scholarly journals Time-resolved charge detection with cross-correlation techniques

2009 ◽  
Vol 79 (3) ◽  
Author(s):  
B. Küng ◽  
O. Pfäffli ◽  
S. Gustavsson ◽  
T. Ihn ◽  
K. Ensslin ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Time Resolved ◽  
Charge Detection ◽  
Correlation Techniques

Assessing Convergence in Predictions of Periodic-Unsteady Flowfields

2006 ◽  
Author(s):  
J. P. Clark ◽  
E. A. Grover
Keyword(s):  
Cross Correlation ◽  
Unsteady Flows ◽  
Digital Signal ◽  
Design Decisions ◽  
Time Resolved ◽  
Design Engineers ◽  
Cross Correlations ◽  
Parseval’S Theorem ◽  
Hot Streak

Predictions of time-resolved flowfields are now commonplace within the gas-turbine industry, and the results of such simulations are often used to make design decisions during the development of new products. Hence it is necessary for design engineers to have a robust method to determine the level of convergence in design predictions. Here we report on a method developed to determine the level of convergence in a predicted flowfield that is characterized by periodic-unsteadiness. The method relies on fundamental concepts from digital signal processing including the discrete Fourier transform, cross-correlation, and Parseval’s theorem. Often in predictions of vane-blade interaction in turbomachines, the period of the unsteady fluctuations is expected. In this method, the development of time-mean quantities. Fourier components (both magnitude and phase), cross-correlations, and integrated signal power are tracked at locations of interest from one period to the next as the solution progresses. Each of these separate quantities yields some relative measure of convergence that is subsequently processed to form a fuzzy set. Thus the overall level of convergence in the solution is given by the intersection of these sets. Examples of the application of this technique to several predictions of unsteady flows from two separate solvers are given. These include a prediction of hot-streak migration as well as more typical cases. It is shown that the method yields a robust determination of convergence. Also, the results of the technique can guide further analysis and/or post-processing of the flowfield. Finally, the method is useful for the detection of inherent unsteadiness in the flowfield, and as such it can be used to prevent design escapes.

Correlation Techniques Applied to Gas Chromatography: A Re-Appraisal

1972 ◽  
Vol 5 (9) ◽  
pp. 351-353 ◽  
Author(s):  
G C Moss ◽  
K R Godfrey
Keyword(s):  
Gas Chromatography ◽  
Environmental Pollution ◽  
Trace Analysis ◽  
Cross Correlation ◽  
Single Sample ◽  
Injection Method ◽  
On Line ◽  
Series Of Experiments ◽  
Correlation Techniques ◽  
Line Cross

The case for applying correlation techniques to gas chromatography has been re-examined following the introduction of on-line cross-correlators, and it is concluded that there is still little scope for these techniques in a normal chromatograph situation. A series of experiments designed to demonstrate the feasibility of applying cross-correlation to trace analysis by gas chromatography is reported and, from these experiments, it is concluded that correlation offers considerable advantages over the conventional single-sample injection method when minute quantities of a component in a sample gas are being sought. With the continuing interest in environmental pollution, there appears to be much scope for correlation techniques in this area.

30. Radial Velocities (Vitesses Radiales)

1988 ◽  
Vol 20 (01) ◽  
pp. 355-362 ◽  
Author(s):  
J. Andersen ◽  
D. W. Latham ◽  
A. Florsch ◽  
E. Maurice ◽  
M. Mayor ◽  
...  
Keyword(s):  
Cross Correlation ◽  
State Of The Art ◽  
Present Report ◽  
Radial Velocities ◽  
Developmental Phase ◽  
Preliminary Results ◽  
Reduction Techniques ◽  
Current State ◽  
Correlation Techniques ◽  
General Adoption

The present report on the activities of IAU Commission 30, covering the triennium June l, 1984 through June 1, 1987, will be somewhat different from its recent predecessors in both content and style. Over the preceding decade or so, the reports mainly emphasized the dramatic improvements in observing efficiency, achieved primarily through the general adoption of cross-correlation techniques, combined with modern detectors attached to either specialized spectrometers or to existing, more conventional instruments. A great surge of observational activity followed, directed towards a variety of astrophysical problems, some of which are of a more classical nature, but many of which are in entirely new classes of research. At the time of the previous reports, most of the major observational projects were still underway, even if some preliminary results were emerging. The proceedings of IAU Colloquium No. 88,Stellar Radial Velocities(L. Davis Press, 1985) contains a collection of papers on instrumentation and reduction techniques as well as on ongoing observing programs which remains a very useful source of references to this developmental phase as well as to the current state of the art.

Cross-Correlation Techniques in Chromatography

1976 ◽  
Vol 14 (6) ◽  
pp. 265-270 ◽  
Author(s):  
R. Annino ◽  
E. Grushka
Keyword(s):  
Cross Correlation ◽  
Correlation Techniques
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