Showing papers by "General Electric published in 1973"

Optical Properties of Silicon Nitride

Abstract: The optical properties of silicon nitride layers formed by the pyrolysis of a mixture of and are presented. These results are used together with published data for materials to formulate a bonding model for and which quantitatively describes their optical characteristics. The basic units of this structure are Si tetrahedra of the type in which the distribution of atoms for all possible is statistical for any given atom ratio.

Flame retardant polycarbonate composition

Abstract: A flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic sulfonic acids, or mixtures thereof.

Some Remarks on the Polymorphism of Smectics

Abstract: We discuss the nature of the order in the main smectic phases (A, C, and B) together with the related phase transitions. (1) The B phase may correspond to a plastic crystal, or to a system of weakly coupled solid layers: to discriminate between these two models, acoustical studies using shear waves appear to be most promising, (2) the transitions A  N, C  N, C  A (where N stands for nematic) may be of second order in certain cases, which will allow for a number of interesting experiments. The C  A transition should be very similar to the λ transition of helium, and some critical exponents which are not accessible in helium could be measured here. The N  A transition is similar to the onset of superconductivity in a metal. A bend (or twist) deformation tends to suppress the A phase just as a magnetic field destroys superconductivity. In the N phase the twist and bend elastic constants should show pretransitional anomalies. The C  N transition is more complex. A tentative calculation suggests...

High-Permittivity Temperature-Stable Ceramic Dielectrics with Low Microwave Loss

Abstract: The compounds SrZrO3 and CaZrO3 combine high permittivity with low loss and positive temperature coefficient of permittivity. Temperature-stable materials were produced by forming solid solutions between these zirconates and zirconates or titanates having negative coefficients. The properties of temperature-stable compositions in the systems Ca(Zr,Ti)O3 and (Ba,Sr)(Zr,Ti)O3 were investigated. At 4 GHz the relative permittivities were from 29 to 35 and the loss tangents from 3 to 11×10−4. Both permittivity and microwave loss increased as the principal alkaline-earth ion was changed from Ca to Sr to Ba, but the higher losses could be reduced by adding ∼1 mol% Nb or Ta. Dense fine-grained ceramics with the properties required for microwave applications were prepared.

Method for making polyetherimides

Abstract: A process for making polyetherimides is provided by melt polymerizing a mixture of organic diamines and certain aromatic bis(etherdicarbonyl) compounds such as aromatic tetra-carboxylic acids and dianhydrides thereof. The polyetherimides can be made in a continuous manner. Fillers can be incorporated into the polyetherimides to produce high performance composites.

Polycrystalline ceramic lasers

Abstract: A method of making a laser body from a high density yttria-based ceramic material is provided. The method involves forming an aqueous solution containing water soluble salts of yttrium, thorium and neodymium, coprecipitating the cations from solution with oxalic acid, recovering the oxalate precipitate in the form of a purified dried powder, calcining the powder to convert the oxalates to the oxides, particulating the oxides in a rubber-lined ball mill, pressing the powdered oxides into a "green body", sintering the "green body" in a hydrogen atmosphere and rapidly cooling the sintered body to form an improved lasing ceramic material.

Efficient Mn(IV) Emission in Fluorine Coordination

Abstract: The efficiency of Mn(IV) luminescence in fluorine coordination is discussed in the context of the chemical bonding in the center. It is possible that the lower degree of σ‐antibonding in the orbitals, and the greater degree of π‐antibonding in the orbitals, compared with the effect observed in oxides, contributes to a high efficiency and quenching temperature of the emission. The excitation and emission spectra of Mn(IV) in , , and are presented and compared.

Calculation of Modulation Transfer Functions of X-Ray Fluorescent Screens

Abstract: Formulas have been derived for calculating the modulation transfer function of x-ray intensifying screens. Emphasis has been placed on simplified models where results can be obtained in closed form and a physical understanding more easily realized. For selected cases, the MTF’s of transparent screens are calculated by direct integration. The MTF’s of diffusing screens are determined from suitable approximate solutions of the Boltzmann equation. The intermediate case and the transition from scattering to nonscattering are discussed. As a byproduct, formulas for light output and signal-to-noise ratio are obtained.

Boron, the Dominant Acceptor in Semiconducting Diamond

Abstract: A study has been made to determine the nature of the acceptor center in laboratory-grown semiconducting diamonds. Analyses for nitrogen, aluminum, boron, and uncompensated-acceptor content of aluminum and boron-doped crystals have shown that (i) the aluminum content of inclusion-free crystals is very low, (ii) there is not enough aluminum to account for the acceptor content, (iii) the nitrogen content is very low and only a small degree of compensation by deep-lying nitrogen donors could exist for many semiconducting diamonds, and (iv) there is a good correlation between boron content and acceptor content. These results indicate that boron is the dominant acceptor in laboratory-grown semiconducting diamond, and not aluminum as has been assumed previously by a number of authors. These results, when combined with other data on resistivity and activation energy for conduction, indicate that the dominant semiconducting properties of both natural and laboratory-grown diamond are due to one acceptor, boron, at different concentrations. Previous papers on laboratory-grown semiconducting diamonds which based arguments on the large aluminum content and the assumed high nitrogen content are critically reexamined.

A Woman's Place: A Follow-Up Analysis of the Roles Portrayed by Women in Magazine Advertisements:

Abstract: In the February 1971 issue of the Journal of Marketing Research, Alice E. Courtney and Sarah W. Lockeretz analyzed the roles portrayed by women in magazine advertisements in general interest publications [2]. Their study led them to conclude that advertisements appearing in April 1970 issues of 7 general publications did not present a full view of the variety of roles women actually play in American society. This article determines whether, during a time interval of 20 months, advertisers have responded to many critics who have claimed that too many advertisements have overemphasized the role of women as mere housewives in our society. A follow-up study was undertaken by examining advertisements appearing in the January 1972 issues of 7 general magazines-Life, Newsweek, The New Yorker, Saturday Review, Time, U.S. News and World Report, Reader's Digest, and New York Times Magazine Section. The first 6 general magazines examined were identical with those used in the original study. Since Look suspended publication, the only change in publications examined was the substitution of the January 2 issue of New York Times Magazine Section for Look. The same occupational and nonoccupational classifications of women were also used in the follow-up study. As in the original study, advertisements evaluated contained one or more adults.

Method for making polyetherimide

Abstract: A method is provided for making polyetherimide from certain bis(nitrophthalimide) and alkali diphenoxides. Higher polyetherimide intrinsic viscosity is achieved if the alkali diphenoxide is employed as a preformed substantially anhydrous reaction product of a diphenoxide and a sodium alkoxide in a C(13) alkanol.

Method for making polyetherimides

Abstract: A method is provided for making polyetherimides having improved heat stability involving the initial production of a polyetherimide by the nitro-displacement of dinitro-bisimide with alkali diphenoxide and the employment with the resulting polyetherimide of an alkali metal phenoxide stabilizer.

The C-V characteristics of Schottky barriers on laboratory grown semiconducting diamonds

Abstract: Measurements of the differential capacitance of evaporated gold Schottky barriers on laboratory-grown, boron-doped semiconducting diamonds have been obtained for the first time as functions of reverse-bias voltage, frequency, and temperature The data are analyzed on the basis of a model which includes the effects of long time constants for hole capture from the deep (boron) level, as well as previously unobserved effects due to the series resistance of the bulk The barrier height at 300°K is found to be 1·73 ± 1·10 eV , in good agreement with the ‘one-third band gap’ value of Mead and Spitzer Excellent correlation is found between optical transmission measurements and the C-V analysis for the uncompensated boron concentration, indicating that all of the optically observable dopant is electrically active By fitting the model with two adjustable parameters at room temperature, good agreement is obtained between measured and calculated capacitance over two and a half decades as a function of temperature The analysis indicates that the activation energy of the acceptor level is 0·26–0·37 eV for the samples studied, while the associated capture cross-sections are 0·9–2·0 × 10 −17 cm 2

Solar-Induced-Currents in Power Systems: Cause and Effects

Abstract: This paper summarizes a research effort investigating the effects of geomagnetic storms on electric power systems. Geomagnetic storms, which are caused by solar flares, can cause spurious quasi-dc currents in power systems; these are termed solar-induced-currents (SIC). A summary of SIC data recorded on over 30 power systems across the United States is presented, and power system effects are discussed. The important problem of internal localized heating in power transformers due to SIC is presented, as well as a consideration of possible methods of mitigation of the SIC.

Polyaspartimides: Condensation of aromatic diamines and bismaleimide compounds

Abstract: A detailed investigation of the condensation of aromatic amines and maleimide compounds was conducted by the use of model compounds. Weak Bronsted acids were found to have a marked catalytic effect on the reaction. By using glacial acetic acid as the reaction medium, a number of model aspartimide compounds were prepared. Aromatic diamines and bismaleimide compounds were condensed to high polymers in cresol containing a small amount of a protonic acid catalyst. Polymers having a variety of novel backbone structures were prepared and their physical properties studied.

Method for making polyetherimides and products produced thereby

Abstract: A method is provided for making polyetherimides involving the reaction of aromatic bis(ether anhydride)s and organic diamines in the presence of a phenolic solvent. The resulting polyetherimide-phenolic solvent mixture can be employed as a wire coating enamel.

High strength organopolysiloxane compositions

Abstract: There is provided an organopolysiloxane composition combining high strength with exceptionally good elongation, which composition comprises a first component, a mixture of two vinylcontaining polysiloxanes or blends of vinyl-containing polysiloxanes, one of which is a high viscosity polysiloxane or a blend of high viscosity polysiloxanes, the other is a low viscosity polysiloxane or a blend of low viscosity vinylcontaining polysiloxanes, a filler and an effective amount of a platinum catalyst. The second component comprises a hydrogen-containing silane or polysiloxane. When it is desired to cure the composition into an elastomer the first component is mixed with the second component, that is, the hydrogen containing silane or polysiloxane and the mixture is allowed to cure either at room temperature or at elevated temperatures. Part of the total high viscosity vinylcontaining polymer can be mixed with the second component.

Combined steam turbine and gas turbine power plant control system

Abstract: A combined cycle power plant has a number of gas turbines each feeding exhaust gas to an associated heat recovery steam generator to generate steam which is supplied to a common header. Provision can also be made for supplementary firing of the heat recovery steam generator to produce additional steam flow. The combined cycle plant also has a steam turbine with a special control system to control steam pressure in the header and to supply the balance of the plant load. An overall combined plant control system assigns load to the individual gas turbine control systems, while the steam turbine control system controls steam pressure in the common header. The steam pressure level setpoint is ramped between selected operating pressure levels when adding or removing load, in accordance with the steam turbine valve positions, in order to achieve optimum operation of the steam turbine. A steam bypass valve control system is used to control pressure in the header during startup, and a supplementary firing control for the heat recovery steam generators may be included to achieve peak loads.

Preparation of asymmetric polymer membranes

Abstract: A method is disclosed for the preparation (by the utilization of a proper solvent system) of dry asymmetric membranes comprising a porous layer of interconnected crystals of polymer material. Membranes of many polymer materials may be optionally prepared either with or without a dense surface layer as one face thereof. In either case the porous layer is structured with graded porosity. A three-component casting solution is prepared containing the polymer, a first good volatile solvent for the polymer and (relative to the first solvent) a poor less-volatile solvent for the polymer, which is miscible with the good solvent. A membrane is cast at room temperature, allowed to desolvate at room temperature for a short time and is then immersed in a precipitating agent, that is miscible with both the aforementioned solvents but is a non-solvent for the polymer. The membrane is then permitted to dry.

Method for removing photoresist from substrate

Abstract: A solvent free method is provided for effecting the complete removal of photoresist from a substrate at temperatures up to about 260* C, utilizing in combination with a mixture of oxygen and ozone, an ultraviolet radiation discharge lamp capable of generating at least 100 milliwatts per square centimeter of ultraviolet light on the substrate surface.

Solvent crazing of “dry” polystyrene and “dry” crazing of plasticized polystyrene

Abstract: The critical strain ec for crazing of polystyrene in each of a variety of organic liquids has been measured along with the degree of swelling of the polymer by the liquid and the attendant reduction in the glass transition temperature Tg of the polymer. The critical strain for the crazing in air and the Tg of each of a set of specimens molded from mixtures of o-dichlorobenzene and polystyrene have also been determined. Correlations of ec with Tg in the two cases are identical within experimental error for the first 40°C of Tg reduction; these results imply (1) that organic liquids do not exercise a significant surface energy role in solvent crazing and (2) that their only roles are associated with flow processes. Correlation of solvent crazing ec with solubility parameter of the crazing fluid is very poor for several reasons that are discussed.

Electrical Properties of ZnO‐Bi2O3 Ceramics

Abstract: The nonlinear volt-ampere characteristics and small-signal ac capacitance and resistance of sintered ZnO containing 0.5 mol% Bi2O3 were measured. Many of the electrical properties are related directly to the microstructure, which consists of conductive ZnO grains separated by a continuous amorphous Bl2O3, phase. The origin of the nonlinear conduction in the intergranular phase was confirmed by experiments with evaporated thin films. The proposed conduction mechanism in varistors containing ZnO and Bi2O3 is a combination of hopping and tunneling in the amorphous phase.

Electric circuit breaker static trip unit with thermal override

Abstract: A polyphase circuit breaker having a static trip control circuit for tripping the circuit the circuit breaker upon the sensing of overcurrent and ground fault conditions of adjustable predetermined levels and duration is provided with a temperature override to safeguard the control circuit and its components against insulation damage and malfunction at excessive ambient temperatures. A voltage divider network comprising a resistor having a fixed resistance and a thermistor having a resistance which changes significantly with temperature change is connected to the base of a transistor to control the conduction of the transistor at about 80* C to cause the energization of the trip coil of the circuit breaker.

Physiological waveform detector

Abstract: A physiological waveform detector such as for cardiac R-wave and blood pressure uses a comparator to compare the derivative of the waveform signal with a reference signal representing some percentage of the magnitude of the derivative of the waveform. If the derivative is of sufficient magnitude to trip the comparator a timing circuit begins counting. If the comparator remains tripped for a predetermined interval, the waveform is considered to be the desired one. Means are provided for detecting waveform peaks and valleys. The detector recognizes desired waveforms by two characteristics, one being magnitude and the other being duration.

Manifold nebulizer system

Abstract: A manifold nebulizer system for use in a breathing circuit. The system includes a nebulizer module and an exhaust module. The nebulizer module consists of a vial to contain liquid and has structure for producing an aerosol of liquid particles for entrainment in a stream of gas. The exhaust module has a valve for facilitating inhalation of the aerosol by the patient and removal of exhaled gases received from the patient. Adjustable surfaces are on the modules to permit relative movement therebetween. In this manner, the manifold nebulizer is capable of assembly into a multiplicity of flow line arrangements and positions.