1. A method of obtaining a measure of flow from an electromagnetic flow meter having at least one field generating coil and potential sensing electrodes, the method comprising:
applying, to the at least one field generating coil, a composite excitation waveform comprising at least two frequency components, wherein a plurality of frequency components are simultaneously present for at least a portion of the waveform;
sampling a potential sensed by the potential sensing electrodes to produce a sampled output;
correlating the sampled output with a composite waveform based on the composite excitation waveform; and
deriving a measure of flow based on the result of the correlating.
2. A method according to claim 1, wherein the waveform comprises a set of components, each having a pre-specified amplitude and frequency.
3. A method according to claim 1, wherein the composite waveform is non-sinusoidal.
4. A method according to claim 1, wherein the composite waveform is digitally synthesised.
5. A method according to claim 1, wherein correlation is performed over a window which does not contain an integer number of periods of all frequency components.
6. A method according to claim 5, wherein the window is shorter than the period of the lowest frequency component.
7. A method according to claim 1, wherein correlating comprises determining a measure of closeness of fit.
8. A method according to claim 1, further comprising deriving a factor from said correlating, and deriving a measure of flow from the factor.
9. A method according to claim 1, further comprising determining a measure of a trend within a correlation window.
10. A method according to claim 9, further comprising subtracting the measure of trend from the output sample.
11. A method according to claim 9, further comprising determining a measure of measurement accuracy from the measure of trend.
12. A method according to claim 10, wherein the processing signal is the output of an electromagnetic flow meter.
13. A method according to claim 10, wherein the physical quantity is flow.
14. A method according to claim 10, further comprising determining a measure of a linear trend.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An exhaust trap device for trapping solidified substances from an exhaust gas passing through a gas exhaust route, comprising:
a plurality of exhaust trap sections arranged in series along the exhaust route, each section having an internally formed exhaust path through which the exhaust gas passes,
wherein the plurality of exhaust trap sections includes a first exhaust trap section arranged at an upstream side in a flow direction of the exhaust gas and a second exhaust trap section arranged at a downstream side in the flow direction of the exhaust gas,
wherein the first exhaust trap section is provided with one or more collision plates arranged to interrupt an exhaust gas flow moving along an axis of an exhaust path of the first exhaust trap section, the collision plates being arranged such that a space extending continuously along the axis of the exhaust path without being interrupted by any of the collision plates arranged within the exhaust path exists in the exhaust path, and
wherein the second exhaust trap section is provided with a plural number of collision plates arranged to interrupt an exhaust gas flow moving along an axis of an exhaust path of the second exhaust trap section, the plural number of collision plates being arranged such that a space extending continuously along the axis of the exhaust path without being interrupted by any of the collision plates arranged within the exhaust path does not exist in the exhaust path.
2. The exhaust trap device of claim 1, wherein the plurality of exhaust trap sections are constructed to be connected to and separated from each other.
3. An exhaust trap device for trapping solidified substances from an exhaust gas passing through a gas exhaust route, comprising:
a plurality of exhaust trap sections arranged in series along the exhaust route, each section having an internally formed exhaust path through which the exhaust gas passes,
wherein the plurality of exhaust trap sections includes a first exhaust trap section arranged at an upstream side in a flow direction of the exhaust gas and a second exhaust trap section arranged at a downstream side in the flow direction of the exhaust gas,
wherein each of the first and the second exhaust trap section is provided with one or more collision plates, and
wherein angles that an axis of an exhaust path makes with respect to the collision plates in the second exhaust trap section are greater than angles that an axis of an exhaust path makes with respect to the collision plates in the first exhaust trap section.
4. The exhaust trap device of claim 3, wherein the first and the second exhaust trap section are arranged such that one section is disposed outside the other to surround same and a path inverting portion for inverting the flow direction of the exhaust gas is provided between the first exhaust trap section and the second exhaust trap section.
5. The exhaust trap device of claim 4, wherein the path inverting portion is connected with the entire perimeters of the first exhaust trap section and the second exhaust trap section.
6. The exhaust trap device of claim 1, wherein the collision plates are arranged to allow the exhaust gas to spirally flow within the exhaust path in which the collision plates are arranged.
7. A gas reaction apparatus comprising:
a gas supply unit;
a gas reaction chamber in which gases supplied from the gas supply unit are reacted;
an exhaust route associated with the gas supply unit or the gas reaction chamber; and
the exhaust trap device as recited in claim 1, the exhaust trap device being arranged on the exhaust route.
8. The exhaust trap device of claim 3, wherein the collision plates are arranged to allow the exhaust gas to spirally flow within the exhaust path in which the collision plates are arranged.
9. A gas reaction apparatus comprising:
a gas supply unit;
a gas reaction chamber in which gases supplied from the gas supply unit are reacted;
an exhaust route associated with the gas supply unit or the gas reaction chamber; and
the exhaust trap device as recited in claim 3, the exhaust trap device being arranged on the exhaust route.