scholarly journals The ATS-F/NIMBUS-E Tracking Experiment

1972 ◽  
Vol 48 ◽  
pp. 112-120 ◽  
Author(s):  
F. O. von Bun
Keyword(s):  
Integration Time ◽  
Time Interval ◽  
Tracking Systems ◽  
Tracking Errors ◽  
Original Intent ◽  
Laser Tracking ◽  
Ground Station ◽  
Error Analyses ◽  
Range Rate

In this paper the objective of the ATS-F/NIMBUS-E Tracking Experiment, the first of such kind, is presented. Specifically, this experiment has a two-fold purpose: First, to gain experience in the practical use of satellite-to-satellite range and range rate data for very accurate orbit determination (this was its original intent); and second, to evaluate the real usefulness of such a technique for geodetic studies despite the fact that the 1000 km NIMBUS orbit is not ideally suited for such a purpose.The accuracies of the tracking systems of the satellite-to-satellite and satellite-to-ground link (ATS-F to the Rosman, N.C. ground station) will be ~ 0.035 cm/s in range rate and ~ 1 m in range – utilizing a 10 s integration time. With these values one obtains, based upon performed error analyses, orbit height errors in the order of 0.1 to 0.3 m for the near earth orbiting NIMBUS spacecraft. This experiment will therefore hopefully prove to be a significant first step for future Earth applications spacecraft carrying altimeters systems for measuring ocean height variations.In addition, laser corner reflectors placed on board the ATS-F will make a total independent position determination of this spacecraft to approximately 15 m to 30 m possible, assuming that the location errors of four laser tracking stations used to determine the orbit are about 3 m or 5 m in each component respectively, with laser ranging system noise errors of 1.2 m and bias errors of 0.15 m. A small position error of the ATS-F, the ‘orbiting tracking station’ is essential in order to make full usage of the small satellite-to-satellite tracking errors mentioned.For purpose of geodetic studies, one of the final goals, range rate variations of 0.1 cm/s or less corresponding to surface gravity anomaly of 20 mgal or less (over a half-width of 100 km on the Earth surface), will have to be measured during a time interval of approximately, say, 30–60 s. These values are within the range of the planned tracking systems accuracies for ATS-F and NIMBUS-E.

Error analyses of a Multi-Input-Multi-Output cantilever beam test

2021 ◽  
pp. 107754632110337
Author(s):  
Arup Maji ◽  
Fernando Moreu ◽  
James Woodall ◽  
Maimuna Hossain
Keyword(s):  
Transfer Function ◽  
Frequency Domain ◽  
Cantilever Beam ◽  
Transfer Functions ◽  
Linear Superposition ◽  
Transfer Function Matrix ◽  
Error Analyses ◽  
Pseudo Inverse ◽  
Function Matrix

Multi-Input-Multi-Output vibration testing typically requires the determination of inputs to achieve desired response at multiple locations. First, the responses due to each input are quantified in terms of complex transfer functions in the frequency domain. In this study, two Inputs and five Responses were used leading to a 5 × 2 transfer function matrix. Inputs corresponding to the desired Responses are then computed by inversion of the rectangular matrix using Pseudo-Inverse techniques that involve least-squared solutions. It is important to understand and quantify the various sources of errors in this process toward improved implementation of Multi-Input-Multi-Output testing. In this article, tests on a cantilever beam with two actuators (input controlled smart shakers) were used as Inputs while acceleration Responses were measured at five locations including the two input locations. Variation among tests was quantified including its impact on transfer functions across the relevant frequency domain. Accuracy of linear superposition of the influence of two actuators was quantified to investigate the influence of relative phase information. Finally, the accuracy of the Multi-Input-Multi-Output inversion process was investigated while varying the number of Responses from 2 (square transfer function matrix) to 5 (full-rectangular transfer function matrix). Results were examined in the context of the resonances and anti-resonances of the system as well as the ability of the actuators to provide actuation energy across the domain. Improved understanding of the sources of uncertainty from this study can be used for more complex Multi-Input-Multi-Output experiments.

High-Performance Liquid Chromatographic Determination of Memantine in Human Urine Following Solid-Phase Extraction and Precolumn Derivatization

2013 ◽  
Vol 96 (6) ◽  
pp. 1302-1307 ◽  
Author(s):  
Karim Michail ◽  
Hoda Daabees ◽  
Youssef Beltagy ◽  
Magdy Abd Elkhalek ◽  
Mona Khamis
Keyword(s):  
Human Urine ◽  
High Performance ◽  
Solid Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Therapeutic Drug ◽  
Time Interval ◽  
Precolumn Derivatization ◽  
Uv Detector

Abstract A validated HPLC-UV method is presented for the quantification of urinary memantine hydrochloride, a novel medication approved to treat moderate and advanced cases of Alzheimer's disease. The drug and amantadine hydrochloride, the internal standard, were extracted from human urine using SPE. The extract was then buffered and derivatized at room temperature using o-phthalaldehyde in the presence of N-acetyl-L-cyteine. Chromatographic separation of the formed derivatives was achieved on a C18 column using methanol–water mobile phase adjusted to pH 7 and pumped isocratically at 1 mL/min. The UV detector was set at 340 nm. The chromatographic run time did not exceed 10 min. The LOD and LOQ were 8 and 20 ng/mL, respectively. The RSDs for intraday and interday precisions did not exceed 5.5%. The method was used to monitor memantine hydrochloride in human urine in order to determine an appropriate sampling interval for future noninvasive therapeutic drug monitoring. The assay could also be applied to the determination of amantadine. The described assay showed that a postdosing time interval of 25–75 h seems adequate for sampling and monitoring memantine in urine.

Lack of Agreement of Tympanic Membrane Temperature Assessments With Conventional Methods in a Private Practice Setting

PEDIATRICS ◽  
1992 ◽  
Vol 89 (3) ◽  
pp. 384-386
Author(s):  
Gary L. Freed ◽  
J. Kennard Fraley
Keyword(s):  
Regression Analysis ◽  
Tympanic Membrane ◽  
Otitis Media ◽  
Time Interval ◽  
Limits Of Agreement ◽  
Temperature Determination ◽  
Conventional Methods ◽  
Clinical Instrument ◽  
Lower Limits

An infrared tympanic membrane thermometer (FIRST temp) said to approximate core temperature accurately is being marketed as a noninvasive, quick, and easy-to-use clinical instrument. The determination of tympanic membrane temperatures by this device was compared with the determination of oral, rectal, or axillary temperatures by a conventional glass thermometer. Subjects were patients of a pediatric group practice in Houston, Texas. FIRST temp and conventional temperature determinations on individual patients were completed within 5 minutes of each other. The presence or absence of otitis media was noted by the examining physician. Agreement between the two methods of temperature determination was assessed by calculating limits of agreement within which 95% (±2 standard deviations) of individual differences would fall. The location of conventional thermometer (oral, rectal, axillary), time interval between the two separate measures, and the presence or absence of otitis media were entered into a multiple regression analysis to determine whether these factors influenced the observed differences between the two methods. A total of 144 patients were enrolled in the study; oral comparisons were obtained in 92 (57%) patients, rectal in 35 (24%), and axillary in 29 (19%). The upper and lower limits of agreement between temperature methods were 1.12°C and 0.89°C and the mean difference was –0.12°C. Regression analysis revealed that only the site of conventional thermometer location (oral, rectal, axillary) was a significant predictor of FIRST temp/conventional differences. Each site had a range of agreement greater than 1.65°C; axillary temperatures had the greatest range (–0.94°C to +1.30°C). Although ease and time reduction with use are attractive properties of the FIRST temp device, these data show that it is unreliable compared with conventional methods of temperature determination.

Two-component gas sensing with MIR dual comb spectroscopy

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Leonard Nitzsche ◽  
Jens Goldschmidt ◽  
Armin Lambrecht ◽  
Jürgen Wöllenstein
Keyword(s):  
Carbon Monoxide ◽  
Nitrous Oxide ◽  
Gas Sensing ◽  
Integration Time ◽  
Relative Precision ◽  
Acquisition Rate ◽  
Mid Infrared ◽  
Two Component ◽  
Absorption Features

Abstract A dual comb spectrometer is used as gas sensor for the parallel detection of nitrous oxide (N2O) and carbon monoxide (CO). These gases have overlapping absorption features in the mid-infrared (MIR) at a wavelength of 4.6 µm. With a spectra acquisition rate of 10 Hz, concentrations of 50 ppm N2O and 30 ppm CO are monitored with a relative precision of 6 × 10 − 3 6\times {10^{-3}} and 3 × 10 − 3 3\times {10^{-3}} respectively. The limit of detections are 91 ppb for N2O and 50 ppb for CO for an integration time of 25 s. The system exhibits a linear sensitivity from 2 ppm to 100 ppm with coefficients of determination of 0.99998 for N2O and 0.99996 for CO.

Identification of Forces in Vibrating Plates by Pointwise and Line Observations: Uniqueness and Stability

1995 ◽  
Author(s):  
Masahiro Yamamoto
Keyword(s):  
Finite Time ◽  
Large Time ◽  
Single Point ◽  
Time Interval ◽  
Finite Time Interval ◽  
Line Parallel ◽  
Vibrating Plates ◽  
External Forces ◽  
Spatially Varying

Abstract We consider determination of spatially varying external forces in a rectangle vibrating plate from displacement observed along a line parallel to a side of the plate over a finite time interval. For a suitable choice of the line and a sufficient large time interval, we prove the uniqueness of external forces and estimate them by appropriate norm of displacement. Moreover we discuss determination of external forces from displacement observed at a single point over a time interval.

scholarly journals New Results on the Motions of Asteroids in Resonances

1992 ◽  
Vol 152 ◽  
pp. 145-152 ◽  
Author(s):  
R. Dvorak
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Close Approach ◽  
Integration Time ◽  
Time Interval ◽  
Time Intervals ◽  
3 Dimensional ◽  
Special Cases ◽  
Good Agreement

In this article we present a numerical study of the motion of asteroids in the 2:1 and 3:1 resonance with Jupiter. We integrated the equations of motion of the elliptic restricted 3-body problem for a great number of initial conditions within this 2 resonances for a time interval of 104 periods and for special cases even longer (which corresponds in the the Sun-Jupiter system to time intervals up to 106 years). We present our results in the form of 3-dimensional diagrams (initial a versus initial e, and in the z-axes the highest value of the eccentricity during the whole integration time). In the 3:1 resonance an eccentricity higher than 0.3 can lead to a close approach to Mars and hence to an escape from the resonance. Asteroids in the 2:1 resonance with Jupiter with eccentricities higher than 0.5 suffer from possible close approaches to Jupiter itself and then again this leads in general to an escape from the resonance. In both resonances we found possible regions of escape (chaotic regions), but only for initial eccentricities e > 0.15. The comparison with recent results show quite a good agreement for the structure of the 3:1 resonance. For motions in the 2:1 resonance our numeric results are in contradiction to others: high eccentric orbits are also found which may lead to escapes and consequently to a depletion of this resonant regions.

Determination of Polar Motion and Earth Rotation from Laser Tracking of Satellites

1979 ◽  
Vol 82 ◽  
pp. 231-238 ◽  
Author(s):  
David E. Smith ◽  
Ronald Kolenkiewicz ◽  
Peter J. Dunn ◽  
Mark Torrence
Keyword(s):  
Gravity Field ◽  
Radiation Pressure ◽  
Orbit Determination ◽  
Earth Rotation ◽  
Polar Motion ◽  
Ocean Tides ◽  
Earth’S Gravity Field ◽  
Laser Tracking ◽  
Order Of Magnitude

Laser tracking of the Lageos spacecraft has been used to derive the position of the Earth's pole of rotation at 5-day intervals during October, November and December 1976. The estimated precision of the results is 0.01 to 0.02 arcseconds in both x and y components, although the formal uncertainty is an order of magnitude better, and there is general agreement with the Bureau International de l'Heure smoothed pole path to about 0.02 arcseconds. Present orbit determination capability of Lageos is limited to about 25 cm rms fit to data over periods of 5 days and about 50 cm over 50 days. The present major sources of error in the perturbations of Lageos are Earth and ocean tides followed by the Earth's gravity field, and solar and Earth reflected radiation pressure. Ultimate accuracy for polar motion and Earth rotation from Lageos after improved modeling of the perturbing forces appears to be of order ± 5 cm for polar motion over a period of about 1 day and about ± 0.2 to ± 0.3 milliseconds in U.T. for periods up to 2 or 3 months.

scholarly journals Determination of Resonance terms using Optical Observations of Two Meteosat Satellites

1997 ◽  
Vol 165 ◽  
pp. 355-360
Author(s):  
U. Hugentobler ◽  
T. Schildknecht ◽  
G. Beutler
Keyword(s):  
Radiation Pressure ◽  
Ccd Camera ◽  
Least Square ◽  
Optical Observations ◽  
Laser Ranging ◽  
Time Interval ◽  
Orbital Parameters ◽  
Adjustment Procedure ◽  
Relative Errors

AbstractDuring an observation campaign in winter 94/95 astrometric positions from Meteosat 4 and 5 were acquired at the Zimmerwald observatory using a CCD camera mounted in the prime focus of the 0.5 m Satellite Laser Ranging telescope. The measurements cover a time interval of four months, their precision is of the order of .The modeling of radiation pressure for the small, cylindrically shaped satellites is relatively easy and they are therefore excellent objects to probe the geopotential. The orbital parameters and the radiation pressure coefficients for the two satellites as well as the resonant coefficients C22, S22 of the geopotential were determined by a single least square adjustment procedure including all the Zimmerwald observations. The relative errors estimated for the terms C22 and S22 are of the order of 1 ÷ 3 · 10−4.

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