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Dominant Parameter (dominant + parameter)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

A systematic study of low-mass X-ray binaries in the M31 globular cluster system

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010
Mark B. Peacock
ABSTRACT We investigate low-mass X-ray binaries (LMXBs) in the M31 globular cluster (GC) system using data from the 2XMMi catalogue. These X-ray data are based on all publicly available XMM,Newton observations of the galaxy. This new survey provides the most complete and homogeneous X-ray survey of M31's GCs to date, covering >80 per cent of the confirmed old clusters in the galaxy. We associate 41 X-ray sources with confirmed old clusters in the recent M31 cluster catalogue of Peacock et al. Comparing these data with previous surveys of M31, it is found that three of these clusters are newly identified, including a bright transient source in the cluster B128. Four additional clusters, that are not detected in these 2XMMi data, have previously been associated with X-ray sources from Chandra or ROSAT observations. Including these clusters, we identify 45 clusters in M31 which are associated with X-ray emission. By considering the latest optical GC catalogues, we identify that three of the previously proposed X-ray clusters are likely to be background galaxies and two have stellar profiles. We consider the properties of LMXB hosting clusters and confirm significant trends between the presence of an LMXB and the metallicity, luminosity and stellar collision rate of a cluster. We consider the relationship between the luminosity and stellar collision rate of a cluster and note that LMXB hosting clusters have higher than average stellar collision rates for their mass. Our findings strongly suggest that the stellar collision rate is the dominant parameter related to the presence of LMXBs. This is consistent with the formation of LMXBs in GCs through dynamical interactions. [source]

NOx emissions of an opposed wall-fired pulverized coal utility boiler

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010
Xiaotao Gao
Abstract The present paper was addressed to the effects of operational variables and coal properties on NOx emission level of a 600-MW opposed wall-fired pulverized coal utility boiler. The in situ experiments were performed to study the effects of operational variables on boiler performance by changing individual variables while the other variables were held nearly constant on the basis of the nominal load operation. It was found that the oxygen level was a significant parameter to affect the NOx emission. The impacts of coal properties on NOx emission indicated that NOx emission level decreased with the increase of the ratio of the nitrogen content to low heating value because the volatile matter content in coal significantly influenced the in-flame NOx formation. Coal volatile content was the dominant parameter to affect fuel NOx formation through affecting the reducing condition in the inner near-burner zone when the low NOx burners were applied in the boiler. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Parametric analysis of a coal based combined cycle power plant

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2006
T. Srinivas
Abstract In the present paper thermodynamic analyses, i.e. both energy and exergy analyses have been conducted for a coal based combined cycle power plant, which consists of pressurized circulating fluidized bed (PCFB) partial gasification unit and an atmospheric circulating fluidized bed (ACFB) char combustion unit. Dual pressure steam cycle is considered for the bottoming cycle to reduce irreversibilities during heat transfer from gas to water/steam. The effect of operating variables such as pressure ratio, gas turbine inlet temperature on the performance of combined cycle power plant has been investigated. The pressure ratio and maximum temperature (gas turbine inlet temperature) are identified as the dominant parameters having impact on the combined cycle plant performance. The work output of the topping cycle is found to increase with pressure ratio, while for the bottoming cycle it decreases. However, for the same gas turbine inlet temperature the overall work output of the combined cycle plant increases up to a certain pressure ratio, and thereafter not much increase is observed. The entropy generation, the irreversibilities in each component of the combined cycle and the exergy destruction/losses are also estimated. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Anomalous energy losses for light projectiles traversing a polyvinylformyl resin,

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4-5 2001
L. E. Porter
Abstract Measurements of the stopping powers of the polyvinylformyl resin known as formvar for 0.67,1.75 MeV protons, 1.19,3.02 MeV alpha particles, and 3.9,10.4 MeV 7Li ions have been analyzed in terms of modified Bethe,Bloch theory for the purpose of extracting values of the dominant parameters of the formalism employed. These parameters are the target mean excitation energy and the Barkas-effect parameter, plus a single effective-charge parameter to characterize the interactions of 4He and 7Li projectiles with the target. Whereas results for the Barkas-effect parameter agreed well with the expected value of 1.4±0.1, results for the mean excitation energy lay about 20% below the value of 71.9 eV based on the assumption of linear additivity of stopping effects. Speculation as to the source of this difference is offered. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 [source]