scholarly journals Design optimisation of permanently installed monitoring system for polycrystalline materials

2020 ◽  
pp. 147592172095019
Author(s):  
Yuan Liu ◽  
Peter B. Nagy ◽  
Peter Cawley
Keyword(s):  
Surface Area ◽  
Monitoring System ◽  
Signal To Noise Ratio ◽  
Coarse Grained ◽  
Polycrystalline Materials ◽  
Depth Range ◽  
Bulk Wave ◽  
Signal To Noise ◽  
Trade Off ◽  
Noise Ratio

This article presents a design procedure for structural health monitoring systems based on bulk wave ultrasonic sensors for structures fabricated from polycrystalline materials. When designing a monitoring system, maximum coverage per transducer is a general requirement in order for the system to be economic. For coarse-grained polycrystalline materials, monitoring is often made challenging by low signal-to-noise ratios caused by grain scattering. Therefore, when designing a monitoring system for these materials, in addition to the economic requirement, it needs to be ensured that an adequate signal-to-noise ratio can be obtained throughout the monitoring volume. This typically introduces a trade-off between volume coverage per transducer and sensitivity that must be investigated. In this article, this trade-off is studied and a methodology using signal-to-noise maps is presented to design the system, that is, choose the optimal transducer parameters and placement. First, a combined analytical and numerical approach is used to generate a signal-to-noise map. Then, the influence of various factors on signal-to-noise ratio is investigated. Finally, two representative examples, with different criteria, are given to illustrate the methodology. In one example, the full surface area of the testpiece is covered with transducers and the optimum gives the deepest coverage. The other one aims to achieve the minimum fractional surface area that has to be covered with transducers to monitor a narrow depth range far from the surface, which has a potential application in weld monitoring. Results show that the optimum is likely to be at much lower frequency than typically used in inspection, as tracking signals with time gives sensitivity gains. Experiments were carried out to illustrate that higher volume coverage can be obtained at lower frequencies.

Super-resolution methods in MRI: Can they improve the trade-off between resolution, signal-to-noise ratio, and acquisition time?

2012 ◽  
Vol 68 (6) ◽  
pp. 1983-1993 ◽  
Author(s):  
Esben Plenge ◽  
Dirk H. J. Poot ◽  
Monique Bernsen ◽  
Gyula Kotek ◽  
Gavin Houston ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Super Resolution ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Trade Off ◽  
Noise Ratio

scholarly journals Detection of Endo-epicardial Asynchrony in the Atrial Wall Using One-Sided Unipolar and Bipolar Electrograms

2021 ◽  
Author(s):  
Lisette J. M. E. van der Does ◽  
Roeliene Starreveld ◽  
Rohit K. Kharbanda ◽  
Paul Knops ◽  
Charles Kik ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Surface Area ◽  
Signal To Noise Ratio ◽  
Right Atrial ◽  
Signal To Noise ◽  
Atrial Wall ◽  
Noise Ratio ◽  
Unipolar Electrograms

AbstractEndo-epicardial asynchrony (EEA) is a new mechanism possibly maintaining atrial fibrillation. We aimed to determine the sensitivity and best recording modus to detect EEA on electrograms recorded from one atrial side using electrogram fractionation. Simultaneously obtained right atrial endo- and epicardial electrograms from 22 patients demonstrating EEA were selected. Unipolar and (converted) bipolar electrograms were analyzed for presence and characteristics of fractionation corresponding to EEA. Sensitivity of presence of EEA corresponding fractionation was high in patients (86–96%) and moderately high (65–78%) for the asynchronous surface area for unipolar and bipolar electrograms equally. In bipolar electrograms, signal-to-noise ratio of EEA corresponding fractionation decreased and additional fractionation increased for electrograms recorded at the endocardium. Sensitivity of fractionation corresponding to EEA is high for both unipolar and bipolar electrograms. Unipolar electrograms are more suited for detection of EEA due to a larger signal-to-noise ratio and less disturbance of additional fractionation. Graphical Abstract

scholarly journals A New Method to Estimate Peak Signal to Noise Ratio for Least Significant Bit Modification Audio Steganography

2022 ◽  
Vol 30 (1) ◽  
pp. 497-511
Author(s):  
Muhammad Harith Noor Azam ◽  
Farida Ridzuan ◽  
M Norazizi Sham Mohd Sayuti
Keyword(s):  
Signal To Noise Ratio ◽  
High Capacity ◽  
Least Significant Bit ◽  
Early Assessment ◽  
Signal To Noise ◽  
Trade Off ◽  
Audio Steganography ◽  
Early Evaluation ◽  
Noise Ratio ◽  
Different Levels

Audio steganography is implemented based on three main features: capacity, robustness, and imperceptibility, but simultaneously implementing them is still a challenge. Embedding data at the Least Significant Bit (LSB) of the audio sample is one of the most implemented audio steganography methods because the method will give high capacity and imperceptibility. However, LSB has the lowest robustness among all common methods in audio steganography. To cater to this problem, researchers increased the depth of the embedding level from fourth to sixth and eighth LSB level to improve its robustness feature. However, consequently, the imperceptibility feature, which is commonly measured by Peak Signal to Noise Ratio (PSNR), is reduced due to the trade-off between imperceptibility and robustness. Currently, the lack of study on the estimation of the PSNR for audio steganography has caused the early assessment of the imperceptibility-robustness trade-off difficult. Therefore, a method to estimate PSNR, known as PSNR Estimator (PE), is introduced to enable early evaluation of imperceptibility feature for each stego-file produced by the audio steganography, which is important for the utilisation of embedding. The proposed PE estimates the PSNR based on the pattern collected from the embedment at different levels. From the evaluation, the proposed method has 99.9% of accuracy in estimating PSNR values at different levels. In comparison with the Mazdak Method, the proposed method performs better in all situations. In conclusion, the proposed PE can be used as a reference for embedding and further reducing the calculation complexity in finding the feasible value to minimise the trade-off between robustness and imperceptibility.

scholarly journals Evaluating strategies for estimation of local kinematic parameters in noisy land data: quality versus performance trade-offs

2021 ◽  
Vol 18 (6) ◽  
pp. 890-907
Author(s):  
Andrey Bakulin ◽  
Ilya Silvestrov ◽  
Maxim Protasov
Keyword(s):  
Data Quality ◽  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Computational Cost ◽  
Point Sources ◽  
Estimation Methods ◽  
Signal To Noise ◽  
Near Surface ◽  
Trade Off ◽  
Noise Ratio

Abstract Modern land seismic data are typically acquired using high spatial trace density with small source and receiver arrays or point sources and sensors. These datasets are challenging to process due to their massive size and relatively low signal-to-noise ratio caused by scattered near-surface noise. Therefore, prestack data enhancement becomes a critical step in the processing flow. Nonlinear beamforming had proved very powerful for 3D land data. However, it requires computationally intensive estimations of local coherency on dense spatial/temporal grids in 3D prestack data cubes. We present an analysis of various estimation methods focusing on a trade-off between computational efficiency and enhanced data quality. We demonstrate that the popular sequential «2 + 2 + 1» scheme is highly efficient but may lead to unreliable estimation and poor enhancement for data with a low signal-to-noise ratio. We propose an alternative algorithm called «dip + curvatures» that remains stable for such challenging data. We supplement the new strategy with an additional interpolation procedure in spatial and time dimensions to reduce the computational cost. We demonstrate that the «dip + curvatures» strategy coupled with an interpolation scheme approaches the «2 + 2 + 1» method's efficiency while it significantly outperforms it in enhanced data quality. We conclude that the new algorithm strikes a practical trade-off between the performance of the algorithm and the quality of the enhanced data. These conclusions are supported by synthetic and real 3D land seismic data from challenging desert environments with complex near surface.

scholarly journals Structured illumination microscopy with noise-controlled image reconstructions

2021 ◽  
Author(s):  
Carlas S. Smith ◽  
Johan A. Slotman ◽  
Lothar Schermelleh ◽  
Nadya Chakrova ◽  
Sangeetha Hari ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Resolving Power ◽  
Noise Model ◽  
Physical Parameters ◽  
Structured Illumination ◽  
Reconstruction Algorithms ◽  
Structured Illumination Microscopy ◽  
Signal To Noise ◽  
Trade Off ◽  
Noise Ratio

AbstractSuper-resolution structured illumination microscopy (SIM) has become a widely used method for biological imaging. Standard reconstruction algorithms, however, are prone to generate noise-specific artefacts that limit their applicability for lower signal-to-noise data. Here, we present a physically realistic noise model that explains the structured noise artefact and that is used to motivate new complementary reconstruction approaches. True Wiener-filtered SIM optimizes contrast given the available signal-to-noise ratio, flat-noise SIM fully overcomes the structured noise artefact while maintaining resolving power. Both methods eliminate ad-hoc user adjustable reconstruction parameters in favour of physical parameters, enhancing objectivity. The new reconstructions point to a trade-off between contrast and a natural noise appearance. This trade-off can be partly overcome by additional notch filtering, but at the expense of a decrease in signal-to-noise ratio. The benefits of the proposed approaches are demonstrated on focal adhesion and tubulin samples in 2D and 3D, and on nano-fabricated fluorescent test patterns.

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