scholarly journals Analysis of Primary Field Shielding Stability for the Weak Coupling Coil Designs

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 519
Author(s):  
Jiangbo Huang ◽  
Haowen Wang ◽  
Zhihong Fu ◽  
Wei Fu
Keyword(s):  
Weak Coupling ◽  
Signal To Noise Ratio ◽  
Primary Field ◽  
Coil Design ◽  
Key Indicator ◽  
Transient Electromagnetic ◽  
Transmitter Coil ◽  
Conversion Tool ◽  
The Relationship ◽  
Coupling Coil

As an electromagnetic field conversion tool in the transient electromagnetic method (TEM), the weak coupling coils reduce the mutual inductance of its transmitter and receiver coils by special structural optimization, so the detection signal can be protruded from the primary field interference generated by the transmitter coil; thus, this kind of coil design can significantly improve the signal-to-noise ratio. However, with the popularity of drag or aerial TEM exploration, the structural stability problem caused by bumps or windage leads to non-negligible primary field leakages, thereby reducing the detection reliability. This paper incorporates the primary field shielding stability as a key indicator of the weak coupling designs and proposes a calibration scheme for this stability assessment, based on which the shielding stability of five typical weak coupling coil designs is quantitatively compared, and the relationship between the primary field density and the shielding stability explored in this study may contribute to the selection and improvement of TEM coils.

Elimination of mutual inductance effect for small-loop transient electromagnetic devices

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. E143-E154 ◽  
Author(s):  
Zhihong Fu ◽  
Haowen Wang ◽  
Yao Wang ◽  
Nengyi Fu ◽  
Heng-Ming Tai ◽  
...  
Keyword(s):  
Weak Coupling ◽  
Mutual Inductance ◽  
Coil Design ◽  
Détection Signal ◽  
Near Surface ◽  
Loop Design ◽  
Transient Electromagnetic ◽  
Small Loop ◽  
Coupling Coil ◽  
Detection Signal

The transient electromagnetic (TEM) method is a widely used nonintrusive geophysical method for ground exploration. Due to the mutual inductance between the transmitter (TX) coil and the receiver (RX) coil, the primary field generated by the emission current reduces the accuracy of the near-surface detection. Because the feature signal [Formula: see text] carrying the target information is mainly distributed in the early secondary-field response, the expanded detection signal will reduce the near-surface investigation capability of the TEM device due to the following three aspects: the loss of the proportion of [Formula: see text] in the detection signal due to the excessively high primary-field response, the loss of [Formula: see text] due to the clipping loss, and the reduction of the noise margin in the case in which the detection signal is magnified. These problems are particularly significant in small-loop devices due to the tight coil distribution. The mutual inductance can be reduced by adjusting the relative positions of the TX and RX coils, a configuration called the weak-coupling coil design. We have analyzed the design principle of the weak-coupling coil design and developed a new design scheme — the crossing-loop design. Simulation results indicate that the crossing-loop design performs superiorly in terms of the detection sensitivity and the investigation depth, compared with the nonweak-coupling coil design and other weak-coupling coil designs such as the gradient coils, opposing coils, and the bucking coil design. The experimental results indicate that the crossing-loop design provides much better near-surface investigation capability than the central-loop device with the same TX coil, which is a typical nonweak-coupling coil design.

Weak Transient Electromagnetic Radiation Signal Detection Method Considering the New Watershed Image Segmentation Algorithm

2019 ◽  
Vol 34 (03) ◽  
pp. 2054009
Author(s):  
Wenjun Huo ◽  
Peng Chu ◽  
Kai Wang ◽  
Liangting Fu ◽  
Zhigang Niu ◽  
...  
Keyword(s):  
Electromagnetic Radiation ◽  
Cross Correlation ◽  
Detection Efficiency ◽  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Detection Methods ◽  
Signal To Noise ◽  
Long Distance ◽  
Transient Electromagnetic ◽  
Noise Ratio

In order to study the detection methods of weak transient electromagnetic radiation signals, a detection algorithm integrating generalized cross-correlation and chaotic sequence prediction is proposed in this paper. Based on the dual-antenna test and cross-correlation information estimation method, the detection of aperiodic weak discharge signals under low signal-to-noise ratio is transformed into the estimation of periodic delay parameters, and the noise is reduced at the same time. The feasibility of this method is verified by simulation and experimental analysis. The results show that under the condition of low signal-to-noise ratio, the integrated method can effectively suppress the influence of 10 noise disturbances. It has a high detection probability for weak transient electromagnetic radiation signals, and needs fewer pulse accumulation times, which improves the detection efficiency and is more suitable for long-distance detection of weak electromagnetic radiation sources.

Computational Design for Digitally Fabricated 3D Inductive Power Transfer Coils

2022 ◽  
pp. 1-28
Author(s):  
Jun Xu ◽  
Eugeni L. Doubrovski ◽  
Jo Geraedts ◽  
Yu Song
Keyword(s):  
Design Method ◽  
Computational Design ◽  
Future Research ◽  
Receiver Coil ◽  
Power Transfer ◽  
Coil Design ◽  
Optimal Position ◽  
Inductive Power Transfer ◽  
Transmitter Coil ◽  
Inductive Power

Abstract The geometric shapes and the relative position of coils influence the performance of a three-dimensional (3D) inductive power transfer system. In this paper, we propose a coil design method for specifying the positions and the shapes of a pair of coils to transmit the desired power in 3D. Given region of interests (ROIs) for designing the transmitter and the receiver coils on two surfaces, the transmitter coil is generated around the center of its ROI first. The center of the receiver coil is estimated as a random seed position in the corresponding 3D surface. At this position, we use the heatmap method with electromagnetic constraints to iteratively extend the coil until the desired power can be transferred via the set of coils. In each step, the shape of the extension, i.e. a new turn of the receiver coil, is found as a spiral curve based on the convex hulls of adjacent turns in the 2D projection plane along their normal direction. Then, the optimal position of the receiver coil is found by maximizing the efficiency of the system. In the next step, the position and the shape of the transmitter coil are optimized based on the fixed receiver coil using the same method. This zig-zag optimization process iterates until an optimum is reached. Simulations and experiments with digitally fabricated prototypes were conducted and the effectiveness of the proposed 3D coil design method was verified. Possible future research directions are highlighted well.

Lessons Learned … About Curriculum: Five Years on and Half a World Away

2005 ◽  
Vol 24 (2) ◽  
pp. 111-126 ◽  
Author(s):  
Doune Macdonald ◽  
Lisa Hunter
Keyword(s):  
Physical Education ◽  
Lessons Learned ◽  
National Standards ◽  
Primary Field ◽  
Health And Physical Education ◽  
Construction Of Knowledge ◽  
The Social ◽  
Social Construction Of Knowledge ◽  
The Relationship ◽  
Selection Of

The knowledge, skills, and attitudes manifested in health and physical education school curricula are an arbitrary selection of that which is known and valued at a particular place and time. Bernstein’s (2000) theories of the social construction of knowledge offer a way to better understand the relationship between the production, selection, and reproduction of curricular knowledge. This article overviews contemporary knowledge in the primary field (production) upon which curriculum writers in the recontextualizing field may draw. It highlights tensions in the knowledge generated within the primary field and, using a case of the USA’s National Standards for Physical Education (NASPE), demonstrates how particular discourses become privileged when translated into curriculum documents in the recontextualizing field.

scholarly journals Methods of Controlling Lift - off in Conductivity Invariance Phenomenon for Eddy Current Testing

2020 ◽  
Author(s):  
Zhongwen Jin ◽  
Yuwei Meng ◽  
Rongdong Yu ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Eddy Current ◽  
Coating Thickness ◽  
Test Sample ◽  
Common Point ◽  
Coil Design ◽  
Current Testing ◽  
Lift Off ◽  
Two Parameters ◽  
The Relationship

<p>Previously, a conductivity invariance phenomena (CIP) has been discovered – at a certain lift-off, the inductance change of the sensor due to a test sample is immune to conductivity variations, i.e. the inductance – lift-off curve passes through a common point at a certain lift-off, termed as conductivity invariance lift-off. However, this conductivity invariance lift-off is fixed for a particular sensor setup, which is not convenient for various sample conditions. In this paper, we propose using two parameters in the coil design – the horizontal and vertical distances between the transmitter and the receiver to control the conductivity invariance lift-off. The relationship between these two parameters and the conductivity invariance lift-off is investigated by simulation and experiments and it has been found that there is an approximate linear relationship between these two parameters and the conductivity invariance lift-off. This is useful for applications where the measurements have restrictions on lift-off, e.g. uneven coating thickness which limits the range of the lift-off of probe during the measurements. Therefore, based on this relationship, it can be easier to adjust the configuration of the probe for a better inspection of the test samples.</p>

Review of Recent Research on the Selection of Frequency-Gain Characteristics for Hearing Aids

1980 ◽  
Vol 89 (5_suppl) ◽  
pp. 79-83
Author(s):  
Richard Lippmann
Keyword(s):  
Hearing Aids ◽  
Speech Intelligibility ◽  
Signal To Noise Ratio ◽  
Hearing Aid ◽  
Linear Amplification ◽  
Percentage Points ◽  
Gain Characteristic ◽  
The Relationship ◽  
Fitting Hearing Aids ◽  
Selection Of

Following the Harvard master hearing aid study in 1947 there was little research on linear amplification. Recently, however, there have been a number of studies designed to determine the relationship between the frequency-gain characteristic of a hearing aid and speech intelligibility for persons with sensorineural hearing loss. These studies have demonstrated that a frequency-gain characteristic that rises at a rate of 6 dB/octave, as suggested by the Harvard study, is not optimal. They have also demonstrated that high-frequency emphasis of 10–40 dB above 500–1000 Hz is beneficial. Most importantly, they have demonstrated that hearing aids as they are presently being fit do not provide maximum speech intelligibility. Percent word correct scores obtained with the best frequency-gain characteristics tested in various studies have been found to be 9 to 19 percentage points higher than scores obtained with commercial aids owned by subjects. This increase in scores is equivalent to an increase in signal-to-noise ratio of 10 to 20 dB. This is a significant increase which could allow impaired listeners to communicate in many situations where they presently cannot. These results demonstrate the need for further research on linear amplification aimed at developing practical suggestions for fitting hearing aids.

scholarly journals IMPROVED BUCKING COIL DESIGN IN HELICOPTER TRANSIENT ELECTROMAGNETIC SYSTEM

2017 ◽  
Vol 60 ◽  
pp. 131-139 ◽  
Author(s):  
Pan Xiao ◽  
Zongyang Shi ◽  
Xin Wu ◽  
Guangyou Fang
Keyword(s):  
Coil Design ◽  
Electromagnetic System ◽  
Transient Electromagnetic

Research on the Frequency Spectrum Management Method of VLF Based on the Propagation Prediction Technology

2014 ◽  
Vol 543-547 ◽  
pp. 2180-2183 ◽  
Author(s):  
Jian Ping Zhou ◽  
Guang Ming Li
Keyword(s):  
Signal To Noise Ratio ◽  
Effective Means ◽  
Spectrum Management ◽  
Predicting Model ◽  
Atmospheric Noise ◽  
Communication Frequency ◽  
Propagation Prediction ◽  
Noise Statistics ◽  
Relationship Of ◽  
The Relationship

VLF communication is one of the most effective means to command underwater platform. The spectrum resource of vlf communication is limited, so it is very important for enhance the reliability of vlf communication to strengthen the vlf communication spectrum management. It makes use of the well prediction of the vlf frequency band, to establish the signal field predicting model and atmospheric noise statistics predicting model respectively, predicts the field of signal and noise level, and then calculated the signal-to-noise ratio (SNR). According to the SNR distribution we can determine the relationship of the optimal communication frequency, time and location of receiver. So the efficiency of spectrum management for vlf communication can be enhanced.

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