Standard deviation of averaged digital time interval measurements

1980 ◽  
Vol 51 (10) ◽  
pp. 1423-1424 ◽  
Author(s):  
Georg A. Reider
Keyword(s):  
Standard Deviation ◽  
Time Interval ◽  
Digital Time

scholarly journals Identification of Precursory Anomalies before Moderate-strong Earthquakes in Junction of Shanxi-Hebei-Inner Mongolia Area

2020 ◽  
Vol 206 ◽  
pp. 01011
Author(s):  
Li Hong
Keyword(s):  
Standard Deviation ◽  
Inner Mongolia ◽  
Strong Earthquake ◽  
Earthquake Magnitude ◽  
Parameter Analysis ◽  
Time Interval ◽  
Study Region ◽  
Strong Earthquakes ◽  
Spectrum Method ◽  
Prediction Efficiency

In this paper, we take the Junction of Shanxi-Hebei-Inner Mongolia area as study region using earthquake corresponding relevancy spectrum method (ECRS method) to identify comprehensive precursory anomalies before moderate-strong earthquake. On base of single-parameter relevancy spectrum database with target earthquake magnitude as Ms4.7 and initial earthquake magnitude as Ms1, we carry on multi-parameter analysis and find that result with time interval of 9 months and anomaly threshold with 0.40 times standard deviation has better prediction efficiency. Its anomaly corresponding rate and earthquake corresponding rate are 6/10 and 9/9 respectively.

A high-resolution digital time-interval measurement instrument

Measurement ◽  
1997 ◽  
Vol 22 (3-4) ◽  
pp. 129-140 ◽  
Author(s):  
Domenico Mirri ◽  
Gaetano Pasini ◽  
Gaetano Iuculano ◽  
Fabio Filicori ◽  
Gabriella Pellegrini ◽  
...  
Keyword(s):  
High Resolution ◽  
Measurement Instrument ◽  
Time Interval ◽  
Interval Measurement ◽  
Time Interval Measurement ◽  
Digital Time

The caesium resonator as a standard of frequency and time

1957 ◽  
Vol 250 (973) ◽  
pp. 45-69 ◽  
Keyword(s):  
Standard Deviation ◽  
Transition Region ◽  
Central Line ◽  
International Committee ◽  
Geometrical Parameters ◽  
Time Interval ◽  
Atomic Unit ◽  
Exciting Field ◽  
Weights And Measures ◽  
Astronomical Time

The construction, operation, and testing of the standard are described. The resonance employed is that due to the hyperfine splitting of caesium, having a frequency of approximately 9192 Mc/s. The transitions between the two atomic states F, m f (4,0) and F, m F (3, 0) are detected in an atomic-beam chamber, in which the length of the transition region is 47 cm, giving a width of resonance, at half deflexion, of 350 cycles, and a standard deviation of setting to the peak of the resonance of ± l c/s . It is shown that the geometrical parameters of the beam chamber such as slit widths, alinement of the beam, and shape of the pole-pieces of the deflecting magnets are relatively unimportant, and that other parameters, including the pressure in the beam chamber, the temperature of the oven, from which the caesium atoms are evaporated, and the radio-frequency power exciting the transitions can be varied throughout wide limits without causing changes in resonant frequency exceeding 1 part in 10 10 . A unidirectional magnetic field is applied over the transition region to remove the field-dependent resonant lines of the Zeeman pattern from the central line which depends on the field to only a second-order extent. It has been found that a satisfactory resonance is obtained with a field as low as 0.05 Oe at which the total effect of the field on the frequency is only 1 c/s. The dependence of the frequency on the phase conditions in the two-cavity resonators carrying the exciting field is studied, and it is concluded that the phases can be made sufficiently close to enable the frequency to be defined with a precision of ± 1 part in 10 10 . The resonator is used as a passive instrument to calibrate the quartz clocks, usually at intervals of a few days; and it is estimated that the clocks calibrated in this way provide at all times the atomic unit of frequency and time interval with a standard deviation of ± 2 parts in 10 10 . The quartz clocks are also calibrated in terms of astronomical time and the results are compared for the period from June 1955 to June 1956. For operational purposes the frequency of the resonance was taken as 9 192 631 830 c/s which was the value obtained in terms of the unit of uniform astronomical time made available by the Royal Greenwich Observatory in June 1955. The value is being determined in terms of the second of ephemeris time, which has now been adopted by the International Committee of Weights and Measures as the unit of time, but to obtain the accuracy required the comparison must be extended over a long interval in view of the difficulties associated with the astronomical measurements.

Parametric estimates of statistical tests in digital time-interval measurements

1984 ◽  
Vol 27 (9) ◽  
pp. 774-776
Author(s):  
A. A. Os'minin ◽  
V. V. Khaustov
Keyword(s):  
Statistical Tests ◽  
Time Interval ◽  
Digital Time

Empirical earthquake probabilities from observed recurrence intervals

1994 ◽  
Vol 84 (1) ◽  
pp. 219-221 ◽  
Author(s):  
J. C. Savage
Keyword(s):  
Standard Deviation ◽  
Probability Density ◽  
Beta Distribution ◽  
Time Interval ◽  
Fault Segment ◽  
Best Estimate ◽  
Current Cycle ◽  
Recurrence Intervals

Abstract The probability p that a given fault segment will rupture within a specified time T following the preceding rupture is evaluated empirically from a sample of observed recurrence intervals for that fault segment. All that is assumed is that the probability of rupture within the specified time interval is the same for all rupture cycles on that segment. Suppose that m of the n observed recurrence intervals correspond to cycles in which rupture occurred within the interval T following the preceding earthquake. The probability density that rupture in the current cycle will also fall within the interval T following the most recent earthquake is then given by the beta distribution P(p|m, n) = {(n + 1)!/[m!(n − m!]}pm(1 − p)n−m. The best estimate of the desired probability pis 〈p〉 = (m + 1)/(n + 2), and a measure of the breadth of the distribution is the standard deviation σ = [〈p〉 (1 − 〈p〉)/(n + 3)]1/2. Because it is unlikely that the number n of observed recurrence intervals will be much greater than 10, the probability generally will not be defined more closely than ±0.2. Moreover, increasing n decreases the uncertainty only very slowly.

scholarly journals The Analysis and Suppressing of Non-Uniformity in a High-Speed Spike-Based Image Sensor

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4232 ◽  
Author(s):  
Jing Gao ◽  
Yanzhao Wang ◽  
Kaiming Nie ◽  
Zhiyuan Gao ◽  
Jiangtao Xu
Keyword(s):  
Standard Deviation ◽  
Dark Current ◽  
High Speed ◽  
Bright Light ◽  
Image Sensor ◽  
Time Interval ◽  
Temporal Noise ◽  
Spatial Noise ◽  
Calibration Algorithm ◽  
Photo Response

In this paper, the non-ideal factors, which include spatial noise and temporal noise, are analyzed and suppressed in the high-speed spike-based image sensor, which combines the high-speed scanning sequential format with the method that uses the interspike time interval to indicate the scene information. In this imager, spatial noise contains device mismatch, which results in photo response non-uniformity (PRNU) and the non-uniformity of dark current. By multiplying the measured coefficient matrix the photo response non-uniformity is suppressed, and the non-uniformity of dark current is suppressed by correcting the interspike time interval based on the time interval of dark current. The temporal noise is composed of the shot noise and thermal noise. This kind of noise can be eliminated when using the spike frequency to restore the image. The experimental results show that, based on the spike frequency method, the standard deviation of the image decreases from 18.4792 to 0.5683 in the uniform bright light by using the calibration algorithm. While in the relatively uniform dark condition, the standard deviation decreases from 1.5812 to 0.4516. Based on interspike time interval method, because of time mismatch and temporal noise, the standard deviation of the image changes from 27.4252 to 27.4977 in the uniform bright light by using the calibration algorithm. While in the uniform dark condition, the standard deviation decreases from 2.361 to 0.3678.

scholarly journals Application of Multistep Inversion Method for Online Monitoring Aerosol Particle Size Distribution and Aerosol Concentration

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhenzong He ◽  
Liang Xu ◽  
Junkui Mao ◽  
Xingsi Han ◽  
Biao Zhang
Keyword(s):  
Particle Size ◽  
Standard Deviation ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Sampling Time ◽  
Aerosol Concentration ◽  
Inversion Method ◽  
Time Interval ◽  
Aerosol Particle Size ◽  
Sampling Time Interval

Aerosol concentration in the flow is usually time varying, and aerosol particle size distribution (PSD) is considered to be unchanged, which increases the difficulty of the measurement of aerosol PSD and concentration online. To solve these problems, a kind of multistep inversion method based on the angular light-scattering (ALS) signals is proposed. First, the aerosol PSD is estimated using shuffled frog-leaping algorithms (SFLAs) from relative ALS signals. Then, with aerosol PSD as priori information, the aerosol concentration is obtained by the Kalman filter (KF) algorithm, widely used in the real-time control system of industrial facilities for its ability of fast predictions. The result reveals that the performance of the improved SFLA is better than that of the original SFLA in solving the aerosol PSD. Moreover, in studying the aerosol concentration, more accurate results can be obtained with larger standard deviation of process noise or smaller standard deviation of measurement noise, while decreasing sampling time interval can improve the accuracy of retrieval results and reduce time delay to a certain degree. So, to improve retrieval accuracy, the noise should be controlled, and appropriate sampling time interval should be selected. All the numerical simulations confirm that the methodology provides effective and reliable results in real-time estimating.

Measurement and Analysis of the Circuit Delay of CEI System

2011 ◽  
Vol 128-129 ◽  
pp. 611-615
Author(s):  
Ge Shi Tang ◽  
Li Li ◽  
Liang Zeng ◽  
Lue Chen ◽  
Lv Zhou
Keyword(s):  
Standard Deviation ◽  
Primary Data ◽  
Time Interval ◽  
Network Analyzer ◽  
Signal Source ◽  
Circuit Delay ◽  
Amplifier Output ◽  
Delay Measurement ◽  
Measurement And Analysis ◽  
Time Delay Measurement

By using a four port Vector Network Analyzer (VNA), a caesium clock, a time-interval counter and a signal source to measure the delay of CEI system segmentally. Design measuring methods respectively for three segments of the circuit. When measure the delay, it is found that, delay of antenna’s amplifier output port to the input port of down converter (DC) is stable; the fluctuation of DC’s delay is less than 2ns; the cable delay’s standard deviation is stable at 0.1ns; we get a nanosecond accuracy for whole system. The methods of time delay measurement and the design of CEI system will provide a foundation and primary data for future deep space missions.

Rack for testing digital time-interval meters

1976 ◽  
Vol 19 (9) ◽  
pp. 1371-1372
Author(s):  
V. V. Il'in
Keyword(s):  
Time Interval ◽  
Digital Time
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