Journal articles: 'II. Filtering'

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Ersoy, Okan K. "Nonlinear matched filtering II." Optical Engineering 29, no. 9 (1990): 1002. http://dx.doi.org/10.1117/12.55697.

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Banik, N. C., I. Lerche, J. R. Resnick, and R. T. Shuey. "Stratigraphic filtering, Part II: Model spectra." GEOPHYSICS 50, no. 12 (December 1985): 2775–83. http://dx.doi.org/10.1190/1.1441898.

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We describe filtering by short‐period multiples in one dimension using a combination of the O’Doherty‐Anstey (1971) formula with a stochastic model in which the autocorrelation of acoustic impedance decreases exponentially with lag [Formula: see text] while the spectrum of reflection coefficients rises with frequency up to a corner, then is approximately constant, [Formula: see text] An impedance log with these statistics is a generalization of the classic random telegraph wave. The parameter [Formula: see text], the mean‐square fractional fluctuation of impedance, is typically less than 1 percent, although we show an example where it is as high as 13 percent. The corner frequency [Formula: see text] is inversely related to average bed thickness. Typical values are 50–100 Hz, at the upper end of the normal seismic band. The cyclic stratification discussed by O’Doherty and Anstey (1971) and others corresponds to [Formula: see text] above the seismic band. Some logs have more reflection power at low frequencies than predicted from high frequencies by this model. We describe in both frequency and time domains the filtering of a seismic wavelet by multiples in such a stratigraphic sequence. The impulse response has a direct arrival, followed by a long tail of multiply scattered energy. The greater the impedance fluctuations or the longer the traveltime, the more amplitude is transferred from the primary to the multiples. We discuss in less detail several other models, including periodic and nearly periodic bedding. We also include two numerical applications of the O’Doherty‐Anstey formula; we show on a specific logged interval the formula’s remarkable accuracy for both attenuation and time delay; and we describe the reduction in computed time delay due to coarser sampling of the log.

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Li, Shaozhong, and Jacob B. Khurgin. "Carrier filtering in type II superlattices." Solid State Communications 85, no. 6 (February 1993): 535–38. http://dx.doi.org/10.1016/0038-1098(93)90014-e.

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Belavkin, V. P. "Measurement and Filtering of Quantum Diffusion II." Theory of Probability & Its Applications 39, no. 3 (January 1995): 363–78. http://dx.doi.org/10.1137/1139026.

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Hansen, C. "Digital image processing for clinicians, part II: Filtering." Journal of Nuclear Cardiology 9, no. 4 (July 2002): 429–37. http://dx.doi.org/10.1067/mnc.2002.122898.

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Nelson, Daniel B., and Dean P. Foster. "Filtering and forecasting with misspecified ARCH models II." Journal of Econometrics 67, no. 2 (June 1995): 303–35. http://dx.doi.org/10.1016/0304-4076(94)01635-d.

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Politsch, Collin A., Jessi Cisewski-Kehe, Rupert A. C. Croft, and Larry Wasserman. "Trend filtering – II. Denoising astronomical signals with varying degrees of smoothness." Monthly Notices of the Royal Astronomical Society 492, no. 3 (January 14, 2020): 4019–32. http://dx.doi.org/10.1093/mnras/staa110.

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ABSTRACT Trend filtering – first introduced into the astronomical literature in Paper I of this series – is a state-of-the-art statistical tool for denoising 1D signals that possess varying degrees of smoothness. In this work, we demonstrate the broad utility of trend filtering to observational astronomy by discussing how it can contribute to a variety of spectroscopic and time-domain studies. The observations we discuss are (1) the Lyman-α (Lyα) forest of quasar spectra; (2) more general spectroscopy of quasars, galaxies, and stars; (3) stellar light curves with planetary transits; (4) eclipsing binary light curves; and (5) supernova light curves. We study the Lyα forest in the greatest detail – using trend filtering to map the large-scale structure of the intergalactic medium along quasar-observer lines of sight. The remaining studies share broad themes of: (1) estimating observable parameters of light curves and spectra; and (2) constructing observational spectral/light-curve templates. We also briefly discuss the utility of trend filtering as a tool for 1D data reduction and compression.

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Perko, R., H. Raggam, K. H. Gutjahr, and M. Schardt. "ADVANCED DTM GENERATION FROM VERY HIGH RESOLUTION SATELLITE STEREO IMAGES." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-3/W4 (March 11, 2015): 165–72. http://dx.doi.org/10.5194/isprsannals-ii-3-w4-165-2015.

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This work proposes a simple filtering approach that can be applied to digital surface models in order to extract digital terrain models. The method focusses on robustness and computational efficiency and is in particular tailored to filter DSMs that are extracted from satellite stereo images. It represents an evolution of an existing DTM generation method and includes distinct advancement through the integration of multi-directional processing as well as slope dependent filtering, thus denoted “MSD filtering”. The DTM generation workflow is fully automatic and requires no user interaction. Exemplary results are presented for a DSM generated from a Pléiades tri-stereo image data set. Qualitative and quantitative evaluations with respect to highly accurate reference LiDAR data confirm the effectiveness of the proposed algorithm.

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Ruano-Ordás, David. "Model for optimising the execution of anti-spam filters." Inteligencia Artificial 19, no. 58 (December 18, 2016): 45. http://dx.doi.org/10.4114/intartif.vol19iss58pp45-48.

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During last years, the combination of several filtering techniques for the development of anti-spam systems has gained a enormous popularity. However, although the accuracy achieved by these models has increased considerably, its use has entailed the emergence of new challenges such as the need to reduce the excessive use of computational resources, the increase of filtering speed and the adjustment of the weights used for the combination of several filtering techniques. In order to achieve this goal we have been refined several aspects including: (i) the design and development of small technical improvements to increase the overall performance of the filter, (ii) application of genetic algorithms to increase filtering accuracy and (iii) the use of scheduling algorithms to improve filtering throughput.

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Lu, Yang, and Xiaoli Wang. "EFFECT OF METABOLIC ENZYMES ON ACCELERATION ABILITY IN EXERCISE FATIGUE." Revista Brasileira de Medicina do Esporte 27, no. 3 (September 2021): 257–61. http://dx.doi.org/10.1590/1517-8692202127032021_0128.

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ABSTRACT Introduction Study the relationship between the metabolic enzyme and the biological image, filtered by an adaptive filtering algorithm. Objective The research aims to In this study, human metabolic enzymes were evaluated by electrocardiogram and electromyogram images, and an adaptive filtering algorithm removed the noises in the images. Methods The electrocardiogram and electromyogram images at different periods were obtained, and the calculation method and application scope of the adaptive filtering algorithm were analysed. Results Adaptive filter was designed by the combination of adaptive filtering algorithm and dynamic information. Therefore, the artefact of the image was removed. Conclusions The adaptive filtering algorithm can effectively remove the noise or artefact in electrocardiogram and electromyogram signals. The optimal image information can be obtained. Level of evidence II; Therapeutic studies - investigation of treatment results.

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DOI, Shigeki, Haruo TAKAHASHI, Eiji SHIMIZU, and Minoru MATSUDA. "Scale-space filtering on the underwater information transmission part II." Journal of the Marine Acoustics Society of Japan 17, no. 4 (1990): 238–45. http://dx.doi.org/10.3135/jmasj.17.238.

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Kleinert, M., and U. Stilla. "INFORMATION FILTERING WITH SUBMAPS FOR INERTIAL AIDED VISUAL ODOMETRY." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-3/W4 (March 11, 2015): 87–94. http://dx.doi.org/10.5194/isprsannals-ii-3-w4-87-2015.

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This work is concerned with the fusion of inertial measurements (accelerations and angular velocities) with imagery data (feature points extracted in a video stream) in a recursive bundle adjustment framework for indoor position and attitude estimation. Recursive processing is achieved by a combination of local submaps and the Schur complement. The Schur complement is used to reduce the problem size at regular intervals while retaining the information provided by past measurements. Local submaps provide a way to propagate the gauge constraints and thereby to alleviate the detrimental effects of linearization errors in the prior. Though the presented technique is not real-time capable in its current implementation, it can be employed to process arbitrarily long trajectories. The presented system is evaluated by comparing the estimated trajectory of the system with a reference trajectory of a prism attached to the system, which was recorded by a total station.

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Kabius, B., V. Seybold, S. Hiller, A. Rilk, E. Zellmann, and W. Probst. "Energy-Filtering Techniques for Thick Samples." Microscopy and Microanalysis 6, S2 (August 2000): 166–67. http://dx.doi.org/10.1017/s1431927600033328.

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Imaging of sample regions with a thickness significantly larger than the extinction length and strong thickness variations introduces two major problems for transmission electron microscopy (TEM) : (i) inelastic scattering increases the energy width of the transmitted electrons and therefore the resolution decreases (ii) the contrast differences caused by thickness variations can be higher than the dynamic range of the detector system.Both problems can be solved by using energy filtering techniques. The advantage here is that for energy filtered imaging the resolution limit is not determined by the sample thickness but by the width of the energy selection aperture. Fig. 1 shows three envelope functions of the temporal coherence calculated for different values of the energy width. The functions were plotted for an acceleration voltage of 200 kV and a high voltage stability of 2 ppm.

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Pérez Hernández, F., and J. Christensen-Dalsgaard. "The phase function for stellar acoustic oscillations – II. Effects of filtering." Monthly Notices of the Royal Astronomical Society 267, no. 1 (March 1994): 111–24. http://dx.doi.org/10.1093/mnras/267.1.111.

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Braun, Nils, and Thomas Kuhr. "Software for online reconstruction and filtering at the Belle II experiment." International Journal of Modern Physics A 35, no. 33 (November 30, 2020): 2043001. http://dx.doi.org/10.1142/s0217751x20430010.

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The Belle II experiment is designed to collect 50 times more data than its predecessor. For a smooth collection of high-quality data, a robust and automated data transport and processing pipeline has been established. We describe the basic software components employed by the high level trigger. It performs a reconstruction of all events using the same algorithms as offline, classifies the events according to physics criteria, and provides monitoring information. The improved system described in this paper has been deployed successfully since 2019.

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Urteaga, Inigo, and Petar M. Djuric. "Sequential Estimation of Hidden ARMA Processes by Particle Filtering—Part II." IEEE Transactions on Signal Processing 65, no. 2 (January 15, 2017): 494–504. http://dx.doi.org/10.1109/tsp.2016.2598324.

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Yau, Shing-Tung, and Stephen S. T. Yau. "Real Time Solution of the Nonlinear Filtering Problem without Memory II." SIAM Journal on Control and Optimization 47, no. 1 (January 2008): 163–95. http://dx.doi.org/10.1137/050648353.

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Hubbert, J. C., M. Dixon, and S. M. Ellis. "Weather Radar Ground Clutter. Part II: Real-Time Identification and Filtering." Journal of Atmospheric and Oceanic Technology 26, no. 7 (July 1, 2009): 1181–97. http://dx.doi.org/10.1175/2009jtecha1160.1.

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Abstract The identification and mitigation of anomalous propagation (AP) and normal propagation (NP) ground clutter is an ongoing problem in radar meteorology. Scatter from ground-clutter targets routinely contaminates radar data and masks weather returns causing poor data quality. The problem is typically mitigated by applying a clutter filter to all radar data, but this also biases weather data at near-zero velocity. Modern radar processors make possible the real-time identification and filtering of AP clutter. A fuzzy logic algorithm is used to distinguish between clutter echoes and precipitation echoes and, subsequently, a clutter filter is applied to those radar resolution volumes where clutter is present. In this way, zero-velocity weather echoes are preserved while clutter echoes are mitigated. Since the radar moments are recalculated from clutter-filtered echoes, the underlying weather echo signatures are revealed, thereby significantly increasing the visibility of weather echo. This paper describes the fuzzy logic algorithm, clutter mitigation decision (CMD), for clutter echo identification. A new feature field, clutter phase alignment (CPA), is introduced and described. A detailed discussion of CPA is given in Part I of this paper. The CMD algorithm is illustrated with experimental data from the Denver Next Generation Weather Radar (NEXRAD) at the Denver, Colorado, Front Range Airport (KFTG); and NCAR’s S-band dual-polarization Doppler radar (S-Pol).

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Leroux, C., H. Jones, A. Clenet, B. Dreux, M. Becu, and B. Tisseyre. "Simulating yield datasets: an opportunity to improve data filtering algorithms." Advances in Animal Biosciences 8, no. 2 (June 1, 2017): 600–605. http://dx.doi.org/10.1017/s2040470017000899.

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Yield maps are a powerful tool with regard to managing upcoming crop productions but can contain a large amount of defective data that might result in misleading decisions. The objective of this work is to help improve and compare yield data filtering algorithms by generating simulated datasets as if they had been acquired directly in the field. Two stages were implemented during the simulation process (i) the creation of spatially correlated datasets and (ii) the addition of known yield sources of errors to these datasets. A previously published yield filtering algorithm was applied on these simulated datasets to demonstrate the applicability of the methodology. These simulated datasets allow results of yield data filtering methods to be compared and improved.

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Lee, Byong-Ju, Deg-Hyo Bae, and Eylon Shamir. "Stochastic Continuous Storage Function Model with Ensemble Kalman Filtering (II) : Application and Verification." Journal of Korea Water Resources Association 42, no. 11 (November 30, 2009): 963–72. http://dx.doi.org/10.3741/jkwra.2009.42.11.963.

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Toma, Cristian. "Filtering Method Based on Symmetrical Second Order Systems." Symmetry 11, no. 6 (June 20, 2019): 813. http://dx.doi.org/10.3390/sym11060813.

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This study presents a filtering and sampling structure based on symmetrical second order systems working on half-period. It is shown that undamped second order oscillating systems working on half-period could provide: (i) a large attenuation coefficient for an alternating signal (due to the filtering second order system), and (ii) a robust sampling procedure (the slope of the generated output being zero at the sampling time moment). Unlike previous studies on the same topics, these results are achieved without the use of an additional integrator.

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Yanushevskaya, E. I., V. I. Suprunchuk, and E. V. Ivanyuk. "Impact of polyhexamethylene guanidine on filtering of Pb(II) and Cd(II) hydroxides from aqueous solutions." Journal of Water Chemistry and Technology 38, no. 5 (September 2016): 273–79. http://dx.doi.org/10.3103/s1063455x16050052.

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Zheng, Zhen, Bingting Zha, Yu Zhou, Jinbo Huang, Youshi Xuchen, and He Zhang. "Single-Stage Adaptive Multi-Scale Point Cloud Noise Filtering Algorithm Based on Feature Information." Remote Sensing 14, no. 2 (January 13, 2022): 367. http://dx.doi.org/10.3390/rs14020367.

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This paper proposes a single-stage adaptive multi-scale noise filtering algorithm for point clouds, based on feature information, which aims to mitigate the fact that the current laser point cloud noise filtering algorithm has difficulty quickly completing the single-stage adaptive filtering of multi-scale noise. The feature information from each point of the point cloud is obtained based on the efficient k-dimensional (k-d) tree data structure and amended normal vector estimation methods, and the adaptive threshold is used to divide the point cloud into large-scale noise, a feature-rich region, and a flat region to reduce the computational time. The large-scale noise is removed directly, the feature-rich and flat regions are filtered via improved bilateral filtering algorithm and weighted average filtering algorithm based on grey relational analysis, respectively. Simulation results show that the proposed algorithm performs better than the state-of-art comparison algorithms. It was, thus, verified that the algorithm proposed in this paper can quickly and adaptively (i) filter out large-scale noise, (ii) smooth small-scale noise, and (iii) effectively maintain the geometric features of the point cloud. The developed algorithm provides research thought for filtering pre-processing methods applicable in 3D measurements, remote sensing, and target recognition based on point clouds.

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Smirnova, Ekaterina, Snehalata Huzurbazar, and Farhad Jafari. "PERFect: PERmutation Filtering test for microbiome data." Biostatistics 20, no. 4 (June 18, 2018): 615–31. http://dx.doi.org/10.1093/biostatistics/kxy020.

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Summary The human microbiota composition is associated with a number of diseases including obesity, inflammatory bowel disease, and bacterial vaginosis. Thus, microbiome research has the potential to reshape clinical and therapeutic approaches. However, raw microbiome count data require careful pre-processing steps that take into account both the sparsity of counts and the large number of taxa that are being measured. Filtering is defined as removing taxa that are present in a small number of samples and have small counts in the samples where they are observed. Despite progress in the number and quality of filtering approaches, there is no consensus on filtering standards and quality assessment. This can adversely affect downstream analyses and reproducibility of results across platforms and software. We introduce PERFect, a novel permutation filtering approach designed to address two unsolved problems in microbiome data processing: (i) define and quantify loss due to filtering by implementing thresholds and (ii) introduce and evaluate a permutation test for filtering loss to provide a measure of excessive filtering. Methods are assessed on three “mock experiment” data sets, where the true taxa compositions are known, and are applied to two publicly available real microbiome data sets. The method correctly removes contaminant taxa in “mock” data sets, quantifies and visualizes the corresponding filtering loss, providing a uniform data-driven filtering criteria for real microbiome data sets. In real data analyses PERFect tends to remove more taxa than existing approaches; this likely happens because the method is based on an explicit loss function, uses statistically principled testing, and takes into account correlation between taxa. The PERFect software is freely available at https://github.com/katiasmirn/PERFect.

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Maltezos, E., and C. Ioannidis. "AUTOMATIC DETECTION OF BUILDING POINTS FROM LIDAR AND DENSE IMAGE MATCHING POINT CLOUDS." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-3/W5 (August 19, 2015): 33–40. http://dx.doi.org/10.5194/isprsannals-ii-3-w5-33-2015.

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This study aims to detect automatically building points: (a) from LIDAR point cloud using simple techniques of filtering that enhance the geometric properties of each point, and (b) from a point cloud which is extracted applying dense image matching at high resolution colour-infrared (CIR) digital aerial imagery using the stereo method semi-global matching (SGM). At first step, the removal of the vegetation is carried out. At the LIDAR point cloud, two different methods are implemented and evaluated using initially the normals and the roughness values afterwards: (1) the proposed scan line smooth filtering and a thresholding process, and (2) a bilateral filtering and a thresholding process. For the case of the CIR point cloud, a variation of the normalized differential vegetation index (NDVI) is computed for the same purpose. Afterwards, the bare-earth is extracted using a morphological operator and removed from the rest scene so as to maintain the buildings points. The results of the extracted buildings applying each approach at an urban area in northern Greece are evaluated using an existing orthoimage as reference; also, the results are compared with the corresponding classified buildings extracted from two commercial software. Finally, in order to verify the utility and functionality of the extracted buildings points that achieved the best accuracy, the 3D models in terms of Level of Detail 1 (LoD 1) and a 3D building change detection process are indicatively performed on a sub-region of the overall scene.

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Samsudin, Nooraisyah N., Dr Suhaila Isaak, and Dr Norlina Paraman. "Implementation of Optimized Low Pass Filter for ECG filtering using Verilog." Journal of Physics: Conference Series 2312, no. 1 (August 1, 2022): 012049. http://dx.doi.org/10.1088/1742-6596/2312/1/012049.

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Abstract Electrocardiogram is a standard method used for the diagnosis of heart related disease. QRS complex plays an important role in Electrocardiogram signal processing since it is the prominent feature of Electrocardiogram signal. One of the important modules in the QRS detection algorithm is filtering. Electrocardiogram signal is processed to filter out unwanted signal through digital filtering. The main objective of this paper is to compare the resource utilization of hardware realization consumed between Direct Form I structure and Direct Form II structure. In this work, Infinite Impulse Response low pass filter to remove high frequency noise is designed with a passband frequency and stopband frequency of 5 and 25 Hz respectively. The designed filter is verified using Matlab Filter Design Analysis tool and realized in hardware using Verilog. Both the results show that the unwanted signals in the raw ECG signal are attenuated through the designed filter. The resource utilization result shows improvement with optimized Direct Form II implementation. The amount of look up tables, flip flop and digital signal processing used with Direct Form II structure shows a reduction to 0.26%, 0.12% and 2.50% respectively compared to 1.17%, 0.20%, 2.92% of utilization with Direct Form I structure.

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Burratti, Luca, Marco Zannotti, Valentin Maranges, Rita Giovannetti, Leonardo Duranti, Fabio De De Matteis, Roberto Francini, and Paolo Prosposito. "Poly(Ethylene Glycol) Diacrylate Hydrogel with Silver Nanoclusters for Water Pb(II) Ions Filtering." Gels 9, no. 2 (February 4, 2023): 133. http://dx.doi.org/10.3390/gels9020133.

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Poly(ethylene glycol) diacrylate (PEGDA) hydrogels modified with luminescent silver nanoclusters (AgNCs) are synthesized by a photo-crosslinking process. The hybrid material thus obtained is employed to filter Pb(II) polluted water. Under the best conditions, the nanocomposite is able to remove up to 80–90% of lead contaminant, depending on the filter composition. The experimental results indicate that the adsorption process of Pb(II) onto the modified filter can be well modeled using the Freundlich isotherm, thus revealing that the chemisorption is the driving process of Pb(II) adsorption. In addition, the parameter n in the Freundlich model suggests that the adsorption process of Pb(II) ions in the modified hydrogel is favored. Based on the obtained remarkable contaminant uptake capacity and the overall low cost, this hybrid system appears to be a promising sorbent material for the removal of Pb(II) ions from aqueous media.

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Hu, Grace X., David R. Kuipers, and Yong Zeng. "Bayesian Inference via Filtering Equations for Ultrahigh Frequency Data (II): Model Selection." SIAM/ASA Journal on Uncertainty Quantification 6, no. 1 (January 2018): 61–86. http://dx.doi.org/10.1137/16m1094774.

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Chu, Dongsheng, Meng Liang, Xin Shi, and Ling Zhang. "Optimal filtering algorithm for stochastic 2-D FMM II with multiplicative noise." Journal of Ocean University of China 3, no. 1 (April 2004): 106–10. http://dx.doi.org/10.1007/s11802-004-0018-7.

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GHOSH, N., R. S. WADHWA, B. S. SHROTRI, and D. PATELLA. "LOW-PASS FILTERING OF NOISY FIELD SCHLUMBERGER SOUNDING CURVES PART II: APPLICATION*." Geophysical Prospecting 34, no. 1 (February 1986): 124–29. http://dx.doi.org/10.1111/j.1365-2478.1986.tb00457.x.

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Majda, George. "Filtering Techniques for Systems of Stiff Ordinary Differential Equations II. Error estimates." SIAM Journal on Numerical Analysis 22, no. 6 (December 1985): 1116–34. http://dx.doi.org/10.1137/0722067.

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Hespel, Laurent, André Delfour, and Bernard Guillame. "Mie light-scattering granulometer with an adaptive numerical filtering method II Experiments." Applied Optics 40, no. 6 (February 20, 2001): 974. http://dx.doi.org/10.1364/ao.40.000974.

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Brédif, M. "Projective Texturing Uncertain Geometry: silhouette-aware box-filtered blending using integral radial images." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-3 (August 7, 2014): 17–23. http://dx.doi.org/10.5194/isprsannals-ii-3-17-2014.

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Projective texturing is a commonly used image based rendering technique that enables the synthesis of novel views from the blended reprojection of nearby views on a coarse geometry proxy approximating the scene. When scene geometry is inexact, aliasing artefacts occur. This introduces disturbing artefacts in applications such as street-level immersive navigation in mobile mapping imagery, since a pixel-accurate modelling of the scene geometry and all its details is most of the time out of question. The filtered blending approach applies the necessary 1D low-pass filtering on the projective texture to trade out the aliasing artefacts at the cost of some radial blurring. This paper proposes extensions of the filtered blending approach. Firstly, we introduce Integral Radial Images that enable constant time radial box filtering and show how they can be used to apply box-filtered blending in constant time independently of the amount of depth uncertainty. Secondly, we show a very efficient application of filtered blending where the scene geometry is only given by a loose depth interval prior rather than an actual geometry proxy. Thirdly, we propose a silhouette-aware extension of the box-filtered blending that not only account for uncertain depth along the viewing ray but also for uncertain silhouettes that have to be blurred as well.

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Ménétrier, Benjamin, Thibaut Montmerle, Yann Michel, and Loïk Berre. "Linear Filtering of Sample Covariances for Ensemble-Based Data Assimilation. Part II: Application to a Convective-Scale NWP Model." Monthly Weather Review 143, no. 5 (May 1, 2015): 1644–64. http://dx.doi.org/10.1175/mwr-d-14-00156.1.

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Abstract In Part I of this two-part study, a new theory for optimal linear filtering of covariances sampled from an ensemble of forecasts was detailed. This method, especially designed for data assimilation (DA) schemes in numerical weather prediction (NWP) systems, has the advantage of using optimality criteria that involve sample estimated quantities and filter output only. In this second part, the theory is tested with real background error covariances computed using a large ensemble data assimilation (EDA) at the convective scale coupled with a large EDA at the global scale, based respectively on the Applications of Research to Operations at Mesoscale (AROME) and ARPEGE operational NWP systems. Background error variances estimated with a subset of this ensemble are filtered and evaluated against values obtained with the remaining members, which are considered as an independent reference. Algorithms presented in Part I show relevant results, with the homogeneous filtering being quasi optimal. Heterogeneous filtering is also successfully tested with different local criteria, yet at a higher computational cost, showing the full generality of the method. As a second application, horizontal and vertical localization functions are diagnosed from the ensemble, providing pertinent localization length scales that consistently depend on the number of members, on the meteorological variables, and on the vertical levels.

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Cepec, Jaka, and Peter Grajzl. "Measuring the effectiveness of bankruptcy institutions: filtering failures in Slovenian financial reorganizations." Journal of Institutional Economics 15, no. 3 (March 27, 2019): 553–67. http://dx.doi.org/10.1017/s1744137418000437.

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AbstractWe examine the effectiveness of bankruptcy institutions at promoting socially efficient allocation of resources. Under the Slovenian simplified reorganization procedure, firms with rejected reorganization proposals are not automatically liquidated. This unique institutional feature facilitates an estimation of the extent of different types of filtering failures. Based on an ex-post conceptualization of firm viability, Type I errors (the acceptance of plans by non-viable firms) are more likely than Type II errors (the rejection of plans by viable firms) and the overall incidence of filtering failure is 27%. Based on an ex-ante conceptualization of firm viability, any given reduction in Type II errors would give rise to three times as many Type I errors. We contextualize our findings in the light of prior results in the literature, alternative mechanisms for insolvency resolution, and related bankruptcy reorganization schemes internationally where courts are awarded a comparatively more prominent role.

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Kolokoltsov, Vassili. "CTRW modeling of quantum measurement and fractional equations of quantum stochastic filtering and control." Fractional Calculus and Applied Analysis 25, no. 1 (February 2022): 128–65. http://dx.doi.org/10.1007/s13540-021-00002-2.

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AbstractInitially developed in the framework of quantum stochastic calculus, the main equations of quantum stochastic filtering were later on derived as the limits of Markov models of discrete measurements under appropriate scaling. In many branches of modern physics it became popular to extend random walk modeling to the continuous time random walk (CTRW) modeling, where the time between discrete events is taken to be non-exponential. In the present paper we apply the CTRW modeling to the continuous quantum measurements yielding the new fractional in time evolution equations of quantum filtering and thus new fractional equations of quantum mechanics of open systems. The related quantum control problems and games turn out to be described by the fractional Hamilton-Jacobi-Bellman (HJB) equations on Riemannian manifolds. By-passing we provide a full derivation of the standard quantum filtering equations, in a modified way as compared with existing texts, which (i) provides explicit rates of convergence (that are not available via the tightness of martingales approach developed previously) and (ii) allows for the direct applications of the basic results of CTRWs to deduce the final fractional filtering equations.

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Kemao, Qian, and Seah Hock Soon. "A Simple Phase Unwrapping Approach Based on Filtering by Windowed Fourier Transform (II)." Key Engineering Materials 326-328 (December 2006): 67–70. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.67.

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Phase unwrapping is an important and challenging process in optical interferometry. Difficulties in phase unwrapping are usually caused by either noise (“bad” pixels) or invalid areas (“bad” regions). If the “bad” pixels can be removed, the problems due to the noise are solved. Further, if the “bad” regions can be identified, they can be avoided in phase unwrapping. In our previous work the noise can be successfully removed using a windowed Fourier transform [Optics and Lasers Technology, 37:458-462 (2005)]. In this paper we will show that the invalid areas can be identified by the same windowed Fourier transform. Thus a single windowed Fourier transform is able to process both “bad” pixels and “bad” regions simultaneously, which makes the phase unwrapping simple and effective.

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Sacher, William, and Peter Bartello. "Sampling Errors in Ensemble Kalman Filtering. Part II: Application to a Barotropic Model." Monthly Weather Review 137, no. 5 (May 1, 2009): 1640–54. http://dx.doi.org/10.1175/2008mwr2685.1.

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Abstract In the current study, the authors are concerned with the comparison of the average performance of stochastic versions of the ensemble Kalman filter with and without covariance inflation, as well as the double ensemble Kalman filter. The theoretical results obtained in Part I of this study are confronted with idealized simulations performed with a perfect barotropic quasigeostrophic model. Results obtained are very consistent with the analytic expressions found in Part I. It is also shown that both the double ensemble Kalman filter and covariance inflation techniques can avoid filter divergence. Nevertheless, covariance inflation gives efficient results in terms of accuracy and reliability for a much lower computational cost than the double ensemble Kalman filter and for smaller ensemble sizes.

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Prasad, S., and S. D. Joshi. "A new recursive pseudo least squares algorithm for ARMA filtering and modeling. II." IEEE Transactions on Signal Processing 40, no. 11 (1992): 2775–83. http://dx.doi.org/10.1109/78.165664.

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Sadeghi, Roksana, Arathy Kartha, Michael P. Barry, Paul Gibson, Avi Caspi, Arup Roy, and Gislin Dagnelie. "Thermal and Distance image filtering improve independent mobility in Argus II retinal implant." Journal of Vision 19, no. 15 (December 1, 2019): 23. http://dx.doi.org/10.1167/19.15.23.

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Parhi, K. K., and D. G. Messerschmitt. "Pipeline interleaving and parallelism in recursive digital filters. II. Pipelined incremental block filtering." IEEE Transactions on Acoustics, Speech, and Signal Processing 37, no. 7 (July 1989): 1118–34. http://dx.doi.org/10.1109/29.32287.

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Kannan, D. "Discrete–time nonlinear filtering with marked point process observations: ii. risk–sensitive filters." Stochastic Analysis and Applications 18, no. 2 (January 2000): 261–87. http://dx.doi.org/10.1080/07362990008809667.

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Kim, Saemi, Hyeong Jin Chun, Kyung Won Lee, and Hyun C. Yoon. "Smartphone-integrated urinary CTX-II immunosensor based on wavelength filtering from chromogenic reaction." Biosensors and Bioelectronics 150 (February 2020): 111932. http://dx.doi.org/10.1016/j.bios.2019.111932.

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Loizou, Christos P., and Constantinos S. Pattichis. "Despeckle Filtering for Ultrasound Imaging and Video, Volume II: Selected Applications, Second Edition." Synthesis Lectures on Algorithms and Software in Engineering 7, no. 2 (August 12, 2015): 1–180. http://dx.doi.org/10.2200/s00663ed1v01y201508ase015.

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Schäfer, B. M., C. Pfrommer, R. M. Hell, and M. Bartelmann. "Detecting Sunyaev-Zel'dovich clusters with Planck- II. Foreground components and optimized filtering schemes." Monthly Notices of the Royal Astronomical Society 370, no. 4 (July 6, 2006): 1713–36. http://dx.doi.org/10.1111/j.1365-2966.2006.10622.x.

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Hill, S. G., S. D. Snyder, B. S. Cazzolato, N. Tanaka, and R. Fukuda. "A generalized approach to modal filtering for active noise control. II. Acoustic sensing." IEEE Sensors Journal 2, no. 6 (December 2002): 590–96. http://dx.doi.org/10.1109/jsen.2002.807775.

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Kumar, Mohit, Norbert Stoll, Regina Stoll, and Kerstin Thurow. "A Stochastic Framework for Robust Fuzzy Filtering and Analysis of Signals—Part II." IEEE Transactions on Cybernetics 45, no. 3 (March 2015): 472–82. http://dx.doi.org/10.1109/tcyb.2014.2329192.

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McJannet, David, Jim Wallace, Rex Keen, Aaron Hawdon, and Joseph Kemei. "The filtering capacity of a tropical riverine wetland: II. Sediment and nutrient balances." Hydrological Processes 26, no. 1 (April 26, 2011): 53–72. http://dx.doi.org/10.1002/hyp.8111.

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DOUGHERTY, EDWARD R., and ROBERT P. LOCE. "ROBUST MORPHOLOGICALLY CONTINUOUS FOURIER DESCRIPTORS II: CONTINUITY AND OCCLUSION ANALYSIS." International Journal of Pattern Recognition and Artificial Intelligence 06, no. 05 (December 1992): 893–911. http://dx.doi.org/10.1142/s021800149200045x.

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Fourier descriptors based upon the waveform induced by a pattern's projection overcome a number of classic difficulties with Fourier-descriptor methodology. Not only are the descriptors invariant with respect to scale, translation, and rotation (as is usually the case), they are also continuous in the Hausdorff metric and robust with respect to both point noise and occlusion; insensitivity with respect to minimum occlusions is perhaps their most significant advantage. Continuity in the Hausdorff metric allows prediction of the effect on the descriptors when morphologically filtering a pattern. The effect of occlusion is also predictable.

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Kermedchieva, Ralitsa D., Marieta Konareva-Kostianeva, Vesela Mitkova-Hristova, Marin Atanasov, and Nina S. Stoyanova. "Confocal Microscopy of Filtering Blebs after Trabeculectomy." Folia Medica 63, no. 6 (December 31, 2021): 905–12. http://dx.doi.org/10.3897/folmed.63.e58949.

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Introduction: Filtration surgery is the most effective method of lowering intraocular pressure (IOP) in patients with insufficient medical control. It consists in facilitating the drainage of the intraocular fluid (IOF) from the anterior chamber to the subconjunctival space and subsequent lowering of IOP. The formation of filtration blebs (FB) and the processes of scarring occurring in the conjunctiva are of particular importance in glaucoma surgery. In many cases, the appearance of FB does not match the IOP values, and what causes the failure after trabeculectomy often remains unclear. Often, over time, there is a change in the structure of the FB, as fibrous tissue grows, which prevents the IOF drainage. Laser scanning in vivo confocal microscopy is a non-invasive study allowing the production of layered images at the microstructural level with high resolution of both the cornea and other structures of the anterior ocular surface. Aim: To evaluate the morphological structure and function of filtering blebs after trabeculectomy using in vivo confocal microscopy taking into account the type of implant and when the surgery was performed. Materials and methods: The study included 33 patients, 46 eyes with glaucoma. Twenty-six of the eyes had primary open-angle glaucoma (POAG), 18 eyes had pseudoexfoliative glaucoma and 2 eyes had juvenile glaucoma. All patients underwent trabeculectomy with fornix-based flap, and three of the eyes underwent retrabeculectomy. Mitomicyn C (MMC) was administered intraoperatively to all patients. The study of the filtering bleb was performed by in vivo confocal microscopy (CFM) (Heidelberg Retina Tomograph II (HRT II) /Rostock Cornea Module/ (Heidelberg Engineering GmbH, Heidelberg, Germany), the period from trabeculectomy and examination being from 1 year to 22 years. An Express implant was placed in 14 eyes, Ologen implant in 7 eyes, and 25 eyes had no implant placed. In the analysis of the morphological structure of the filtering blebs, three indicators were evaluated: the type of epithelium, the type of stroma, and blood vessels. Results: Statistical significance was established with regard to the function and morphological structure of the filtering bleb (p=0.009). Blebs with fine collagen mesh and dense collagen mesh demonstrate good function. In the case of blebs with insufficient function, those with a dense collagen network and hyper-reflective tissue predominated and there were no blebs with a fine collagen network, and in non-functioning blebs most common were those with a pronounced collagen network and hyper-reflective tissue. With regard to vascularization, we found that the functioning blebs in the shortest postoperative period were dominated by those with one blood vessel (stage 1) and there was no stage 3, with weak tortuosity, while in non-functioning blebs in the late postoperative period, there was moderate to severe vascularization and tortuosity (p=0.037), (p=0.043), (p=0.047), (p=0.021). The type of implant affects the tortuosity of the blood vessels of the filtering bleb (p=0.026). The blebs with Express implants show a slight tortuosity, followed by the blebs with Ologen implants. The highest percentage of highly kinked blood vessels occurred in blebs without an implant. Conclusions: In vivo confocal microscopy is an innovative method which allows visualization of the internal structure of the filtering blebs at a cellular level, giving us a new insight into the ongoing healing processes, premising the function of the filtering blebs after glaucoma surgery.

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Journal articles on the topic 'II. Filtering'

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