Online Signal Denoising Using Adaptive Stochastic Resonance in Parallel Array and its Application to Acoustic Emission Signals

2021 ◽  
pp. 1-34
Author(s):  
Jinki Kim ◽  
Ryan L. Harne ◽  
Kon-Well Wang
Keyword(s):  
Acoustic Emission ◽  
Stochastic Resonance ◽  
Noise Level ◽  
A Priori ◽  
Optimal Level ◽  
Signal Denoising ◽  
Post Processing ◽  
Parallel Array ◽  
Noisy Input ◽  
Wide Range

Abstract Signal denoising has been significantly explored in various engineering disciplines. In particular, structural health monitoring applications generally aim to detect weak anomaly responses (including acoustic emission) generated by incipient damage, which are easily buried in noise. Among various approaches, stochastic resonance (SR) has been widely adopted for weak signal detection. While many advancements have been focused on identifying useful information from the frequency domain by optimizing parameters in a post-processing environment to activate SR, it often requires detailed information about the original signal a priori, which is hardly assessed from signals overwhelmed by noise. This research presents a novel online signal denoising strategy by utilizing SR in a parallel array of bistable systems. The original noisy input with additionally applied noise is adaptively scaled, so that the total noise level matches the optimal level that is analytically predicted from a generalized model to robustly enhance signal denoising performance for a wide range of input amplitudes that are often not known in advance. Thus, without sophisticated post-processing procedures, the scaling factor is straightforwardly determined by the analytically estimated optimal noise level and the ambient noise level, which is one of the few quantities that can be reliably assessed from noisy signals in practice. Along with numerical investigations that demonstrate the operational principle and the effectiveness of the proposed strategy, experimental validation of denoising acoustic emission signals by employing a bistable Duffing circuit system exemplifies the promising potential of implementing the new approach for enhancing online signal denoising in practice.

scholarly journals An Adaptive Method for Numerical Differentiation of Difficult-to-Compute Functions

2021 ◽  
Vol 24 (2) ◽  
pp. 59-67
Author(s):  
Helii A. Sheludko ◽  
◽  
Serhii V. Ugrimov ◽  
Keyword(s):  
Optimization Problems ◽  
Initial Conditions ◽  
Special Functions ◽  
A Priori ◽  
Numerical Differentiation ◽  
Adaptive Method ◽  
Optimal Level ◽  
Rate Of Change ◽  
Wide Range ◽  
Equidistant Nodes

An adaptive approach to the numerical differentiation of difficult-to-compute functions is considered. Complex dependencies, which are the result of multiple superpositions of functions or the product of various algorithmic processes, are knowingly difficult to study directly. To establish the nature of the behavior of such dependencies, one has to resort to numerical analysis. One of the important characteristics of functions is a derivative, which indicates the direction and rate of change of a dependence. However, with difficult-to-compute functions, the available a priori information is not always sufficient to achieve the appropriate accuracy of the solution by known means. The loss of accuracy occurs due to the accumulation of round-off errors that grow in proportion to the number of calculated values of a function. In this case, it is necessary to pass on to the posterior approach in order to determine the behavior of the function and move away from the scheme of equidistant nodes, relying on an adaptive way of studying the local situation in the domain of the function. This paper implements an adaptive method for finding derivatives of a function with a minimum of restrictive requirements for the class of functions and the form of their assignment. Due to this, the costs of calculating the function have been significantly reduced with the result that their number has been brought to almost the optimal level. At the same time, the amount of RAM used has sharply decreased. There is no need for a preliminary analysis of the problem of establishing the class of the function under study, in the involvement of special functions or transformation of initial conditions for using standard tables of weight coefficients, etc. For research, it is enough to assign a continuous and bounded function on a fixed segment and a minimum step, which is indirectly responsible for ensuring the required accuracy of differentiation. The effectiveness of the proposed method is demonstrated on a number of test examples. The developed method can be used in more complex problems, for example, in solving some types of differential and integral equations, as well as for a wide range of optimization problems in a wide variety of areas of applied analysis and synthesis.

scholarly journals A Systematic Review and Qualitative Synthesis Resulting in a Typology of Elementary Classroom Movement Integration Interventions

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Spyridoula Vazou ◽  
Collin A. Webster ◽  
Gregory Stewart ◽  
Priscila Candal ◽  
Cate A. Egan ◽  
...  
Keyword(s):  
Physical Activity ◽  
Teacher Collaboration ◽  
A Priori ◽  
Real Life ◽  
Dose Intensity ◽  
Routine Practice ◽  
Qualitative Synthesis ◽  
Wide Range ◽  
Meta Analyses ◽  
Movement Integration

Abstract Background/Objective Movement integration (MI) involves infusing physical activity into normal classroom time. A wide range of MI interventions have succeeded in increasing children’s participation in physical activity. However, no previous research has attempted to unpack the various MI intervention approaches. Therefore, this study aimed to systematically review, qualitatively analyze, and develop a typology of MI interventions conducted in primary/elementary school settings. Subjects/Methods Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to identify published MI interventions. Irrelevant records were removed first by title, then by abstract, and finally by full texts of articles, resulting in 72 studies being retained for qualitative analysis. A deductive approach, using previous MI research as an a priori analytic framework, alongside inductive techniques were used to analyze the data. Results Four types of MI interventions were identified and labeled based on their design: student-driven, teacher-driven, researcher-teacher collaboration, and researcher-driven. Each type was further refined based on the MI strategies (movement breaks, active lessons, other: opening activity, transitions, reward, awareness), the level of intrapersonal and institutional support (training, resources), and the delivery (dose, intensity, type, fidelity). Nearly half of the interventions were researcher-driven, which may undermine the sustainability of MI as a routine practice by teachers in schools. An imbalance is evident on the MI strategies, with transitions, opening and awareness activities, and rewards being limitedly studied. Delivery should be further examined with a strong focus on reporting fidelity. Conclusions There are distinct approaches that are most often employed to promote the use of MI and these approaches may often lack a minimum standard for reporting MI intervention details. This typology may be useful to effectively translate the evidence into practice in real-life settings to better understand and study MI interventions.

scholarly journals Handheld versus mounted laser speckle contrast perfusion imaging demonstrated in psoriasis lesions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ata Chizari ◽  
Mirjam J. Schaap ◽  
Tom Knop ◽  
Yoeri E. Boink ◽  
Marieke M. B. Seyger ◽  
...  
Keyword(s):  
Perfusion Imaging ◽  
Laser Speckle ◽  
Psoriatic Skin ◽  
Post Processing ◽  
Speed Of Light ◽  
Contrast Imaging ◽  
Speckle Contrast ◽  
Frame Alignment ◽  
Wide Range ◽  
Perfusion Maps

AbstractEnabling handheld perfusion imaging would drastically improve the feasibility of perfusion imaging in clinical practice. Therefore, we examine the performance of handheld laser speckle contrast imaging (LSCI) measurements compared to mounted measurements, demonstrated in psoriatic skin. A pipeline is introduced to process, analyze and compare data of 11 measurement pairs (mounted-handheld LSCI modes) operated on 5 patients and various skin locations. The on-surface speeds (i.e. speed of light beam movements on the surface) are quantified employing mean separation (MS) segmentation and enhanced correlation coefficient maximization (ECC). The average on-surface speeds are found to be 8.5 times greater in handheld mode compared to mounted mode. Frame alignment sharpens temporally averaged perfusion maps, especially in the handheld case. The results show that after proper post-processing, the handheld measurements are in agreement with the corresponding mounted measurements on a visual basis. The absolute movement-induced difference between mounted-handheld pairs after the background correction is $$16.4\pm 9.3~\%$$ 16.4 ± 9.3 % (mean ± std, $$n=11$$ n = 11 ), with an absolute median difference of $$23.8\%$$ 23.8 % . Realization of handheld LSCI facilitates measurements on a wide range of skin areas bringing more convenience for both patients and medical staff.

Applications of 3D printing in critical care medicine: A scoping review

2021 ◽  
pp. 0310057X2097665
Author(s):  
Natasha Abeysekera ◽  
Kirsty A Whitmore ◽  
Ashvini Abeysekera ◽  
George Pang ◽  
Kevin B Laupland
Keyword(s):  
Critical Care ◽  
Scoping Review ◽  
A Priori ◽  
Three Dimensional ◽  
Critical Care Medicine ◽  
Future Research ◽  
Care Practice ◽  
Three Dimensional Printing ◽  
Wide Range ◽  
Dimensional Printing

Although a wide range of medical applications for three-dimensional printing technology have been recognised, little has been described about its utility in critical care medicine. The aim of this review was to identify three-dimensional printing applications related to critical care practice. A scoping review of the literature was conducted via a systematic search of three databases. A priori specified themes included airway management, procedural support, and simulation and medical education. The search identified 1544 articles, of which 65 were included. Ranging across many applications, most were published since 2016 in non – critical care discipline-specific journals. Most studies related to the application of three-dimensional printed models of simulation and reported good fidelity; however, several studies reported that the models poorly represented human tissue characteristics. Randomised controlled trials found some models were equivalent to commercial airway-related skills trainers. Several studies relating to the use of three-dimensional printing model simulations for spinal and neuraxial procedures reported a high degree of realism, including ultrasonography applications three-dimensional printing technologies. This scoping review identified several novel applications for three-dimensional printing in critical care medicine. Three-dimensional printing technologies have been under-utilised in critical care and provide opportunities for future research.

LOW-NOISE SILICON-ON-INSULATOR HALL DEVICES

2004 ◽  
Vol 04 (02) ◽  
pp. L345-L354 ◽  
Author(s):  
Y. HADDAB ◽  
V. MOSSER ◽  
M. LYSOWEC ◽  
J. SUSKI ◽  
L. DEMEUS ◽  
...  
Keyword(s):  
Noise Level ◽  
Low Voltage ◽  
Silicon Layer ◽  
Electrical Current ◽  
Low Noise ◽  
Silicon On Insulator ◽  
Technological Parameters ◽  
Wide Range ◽  
Hall Sensors ◽  
Soi Technology

Hall sensors are used in a very wide range of applications. A very demanding one is electrical current measurement for metering purposes. In addition to high precision and stability, a sufficiently low noise level is required. Cost reduction through sensor integration with low-voltage/low-power electronics is also desirable. The purpose of this work is to investigate the possible use of SOI (Silicon On Insulator) technology for this integration. We have fabricated SOI Hall devices exploring the useful range of silicon layer thickness and doping level. We show that noise is influenced by the presence of LOCOS and p-n depletion zones near the edges of the active zones of the devices. A proper choice of SOI technological parameters and process flow leads to up to 18 dB reduction in Hall sensor noise level. This result can be extended to many categories of devices fabricated using SOI technology.

scholarly journals Hierarchical Matching and Regression with Application to Photometric Redshift Estimation

2016 ◽  
Vol 12 (S325) ◽  
pp. 145-155
Author(s):  
Fionn Murtagh
Keyword(s):  
Information Structure ◽  
Data Analytics ◽  
A Priori ◽  
Sloan Digital Sky Survey ◽  
Photometric Redshifts ◽  
Merging Galaxies ◽  
Photometric Redshift ◽  
Sky Survey ◽  
Wide Range ◽  
Regression Problems

AbstractThis work emphasizes that heterogeneity, diversity, discontinuity, and discreteness in data is to be exploited in classification and regression problems. A global a priori model may not be desirable. For data analytics in cosmology, this is motivated by the variety of cosmological objects such as elliptical, spiral, active, and merging galaxies at a wide range of redshifts. Our aim is matching and similarity-based analytics that takes account of discrete relationships in the data. The information structure of the data is represented by a hierarchy or tree where the branch structure, rather than just the proximity, is important. The representation is related to p-adic number theory. The clustering or binning of the data values, related to the precision of the measurements, has a central role in this methodology. If used for regression, our approach is a method of cluster-wise regression, generalizing nearest neighbour regression. Both to exemplify this analytics approach, and to demonstrate computational benefits, we address the well-known photometric redshift or ‘photo-z’ problem, seeking to match Sloan Digital Sky Survey (SDSS) spectroscopic and photometric redshifts.

scholarly journals A Consistent Track-to-Track Fusion Method Based on Copula Theory

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Kelin Lu ◽  
K. C. Chang ◽  
Rui Zhou
Keyword(s):  
Probability Distributions ◽  
A Priori ◽  
Joint Probability ◽  
Network Connectivity ◽  
Consistent Estimate ◽  
Fusion Algorithm ◽  
Copula Theory ◽  
Wide Range ◽  
Primary Advantage ◽  
Joint Probability Distributions

This paper addresses the problem of distributed fusion when the conditional independence assumptions on sensor measurements or local estimates are not met. A new data fusion algorithm called Copula fusion is presented. The proposed method is grounded on Copula statistical modeling and Bayesian analysis. The primary advantage of the Copula-based methodology is that it could reveal the unknown correlation that allows one to build joint probability distributions with potentially arbitrary underlying marginals and a desired intermodal dependence. The proposed fusion algorithm requires no a priori knowledge of communications patterns or network connectivity. The simulation results show that the Copula fusion brings a consistent estimate for a wide range of process noises.

Porosity Control of Thermally Sprayed Ceramic Deposits

1998 ◽  
Author(s):  
P. Chraska ◽  
V. Brozek ◽  
B.J. Kolman ◽  
J. Ilavsky ◽  
K. Neufuss ◽  
...  
Keyword(s):  
Gas Permeability ◽  
Water Immersion ◽  
Thermal Spraying ◽  
Spray Parameters ◽  
Post Processing ◽  
Free Standing ◽  
Spray Process ◽  
Wide Range ◽  
Controlled Porosity ◽  
Selection Of

Abstract Porosity regulates the deposit's properties and therefore methods for its control are of a vital industrial importance. Thermal spraying can produce deposits in a wide range of porosities by selection of a spray process itself, by selection of spray parameters, feedstock size and chemistry, etc. Manufacturing of deposits with controlled porosity may be difficult if the selection of spray processes and materials is limited. Special methods of deposition or/and subsequent post processing may be therefore necessary. These methods are studied in the presented work. All spraying was done with the water-stabilized plasma (WSP®) system PAL 160. Thick deposits and free-standing parts were sprayed from alumina, zircon, metal Al and Ni powders and their combinations. Porosity was characterized by number of techniques such as gas permeability, water immersion, MIP, SEM and SANS. Mechanical properties were characterized by the Young's modulus. Special methods of deposition, such as spraying of mixtures of ceramics and metals were successfully used. Either sandwiched-structures with alternating layers of ceramics and metals were sprayed (for the sealing purpose) or mechanical mixtures of ceramic and metallic feedstock were sprayed. Several post-processing methods were used to change porosity volumes or other materials characteristics. To increase the porosity the metallic phases were subsequently removed by leaching or by annealing at temperatures above the melting point of metal. A number of sealing materials (organic and inorganic) were used to seal the pores by infiltration at ambient or higher pressures. The results show, that significant changes of porosity volume and, especially, of the gas permeability are possible. Another tested method was annealing/calcination of deposits, which resulted in an increase or decrease of porosity, depending on deposit's chemistry and annealing conditions. Results show that all used post processings are capable of significant changes of deposit microstructure and that they may be successfully applied in practice.

Study of Properties of Expanded Graphite – Polymer Porous Composite by Acoustic Emission Method

2013 ◽  
Vol 58 (4) ◽  
pp. 1331-1336 ◽  
Author(s):  
J. Berdowski ◽  
S. Berdowska ◽  
F. Aubry
Keyword(s):  
Acoustic Emission ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Physical And Mechanical Properties ◽  
Expanded Graphite ◽  
Composite Membranes ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Graphite Composite ◽  
Wide Range

Abstract The purpose of this paper was to investigate the physical and mechanical properties of compressed expanded graphite (CEG) and their porous derivatives after impregnation, polymerization; and carbonization by the use of acoustic emission method (AE). The mechanical and structural characteristics of compressed expanded graphite and their three groups of porous composites after each technological process are presented and discussed. The measurements of acoustic emission parameters in these materials were carried out at wide range of frequency of the waves (0.1÷2.5 MHz). The changes of two of parameters: - AE pulses counts rate and spectrum distribution of AE waves - are presented in this paper. The analysis of the respective parameters AE also gives possibility to determine the micro- and macro structural changes of materials at different levels of technological processes. Applications of these materials as catalysts with high specific surface make them very interesting subject of study. Also compressed expanded graphite composite membranes prepared from furfuryl alcohol polymers are promising for gas separation.

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