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Combined Numerical Analysis of an Oil-free Twin Screw Compressor Using 3D CFD and 1D Multi-chamber Thermodynamic Model
The application of three-dimensional computational fluid dynamics in twin-screw compressors provides an outstanding opportunity for developers to gain an understanding of the complex internal flow phenomena occurring within the machine. Equipped with this knowledge, design parameters, such as clearances and port geometry, can be optimised, to enhance performance. However, as with all modelling, be it numerical or analytical, a high degree of certainty in the accuracy of the results is necessary.
This paper presents the results of a study of oil-free twin screw compressor in which the results of two modelling techniques are compared. The modelling techniques used are an analytical non-dimensional thermodynamic chamber model and a numerical computational fluid dynamic model. The paper presents an overview of an oil-free twin screw compressor machine, before describing important operating characteristics and the modelling techniques used. To validate, both models are compared against historical test data, this validation indicated the chamber model is more accurate. Following this, the focus will be on the comparison of key performance indicators, including, volume flow rate, volumetric efficiency, indicated power, and discharge temperature at varying duty points. The paper concludes that the difference between both models decreases as the compressor operating speed increases, although the level of variance is dependent on pressure ratio
Immunoreactivity for a calmodulin-dependent protein kinase is selectively increased in macaque striate cortex after monocular deprivation
Immunocytochemical methods were used to localize type II Ca2+/calmodulin-dependent protein kinase in the macaque primary visual cortex. Neurons that stain for the kinase include both pyramidal and nonpyramidal cells and they appear to form a subset of cortical neurons. They are densely packed in layers II and IVB, somewhat more sparse in layers III, IVCß, and VI, and nearly absent in layer V. In normal animals the distribution of kinase-positive cells within each layer is relatively uniform. However, in animals in which one eye is removed 7-14 days before sacrifice or sutured shut for 9 or 11 weeks, the cells in layer IVCß are divided into alternating lightly and darkly stained bands. Comparison of immunocytochemically stained sections with adjacent sections stained for the mitochondrial enzyme, cytochrome oxidase, reveals that the kinase staining increases in ocular dominance columns originally driven by the removed or closed eye. These findings suggest that either the concentration of type II Ca2+/calmodulin-dependent protein kinase or its accessibility to the antibody probe increases dramatically and selectively in neurons of macaque primary visual cortex that have been deprived of their normal visual input. This may indicate that changing levels of activity in cortical neurons can alter their regulatory machinery
Effect of a Spin-1/2 Impurity on the Spin-1 Antiferromagnetic Heisenberg Chain
Low-lying excited states as well as the ground state of the spin-1 antiferro-
magnetic Heisenberg chain with a spin-1/2 impurity are investigated by means of
a variational method and a method of numerical diagonalization. It is shown
that 1) the impurity spin brings about massive modes in the Haldane gap, 2)
when the the impurity-host coupling is sufficiently weak, the phenomenological
Hamiltonian used by Hagiwara {\it et al.} in the analysis of ESR experimental
results for NENP containing a small amount of spin-1/2 Cu impurities is
equivalent to a more realistic Hamiltonian, as far as the energies of the
low-lying states are concerned, 3) the results obtained by the variational
method are in semi-quantitatively good agreement with those obtained by the
numerical diagonalization.Comment: 11 pages, plain TeX (Postscript figures are included), KU-CCS-93-00
Theology at the coal-face of hospitalisation - the development and evaluation of a postgraduate certificate in Healthcare Chaplaincy
Healthcare chaplaincy is working towards recognition as a registered health profession. An accredited programme of professional education is part of that process. The University of Glasgow supported by NHS Education for Scotland have developed a programme of professional education for healthcare chaplains that is integrated into an MSc. (MedSci) in healthcare. This article outlines the commissioning, development and evaluation of a postgraduate certificate in healthcare chaplaincy by students, clinical mentors and experienced healthcare chaplains. It also highlights an innovative approach to practice development in spiritual and religious care in healthcare
Planet formation around stars of various masses: Hot super-Earths
We consider trends resulting from two formation mechanisms for short-period
super-Earths: planet-planet scattering and migration. We model scenarios where
these planets originate near the snow line in ``cold finger'' circumstellar
disks. Low-mass planet-planet scattering excites planets to low periastron
orbits only for lower mass stars. With long circularisation times, these
planets reside on long-period eccentric orbits. Closer formation regions mean
planets that reach short-period orbits by migration are most common around
low-mass stars. Above ~1 Solar mass, planets massive enough to migrate to
close-in orbits before the gas disk dissipates are above the critical mass for
gas giant formation. Thus, there is an upper stellar mass limit for
short-period super-Earths that form by migration. If disk masses are
distributed as a power law, planet frequency increases with metallicity because
most disks have low masses. For disk masses distributed around a relatively
high mass, planet frequency decreases with increasing metallicity. As icy
planets migrate, they shepherd interior objects toward the star, which grow to
~1 Earth mass. In contrast to icy migrators, surviving shepherded planets are
rocky. Upon reaching short-period orbits, planets are subject to evaporation
processes. The closest planets may be reduced to rocky or icy cores. Low-mass
stars have lower EUV luminosities, so the level of evaporation decreases with
decreasing stellar mass.Comment: Accepted to ApJ. 13 pages of emulateap
Development of the health and economic consequences of smoking interactive model
Objective-To describe the health and economic consequences of smoking model, a user friendly, web based tool, designed to estimate the health and economic outcomes associated with smoking and the benefits of smoking cessation. Results-An overview of the development of the model equations and user interface is given, and data from the UK are presented as an example of the model outputs. These results show that a typical smoking cessation strategy costs approximately pound 1200 per life year saved and pound 22 000 per death averted. Conclusions-The model successfully captures the complexity required to model smoking behaviour and associated mortality, morbidity, and health care costs. Furthermore, the interface provides the results in a simple and flexible way so as to be useful to a variety of audiences and to simulate a variety of smoking cessation methods
Baseline design of the filters for the LAD detector on board LOFT
The Large Observatory for X-ray Timing (LOFT) was one of the M3 missions
selected for the phase A study in the ESA's Cosmic Vision program. LOFT is
designed to perform high-time-resolution X-ray observations of black holes and
neutron stars. The main instrument on the LOFT payload is the Large Area
Detector (LAD), a collimated experiment with a nominal effective area of ~10 m
2 @ 8 keV, and a spectral resolution of ~240 eV in the energy band 2-30 keV.
These performances are achieved covering a large collecting area with more than
2000 large-area Silicon Drift Detectors (SDDs) each one coupled to a collimator
based on lead-glass micro-channel plates. In order to reduce the thermal load
onto the detectors, which are open to Sky, and to protect them from out of band
radiation, optical-thermal filter will be mounted in front of the SDDs.
Different options have been considered for the LAD filters for best compromise
between high quantum efficiency and high mechanical robustness. We present the
baseline design of the optical-thermal filters, show the nominal performances,
and present preliminary test results performed during the phase A study.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014:
Ultraviolet to Gamma Ray, 91446
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