes made in LPCVD polycrystalline silicon films, the energy distribution of the traps at the grain boundaries is found to be U shaped. They have a density of about 1012 cm−2 and a capture cross section of about 10−16 cm2. The forward current of the diodes is ascribed to recombination, the reverse current to field-enhanced generation via these traps.

Electrophoretic image display with reduced drives and leads

Abstract: An electrophoretic display device is described where a set of anode electrodes in an electrophoretic cell are disposed opposite row and column electrodes at a second side of the electrophoretic cell. The anode electrodes encompass equal pluralities of at least the row electrodes, and such equal pluralities of electrodes are connected in parallel. This significantly reduces the number of leads to the display.

Display system with nested information display

Abstract: An information display system which can produce an information display (e.g. on a television monitor) from any one of a plurality of different information sources. The information sources are associated with different facilities such as teletext and viewdata. In order to obtain information from a particular information source, the associated facility option is selected from the available facility options by selecting from the television screen "nested" areas which pertain to one or more facility options. The selection can be effected using a touch-sensitive screen which overlies the television screen. The selection process may comprise the display of a number of successive display frames containing "nested" areas. The selection of an area in one frame produces a fresh display frame which redefines areas which are nested within the selected area.

Contour recording device

Abstract: A device for measuring object contours (11) comprises a mirror system with at least three mirrors (13) for reading a contour marked preferably by means of several light sources (12). The contour detection system comprises lenses (14) which render the measurement angle-independent and a collecting optical system (15). The collecting optica) system (15) forms a single faithful image from the sub-images from the respective mirrors (13), which is then imaged, for example, on a television camera (17). The device furthermore comprises an image display device (21) and means (24) for the comparison of contours.

Binary phase gratings for star couplers with high splitting ratio

Abstract: Binary phase transmission gratings exhibiting a certain number N of central diffraction orders of equal intensity can be used to construct star couplers of the 1-to-N and N-to-N type. The calculation of the grating's groove structure is described, and first experimental results are presented.

Atomic resonance line source lamps and spectrophotometers for use with such lamps

Abstract: The present invention is directed to a lamp assembly for use in atomic absorption spectrometers in which an atomic element hollow cathode lamp assembly has a lamp formed by a hollow cathode electrode and an anode electrode within a sealed envelope A base structure is attached to the envelope, and located within the base structure is a resistor network consisting of four resistors connected to a common lead and having four plug terminals protruding from the base structure Two further plug terminals also protruding from the base structure are connected respectively to the cathode and anode electrodes to provide a connecting structure for connecting these electrodes to a lamp power supply The five plug terminals protruding from the base structure and connected respectively to the resistors and the common lead provide a further connecting structure of the resistor network to a measurement circuit in an atomic absorption spectrophotometer The resistor network represents the atomic element of the lamp by virtue of two of the resistors, and further, represents a lamp operating current by virtue of the other two resistors All of the plug terminals are arranged in a conventional octal plug configuration with a boss on the base structure for insuring correct electrical connection

Homogeneous distribution of frequencies in a regular hexagonal cell system

Abstract: A theory of optimal adjacent channel distance in homogeneous hexagonal cell systems is developed. Algorithms generating frequency distributions with best adjacent channel distance, valid for arbitrary co-channel reuse ratios, are presented. The theory may be applied to mobile radio telephone systems or broadcast services.

Coaxial cable with a connector

Abstract: Coaxial cable (1) with a connector which comprises a central contact (23) connected to the central conductor (3) and a sheath contact (11) connected to the conducting sheath (7) An end portion of the conducting sheath is axially flattened to form a disk and is clamped between a transverse wall (15) of the sheath contact (11), which wall is provided at the center with a passage (17), and a sleeve (19) which is bent inwards at its edge and is arranged coaxially with the transverse wall As a result, the operation of mounting the connector can be mechanized very simply and readily

Enthalpy Effects in Amorphous Alloys and Intermetallic Compounds in the System ZrCu

Abstract: The enthalpies of formation are measured in the intermetallic compounds Zr2Cu, ZrCu and the amorphous alloy Zr0.55Cu0.45 by means of a solution calorimeter based on liquid aluminium. The crystallization enthalpies of the amorphous alloys Zr1 —xCux with x = 0.38, 0.45, and 0.55 are determined by means of a differential scanning calorimeter. All these values are found to be relatively small compared with the activation energies for crystallization derived from a study of the crystallization temperature as a function of the heating rate. The enthalpy difference between amorphous and crystalline materials is analysed in terms of Miedema's model. The results indicate that the lower enthalpy content in the former materials is mainly due to a less effective surrounding of the atoms by dissimilar atoms. Die Bildungsenthalpien der intermetallischen Verbindungen Zr2Cu, ZrCu und der amorphen Legierung Zr0,55Cu0,45 werden mit einem Losungskalorimeter auf der Basis von flussigem Aluminium gemessen. Die Kristallisationsenthalpien der amorphen Legierungen Zr1 —xCux mit x = 0,38; 0,45; und 0,55 werden mit einem Differential-Abtast-Kalorimeter bestimmt. Es wird gefunden, das alle Werte relativ klein sind im Vergleich zu Aktivierungsenergien aus einer Untersuchung der Kristallisationstemperatur in Abhangigkeit von der Aufheizgeschwindigkeit. Der Enthalpieunterschied zwischen amorphen und kristallinen Materialien wird mit dem Modell von Miedema analysiert. Die Ergebnisse zeigen, das die niedrigere Enthalpie des ersteren Materials hauptsachlich durch eine weniger effektive Umgebung der Atome durch unahnliche Atome verursacht wird.

Method of providing raised electrical contacts on electronic microcircuits

Abstract: A method of providing a raised contact portion on a contact area of an electronic microcircuit in which a ball is formed at one end of a metal wire by means of thermal energy, the ball is pressed against a contact area of the electronic microcircuit and is connected to said contact area. A weakening is created in the wire near the ball and the wire is then severed at the area of the weakening to provide the desired raised contact portion.

A picture display arrangement

Abstract: An arrangement for the display of individually selectable map background pictures combined with an overlay of selectable predefined or operator generated symbols. The arrangement comprises a video disc player with a video disc carrying the map pictures and a computer in which symbol generative data of the predefined symbols are stored. A picture generator transforms the symbol generated data into a video signal and a video mixer combines the video signals of a map picture and symbol generative data such that the symbol picture non-transparently covers the map picture. The combined signal is displayed on a color monitor. The video disc allows for rapid access to a large number of maps and the generation of the overlay information requires only a limited computer capacity. The arrangement is specifically useful for rapid and flexible indications of military operations.

Modular data storage system

Abstract: A modular data storage system for a plurality of identical data carriers (3) includes at least one recorder apparatus and at least one storage module (10). The storage module includes an internal transport device (32). An external transport device (13) is associated with the outside of the storage module, which external transport device can transport data carriers between the recorder apparatus and the storage module. The recorder apparatus includes a recorder module (9) comprising a module frame having outer dimensions which are substantially equal to those of a module frame of the storage module so that all of these modules can be arranged successively adjacent to form optional configurations adapted to suit specific requirements. The external transport device (13) cooperates with the recorder and storage modules at their backs and is located inside a cabinet (5, 6, 8, 13) of the modular data storage system.

Algebraic constructions of Shannon codes for regular channels

Abstract: The problem of the explicit construction of encoders achieving Shannon's capacity and admitting a simple decoding algorithm is considered. A solution based on Justesen's idea of variable concatenated codes is given for the case of a symmetric memoryless channel with an input alphabet of prime power order, under the assumption that the information messages are equiprobable. This construction remains good for a nonsymmetric channel provided the encoding rate is smaller than a well-defined "pseudocapacity." In case the channel is regular, it is shown that the error probability after decoding is an exponentially decreasing function of the block length for any encoding rate less than the channel capacity.