scholarly journals Gravity-Based Characterization of Three-Axis Accelerometers in Terms of Intrinsic Accelerometer Parameters

2017 ◽  
Vol 122 ◽  
Author(s):  
Jon Geist ◽  
Muhammad Yaqub Afridi ◽  
Craig D. McGray ◽  
Michael Gaitan
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Measurement Errors ◽  
Angle Measurement ◽  
Sensitivity Matrix ◽  
Cross Sensitivity ◽  
Measurement Capability ◽  
Intrinsic Parameters ◽  
The Cross ◽  
Alignment Errors

Cross-sensitivity matrices are used to translate the response of three-axis accelerometers into components of acceleration along the axes of a specified coordinate system. For inertial three-axis accelerometers, this coordinate system is often defined by the axes of a gimbal-based instrument that exposes the device to different acceleration inputs as the gimbal is rotated in the local gravitational field. Therefore, the cross-sensitivity matrix for a given three-axis accelerometer is not unique. Instead, it depends upon the orientation of the device when mounted on the gimbal. We define nine intrinsic parameters of three-axis accelerometers and describe how to measure them directly and how to calculate them from independently determined cross-sensitivity matrices. We propose that comparisons of the intrinsic parameters of three axis accelerometers that were calculated from independently determined cross-sensitivity matrices can be useful for comparisons of the cross-sensitivity-matrix measurement capability of different institutions because the intrinsic parameters will separate the accelerator-gimbal alignment differences among the participating institutions from the purely gimbal-related differences, such as gimbal-axis orthogonality errors, z-axis gravitational-field alignment errors, and angle-setting or angle-measurement errors.

scholarly journals Type B Uncertainty Analysis of Gravity-Based Determinations of Triaxial-Accelerometer Properties by Simulation of Measurement Errors

2022 ◽  
Vol 126 ◽  
Author(s):  
Jon Geist ◽  
Michael Gaitan
Keyword(s):  
Measurement Errors ◽  
Type B ◽  
Triaxial Accelerometer ◽  
Calibration System ◽  
Intrinsic Properties ◽  
Step Size ◽  
Sensitivity Matrix ◽  
The Individual ◽  
Rotation Stage ◽  
Alignment Errors

We simulated the effects of gimbal-alignment errors and rotational step-size errors on measurements of the sensitivity matrix and intrinsic properties of a triaxial accelerometer. We restricted the study to measurements carried out on a two-axis calibration system using a previously described measurement and analysis protocol. As well as imperfections in the calibration system, we simulated imperfect orthogonality of the accelerometer axes and non-identical sensitivity of the individual accelerometers in an otherwise perfect triaxial accelerometer, but we left characterization of other accelerometer imperfections such as non-linearity for future study. Within this framework, sensitivity-matrix errors are caused by imperfections in the construction and installation of the accelerometer calibration system, but not by the accelerometer imperfections included in the simulations. We use the results of this study to assign type B uncertainties to the components of the sensitivity matrix and related intrinsic properties due to imperfections in the measurement system. For calibrations using a reasonably well manufactured and installed multi-axis rotation stage such as that studied in this paper, we estimated upper bounds to the standard uncertainties of the order of 1 ×10−5 , 2 ×10−5 , 2 ×10−4 , and 5 ×10−5 for the intrinsic sensitivities, diagonal elements of the sensitivity matrix, off-diagonal elements of the sensitivity matrix, and zero-acceleration offsets, relative to a sensitivity-matrix element of 1, respectively, and 5 ×10−3 degrees for the intrinsic angles

The spin-zero Duffin-Kemmer-Petiau equation in a cosmic-string space-time with the Cornell interaction

2016 ◽  
Vol 31 (36) ◽  
pp. 1650191 ◽  
Author(s):  
M. de Montigny ◽  
M. Hosseinpour ◽  
H. Hassanabadi
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Cosmic String ◽  
Topological Defects ◽  
Space Time ◽  
Dkp Equation

In this paper, we study the covariant Duffin-Kemmer-Petiau (DKP) equation in the cosmic-string space-time and consider the interaction of a DKP field with the gravitational field produced by topological defects in order to examine the influence of topology on this system. We solve the spin-zero DKP oscillator in the presence of the Cornell interaction with a rotating coordinate system in an exact analytical manner for nodeless and one-node states by proposing a proper ansatz solution.

Cross-Sensitivity Characteristics of Instrumented Wheelset Associated With Longitudinal Force and Lateral Contact Position

2021 ◽  
Author(s):  
Takatoshi Hondo ◽  
Takayuki Tanaka ◽  
Shoya Kuniyuki ◽  
Mitsugi Suzuki
Keyword(s):  
Measurement Accuracy ◽  
Contact Point ◽  
Fem Analysis ◽  
Longitudinal Force ◽  
Lateral Position ◽  
Contact Forces ◽  
Load Test ◽  
Static Load Test ◽  
Cross Sensitivity ◽  
The Cross

Abstract It is crucial to grasp wheel-rail contact forces in the evaluation of running safety and curving performance of railway vehicles. To measure the wheel-rail contact forces, instrumented wheelset, which has the strain gauges on the wheel surface, is widely used. The purpose of this research is to increase the measurement accuracy of the wheel-rail contact forces by understanding the detailed characteristics of the instrumented wheelset. Although the various researches on the instrumented wheelset have been carried out to increase the measurement accuracy of wheel-rail contact forces, there are few works considering the longitudinal force and the lateral shift of the wheel-rail contact point. However, sometimes the longitudinal force has a non-negligible influence on the measurement accuracy on the instrumented wheelset. In this paper, the authors clarify the cross-sensitivity characteristics of the instrumented wheelset when the longitudinal force is applied to the various lateral position on the wheel tread through the FEM analysis and the static load test. The authors also propose a method to approximate the cross-sensitivity as an analytical function of the lateral and circumferential contact positions.

Influencing factors of rotary table geometric error measurement using four-station laser tracers

2021 ◽  
Author(s):  
Jun Zha
Keyword(s):  
Coordinate System ◽  
Influencing Factors ◽  
Measurement Errors ◽  
Geometric Error ◽  
Measurement Process ◽  
Length Measurement ◽  
Numerical Control ◽  
Error Measurement ◽  
Rotary Table ◽  
Geometric Error Measurement

Abstract The laser tracer multi-station measurement method has outstanding performance in computerized numerical control (CNC) rotary table geometric error measurement and separation. However, external factors, such as layout, selected distance between the target mirror and measurement coordinate system, uncertainty of the length measurement, selection of measuring radii for the rotary table, and installation deviation from the target mirror center to the rotary table surface, have negative effects on the results. In this research, the position dilution of precision in the global positioning system measurement process is introduced to evaluate the influence of the laser tracers’ positions on measurement errors. The optimal measurement layout of the laser tracer is used to select the distance between the target mirror and XY plane of the laser tracer measurement coordinate system for the simulation. Then, the influence of the length measurement uncertainty on the laser tracer self-calibration and point measurement results used for calibration is examined based on the Monte Carlo simulation method. Different measurement radii in the rotary table are selected, and four-station laser tracers are used to perform the virtual measurement and evaluate the maximum uncertainty in the X, Y, and Z directions to further determine the best measurement radii of the CNC rotary table. Finally, the effects of the deviation of the target mirror installation center on the geometric error items of the CNC rotary table are quantitatively examined through a simulation. The analysis of the influencing factors in the geometric error measurement and separation process of the CNC rotary table can help further understand how the final results are formed, so as to control the influencing factors during the measurement process and finally optimize them in practice.

Computational Investigation on the Dispersive Transport of Angiographic Contrast Injected Antegradely Into Flow in a Tube

2007 ◽  
Author(s):  
Qing Hao ◽  
Baruch B. Lieber
Keyword(s):  
Coordinate System ◽  
Cross Section ◽  
Single Molecule ◽  
Molecular Diffusion ◽  
Local Concentration ◽  
Dispersive Transport ◽  
Cross Sectional ◽  
Advection Dispersion ◽  
The Cross ◽  
The Difference

When a solute such as angiographic contrast is introduced into a solvent such as blood analog fluid flowing in a straight circular tube, it spreads under the combined action of molecule diffusion and the variation of velocity over the cross-section [8]. If two molecules are being carried in the flow, for example, one in the center and one near the wall, the rate of separation caused by the difference in bulk velocity will greatly exceed that caused by molecule motion. Given enough time, any single molecule would wander randomly throughout the cross section of the pipe because of molecular diffusion, and would sample at random all the advective velocities [4]. Therefore, Taylor [8] adopted the Lagrangian approach to the problem, casting the equations in a coordinate system that moves with the average velocity of the flow and replacing the molecular diffusion coefficient with a dispersion coefficient, and the local concentration with the cross sectional mean concentration. Recasting Taylor’s equation in an inertial coordinate system one obtained the so called advection-dispersion equation.

scholarly journals Approximate Inertial Coordinate System Selections for Rotation Problems - The Gravitational Field of the Celestial Body Higher than the Object Being Rotated

2015 ◽  
Vol 8 (1) ◽  
pp. 102
Author(s):  
Zifeng Li
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Celestial Body ◽  
Angular Speed ◽  
Calculation Error ◽  
Cartesian Coordinate System ◽  
Inertial Coordinate System ◽  
The Earth ◽  
The Galaxy ◽  
Cartesian Coordinate

<p class="1Body">Selection of the coordinate system is essential for rotation problems. Otherwise, mistakes may occur due to inaccurate measurement of angular speed. Approximate inertial coordinate system selections for rotation problems should be the gravitational field of the celestial body higher than the object being rotated: (1) the Earth fixed Cartesian coordinate system for normal rotation problem; (2) heliocentric - geocentric Cartesian coordinate system for satellites orbiting the Earth; (3) the Galaxy Heart - heliocentric Cartesian coordinates for Earth's rotation around the Sun. In astrophysics, mass calculation error and angular velocity measurement error lead to a black hole conjecture.</p>

scholarly journals Tilted Fiber Bragg Grating Sensor Using Chemical Plating of a Palladium Membrane for the Detection of Hydrogen Leakage

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4478 ◽  
Author(s):  
Jiachen Yu ◽  
Zhenlin Wu ◽  
Xin Yang ◽  
Xiuyou Han ◽  
Mingshan Zhao
Keyword(s):  
Fiber Bragg Grating ◽  
Low Cost ◽  
Hydrogen Sensor ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Cross Sensitivity ◽  
Chemical Plating ◽  
Palladium Membrane ◽  
Surrounding Refractive Index ◽  
The Cross

A tilted fiber Bragg grating (TFBG) hydrogen sensor coated with a palladium (Pd) membrane by the electroless plating method is proposed in this paper. A uniform layer of Pd metal is fabricated in aqueous solutions by the chemical coating method, which is used as the sensitive element to detect the change of the surrounding refractive index (SRI) caused by hydrogen absorption. The change in SRI causes an unsynchronized change of the cladding modes and the Bragg peak in the TFBG transmission spectrum, thereby eliminating the cross-sensitivity due to membrane expansion and is able to simultaneously monitor the presence of cracks in the pipe, as well as the hydrogen leakage. By subtracting the wavelength shift caused by fiber expansion, the change of SRI, i.e., the information from the H2 level, can be separately obtained. The drifted wavelength is measured for the H2 concentration below the hydrogen explosion limit between 1% and 4%. The chemical-based coating has the advantages of a low cost, a simple operation, and being suitable for coating on long fiber structures. The proposed sensor is able to detect the H2 signal in 5 min at a 1% H2 concentration. The proposed sensor is proved to be able to monitor the hydrogen level without the cross-sensitivity of temperature variation and expansion strains, so could be a good candidate for security applications in industry.

Reduced conformal geometrodynamics

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040023 ◽  
Author(s):  
Andrej B. Arbuzov ◽  
Alexander E. Pavlov
Keyword(s):  
Gravitational Field ◽  
Dynamical Systems ◽  
Coordinate System ◽  
Tangent Space ◽  
Equations Of Motion ◽  
Mean Value ◽  
Hamiltonian Reduction ◽  
Square Root ◽  
The Mean ◽  
Static Background

The global time in geometrodynamics is defined in a covariant under diffeomorphisms form. An arbitrary static background metric is taken in the tangent space. The global intrinsic time is identified with the mean value of the logarithm of the square root of the ratio of the metric determinants. The procedures of the Hamiltonian reduction and deparametrization of dynamical systems are implemented. The reduced Hamiltonian equations of motion of gravitational field in semi-geodesic coordinate system are written.

Photoproduction of gravitons in a static magnetic dipole field due to currents

1978 ◽  
Vol 56 (6) ◽  
pp. 801-805 ◽  
Author(s):  
G. Papini ◽  
S. R. Valluri
Keyword(s):  
Gravitational Field ◽  
Magnetic Dipole ◽  
Cross Section ◽  
Dipole Field ◽  
Radiative Corrections ◽  
Gauge Invariant ◽  
Magnetic Dipole Field ◽  
The Cross

The cross section for the photoproduction of gravitons in magnetic dipole fields which are due to steady currents is calculated. The approach and the results are compared with the previously studied case in which no currents exist and the potential is represented by a scalar. The calculations in both cases are completely covariant and electromagnetically gauge invariant. The radiative corrections to order [Formula: see text] and [Formula: see text] in the nonrelativistic and relativistic limits are also calculated for dipole and Coulomb fields, respectively. Their evaluation is particularly simple in the transverse traceless gauge for the gravitational field.

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