Improvement of measurement accuracy in SU(1,1) interferometers

We consider an SU(1,1) interferometer employing four-wave mixers that is fed with two-mode states which are both coherent and intelligent states of the SU(1,1) Lie group. It is shown that the phase sensitivity of the interferometer can be essentially improved by using input states with a large photon-number difference between the modes.Comment: LaTeX, 5 pages, 1 figure (compressed PostScript, available at http://www.technion.ac.il/~brif/graphics/interfer_graph/qopt.ps.gz ). More information on http://www.technion.ac.il/~brif/science.htm

Efficient fiber Bragg grating and fiber Fabry-Pe'rot sensor multiplexing scheme using a broadband pulsed mode-locked laser

A pulsed broadband mode-locked laser (MLL) combined with interferometric interrogation is shown to yield an efficient means of multiplexing a large number of fiber Bragg grating (FBG) or fiber Fabry-Perot (FFP) strain sensors with high performance. System configurations utilizing time division multiplexing (TDM) permit high resolution, accuracy, and bandwidth strain measurements along with high sensor densities. Strain resolutions of 23-60 n epsilon/Hz(1/2) at frequencies up to 800 Hz (expandable to 139 kHz) and a differential strain-measurement accuracy of +/- 1 mu epsilon are demonstrated. Interrogation of a low-finesse FFP sensor is also demonstrated, from which a strain resolution of 2 n epsilon/Hz(1/2) and strain-measurement accuracy of +/- 31 n epsilon are achieved. The system has the capability of interrogating well in excess of 50 sensors per fiber depending on crosstalk requirements. A discussion on sensor spacing, bandwidth, dynamic range, and measurement accuracy is also given

Modelling and measurement accuracy enhancement of flue gas flow using neural networks

This paper discusses the modeling of the flue gas flow in industrial ducts and stacks using artificial neural networks (ANN's). Based upon the individual velocity and other operating conditions, an ANN model has been developed for the measurement of the volume flow rate. The model has been validated by the experiment using a case-study power plant. The results have shown that the model can largely compensate for the nonrepresentativeness of a sampling location and, as a result, the measurement accuracy of the flue gas flow can be significantly improved

Digital data averager improves conventional measurement system performance

Multipurpose digital averager provides measurement improvement in noisy signal environments. It provides increased measurement accuracy and resolution to basic instrumentation devices by an arithmetical process in real time. It is used with standard conventional measurement equipment and digital data printers