Thermal conductivity and electrical resistivity of porous materials

Process for determining thermal conductivity and electrical resistivity of porous materials is described. Characteristics of materials are identified and used in development of mathematical models. Limitations of method are examined

Fundamental study of transpiration cooling

Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable

Assessment of alternative strategies for sludge disposal into deep ocean basins off Southern California

The general framework of engineering alternatives for regional ocean sludge disposal is well described in a report by Raksit, and will not be repeated here. The various ocean disposal alternatives are less costly than all land-disposal and incineration/pyrolysis systems studied. Even though ocean sludge disposal is currently contrary to both state and federal regulations, it is hoped that this study will advance our scientific and engineering knowledge of the behavior and effects of sludge discharge in deep water, in case the regulatory policy is reexamined in the future. With this report we hope we have demonstrated the potential and difficulties of some new modeling techniques for predicting the effects of sludge discharge in the ocean. In the future. we believe it will be possible to formulate policy of ocean sludge discharges with much better case-by-case predictions of impacts for comparison with other alternatives (such as land disposal). not only for the Los Angeles/Orange County areas, but for all coastal urban areas

Variations in coastal temperatures on the southern and central California coast

The results of a time series analysis of several years of coastal ocean temperature records are presented for discussion. The records have been analyzed by using digital filtering, covariance and spectral analysis. The low-frequency component of the temperature signal shows a strong seasonal component in southern California. There is little seasonal fluctuation between Point Conception and Pacific Grove. A period of midwinter warming is apparent in southern California. Intermediate frequency components show strong correlations in southern California with the presence of distinct and substantial temperature events occurring almost simultaneously over distances of the order of 200 km. High-frequency components have a large standard deviation in summer (0.8°C) and a low standard deviation in winter (0.4°C); these components are uncorrelated at stations even a few miles apart. Some coastal stations show a strong possible diurnal component; others, including the offshore islands, show no such components. Morro Bay appears to have an extraordinarily large diurnal component of temperature fluctuation. No attempt has been made in this paper to relate these phenomena to other oceanographic or meteorological variables

Interpretations of results from hydraulic modeling of thermal outfall diffusers for the San Onofre Nuclear Power Plant

This report presents and interpretation of results obtained during the hydraulic model study previously documented in "Hydraulic Modeling of Thermal Outfall Diffusers for the San Onofre Nuclear Power Plant" which described the hydraulic laboratory studies conducted to investigate outfall configurations for the thermal discharge from proposed Units 2 and 3 at the San Onofre Nuclear Generating Station, jointly owned by the Southern California Edison Company and San Diego Gas and Electric Company. A number of different experimental investigations were performed to develop the conceptual design for the new Units 2 and 3 discharge diffusers. The primary reason for the investigations was the new California thermal standards (essentially ambient temperature increment less than 4°F), which in effect precluded the use of shoreline or single outlet discharges for new units and necessitated the use of multiport diffusers. The result of the investigations of different diffuser concepts was the establishment of a preliminary design for the discharge structures for Units 2 and 3, each consisting of a diffuser 2500 ft long containing 76 discharge nozzles with a nominal discharge velocity of 13 ft/sec. This preliminary design was later modified somewhat by the engineers of the Southern California Edison Company (SCE) in consideration of other factors such as structural requirements, cost, construction problems, and more accurate bathymetric details at the site. As a result the final design for each diffuser contains 63 discharge ports of diameters varying from 21.85 to 23.9 inches. The discharge ports are nozzle-riser assemblies at alternate angles of ±25° with respect to the longitudinal axis of the diffuser and 20° up from horizontal. The nozzles are positioned approximately 6 ft from the ocean bottom. The diffusers are aligned perpendicular to shore and extend from approximately 3500 ft to 8500 ft offshore. The performance of the final diffuser design was evaluated in a series of confirming tests. The major results will be summarized and discussed in section 3 of this report. Sections 3 and 4 will also include projections and elaborations on several aspects of the diffuser performance to be expected in the prototype. The possible interactions of the proposed diffuser operation with existing site factors such as ocean currents, water temperature, heat losses, and the existing power plant (Unit 1) will also be discussed in section 4

Anisotropic Dirac fermions in a Bi square net of SrMnBi2

We report the highly anisotropic Dirac fermions in a Bi square net of SrMnBi2, based on a first principle calculation, angle resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the (SrBi)+ layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in SrMnBi2 is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of ~ 8. These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provide a new platform that hosts highly anisotropic Dirac fermions.Comment: 5 pages, 4 figure

Electronic Structure of Electron-doped Sm1.86Ce0.14CuO4: Strong `Pseudo-Gap' Effects, Nodeless Gap and Signatures of Short Range Order

Angle resolved photoemission (ARPES) data from the electron doped cuprate superconductor Sm$_{1.86}$Ce$_{0.14}$CuO$_4$ shows a much stronger pseudo-gap or "hot-spot" effect than that observed in other optimally doped $n$-type cuprates. Importantly, these effects are strong enough to drive the zone-diagonal states below the chemical potential, implying that d-wave superconductivity in this compound would be of a novel "nodeless" gap variety. The gross features of the Fermi surface topology and low energy electronic structure are found to be well described by reconstruction of bands by a $\sqrt{2}\times\sqrt{2}$ order. Comparison of the ARPES and optical data from the $same$ sample shows that the pseudo-gap energy observed in optical data is consistent with the inter-band transition energy of the model, allowing us to have a unified picture of pseudo-gap effects. However, the high energy electronic structure is found to be inconsistent with such a scenario. We show that a number of these model inconsistencies can be resolved by considering a short range ordering or inhomogeneous state.Comment: 5 pages, 4 figure

Self-reported domain-specific and accelerometer-based physical activity and sedentary behaviour in relation to psychological distress among an urban Asian population

Background: The interpretation of previous studies on the association of physical activity and sedentary behaviour with psychological health is limited by the use of mostly self-reported physical activity and sedentary behaviour, and a focus on Western populations. We aimed to explore the association of self-reported and devise-based measures of physical activity and sedentary behaviour domains on psychological distress in an urban multi-ethnic Asian population. Methods: From a population-based cross-sectional study of adults aged 18-79 years, data were used from an overall sample (n = 2653) with complete self-reported total physical activity/sedentary behaviour and domain-specific physical activity data, and a subsample (n = 703) with self-reported domain-specific sedentary behaviour and accelerometry data. Physical activity and sedentary behaviour data were collected using the Global Physical Activity Questionnaire (GPAQ), a domain-specific sedentary behaviour questionnaire and accelerometers. The Kessler Screening Scale (K6) and General Health Questionnaire (GHQ-12) were used to assess psychological distress. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals, adjusted for socio-demographic and lifestyle characteristics. Results: The sample comprised 45.0% men (median age = 45.0 years). The prevalence of psychological distress based on the K6 and GHQ-12 was 8.4% and 21.7%, respectively. In the adjusted model, higher levels of self-reported moderate-to-vigorous physical activity (MVPA) were associated with significantly higher odds for K6 (OR = 1.47 [1.03-2.10]; p-trend = 0.03) but not GHQ-12 (OR = 0.97 [0.77-1.23]; p-trend = 0.79), when comparing the highest with the lowest tertile. Accelerometry-assessed MVPA was not significantly associated with K6 (p-trend = 0.50) nor GHQ-12 (p-trend = 0.74). The highest tertile of leisure-time physical activity, but not work- or transport-domain activity, was associated with less psychological distress using K6 (OR = 0.65 [0.43-0.97]; p-trend = 0.02) and GHQ-12 (OR = 0.72 [0.55-0.93]; p-trend = 0.01). Self-reported sedentary behaviour was not associated with K6 (p-trend = 0.90) and GHQ-12 (p-trend = 0.33). The highest tertile of accelerometry-assessed sedentary behaviour was associated with significantly higher odds for K6 (OR = 1.93 [1.00-3.75]; p-trend = 0.04), but not GHQ-12 (OR = 1.34 [0.86-2.08]; p-trend = 0.18). Conclusions: Higher levels of leisure-time physical activity and lower levels of accelerometer-based sedentary behaviour were associated with lower psychological distress. This study underscores the importance of assessing accelerometer-based and domain-specific activity in relation to mental health, instead of solely focusing on total volume of activity

Hydraulic modeling of thermal outfall diffusers for the San Onofre nuclear power plant

Various hydraulic model tests were performed in connection with the design and performance of the offshore thermal outfalls for the San Onofre Nuclear Generating Station (jointly owned by the Southern California Edison Company and the San Diego Gas and Electric Company)near San Clemente, California. These include model investigations of: (i) the multiple port discharges for the proposed Units 2 and 3, (ii) the existing submerged single outlet from Unit 1, (iii) the discharge of heated water from the Units 2 and 3 intakes during heat treatment, and (iv) hydraulic characteristics of discharge ports. On the basis of these investigations, the diffusion structure for each of the proposed new units was designed to be 2500 feet long aligned perpendicular to shore. The diffuser for Unit 3 will extend from 3500 to 6000 feet from shore, and that for Unit 2 from 6000 to 8500 feet from shore. Each diffuser will have 63 discharge nozzles aimed offshore (±25° from the pipe axis, 20° above horizontal). The momentum of the discharge produces and offshore drift of the diluted warm-water plume. The maximum temperature rise on the surface caused by the discharge was found to decrease with increasing longshore current speed, and the discharge momentum from the jets was effective in preventing significant re-entrainment in the event of reversing or low currents. Although the California thermal discharge requirements specify a maximum surface temperature increase of 4°F (beyond 1000 feet from the discharge structure), the laboratory target maximum was established at 2.5°F, to account for possible model-prototype differences and unmodeled effects. The hydraulic model studies showed that the proposed outfall design meets the laboratory target value for a variety of possible longshore current conditions; therefore, it is predicted that the prototype outfall operation will meet the California thermal discharge requirements