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KALAJE, Abdulfatah, and Hasan DEMİR. "EEG Sinyallerinde Wavelet Dönüşümü ve CNN ile Duygu Tanıma." MAS Journal of Applied Sciences 10, no. 1 (2025): 81–89. https://doi.org/10.5281/zenodo.15088482.
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Bu çalışmada farklı Wavelet Dönüşümü yöntemleri kullanılmıştır. Wavelet Dönüşümü katsayıları kullanılarak edilen öznitelikler ile yapay sinir ağları ve konvolüsyonel sinir ağları kullanılarak EEG sinyallerinde duygu tanıma yapılmıştır. Dört kişiden alınan üç farklı duyguya ait EEG sinyallerine ait dataseti kullanılmıştır. Stresli, nötr ve rahat duyguları sınıflama amacıyla kullanılmıştır. Sürekli wavelet dönüşümü (CWT), 1D ve 2D için ayrık wavelet dönüşümü (DWT) ve senkronize sıkıştırılmış wavelet dönüşümü (SSWT) ile elde edilen sonuçlar karşılaştırılarak EEG sinyallerinde duygu tanıma işlemi için uygun wavelet dönüşümü belirlenmeye çalışılmıştır. Senkronize sıkıştırılmış wavelet dönüşümünün (SSWT) en yüksek doğruluk, kesinlik, duyarlılık, özgüllük ve F1-skoru ile duygu sınıflandırması için en etkili algoritma olduğu görülmüştür.
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Amhar, Fahmi, Endang Purnama Giri, Florence Elfriede Sinthauli Silalahi, et al. "Ownership Protection on Digital Elevation Model (DEM) Using Transform-Based Watermarking." ISPRS International Journal of Geo-Information 11, no. 3 (2022): 200. http://dx.doi.org/10.3390/ijgi11030200.
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This research aims to protect Digital Elevation Model (DEM) data from piracy or counterfeiting. An invisible watermark inserted into the data, which will not considerably change the data value, is necessary. The proposed method involves the use of the two-dimensional discrete cosine transform (2D DCT), a combination of 2D DCT and discrete wavelet transform (DWT), and two-dimensional discrete Fourier transform (2D DFT) in the frequency domain. The data used include a National DEM file downloaded from the geoportal of the Geospatial Information Agency (Badan Informasi Geospasial—BIG). Three files represent mountainous, lowland/urban, and coastal areas. An “attack” is also conducted on the watermarked DEM by cropping. The results indicate that the watermarked DEM is well recognized. The watermark can be read 100% for 2D DCT, while that for 2D DFT can be read 90.50%. The distortion value of the elevation data under the DCT technique demonstrates the smallest maximum value of 0.1 m compared with 4.5 and 1.1 m for 2D DFT and 2D DCT–DWT. Meanwhile, the height difference (Max Delta), the peak signal-to-noise ratio, and the root mean squared error (RMSE) are highest in mountainous, lowland, and coastal areas, respectively. Overall, the 2D DCT is also superior to the 2D DFT and the2D DCT–DWT. Although only one can recognize the nine watermarks inserted on each sheet, DEMs attacked by the cropping process can still be identified. However, this finding can sufficiently confirm that DEMs belong to BIG.
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Medina, Javier, Nelson Vera, and Erika Upegui. "A comparative study for the assessment of Ikonos satellite image-fusion techniques." Indonesian Journal of Electrical Engineering and Computer Science 25, no. 1 (2022): 256. http://dx.doi.org/10.11591/ijeecs.v25.i1.pp256-264.
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I<span>Image-fusion provide users with detailed information about the urban and rural environment, which is useful for applications such as urban planning and management when higher spatial resolution images are not available. There are different image fusion methods. This paper implements, evaluates, and compares six satellite image-fusion methods, namely wavelet 2D-M transform, gram schmidt, high-frequency modulation, high pass filter (HPF) transform, simple mean value, and PCA. An Ikonos image (Panchromatic-PAN and multispectral-MULTI) showing the northwest of Bogotá (Colombia) is used to generate six fused images</span>: MULTI<sub>Wavelet 2D-M</sub>, MULTI<sub>G-S</sub>, MULTI<sub>MHF</sub>, MULTI<sub>HPF</sub>, MULTI<sub>SMV</sub>, and MULTI<sub>PCA</sub>. <span>In order to assess the efficiency of the six image-fusion methods, the resulting images were evaluated in terms of both spatial quality and spectral quality. To this end, four metrics were applied, namely the correlation index, erreur relative globale adimensionnelle de synthese (ERGAS), relative average spectral error (RASE) and the Q index. The best results were obtained for the </span> MULTI<sub>SMV</sub> image, which exhibited spectral correlation higher than 0.85, a Q index of 0.84, and the highest scores in spectral assessment according to ERGAS and RASE, 4.36% and 17.39% respectively.
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Javier, Medina1 2., Vera2 Nelson, and Upegui1 2. Erika. "A comparative study for the assessment of Ikonos satellite image-fusion techniques." Indonesian Journal of Electrical Engineering and Computer Science 25, no. 1 (2022): 256–64. https://doi.org/10.11591/ijeecs.v25.i1.pp256-264.
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Image-fusion provide users with detailed information about the urban and rural environment, which is useful for applications such as urban planning and management when higher spatial resolution images are not available. There are different image fusion methods. This paper implements, evaluates, and compares six satellite image-fusion methods, namely wavelet 2D-M transform, gram schmidt, high-frequency modulation, high pass filter (HPF) transform, simple mean value, and PCA. An Ikonos image (PanchromaticPAN and multispectral-MULTI) showing the northwest of Bogotá (Colombia) is used to generate six fused images: MULTIWavelet 2D-M, MULTIG-S, MULTIMHF, MULTIHPF, MULTISMV, and MULTIPCA. In order to assess the efficiency of the six image-fusion methods, the resulting images were evaluated in terms of both spatial quality and spectral quality. To this end, four metrics were applied, namely the correlation index, erreur relative globale adimensionnelle de synthese (ERGAS), relative average spectral error (RASE) and the Q index. The best results were obtained for the MULTISMV image, which exhibited spectral correlation higher than 0.85, a Q index of 0.84, and the highest scores in spectral assessment according to ERGAS and RASE, 4.36% and 17.39% respectively.
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Osipov, A. V., E. S. Pleshakova, and S. T. Gataullin. "Production processes optimization through machine learning methods based on geophysical monitoring data." Computer Optics 48, no. 4 (2024): 633–42. http://dx.doi.org/10.18287/2412-6179-co-1373.
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The purpose of the article is to create an effective method for low-delay monitoring of the operating state of a drill string and a drill bit without interfering with the proper drilling process. For the drilling process to be continuously controlled, an experimental setup that operates by utilizing the phase-metric method of control was developed. Any movement of the bit causes a change in the electrical characteristics of the probing signal. To obtain a stable signal from a bit immersion depth of up to 250 m, a frequency of probing electrical signals of 166 Hz and an amplitude of up to 500 V were used; the sampling rate of an analog-to-digital converter (ADC) was 10101 Hz. To identify the state of the drill string and the bit based on graphs of time-dependences of changes in the probing signal electrical characteristics, the present authors investigated a number of deep learning methods. Based on the results of the study, a series of capsular neural network methods ( CapsNet ) was chosen. The authors developed modifications of 2D-CapsNet: windowed Fourier transform (WFT) - 2D-CapsNet and frequency slice wavelet transform (FSWT) - 2D-CapsNet. Both of these methods showed a 99% accuracy in determining the transition between two layers of rocks with different properties, which is 2–3% higher than the currently used measurement-while-drilling (MWD) and logging-while-drilling (LWD) rock surveys. Both of these methods unambiguously reveal self-oscillations in the drill string. When determining a fully serviceable bit in the case of self-oscillations, the (FSWT) - 2D-CapsNet method showed an accuracy of 99%.
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Seelam, Naresh Kumar, Thinesh Kumar, Santosh Dhubia, Gangumalla Srinivasa Rao, and Sanjit Kumar Pal. "Enhancing Thin Coal Seam Detection in Eastern Indian Coalfields Using ICWT-Decon-Based Seismic Attributes and Acoustic Impedance Inversion." Minerals 14, no. 9 (2024): 920. http://dx.doi.org/10.3390/min14090920.
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A high-resolution seismic survey (HRSS) is often used in coal exploration to bridge the data gap between two consecutive boreholes and avoid ambiguity in geological interpretation. The application of high-resolution seismic surveys in the Indian context is challenging as the delineation of thin non-coal layers within the coal layer requires a very high seismic data resolution. However, conventional seismic processing techniques fail to resolve thin coal/non-coal layers and faults, which is crucial for the precise estimation of coal resources and mine economics. To address these issues, we applied the inverse continuous wavelet transform deconvolution (ICWT-Decon) technique to post-stack depth-migrated seismic sections. We examined the feasibility of the ICWT-Decon technique in both a synthetic post-stack depth-migrated model and 2D/3D seismic data from the North Karanpura and Talcher Coalfields in Eastern India. The results offered enhanced seismic sections, attributes (similarity and sweetness), and acoustic inversion that aided in the precise positioning of faults and the delineation of a thin non-coal layer of 4.68 m within a 16.7 m coal seam at an approximate depth of 450 m to 550 m. This helped in the refinement of the resource estimation from 74.96 MT before applying ICWT-Decon to 55.92 MT afterward. Overall, the results of the study showed enhancements in the seismic data resolution, the better output of seismic attributes, and acoustic inversion, which could enable more precise lithological and structural interpretation.
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Borisov, Dmitry, Fuchun Gao, Paul Williamson, and Jeroen Tromp. "Application of 2D full-waveform inversion on exploration land data." GEOPHYSICS 85, no. 2 (2020): R75—R86. http://dx.doi.org/10.1190/geo2019-0082.1.
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Estimating subsurface seismic properties is an important topic in civil engineering, oil and gas exploration, and global seismology. We have developed an application of 2D elastic waveform inversion with an active-source on-shore data set, as is typically acquired in exploration seismology on land. The maximum offset is limited to 12 km, and the lowest available frequency is 5 Hz. In such a context, surface waves are generally treated as noise and are removed as a part of data processing. In contrast to the conventional approach, our workflow starts by inverting surface waves to constrain shallow parts of the shear wavespeed model. To mitigate cycle skipping, frequency- and offset-continuation approaches are used. To accurately take into account free-surface effects (and irregular topography), a spectral-element-based wave propagation solver is used for forward modeling. To reduce amplitude influences, a normalized crosscorrelation (NC) objective function is used in conjunction with systematic updates of the source wavelet during the inversion process. As the inversion proceeds, body waves are gradually incorporated in the process. At the final stage, surface and body waves are inverted together using the entire offset range over the band between 5 and 15 Hz. The inverted models include high-resolution features in the first 500 m of compressional and shear wavespeeds, with some model updates down to 4.0 km in the first parameter. The inversion results confirmed by well-log information, indicate a better fit of compressional to shear wavespeeds ratios compared with the initial model. The final data fit is also noticeably improved compared to the initial one. Although our results confirm previous studies demonstrating that an NC norm combined with a source time function correction can partly stabilize purely elastic inversions of viscoelastic data, we believe that including an attenuation depth model in the forward simulation gives better results.
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Wang, Yi, Xueyi Shang, and Kang Peng. "Locating Mine Microseismic Events in a 3D Velocity Model through the Gaussian Beam Reverse-Time Migration Technique." Sensors 20, no. 9 (2020): 2676. http://dx.doi.org/10.3390/s20092676.
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Microseismic (MS) source location is a fundamental and critical task in mine MS monitoring. The traditional ray tracing-based location method can be easily affected by many factors, such as multi-ray path effects, waveform focusing and defocusing of wavefield propagation, and low picking precision of seismic phase arrival. By contrast, the Gaussian beam reverse-time migration (GBRTM) location method can effectively and correctly model the influences of multi-path effects and wavefield focusing and defocusing in complex 3D media, and it takes advantages of the maximum energy focusing point as the source location with the autocorrelation imaging condition, which drastically reduces the requirements of signal-to-noise ratio (SNR) and picking accuracy of P-wave arrival. The Gaussian beam technique has been successfully applied in locating natural earthquake events and hydraulic fracturing-induced MS events in one-dimensional (1D) or simple two-dimensional (2D) velocity models. The novelty of this study is that we attempted to introduce the GBRTM technique into a mine MS event location application and considered utilizing a high-resolution tomographic 3D velocity model for wavefield back propagation. Firstly, in the synthetic test, the GBRTM location results using the correct 2D velocity model and different homogeneous velocity models are compared to show the importance of velocity model accuracy. Then, it was applied and verified by eight location premeasured blasting events. The synthetic results show that the spectrum characteristics of the recorded blasting waveforms are more complicated than those generated by the ideal Ricker wavelet, which provides a pragmatic way to evaluate the effectiveness and robustness of the MS event location method. The GBRTM location method does not need a highly accurate picking of phase arrival, just a simple detection criterion that the first arrival waveform can meet the windowing requirements of wavefield back propagation, which is beneficial for highly accurate and automatic MS event location. The GBRTM location accuracy using an appropriate 3D velocity model is much higher than that of using a homogeneous or 1D velocity model, emphasizing that a high-resolution velocity model is very critical to the GBRTM location method. The average location error of the GBRTM location method for the eight blasting events is just 17.0 m, which is better than that of the ray tracing method using the same 3D velocity model (26.2 m).
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Alejandra, Arecco. "Magnetogravimetric study on the Scotia Plate, in the South Atlantic Ocean for the characterization of tsunamis." Earthquake 2, no. 1 (2024): 1880. http://dx.doi.org/10.59429/ear.v2i1.1880.
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The marine and coastal environments of the Scotia Sea regions in the Southern Atlantic Ocean and Antarctica are vulnerable to the potentially disastrous effects of seismic activity along the Scotia Arc. This paper presents a magnetogravimetric study of the Scotia Plate for tsunami characterization. The influence of earthquakes on the Geomagnetic Field (GMF) is investigated using data from INTERMAGNET network observatories. A tectonic model is evaluated using gravity data from NOAA and seismic refraction data from Lamont-Doherty Earth Observatory. The study also assesses the impact on water level (WL) measured at Intergovernmental Oceanographic Commission (IOC) tide gauge stations. Cross Wavelet Transform (XWT) is applied, and a frequency analysis of the GMF is conducted to identify specific frequencies during seismic events. A 2D tectonic model is constructed for the North Scotia Ridge using gravimetric and seismic data to characterize structural boundaries that may be activated during seismic events. Water level records collected from 6 tide gauge stations in the region are filtered and analyzed to identify tsunamis at each station. The results reveal anomalous frequencies in the frequency analysis of the horizontal component of the GMF during the November 25, 2013 earthquake, with high data correlation from different observatories in the study area for periods of 0.5 and 1 hour. Gravimetric modeling delineates faults activated during seismic activity and edges of structures potentially activated due to the transcurrent and compressional nature of the margin. WL anomalies up to 1.30 m are obtained following earthquakes with a magnitude greater than 8. The propagation speed in the study area averaged 460 km/h, consistent with the expected speed for those depths, except for Puerto Argentino, which exceeded them in 50%.
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Dugstad, Johannes S., Pål Erik Isachsen, and Ilker Fer. "The mesoscale eddy field in the Lofoten Basin from high-resolution Lagrangian simulations." Ocean Science 17, no. 3 (2021): 651–74. http://dx.doi.org/10.5194/os-17-651-2021.
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Abstract. Warm Atlantic-origin waters are modified in the Lofoten Basin in the Nordic Seas on their way toward the Arctic. An energetic eddy field redistributes these waters in the basin. Retained for extended periods, the warm waters result in large surface heat losses to the atmosphere and have an impact on fisheries and regional climate. Here, we describe the eddy field in the Lofoten Basin by analyzing Lagrangian simulations forced by a high-resolution numerical model. We obtain trajectories of particles seeded at three levels – near the surface, at 200 m and at 500 m depth – using 2D and 3D velocity fields. About 200 000 particle trajectories are analyzed from each level and each simulation. Using multivariate wavelet ridge analysis, we identify coherent cyclonic and anticyclonic vortices in the trajectories and describe their characteristics. We then compare the evolution of water properties inside cyclones and anticyclones as well as in the ambient flow outside vortices. As measured from Lagrangian particles, anticyclones have longer lifetimes than cyclones (16–24 d compared to 13–19 d), a larger radius (20–22 km compared to 17–19 km) and a more circular shape (ellipse linearity of 0.45–0.50 compared to 0.51–0.57). The angular frequencies for cyclones and anticyclones have similar magnitudes (absolute values of about 0.05f). The anticyclones are characterized by warm temperature anomalies, whereas cyclones are colder than the background state. Along their path, water parcels in anticyclones cool at a rate of 0.02–0.04 ∘Cd-1, while those in cyclones warm at a rate of 0.01–0.02 ∘Cd-1. Water parcels experience a net downward motion in anticyclones and upward motion in cyclones, often found to be related to changes in temperature and density. The along-path changes in temperature, density and depth are smaller for particles in the ambient flow. An analysis of the net temperature and vorticity fluxes into the Lofoten Basin shows that while vortices contribute significantly to the heat and vorticity budgets, they only cover a small fraction of the domain area (about 6 %). The ambient flow, including filaments and other non-coherent variability undetected by the ridge analysis, hence plays a major role in closing the budgets of the basin.
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Carpenter, Chris. "Joint-Domain Full Waveform Inversion Avoids Cycle Skipping in Ultrashallow Water." Journal of Petroleum Technology 77, no. 02 (2025): 95–97. https://doi.org/10.2118/0225-0095-jpt.
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_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 219190, “Joint-Domain Full Waveform Inversion and Its Applications to Ultrashallow Water Oceanbottom-Node Data,” by Yang Yang, Han Yin, and Lian Duan, BGP, et al. The paper has not been peer reviewed. _ Full waveform inversion (FWI) is commonly used for high-resolution velocity model building. Conventional FWI with least-squares objective function often suffers from the problem of cycle skipping. This issue becomes prominent in subsurface structures with high complexity, significant deviations between the initial and true models, or a lack of low-frequency content in the data. To address the cycle-skipping problem, the authors present a novel joint-domain full waveform inversion (JDFWI) framework optimizing travel-time accuracy in both data and model domains. Introduction Various strategies have been proposed to address cycle skipping. One set of solutions involves using different objective functions to ameliorate the nonconvex nature inherent in the conventional least-squares objective function. This encompasses using time-lag-based objective functions or quadratic Wasserstein metric-based objective functions. Alternatively, for those adhering to the conventional least-squares objective function, another approach involves manipulating the data to circumvent cycle skipping. Additionally, low-frequency data can be extrapolated from its higher-frequency components through deep-learning techniques. A distinct category of methods, known as domain extension, introduces an additional degree of freedom in the model space to tackle cycle skipping. The inversion process is then reformulated to enforce the transition from a nonphysical model extension to a physical one. This extension can be incorporated either in the model space or in the data domain. The presented JDFWI framework optimizes travel-time accuracy in both data and model domains. In the model domain, the concept of delay time common image gathers (DTCIGs) is used to achieve precise travel-time measurements, while, in the data domain, the travel-time data misfit is extracted without the amplitude influence. Integrating a time-lag-based misfit function efficiently overcomes the cycle-skipping problem with the proposed JDFWI workflow. The authors include a subsection of the complete paper in which equations underpinning both conventional and joint-domain FWI are supplied and detailed. Synthetic Example The nonlinear state-space response, the curse of dimensionality, and the imperfect low-frequency content in both the model and data often increase the risk for conventional FWI to be trapped in the local minimum when using the objective function. As a simple demonstration, the authors first performed a 2D synthetic test to show the efficiency of the proposed JDFWI to overcome cycle skipping. The exact velocity model used in this synthetic test featured a chalk structure on the left and a large salt body on the right. Both high-velocity structures initiated as shallow as 2 km in depth. In the case of FWI, only when these structures were correctly inverted could the model below them reflect the exact geology. However, in the initial model for FWI, both high-velocity structures were missing and the difference to the exact velocity exceeded 2000 m/s in many places. The acquisition design for the inversion included 1,501 evenly spaced shots with 10-m spacing and 301 evenly spaced receivers with 50-m spacing across the whole model. Field data were simulated with a 1-Hz high-passed flat-spectrum wavelet.
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Umezu, Nobuyuki, Keisuke Yokota, and Masatomo Inui. "2D wavelet transform data compression with error level guarantee for Z-map models." Journal of Computational Design and Engineering 4, no. 3 (2017): 238–47. http://dx.doi.org/10.1016/j.jcde.2017.04.002.
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Abstract Most of workpiece shapes in NC milling simulations are in Z-map representations that require a very large amount of data to precisely hold a high resolution model. An irreversible compression algorithm for Z-map models using a two-dimensional Haar wavelet transform is proposed to resolve this tight memory situation for an ordinary PC. A shape model is first transformed by using Haar wavelet to build a wavelet synopsis tree while the maximum errors caused by virtually truncating high-frequency components are simultaneously calculated. The total amount of the shape data can be reduced by truncating particular sections of the wavelet components that satisfy the error threshold given by the user. Our algorithm guarantees that any error due to its irreversible compression processes is smaller than the specified level measured against the original model. A series of experiments were conducted using an Apple iMac with a 3.2 GHz CPU and 8 GB of memory. The experiments were performed with 16 sample shape models on 512×512 to 8192×8192 grids to evaluate the compression efficiency of the proposed method. Experimental results confirmed that our compression algorithm requires approximately 20–30 ms for 512×512 models and 7 s for 8192×8192 models under a maximum error level of 10× 10−6 m (a typical criteria for NC milling simulations). The compressed binaries outputted by the proposed method are generally 25–35% smaller than the baseline results by gzip, one of common reversible compression libraries, while these two methods require almost the same level of computational costs. Highlights Discarding diagonal components in WT significantly reduces data amount. The proposed method outperforms a reversible method by 25–35% in size reduction. Most of computational time is consumed by the reversible compression step. The proposed method compresses 5122 models in 20 ms, 81922 models in 7 s.
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Xing, Zhen, and Alfredo Mazzotti. "Two-grid full-waveform Rayleigh-wave inversion via a genetic algorithm — Part 2: Application to two actual data sets." GEOPHYSICS 84, no. 5 (2019): R815—R825. http://dx.doi.org/10.1190/geo2018-0800.1.
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We have applied our two-grid genetic-algorithm Rayleigh-wave full-waveform inversion (FWI) to two actual data sets acquired in Luni (Italy) and Grenoble (France), respectively. Because our technique used 2D elastic finite-difference modeling for solving the forward problem, the observed data were 3D to 2D corrected prior to the inversion. To limit the computing time, both inversions focused on predicting low-resolution, smooth models by using quite coarse inversion grids. The wavelets for FWI were estimated directly from the observed data by using the Wiener method. In the Luni case, due to the strong dispersion effects on the data, to strengthen the inversion, envelopes and waveforms were considered in the objective function and an offset-marching strategy was applied. Though no a priori information was exploited, the outcomes of the Luni and Grenoble data inversion were fair. The predicted Luni [Formula: see text] model indicates a strong velocity increase from approximately 3 to 6 m, and velocity inversions have been detected at approximately 2 and 9 m depths. Analyzing the dispersion spectra, it results that the predicted Luni data reasonably reproduced the waveforms related to the fundamental mode and, likely, a small part of those related to the first higher mode. Concerning the Grenoble example, the predicted [Formula: see text] model coincides reasonably well with the long-wavelength structures presented in the [Formula: see text] profiles obtained from nearby boreholes. The data reconstruction is generally satisfactory, and when mismatches occur between the predicted and observed traces, the phase differences are always within half-periods. The fair inversion outcomes suggest that the predicted Luni and Grenoble models would likely be adequate initial models for local FWI, which could further increase the resolution and the details of the estimated [Formula: see text] models.
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"Image Synthesis M/2D/HWT in VLSI Technology." International Journal of Innovative Technology and Exploring Engineering 9, no. 1 (2019): 2976–82. http://dx.doi.org/10.35940/ijitee.a9119.119119.
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Image synthesis is grouping of valid information from a group of images in to unique image. The ensuing image is an improved quality than any other images. The spectral deformation major con in standard method. The different multiscale transforms are proposed the overcome the issue. The image is affected by impulse noise because of satellite images, are filtered the impulse noise in the image syntehesis. In this paper we studied the architecture of Edge preserve algorithm which good in PSNR and MSE. The proposed technique using wavelet decomposition is implemented in Matlab for low resolution images are multispectral image and high resolution image are panchromatic image and then we combined the synthesized image in Altera Cyclone. The result shows the significant area and power. The synthesis image has a colour combination which is effective than any other in set of images.
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Juyoung, Kim, and Park Taegeun. "High Performance VLSI Architecture of 2D Discrete Wavelet Transform with Scalable Lattice Structure." International Journal of Electrical, Electronic and Communication Sciences 2.0, no. 6 (2009). https://doi.org/10.5281/zenodo.1334205.
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In this paper, we propose a fully-utilized, block-based 2D DWT (discrete wavelet transform) architecture, which consists of four 1D DWT filters with two-channel QMF lattice structure. The proposed architecture requires about 2MN-3N registers to save the intermediate results for higher level decomposition, where M and N stand for the filter length and the row width of the image respectively. Furthermore, the proposed 2D DWT processes in horizontal and vertical directions simultaneously without an idle period, so that it computes the DWT for an N×N image in a period of N2(1-2-2J)/3. Compared to the existing approaches, the proposed architecture shows 100% of hardware utilization and high throughput rates. To mitigate the long critical path delay due to the cascaded lattices, we can apply the pipeline technique with four stages, while retaining 100% of hardware utilization. The proposed architecture can be applied in real-time video signal processing.
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Xue, Gongbo, Hongyan Liu, Xiaoyi Cai, et al. "Impact of deep learning image reconstruction algorithms on CT radiomic features in patients with liver tumors." Frontiers in Oncology 13 (April 5, 2023). http://dx.doi.org/10.3389/fonc.2023.1167745.
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ObjectiveTo evaluate the impact of deep learning image reconstruction (DLIR) and adaptive statistical iterative reconstruction-Veo (ASIR-V) on abdominal CT radiomic features acquired in portal venous phase in liver tumor patients.MethodsSixty patients with liver tumors who underwent contrast-enhanced abdominal CT were retrospectively enrolled. Six groups including filtered back projection (FBP), ASIR-V (30%, 70%) and DLIR at low (DLIR-L), medium (DLIR-M and high (DLIR-H), were reconstructed using portal venous phase data. CT-based radiomic features (first-order, texture and wavelet features) were extracted from 2D and 3D liver tumors, peritumor and liver parenchyma. All features were analyzed for comparison. P &lt; 0.05 indicated statistically different. The consistency of 3D lesion feature extraction was assessed by calculating intraclass correlation coefficient (ICC).ResultsDifferent reconstruction algorithms influenced most radiomic features. The percentages of first-order, texture and wavelet features without statistical difference among 2D and 3D lesions, peritumor and liver parenchyma for all six groups were 27.78% (5/18), 5.33% (4/75) and 5.56% (1/18), respectively (all p &gt; 0.05), and they decreased while the level of reconstruction strengthened for both ASIR-V and DLIR. Compared with FBP, the features of ASIR-V30% and 70% without statistical difference decreased from 71.31% to 23.95%, and DLIR-L, DLIR-M, and DLIR-H decreased from 31.65% to 27.11% and 23.73%. Among texture features, unaffected features of peritumor were larger than those of lesions and liver parenchyma, and unaffected 3D lesions features were larger than those of 2D lesions. The consistency of 3D lesion first-order features was excellent, with intra- and inter-observer ICCs ranging from 0.891 to 0.999 and 0.880 to 0.998.ConclusionsBoth ASIR-V and DLIR algorithms with different strengths influenced the radiomic features of abdominal CT images in portal venous phase, and the influences aggravated as reconstruction strength increased.
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Langston, Charles A. "Phased Array Analysis Incorporating the Continuous Wavelet Transform." Bulletin of the Seismological Society of America, June 8, 2021. http://dx.doi.org/10.1785/0120210001.
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ABSTRACT Nonlinear block thresholding of the continuous wavelet transform (CWT) of 2D phased array signals offers high time-resolution solutions for analyzing seismograms of local and regional seismic events. An initial denoising step on an array ensemble reveals the regions of the scale-time plane that contain high signal-to-noise arrivals. Individual seismic phase arrivals in ensemble, denoised seismograms can be partitioned using scale-time gating in which CWT wave packets of an individual seismic phase on the scale-time plane for a reference array element are time-correlated with all other elements to find an optimum time shift for the phase across all elements. The seismic phase is then clipped out of the CWT of each array element using this optimal time shift for further analysis. The seismogram can be separated into component seismic waves for a detailed view of wave characteristics such as slowness and arrival azimuth using conventional frequency–wavenumber methods. However, the process can be taken further using the CWT of each phase to construct high time-resolution signal beams over the CWT scale. Local explosion data from the 2016 Incorporated Research Institutions for Seismology (IRIS) Wavefields Community Experiment in northern Oklahoma are used to demonstrate these techniques in separating surface-wave modes and body waves and to examine the scattering of regional phases. High-resolution CWT processing in the 1–3 Hz band for northern Oklahoma reveals horizontal Rayleigh-wave refraction and multipathing. Rayleigh-wave phase-velocity dispersion measurements are used to construct a 1D velocity model under the IRIS experiment. Scale-time gating helps expose near-source surface reflections from a local M 3.6 earthquake that are used to verify the 4 km source depth obtained from a published regional moment tensor solution.
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Silva de Lima, Newton, Julio Tota da Silva, Maurício José Alves Bolzam, Alan Dos Santos Ferreira, and Matheus Da Rocha Pietzsch. "A BRIEF OBSERVATION OF THE FORMATION OF COHERENT STRUCTURES AND TURBULENCE OVER A RAIN FOREST AREA IN CENTRAL AMAZÔNIA: THE ATTO-CLAIRE/IOP – 1/2012 EXPERIMENT." Revista Brasileira de Geofísica 35, no. 3 (2017). http://dx.doi.org/10.22564/rbgf.v35i3.882.
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ABSTRACT. This work used micrometeorological measurements of temperature and wind in order to characterize the turbulence due to wind in a terra firme forest in central Amazonia as part of the ATTO-CLAIRE / IOP-1 (2012) (Amazon Tall Tower Observatory – Cooperative LBA Airborne Regional Experiment / Intensive Observation Period – 2012 / LBA – Large Scale Biosphere-Atmosphere Experiment in the Amazon). This research was conducted at the Uatumã ATTO Sustainable Development Reserve in the State of Amazonas, Brazil, from February to September, 2012, and used data from February 26 to September 07, 2012, dates that partially encompass the wet and dry seasons, respectively. The ATTO site has 5 towers: one that is 320m, and four that are 80 m in height, and this research was conducted on an 80 m triangular tower. A total of ten 3D and 2D ultrasonic anemometers were installed on the tower, and the importance of these instruments used for flux measurements is also evident when taking into account the fact that the dissemination and diffusion of seeds and chemical composts in the forest happens through the action of turbulent fluxes. In order to understand the wind profile, the inflection point of the wind velocity, and coherent structures (ECs) and local turbulence, box-plot diagrams, quadrant analyses, wavelet potential spectrum, and energy potential analyses were conducted. The turbulence characterized at the ATTO had a roll or ramp structure during the study period, which represents favorable conditions for the maintenance of the forest during the wet and dry seasons in the Central Amazon. Keywords: inflection point, ramp, wavelet, turbulence. RESUMO. Este trabalho faz uso de medidas micrometeorológicas de temperatura e vento, com finalidade de caracterizar a turbulência aerotransportada em uma floresta de terra firme na Amazônia Central, realizadas no experimento ATTO-CLAIRE / IOP-1 (2012) (Amazon Tall Tower Observatory – Cooperative LBA Airborne Regional Experiment / Intensive Observation Period – 2012 / LBA – Large Scale Biosphere-Atmosphere Experiment in Amazônia), no sítio do ATTO, na Reserva de Desenvolvimento Sustentável do Uatumã – AM (Brasil) nos meses de fevereiro a setembro de 2012, com dados analisados a partir do dia 26 de fevereiro de 2012 até o dia 7 de setembro de 2012, entre as estações úmida e seca na Amazônia Central, no complexo de torres altas composta de 5 (cinco) torres; uma de 320 m e 4 (quatro) de 80 m. Este trabalho foi realizado na torre triangular (80 m). Foram instalados 10 (dez) anemômetros ultrassônicos de 3D e 2D. Equipamentos necessários em método de fluxos, visto que, a disseminação e difusão de sementes e compostos químicos da floresta, faz-se também por fluxos turbulentos. Para compreensão do perfil de vento, ponto de inflexão do perfil da velocidade do vento, estruturas coerentes e a turbulência local, para tal desenvolveu-se a partir dos dados processados, diagrama de caixa (box-plot ), análise de quadrantes, espectro de potência em ondeletas, espectro de energia. A turbulência caracterizada no ATTO, foi de estruturas do tipo “rolo” ou rampa, para o período estudado, condições favoráveis para manutenção da floresta em período úmido-seco na Amazônia Central.Palavras-chave: ponto de inflexão, rampa, ondeleta, turbulência.
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Vazifehkhah Hafteh, M., and A. Mahmoudian. "First Comprehensive Study of MSTID Generation and Propagation Characteristics in Iran." Journal of Geophysical Research: Space Physics 129, no. 12 (2024). https://doi.org/10.1029/2024ja033190.
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AbstractTo investigate medium‐scale TID (MSTIDs) at mid‐latitudes across Iran, TEC data obtained from a dense ground‐based GNSS receiver during the 7 months from May–November 2021 were analyzed. To remove the diurnal variability of the TEC, an 8th‐order Butterworth bandpass filter was applied to the data. Then, two‐dimensional TEC maps of the detrended TEC with a spatial resolution of 0.5 0.5 in longitude and latitude were obtained. Considering MSTID periods, four bandpass filters were applied to the TEC data: 10–15, 15–20, 20–25, and 25–30 min. The objective was to determine whether MSTID propagation occurred during specific times and whether consistent directions were followed. The results indicate that MSTIDs in all bandpass filters exhibit the same direction at particular times. Distinctive MSTID features are revealed by lower period filters. To identify MSTID trends propagating throughout the region within each month, stations along a constant longitude were selected. The trends of each month were depicted using the Continuous Wavelet Transform (CWT) technique applied to the detrended TEC. The resulting 2D map illustrates MSTID occurrence trends based on the combination of day of the month and time of day. No nighttime trend, except for two cases in July, is observed. Most of the observed MSTID trends propagate southeastward. Notably, as the end of each month approaches, there is a time shift to earlier hours for MSTID activity. The horizontal phase velocity, wavelength, and amplitude of the trends fall within the range of 200–615 m/s, 152–460 km, and dTECU, respectively.
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Plesniak, Michael W., and Kartik V. Bulusu. "Morphology of Secondary Flows in a Curved Pipe With Pulsatile Inflow." Journal of Fluids Engineering 138, no. 10 (2016). http://dx.doi.org/10.1115/1.4033962.
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A multiplicity of secondary flow morphologies is produced in the arterial network due to complexities in geometry (such as curvature, branching, and tortuosity) and pulsatility in the blood flow. In clinical literature, these morphologies have been called “spiral blood flow structures” and have been associated with a protective role toward arterial wall damage in the ascending and abdominal aorta. Persistent secondary flow (vortical) structures as observed experimentally in planar cross sections have been associated with flow instabilities. This study presents the results of two rigorous in vitro experimental investigations of secondary flow structures within a 180-deg bent tube model of curved arteries. First, phase-averaged, two-component, two-dimensional, particle image velocimetry (2C-2D PIV) experiments were performed at the George Washington University. Second, phase-locked, three-component, three-dimensional magnetic resonance velocimetry (3C-3D MRV) measurements were done at the Richard M. Lucas Center at Stanford University. Under physiological (pulsatile) inflow conditions, vortical patterns of a variety of scales, swirl magnitudes (strengths), and morphologies were found. A continuous wavelet transform (CWT) algorithm (pivlet 1.2) was developed for coherent structure detection and applied to out-of-plane vorticity (ω) fields. Qualitative comparisons of coherent secondary flow structures from the PIV and magnetic resonance velocimetry (MRV) data were made. In addition to the qualitative depiction of such planar vortical patterns, a regime map has also been presented. The phase dependence of the secondary flow structures under physiological flow conditions and the concomitant 3D nature of these vortical patterns required the full resolution of the flow field achieved by MRV techniques.
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Ellien, A., M. Montes, S. L. Ahad, et al. "Euclid: Early Release Observations. The intracluster light of Abell 2390." Astronomy & Astrophysics, May 6, 2025. https://doi.org/10.1051/0004-6361/202554460.
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Intracluster light (ICL) provides a record of the dynamical interactions undergone by clusters, giving clues on cluster formation and evolution. Here, we analyse the properties of ICL in the massive cluster Abell 2390 at redshift z=,0.228. Our analysis is based on the deep images obtained by the Euclid mission as part of the Early Release Observations in the near-infrared ( bands), using the NISP instrument in a 0.75,deg^2 field. We subtracted a point--spread function (PSF) model and removed the Galactic cirrus contribution in each band after modelling it with the DAWIS software. We then applied three methods to detect, characterise, and model the ICL and the brightest cluster galaxy (BCG): the CICLE 2D multi-galaxy fitting; the DAWIS wavelet-based multiscale software; and a mask-based 1D profile fitting. We detect ICL out to 600,kpc. The ICL fractions derived by our three methods range between 18,% and 36,% (average of 24,%), while the BCG+ICL fractions are between 21,% and 41,% (average of 29,%), depending on the band and method. A galaxy density map based on 219 selected cluster members shows a strong cluster substructure to the south-east and a smaller feature to the north-west. Ellipticals dominate the cluster's central region, with a centroid offset from the BCG by about 70,kpc and distribution following that of the ICL, while spirals do not trace the entire ICL but rather substructures. The comparison of the BCG+ICL, mass from gravitational lensing, and X-ray maps show that the BCG+ICL is the best tracer of substructures in the cluster. Based on colours, the ICL (out to about 400 kpc) seems to be built by the accretion of small systems (M ∼ solarmass ), or from stars coming from the outskirts of Milky Way-type galaxies (M ∼ 10^ solarmass ). Though Abell 2390 does not seem to be undergoing a merger, it is not yet fully relaxed, since it has accreted two groups that have not fully merged with the cluster core. We estimate that the contributions to the inner 300,kpc of the ICL of the north-west and south-east subgroups are 21,% and 9,% respectively.
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Bellil, Wajdi, Chokri Ben Amar, and Adel M. Alimi. "A SURVEY ON WAVELET NETWORK, MULTI LIBRARY WAVELET NETWORK TRAINING, 1D-2D FUNCTION APPROXIMATION AND A NEW IMAGE COMPRESSION METHOD." International Journal of Computing, August 1, 2014, 79–86. http://dx.doi.org/10.47839/ijc.8.1.659.
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This paper presents an original architecture of Wavelet Neural Network (WNN) based on multi Wavelets activation function and uses a selection method to determine a set of best wavelets whose centers and dilation parameters are used as initial values for subsequent training library WNN for color image compression and coding which consists to transform an RGB image into Luminance-Chrominance space and then segment the luminance in a set of m blocks n by n pixels. These blocks should be transferred row by row (1D input vector) to the input of our wavelet network. Every input vector will be considered as unknown functional mapping and then it will be approximated by the network.
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Houriez--Gombaud-Saintonge, Sophia, Elie Mousseaux, Ioannis Bargiotas, et al. "Comparison of different methods for the estimation of aortic pulse wave velocity from 4D flow cardiovascular magnetic resonance." Journal of Cardiovascular Magnetic Resonance 21, no. 1 (2019). http://dx.doi.org/10.1186/s12968-019-0584-x.
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Abstract Background Arterial pulse wave velocity (PWV) is associated with increased mortality in aging and disease. Several studies have shown the accuracy of applanation tonometry carotid-femoral PWV (Cf-PWV) and the relevance of evaluating central aorta stiffness using 2D cardiovascular magnetic resonance (CMR) to estimate PWV, and aortic distensibility-derived PWV through the theoretical Bramwell-Hill model (BH-PWV). Our aim was to compare various methods of aortic PWV (aoPWV) estimation from 4D flow CMR, in terms of associations with age, Cf-PWV, BH-PWV and left ventricular (LV) mass-to-volume ratio while evaluating inter-observer reproducibility and robustness to temporal resolution. Methods We studied 47 healthy subjects (49.5 ± 18 years) who underwent Cf-PWV and CMR including aortic 4D flow CMR as well as 2D cine SSFP for BH-PWV and LV mass-to-volume ratio estimation. The aorta was semi-automatically segmented from 4D flow data, and mean velocity waveforms were estimated in 25 planes perpendicular to the aortic centerline. 4D flow CMR aoPWV was calculated: using velocity curves at two locations, namely ascending aorta (AAo) and distal descending aorta (DAo) aorta (S1, 2D-like strategy), or using all velocity curves along the entire aortic centreline (3D-like strategies) with iterative transit time (TT) estimates (S2) or a plane fitting of velocity curves systolic upslope (S3). For S1 and S2, TT was calculated using three approaches: cross-correlation (TTc), wavelets (TTw) and Fourier transforms (TTf). Intra-class correlation coefficients (ICC) and Bland-Altman biases (BA) were used to evaluate inter-observer reproducibility and effect of lower temporal resolution. Results 4D flow CMR aoPWV estimates were significantly (p < 0.05) correlated to the CMR-independent Cf-PWV, BH-PWV, age and LV mass-to-volume ratio, with the strongest correlations for the 3D-like strategy using wavelets TT (S2-TTw) (R = 0.62, 0.65, 0.77 and 0.52, respectively, all p < 0.001). S2-TTw was also highly reproducible (ICC = 0.99, BA = 0.09 m/s) and robust to lower temporal resolution (ICC = 0.97, BA = 0.15 m/s). Conclusions Reproducible 4D flow CMR aoPWV estimates can be obtained using full 3D aortic coverage. Such 4D flow CMR stiffness measures were significantly associated with Cf-PWV, BH-PWV, age and LV mass-to-volume ratio, with a slight superiority of the 3D strategy using wavelets transit time (S2-TTw).
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Roncoroni, G., P. Koyan, E. Forte, J. Tronicke, and M. Pipan. "A realistic 2D multi-offset, multi-frequency synthetic GPR data set as a benchmark for testing new algorithms." Scientific Data 12, no. 1 (2025). https://doi.org/10.1038/s41597-024-04300-1.
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Abstract We present a 2D multi-offset, multi-frequency synthetic GPR data set specifically designed to evaluate and test processing, analysis and inversion techniques. The data set replicates realistic subsurface conditions at four sections separated by 2 m. We modeled four multi-offset GPR profiles at 50, 100 and 200 MHz frequencies using realistic wavelets. The data set provides a robust framework for validating advanced GPR algorithms and techniques such as pre-stack depth migration, amplitude versus offset analysis and full waveform inversion. Extensive technical validation ensures data reproducibility and affordability. The standardized, realistic synthetic data set can be used as a reliable benchmark for developing and testing new algorithms and methods, thereby advancing the understanding of subsurface imaging and real-world data interpretation.