High accuracy at low frequency: detailed behavioural classification from accelerometer data

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

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Analysis of the Electron Traps at the 4H-SiC/SiO2 Interface of a Gate Oxide Obtained by Wet Oxidation of a Nitrogen Pre-Implanted Layer

Materials Science Forum ◽

10.4028/www.scientific.net/msf.615-617.533 ◽

2009 ◽

Vol 615-617 ◽

pp. 533-536

Author(s):

Ioana Pintilie ◽

Francesco Moscatelli ◽

Roberta Nipoti ◽

Antonella Poggi ◽

Sandro Solmi ◽

...

Keyword(s):

Low Frequency ◽

Gate Oxide ◽

High Accuracy ◽

Interface Trap Density ◽

Interface Trap ◽

High Concentration ◽

Mos Capacitors ◽

Order Of Magnitude ◽

Good Agreement

This work is focusing on the effect of a high concentration of nitrogen (N) introduced by ion implantation at the SiO2/4H-SiC interface in MOS capacitors. The N implanted sample (Ninterface ~1x1019cm-3) is compared with a non-implanted one (Ninterface ~1x1016cm-3) by means of the electron interface trap density (Dit). The Dit is determined via High-Low frequency C-V method and Thermal Dielectric Relaxation Current (TDRC) technique. It is shown that the TDRC method, mainly used so far for determination of near interface oxide charges, can be exploited to gain information about the Dit too. The determined value of Dit in the N-implanted sample is nearly one order of magnitude lower than that in the sample without N implantation. Good agreement between the TDRC results and those obtained from High-Low frequency C-V measurements is obtained. Furthermore, the TDRC method shows a high accuracy and resolution of Dit evaluation in the region close to the majority carrier band edge and gives information about the traps located into the oxide.

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Measurements of Low Frequency Vibration in Subsea Piping Using ROV Video Analysis

Volume 4: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2020-18579 ◽

2020 ◽

Author(s):

Andries van Wijhe ◽

Lennert Buijs ◽

Leszek Stachyra ◽

Olivier Macchion

Keyword(s):

Video Analysis ◽

Video Processing ◽

Production Systems ◽

Mechanical Vibration ◽

Water Injection ◽

Low Frequency ◽

Free Vibrations ◽

Accelerometer Data ◽

Lighting Condition ◽

Low Frequency Vibration

Abstract Vibrations in Subsea Production Systems are well recognized as a concern in the subsea industry. To identify the severity of the vibrations and potential accumulated fatigue damage, subsea vibrations need to be measured with great accuracy. Currently, accurate detection and subsea measurements are often performed by utilizing accelerometers, which have to be connected to the structure by ROV or a diver. ROV video analysis provides an alternative solution. Video analyses are widely utilized across different applications. With the increased quality of a HD camera on ROV, the accessibility of such measurements is an attractive substitute to other techniques. As a part of on-shore mechanical testing on a full assembled XT in St John’s Canada, a flowloop on a water injection XT was subjected to free vibrations. The vibrations were filmed using a commercial HD camera placed on a tripod. This test was done to validate data generated using video processing in which pipe vibration of an operating subsea XT was filmed using an ROV camera. A study that aimed to quantify the video processing accuracy, limitations and provide general guidance was conducted. For the onshore test filmed with a tripod the results of video analyses were compared with the measurements obtained by means of accelerometers. For the video of an operating subsea XT filmed by an ROV, the obtained vibration frequency and direction was compared with the free mechanical vibration obtained by a FEM model. The results obtained by means of the video analysis matched well with the accelerometer data. A high accuracy was reached, as vibration displacements as low as 20% of the pixel were accurately determined in the video analysis. With respect to detection frequencies, the upper cut-off frequency was around 15 Hz determined by the video framerate. The video analysis utilizing ROV videos was found to be applicable for low frequency vibration measurements, opening the opportunity for easier and more cost effective vibration detection and monitoring. The method is also reliable for subsea application in which the camera is placed on an ROV and is thus not affected by ROV movements, subsea lighting condition and moving ocean debris.

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Parameter Estimation of Low-Frequency Signal with Negative Frequency Contribution

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.380-384.3457 ◽

2013 ◽

Vol 380-384 ◽

pp. 3457-3460 ◽

Cited By ~ 1

Author(s):

Si Wei Tan ◽

Zhi Liang Ren ◽

Jiong Sun

Keyword(s):

Parameter Estimation ◽

Phase Difference ◽

Spectrum Analysis ◽

Low Frequency ◽

High Accuracy ◽

Signal Parameter ◽

Frequency Signal ◽

Spectrum Method ◽

Analysis Theory ◽

Simulation Results

According to the problem that there is a decline in accuracy of low-frequency signal parameter estimation by using the algorithm of all-phase FFT, an improved phase difference correcting spectrum method based on all-phase FFT is proposed. The contribution of negative frequency to FFT calculation was considered while using phase difference correcting spectrum method. The all-phase FFT spectrum analysis theory was presented as well as a traditional phase difference correcting method based on it. The equations of parameter estimation such as frequency, amplitude and phase for low-frequency signals were derived with the negative frequency contribution to spectrum analysis. The simulation results show that the method proposed in this paper can be used to estimate the parameters of low-frequency signals in a high accuracy, and also achieves an improvement in anti-noise ability.

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ASIC Design of Encoding Circuit in Low Frequency Read-only RFID in Manufacturing Engineering

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.340.792 ◽

2013 ◽

Vol 340 ◽

pp. 792-796 ◽

Cited By ~ 1

Author(s):

Peng Fei Lai ◽

Wei Ping Jing

Keyword(s):

Design Method ◽

Low Frequency ◽

High Accuracy ◽

Cmos Process ◽

Phase Encoding ◽

Rfid Tag ◽

Asic Design ◽

Custom Design ◽

Manufacturing Engineering ◽

Chip Testing

For the two kinds of commonly used codes in low frequency read-only RFID tag: Manchester encoding and Differential Bi-Phase encoding, we designed the corresponding encoding circuit, as shown in Fig. 5 and Fig. 10. It was fabricated by SMIC 0.35um CMOS process through full custom design method and has been successfully applied to a read-only RFID tag based on ISO/IEC 11784/5 standard. The chip testing result shows that the designed circuit can achieve ideal encoding effect, as shown in Fig. 14 and Fig. 15, which possesses the properties of high accuracy and strong anti-disturbance.

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Attitude Measurement Low Frequency Error Identification and Compensation for Star Tracker with Gyros

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.664.298 ◽

2014 ◽

Vol 664 ◽

pp. 298-303

Author(s):

Yu Wang Lai ◽

De Feng Gu ◽

Jun Hong Liu ◽

Wen Ping Li ◽

Dong Yun Yi

Keyword(s):

Attitude Determination ◽

Low Frequency ◽

Euler Angle ◽

High Accuracy ◽

Star Tracker ◽

Attitude Motion ◽

Frequency Error ◽

Attitude Measurement ◽

Novel Approach ◽

Critical Problems

The low-frequency error (LFE) of star tracker is the most critical problems in the high accuracy attitude determination for the satellite. In this paper a novel approach is proposed to identify and compensate the attitude measurement LFE of the star trackers. The main difficulty in the attitude LFE identification is to distinguish the attitude LFE from the attitude motion. To overcome this difficulty, the gyro data, which is sensitive to the attitude motion, was used to fit the measurement attitude data to obtain the reference attitude. It is shown that, the LFE can be identified by comparing the measurement attitude and the reference attitude. The attitude LFE repeated feature is characterized well by the proposed method. By utilizing the orbital repeated feature, the LFE of the star trackers can be estimated. Finally, a LFE compensation strategy is presented base on the LFE estimation results. The validity and efficiency of the proposed approach are demonstrated by the relative Euler angle results from two test star trackers on-board the STECE satellite.

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Single molecule molecular inversion probes for targeted, high-accuracy detection of low-frequency variation

Genome Research ◽

10.1101/gr.147686.112 ◽

2013 ◽

Vol 23 (5) ◽

pp. 843-854 ◽

Cited By ~ 208

Author(s):

J. B. Hiatt ◽

C. C. Pritchard ◽

S. J. Salipante ◽

B. J. O'Roak ◽

J. Shendure

Keyword(s):

Single Molecule ◽

Low Frequency ◽

High Accuracy ◽

Frequency Variation ◽

Molecular Inversion Probes

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THE ELECTRIC RESISTANCE AND CAPACITY OF BLOOD FOR FREQUENCIES BETWEEN 800 AND 4½ MILLION CYCLES

The Journal of General Physiology ◽

10.1085/jgp.9.2.153 ◽

1925 ◽

Vol 9 (2) ◽

pp. 153-167 ◽

Cited By ~ 139

Author(s):

Hugo Fricke ◽

Sterne Morse

Keyword(s):

Experimental Data ◽

Volume Concentration ◽

Specific Resistance ◽

Low Frequency ◽

High Accuracy ◽

Electric Resistance ◽

Experimental Values

1. The variation of the experimental values (R (ω)), (C (ω)) of the resistance and capacity of blood for increasing frequencies is approximately represented by the equation: See PDF for Equation in which Ro and Co are the resistance and capacity of the blood at low frequency and See PDF for Equation is the resistance of the blood at infinite frequency. Formulæ (1) and (2) are derived by considering the blood as equivalent to the system shown in the diagram (a) of Fig. 1. 2. By the application of formula (1) to our experimental data the value of R(∞) can be extrapolated with high accuracy. R(∞) represents the resistance) which would have been obtained at low frequency, if the membranes around the corpuscles could have been removed. 3. The specific resistance of the corpuscle interior can be calculated by equation (5), using experimental values for R(∞), for the volume concentration of the blood and for the specific resistance of the serum. 4. The specific resistance of the interior of the red corpuscle of the calf is found to be 3.5 ± 10 per cent times the specific resistance of the serum.

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A Low Frequency and High-Precision Microbarograph Monitoring System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.605-607.873 ◽

2012 ◽

Vol 605-607 ◽

pp. 873-877

Author(s):

Lei Li ◽

Zhong Hai Zhou ◽

Cheng Xing Lv ◽

Bo Liu ◽

He Chao Zang ◽

...

Keyword(s):

Monitoring System ◽

High Precision ◽

Measurement Accuracy ◽

Dynamic Range ◽

Low Frequency ◽

Type A ◽

High Accuracy ◽

Signal Modulation ◽

Frequency Signal ◽

Wide Dynamic Range

A low frequency and high-precision microbarograph monitoring system is developed based on the Michelson interference of unequal-arm type, a method of signal modulation and compensation is presented, it improves the system’s anti-jamming capability and measurement accuracy. Experiments show that the monitoring system has a high accuracy and a wide dynamic range, especially for monitoring low-frequency signal.

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Pilot Experimentation of the Accuracy of Accelerometer Activity Count-Derived Breaks in Sedentary Time

Journal of Health Sciences ◽

10.17532/jhsci.2018.514 ◽

2018 ◽

Vol 8 (1) ◽

pp. 62-67

Author(s):

Paul D. Loprinzi ◽

Meghan K Edwards

Keyword(s):

Sedentary Behavior ◽

Direct Observation ◽

Sedentary Time ◽

Low Frequency ◽

Standing Position ◽

Accelerometer Data ◽

Frequency Filter ◽

Activity Count ◽

Breaks In Sedentary Time

Introduction: The purpose of this study was toconduct a pilot experimentation of the accuracy of the ActiGraph GT9X model in detecting breaks from sedentary behavior. Methods: Participants completed six transitional-based sedentary break activities while wearing an ActiGraph GT9X accelerometer. Data were processed using both the default filter and low-frequency extension filter. Direct observation was used as the criterion to observe a break in sedentary behavior. Trial 1 included the transition from sitting to standing; trial 2, sitting to walking for 30 sec; trial 3, sitting to walking for 1 min; trial 4, standing to walking for 30 sec; trial 5, standing to walking for 1 min; and trial 6, standing to sitting. Results: For both the default and low-frequency filter, the accelerometer only detected a break 10% of the time for trial 1. Accuracy was also low (<40%) for trial 6. However, accuracy was perfect (100%) for trials 2-5. Conclusion: The ActiGraph GT9X accelerometer was inaccurate in detecting a sedentary break when transitioning from a sitting to standing position but was accurate for other transitional shifts.

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