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1
Trantham, E. Clark. "Minimum uncertainty filters for pulses." GEOPHYSICS 58, no. 6 (1993): 853–62. http://dx.doi.org/10.1190/1.1443469.
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The objective of this paper is to calculate filters with a minimum uncertainty, the product of filter length and bandwidth. The method is applicable to producing minimum uncertainty filters with time or frequency domain constraints on the filter. The calculus of variations is used to derive the conditions that minimize a filter’s uncertainty. The general solution is a linear combination of Hermite functions, where the Hermite functions are summed from low to high order until the filter’s constraints are met. Filters constrained to have zero amplitude at zero hertz have an uncertainty at least three times greater than expected from the uncertainty principle, and the minimum uncertainty filter is a first derivative Gaussian. For the previous filter, the minimum uncertainty high cut filter is a Gaussian function of frequency, but the minimum uncertainty low cut filter is a linear function of frequency.
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Ahmed, Osman, Shermeen Sheikh, Patrick Tran, et al. "Inferior Vena Cava Filter Evaluation and Management for the Diagnostic Radiologist: A Comprehensive Review Including Inferior Vena Cava Filter-Related Complications and PRESERVE Trial Filters." Canadian Association of Radiologists Journal 70, no. 4 (2019): 367–82. http://dx.doi.org/10.1016/j.carj.2019.06.003.
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Inferior vena cava filters are commonly encountered devices on diagnostic imaging that were highlighted in a 2010 Food and Drug Administration safety advisory regarding their complications from long-term implantation. The Predicting the Safety and Effectiveness of Inferior Vena Cava Filters (PRESERVE) trial is an ongoing after-market study investigating the safety and utility of commonly utilized filters in practice today. While most of these filters are safe, prompt recognition and management of any filter-associated complication is imperative to prevent or reduce the morbidity and mortality associated with them. This review is aimed at discussing the appropriate utilization and placement of inferior vena cava filters in addition to the recognition of filter-associated complications on cross-sectional imaging. An overview of the PRESRVE trial filters is also provided to understand each filter's propensity for specific complications.
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Li, Luping, Lijuan Dong, Peng Chen, and Kai Yang. "Multi-band rejection filters based on spoof surface plasmon polaritons and folded split-ring resonators." International Journal of Microwave and Wireless Technologies 11, no. 08 (2019): 774–81. http://dx.doi.org/10.1017/s1759078719000369.
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AbstractA dualband rejection filter and a triband rejection filter are proposed in this letter, both of which are implemented by cascading spoof surface plasmon polaritons (SSPPs) of the same structure but with diverse rejection bands. Compared with traditional ones, the proposed filters provide more compact structures, wider rejection bands, and better independent tunability. In the proposed filters, the rejection bandwidth, the center frequency of the rejection band and the filter's cutoff frequency can be adjusted independently. And the different rejection bands in the same filter also can be independently controlled. Agreements between the dispersion of SSPP units and the S21 of filters are also presented. Measurement results demonstrate that both filters load multiple rejection bands on the 27.7 GHz wide low-pass band and all the rejection bands locate in Ku and K bands. The average rejection bandwidth and the average rejection depth of the two filters are 1.49 GHz and 42.1 dB, respectively.
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Wang, Wenli, and Philip Winters. "Statistically Significant Efficiency Testing of HEPA Filters." Journal of the IEST 47, no. 1 (2004): 101–6. http://dx.doi.org/10.17764/jiet.47.1.bq380t6134311822.
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High Efficiency Particulate Air (HEPA) filter manufacturers must ensure the accuracy of efficiency testing for these filters and, at the same time, keep productivity at a reasonable level. This study describes tests conducted to determine the minimum time required to provide statistically significant efficiencies of HEPA filters using a test system currently in use of HEPA filter production. The test results of over 300 HEPA filters were analyzed in this study. The approaches in IEST RP-CC-007.1: Testing ULPA Filters for statistical analysis of particle counts were followed. A Poisson distribution was used to describe the variations and to calculate the lower and upper limits of measured counts at 95% confidence level. This study shows that 90 seconds is sufficient for this test system to determine whether a HEPA filter has an efficiency of 99.990% or higher at 95% confidence. Longer tests will cause the mean measured efficiency to approach the filter's true efficiency and also narrow the confidence interval. However, challenging HEPA filters made of glass fiber media with oil aerosols for up to one hour does not significantly change the filter's true efficiency performance. The preferred approach for a new test system is to use software that calculates the confidence limits of filter efficiency after each sampling cycle and determines whether to continue testing. For an existing system without this type of program (such as the one evaluated in this study), analysis is necessary to make sure the HEPA filters are challenged with enough aerosol particles.
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Hruschka, Crassen, Udo Barabas, and Lutz Gohler. "Optical narrow band filter without resonance's." Facta universitatis - series: Electronics and Energetics 17, no. 2 (2004): 209–17. http://dx.doi.org/10.2298/fuee0402209h.
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This paper introduces an optical wave filter, which uses gratings at 45? or 135? inclined grating lines that avoid any resonance's. Therefore, many more options to form the filter shape exist. In general, the filter design can be traced to that of transversal filters (finite impulse response filter, FIR filter). Such an integrated optical wave filter is characterized by steep filter slopes and a narrow pass band (less then 01nm) combined with a high stop band attenuation (more than 40dB) and a linear phase response in the pass band. Compared to conventional Bragg grating filters, the inclined grating line filters can have a flatter pass band and steeper filter skirts related to the width of the pass band. In general, the filter's realization is possible using any optical material. In view of the excellent optical properties the semiconductor material system InP/InGaAsP is used for manufacturing the filter.
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Wang, Shuaijie, Haitao Wang, Xuefeng Qiu, et al. "Study on the Performance of Filters Under Biogas Slurry Drip Irrigation Systems." Agriculture 15, no. 1 (2024): 30. https://doi.org/10.3390/agriculture15010030.
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Filters are essential components for maintaining the stability of drip irrigation systems, effectively reducing the risk of clogging. However, when applied to slurry drip irrigation systems, the complexity of slurry water quality makes it unclear how different filter types and their combinations affect the hydraulic performance of the system. This study provides a comprehensive performance evaluation of two common filter types and their combinations, considering various flow rates and biogas slurry-to-water ratios under drip irrigation conditions. The results revealed the following key findings: (1) In the application of biogas slurry drip irrigation, an increase in the concentration or flow rate of the slurry significantly affects the hydraulic performance of the filter, increasing the risk of clogging and shortening the operational lifespan. Notably, the impact of changes in slurry concentration on the hydraulic performance of the filter is much greater than that of the flow rate. Compared to mesh filters, disk filters offer better hydraulic performance, with the contaminant capacity of disk filters being approximately three times that of mesh filters. (2) In biogas slurry drip irrigation, the filter combination generally outperforms single filters in terms of hydraulic performance and contaminant removal capacity. Due to the unique nature of the water source in biogas slurry, a selection process for filter combinations was conducted. It was found that when a disk filter is used as the pre-filter and a mesh filter as the post-filter, the overall rate of head loss change is the smallest, and the clogging uniformity is the least. (3) In the entropy weight-TOPSIS comprehensive evaluation, the filter’s operating time and contaminant capacity are key factors affecting its overall performance. From the perspective of improving the operational stability of the biogas slurry drip irrigation system, it is recommended to use a disk filter + mesh filter combination. This study conducts practical measurements on the hydraulic performance, contaminant removal capacity, filtration accuracy, and other indicators of commonly used mesh and disk filters, aiming to provide useful references for the practical application of biogas slurry drip irrigation filters.
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Wen, Richard, Hunter McCoy, David Tench, et al. "Adaptive Quotient Filters." Proceedings of the ACM on Management of Data 2, no. 4 (2024): 1–28. http://dx.doi.org/10.1145/3677128.
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Filters trade off accuracy for space and occasionally return false positive matches with a bounded error. Numerous systems use filters in fast memory to avoid performing expensive I/Os to slow storage. A fundamental limitation in traditional filters is that they do not change their representation upon seeing a false positive match. Therefore, the maximum false positive rate is only guaranteed for a single query, not for an arbitrary set of queries. We can improve the filter's performance on a stream of queries, especially on a skewed distribution, if we can adapt after encountering false positives. Adaptive filters, such as telescoping quotient filters and adaptive cuckoo filters, update their representation upon detecting a false positive to avoid repeating the same error in the future. Adaptive filters require an auxiliary structure, typically much larger than the main filter and often residing on slow storage, to facilitate adaptation. However, existing adaptive filters are not practical and have not been adopted in real-world systems for two main reasons. First, they offer weak adaptivity guarantees, meaning that fixing a new false positive can cause a previously fixed false positive to come back. Secondly, the sub-optimal design of the auxiliary structure results in adaptivity overheads so substantial that they can actually diminish overall system performance compared to a traditional filter. In this paper, we design and implement the \sysname, the first practical adaptive filter with minimal adaptivity overhead and strong adaptivity guarantees, which means that the performance and false-positive guarantees continue to hold even for adversarial workloads. The \sysname is based on the state-of-the-art quotient filter design and preserves all the critical features of the quotient filter such as cache efficiency and mergeability. Furthermore, we employ a new auxiliary structure design which results in considerably low adaptivity overhead and makes the \sysname practical in real systems. We evaluate the \sysname by using it to filter queries to an on-disk B-tree database and find no negative impact on insert or query performance compared to traditional filters. Against adversarial workloads, the \sysname preserves system performance, whereas traditional filters incur 2× slowdown from adversaries representing as low as 1% of the workload. Finally, we show that on skewed query workloads, the \sysname can reduce the false-positive rate 100× using negligible (1/1000th of a bit per item) space overhead.
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Kang, Wei, Li Xia Zhang, and Ji Bo Wan. "Matching Characteristic of Constant Voltage Source Excited Filter in Power System." Applied Mechanics and Materials 427-429 (September 2013): 1072–75. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.1072.
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Filters between voltage source converter and the batteries in power system can be categorized into constant voltage source excited filters. The paper discusses the importance of the matched structure and parameters for power filters. The relation between matched structure and filters output characteristic is demonstrated and the design principle is introduced. The work above proved that even if the filters are designed for the same transfer function, so long as filters load resistance is different, their designed parameters are also different. Traditional power system filter seldom consider its both ends load matching characteristic. When the difference between filter's load characteristic and practical system equivalent impedance are large, the actual filtering effect becomes worse, current loss arises and even there may be the possibility of resonance. As the lack of energy resource and energy crisis is gradually becoming a serious problem, energy conservation is important. Constant voltage source excited circuit configuration model is established through the simulation and test. The results show the validity and feasibility of the method that filter should be designed the according to its load characteristic in practical application.
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Prasad, K. D., and R. Ramadevi. "Analysis and Comparison of Image Enhancement Techniques for Improving PSNR of Liver Images by Median Filtering over Mask Filtering." CARDIOMETRY, no. 25 (February 14, 2023): 990–95. http://dx.doi.org/10.18137/cardiometry.2022.25.990-995.
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Aim: The goal of this research is to employ median filters and mask filters to reduce noise in liver images so that they can be improved. In addition, the Peak Signal to Noise Ratio of both filters’ outputs was examined (PSNR). Materials and Methods: The afflicted and normal liver photos were obtained from the Kaggle website for this investigation. Then, using Matlab software, the mask filtering and median filtering algorithms were run. Clinicalc. com was used to compute sample size, and SPSS software was used to conduct the comparative analysis. This study has two groups, each with a sample size of 20 people with an average G power of 80%. The innovative median filter’s performance is assessed, and the PSNR performance metric is compared to that of the mask filter. Results: The PSNR of innovative median filters is 64.0310, while mask filters have a PSNR of 78.0095, according to Matlab simulation data. The significant value of PSNR (Peak Signal to Noise Ratio) (0.409) and p>0.05 was found in the statistical analysis. Conclusion: The innovative median filter delivers greater PSNR than the mask filter for medical image enhancement on ultrasound liver pictures, according to this study.
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Khandelwal, Achala, and Pragya Nema. "Application of PI controller based active filter for harmonic mitigation of grid-connected PV-system." Bulletin of Electrical Engineering and Informatics 10, no. 5 (2021): 2377–83. http://dx.doi.org/10.11591/eei.v10i5.2907.
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The recent trends show the interconnection of PV system with electric grid. With this configuration the issue of harmonics comes into existence. The mounting figure of power-electronic instruments has formed considerable impression on the power-quality of electric supply. Harmonics deformations have conventionally been handled amid the application of passive-LC filters. Active Filter has emerged as a good substitute for passive filters to reduce the harmonics to great extent as it has numerous benefits over the former filters. The active filter’s most vital part is the applied control strategies. Several researches are being under process to advance the functioning of the filter. One of the important control requirements of filter is the regulation of DC link up capacitor voltage. Here the voltage supervision of capacitor is being done using PI controller. The paper show current harmonics compensation of PV grid connected system using PI controller based active filter. Simulation outcomes have been shown which displays the harmonics are within the IEEE boundaries.
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Lu, Feng, Yihuan Huang, Jinquan Huang, and Xiaojie Qiu. "Gas turbine performance monitoring based on extended information fusion filter." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 2 (2018): 483–97. http://dx.doi.org/10.1177/0954410018776398.
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Performance monitoring is a critical issue for gas turbine engine for improving the operation safety and reducing the maintenance cost. With regard to this, variants of Kalman-filters-based state estimation have been employed to detect gas turbine performance, but the classical centralized Kalman filters are subject to heavy computational effort and poor fault tolerance. A novel nonlinear fusion filter algorithm using information description with distributed architecture is proposed and applied to gas turbine performance monitoring. This methodology is developed from federated Kalman filter, and a bank of local extended information filters and one information mixer are combined with extended information fusion filter. The local state estimates and covariance calculated in parallel by the local extended information filters are integrated in the information mixer to yield a global state estimate. The global state estimate of nonlinear system is fed back to the local filters with weighted factor for next iteration. The aim of the proposed methodology is to reduce the computational efforts of state estimation and improve robustness to sensor faults in cases of gas turbine performance monitoring. The simulation results on a turbofan engine confirm the extended information fusion filter's effective capabilities in comparison to the general central ones.
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Mewada, Hiren K., and Jitendra Chaudhari. "Low computation digital down converter using polyphase IIR filter." Circuit World 45, no. 3 (2019): 169–78. http://dx.doi.org/10.1108/cw-02-2019-0015.
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Purpose The digital down converter (DDC) is a principal component in modern communication systems. The DDC process traditionally entails quadrature down conversion, bandwidth reducing filters and commensurate sample rate reduction. To avoid group delay, distortion linear phase FIR filters are used in the DDC. The filter performance specifications related to deep stopband attenuation, small in-band ripple and narrow transition bandwidth lead to filters with a large number of coefficients. To reduce the computational workload of the filtering process, filtering is often performed as a two-stage process, the first stage being a down sampling Hoegenauer (or cascade-integrated comb) filter and a reduced sample rate FIR filter. An alternative option is an M-Path polyphase partition of a band cantered FIR filter. Even though IIR filters offer reduced workload to implement a specific filtering task, the authors avoid using them because of their poor group delay characteristics. This paper aims to propose the design of M-path, approximately linear phase IIR filters as an alternative option to the M-path FIR filter. Design/methodology/approach Two filter designs are presented in the paper. The first approach uses linear phase IIR low pass structure to reduce the filter’s coefficient. Whereas the second approach uses multipath polyphase structure to design approximately linear phase IIR filter in DDC. Findings The authors have compared the performance and workload of the proposed polyphase structured IIR filters with state-of-the-art filter design used in DDC. The proposed design is seen to satisfy tight design specification with a significant reduction in arithmetic operations and required power consumption. Originality/value The proposed design is an alternate solution to the M-path polyphase FIR filter offering very less number of coefficients in the filter design. Proposed DDC using polyphase structured IIR filter satisfies the requirement of linear phase with the least number of computation cost in comparison with other DDC structure.
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Ross, Hunter, Huyen Nguyen, Brian Nguyen, et al. "Filter Modified with Hydrophilic and Oleophobic Coating for Efficient and Affordable Oil/Water Separation." Separations 9, no. 10 (2022): 269. http://dx.doi.org/10.3390/separations9100269.
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To mitigate the damage of oil spills, a filter modified with a hydrophilic and oleophobic coating is proposed for affordable and efficient oil separation and recovery from water. The sol–gel method was chosen to produce a colloidal suspension of titanium dioxide particles for its ease of production and its versatility in application for many different substrates, including paper and cloth fabric. After immersing the substrates into a titanium-containing solution, three techniques were applied to increase the production of titanium dioxide—microwave-assisted, refrigeration, and ultra-sonication. Contact angle tests were done to investigate the change in the filter’s oleophobicity. The titanium dioxide present on the surface of the filter was amorphous, but all treatment methods showed an improvement in oleophobicity. All treated filters improved oil filtration performance by up to eighty percent. The filters isolated motor oil from a mixture while allowing water to pass through. The coated filters also displayed photocatalytic activity by degrading methylene blue on its surface when exposed to sunlight, demonstrating the filter’s self-cleaning ability. For real-world applications, the filter can be supported by a stainless mesh for enhanced strength and durability. While being dragged through the water, the filter collects the surface oil, allowing water to pass through via gravity.
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Chen, Zhimin, and Lenan Wu. "Design of Special Impacting Filter for Multicarrier ABPSK System." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/921932.
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A rather intuitive technique known as pole-zero placement is introduced to illustrate the frequency response of the special impacting filters (SIFs) with a pair of conjugate zero-poles and deduce the equation of the pole radii. Based on that, the paper proposes an iterative scheme to derive the parameters of the cascade notch filter. The cost function is determined by the cascading notch filter’s influence on impacting filters, converting the cost function’s least square problem to a filter parameters’ standard quadratic programming problem. Finally, a cascading notch SIF (CNSIF) designed to demodulate the ABPSK signals is realized.
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HAAVISTO, P., M. GABBOUJ, and Y. NEUVO. "MEDIAN BASED IDEMPOTENT FILTERS." Journal of Circuits, Systems and Computers 01, no. 02 (1991): 125–48. http://dx.doi.org/10.1142/s0218126691000021.
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Idempotent filters produce a root signal in a single filter pass, i.e. the filter output is invariant to further filterings with the same filter. In this paper median based idempotent filter structures are introduced. Two approaches to generate these filters are studied: weighted median filters and median filter cascades. Two subclasses of n-dimensional idempotent weighted median filters, called Class 1 and Class 2 filters in the paper, are introduced. It is shown that both Class 1 and Class 2 filters suppress impulsive noise from n-dimensional input signals and yet have almost no effect on the non-corrupted parts of the signal. These filters are therefore well-suited for example for preprocessing purposes. An application to speech processing is described. Other likely applications of these filters are in image processing and, also, in image sequence processing, where the filter mask is typically 3-dimensional. Sufficient conditions for a filter cascade to be idempotent are given. Two idempotent median filter cascades and their advantages are discussed.
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Deeds, Kyle, Brian Hentschel, and Stratos Idreos. "Stacked filters." Proceedings of the VLDB Endowment 14, no. 4 (2020): 600–612. http://dx.doi.org/10.14778/3436905.3436919.
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We present Stacked Filters, a new probabilistic filter which is fast and robust similar to query-agnostic filters (such as Bloom and Cuckoo filters), and at the same time brings low false positive rates and sizes similar to classifier-based filters (such as Learned Filters). The core idea is that Stacked Filters incorporate workload knowledge about frequently queried non-existing values. Instead of learning, they structurally incorporate that knowledge using hashing and several sequenced filter layers, indexing both data and frequent negatives. Stacked Filters can also gather workload knowledge on-the-fly and adaptively build the filter. We show experimentally that for a given memory budget, Stacked Filters achieve end-to-end query throughput up to 130x better than the best alternative for a workload, either query-agnostic or classifier-based filters, and depending on where data is (SSD or HDD).
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Koigerov, A. S. "Analytical Approach to Designing a Combined-Mode Resonator Filter on Surface Acoustic Waves Using the Model of Coupling of Modes." Journal of the Russian Universities. Radioelectronics 25, no. 2 (2022): 16–28. http://dx.doi.org/10.32603/1993-8985-2022-25-2-16-28.
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Introduction. Bandpass filters are important components that determine the basic characteristics of transmitting and receiving radio electronic equipment. Such filters implemented on surface acoustic waves (SAW) not only demonstrate excellent electrical parameters, but also meet compactness requirements. The relevant research task of reducing the design time and optimizing the filter’s cost can be solved by either using modern computational software or improving existing modeling tools.Aim. To describe the current state and main features of approaches to calculating SAW-based bandpass filters using the model of coupled modes and its formalization based on P-matrices. To describe the main principles and approaches on the example of designing a combined-mode resonator filter on leaky SAW and comparing the calculated and experimental data.Materials and methods. A theoretical study was carried out using the mathematical theory of differential equations presented in a matrix form, as well as the methods of finite element analysis and circuit theory. The results were processed in MatLab and COMSOL.Results. The current state of the analytical approach to designing SAW-based filters using the model of coupled modes and its formalization based on P-matrices was described. An original design for a resonator filter based on leaky SAW at 49° YX-cut of lithium niobate was proposed. The filter has a relative bandwidth of 5.8 %, an insertion loss of –3.7 dB, and a stop-band rejection of –50 dB. A technique for calculating SAW-based filters was proposed.Conclusion. The proposed analytical approach to designing SAW-based bandpass filters allows the filter characteristics (e.g., transmission factor) to be reliably predicted at the modeling stage, thereby reducing the number of experimental iterations and increasing the development efficiency.
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Koigerov, A. S. "Analytical Approach to Designing a Combined-Mode Resonator Filter on Surface Acoustic Waves Using the Model of Coupling of Modes." Journal of the Russian Universities. Radioelectronics 25, no. 2 (2022): 16–28. http://dx.doi.org/10.32603/1993-8985-2022-25-2-16-28.
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Introduction. Bandpass filters are important components that determine the basic characteristics of transmitting and receiving radio electronic equipment. Such filters implemented on surface acoustic waves (SAW) not only demonstrate excellent electrical parameters, but also meet compactness requirements. The relevant research task of reducing the design time and optimizing the filter’s cost can be solved by either using modern computational software or improving existing modeling tools.Aim. To describe the current state and main features of approaches to calculating SAW-based bandpass filters using the model of coupled modes and its formalization based on P-matrices. To describe the main principles and approaches on the example of designing a combined-mode resonator filter on leaky SAW and comparing the calculated and experimental data.Materials and methods. A theoretical study was carried out using the mathematical theory of differential equations presented in a matrix form, as well as the methods of finite element analysis and circuit theory. The results were processed in MatLab and COMSOL.Results. The current state of the analytical approach to designing SAW-based filters using the model of coupled modes and its formalization based on P-matrices was described. An original design for a resonator filter based on leaky SAW at 49° YX-cut of lithium niobate was proposed. The filter has a relative bandwidth of 5.8 %, an insertion loss of –3.7 dB, and a stop-band rejection of –50 dB. A technique for calculating SAW-based filters was proposed.Conclusion. The proposed analytical approach to designing SAW-based bandpass filters allows the filter characteristics (e.g., transmission factor) to be reliably predicted at the modeling stage, thereby reducing the number of experimental iterations and increasing the development efficiency.
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Ahmed, Mohammed Moyed. "Adaptive Digital Notch Filter for Enhanced Stability in Grid-Connected Inverter Systems." Acta Universitatis Sapientiae, Electrical and Mechanical Engineering 16 (January 8, 2025): 110–23. https://doi.org/10.47745/auseme-2024-0010.
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Grid-connected inverters with LCL filters are crucial components in renewable energy systems, but they face stability challenges due to varying grid impedances and resonant frequencies. This paper presents a novel adaptive digital notch filter designed to enhance the stability of such systems across a wide range of operating conditions. The proposed filter employs a three-step adaptive mechanism: resonance detection, determination of resonant frequency change direction, and dynamic notch frequency adjustment. A comprehensive stability analysis in the z-plane reveals the behavior of the resonant pole under different scenarios, informing the filter's design. The adaptive filter's performance was evaluated through simulations. Results demonstrate significant improvements in system stability compared to conventional fixed-frequency notch filters. In scenarios where the resonant frequency was lower than the initial notch frequency, the adaptive filter prevented current divergence and reduced the line current harmonic magnitude at the resonant frequency by up to 75%. In scenarios where the resonant frequency was higher than the notch frequency, the proposed filter successfully suppressed current oscillations, maintaining stability where conventional filters failed. The adaptive mechanism responded to instability within 2 ms, adjusting the notch frequency to optimal levels within 10 ms. This research contributes to the advancement of grid-connected power electronics, offering a robust solution that can enhance the reliability and efficiency of renewable energy integration by up to 30% under varying grid conditions.
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Gülünay, Necati. "Noncausal spatial prediction filtering for random noise reduction on 3-D poststack data." GEOPHYSICS 65, no. 5 (2000): 1641–53. http://dx.doi.org/10.1190/1.1444852.
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A common practice in random noise reduction for 2-D data is to use pseudononcausal (PNC) 1-D prediction filters at each temporal frequency. A 1-D PNC filter is a filter that is forced to be two sided by placing a conjugate‐reversed version of a 1-D causal filter in front of itself with a zero between the two. For 3-D data, a similar practice is to solve for two 2-D (causal) one‐quadrant filters at each frequency slice. A 2-D PNC filter is formed by putting a conjugate flipped version of each quadrant filter in a quadrant opposite itself. The center sample of a 2-D PNC filter is zero. This paper suggests the use of 1-D and 2-D noncausal (NC) prediction filters instead of PNC filters for random noise attenuation, where an NC filter is a two‐sided filter solved from one set of normal equations. The number of negative and positive lags in the NC filter is the same. The center sample of the filter is zero. The NC prediction filters are more center loaded than PNC filters. They are conjugate symmetric as PNC filters. Also, NC filters are less sensitive than PNC filters to the size of the gate used in their derivation. They can handle amplitude variations along dip directions better than PNC filters. While a PNC prediction filter suppresses more random noise, it damages more signal. On the other hand, NC prediction filters preserve more of the signal and reject less noise for the same total filter length. For high S/N ratio data, a 2-D NC prediction filter preserves geologic features that do not vary in one of the spatial dimensions. In‐line and cross‐line vertical faults are also well preserved with such filters. When faults are obliquely oriented, the filter coefficients adapt to the fault. Spectral properties of PNC and NC filters are very similar.
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Shaikh, Saba S., Suneel D. Kamath, Debashis Ghosh, Robert J. Lewandowski, and Brandon J. McMahon. "Safety and Outcomes of Permanent and Retrievable Inferior Vena Cava Filters in the Oncology Population." International Journal of Vascular Medicine 2020 (February 5, 2020): 1–7. http://dx.doi.org/10.1155/2020/6582742.
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Background. The role for inferior vena cava (IVC) filters in the oncology population is poorly defined. Objectives. Our primary endpoint was to determine the rate of filter placement in cancer patients without an absolute contraindication to anticoagulation and the rate of recurrent VTE after filter placement in both retrievable and permanent filter groups. Patients/Methods. A single-institution, retrospective study of patients with active malignancies and acute VTE who received a retrievable or permanent IVC filter between 2009-2013. Demographics and outcomes were confirmed on independent chart review. Cost data were obtained using Current Procedural Terminology (CPT) codes. Results. 179 patients with retrievable filters and 207 patients with permanent filters were included. Contraindication to anticoagulation was the most cited reason for filter placement; however, only 76% of patients with retrievable filters and 69% of patients with permanent filters had an absolute contraindication to anticoagulation. 20% of patients with retrievable filters and 24% of patients with permanent filters had recurrent VTE. The median time from filter placement to death was 8.9 and 3.2 months in the retrievable and permanent filter groups, respectively. The total cost of retrievable filters and permanent filters was $2,883,389 and $3,722,688, respectively. Conclusions. The role for IVC filters in cancer patients remains unclear as recurrent VTE is common and time from filter placement to death is short. Filter placement is costly and has a clinically significant complication rate, especially for retrievable filters. More data from prospective, randomized trials are needed to determine the utility of IVC filters in cancer patients.
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Piciu, Dana, Christina Theresia Dan, and Anca Dina. "Gődel filters in residuated lattices." Analele Universitatii "Ovidius" Constanta - Seria Matematica 29, no. 1 (2021): 183–200. http://dx.doi.org/10.2478/auom-2021-0012.
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Abstract In this paper, in the spirit of [4], we study a new type of filters in residuated lattices : Gődel filters. So, we characterize the filters for which the quotient algebra that is constructed via these filters is a Gődel algebra and we establish the connections between these filters and other types of filters. Using Gődel filters we characterize the residuated lattices which are Gődel algebras. Also, we prove that a residuated lattice is a Gődel algebra (divisible residuated lattice, MTL algebra, BL algebra) if and only if every filter is a Gődel filter (divisible filter, MTL filter, BL filter). Finally, we present some results about injective Gődel algebras showing that complete Boolean algebras are injective objects in the category of Gődel algebras.
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Lee, Min-Jeong, Hyeon-Ju Kim, Du-Hong Kang, Jung Woo Lee, and Jung-Yeul Yun. "Microstructure and Pore Characteristics of a Double-Layered Pore Structure Powder Filter Fabricated by the WPS Process." Metals 14, no. 6 (2024): 665. http://dx.doi.org/10.3390/met14060665.
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In order to supply high-purity process gas in the semiconductor manufacturing process, a gas filter is used to remove particles that may be contained in the gas. However, because the gas filters currently in use have simple pore structures, there is a need to increase filtration efficiency through the development of filters with complex pore structures. In this study, a metal powder filter with double-layered pores was manufactured using a Wet Powder Spraying process (WPS) to increase the filtering efficiency of gas filters used in semiconductor manufacturing. The effects of the mixing ratio of spherical-shape and flake-shape powders and the rolling process on the filter’s characteristics were investigated. The filter’s performance, microstructure, and surface roughness were evaluated by measuring porosity and gas permeability. The results showed that as the ratio of flake-shaped powder decreased, the thickness of the coating layer and the porosity of the filter decreased. Additionally, it was observed that as the rolling process progressed, the non-uniform pore structure was oriented parallel to the cross-section of the filter regardless of the mixing ratio. Measurements found that the gas permeability of the uncoated filter support was the highest, and that gas permeability decreased as the proportion of spherical powder increased regardless of the average particle size of the mixed powder. Lower gas permeability was observed in rolled samples. A filtration efficiency of LRV 3 or higher was confirmed.
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Yassin, Ali, Hocine Cherifi, Hamida Seba, and Olivier Togni. "Backbone extraction through statistical edge filtering: A comparative study." PLOS ONE 20, no. 1 (2025): e0316141. https://doi.org/10.1371/journal.pone.0316141.
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The backbone extraction process is pivotal in expediting analysis and enhancing visualization in network applications. This study systematically compares seven influential statistical hypothesis-testing backbone edge filtering methods (Disparity Filter (DF), Polya Urn Filter (PF), Marginal Likelihood Filter (MLF), Noise Corrected (NC), Enhanced Configuration Model Filter (ECM), Global Statistical Significance Filter (GloSS), and Locally Adaptive Network Sparsification Filter (LANS)) across diverse networks. A similarity analysis reveals that backbones extracted with the ECM and DF filters exhibit minimal overlap with backbones derived from their alternatives. Interestingly, ordering the other methods from GloSS to NC, PF, LANS, and MLF, we observe that each method’s output encapsulates the backbone of the previous one. Correlation analysis between edge features (weight, degree, betweenness) and the test significance level reveals that the DF and LANS filters favor high-weighted edges while ECM assigns them lower significance to edges with high degrees. Furthermore, the results suggest a limited influence of the edge betweenness on the filtering process. The backbones global properties analysis (edge fraction, node fraction, weight fraction, weight entropy, reachability, number of components, and transitivity) identifies three typical behavior types for each property. Notably, the LANS filter preserves all nodes and weight entropy. In contrast, DF, PF, ECM, and GloSS significantly reduce network size. The MLF, NC, and ECM filters preserve network connectivity and weight entropy. Distribution analysis highlights the PU filter’s ability to capture the original weight distribution. NC filter closely exhibits a similar capability. NC and MLF filters excel for degree distribution. These insights offer valuable guidance for selecting appropriate backbone extraction methods based on specific properties.
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Zhang, Xiaohong. "On Some Fuzzy Filters in Pseudo-BCIAlgebras." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/718972.
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Some new properties of fuzzy associative filters (also known as fuzzy associative pseudo-filters), fuzzyp-filter (also known as fuzzy pseudo-p-filters), and fuzzya-filter (also known as fuzzy pseudo-a-filters) in pseudo-BCIalgebras are investigated. By these properties, the following important results are proved: (1) a fuzzy filter (also known as fuzzy pseudo-filters) of a pseudo-BCIalgebra is a fuzzy associative filter if and only if it is a fuzzya-filter; (2) a filter (also known as pseudo-filter) of a pseudo-BCIalgebra is associative if and only if it is ana-filter (also call it pseudo-afilter); (3) a fuzzy filter of a pseudo-BCIalgebra is fuzzya-filter if and only if it is both a fuzzyp-filter and a fuzzyq-filter.
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Namdar, A. "Fuzzy n-fold fantastic filters on hoop algebras." Journal of Algebraic Hyperstructures and Logical Algebras 4, no. 2 (2023): 189–203. http://dx.doi.org/10.61838/kman.jahla.4.2.12.
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In this paper, first we introduce the concept of fuzzy n-fold positive implicative filters on hoop algebras and study some of properties. Next we define and study fuzzy n-fold fantastic filters on hoop algebras. Also, the relationship between fuzzy n-fold positive implicative filter and some other fuzzy filters likeness fuzzy n-fold implicative filter and fuzzy n-fold fantastic filters are investigated for example every fuzzy n-fold implicative filter is a fuzzy n-fold positive implicative filter on hoop algebras. Then we obtain some condition equivalent with fuzzy n-fold fantastic filters and every fuzzy filter on chain hoop algebra is a fuzzy n-fold fantastic filter. Finally we show that the quotient of fuzzy n-fold fantastic filters is a Boolean algebra.
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Jurisic Bellotti, Maja, and Mladen Vucic. "Sparse FIR Filter Design Based on Signomial Programming." Elektronika ir Elektrotechnika 26, no. 1 (2020): 40–45. http://dx.doi.org/10.5755/j01.eie.26.1.23560.
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The goal of sparse FIR filter design is to minimize the number of nonzero filter coefficients, while keeping its frequency response within specified boundaries. Such a design can be formally expressed via minimization of l0-norm of filter’s impulse response. Unfortunately, the corresponding minimization problem has combinatorial complexity. Therefore, many design methods are developed, which solve the problem approximately, or which solve the approximate problem exactly. In this paper, we propose an approach, which is based on the approximation of the l0-norm by an lp-norm with 0 < p < 1. We minimize the lp-norm using recently developed method for signomial programming (SGP). Our design starts with forming a SGP problem that describes filter specifications. The optimum solution of the problem is then found by using iterative procedure, which solves a geometric program in each iteration. The filters whose magnitude responses are constrained in minimax sense are considered. The design examples are provided illustrating that the proposed method, in most cases, results in filters with higher sparsity than those of the filters obtained by recently published methods.
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Rietjens, Judith AC, Wichor M. Bramer, Eric CT Geijteman, Agnes van der Heide, and Wendy H. Oldenmenger. "Development and validation of search filters to find articles on palliative care in bibliographic databases." Palliative Medicine 33, no. 4 (2019): 470–74. http://dx.doi.org/10.1177/0269216318824275.
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Background: Healthcare professionals and researchers in the field of palliative care often have difficulties finding relevant articles in online databases. Standardized search filters may help improve the efficiency and quality of such searches, but prior developed filters showed only moderate performance. Aim: To develop and validate a specific search filter and a sensitive search filter for the field of palliative care. Design: We used a novel, objective method for search filter development. First, we created a gold standard set. This set was split into three groups: term identification, filter development, and filter validation set. After creating the filters in PubMed, we translated the filters into search filters for Ovid MEDLINE, Embase, CINAHL, PsychINFO, and Cochrane Library. We calculated specificity, sensitivity and precision of both filters. Results: The specific filter had a specificity of 97.4%, a sensitivity of 93.7%, and a precision of 45%. The sensitive filter had a sensitivity of 99.6%, a specificity of 92.5%, and a precision of 5%. Conclusion: Our search filters can support literature searches in the field of palliative care. Our specific filter retrieves 93.7% of relevant articles, while 45% of the retrieved articles are relevant. This filter can be used to find answers to questions when time is limited. Our sensitive filter finds 99.6% of all relevant articles and may, for instance, help conducting systematic reviews. Both filters perform better than prior developed search filters in the field of palliative care.
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Jun, Y. B. "Implicative filters of equality algebras treated as fuzzy points." Journal of Algebraic Hyperstructures and Logical Algebras 6, no. 1 (2025): 13–26. https://doi.org/10.61838/kman.jahla.6.1.2.
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The notion of fuzzy points is used to study implicative filters in equality algebras. The concept of implicative (∈, ∈)-fuzzy filters is introduced, and its properties are investigated. The relationship between (∈, ∈)-fuzzy filters, implicative (∈, ∈)- fuzzy filters and positive implicative (∈, ∈)-fuzzy filters are established. Characterizations of implicative (∈, ∈)-fuzzy filters are discussed, and the conditions for the (positive implicative) (∈, ∈)-fuzzy filter to be an implicative (∈, ∈)-fuzzy filter are explored. The extension property for the implicative (∈, ∈)- fuzzy filter is established. The properties associated with ∈tset and qt-set of a fuzzy set Ψ in E and also look for conditions under which they can become implicative filters are examined.
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Avram, Sebastian, and Radu Vasiu. "Passive Power Line Communication Filter Design and Benchmarking Using Scattering Parameters." Applied Sciences 13, no. 11 (2023): 6821. http://dx.doi.org/10.3390/app13116821.
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NB-PLC (narrowband power line communication) is a method of data communication that involves superimposing a relatively high-frequency signal (9 kHz to 500 kHz), which contains data, onto the power grid’s low frequency (50 to 60 Hz) signal. While using the existing power grid as a transmission medium is convenient, the power grid was not designed for this purpose, leading to challenges such as conducted emissions and infrastructure limitations. To overcome these technical challenges, passive filters are necessary. This article presents the design, simulation (using scattering parameters), and evaluation of an NB-PLC filter by comparing it to commercially available filters. Our proposed design and benchmarking methods enable the accurate prediction of the filter’s behavior in field conditions. After comparing our filter with commercially available filters, we observed that it exhibits superior characteristics. Specifically, our filter has the best insertion loss versus frequency, achieved three times higher attenuation at 50 kHz (−130 dB) compared to the best commercially available filter (−40 dB), and has a power consumption of 0.6 W, which is comparable to the most power-efficient commercial filter (0.5 W). Additionally, our filter has the second best input and output impedance of 3.6 Ω within the frequency range of 35–95 kHz.
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Jun, Young Bae, Sun Shin Ahn, and Kyoung Ja Lee. "Classes of Int-Soft Filters in Residuated Lattices." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/595160.
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The notions of int-soft filters, int-softG-filters, regular int-soft filters, andMV-int-soft filters in residuated lattices are introduced, and their relations, properties, and characterizations are investigated. Conditions for an int-soft filter to be an int-softG-filter, a regular int-soft filter, or anMV-int-soft filter are provided. The extension property for an int-softG-filter is discussed. Finally, it is shown that the notion of anMV-int-soft filter coincides with the notion of a regular int-soft filter inBL-algebras.
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Duncan, Guy, and Greg Beresford. "Some analyses of 2-D median f-k filters." GEOPHYSICS 60, no. 4 (1995): 1157–68. http://dx.doi.org/10.1190/1.1443844.
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Two‐dimensional median filters can be designed so that they have properties similar to f-k fan filters. This is done by using the coefficients of a truncated impulse response of an f-k filter as the weight coefficients for the weighted median process. The filter is called a median f-k filter and can be used to discriminate between events on the basis of apparent velocity. The filter appears suitable as a poststack coherency filter because it produces less distortion at wavefield terminations than conventional f-k fan filters. One‐dimensional weighted median filters that include negative coefficients are a logical starting point for the analysis of median f-k filters since simple numerical techniques may be used to analyze the behavior of these filters. We show that median filters with negative coefficients do not provide an unbiased estimate of the mean and can misplace the position of steps. Faults on a stacked section may be modeled by steps, and therefore applying a median f-k filter to stacked seismic data could change the position of faults. However, the distortion of steps introduced by median f-k filters is shown to be less than the distortion produced by the corresponding linear f-k filter, and the error in step placement is small. We present simple model examples and a seismic field data example to illustrate differences between linear f-k filters and median f-k filters.
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Khriji, L. "Vector Directional Distance Rational Hybrid Filters for Color Image Restoration." Journal of Engineering Research [TJER] 2, no. 1 (2005): 1. http://dx.doi.org/10.24200/tjer.vol2iss1pp1-12.
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A new class of nonlinear filters, called vector-directional distance rational hybrid filters (VDDRHF) for multispectral image processing, is introduced and applied to color image-filtering problems. These filters are based on rational functions (RF). The VDDRHF filter is a two-stage filter, which exploits the features of the vector directional distance filter (VDDF), the center weighted vector directional distance filter (CWVDDF) and those of the rational operator. The filter output is a result of vector rational function (VRF) operating on the output of three sub-functions. Two vector directional distance (VDDF) filters and one center weighted vector directional distance filter (CWVDDF) are proposed to be used in the first stage due to their desirable properties, such as, noise attenuation, chromaticity retention, and edges and details preservation. Experimental results show that the new VDDRHF outperforms a number of widely known nonlinear filters for multi-spectral image processing such as the vector median filter (VMF), the generalized vector directional filters (GVDF) and distance directional filters (DDF) with respect to all criteria used.
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SHUI, PENG-LANG, and XIAO-LONG WANG. "2M-BAND INTERLEAVED DFT MODULATED FILTER BANKS WITH PERFECT RECONSTRUCTION." International Journal of Wavelets, Multiresolution and Information Processing 06, no. 04 (2008): 499–520. http://dx.doi.org/10.1142/s021969130800246x.
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In this paper, we propose a new family of perfect reconstruction (PR) complex filter banks, named interleaved discrete Fourier transform modulated filter banks (Interleaved DFT-FBs). In the filter banks, the analysis filters are generated by interlaced exponential modulating two different analysis prototype filters, and the synthesis filters are generated by two different synthesis prototype filters via the same manner. The filter banks have a simple polyphase structure similar to DFT modulated filter banks (DFT-FBs). More importantly, the proposed Interleaved DFT-FBs can achieve critically sampled PR complex filter bank with FIR analysis and synthesis filters, which is impossible for DFT-FBs. We give and prove the PR condition for 2M-band Interleaved DFT-FBs. Utilizing the result, the design procedure of the prototype filters is presented. In addition, by the theoretic analysis and numerical examples, it is shown that the analysis and synthesis filters cannot simultaneously provide good stopband attenuation for the critically sampled PR Interleaved DFT-FBs. Although the limitation always exits, the filter banks can find applications in some subband coding systems of high bit rate.
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Maharta Pemayun, A. A. Gede, I. Nym Budiastra, and I. W. Rinas. "ANALISIS EFESIENSI TRAFO DAYA TERHADAP PENGOPERASIAN BEBERAPA JENIS HARMONIC FILTER." Jurnal SPEKTRUM 7, no. 4 (2020): 76. http://dx.doi.org/10.24843/spektrum.2020.v07.i04.p10.
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Nonlinear load is one of the causes of harmonics in utility systems. To reduce harmonicdistortion that appears, usually in utility systems, Harmonic Filters are operated such as:passive filters, active filters, series hybrid filters and hybrid shunt filters. Harmonic distortion thatoccurs will increase losses in the utility system. Losses that appear will affect the efficiency ofthe Power transformer being operated. From the analysis results, the order of the best to worstfilter efficiency is hybride filter (? = 97.26%), active filter (? = 96.72%) and passive filter (? =95.73%).
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Li, Luping, Lijuan Dong, Peng Chen, and Kai Yang. "A low insertion loss low-pass filter based on single comb-shaped spoof surface plasmon polaritons." International Journal of Microwave and Wireless Technologies 11, no. 08 (2019): 792–96. http://dx.doi.org/10.1017/s1759078719000564.
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AbstractThis paper presents a low insertion loss low-pass filter based on the spoof surface plasmon polariton (SSPP) with single comb-shape. Compared with traditional ones, the proposed filter provides lower insertion loss and return loss by optimizing the structural parameters of the mode conversion and SSPP parts. According to the measurement results, the average insertion loss of the fabricated filter is 0.41 dB and the return loss of which at the near-zero-hertz band is &lt;−25.9 dB. The S parameter comparison result between the unoptimized and optimized filters demonstrates that the optimized filter provides lower insertion loss and return loss, smaller size, and better out-of-band rejection. The dispersion comparison result reveals the reasons behind the improved performances. The better performances of the optimized filter proves that breaking the regularity of traditional SSPP filters is beneficial to the filter's performances.
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Schauland, Sam, Joerg Velten, and Anton Kummert. "Detection of Moving Objects in Image Sequences using 3D Velocity Filters." International Journal of Applied Mathematics and Computer Science 18, no. 1 (2008): 21–31. http://dx.doi.org/10.2478/v10006-008-0002-2.
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Detection of Moving Objects in Image Sequences using 3D Velocity FiltersA movement analysis of objects contained in visual scenes can be performed by means of linear multidimensional filters, which have already been analyzed in the past. While the soundness of the results was convincing, interest in those systems declined due to the limited computational power of contemporary computers. Recent advances in design and implementation of integrated circuits and hardware architectures allow realizing velocity filters if then-D system is carefully adapted to the analyzed problem. In this paper, the fundamental principles of visual scene analysis by linear multidimensional filters are examined with respect to possible sources of degradation. The extraction of movement information and its practical use are demonstrated using a wave digital filter (WDF) implementation.
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Wang, Zixuan. "Different Methods of Linear Phase IIR Filer Realization." Highlights in Science, Engineering and Technology 27 (December 27, 2022): 167–71. http://dx.doi.org/10.54097/hset.v27i.3739.
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Signal processing has become one of the most popular research topics. Researchers have designed a variety of digital filters to exclude unwanted random noises during the transmission or extract part of the signal in the desired range. There is a prevalent trend for digital filters to replace analog ones since they do not require hardwires. All the performances are operated on a single processor and are free from the effect of external factors. Finite impulse response (FIR) and infinite impulse response (IIR) filters in digital filters respectively provide infinite and finite impulse responses. In the application, it is preferred to have a linear phase digital filter, and FIR filters are naturally linear. However, FIR filters have higher orders and group delay than IIR filters, so researchers found various ways to implement linear phase IIR filters for improvement. This paper introduces and compares Powell and Chau Linear Phase IIR Filter, Kwan Linear Phase IIR Filter, and Xiao, Oliver, and Agathoklis Linear Phase IIR Filter.
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Parameshappa, G., and D. Jayadevapp. "Efficient uniform digital filter bank with linear phase and FRM technique for hearing aids." International Journal of Engineering & Technology 7, no. 1.9 (2018): 69. http://dx.doi.org/10.14419/ijet.v7i1.9.9738.
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This paper attempts to present an uniform digital filter bank based on linear phase FIR and IIR filters applied for Frequency Response Masking (FRM) technique in hearing aid applications.In the proposed filter bank, nine uniformly spaced sub-bands are formed with the help of half band filters and masking filters. These nine channel FIR filter bank is realized using an interpolated half band linear phase FIR filter and an appropriate number of masking FIR filters. The nine channel IIR filter bank is realized using an interpolated half band approximately linear phase IIR filter and an appropriate number of masking filters. The proposed approximately linear phase IIR half band filter bank is compared with filter bank based on linear phase FIR half band filters in terms of area, power, memory and number of gates needed for implementation. The experiment was carried on various hearing loss cases and the results obtained from these tests proves that, the proposed filter bank achieved the required matching between audiograms and magnitude response of the filter bank at very reasonable range with less computational complexity.
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Lu, Hao, Xiaorun Hao, Ling Yang, et al. "Recent Advances in AlN-Based Acoustic Wave Resonators." Micromachines 16, no. 2 (2025): 205. https://doi.org/10.3390/mi16020205.
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AlN-based bulk acoustic wave (BAW) filters have emerged as crucial components in 5G communication due to their high frequency, wide bandwidth, high power capacity, and compact size. This paper mainly reviews the basic principles and recent research advances of AlN-based BAW resonators, which are the backbone of BAW filters. We begin by summarizing the epitaxial growth of single-crystal, polycrystalline, and doped AlN films, with a focus on single-crystal AlN and ScAlN, which are currently the most popular. The discussion then extends to the structure and fabrication of BAW resonators, including the basic solidly mounted resonator (SMR) and the film bulk acoustic resonator (FBAR). The new Xtended Bulk Acoustic Wave (XBAW) technology is highlighted as an effective method to enhance filter bandwidth. Hybrid SAW/BAW resonators (HSBRs) combine the benefits of BAW and SAW resonators to significantly reduce temperature drift. The paper further explores the application of BAW resonators in ladder and lattice BAW filters, highlighting advancements in their design improvements. The frequency-reconfigurable BAW filter, which broadens the filter’s application range, has garnered substantial attention from researchers. Additionally, optimization algorithms for designing AlN-based BAW filters are outlined to reduce design time and improve efficiency. This work aims to serve as a reference for future research on AlN-based BAW filters and to provide insight for similar device studies.
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Malleswari, V. S. Naga, G. Luka, Bhagyalakshmi Kothuru, T. Srinivasa Rao, and V. Amarendra Babu. "Application of Neutrosophic implicative filters and Neutrosophic positive implicative filters in Lattice implication algebra." International Journal of Neutrosophic Science 21, no. 1 (2023): 69–79. http://dx.doi.org/10.54216/ijns.210106.
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We introduced Neutrosophic implicative filters and Neutrosophic positive implicative filters in Lattice implication algebra. We proved some properties and equivalent conditions of both the filters. Finally we proved that “Every Neutrosophic positive implicative filter is a Neutrosophic implicative filter” and “Every Neutrosophic positive implicative filter is a Neutrosophic filter”.
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Kaufman, Amanda R., Lisa M. Casanova, and Mark D. Sobsey. "Efficacy of a ceramic siphon household water filter for removal of pathogenic microorganisms: lifespan volume test." Journal of Water, Sanitation and Hygiene for Development 1, no. 2 (2011): 102–11. http://dx.doi.org/10.2166/washdev.2011.037.
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Treatment of drinking water at the point of use (POU) has demonstrated health benefits for people who have access only to microbially contaminated drinking water. In this work, the ceramic siphon POU water filter was evaluated for its ability to reduce indicator microorganisms in test waters. During batch challenge tests, the filter reduced Escherichia coli in filtered water by 7 log10 (99.999987%) and bacteriophage MS2 by 0.12 log10 (24.0%). Next, a novel continuous flow dosing system allowing sewage-amended feed water to constantly pass through the filters allowed for determination of changes in microbial reductions over time and total volume of water filtered. E. coli B, MS2 and fluorescent microspheres (as a surrogate for Cryptosporidium oocysts) were seeded into test water and dosed to filters at 10, 25 and 50% of the filter's volume lifespan. Microbial removal efficacy decreased as the volume of water filtered increased and test filters did not achieve their volume lifespan before physically failing. The ceramic siphon household water filter is effective in reducing E. coli and surrogates for Cryptosporidium in water, but filter modifications may be needed to achieve acceptable levels of virus removal and to reach the target 7,000 L volume lifespan of the filter.
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Smirnov, A. V. "Optimization of digital filters performances simultaneously in frequency and time domains." Russian Technological Journal 8, no. 6 (2020): 63–77. http://dx.doi.org/10.32362/2500-316x-2020-8-6-63-77.
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Wide used method of digital filters design consists in transformation of analog filter-prototype with required performances into digital filter. This method is applicable if the transformation preserves optimality of filter performances under specified set of quality indexes (QI). It was denoted earlier that such situation is possible when gain-frequency response (GFR) and phase-frequency response are optimized simultaneously. The task of simultaneous optimization of digital filters GFR and step response (SR) is also important but yet a little explored. Alternative method of this problem solving consists in search of digital filter transfer function (TF) which is optimal under GFR and SR QI’s. To investigate capabilities of the first method we found examples of analog filters Pareto-optimal under rise time and transient duration. Other QI’s of these filters fulfilled specified constraints. Then these filters were transformed into digital filters. Bilinear transformation and transformation with invariant impulse response were applied. Further we did the search of digital filters optimal under the same set of QI’s. In either method the hybrid heuristic algorithm was applied for search optimal solutions in the space of TF poles and zeroes coordinates. The results of investigation demonstrated that digital filters developed via search are superiorly under specified set of QI’s then digital filters developed via transformation of analog filters. Accordingly Pareto-optimality for QI of GFR and SR is not preserved during such transformation and direct search must be applied to optimized digital filters simultaneously in frequency and time domains. Further in some cases analog filters developed via reverse bilinear transformation of the found optimal digital filters are superiorly under the same set of QI’s then analog filters developed using search. In such cases using of digital filter-prototypes for design of analog filters is practical.
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Xin, Xiao Long, Peng Fei He, and Yong Wei Yang. "Characterizations of Some Fuzzy Prefilters (Filters) inEQ-Algebras." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/829527.
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We introduce and study some types of fuzzy prefilters (filters) inEQ-algebras. First, we present several characterizations of fuzzy positive implicative prefilters (filters), fuzzy implicative prefilters (filters), and fuzzy fantastic prefilters (filters). Next, using their characterizations, we mainly consider the relationships among these special fuzzy filters. Particularly, we find some conditions under which a fuzzy implicative prefilter (filter) is equivalent to a fuzzy positive implicative prefilter (filter). As applications, we obtain some new results about classical filters inEQ-algebras and some related results about fuzzy filters in residuated lattices.
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Park, Jang Jin, Jin Myung Shin, Jae Hwan Yang, Young Hee Baek, and Geun Il Park. "Fabrication and performance of fl y ash granule filter for trapping gaseous cesium." Nukleonika 60, no. 3 (2015): 565–70. http://dx.doi.org/10.1515/nuka-2015-0104.
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Abstract Although a disk-type fly ash filter has shown a good performance in trapping gaseous cesium, it has difficulty in charging filters into a filter container and discharging waste filters containing radioactive cesium from a container by remote action. To solve the difficulty of the disk-type fly ash filter, five types of granule filters, including a ball type, tube type, and sponge-structure type have been made. Among them, the best filter type was chosen through simple crucible tests. The five types of granule filters packed into containers were loaded into five alumina crucibles of 50 cc. Five grams of CsNO3 was used as a gaseous cesium source. They were then placed in a muffle furnace and heated to 900°C and maintained for 2 hours. After the experiment, the weights of the cesium trapped filters were measured. Among the five types of granule filters, the sponge-structure type granule filter was the best, which has the highest trapping capacity of cesium. Its capacity is 0.42 g-Cs/g-filter. The chosen sponge-structure type granule filters and disk-type filters have been tested using a two-zone tube furnace. Cs volatilization and Cs trapping zones were maintained at 900 and 1000°C, respectively. Sixteen grams of CsNO3 was used as a gaseous cesium source. The cesium trapping profile of the sponge-structure type granule filters was almost similar to that of the disk-type fly ash filters. For both cases, cesium was successfully trapped within the third filter.
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Satyanarayana, Dr S. V. V., K. Teja Sri, K. Madhavi, G. Jhansi, and B. Jaya Sri. "Design and Implementation of High Speed Low Power Decimation Filter for Hearing AID Applications." International Journal of Recent Technology and Engineering (IJRTE) 12, no. 1 (2023): 27–32. http://dx.doi.org/10.35940/ijrte.a7564.0512123.
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This work is focused on designing and implementing a decimation filter specifically intended for use in hearing aid applications. The filter utilizes distributed arithmetic (DA) and is described in this brief. Our proposal involves the development of a reconfigurable finite impulse response (FIR) filter, which utilizes both offset binary code (OBC) and binary distributed arithmetic (DA) techniques. Additionally, we utilize canonic signed digit (CSD) representation to develop decimation filters, which include the CIC filter, half band filter, and corrector filter. In this work, we have implemented a decimation filter using Matlab Simulink. We have utilized Xilinx Vivado 19.2 to execute the FIR filters, binary DA filters, and OBC DA-based filters. Our focus is on implementing these filters using VLSI architecture, in order to achieve low power consumption, reduced latency, less area, and fast speed.
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Sotelo, Diana C., Nancy Ornelas-Soto, and Johann F. Osma. "Novel Magnetic Polymeric Filters with Laccase-Based Nanoparticles for Improving Congo Red Decolorization in Bioreactors." Polymers 14, no. 12 (2022): 2328. http://dx.doi.org/10.3390/polym14122328.
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In this work, five different magnetic biofilters, containing magnetic nanoparticles (142 nm), immobilized laccase on nanoparticles (190 nm) and permanent magnetic elements, such as neodymium magnets and metallic meshes, were designed, manufactured and tested. The five types of filters were compared by measuring the decolorization of Congo Red dye inside bioreactors, the half-life of the filters and the amount of magnetic nanoparticle and enzyme lost during multiple cycles of operation. Filters containing laccase immobilized on magnetite (Laccase-magnetite), permanent magnets and metallic mesh presented the highest Congo Red decolorization (27%) and the largest half-life among all types of filters (seven cycles). The overall dye decolorization efficiencies were 5%, 13%, 17%, 23%, and 27% for the paper filter, paper filter with magnetite, paper filter with Laccase-magnetite, paper filter with Laccase-magnetite with magnets and paper filter with Laccase-magnetite with magnets and metallic mesh, respectively. Although the highest losses of magnetite occurred when using the filters containing magnets (57 mg), the use of permanent magnetic elements in the filters increased the half-life of the filter three-fold compared to the filters without enzymatic properties and two-fold compared to the filters with Laccase-magnetite. Results indicate that the novel use of permanent magnetic elements improved the nanoparticle retention in the filters and promoted the mass transfer between the dye and the biocatalyst to enhance wastewater treatment.
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PAI, K. R., K. V. V. MURTHY, and V. RAMACHANDRAN. "COMPLEMENTARY POLE-PAIR FILTERS AND POLE-PARAMETER TRANSFORMATIONS." Journal of Circuits, Systems and Computers 06, no. 04 (1996): 319–50. http://dx.doi.org/10.1142/s0218126696000224.
Full textAbstract:
It is well known that the poles of a Butterworth filter (BF) are uniformly placed on the unit circle in the s-plane. If the order of the filter is a binary power (i.e., n=2k, k being an integer), then the pole-locations of such Butterworth filters exhibit very interesting symmetry properties in the s-plane. In this paper, first we point out that the pole-vectors of the Butterworth filters (of order n=2k) can be subjected to “prescribed symmetrical swinging”, such that certain symmetry properties present in the original pole-pattern can be maintained invariant. Then, we introduce a new family of filters called “Complementary Pole-Pair Filters (CPPFs)”, generated by judiciously exploiting the symmetry-invariant property referred to above. The Q-constraint can be easily incorporated into the design considerations of the new family of filters; accordingly, the CPPFs are classified as Low-Q filters (LQFs) and High-Q Filters (HQFs). Performances of LQFs and HQFs are analyzed and compared with that of the generic Butterworth filter. Also, the possibility of generating additional transitional filters is indicated. Design constraints are derived. Numerical examples are worked out for illustrations. A new transformation referred to as the “Pole-Parameter Transformation (PPT)”, which modifies the pole-parameters of a given reference filter to obtain a low-Qp filter, but with increased order of complexity, is formulated. This enables us to generate new families of Transitional Filters. The transitional nature involved between Butterworth and Chebyshev filters is brought out. The performance of new filters obtained are compared with those available in the literature. The CPP Filters coupled with the PPT provide a basis for generating a large family of transitional filters, and serves to commendably place the known classical filters as particular members of a large general family.
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Prijono, Wahju Adi, and Naufal Kurnia Rizki. "Perencanaan Rancang Bangun Microstrip Band Pass Filter dengan Struktur Tapped Input Hairpin pada Aplikasi Jaringan Mid-band 5G Telkomsel." Jurnal EECCIS (Electrics, Electronics, Communications, Controls, Informatics, Systems) 16, no. 1 (2022): 20–23. http://dx.doi.org/10.21776/jeeccis.v16i1.1492.
Full textAbstract:
Microstrip filter is a type of Radio Frequency (RF) filter that uses a thin electrical conductor separated from the ground plane by using a dielectric called the substrate. Microstrip filters are generally printed on Printed Circuit Boards or PCBs where high-frequency signals are directed from one part of the system to another with high efficiency. There are several types that can be applied to the operation of microstrip filters, one of which is a band pass filter. Band pass filter is a filter that can pass a signal with a certain frequency that is limited by a low cut-off frequency and a high cut-off frequency, and is able to dampen signals that are below the cut-off frequency and above the high cut-off frequency. There are several types of resonator designs that can be used for reference in the manufacture of microstrip filters, such as tapped line input hairpin filters, stub loaded filters, stepped impedance filters, and combline filters. By using the reference form of the tapped line input hairpin, this journal is intended for planning the manufacture of microstrip filters in the application of Telkomsel's 5G technology.
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Biradar, Nagashettappa, M. L. Dewal, and Manoj Kumar Rohit. "Edge Preserved Speckle Noise Reduction Using Integrated Fuzzy Filters." International Scholarly Research Notices 2014 (October 30, 2014): 1–11. http://dx.doi.org/10.1155/2014/876434.
Full textAbstract:
Echocardiographic images are inherent with speckle noise which makes visual reading and analysis quite difficult. The multiplicative speckle noise masks finer details, necessary for diagnosis of abnormalities. A novel speckle reduction technique based on integration of geometric, wiener, and fuzzy filters is proposed and analyzed in this paper. The denoising applications of fuzzy filters are studied and analyzed along with 26 denoising techniques. It is observed that geometric filter retains noise and, to address this issue, wiener filter is embedded into the geometric filter during iteration process. The performance of geometric-wiener filter is further enhanced using fuzzy filters and the proposed despeckling techniques are called integrated fuzzy filters. Fuzzy filters based on moving average and median value are employed in the integrated fuzzy filters. The performances of integrated fuzzy filters are tested on echocardiographic images and synthetic images in terms of image quality metrics. It is observed that the performance parameters are highest in case of integrated fuzzy filters in comparison to fuzzy and geometric-fuzzy filters. The clinical validation reveals that the output images obtained using geometric-wiener, integrated fuzzy, nonlocal means, and details preserving anisotropic diffusion filters are acceptable. The necessary finer details are retained in the denoised echocardiographic images.