617 research outputs found
What Role, If Any, Will The United Nations Play In The Maintenance Of International Peace And Security Over The Next Fifty Years?
After two years of close observation of the United Nations struggling to answer the challenge of Article 7 of its Charter to maintain international peace and security, I have become an optimist on the question of the United Nations\u27 future, if nonetheless a cautious, realistic one. Whether the United Nations will have such a role, however, depends on the collective ability of the international community to learn from the past fifty years of the organizatio
Sea surface temperature in global analyses: gains from the copernicus imaging microwave radiometer
Sea surface temperatures (SSTs) derived from passive microwave (PMW) observations
benefit global ocean and SST analyses because of their near-all-weather availability. Present PMW
SSTs have a real aperture-limited spatial resolution in excess of 50 km, limiting the spatial fidelity
with which SST features, reflecting ocean dynamics, can be captured. This contrasts with the target
resolution of global analyses of 5 to 10 km. The Copernicus Imaging Microwave Radiometer (CIMR)
is a mission concept under consideration as a high-priority candidate mission for the expansion of
the Copernicus space programme. This instrument would be capable of real aperture resolution
< 15 km with low total uncertainties in the range 0.4–0.8 K for channels between 1.4 and 36.5 GHz,
and a dual-view arrangement that further reduces noise. This paper provides a comparative study
of SST uncertainty and feature resolution with and without the availability of CIMR in the future
SST-observing satellite constellation based on a detailed simulation of CIMR plus infrared observations
and the processing of global SST analyses with 0.05◦ final grid resolution. Simulations of CIMR data
including structured errors were added to an observing system consisting of the Sea and Land Surface
Temperature Radiometer (SLSTR) on Sentinel-3A and the Advanced Very High Resolution Radiometer
(AVHRR) on MetOp-A. This resulted in a large improvement in the global root-mean-square error
(RMSE) for SST from 0.37 K to 0.21 K for January and 0.40 K to 0.25 K for July. There was a particularly
noticeable improvement in the performance of the analysis, as measured by the reduction in RMSE,
for dynamical and persistently cloudy areas. Of these, the Aghulas Current showed an improvement
of 43% in January and 48% in July, the Gulf Stream showed 70% and 44% improvements, the Southern
Ocean showed 57% and 74% improvements, and the Maritime Continent showed 50% and 40% improvements, respectively
Transient and steady-state performance of a single turbojet combustor with four different fuel nozzles
Acceleration and steady-state performance of a tubular combustor was evaluated at two simulated altitudes with four different fuel nozzles. Temperature response lag was observed with all the nozzles. Except for rich-limit blowout, the only combustion failures observed during acceleration were with a fuel nozzle that gave an interrupted flow delivery during the acceleration. This same nozzle, because of superior fuel atomization, gave the highest steady-state combustion efficiencies
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High performance software framework for the calculation of satellite-to-satellite data matchups (MMS version 1.2)
We present a Multisensor Matchup System (MMS) that allows systematic detection of satellite based sensor-to-
sensor matchups and the extraction of local subsets of satellite data around matchup locations. The software system implements a generic matchup-detection approach and is currently being used for validation and sensor harmonisation purposes. An overview of the flexible and highly configurable software architecture and the target processing environments is given. We discuss improvements implemented with respect to heritage systems, and present some performance comparisons. A detailed
description of the intersection algorithm is given which allows a fast matchup detection in geometry and time
Using patterns in the automatic marking of ER-Diagrams
This paper illustrates how the notion of pattern can be used in the automatic analysis and synthesis of diagrams, applied particularly to the automatic marking of ER-diagrams. The paper describes how diagram patterns fit into a general framework for diagram interpretation and provides examples of how patterns can be exploited in other fields. Diagram patterns are defined and specified within the area of ER-diagrams. The paper also shows how patterns are being exploited in a revision tool for understanding ER-diagrams
Experiments in the automatic marking of ER-Diagrams
In this paper we present an approach to the computer understanding of diagrams and show how it can be successfully applied to the automatic marking (grading) of student attempts at drawing entity-relationship (ER) diagrams. The automatic marker has been incorporated into a revision tool to enable students to practice diagramming and obtain feedback on their attempts
On the calculation of air-sea fluxes of CO2 in the presence of temperature and salinity gradients
The presence of vertical temperature and salinity gradients in the upper ocean and the occur- rence of variations in temperature and salinity on time scales from hours to many years complicate the calculation of the flux of carbon dioxide (CO2) across the sea surface. Temperature and salinity affect the interfacial concentration of aqueous CO2 primarily through their effect on solubility with lesser effects related to saturated vapor pressure and the relationship between fugacity and partial pressure. The effects of temperature and salinity profiles in the water column and changes in the aqueous concentration act primarily through the partitioning of the carbonate system. Climatological calculations of flux require atten- tion to variability in the upper ocean and to the limited validity of assuming ‘‘constant chemistry’’ in trans- forming measurements to climatological values. Contrary to some recent analysis, it is shown that the effect on CO2 fluxes of a cool skin on the sea surface is large and ubiquitous. An opposing effect on calculated fluxes is related to the occurrence of warm layers near the surface; this effect can be locally large but will usually coincide with periods of low exchange. A salty skin and salinity anomalies in the upper ocean also affect CO2 flux calculations, though these haline effects are generally weaker than the thermal effects
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