scholarly journals A Review of the Research and Development of High-Frequency Measurement Technologies Used for Nonlinear Dynamics of Drillstring

2021 ◽  
Vol 2021 ◽  
pp. 1-27
Author(s):  
Lixin Li ◽  
Jin Wang ◽  
Yingmei Yu ◽  
Yifei Xing ◽  
Fengyan Zhang ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Measurement ◽  
Research Perspective ◽  
Frequency Measurements ◽  
High Frequency Response ◽  
Lithology Identification ◽  
New Findings ◽  
High Efficient ◽  
Drilling Cost

High-frequency measurements can provide much more new insights for drillstring dynamics compared to traditional instruments, leading to a new realm of understanding of drillstring behaviors in great detail than before. In this paper, data acquisition tools with high-frequency sample rates and the data processing are introduced. Based on high-frequency data, progress of drilling dynamics is summarized, including new understandings of low-frequency drillstring dynamics, high-frequency torsional oscillations (HFTOs), and high-frequency axial oscillations (HFAOs) and new findings for the coupling of vibrations and motions, as well as models and simulation methods to deeply comprehend high-frequency dynamics of drillstring. High-frequency measurements have been used for enabling drillers to improve drill performance, especially for field decision making, BHA selection, and bit design, usually through the ways of minimizing vibrations to obtain high-efficient drilling conditions, the high-frequency response near bit can also be used for lithology identification during drilling. Though there still exists a gap between research perspective and drilling practice, the industry of high-frequency measurements has gotten off a good start, which has huge potential to avoid nonproductive time thereupon reducing drilling cost in the future.

PRODUCTION AND FREQUENCY MEASUREMENT OF CURRENTS HAVING FREQUENCIES FROM 10 TO 100 CYCLES PER SECOND

1938 ◽  
Vol 16a (9) ◽  
pp. 183-189
Author(s):  
A. L. Clark ◽  
L. Katz
Keyword(s):  
Power Output ◽  
Low Frequency ◽  
Frequency Measurement ◽  
Synchronous Motor ◽  
Frequency Measurements ◽  
The Stability

A low frequency dynatron oscillator with a range of 10 to 100 cycles per sec. and a power output of 10 watts is described. The frequency is measured by taking photographs, at intervals of one second, of two pointers on a small synchronous motor powered by the current whose frequency is to be measured. The stability of the oscillations and the accuracy of the frequency measurements are such that frequencies may be maintained and measured to 1 part in 30,000, over a period of several hours.

Hydrogen sulphide emission from two large pig-finishing buildings with long-term high-frequency measurements

2002 ◽  
Vol 138 (2) ◽  
pp. 227-236 ◽  
Author(s):  
J.-Q. NI ◽  
A. J. HEBER ◽  
T. T. LIM ◽  
C. A. DIEHL ◽  
R. K. DUGGIRALA ◽  
...  
Keyword(s):  
Hydrogen Sulphide ◽  
High Frequency ◽  
Frequency Measurement ◽  
Ventilation Rate ◽  
Air Pollutant ◽  
Frequency Measurements ◽  
Sulphide Concentration ◽  
Building Ventilation ◽  
Ventilation Rates

Hydrogen sulphide (H2S) is a common toxic air pollutant and is emitted from decomposing manure at animal facilities. However, there have been only a few studies of H2S emissions from animal buildings, especially those involving long-term, high-frequency measurements. In the current study, H2S emissions from two, 1000-head pig-finishing buildings in Illinois, USA, were monitored with a high-frequency measurement system for 6 months in 1997 during two, partial, pig-growth cycles. Air sample streams were continuously taken from the pit headspace, and the pit and wall fan exhaust air. Hydrogen sulphide concentration was measured at each location with H2S converters and sulphur dioxide (SO2) analysers during 16 or 24 sampling cycles per day, resulting in 4544 sampling cycles and 219 days of reliable data. Building ventilation rate was the summation of pit fan and wall fan airflow rates. Airflow rates of the underfloor manure pit fans were measured directly with full-size impeller anemometers or calculated from airflow/voltage relationships of the fans. Airflow rates of the wall fans were calculated from fan operation and differential static pressure data and fan performance curves. Mean H2S emission was 0·59 kg/day per building, 0·74 g/day per m2 of pit surface area, or 6·3 g/day per animal unit (AU = 500 kg animal weight). The determination of H2S emission per AU was restricted to 193 days when building occupancy was at least 700 pigs per building. Higher temperatures and building ventilation rates resulted in significantly higher H2S emissions per AU.

scholarly journals A New Robust Adaptive Fusion Method for Double-Modality Medical Image PET/CT

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Tao Zhou ◽  
Huiling Lu ◽  
Fuyuan Hu ◽  
Hongbin Shi ◽  
Shi Qiu ◽  
...  
Keyword(s):  
High Frequency ◽  
Medical Image ◽  
Low Frequency ◽  
Frequency Measurement ◽  
Fusion Method ◽  
Fusion Image ◽  
Pet Ct ◽  
Adaptive Fusion ◽  
Robust Adaptive ◽  
Activity Measure

A new robust adaptive fusion method for double-modality medical image PET/CT is proposed according to the Piella framework. The algorithm consists of the following three steps. Firstly, the registered PET and CT images are decomposed using the nonsubsampled contourlet transform (NSCT). Secondly, in order to highlight the lesions of the low-frequency image, low-frequency components are fused by pulse-coupled neural network (PCNN) that has a higher sensitivity to featured area with low intensities. With regard to high-frequency subbands, the Gauss random matrix is used for compression measurements, histogram distance between the every two corresponding subblocks of high coefficient is employed as match measure, and regional energy is used as activity measure. The fusion factor d is then calculated by using the match measure and the activity measure. The high-frequency measurement value is fused according to the fusion factor, and high-frequency fusion image is reconstructed by using the orthogonal matching pursuit algorithm of the high-frequency measurement after fusion. Thirdly, the final image is acquired through the NSCT inverse transformation of the low-frequency fusion image and the reconstructed high-frequency fusion image. To validate the proposed algorithm, four comparative experiments were performed: comparative experiment with other image fusion algorithms, comparison of different activity measures, different match measures, and PET/CT fusion results of lung cancer (20 groups). The experimental results showed that the proposed algorithm could better retain and show the lesion information, and is superior to other fusion algorithms based on both the subjective and objective evaluations.

FREQUENCY-TUNABLE DUAL-BAND PRINTED ANTENNA EQUIPPED WITH COAXIALSPLIT BALANCING UNIT

2019 ◽  
pp. 60-64
Author(s):  
S. A. Alekseytsev ◽  
A. P. Gorbachev
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Dipole Antenna ◽  
Dual Band ◽  
Radiation Characteristics ◽  
High Frequency Response ◽  
Maximum Value ◽  
Linear Behavior ◽  
Lumped Elements ◽  
Frequency Tunable

In this paper, we present initial design of dual-band dipole antenna which able to perform when shifting high frequency band by inserting of inductive element between high-, and low-frequency dipole arms. Responses of high frequency and bandwidth at –10 dB level on the inductivity are presented in the paper. The maximum value of inductivity to be inserted is about hundreds of nH, hence, it can be implemented by microstrip lines. It is also possible to use lumped elements. Approximations of such responses with polynomials power two and lower are presented in the paper. It is shown, that the bandwidth of the S11 below –10 dB high frequency response has approximately linear behavior, so that can be used when carrying out experimental verifying of the numerical simulations. When simulating radiation characteristics the Russian standard FAF‑4D substrate was used, which can operate at frequencies up to 8–10 GHz.

Nonlinear behaviour of the Mack mode in a hypersonic boundary layer

2019 ◽  
Vol 872 ◽  
pp. 74-99 ◽  
Author(s):  
Stuart A. Craig ◽  
Raymond A. Humble ◽  
Jerrod W. Hofferth ◽  
William S. Saric
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
Low Frequency ◽  
Nonlinear Behaviour ◽  
Hypersonic Boundary Layer ◽  
Bispectral Analysis ◽  
Frequency Wave ◽  
Number Range ◽  
High Frequency Response ◽  
Quadratic Phase

Mack-mode waves are measured in a hypersonic boundary layer using high-frequency focusing schlieren deflectometry. Experiments are performed using a $5^{\circ }$ flared cone at $0^{\circ }$ angle of attack in the low-disturbance Mach 6 Quiet Tunnel at Texas A&M University across a free-stream unit Reynolds number range of $7.8\times 10^{6}~\text{m}^{-1}\leqslant \mathit{Re}^{\prime }\leqslant 11.0\times 10^{6}~\text{m}^{-1}$. The high-frequency response of the measurement system allows harmonics and other nonlinear behaviour to be measured. Mack-mode waves and several harmonics are clearly observed at a frequency of $f_{0}\approx 250~\text{kHz}$. Bispectral analysis is used to show that these waves undergo several quadratic phase-coupled sum and difference interactions with themselves to produce harmonics, as well interact with a relatively low-frequency wave that results in amplitude modulation. Bispectral analysis is used to highlight these interactions.

A hybrid method for broadband vibroacoustic simulations

2021 ◽  
Vol 263 (4) ◽  
pp. 2812-2821
Author(s):  
Jared Miller ◽  
Scott D. Sommerfeldt ◽  
Jonathan D. Blotter ◽  
David C. Copley
Keyword(s):  
Hybrid Method ◽  
High Frequency ◽  
Low Frequency ◽  
Energy Response ◽  
High Frequency Response ◽  
Modal Response ◽  
Listening Tests ◽  
Limited Frequency ◽  
Acoustic Responses ◽  
Vibrating Systems

Many methods for simulating acoustic responses of vibrating systems are only suitable for limited frequency ranges, providing either an accurate low frequency or high frequency response. A hybrid method is presented to combine a low frequency modal response and a high frequency statistical energy response to obtain a unified broadband response. The method is designed to produce an auralizable response. An experimental setup is used to validate the method. Listening tests are conducted to assess the realism of the auralizations compared to measurements. The listening tests confirm that the method is able to produce realistic auralizations, subject to a few limitations.

Vibration Mitigation With a Multi-Axial Magnetorheological Mount

2009 ◽  
Author(s):  
Walter Anderson ◽  
The Nguyen ◽  
Mohammad Elahinia
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Low Frequency ◽  
Hybrid Vehicles ◽  
Experimental Results ◽  
Small Displacement ◽  
Frequency Range ◽  
Mr Fluid ◽  
High Frequency Response ◽  
Hydraulic Hybrid

This paper presents a multi-axial magnetorheological (MMR) mount. An MMR mount has been developed for use with hydraulic hybrid vehicles (HHV). Like hybrid electric vehicles (HEV), HHV provides better fuel economy. An inherent problem to hydraulic hybrid vehicles is vibration of the hydraulic pump-motor (P/M). This vibration can be classified as shock loading for initial start-up, and periodic vibration over a large frequency range. The latter vibration opportunity can be classified as having large displacement at low frequency and small displacement at high frequency. This requires a stiff mount for the low frequency response and a soft mount for the high frequency response. A single axis magnetorheological (MR) mount has previously been developed and studied by the same group. This was done to develop an understanding of the MR fluid and to discover the limitations of such a mount. Models to predict the experimental results have also been generated. These models show a good correlation to the experimental results. Then, the model has been enhanced from the single axis mount to a multi-axial. This was done by examining the 3-D CAD model to develop the different boundary conditions for the simulation. With a multi-axial magnetorheological mount, damping and stiffness can be altered to yield acceptable transmissibility over the frequency range. This is achieved through the use of an inertia track paired with a pseudo-decoupler. These features are commonly found in a passive hydraulic mount; however through the use of MR fluid, the downfalls of the hydraulic mount can be mitigated, e.g. performance deterioration outside of notch frequency. Additionally, a magnetorheological mount is semi-active so there is an inherent stability to the mount. The MMR mount uses elastomer and MR fluid to achieve the static stiffness to support the P/M and achieve low dynamic stiffness for the high frequency response, which is necessary for a good isolator. The advantages of the use of a multi-axial magnetorheological mount are as follows: fewer mounts are required, stability when compared to an active mount, less power required when compared to an active mount, better isolation when compared to pure elastomeric and passive hydraulic mounts. A model for a multi-axial magnetorheological mount has been developed and simulated. For the purposes of this study, elastomer has been considered to have a linear dynamic response. Additionally, the shock response of the mount has not been considered. Future work includes manufacturing a multi-axial MR mount to verify the simulation results.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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