917 research outputs found
Baseline performance and emissions data for a single-cylinder, direct-injected diesel engine
Comprehensive fuel consumption, mean effective cylinder pressure, and emission test results for a supercharged, single-cylinder, direct-injected, four-stroke-cycle, diesel test engine are documented. Inlet air-to-exhaust pressure ratios were varied from 1.25 to 3.35 in order to establish the potential effects of turbocharging techniques on engine performance. Inlet air temperatures and pressures were adjusted from 34 to 107 C and from 193 to 414 kPa to determine the effects on engine performance and emissions. Engine output ranged from 300 to 2100 kPa (brake mean effective pressure) in the speed range of 1000 to 3000 rpm. Gaseous and particulate emission rates were measured. Real-time values of engine friction and pumping loop losses were measured independently and compared with motored engine values
Production of 21 Ne in depth-profiled olivine from a 54 Ma basalt sequence, Eastern Highlands (37° S), Australia
In this study we investigate the cosmogenic neon component in olivine samples from a vertical profile in order to quantify muogenic 21Ne production in this mineral. Samples were collected from an 11 m thick Eocene basalt profile in the Eastern Highlands of southeastern Australia. An eruption age of 54.15 ± 0.36 Ma (2σ) was determined from 40Ar/39Ar step-heating experiments (n = 6) on three whole-rock samples. A 36Cl profile on the section indicated an apparent steady state erosion rate of 4.7 ± 0.5 m Ma−1. The eruption age was used to calculate in situ produced radiogenic 4He and nucleogenic 3He and 21Ne concentrations in olivine. Olivine mineral separates (n = 4), extracted from the upper two metres of the studied profile, reveal cosmogenic 21Ne concentrations that attenuate exponentially with depth. However, olivine (Fo68) extracted from below 2 m does not contain discernible 21Ne aside from magmatic and nucleogenic components, with the exception of one sample that apparently contained equal proportions of nucleogenic and muogenic neon. Modelling results suggest a muogenic neon sea-level high-latitude production rate of 0.02 ± 0.04 to 0.9 ± 1.3 atoms g−1 a−1 (1σ), or <2.5% of spallogenic cosmogenic 21Ne production at Earth’s surface. These data support a key implicit assumption in the literature that accumulation of muogenic 21Ne in olivine in surface samples is likely to be negligible/minimal compared to spallogenic 21Ne
The construction and evaluation of tests to determine the ability of fifth and sixth grade pupils to select relevant materials in the social studies
Thesis (M.A.)--Boston Universit
A declining major merger fraction with redshift in the local Universe from the largest-yet catalog of major and minor mergers in SDSS
It is difficult to accurately identify galaxy mergers and it is an even
larger challenge to classify them by their mass ratio or merger stage. In
previous work we used a suite of simulated mergers to create a classification
technique that uses linear discriminant analysis (LDA) to identify major and
minor mergers. Here, we apply this technique to 1.3 million galaxies from the
SDSS DR16 photometric catalog and present the probability that each galaxy is a
major or minor merger, splitting the classifications by merger stages (early,
late, post-coalescence). We present publicly-available imaging predictor values
and all of the above classifications for one of the largest-yet samples of
galaxies. We measure the major and minor merger fraction ()
and build a mass-complete sample of galaxies, which we bin as a function of
stellar mass and redshift. For the major mergers, we find a positive slope of
with stellar mass and negative slope of
with redshift between stellar masses of
and redshifts of . We are able to reproduce an artificial
positive slope of the major merger fraction with redshift when we do not bin
for mass or craft a complete sample, demonstrating the importance of mass
completeness and mass binning. We determine that the positive trend of the
major merger fraction with stellar mass is consistent with a hierarchical
assembly scenario. The negative trend with redshift requires that an additional
assembly mechanism, such as baryonic feedback, dominates in the local Universe.Comment: 29 pages, 22 figures, see figures 16 and 17 for a summary of the
findings, accepted to MNRA
Random and Correlated Phases of Primordial Gravitaional Waves
The phases of primordial gravity waves is analysed in detail within a quantum
mechanical context following the formalism developed by Grishchuk and Sidorov.
It is found that for physically relevant wavelengths both the phase of each
individual mode and the phase {\it difference} between modes are randomly
distributed. The phase {\it sum} between modes with oppositely directed
wave-vectors, however, is not random and takes on a definite value with no rms
fluctuation. The conventional point of view that primordial gravity waves
appear after inflation as a classical, random stochastic background is also
addressed.Comment: 14 pages, written in REVTE
Interleukin-6 Is a Risk Factor for Atrial Fibrillation in Chronic Kidney Disease: Findings from the CRIC Study.
Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with chronic kidney disease (CKD). In this study, we examined the association between inflammation and AF in 3,762 adults with CKD, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. AF was determined at baseline by self-report and electrocardiogram (ECG). Plasma concentrations of interleukin(IL)-1, IL-1 Receptor antagonist, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor-β, high sensitivity C-Reactive protein, and fibrinogen, measured at baseline. At baseline, 642 subjects had history of AF, but only 44 had AF in ECG recording. During a mean follow-up of 3.7 years, 108 subjects developed new-onset AF. There was no significant association between inflammatory biomarkers and past history of AF. After adjustment for demographic characteristics, comorbid conditions, laboratory values, echocardiographic variables, and medication use, plasma IL-6 level was significantly associated with presence of AF at baseline (Odds ratio [OR], 1.61; 95% confidence interval [CI], 1.21 to 2.14; P = 0.001) and new-onset AF (OR, 1.25; 95% CI, 1.02 to 1.53; P = 0.03). To summarize, plasma IL-6 level is an independent and consistent predictor of AF in patients with CKD
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