Showing papers by "United States Department of Energy published in 1988"

Influence of harmonics on power distribution system protection

Abstract: The effects of nonsinusoidal voltages and currents on the performance of static underfrequency and overcurrent relays are experimentally studied. The tests were conducted in such a way that the frequency, amplitude and phase shift of individual harmonics could be adjusted in a controlled manner by using a waveform generator with a phase-locking circuit. The relationship between the harmonic currents and voltages was modeled in terms of the power system impedance within residential distribution systems. It was found that for harmonic voltage and current amplitudes (as they occur in distribution systems), underfrequency relays and the time delay operation of overcurrent relays show a marked deterioration in performance. The instantaneous operating characteristics of overcurrent relays, however, are hardly affected by the presence of harmonic currents. >

Chromosomal aberration and sister-chromatid exchange frequencies in peripheral blood lymphocytes of a large human population sample.

Abstract: In order to assess the potential of cytogenetic determinations on peripheral blood lymphocytes as a means of monitoring human populations subject to low level occupational and environmental exposures to chemical mutagens and carcinogens, accurate baseline data are required. Accordingly, we have determined mean frequencies of chromosomal aberrations and of sister-chromatid exchanges, their variances, and the sources of this variance in a cohort of 353 healthy employees of the Brookhaven National Laboratory. A detailed protocol was adopted for blood sampling, lymphocyte culture, cytogenetic preparation and scoring in order to minimize variation from these potential sources. Scoring was divided between the Oak Ridge and the Brookhaven groups with duplicate scoring sufficient to evaluate and minimize the effect of any differences between laboratories or between individual scorers. In all, the data include 71,950 cells scored for chromosomal aberrations and 16,898 cells scored for sister-chromatid exchanges. The mean unadjusted frequency of sister-chromatid exchanges was 8.29 +/- 0.08/cell. As reported in other studies, cigarette smoking very significantly influenced sister-chromatid exchange frequencies; in our study the mean for smokers was 9.0 +/- 0.2, while that for non-smokers was 8.1 +/- 0.1/cell. The mean frequency was statistically higher in females than in males, regardless of smoking status. On the other hand, age of the subject did not significantly influence sister-chromatid exchange frequencies. Curiously, the subject's total white cell count did influence sister-chromatid exchange frequency. No other source of variation was found. The frequencies of chromosomal aberrations of all types were determined. The frequency of the most common unequivocal chromatid type, the chromatid deletion, was 0.81 +/- 0.05%, that of the most common unequivocal chromosome type, the dicentric, was 0.16 +/- 0.02%. No statistically significant influence was found of age or sex, nor of any other parameter tested, on the frequency of any chromosomal aberration type, with the single exception of long acentric fragments, often "supernumerary", believed to represent X chromosomes precociously separated at the centromere. Such fragments were significantly more frequent in samples from females than those from males, and showed a significant positive regression on age.

Electrode assembly for use in a solid polymer electrolyte fuel cell

Abstract: A gas reaction fuel cell may be provided with a solid polymer electrolyte membrane. Porous gas diffusion electrodes are formed of carbon particles supporting a catalyst which is effective to enhance the gas reactions. The carbon particles define interstitial spaces exposing the catalyst on a large surface area of the carbon particles. A proton conducting material, such as a perfluorocarbon copolymer or ruthenium dioxide contacts the surface areas of the carbon particles adjacent the interstitial spaces. The proton conducting material enables protons produced by the gas reactions adjacent the supported catalyst to have a conductive path with the electrolyte membrane. The carbon particles provide a conductive path for electrons. A suitable electrode may be formed by dispersing a solution containing a proton conducting material over the surface of the electrode in a manner effective to coat carbon surfaces adjacent the interstitial spaces without impeding gas flow into the interstitial spaces.

Method for rapid base sequencing in dna and rna

Abstract: A method is provided for the rapid base sequencing of DNA or RNA fragments wherein a single fragment of DNA or RNA (40) is provided with identifiable bases (A, C, G) and suspended in a moving flow stream. An exonuclease (20) sequentially cleaves individual bases from the end of the suspended fragment. The moving flow stream (24) maintains the cleaved bases in an orderly train for subsequent detection and identification. In a particular embodiment, individual bases forming the DNA or RNA fragments are individually tagged with a characteristic fluorescent dye. The train of bases is then excited to fluorescence with an output spectrum characteristic of the individual bases (26). Accordingly, the base sequence of the original DNA or RNA fragment can be reconstructed.

Multilayer diffraction grating

Abstract: This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages.

The CDF central electromagnetic calorimeter

Abstract: The central electromagnetic calorimeter for the Collider Detector at Fermilab uses a hybrid design with scintillator and wavelength shifter for energy measurement and an embedded strip chamber for position determination and longitudinal shower development. Complementary calibration systems are incorporated in the design. Calorimeter characteristics and performance are summarized. An average energy resolution, σ(E) E , of 13.5%√E sin θ (with E in GeV), and a position resolution of ±2 mm at 50 GeV are measured.

Sol-gel antireflective coating on plastics

Abstract: An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof The film is particularly useful for coating plastics

Interspecific scaling of toxicity data.

Abstract: This paper reexamines the scaling approaches used in cancer risk assessment and proposes a more precise body weight scaling factor. Two approaches are conventionally used in scaling exposure and dose from experimental animals to man: body weight scaling (used by FDA) and surface area scaling (BW/sup 0.67/ - used by EPA). This paper reanalyzes the Freireich et al. (1966) study of the maximum tolerated dose (MTD) of 14 anticancer agents in mice, rats, dogs, monkeys, and humans, the dataset most commonly cited as justification for surface area extrapolation. This examination was augmented with an analysis of a similar dataset by Schein et al. (1970) of the MTD of 13 additional chemotherapy agents. The reanalysis shows that BW/sup 0.75/ is a more appropriate scaling factor for the 27 direct-acting compounds in this dataset.

Calibration factors for Ge detectors used for field spectrometry.

Abstract: Calibration factors to convert a measured full-absorption peak count rate to activity in the soil and dose rate in air are given for Ge detectors that are used for field measurements of radionuclides. The appropriate factors for a given detector are derived using three primary parameters: the manufacturer's quoted efficiency at 1332 keV relative to a 7.6 cm (3 in.) long by 7.6 cm (3 in.) diameter NaI(Tl) detector, the detector's orientation in the field (up or down) and the Ge crystal length/diameter ratio. The accuracy of the results obtained by using this simplified calibration technique is estimated to be 10-15%.

Superconductivity and magnetism in the high TC copper oxides

Abstract: The occurrence of long- and/or short-range magnetic ordering in La2−zCuO4−y, La2−xSrxCuO4−y and YBa2Cu3O7−x is reviewed and discussed with respect to the occurrence of high Tc superconductivity in these systems.

Hydrolysis of cellulose by saturating and non-saturating concentrations of cellulase: implications for synergism

Abstract: Hydrolysis of Cellulose by Saturating and Non–Saturating Concentrations of Cellulase: Implications for Synergism

Crystal diffraction lens with variable focal length

Abstract: A method and apparatus for altering the focal length of a focusing elemento one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels.

Heavy quarks on the lattice

Abstract: A method of treating heavy quarks is applied to lattice Q.C.D. for heavy quar masses (mH) and lattice spacing (a) satisfying the condition mHa > 1. Explicit applications to the measurement of heavy-light meson masses, decay constants, and mixing parameters are presented. Numerical results for B mesons are obtained on a 82 × 16 × 24 lattice with β = 5.7.

CDF Central Muon Detector

Abstract: Design, construction and performance characteristics of the streamer chambers for the central muon detector at CDF are described. A single hit TDC is used for measurements in the drift (azimuth) direction while charge division is used for measurements along the sense wire (pseudorapidity). The chambers operate in the limited streamer mode with a 50%/50% ratio of argon/ethane bubbled through ethanol. Measurements in a cosmic ray test stand, pion test beam and as part of the CDF detector indicate that an rms resolution of 250 μm in the drift direction and an rms resolution of 1.2 mm along the sense wire are attainable.

Method and device for microwave sintering large ceramic articles

Abstract: A microwave sintering system and method are provided for extremely uniform sintering of large and/or irregular shaped ceramic articles at microwave frequencies of at least 28 GHz in the hundreds of kilowatts power range in an untuned cavity. A 28 GHz, 200 kw gyrotron with variable power output is used as the microwave source connected to an untuned microwave cavity formed of an electrically conductive housing through an overmoded waveguide arrangement which acts in conjunction with a mode promoter within the cavity to achieve unexpected field uniformity. The part to be sintered is placed in the cavity and supported on a removable high temperature table in a central location within the cavity. The part is surrounded by a microwave transparent bulk insulating material to reduce thermal heat loss at the part surfaces and maintain more uniform temperature. The cavity may be operated at a high vacuum to aid in preventing arcing. The system allows controlled increased heating rates of greater than 200° C./min to provide rapid heating of a ceramic part to a selected sintering temperature where it is maintained by regulating the microwave power applied to the part. As a result of rapid heating, the extent of non-isothermal processes such as segregation of impurities to the grain boundaries are minimized and exaggerated grain growth is reduced, thereby strengthening the mechanical properties of the ceramic part being sintered.

Methods of in vivo radiation measurement

Abstract: Methods of and apparatus for in vivo radiation measurements relay on a MOSFET dosimeter of high radiation sensitivity with operates in both the passive mode to provide an integrated dose detector and active mode to provide an irradiation rate detector. A compensating circuit with a matched unirradiated MOSFET is provided to operate at a current designed to eliminate temperature dependence of the device. Preferably, the MOSFET is rigidly mounted in the end of a miniature catheter and the catheter is implanted in the patient proximate the radiation source.

Method and apparatus for the simultaneous display and correlation of independently generated images

Abstract: An apparatus and method for location by location correlation of multiple images from Non-Destructive Evaluation (NDE) and other sources. Multiple images of a material specimen are displayed on one or more monitors of an interactive graphics system. Specimen landmarks are located in each image and mapping functions from a reference image to each other image are calcuated using the landmark locations. A location selected by positioning a cursor in the reference image is mapped to the other images and location identifiers are simultaneously displayed in those images. Movement of the cursor in the reference image causes simultaneous movement of the location identifiers in the other images to positions corresponding to the location of the reference image cursor.

Vibrational localization in amorphous silicon.

Abstract: Localized vibrational modes have been identified in a number of computer-generated models of amorphous silicon. Networks containing coordination defects give rise to extra resonance states at low frequencies. The densities of states, and dynamic structure factors for localized, resonant, and extended modes, are discussed and compared with recent neutron scattering data.

Method for heat treating and sintering metal oxides with microwave radiation

Abstract: A method for microwave sintering materials, primarily metal oxides, is described. Metal oxides do not normally absorb microwave radiation at temperatures ranging from about room temperature to several hundred degrees centrigrade are sintered with microwave radiation without the use of the heretofore required sintering aids. This sintering is achieved by enclosing a compact of the oxide material in a housing or capsule formed of a oxide which has microwave coupling properties at room temprature up to at least the microwave coupling temperature of the oxide material forming the compact. The heating of the housing effects the initial heating of the oxide material forming the compact by heat transference and then functions as a thermal insulator for the encased oxide material after the oxide material reaches a sufficient temperature to adequately absorb or couple with microwave radiation for heating thereof to sintering temperature.