The Use of Low Frequency Radio Aids in Supersonic Aircraft

1964 ◽  
Vol 17 (1) ◽  
pp. 57-65 ◽  
Author(s):  
V. H. King ◽  
W. E. J. Groves
Keyword(s):  
Navigation System ◽  
Low Frequency ◽  
Supersonic Flight ◽  
Transport Aircraft ◽  
Supersonic Transport ◽  
Supersonic Aircraft ◽  
Flight Regimes ◽  
Relationship Of ◽  
The Relationship

This paper first considers the characteristics of the supersonic transport aircraft (S.S.T.) as established by various international authorities and, on the basis of these characteristics, endeavours to deduce the operational requirements for a navigation system. An indication is then given of the extent to which low frequency radio aids (such as Decca and Harco) can meet these requirements in the subsonic, transition and supersonic flight regimes, whilst discussing the relationship of these ground-based systems to self-contained aids. The paper was presented, in a fuller version, at the meeting of the Deutsche Gesselschaft fiir Ortung und Navigation held in Berlin, 22–7 April 1963.

The relationship of low-frequency deep variability near the HEBBLE site to Gulf Stream fluctuations

1991 ◽  
Vol 99 (3-4) ◽  
pp. 303-317 ◽  
Author(s):  
Elizabeth B Welsh ◽  
Nelson G Hogg ◽  
Ross M Hendry
Keyword(s):  
Gulf Stream ◽  
Low Frequency ◽  
Relationship Of ◽  
The Relationship

Reliance on Visual Imagery and its Relation to Mental Rotation

1997 ◽  
Vol 85 (2) ◽  
pp. 431-434 ◽  
Author(s):  
Doris C. Weatherly ◽  
Steven E. Ball ◽  
James R. Stacks
Keyword(s):  
Mental Rotation ◽  
Response Latency ◽  
High Frequency ◽  
Visual Imagery ◽  
Learning Effect ◽  
Low Frequency ◽  
Computer Screen ◽  
The Right ◽  
Relationship Of ◽  
The Relationship

The relationship of habitual use of visual imagery and mental rotation was investigated. Reliance on Visual Imagery scores were used to define subjects as high frequency or low frequency visualizers. During the mental rotation task, subjects indicated if a pair of 2-dimensional stimulus figures displayed on a computer screen were identical or mirror-images. Figures on the right were rotated in relation to those on the left by 0, 60, 120, or 180°. Data supported the prediction that subjects who report high use of imagery would perform the task with greater accuracy ( z=1.97, p<.05) than subjects who reported low use. The imagery groups did not differ in response latency ( z = .91, p<.36). A comparison of performance on Trials 1 to 24 with performance on Trials 115-138 indicated a learning effect in both accuracy ( z = 7.58, p<.01) and latency ( z = 9.72, p<.01) for all subjects.

Harmonic and transient fields on the surface of a two‐layer medium

Geophysics ◽  
1979 ◽  
Vol 44 (7) ◽  
pp. 1208-1217 ◽  
Author(s):  
Alexander A. Kaufman
Keyword(s):  
Low Frequency ◽  
Vertical Axis ◽  
Fractional Powers ◽  
Circular Loop ◽  
Ore Body ◽  
Layer Medium ◽  
Relationship Of ◽  
The Relationship ◽  
Finite Extent ◽  
Depth Of Investigation

The article deals with the behavior of the quasi‐static electromagnetic (EM) fields created by currents in a two‐layer medium when the source is a vertical axis circular loop. This analysis is of use for determining the depth of investigation of induction methods in mining prospecting. The relationship of the active and reactive components of the field with the geoelectrical parameters is different, depending on the range of frequencies. Unlike the case of a confined body, the low‐frequency part of the spectrum is presented as a series made up of integral and fractional powers of frequency ω and also logarithmic terms of ω. The late stage of a transient process is described with a sum of terms, proportional to the inverse power of time t. These representations are useful for determining the host rock effect against which the signal from an ore body of finite extent must be detected.

scholarly journals Low-frequency ionospheric sounding with Narrow Bipolar Event lightning radio emissions: energy-reflectivity spectrum

2008 ◽  
Vol 26 (7) ◽  
pp. 1793-1803 ◽  
Author(s):  
A. R. Jacobson ◽  
R. Holzworth ◽  
X.-M. Shao
Keyword(s):  
Lightning Discharge ◽  
Low Frequency ◽  
Lower Ionosphere ◽  
Angle Of Incidence ◽  
Radio Emissions ◽  
Statistical Variation ◽  
Reflection Height ◽  
D Region ◽  
Relationship Of ◽  
The Relationship

Abstract. We analyze data on radio-reflection from the D-region of the lower ionosphere, retrieving the energy-reflection coefficient in the frequency range ~5–95 kHz. The data are the same as developed for a recent study of ionospheric-reflection height, and are based on recordings of powerful (multi-Gigawatt) radio emissions from a type of narrow (~10 μs) lightning discharge known as "Narrow Bipolar Events". The sequential appearance of first the groundwave signal, and then the ionospheric single-hop reflection signal, permits us to construct the energy-reflection ratio. We infer the energy reflection's statistical variation with solar zenith angle, angle-of-incidence, frequency, and propagation azimuth. There is also a marginally-significant response of the energy reflectivity to solar X-ray flux density. Finally, we review the relationship of our results to previous published reports.

Structural parameters optimization of a comb-like structure using locally resonant phononic crystals

2019 ◽  
Vol 33 (26) ◽  
pp. 1950312 ◽  
Author(s):  
Hongfeng Zhai ◽  
Hang Xiang ◽  
Xingfu Ma ◽  
Jiawei Xiang
Keyword(s):  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Parameters Optimization ◽  
Functional Relationships ◽  
Elastic Beams ◽  
Surface Method ◽  
Two Factors ◽  
Relationship Of ◽  
The Relationship

In this paper, a comb-like locally resonant phononic crystal (LRPC) with optimal structural parameters, which has good low frequency and broadband band gaps (BGs) between 20–250 Hz, is investigated numerically. With the intention of obtaining the optimal structural parameters, based on the structures with different number of the short elastic beams, 2-factor (the two key structural parameters, i.e. the width of the scatterer and the thickness of elastic beams) and 7-level numerical experiments are designed to obtain simulations data using finite element method (FEM). The functional relationships are further constructed using the response surface method (RSM) analysis, i.e. the relationship of the starting frequency of the first BG and the two factors, the terminating frequency of the second BG and the two factors, and the relationship of the total bandwidth of the first two BG and the two factors. After calculation using interior point method, the BGs of LRPC with optimal structural parameters are determined with lower and wider BGs below 250 Hz.

The Relationship of Tidal and Low-Frequency Currents on the North Slope of Georges Bank

1980 ◽  
Vol 10 (8) ◽  
pp. 1200-1212 ◽  
Author(s):  
Bruce A. Magnell ◽  
Stanley L. Spiegel ◽  
Richard I. Scarlet ◽  
J. Bruce Andrews
Keyword(s):  
Low Frequency ◽  
North Slope ◽  
Georges Bank ◽  
The North ◽  
Relationship Of ◽  
The Relationship

Memorability, Word Frequency and Negative Recognition

1977 ◽  
Vol 29 (3) ◽  
pp. 461-473 ◽  
Author(s):  
J. Brown ◽  
V. J. Lewis ◽  
A. F. Monk
Keyword(s):  
Word Frequency ◽  
Recognition Test ◽  
High Frequency ◽  
Low Frequency ◽  
Category Rating ◽  
Input List ◽  
Specific Prediction ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship

Brown (1976) has provided an analysis of the effect of the memorability of an item on the confidence with which it is accepted or rejected in a test of recognition or recall. When the subject has no clear recollection of the inclusion of an item in an input list, he is assumed to evaluate its memorability in the context of the experiment before he decides whether to accept or reject it. If the judged memorability is high, the absence of a clear recollection is stronger evidence against the item than if it is low. A specific prediction is that memorable distractors in a recognition test will be more confidently rejected than non-memorable ones. This prediction was tested and confirmed in three experiments in which recognition was tested by 4-category rating. Except in Experiment I, items memorable to individual subjects were identified by administering a questionnaire. For example, in Experiment III forenames of immediate family were assumed to have high memorability. This experiment also included word frequency as a variable. Low-frequency distractors were rejected significantly more firmly than high-frequency distractors: extraction of memorable names enhanced this effect. The relationship of memorability to word frequency is discussed.

scholarly journals An examination of single day vs. multi-day heart rate variability and its relationship to heart rate recovery following maximal aerobic exercise in females

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Emily Bechke ◽  
Brian Kliszczewicz ◽  
Cherilyn McLester ◽  
Mark Tillman ◽  
Michael Esco ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Maximal Exercise ◽  
Heart Rate Recovery ◽  
Low Frequency ◽  
Graded Exercise Test ◽  
Graded Exercise ◽  
Relationship Of ◽  
The Relationship ◽  
Active Cool

Abstract The purpose of this study was to examine the relationship of a single day measure of heart rate variability (HRV), and the averaged baseline measures of HRV to heart rate recovery (HRR) following maximal exercise. Thirty females (22.9 ± 3.2 years, 64.8 ± 8.4 kg) completed four visits (V1–V4), where a 10-min HRV was recorded. Upon completing the V4 recording, a treadmill graded exercise test (GXT) was performed, followed by a 5-min active cool down. HRV was assessed through time domain measures [natural log of root mean square of successive R–R differences (lnRMSSD) and standard deviation of normal to normal intervals (lnSDNN)] and natural log frequency domain measures [low frequency (lnLF) and high frequency (lnHF)]. Variables collected over V1–V4 were measured as; day of (DO) GXT, 3 day (AV3), and 4 day average (AV4). HRR was calculated as the maximal HR achieved minus the HR at: 30-s (HRR30), 1-min (HRR1), 2-min (HRR2), 3-min (HRR3), 4-min (HRR4) or 5-min (HRR5) of recovery. Pearson’s Product correlations revealed significant correlations (P = < 0.05) between all HRVDO measures to each HRR measure and are presented in ranges: lnSDNN (r = 0.442–0.522), lnRMSSD (r = 0.458–0.514), lnLF (r = 0.368–0.469), lnHF (r = 0.422–0.493). For HRVAV3, lnRMSSDAV3 and HRR1 were positively correlated (r = 0.390, P = 0.033). Last, HRVAV4 showed positive relationships (P = < 0.05) between lnRMSSDAV4 and HRR30 (r = 0.365, P = 0.048); and for HRR1 and lnSDNNAV4 (r = 0.400, P = 0.029), lnRMSSDAV4 (r = 0.442, P = 0.014), and lnHFAV4 (r = 0.368, P = 0.045); and lnRMSSDAV4 and HRR3 (r = 0.381, P = 0.038). Within the current study HRVDO displayed the strongest correlations to HRR therefore, averaged resting HRV measures do not strengthen the prediction of cardiovascular recovery following a GXT in this population.

WHISTLERS AND MAGNETIC ACTIVITY

1962 ◽  
Vol 40 (6) ◽  
pp. 775-781 ◽  
Author(s):  
R. E. Barrington ◽  
W. E. Thompson
Keyword(s):  
Seasonal Change ◽  
Low Frequency ◽  
Magnetic Activity ◽  
Diurnal Variations ◽  
Very Low Frequency ◽  
Outer Ionosphere ◽  
Recorded Data ◽  
Almost All ◽  
Relationship Of ◽  
The Relationship

The relationship between whistlers and magnetic activity was studied using planetary K indices and a whistler occurrence index. This index, Wk, is the percentage of observing periods with a given Kp value during which at least one whistler was recorded. Data from eight whistler stations which were operated during the I.G.Y. were used. In almost all cases, the value of Wk was found to increase with Kp up to Kp values of 1–3, and then decrease as Kp is further increased. The decrease of Wk with increasing Kp is shown to be due in part to masking of whistlers by very low-frequency emissions, but this does not account for the whole effect. No diurnal variations of the relationship of Wk to Kp was detected, but a small seasonal change was observed. The formation and destruction of ducts or columns of enhanced ionization in the outer ionosphere are suggested as possible mechanisms for explaining some of the observed effects.

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