Seti Figure of Merit

International Astronomical Union Colloquium ◽

10.1017/s0252921100015293 ◽

1997 ◽

Vol 161 ◽

pp. 711-717 ◽

Cited By ~ 1

Author(s):

John W. Dreher ◽

D. Kent Cullers

Keyword(s):

Figure Of Merit ◽

Qualitative Difference ◽

Current Generation ◽

Detection Range ◽

Sky Surveys ◽

Independent Observations ◽

Good For

AbstractWe develop a figure of merit for SETI observations which is anexplicitfunction of the EIRP of the transmitters, which allows us to treat sky surveys and targeted searches on the same footing. For each EIRP, we calculate the product of terms measuring the number of stars within detection range, the range of frequencies searched, and the number of independent observations for each star. For a given set of SETI observations, the result is a graph of merit versus transmitter EIRP. We apply this technique to several completed and ongoing SETI programs. The results provide a quantitative confirmation of the expected qualitative difference between sky surveys and targeted searches: the Project Phoenix targeted search is good for finding transmitters in the 109to 1014W range, while the sky surveys do their best at higher powers. Current generation optical SETI is not yet competitive with microwave SETI.

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Statistical Analysis of Sonar Performance Prediction in Littoral Environments

Journal of Mechanics ◽

10.1017/s1727719100004457 ◽

2006 ◽

Vol 22 (2) ◽

pp. 155-160 ◽

Cited By ~ 1

Author(s):

C.-W. Wang ◽

M.-C. Yuan ◽

C.-R. Yang ◽

Y.-Y. Chang ◽

C.-F. Chen

Keyword(s):

Statistical Analysis ◽

Standard Deviation ◽

Performance Prediction ◽

Figure Of Merit ◽

Ambient Noise ◽

Transmission Loss ◽

Ocean Water ◽

Detection Range ◽

Passive Sonar ◽

Ocean Environment

AbstractThis paper presents the Statistical Analysis of Passive Sonar Performance Prediction in Littoral Environments. Passive sonar performance and acoustic prediction mainly refer to the detection range. The inputs for estimating the sonar detection range include the Figure of Merit (FOM), Transmission Loss (TL), and Ambient Noise (NL) of the operation region. These inputs are directly related to the ocean environment; hence, the detection range is, too. A littoral environment is highly variable both in time and space. This paper proposes a methodology for analyzing the statistical properties of the detection range from measurements of ocean water column properties. It is found that the detection range of the southwestern region of Taiwan in the summer is 13.8km with 5.9km as the standard deviation and in the winter is 37.8km with 33.6km as the standard deviation.

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Structured Back Focal Plane Interferometry (SBFPI)

Scientific Reports ◽

10.1038/s41598-019-56199-z ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Avinash Upadhya ◽

Yujie Zheng ◽

Li Li ◽

Woei Ming Lee

Keyword(s):

Focal Plane ◽

High Speed ◽

Figure Of Merit ◽

Detection Sensitivity ◽

Low Loss ◽

Optical Aberrations ◽

Detection Range ◽

Linear Detection ◽

Tracking Range ◽

Nanometer Particle

AbstractBack focal plane interferometry (BFPI) is one of the most straightforward and powerful methods for achieving sub-nanometer particle tracking precision at high speed (MHz). BFPI faces technical challenges that prohibit tunable expansion of linear detection range with minimal loss to sensitivity, while maintaining robustness against optical aberrations. In this paper, we devise a tunable BFPI combining a structured beam (conical wavefront) and structured detection (annular quadrant photodiode). This technique, which we termed Structured Back Focal Plane Interferometry (SBFPI), possesses three key novelties namely: extended tracking range, low loss in sensitivity, and resilience to spatial aberrations. Most importantly, the conical wavefront beam preserves the axial Gouy phase shift and lateral beam waist that can then be harnessed in a conventional BFPI system. Through a series of experimental results, we were able to tune detection sensitivity and detection range over the SBFPI parameter space. We also identified a figure of merit based on the experimental optimum that allows us to identify optimal SBPFI configurations that balance both range and sensitivity. In addition, we also studied the resilience of SBFPI against asymmetric spatial aberrations (astigmatism of up to 0.8 λ) along the lateral directions. The simplicity and elegance of SBFPI will accelerate its dissemination to many associated fields in optical detection, interferometry and force spectroscopy.

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Advances in powder diffraction pattern indexing:N-TREOR09

Journal of Applied Crystallography ◽

10.1107/s0021889809025503 ◽

2009 ◽

Vol 42 (5) ◽

pp. 768-775 ◽

Cited By ~ 71

Author(s):

Angela Altomare ◽

Gaetano Campi ◽

Corrado Cuocci ◽

Lars Eriksson ◽

Carmelo Giacovazzo ◽

...

Keyword(s):

Figure Of Merit ◽

Computing Time ◽

Unit Cell ◽

Large Set ◽

Figures Of Merit ◽

Triclinic System ◽

Theoretical Approaches ◽

Unit Cells ◽

Independent Observations ◽

Degree Of Overlap

Powder pattern indexing can still be a challenge, despite the great recent advances in theoretical approaches, computer speed and experimental devices. More plausible unit cells, belonging to different crystal systems, are frequently found by the indexing programs, and recognition of the correct one may not be trivial. The task is, however, of extreme importance: in case of failure a lot of effort and computing time may be wasted. The classical figures of merit for estimating the unit-cell reliability {i.e.M20[de Wolff (1968).J. Appl. Cryst.1, 108–113] andFN[Smith & Snyder (1979).J. Appl. Cryst.12, 60–65]} sometimes fail. For this reason, a new figure of merit has been introduced inN-TREOR09, the updated version of the indexing packageN-TREOR[Altomare, Giacovazzo, Guagliardi, Moliterni, Rizzi & Werner (2000).J. Appl. Cryst.33, 1180–1186], combining the information supplied byM20with additional parameters such as the number of unindexed lines, the degree of overlap in the pattern (the so-called number of statistically independent observations), the symmetry deriving from the automatic evaluation of the extinction group, and the agreement between the calculated and observed profiles. The use of the new parameters requires a dramatic modification of the procedures used worldwide: in the approach presented here, extinction symbol and unit-cell determination are simultaneously estimated.N-TREOR09benefits also from an improved indexing procedure in the triclinic system and has been integrated intoEXPO2009, the updated version ofEXPO2004[Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004).J. Appl. Cryst.37, 1025–1028]. The application of the new procedure to a large set of test structures is described.

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