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Papers by Asle Lygre
Ultrasonics, 1987
Transit-time ultrasonic gas flowmeters offer several advantages compared to other current flowmet... more Transit-time ultrasonic gas flowmeters offer several advantages compared to other current flowmeter technology, and they have the potential of being developed into cost-effective and reliable flowmeters. One important step towards implementing more fully the advantages of ultrasonic flowmeter technology is to apply flowmeter simulation models in the design process. A simulation model which describes the signal transmission for a single acoustic beam in an ultrasonic transit-time flowmeter, is described here. Some of the capabilities of the model in predicting several important effects in the functioning of a flowmeter signal transmission channel are demonstrated for a given simplified set of design parameters.
Journal of Physical Oceanography, 1988
Abstract Wave records obtained by Waverider and heave/pitch/roll data buoys on the Norwegian cont... more Abstract Wave records obtained by Waverider and heave/pitch/roll data buoys on the Norwegian continental shelf have been analysed in order to gain information on spectral characteristics (bandwidth, peak frequency, significant wave height and direction) during severe swell events. The main source of Long period swell is the northwestern Atlantic, and extreme events are caused by intense extratropical cyclones moving rapidly in a northeasterly direction. The data show well energy at periods of 20–25 a and with a maximum significant wave height between 4 and 5 m. By using simple wind and wave models it has been possible to identify different regimes for the evolution of the bandwidth of the well spectrum which also have been confirmed by observations. The model predictions and data analysis lead to a refinement of the classical ridge line analysis in which both the origin time and duration of the storm may be estimated directly from the evolution of the spectrum. In some cases it has also been found that wa...
Fig.1. Planar SOFC STACK operating principle. Oxygen ”diffuses” from the air side (cathode) and r... more Fig.1. Planar SOFC STACK operating principle. Oxygen ”diffuses” from the air side (cathode) and reacts with the fuel, H2 and CO, produced by reforming natural gas. The air exhaust is hot oxygen depleted-air, and the fuel exhaust consists of steam, CO2 and unburned fuel whose respective concentrations depend on the inlet fuel used and on the fuel utilization. Note, the STACK elements are not drawn to scale.
Elsevier Oceanography Series, Dec 31, 1984
Journal of Physical Oceanography, 1986
Ultrasonics, 1987
Transit-time ultrasonic gas flowmeters offer several advantages compared to other current flowmet... more Transit-time ultrasonic gas flowmeters offer several advantages compared to other current flowmeter technology, and they have the potential of being developed into cost-effective and reliable flowmeters. One important step towards implementing more fully the advantages of ultrasonic flowmeter technology is to apply flowmeter simulation models in the design process. A simulation model which describes the signal transmission for a single acoustic beam in an ultrasonic transit-time flowmeter, is described here. Some of the capabilities of the model in predicting several important effects in the functioning of a flowmeter signal transmission channel are demonstrated for a given simplified set of design parameters.
Journal of Physical Oceanography, 1988
Abstract Wave records obtained by Waverider and heave/pitch/roll data buoys on the Norwegian cont... more Abstract Wave records obtained by Waverider and heave/pitch/roll data buoys on the Norwegian continental shelf have been analysed in order to gain information on spectral characteristics (bandwidth, peak frequency, significant wave height and direction) during severe swell events. The main source of Long period swell is the northwestern Atlantic, and extreme events are caused by intense extratropical cyclones moving rapidly in a northeasterly direction. The data show well energy at periods of 20–25 a and with a maximum significant wave height between 4 and 5 m. By using simple wind and wave models it has been possible to identify different regimes for the evolution of the bandwidth of the well spectrum which also have been confirmed by observations. The model predictions and data analysis lead to a refinement of the classical ridge line analysis in which both the origin time and duration of the storm may be estimated directly from the evolution of the spectrum. In some cases it has also been found that wa...
Fig.1. Planar SOFC STACK operating principle. Oxygen ”diffuses” from the air side (cathode) and r... more Fig.1. Planar SOFC STACK operating principle. Oxygen ”diffuses” from the air side (cathode) and reacts with the fuel, H2 and CO, produced by reforming natural gas. The air exhaust is hot oxygen depleted-air, and the fuel exhaust consists of steam, CO2 and unburned fuel whose respective concentrations depend on the inlet fuel used and on the fuel utilization. Note, the STACK elements are not drawn to scale.
Elsevier Oceanography Series, Dec 31, 1984
Journal of Physical Oceanography, 1986