Mission planning for an Earth observation low Earth orbiter: ERS-1

ERS-1, the first European Remote Sensing satellite, has a payload which consists primarily of microwave instruments and is in a polar sun-synchronous orbit. All ground and on-board activities from user requests to delivery of data products are combined into one integrated system. In view of the high number of products which can be generated by ERS-1, the Mission Planning System (MPS), which plans the on-board activities of ERS-1, is an essential tool for operations since manual planning of the large number of daily operations is out of the question. In addition the MPS, in line with the integrated nature of the ERS-1 system, also plans activities at the prime ground station, including among others, the operation of the payload data processing systems there. This paper outlines the operations concepts for ERS-1 mission planning, and describes the Mission Planning System used at the ERS-1 Control Center. Novel functionalities, such as automatic resource clash resolution, are described. A critical discussion gives lessons learned for future mission planning systems

Automated computational cognitive-modeling: goal-specific analysis for large websites

The information architecture of websites is the most important remaining source of usability problems. Therefore, this research explores automated cognitive computational analysis of the information architecture of large websites as a basis for improvement. To support goal-specific analysis, an enhanced model of web navigation was implemented with a novel database-oriented approach. Web navigation was simulated on the information architecture of two large sites. With the improved labeling system of the information architecture, simulation results showed a significant reduction in navigation problems. The results of two experiments demonstrate that sites with improved information architecture result in better outcomes of user information retrieval. Our database-oriented approach is extensible, allowing non-goal-specific analysis, modeling of nontext media content, and analysis of the organization- and navigation systems of information architectures.</jats:p

The Scottish economy [December 1995]

This section presents short and long term forecasts for the quarterly growth rates of Scottish manufacturing (Division D of the 1992 SIC) output

The Scottish economy [September 1995]

This section presents short and long term forecasts for the quarterly growth rates of Scottish manufacturing (Division D of the 1992 SIC) output

An experimental investigation into DEF dosing strategies for heavy duty vehicle applications

Copyright © 2015 SAE International.In recent years urea selective catalytic reduction (SCR) has become the principal method of NOx abatement within heavy duty (HD) diesel exhaust systems; however, with upcoming applications demanding NOx reduction efficiencies of above 96 % on engines producing upwards of 10 g·kWh−1 NOx, future diesel exhaust fluid (DEF) dosing systems will be required to operate stably at significantly increased dosing rates. Developing a dosing system capable of meeting the increased performance requirements demands an improved understanding of how DEF sprays interact with changing exhaust flows. This study has investigated four production systems representing a diverse range of dosing strategies in order to determine how performance is influenced by spray structure and identify promising strategies for further development. The construction of an optically accessible hot-air flow rig has enabled visualisation of DEF injection into flows representative of HD diesel exhaust conditions. High-speed and laser sheet imaging have been applied to capture the injection event and analyse spray development within the flows. Results from ambient shadowgraphy show the extent of variation in spray structure that exists between the systems; further quantified with droplet size distribution data collected using phase Doppler interferometry (PDI). Imaging within the exhaust section indicates that the structure of a spray has a significant impact on droplet entrainment within the flow, in turn affecting the level of spray-wall impingement seen. This suggests knowledge of dosing strategy will be critical for optimal system design and enabling near future dosing rate demands to be met

Optical investigation on the ability of a cordierite substrate mixing device to combat deposits in SCR dosing systems

Selective catalytic reduction (SCR) has become the mainstream approach for removing heavy-duty (HD) diesel engine NOx emissions. Highly efficient SCR systems are a key enabling technology allowing engines to be calibrated for very high NOx output with a resultant gain in fuel consumption while still maintaining NOx emissions compliance. One key to the successful implementation of high efficiency SCR at elevated engine out NOx levels is the ability to introduce significantly more AdBlue into the exhaust flow while still ensuring complete ammonia production and avoiding the formation of deposits. This paper presents a body of experimental work conducted on an exhaust test bench using optical techniques including high-speed imaging and phase Doppler interferometry (PDI), applied under representative exhaust conditions to a HD diesel engine after-treatment system with optical access inside the mixer tube. Two different sprays were used to dose AdBlue onto the mixing device. A three-hole injector and a single-hole pressure-swirl injector were characterised in ambient and heated exhaust flow conditions. A metallic two-stage mixer and an uncoated cordierite ceramic substrate mixer were compared and demonstrated the ability of the substrate mixer to reduce deposit formation at higher dosing rates inside the mixer tube when used with the correct spray type. High-speed imaging revealed the ability of the substrate to absorb injected AdBlue spray at cooler exhaust temperatures. However, using the incorrect spray can lead to liquid saturation inside the substrate channels, which is detrimental due to the formation of deposits on the rear face of the substrate

The Scottish economy [December 1995]

This section presents short and long term forecasts for the quarterly growth rates of Scottish manufacturing (Division D of the 1992 SIC) output

The Scottish economy [September 1989]

[Abstract unavailable