Saturation moments of Gd alloys

Results of saturation magnetization measurements on both a- and b-axis single crystals of alloys of 14.5 atomic percent neodymium in gadolinium, 11.0 atomic percent praseodymium in gadolinium, and 8.3 atomic percent cerium in gadolinium are reported. In addition, saturation magnetization measurements on basal plane single crystals of the pure host gadolinium for each alloy are reported. These results are interpreted in terms of a simple vector model, which indicates that, for these alloys, the total angular momentum vectors of the light rare earth ions are aligned antiparallel to the momentum vectors of the gadolinium ions. This result tends to support the hypothesis that, due to strong spin-orbit coupling, the projection of the spin vector onto the total angular momentum vector, and not the spin vector itself, should enter into the interaction Hamiltonian; *USDOE Report Is-T-982. This work was performed under Contract W-7405-eng-82 with the U.S. Department of Energy

Shear Wave Birefringence In Reverse VSP: An Approach To 3-D Surface P To S Converted Waves

We present an original method to estimate local shear wave birefringence properties for 3-D surface P to S converted waves. To accomplish this we approach the problem in reverse VSP (RVSP), and we show that they are equivalent. The method works in the pre-stack domain and uses the converted P to S waves as hypothetical sources to study the problem under the propagator matrix method in transmission. The importance of this method is that no information is required about layering above the zone of interest to obtain an accurate estimation of the anisotropy parameters. The method involves solving a nonlinear problem in the frequency domain where a global minimization technique called Simulation Annealing is used. The procedure also allows us to estimate the axis of anisotropy independently of the offset angle in the range of angles considered in VSPs and in surface profiles. The proposed method is validated with synthetic RVSP data for two models with different densities of vertical fractures. Results show good accuracy in the estimation of the angle of the fractures for the whole range of offsets. Also, results show a dependence on the frequency and offset ranges considered in the analysis.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumMassachusetts Institute of Technology. Earth Resources Laboratory. Reservoir Delineation Consortiu

I Hates To Get Up Early In The Morn

https://digitalcommons.library.umaine.edu/mmb-vp/3170/thumbnail.jp

I Talked All I Am Going To Talk

Illustration of woman in white dress holding umbrella; Photograph of John Queen with wreath around photograph framehttps://scholarsjunction.msstate.edu/cht-sheet-music/4407/thumbnail.jp

Monitoring CO2 Storage at Cranfield, Mississippi with Time-Lapse Offset VSP – Using Integration and Modeling to Reduce Uncertainty

AbstractA time-lapse Offset Vertical Seismic Profile (OVSP) data set was acquired as part of a subsurface monitoring program for geologic sequestration of CO2. The storage site at Cranfield, near Natchez, Mississippi, is part of a detailed area study (DAS) site for geologic carbon sequestration operated by the U.S. Dept. of Energy's Southeast Regional Carbon Sequestration Partnership (SECARB). The DAS site includes three boreholes, an injection well and two monitoring wells. The project team selected the DAS site to examine CO2 sequestration multiphase fluid flow and pressure at the interwell scale in a brine reservoir. The time-lapse (TL) OVSP was part of an integrated monitoring program that included well logs, crosswell seismic, electrical resistance tomography and 4D surface seismic. The goals of the OVSP were to detect the CO2 induced change in seismic response, give information about the spatial distribution of CO2 near the injection well and to help tie the high-resolution borehole monitoring to the 4D surface data.The VSP data were acquired in well CFU 31-F1, which is the ∼3200 m deep CO2 injection well at the DAS site. A preinjection survey was recorded in late 2009 with injection beginning in December 2009, and a post injection survey was conducted in Nov 2010 following injection of about 250 kT of CO2. The sensor array for both surveys was a 50-level, 3-component, Sercel MaxiWave system with 15 m (49ft) spacing between levels. The source for both surveys was an accelerated weight drop, with different source trucks used for the two surveys.Consistent time-lapse processing was applied to both data sets. Time-lapse processing generated difference corridor stacks to investigate CO2 induced reflection amplitude changes from each source point. Corridor stacks were used for amplitude analysis to maximize the signal-to-noise ratio (S/N) for each shot point. Spatial variation in reflectivity (used to ‘map’ the plume) was similar in magnitude to the corridor stacks but, due to relatively lower S/N, the results were less consistent and more sensitive to processing and therefore are not presented. We examined the overall time-lapse repeatability of the OVSP data using three methods, the NRMS and Predictability (Pred) measures of Kragh and Christie (2002) and the signal-to-distortion ratio (SDR) method of Cantillo (2011). Because time-lapse noise was comparable to the observed change, multiple methods were used to analyze data reliability.The reflections from the top and base reservoir were identified on the corridor stacks by correlation with a synthetic response generated from the well logs. A consistent change in the corridor stack amplitudes from pre- to post-CO2 injection was found for both the top and base reservoir reflections on all ten shot locations analyzed. In addition to the well-log synthetic response, a finite-difference elastic wave propagation model was built based on rock/fluid properties obtained from well logs, with CO2 induced changes guided by time-lapse crosswell seismic tomography (Ajo-Franklin et al., 2013) acquired at the DAS site. Time-lapse seismic tomography indicated that two reservoir zones were affected by the flood. The modeling established that interpretation of the VSP trough and peak event amplitudes as reflectivity from the top and bottom of reservoir is appropriate even with possible tuning effects. Importantly, this top/base change gives confidence in an interpretation that these changes arise from within the reservoir, not from bounding lithology. The modeled time-lapse change and the observed field data change from 10 shotpoints are in agreement for both magnitude and polarity of amplitude change for top and base of reservoir. Therefore, we conclude the stored CO2 has been successfully detected and, furthermore, the observed seismic reflection change can be applied to Cranfield's 4D surface seismic for spatially delineating the CO2/brine interface

Using Borehole Electroseismic Measurements To Detect And Characterize Fractured (Permeable) Zones

We present a new type of field measurement capable of detecting and characterizing fractured (permeable) zones intersecting a borehole. The method is based on measuring electrical fields generated by a borehole Stoneley wave. In this paper, we describe the measurement technique, present field data, and propose a theoretical model, which correctly predicts amplitudes and phases of the electrical fields measured in the borehole experiment. The theoretical model and the field data demonstrate that the measurements of the Stoneley-wave-induced electrical fields can yield information about the interconnected porosity, and possibly about the permeability of the formation around the borehole. We derive an estimate of the interconnected porosity from the field data, and show that it correlates well with the density of fractures intersecting the borehole. Our results suggest that the borehole electroseismic method can be developed into a logging or a VSP tool, with possible applications in reservoir characterization.Massachusetts Institute of Technology. Borehole Acoustics and Logging Consortiu

1995 Data Acquisition Program At The Michigan Reservoir Delineation Research Facility

1995 was the most active year in recent history at the test site. Although the initial year of 1983 saw more work, we were still basking in the glow of the modern "oil boom"; the downsizing crash was ahead of us. In 1983, working around the clock, we recorded 13 VSPs, a suite of logs, a reverse VSP, borehole gravity survey, and a 3-D survey in two months of field time. In 1995, a single, four-man Conoco crew worked ten to twelve hour days, for 70 days, and recorded a massive cross-well, orbital vibrator data set-clearly a Herculean task. This paper outlines the pre-survey planning that took place in anticipation of that effort. In addition, we document the single well data acquisition efforts of Conoco, Inc. and Lawrence .Berkeley Laboratory (LBL), and the dipole logging work of Halliburton Energy Services. These data are in the handling stages and processing has not yet begun

Nucleation and growth of crystals under cirrus and polar stratospheric cloud conditions

Laboratory studies examine phase changes of hygroscopic substances which occur as aerosol in stratosphere and troposphere (sodium chloride, ammonium sulfate, ammonium bisulfate, nitric acid, sulfuric acid), under controlled conditions, in samples volume 1 to 10(exp -4) ml. Crystallization of salts from supersaturated solutions is examined by slowly evaporating a solution drop on a substrate, under controlled relative humidity, until self nucleation occurs; controlled nucleation of ice in a mm capillary U-tube gives a measured ice crystallization velocity at known supercooling. Two states of crystallization occur for regions where hydrates exist. It is inferred that all of the materials readily exist as supersaturated/supercooled solutions; the degree of metastability appears to be slightly enhanced by inclusion of aircraft produced soot. The crystallization velocity is taken as a measure of viscosity. Results suggest an approach to a glass transition at high molality, supersaturation and/or supercooling within the range of atmospheric interest. It is hypothesized that surface reactions occur more readily on solidified particles - either crystalline or glass, whereas volume reactions are more important on droplets with sufficiently low viscosity and volume diffusivity. Implications are examined for optical properties of such particles in the atmosphere. In a separate experiment, crystal growth was examined in a modified thermal vapor diffusion chamber over the range of cirrus temperature (-30 to -70 C) and under controlled supersaturation and air pressure. The crystals grew at a velocity of 1-2 microns/s, thickness 60-70 micron, in the form of thin column crystals. Design criteria are given for a system to investigate particle growth down to -100 C, (PSC temperatures) where nitric acid particles can be grown under similar control and in the form of hydrate crystals

Near-Surface Scattering From High Velocity Carbonates In West Texas

Seismic data acquired directly over near-surface limestone formations are commonly observed to be of inferior quality. A possible cause for this degradation is scattering in the near-subsurface by, e.g., the weathering layer, rough free-surface topography, or heterogeneities such as cavities or clusters of vugs. We applied different numerical scattering schemes to study the effects of each of these three scattering mechanisms. For a particular dataset acquired in West Texas, we find that a weathering layer is the dominant cause of noise on records acquired in valleys. However on mesas, nearsubsurface heterogeneity is the primary cause of scattered wave-energy. Topography turned out to be of only secondary importance. As additional attributes, we use energy-density and energy-flux vectors to study the frequency dependence of the different scattering models. These attributes allow us to study where energy concentrates and in which direction it flows. For example, we observed that near sub-surface heterogeneities build up waveguides which efficiently trap seismic energy near the surface.Massachusetts Institute of Technology. Borehole Acoustics and Logging Consortiu

Comparing the impact of primary care practice design in two inner city UK homelessness services

Background: Specialist homeless primary health care services in the United Kingdom have arisen from the need for bespoke approaches to providing health care for people experiencing homelessness but descriptions of the design characteristics of homeless health services together with associated long-term condition (LTC) prevalence, health care utilization, and prescribing remain unexplored, thereby limiting our understanding of potential impact of service configuration on outcomes. Aim: Description of specialist homeless general practitioner services in Glasgow and Edinburgh, in terms of practice design (staff, skill mix, practice systems of registration, and follow-up); and exploration of the potential impact of differences on LTC prevalence, health care utilization, and prescribing. Method: Patient data were collected from computerized general practitioner records in Glasgow (2015, n = 133) and Edinburgh (2016, n = 150). Homeless health service configuration and anonymized patient data, including demographics, LTCs service utilization, and prescribing were summarized and compared. Results: Marked differences in infrastructure emerged between 2 practices, including the patient registration process, segmentation versus integration of services, recording systems, and the availability of staff expertise. Patient characteristics differed in terms of LTC diagnoses, health care utilization and prescribing. Higher rates of recorded mental health and addiction problems were found in Edinburgh, as well as higher rates of physical LTCs, for example, cardiovascular and respiratory conditions. There were significantly higher rates of consultations with nurses and other staff in Edinburgh, although more patients had consultations with pharmacists in Glasgow. Medication adherence was low in both cohorts, and attendance at referral appointments was particularly poor in Glasgow. Conclusion: Service design and professional skill mix influence recording of LTCs, service uptake, and identification and management of health conditions. Service configuration, professional skill mix, and resources may profoundly affect diagnoses, utilization of health care, and prescribing. Attention to homeless service design is important when providing care to this disadvantaged patient group