Numerical prediction of 3-D ejector flows

The use of parametric flow analysis, rather than parametric scale testing, to support the design of an ejector system offers a number of potential advantages. The application of available 3-D flow analyses to the design ejectors can be subdivided into several key elements. These are numerics, turbulence modeling, data handling and display, and testing in support of analysis development. Experimental and predicted jet exhaust for the Boeing 727 aircraft are examined

Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures

An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented

Inlet flowfield investigation. Part 2: Computation of the flow about a supercruise forebody at supersonic speeds

A numerical procedure which solves the parabolized Navier-Stokes (PNS) equations on a body fitted mesh was used to compute the flow about the forebody of an advanced tactical supercruise fighter configuration in an effort to explore the use of a PNS method for design of supersonic cruise forebody geometries. Forebody flow fields were computed at Mach numbers of 1.5, 2.0, and 2.5, and at angles-of-attack of 0 deg, 4 deg, and 8 deg. at each Mach number. Computed results are presented at several body stations and include contour plots of Mach number, total pressure, upwash angle, sidewash angle and cross-plane velocity. The computational analysis procedure was found reliable for evaluating forebody flow fields of advanced aircraft configurations for flight conditions where the vortex shed from the wing leading edge is not a dominant flow phenomenon. Static pressure distributions and boundary layer profiles on the forebody and wing were surveyed in a wind tunnel test, and the analytical results are compared to the data. The current status of the parabolized flow flow field code is described along with desirable improvements in the code

Accounting for changing temperature patterns increases historical estimates of climate sensitivity

Eight atmospheric general circulation models (AGCMs) are forced with observed historical (1871–2010) monthly sea surface temperature and sea ice variations using the Atmospheric Model Intercomparison Project II data set. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However, the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a pattern effect, whereby the pattern of observed historical sea surface temperature change gives rise to more negative cloud and longwave clear‐sky feedbacks. Assuming the patterns of long‐term temperature change simulated by models, and the radiative response to them, are credible; this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long‐term Otto et al. (2013, https://doi.org/10.1038/ngeo1836) EffCS median and 5–95% confidence interval from 1.9 K (0.9–5.0 K) to 3.2 K (1.5–8.1 K

Narayanaswamy’s 1971 aging theory and material time

The Bochkov-Kuzovlev nonlinear fluctuation-dissipation theorem is used to derive Narayanaswamy's phenomenological theory of physical aging, in which this highly nonlinear phenomenon is described by a linear material-time convolution integral. A characteristic property of the Narayanaswamy aging description is material-time translational invariance, which is here taken as the basic assumption of the derivation. It is shown that only one possible definition of the material time obeys this invariance, namely the square of the distance travelled from a configuration of the system far back in time. The paper concludes with suggestions for computer simulations that test for consequences of material-time translational invariance. One of these is the "unique-triangles property" according to which any three points on the system's path form a triangle such that two side lengths determine the third; this is equivalent to the well-known triangular relation for time-autocorrelation functions of aging spin glasses [L. F. Cugliandolo and J. Kurchan, J. Phys. A: Math. Gen. 27, 5749 (1994)]. The unique-triangles property implies a simple geometric interpretation of out-of-equilibrium time-autocorrelation functions, which extends to aging a previously proposed framework for such functions in equilibrium [J. C. Dyre, cond-mat/9712222]

Integrated assessment of oyster reef ecosystem services: Macrofauna utilization of restored oyster reefs

Within the Harris Creek Oyster Sanctuary in the Maryland portion of Chesapeake Bay, we evaluated relationships between basic oyster reef characteristics and the abundance and biomass of macrofauna. The eight sites selected for these studies included five restored oyster reef sites and three sites suitable for restoration that had not been restored. These sites encompassed a range of oyster biomass density and were spread throughout the sanctuary area. At each site one month prior to each of four sampling periods, divers filled four wire mesh baskets (0.1m2 surface area x 15 cm depth) with material from the site and embedded them so that the surface was flush with the surrounding substratum. In spring, early summer, late summer and fall of 2015, divers collected baskets and returned them to the laboratory where all macrofauna ≥1 mm were collected from each sample and their identity, abundance and biomass were determined. In addition to the abundance and biomass of oysters, we also assessed the amount of surface as the volume of live oysters along with that of any oyster shells whose surface was at least 50% oxic based on coloration (i.e. black shell was presumed to have been buried below the surface in anoxic conditions). Positive relationships were identified for all three reef characteristics and the three major macrofaunal groups examined. In the majority of seasons, the relationship between both biomass and abundance of the hooked mussel, Ischadium recurvum, as a power function of oyster tissue biomass density, oyster abundance per square meter and surface shell volume. The relationship between oyster reef characteristics and the biomass and abundance of the mud crab, Eurypanopeus depressus, and of the naked goby, Gobiosoma bosc, were always positive but were more variable than that for I. recurvum. These data demonstrate that relationships can be found between oyster reef characteristics and macrofauna abundance and biomass. They further demonstrate that, in many cases, simple measures of reef characteristics such as oyster abundance and shell volume can provide predictions of macrofauna abundance and biomass that are comparable to more labor intensive measures such as oyster tissue biomass

Integrated assessment of oyster reef ecosystem services: Fish and crustacean utilization and trophic linkages

Using a regression design that encompassed the continuum of oyster reef biomass density in Harris Creek, MD, from unrestored reefs to those restored reefs with the greatest oyster biomass, we examined finfish and crustacean utilization of these habitats. Of the eight sites studied, three had not been subject to any restoration activities and five had been planted in 2012 with juvenile oysters set on oyster shell. All sites were sampled in April, June, August, and October 2015. During each sampling period, we assessed abundance, total length and biomass of finfish and examined gut contents to assess the diets of selected finfish species. Of the species collected that were likely to use reefs as habitat or a foraging ground, only striped bass and white perch were sufficiently abundant to support robust statistical analyses. Regression analyses found no clear relationship between oyster biomass density and catch per unit effort, total length or biomass for striped bass or white perch. Analyses of the effects of sampling period and restoration status (restored versus non-restored sites) on fish utilization frequently found an effect of sampling period but rarely found an effect of restoration status. In all cases where differences were detected, they suggested greater utilization of non-restored sites. Overall, data were sparse and the power of statistical analyses was low. Analyses of striped bass and white perch diets suggest that they are using oyster reefs as a foraging ground. Although comparisons of the proportion of striped bass and white perch that contained prey in their stomachs found no difference between those caught on restored sites versus non-restored sites, gut contents of both species contained prey taxa that are likely more abundant on restored oyster reefs than nonrestored sites. As a percentage of total prey wet weight, polychaete worms were the most important component of striped bass diets in both April (50%) and August (47%). Of the polychaete worms identifiable to species, 100% were Alitta succinea, a species found in much greater abundance and biomass on restored oyster reefs than on comparable non-restored sites (Kellogg et al. 2013, Rodney and Paynter 2006). White perch diets were dominated by the ascidian Molgula manhattensis (52%), a species generally found in greater abundance on hard substrates including oyster reefs. Of the identifiable species of fish found in the stomachs of striped bass, 93% by weight were naked gobies (Gobiosoma bosc) or striped blennies (Chasmodes bosquianus), two species found in greater abundance and biomass on restored oyster reefs than nonrestored sites in Chesapeake Bay (Kellogg et al. 2013, Rodney and Paynter 2006). For white perch, naked gobies accounted for 95% of the identifiable fish species by weight. Direct comparisons of white perch and striped bass diets to the prey fields at each sampling site will be conducted as part of a companion project also funded by NOAA Chesapeake Bay Office (Award #: NA13NMF4570209: Integrated assessment of oyster reef ecosystem services: Macrofaunal utilization, secondary production and nutrient sequestration). This companion project will also provide data on abundance, biomass and distribution of small, reef-associated species including naked gobies, striped blennies, and oyster toadfish (Opsanus tau)

Sunshine, rainfall, humidity and child pneumonia in the tropics: time-series analyses

Few studies have formally examined the relationship between meteorological factors and the incidence of child pneumonia in the tropics, despite the fact that most child pneumonia deaths occur there. We examined the association between four meteorological exposures (rainy days, sunshine, relative humidity, temperature) and the incidence of clinical pneumonia in young children in the Philippines using three time-series methods: correlation of seasonal patterns, distributed lag regression, and case-crossover. Lack of sunshine was most strongly associated with pneumonia in both lagged regression [overall relative risk over the following 60 days for a 1-h increase in sunshine per day was 0·67 (95% confidence interval (CI) 0·51–0·87)] and case-crossover analysis [odds ratio for a 1-h increase in mean daily sunshine 8–14 days earlier was 0·95 (95% CI 0·91–1·00)]. This association is well known in temperate settings but has not been noted previously in the tropics. Further research to assess causality is needed

Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data

This paper presents data for supercooled squalane's frequency-dependent shear modulus covering frequencies from 10 mHz to 30 kHz and temperatures from 168 K to 190 K; measurements are also reported for the glass phase down to 146 K. The data reveal a strong mechanical beta process. A model is proposed for the shear response of supercooled liquids. The model is an electrical equivalent-circuit characterized by additivity of the dynamic shear compliances of the alpha and beta processes. The nontrivial parts of the alpha and beta processes are represented by a "Cole-Cole retardation element", resulting in the Cole-Cole compliance function well-known from dielectrics. The model, which assumes that the high-frequency decay of the alpha shear compliance loss varies with angular frequency as $\omega^{-1/2}$, has seven parameters. Assuming time-temperature superposition for the alpha and the beta processes separately, the number of parameters varying with temperature is reduced to four. From the temperature dependence of the best-fit model parameters the following conclusions are drawn: 1) the alpha relaxation time conforms to the shoving model; 2) the beta relaxation loss-peak frequency is almost temperature independent; 3) the alpha compliance magnitude, which in the model equals the inverse of the instantaneous shear modulus, is only weakly temperature dependent; 4) the beta compliance magnitude decreases by a factor of three upon cooling in the temperature range studied. The final part of the paper briefly presents measurements of the dynamic adiabatic bulk modulus covering frequencies from 10 mHz to 10 kHz in the temperature range 172 K to 200 K. The data are qualitatively similar to the shear data by having a significant beta process. A single-order-parameter framework is suggested to rationalize these similarities

Genotype-informed estimation of risk of coronary heart disease based on genome-wide association data linked to the electronic medical record

<p>Abstract</p> <p>Background</p> <p>Susceptibility variants identified by genome-wide association studies (GWAS) have modest effect sizes. Whether such variants provide incremental information in assessing risk for common 'complex' diseases is unclear. We investigated whether measured and imputed genotypes from a GWAS dataset linked to the electronic medical record alter estimates of coronary heart disease (CHD) risk.</p> <p>Methods</p> <p>Study participants (<it>n </it>= 1243) had no known cardiovascular disease and were considered to be at high, intermediate, or low 10-year risk of CHD based on the Framingham risk score (FRS) which includes age, sex, total and HDL cholesterol, blood pressure, diabetes, and smoking status. Of twelve SNPs identified in prior GWAS to be associated with CHD, four were genotyped in the participants as part of a GWAS. Genotypes for seven SNPs were imputed from HapMap CEU population using the program MACH. We calculated a multiplex genetic risk score for each patient based on the odds ratios of the susceptibility SNPs and incorporated this into the FRS.</p> <p>Results</p> <p>The mean (SD) number of risk alleles was 12.31 (1.95), range 6-18. The mean (SD) of the weighted genetic risk score was 12.64 (2.05), range 5.75-18.20. The CHD genetic risk score was not correlated with the FRS (<it>P </it>= 0.78). After incorporating the genetic risk score into the FRS, a total of 380 individuals (30.6%) were reclassified into higher-(188) or lower-risk groups (192).</p> <p>Conclusion</p> <p>A genetic risk score based on measured/imputed genotypes at 11 susceptibility SNPs, led to significant reclassification in the 10-y CHD risk categories. Additional prospective studies are needed to assess accuracy and clinical utility of such reclassification.</p