Understanding the relationship between ignition delay and burn duration in a constant volume vessel at diesel engine conditions

Experiments were performed in a constant volume vessel, with fuel sprays injected into the vessel at various different pressure and temperature conditions chosen to represent diesel engine operation at various loads. A range of diesel primary reference fuels (i.e. mixtures of cetane and heptamethylnonane) of varying cetane number (CN) were tested, and as expected lower CN fuels have longer ignition delays. Burn period was plotted against ignition delay and two distinct trends can be seen: “mainly diffusion” diesel combustion in which burn period decreases with ignition delay and “mainly pre-mixed” diesel combustion in which burn period increases with ignition delay. There is typically a minimum in plots of burn period versus ignition delay which represents the transition between the two types of combustion mode. Higher CN, higher engine load and higher boost pressure would seem to favour “mainly diffusion” combustion whilst lower CN, lower loads and non boosted conditions favour “mainly pre-mixed” combustion

Possible symmetries of the superconducting order parameter in a hexagonal ferromagnet

We study the order parameter symmetry in a hexagonal crystal with co-existing superconductivity and ferromagnetism. An experimental example is provided by carbon-based materials, such as graphite-sulfur composites, in which an evidence of such co-existence has been recently discovered. The presence of a non-zero magnetization in the normal phase brings about considerable changes in the symmetry classification of superconducting states, compared to the non-magnetic case.Comment: 4 pages, REVTe

Comments on ‘Linke and Unsworth‐Monteith turbidity parameters in Athens’ by H. D. Kambezidis, D. H. Founda and N. S. Papanikolaou (January B, 1993, 119, 367‐374)

The Notes and correspondence section of this Journal recently contained an article by Kambezidis et al. in which there is a quotation from a paper by Bais et al. saying that the total ozone over Greece during the period 1982‐88 shows a slight increase. This is in contradiction to our recent findings which show that for the period in question, using both ground data and satellite data, there has been a mean annual decrease of total ozone over Greece of about 0.5% per annum; a result that is consistent with the existing literature since 1991. Copyright © 1994 Royal Meteorological Societ

Satellite systems for atmospheric ozone observations

A review of the satellite-borne instrumentation used for the total ozone and ozone vertical profile watch is presented. The principle of the observational method for the monitoring of the atmospheric ozone content is used to group the basic satellite systems. Along these lines the direct-absorption, scattering, and emission-measuring instruments are presented, besides providing a short discussion on the spatio-temporal variability of the ozone content mainly derived from a few outstanding field campaigns. © 2014, Taylor & Francis

The contribution of remote sensing to the implementation of the Montreal Protocol and the monitoring of its success

This paper presents the background to the special issue of the International Journal of Remote Sensing which is being published to celebrate the 20th anniversary of the coming into effect in January 1989 of the Montreal Protocol on substances that damage the amospheric ozone layer. Starting from the discovery of ozone and the ozone layer, we recall the proposition of Molina and Rowland that man-made CFCs pose a major threat to the ozone layer. This was followed by about 15 years of scientific research, scientific discussion, intense political discussions and international negotiations which led to the formulation of the Montreal Protocol that prohibits the manufacture and use of ozone-destroying substances. The papers in this special issue of the Journal are concerned with addressing the role of remote sensing in monitoring and assessing the success, or otherwise, of the Montreal Protocol. © 2009 Taylor & Francis

New aspects of global climate-dynamics research and remote sensing

This paper presents a few of the research tools of modern physics that can successfully be used to achieve a better understanding of the temporal and spatial variability of the multi-component climate system. The observations obtained by the available remotely sensed instrumentation have led to new advances in climate science, which in conjunction with those reported in the IPCC Fourth Assessment Report constitute the background of the existing knowledge on this subject and are discussed in the present special issue. There is some discussion of matters arising since the IPCC Fourth Assessment Report was published. This paper provides the general background to the papers in this special issue of the journal on remote sensing and climate change. © 2011 Taylor & Francis

Ozone depletion over scotland as derived from nimbus-7 TOMS measurements

The TOMS (Total Ozone Mapping Spectrometer) flown on the Nimbus-7 satellite has been measuring the total ozone concentration over the globe since November 1978. Recent investigations based on TOMS data have shown that in the latitude belt 40-70° N the spring ozone depletion rate reaches the value of -0-8 per cent per year. This paper reports trends derived from the TOMS reprocessed total ozone data for the case of Dundee (56-5° N, 3° W) from January 1979 to January 1992. The depletion rate of the mean monthly total ozone concentration over this 13-year period shows a strong variation from more than -15 per cent in December and January to about +0-5 per cent in February and June, while the overall mean is about -7 per cent. © Taylor & Francis Group, LLC

Temporal variations of the total ozone content over greece as deduced from satellite observations

The observations with the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus-7 satellite have previously been used to assess the trends of the total ozone content over Athens, Greece (38°N, 24°E), since 1978, for various months. In the present paper we report some new calculations in which we have taken steps to exclude the effects of biennial and tri-annual oscillations from the trend analysis. The results show that the natural fluctuations of the total ozone content due to these oscillations have little effect on the calculated total ozone depletion trend, over a 13-year period, compared with the strong variations of the total ozone depletion trend from month to month due to other causes. © 1995, Taylor & Francis Group, LLC. All rights reserved