Showing papers by "United States Department of Energy published in 1987"
TL;DR: In this paper, the ARGUS detector at the DORIS II storage ring has been used in three different ways for B0-B 0 mixing in ϒ (4S) decays.
459 citations
TL;DR: In this paper, a new method was used to produce uniaxially aligned small single crystals of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-//sub delta.
Abstract: A new method has been used to produce uniaxially aligned small single crystals of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-//sub delta/. The superconducting critical current deduced from magnetization data is strongly field dependent and highly anisotropic. In the basal plane at T = 4.2 K we estimate that the critical current at zero field is in excess of 10/sup 7/ A/cm/sup 2/.
324 citations
TL;DR: In this article, a Monte Carlo calculation of the gluon propagator in the Landau gauge in SU(3) lattice gauge theory is described, and the results of calculations at β = 5.6 (200 43 × 8 lattices), β = 4.8 (400 43 × 10 lattices) and β = 6.0 (100 43 × 6 lattices).
230 citations
TL;DR: The ion temperature and the deuterium-fusion neutron yields were significantly higher than for previous tokamak experiments and the low initial densities were achieved by operation of the Tokamak Fusion Test Reactor with low plasma currents and by extensive limiter conditioning.
Abstract: Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities (n/sub e/(0)approx. =10/sup 19/ m/sup -3/) were characterized by T/sub e/(0) = 6.5 keV, T/sub i/(0) = 20 keV, n/sub e/(0) = 7 x 10/sup 19/ m/sup -3/, tau/sub E/ = 170 msec, ..beta../sub t//sub h//sub e//sub t//sub a/ = 2, and a d(d,n)/sup 3/He neutron emission rate of 10/sup 16/ sec/sup -1/. The ion temperature and the deuterium-fusion neutron yields were significantly higher than for previous tokamak experiments. The low initial densities were achieved by operation of the Tokamak Fusion Test Reactor with low plasma currents (less than or equal to1 MA) and by extensive limiter conditioning.
210 citations
TL;DR: In this article, a detailed theoretical study of vibrational-rotational excitation and reaction in collisions of CO2 with 1.9-2.6 eV hydrogen atoms is presented.
Abstract: We present a detailed theoretical study of vibrational–rotational excitation and reaction in collisions of CO2 with 1.9–2.6 eV hydrogen atoms. Minima and saddle points on the potential surface have been characterized using ab initio configuration interaction calculations, and a global surface has been developed by a combination of many-body expansion and surface-fitting methods. The collision dynamics have been studied using quasiclassical trajectories, with the CO2 vibrational states characterized by a Fourier-transform action calculation. For non-reactive scattering there is reasonable correlation between the vibrational modes that are excited and the regions of the potential surface sampled during the collisions. Most of the lower states of CO2 are excited by direct collisions that do not sample potential wells. Collisions which do sample wells lead to short-lived HOCO and HCO2 complexes, in which either the H dissociates to produce highly excited overtone and combination states of CO2, or a CO bond breaks to give OH + CO having close to statistical vibrational–rotational distributions. Comparison of cross-sections and final-state distributions with experiment is excellent for the reactive collisions, and is good on a relative but not absolute basis for the non-reactive collisions.
177 citations
TL;DR: In this article, internal standardization is employed to compensate for ionization suppression in inductively coupled plasma-mass spectrometry (ICP-MS) systems, and it is shown that an internal standard is most effective when it is close in mass and ionization energy to the analyte.
Abstract: Internal standardization is employed to compensate for ionization suppression in inductively coupled plasma-mass spectrometry (ICP-MS). By examination of the response of over 50 elements to a sodium matrix under different operating conditions, it is apparent that an internal standard is most effective when it is close in mass and ionization energy to the analyte. The extent of suppression and the relative order of suppression of various analyte elements can differ for various matrix elements. Generally, precision was improved by the use of internal standardization; the extent of improvement differed for different analyte elements and operating conditions. A comparison between ICP-MS with ultrasonic and pneumatic nebulization is described. The ultrasonic nebulizer usually exhibits better sensitivity and detection limits for analyte elements, unless the extent of suppression induced by the concomitant matrix is very high.
173 citations
TL;DR: The daily intake of long-lived alpha-emitting members of the U, Th and Ac series by New York City residents has been estimated from measurements of diet, water and air samples.
Abstract: The daily intake of long-lived alpha-emitting members of the U, Th and Ac series by New York City residents has been estimated from measurements of diet, water and air samples. The total daily intakes from inhalation, food and water consumption in mBq are 18 (234U), 0.7 (235U), 16 (238U), 6 (230Th), 4 (232Th) and 52 (226Ra). From this, we infer that the total daily intakes of 228Th and 228Ra are 4 and 35 mBq, respectively.
125 citations
116 citations
TL;DR: In this paper, the facilitated transport of CO2 through ion exchange membranes containing organic amine counterions was studied, and the transport data support a mobile, reactive-carrier facilitated transport mechanism with a carbamate zwitterion complex.
Abstract: The facilitated transport of CO2 through ion exchange membranes containing organic amine counterions was studied. Steady state CO2 fluxes were measured from pure gas streams and mixtures with CH4. Facilitation factors for CO2 up to 26.7 were calculated from transport data. Transport measurements were binary mixtures of CO2 and CH4 yielded ratios of CO2 flux to CH4 flux ranging from 29.0 to 264. Conversion of flux ratios to permeabilities yielded separation factors up to 551 for CO2 over CH4, which are compared to literature data for polymeric membranes. The transport data support a mobile, reactive-carrier facilitated transport mechanism with a carbamate zwitterion complex. Effective diffusivities for CO2 and the carrier-gas complex were determined from transport data. A reaction equilibrium model predicted facilitation factors that were in very good agreement with experimental values. Potential applications are also discussed.
116 citations
Patent•
30 Nov 1987TL;DR: In this paper, a passageway in the construction directs flat cells near to the area of one dimensional convergence in the sheath fluid to provide proper orientation of flat cells at fast rates.
Abstract: An obstruction across the flow chamber creates a one dimensional convergence of a sheath fluid. A passageway in the construction directs flat cells near to the area of one dimensional convergence in the sheath fluid to provide proper orientation of flat cells at fast rates.
80 citations
Patent•
02 Apr 1987TL;DR: In this article, a pre-treatment with hydrogen at temperatures in the range of 250° to 300° C was used to make pyrolyzate oil amendable to hydrotreatment without substantial coking problems.
Abstract: Pyrolyzate oil is made amendable to hydrotreatment without substantial coking problems by means of pre-treatment with hydrogen at temperatures in the range of 250° to 300° C.
TL;DR: In this paper, the authors developed thermal barrier coatings for turbine airfoil applications, which could allow up to a 149°C (300°F) increase in turbine inlet temperature without a penalty in service life.
TL;DR: In this article, the stability of β-VOPO4 and (VO)2P2O7 under conditions of n-butane and 1-butene oxidation was investigated using the complementary techniques of in situ laser Raman spectroscopy, X-ray diffraction, and Xray photoelectron spectrographs.
TL;DR: In this article, a thermogravimetric analysis system (TGA) was used to determine the reactivity of coal chars in oxidizing atmosphere using isothermal or non-isothermal techniques.
Patent•
23 Mar 1987TL;DR: In this paper, a two-frequency Zeeman effect laser was used to detect and characterize particles using light scattered from the laser beam, and a 250 kHz beat frequency was recorded from an individual particle traversing the focused output of the laser in a flow cytometer.
Abstract: Interferometric apparatus and method for detection and characterization of particles using light scattered therefrom. Differential phase measurements on scattered light from particles are possible using the two-frequency Zeeman effect laser which emits two frequencies of radiation 250 kHz apart. Excellent discrimination and reproducibility for various pure pollen and bacterial samples in suspension have been observed with a single polarization element. Additionally, a 250 kHz beat frequency was recorded from an individual particle traversing the focused output from the laser in a flow cytometer.
TL;DR: A principal components analysis of morphological, phenological, and agronomic metrical traits for 375 lines randomly selected from 15 landraces revealed a clinal pattern, with the northern and southern areas forming the extremes.
Abstract: Bean germplasm collections in northern Malawi revealed the existence of diverse landraces, which have probably been maintained by the local farmers as heterogeneous mixtures since the precolonial introduction of Phaseolus vulgaris into eastern Africa. The various seed types comprising these mixtures are known by an array of local names, reflecting farmer perceptions of seed color and pattern, eating quality, plant structure, origin, and other characteristics. A principal components analysis of morphological, phenological, and agronomic metrical traits for 375 lines randomly selected from 15 landraces revealed a clinal pattern, with the northern and southern areas forming the extremes. Genetic distances, based on the first six PCs, indicated greater between-area variability than within-area variability. Bean landrace diversity in Malawi is likely the result of a complex interplay among forces that generate variability such as outcrossing and human and environmental selection.
TL;DR: Experiments determined that outcrossing does occur at a low level among beans in Malawi and can result in the generation of many new seed phenotypes, a foundation for understanding the generation and maintenance of variability in these bean landraces.
Abstract: Bean (Phaseolus vulgaris) landraces in northern Malawi were found to be heterogeneous for many qualitative and quantitative traits. An earlier 21- character evaluation of 25 lines in 15 landraces found significant differences in all characters among lines and among landraces. The present study has concentrated on two factors that are likely to be involved in the generation and maintenance of this heterogeneity: seed- handling practices and natural outcrossing. Seed- handling practices during harvest, storage, and marketing at the village, local market, and national levels were found to result in physical and usually nonselective mixing of many seed types. Experiments determined that outcrossing does occur at a low level among beans in Malawi and can result in the generation of many new seed phenotypes. A scenario was developed integrating seed- handling practices and outcrossing that lays a foundation for understanding the generation and maintenance of variability in these bean landraces. The process whereby landrace heterogeneity arises and the ways it is maintained, if understood, should assist plant breeders in the development of improved germplasm for subsistence farmers.
TL;DR: A controlled-atmosphere, programmed-temperature, oxidation apparatus has been constructed and used to characterize organic-sulphur distribution in coals, partially desulphurized coals and model systems as discussed by the authors.
TL;DR: Etude du frittage de poudres de zircone stabilisee par CaO ou ou Y 2 O 3, de Y 2 o 3 et de Al O 3 in presence de divers additifs.
Abstract: Etude du frittage de poudres de zircone stabilisee par CaO ou Y 2 O 3 , de Y 2 O 3 et de Al 2 O 3 en presence de divers additifs
Patent•
07 Dec 1987TL;DR: In this paper, a photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductor circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses.
Abstract: A photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test. Second PCEs are connected along the transmission line to sample the signals on the transmission line when excited into conductance by short second laser light pulses, spaced apart in time a variable period from the first laser light pulses. Electronic filters connected to each of the second PCEs act as low-pass filters and remove parasitic interference from the sampled signals and output the sampled signals in the form of slowed-motion images of the signals on the transmission line.
Patent•
05 Nov 1987TL;DR: In this article, an electrorefining process and apparatus for the recovery of uranium and a mixture of plutonium from spent fuel using an electrolytic cell having a lower molten cadmium pool containing spent nuclear fuel was described.
Abstract: An electrorefining process and apparatus for the recovery of uranium and a mixture of uranium and plutonium from spent fuel using an electrolytic cell having a lower molten cadmium pool containing spent nuclear fuel, an intermediate electrolyte pool, an anode basket containing spent fuel, and two cathodes, the first cathode composed of either a solid alloy or molten cadmium and the second cathode composed of molten cadmium. Using this cell, additional amounts of uranium and plutonium from the anode basket are dissolved in the lower molten cadmium pool, and then substantially pure uranium is electrolytically transported and deposited on the first alloy or molten cadmium cathode. Subsequently, a mixture of uranium and plutonium is electrotransported and deposited on the second molten cadmium cathode.
TL;DR: In this paper, the ARGUS detector at the e + e− storage ring DORIS II has been used to study the colour-suppressed decays B → J ψ X and B→ψ′ X.
TL;DR: In this article, the ARGUS detector at DORIS II has analyzed tau decays into π − π− π + π 0 ν τ with a branching ratio of 4.2±0.9.
TL;DR: In this paper, an ideal-flow reactor model for SO2 removal was formulated based on a sulfation reaction kinetics model developed using data from a microbalance reactor, and experimental data obtained from a fluidized-bed reactor having a cross section measuring 1.02 m by 1.22 m (40 in. by 48 in.) were used to validate the model.
Abstract: The Fluidized-Bed Copper Oxide Process is a regenerative process for the simultaneous removal of both sulfur dioxide (SO2) and nitrogen oxides (NOX) from the flue gas of coal-fired boilers. An ideal-flow reactor model for SO2 removal was formulated based on a sulfation reaction kinetics model developed using data from a microbalance reactor. Experimental data obtained from a fluidized-bed reactor having a cross section measuring 1.02 m by 1.22 m (40 in. by 48 in.) were used to validate the model. The variables in the model were systematically varied to predict reactor performance under different operating conditions. The process variables studies were (1) sorbent copper content, (2) reactor bed depth, and (3) reaction temperature. The reactor performance predictions showed that increasing the copper content of the sorbent from 5 percent to 7 percent would lower the required sorbent recirculation rate by 30 percent. The expanded-bed depth in the reactor was also an important parameter. Effective performance of the process can be obtained with lower sorbent recirculation rates if the expanded-bed depth in the reactor is increased.
TL;DR: In this paper, it was shown that the asymptotic formula is valid for power means, Dresher means, mixed means, and hypergeometric means, provided only that M satisfies very general hypotheses.
TL;DR: In this article, the authors reconstructed B mesons in five decay channels of the type B →D ∗ ±nπ(n=1,2,3) using data accumulated by the ARGUS experiment at the e + e − storage ring DORIS II at DESY.
Patent•
29 May 1987TL;DR: In this article, a one-step combustion process for the synthesis of dense aluminum nitride compositions is described, which comprises igniting pure aluminum powder in a nitrogen atmosphere at a pressure of about 1000 atmospheres or higher.
Abstract: A one step combustion process for the synthesis of dense aluminum nitride compositions is disclosed. The process comprises igniting pure aluminum powder in a nitrogen atmosphere at a pressure of about 1000 atmospheres or higher. The process enables the production of aluminum nitride bodies to be formed directly in a mold of any desired shape.
Patent•
15 Jan 1987TL;DR: An accelerator module for a data flow computer includes an intelligent memory as mentioned in this paper, which assigns locations for holding data values in correspondence with arcs leading to a node in a data dependency graph.
Abstract: An accelerator module for a data flow computer includes an intelligent memory The module is added to a multiprocessor arrangement and uses a shared tagged memory architecture in the data flow computer The intelligent memory module assigns locations for holding data values in correspondence with arcs leading to a node in a data dependency graph Each primitive computation is associated with a corresponding memory cell, including a number of slots for operands needed to execute a primitive computation, a primitive identifying pointer, and linking slots for distributing the result of the cell computation to other cells requiring that result as an operand Circuitry is provided for utilizing tag bits to determine automatically when all operands required by a processor are available and for scheduling the primitive for execution in a queue Each memory cell of the module may be associated with any of the primitives, and the particular primitive to be executed by the processor associated with the cell is identified by providing an index, such as the cell number for the primitive, to the primitive lookup table of starting addresses The module thus serves to perform functions previously performed by a number of sections of data flow architectures and coexists with conventional shared memory therein A multiprocessing system including the module operates in a hybrid mode, wherein the same processing modules are used to perform some processing in a sequential mode, under immediate control of an operating system, while performing other processing in a data flow mode
01 Aug 1987-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: Theoretical considerations and experimental data are used to demonstrate the basic behaviour of the self-absorption effect of a sample matrix in gamma ray spectrometry, particularly as it relates to the analysis of 210Pb in environmental media as discussed by the authors.
Abstract: Theoretical considerations and experimental data are used to demonstrate the basic behaviour of the self-absorption effect of a sample matrix in gamma ray spectrometry, particularly as it relates to the analysis of 210Pb in environmental media. The results indicate that it may not be appropriate to apply the commonly used self-absorption function in all cases.
TL;DR: In this article, a low-temperature devolatilization (slow heating to 500° to 650°C in a batch reactor) of coal in the presence of CaO (10 to 20 weight percent) can produce a relatively high-quality liquid fuel (containing low sulfur, low oxygen, low viscosity, low Conradson carbon residue, and low pour point) compared to that occurring in rapid heat-up processes, the residence time of both the liquid and gaseous products is significantly greater in either a batch or fixed-bed slow-heating
Abstract: The most recent studies of coal devolatilization processes have emphasized maximisation of liquids yield by use of extreme process conditions such as high heating rate The liquids produced by such processes are often unsuitable for utilization without extensive upgrading The aim of the study reported here was to optimize product quality by use of relatively mild conditions Low-temperature devolatilization (slow heating to 500° to 650°C in a batch reactor) of coal in the presence of CaO (10 to 20 weight percent) can produce a relatively high-quality liquid fuel (containing low sulfur, low oxygen, low viscosity, low Conradson carbon residue, and low pour point) Compared to that occurring in rapid heat-up processes, the residence time of both the liquid and gaseous products is significantly greater in a batch or fixed-bed slow-heating system It is proposed that this increased residence time facilitates greater secondary reactions of the primary products in the coal bed with the added CaO The H