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Journal articles on the topic 'Ground filter'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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Díaz Pardo, Iván Eduardo, Carlos Arturo Suárez Fajardo, and Gustavo Adolfo Puerto Leguizamón. "A study of the ground plane effect in passband filters using OSRR cells." DYNA 82, no. 193 (2015): 9–15. http://dx.doi.org/10.15446/dyna.v82n193.42550.

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This paper presents the study of the ground plane effect in passband filters using metamaterial cells in Open Split Ring Resonators (OSRR) structures on microstrip substrates. Three different configurations have been proposed, namely: by removing partially the ground plane of the OSRR cell back end, by windows design over the ground plane at the back end of each cell and by placing a full ground plane. The conducted analysis shows that the filter transmission response featuring a ground plane including windows proved to be the most flattened with the middle bandwidth of the three configurations. On the other hand, the performance of these filters is similar to a conventional filter based on three-pole microstrip technology but with a considerable reduction in size of about 60%.

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Kitamura, Toshiaki. "Comb-Line Filter with Coupling Capacitor in Ground Plane." Active and Passive Electronic Components 2011 (2011): 1–6. http://dx.doi.org/10.1155/2011/919240.

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A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs) are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

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Justa, Josef, Václav Šmídl, and Aleš Hamáček. "Fast AHRS Filter for Accelerometer, Magnetometer, and Gyroscope Combination with Separated Sensor Corrections." Sensors 20, no. 14 (2020): 3824. http://dx.doi.org/10.3390/s20143824.

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A new predictor–corrector filter for attitude and heading reference systems (AHRS) using data from an orthogonal sensor combination of three accelerometers, three magnetometers and three gyroscopes is proposed. The filter uses the predictor—corrector structure, with prediction based on gyroscopes and independent correction steps for acceleration and magnetic field sensors. We propose two variants of the filter: (i) one using mathematical operations of special orthogonal group SO(3), that are accurate for nonlinear operations, for highest possible accuracy, and (ii) one using linearization of nonlinear operations for fast evaluation. Both approaches are quaternion-based filter realizations without redundant steps. The filters are compared to state of the art methods in this field on data recorded using low-cost microelectromechanical systems (MEMS) sensors with ground truth measured by the VICON optical system. Both filters achieved better accuracy than conventional methods at lower computational cost. The recorded data with ground truth reference and the source codes of both filters are publicly available.

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Nedelchev, M., and A. Kolev. "Synthesis of Planar Filters Using Defected Ground Structure Miniaturized Hairpin Resonators." Engineering, Technology & Applied Science Research 9, no. 1 (2019): 3734–38. http://dx.doi.org/10.48084/etasr.2424.

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This paper presents an effective technique to suppress the spurious passbands in planar filters by using defected ground structure (DGS) resonators etched in the ground plane. The proposed miniaturized hairpin DGS slot resonator is researched in terms of its resonance frequency, corresponding coupling topologies, and filter design. The resonator and the topologies of coupled DGS resonators are simulated in a fullwave electromagnetic (EM) simulator. Using a curve-fitting technique, useful design formulas are proposed for filter synthesis. Using the synthesis procedure, a 3rd order filter design is simulated, manufactured and measured. The insertion loss of -3dB in the passband of 280MHz is observed, while the suppression of the spurious passbands up to 12GHz is more than 24dB.

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Talybova, J. "Selection of Drainage and Evaluation Used Filter Media." Bulletin of Science and Practice 6, no. 3 (2020): 161–69. http://dx.doi.org/10.33619/2414-2948/52/16.

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The feature of running the suffosion of sand grounds in the top five-meter soil-ground layer where drainage is constructed on the basis of existing normative documents and granulo¬metric composition of filter material was determined with reports. The actual and report contents of the filter differ sharply. Large particles (40% by weight) of more than 20 mm should be sorted out from the sand-gravel ground to be used for construction of drainage.

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Štular, Benjamin, and Edisa Lozić. "Comparison of Filters for Archaeology-Specific Ground Extraction from Airborne LiDAR Point Clouds." Remote Sensing 12, no. 18 (2020): 3025. http://dx.doi.org/10.3390/rs12183025.

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Identifying bare-earth or ground returns within point cloud data is a crucially important process for archaeologists who use airborne LiDAR data, yet there has thus far been very little comparative assessment of the available archaeology-specific methods and their usefulness for archaeological applications. This article aims to provide an archaeology-specific comparison of filters for ground extraction from airborne LiDAR point clouds. The qualitative and quantitative comparison of the data from four archaeological sites from Austria, Slovenia, and Spain should also be relevant to other disciplines that use visualized airborne LiDAR data. We have compared nine filters implemented in free or low-cost off-the-shelf software, six of which are evaluated in this way for the first time. The results of the qualitative and quantitative comparison are not directly analogous, and no filter is outstanding compared to the others. However, the results are directly transferable to real-world problem-solving: Which filter works best for a given combination of data density, landscape type, and type of archaeological features? In general, progressive TIN (software: lasground_new) and a hybrid (software: Global Mapper) commercial filter are consistently among the best, followed by an open source slope-based one (software: Whitebox GAT). The ability of the free multiscale curvature classification filter (software: MCC-LIDAR) to remove vegetation is also commendable. Notably, our findings show that filters based on an older generation of algorithms consistently outperform newer filtering techniques. This is a reminder of the indirect path from publishing an algorithm to filter implementation in software.

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Smith, P. G., A. Gaber, I. Hattab, and H. A. Halim. "A Study into the Removal of Iron from Ferruginous Ground Water Using Limestone Bed Filtration." Water Science and Technology 27, no. 9 (1993): 23–28. http://dx.doi.org/10.2166/wst.1993.0174.

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A pilot plant consisting of limestone bed filtration and sand filtration has been built 15 km south of Cairo to serve about 400 people. The pilot plant consists of 3 limestone filter units operated in series and two sand filters. The limestone filters are 1.3 m × 1.3 m and have a media depth of 1.15 m, a liquid depth of 0.5 m plus 0.35 m free board. The pilot plant started operation in April 1991 and the initial operation of the pilot plant has shown that a packed limestone filter unit is a simple and cheap method of removing iron from ferruginous groundwater. The initial results have shown that when an inlet water of about 5 mg/l of iron is treated by one limestone filter and one sand filter at a flow rate of 0.9 m3/h, the treated water had an average iron concentration of 0.2 mg/l.

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Canjar, R. Michael. "Small filter forcing." Journal of Symbolic Logic 51, no. 3 (1986): 526–46. http://dx.doi.org/10.2307/2274011.

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Qλ is the set of nonprincipal filters on ω which are generated by fewer than λ sets, for λ a fixed uncountable, regular cardinal ≤ c. We analyze forcing with Qλ, where Qλ is partially ordered in such a way that a filter F1 is more informative than F2 iff F1 includes F2. Qλ-forcing adjoins an ultrafilter on ω but adds no new reals. We analyze Qλ-forcing from a forcing-theoretic viewpoint. We also analyze the properties of Qλ-generic ultrafilters. These properties are independent of ZFC and depend very much on the ground model. In particular, we study Qλ-forcing over ground models which are Cohen real extensions, random real extensions, and models which satisfy Martin's Axiom.In §2 we give notations and definitions, and review some of the basic facts about forcing and ultrafilters which we will use. In §3 we introduce Qλ-forcing and prove some basic lemmas about it. §4 studies Qc-forcing. §§5, 6, and 7 analyze Qλ-forcing over ground models of Martin's Axiom, ground models which are generated by Cohen reals, and ground models which are generated by random reals, respectively. Qλ-forcing over Cohen real and random real models is isomorphic to the notion of forcing which adjoins a Cohen generic subset of λ; this is proved in §8.

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Li, Yong-An. "Synthesis for Butterworth Filter Using Compact VDTA Based on Sallen- Key Topology." Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 13, no. 5 (2020): 681–88. http://dx.doi.org/10.2174/2352096512666191004123213.

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Background: The original filter including grounded or virtual ground capacitors can be synthesized by using the NAM expansion. However, so far the filters including floating capacitor, such as Sallen-Key filter, have not been synthesized by means of the NAM expansion. This is a problem to be researched further. Methods: By using the adjoint network theory, the Sallen-Key filter including floating capacitor first is turned into a current-mode one, which includes a grounded capacitor and a virtual ground capacitor. Then the node admittance matrix, after derived, is extended by using NAM expansion. Results: At last, one VDTA Sallen-Key filter is received. It employs single compact VDTA and two grounded capacitors. Conclusion: A Butterworth VDTA second-order frequency filter based on Sallen-Key topology with fo = 100kHz, HLP = -HBP=1, is designed.

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Dastkhosh, Amir Reza, Gholamreza Dadashzadeh, and Mohammad Hossein Sedaaghi. "New Design Method of UWB Microstrip Filters Using Adaptive Genetic Algorithms with Defected Ground Structures." International Journal of Microwave Science and Technology 2010 (May 12, 2010): 1–9. http://dx.doi.org/10.1155/2010/671515.

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The effects of adaptive genetic algorithms (AGAs) and defected ground structures (DGSs) on performance optimization of tapered microstrip filter are investigated. The proposed structure achieves an ultra wide stopband with high attenuation within a small surface area, as well as 45% smaller size, in comparison with conventional filters. The parameters of the filter are optimized using in-home AGA code. In the proposed AGA algorithm, the crossover and mutation probabilities are adaptively changed according to the value of individual fitness. Then by utilizing the proposed DGS, a compact S-band lowpass filter with ultra-wide spurious free window is obtained. The proposed filter achieves an insertion loss of 0.8 dB from DC up to 4 GHz and 21 dB rejection in the stopband from 4.3 up to 60 GHz. The fabricated and measured results exhibit good agreement with the simulated results. They demonstrate that combining AGA and DGS yields best possible response for this group of filters.

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Kumar, A., R. Patel, and M. V. Kartikeyan. "Investigation on Microstrip Filters with CSRR Defected Ground Structure." Advanced Electromagnetics 5, no. 2 (2016): 28. http://dx.doi.org/10.7716/aem.v5i2.353.

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This paper consists the design studies of complementary split ring resonator (CSRR) defected ground structure (DGS) microstrip filter with low insertion loss in the passband and high rejection in stopband with a comparison of various CSRR-DGS structure has been proposed. Various parameters of microstrip filters have been studied with CSRR-DGS such as roll off rate, bandwidth, effective inductance and capacitance. On the basis of these studies, microstrip low-pass, bandpass and dual-band bandstop filters have been designed and realized with enhanced properties of filters.

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Zheng, Jihong, and Meiguo Gao. "Tracking Ground Targets with a Road Constraint Using a GMPHD Filter." Sensors 18, no. 8 (2018): 2723. http://dx.doi.org/10.3390/s18082723.

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The Gaussian mixture probability hypothesis density (GMPHD) filter is applied to the problem of tracking ground moving targets in clutter due to its excellent multitarget tracking performance, such as avoiding measurement-to-track association, and its easy implementation. For the existing GMPHD-based ground target tracking algorithm (the GMPHD filter incorporating map information using a coordinate transforming method, CT-GMPHD), the predicted probability density of its target state is given in road coordinates, while its target state update needs to be performed in Cartesian ground coordinates. Although the algorithm can improve the filtering performance to a certain extent, the coordinate transformation process increases the complexity of the algorithm and reduces its computational efficiency. To address this issue, this paper proposes two non-coordinate transformation roadmap fusion algorithms: directional process noise fusion (DNP-GMPHD) and state constraint fusion (SC-GMPHD). The simulation results show that, compared with the existing algorithms, the two proposed roadmap fusion algorithms are more accurate and efficient for target estimation performance on straight and curved roads in a cluttered environment. The proposed methods are additionally applied using a cardinalized PHD (CPHD) filter and a labeled multi-Bernoulli (LMB) filter. It is found that the PHD filter performs less well than the CPHD and LMB filters, but that it is also computationally cheaper.

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Ertay, Agâh Oktay, Mehmet Abbak, and Serkan Şimşek. "An improved stopband and sharp roll off microstrip low pass filter with defected ground structures." International Journal of Microwave and Wireless Technologies 8, no. 3 (2015): 573–81. http://dx.doi.org/10.1017/s175907871500094x.

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In this paper a novel low pass filter (LPF) design procedure is proposed for electromagnetic bandgap based microstrip filters without using classical filter design approach. LPF is designed for ultra-wide stopband and sharp roll-off rate via proposed design procedure. It has been shown that finite periodic fan-shaped defected ground structures (FSDGSs) and double radial stubs (DRSs) yield broad stopband and very sharp transition band. The proposed LPF has −3 dB passband from dc to 1.49 GHz, and −20 dB broad stopband from 1.65 GHz up to 7.41 GHz. Full wave electromagnetic (EM) simulation of the proposed filter is achieved with ANSYS's High Frequency Structure Simulator (HFSS) and equivalent circuit (EC) model of the filter is proposed and verified via Applied Wave Research (AWR) software. To verify the simulations, filter is realized on ARLON AD1000 substrate, and measured with Agilent 5245A PNA-X Vector Network Analyzer. Measurement results of fabricated filter are in good agreement with EM and EC simulations.

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Беляев, Б. А., С. А. Ходенков, И. В. Говорун та А. М. Сержантов. "Микрополосковые фильтры с широкими полосами пропускания". Письма в журнал технической физики 47, № 7 (2021): 30. http://dx.doi.org/10.21883/pjtf.2021.07.50796.18581.

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New microstrip designs of bandpass filters based on a low-pass filter was developed. Several or all the sections of high-impedance microstrip lines of the designed filters were connected to the ground by stubs. The filters have high frequency-selective properties, and their fractional bandwidths are in the range of 30 % –150 %. An experimental sample of a filter with a 2 GHz central frequency of the passband and 70% fractional bandwidth was made on an alumina substrate 1 mm thick. The filter has a substrate area of 46 × 21 mm2. Good agreement of the measured frequency response of the filter with the characteristics calculated by the numerical electrodynamic analysis of its 3D model was shown.

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Guo, Xing Long, Z. L. Wang, J. Huang, Z. J. Zhang, H. H. Yin, and H. F. Zhu. "Tunable Low-Pass MEMS Filter Using Defected Ground Structures (DGS)." Advanced Materials Research 712-715 (June 2013): 1798–801. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.1798.

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In this paper, fully monolithic tunable millimeter-wave filters using defected ground structures (DGS) are proposed using the CPW-based periodic structures with novel multiple-contact MEMS switches. Millimeter-wave low-pass filters were designed, fabricated, and tested. The cascaded CPW-based periodic structures, with low-pass intrinsic filtering characteristics, are reconfigured into a self-similar single unit cell by the operation of the novel multiple-contact MEMS switches with single actuation. In the first order tuning, the 3-dB cut-off frequency changes from 8.2GHz to10.5GHz, and the second order tuning is 8.2GHz to 16.8GHz. The tested results show that the pass-band ripple is less than 1.2dB and the maximal out-of-band rejection is better than 27dB. The chip size of the low-pass filter is 2.5mm×1.2mm.

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Saatçilar, Ruhi, and Nezihi Canitez. "The lattice filter in ground‐roll suppression." GEOPHYSICS 59, no. 4 (1994): 623–31. http://dx.doi.org/10.1190/1.1443622.

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Seismic reflections are sometimes masked by Ray‐leigh‐type surface waves that are termed ground roll in seismic literature. An adaptive lattice filter is used to recover reflected signals contaminated by ground roll. Experiments on synthetic and field data showed that the adaptive lattice filter technique is very effective in ground‐roll elimination. In addition, the filter works as a whitening operator, compresses the signal, and increases the signal‐to‐noise ratio.

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Rakesh Kumar Maurya, Pradyot Kala, Reena Pant,. "DEFECTED GROUND COPLANAR MULTI-BAND-PASS MICROSTRIP FILTER." INFORMATION TECHNOLOGY IN INDUSTRY 9, no. 1 (2021): 64–68. http://dx.doi.org/10.17762/itii.v9i1.102.

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This paper presents a combination of an inductive coupling technique and coplanar ground plane microstrip filter. Here, inductive coupling technique is used to overcome the unwanted radiation loss generated by the gap between the co-planar ground plane and the transmission line which improves filter characteristics. A defected ground structure (DGS) is integrated with the proposed filter to achieve a tri-bandpass characteristic (1.85, 3.53, and 5 GHz) without hampering the filter performance. The experimental results of the proposed filter are found in good agreement with simulated results.

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Štroner, Martin, Rudolf Urban, Martin Lidmila, Vilém Kolář, and Tomáš Křemen. "Vegetation Filtering of a Steep Rugged Terrain: The Performance of Standard Algorithms and a Newly Proposed Workflow on an Example of a Railway Ledge." Remote Sensing 13, no. 15 (2021): 3050. http://dx.doi.org/10.3390/rs13153050.

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Point clouds derived using structure from motion (SfM) algorithms from unmanned aerial vehicles (UAVs) are increasingly used in civil engineering practice. This includes areas such as (vegetated) rock outcrops or faces above linear constructions (e.g., railways) where accurate terrain identification, i.e., ground filtering, is highly difficult but, at the same time, important for safety management. In this paper, we evaluated the performance of standard geometrical ground filtering algorithms (a progressive morphological filter (PMF), a simple morphological filter (SMRF) or a cloth simulation filter (CSF)) and a structural filter, CANUPO (CAractérisation de NUages de POints), for ground identification in a point cloud derived by SfM from UAV imagery in such an area (a railway ledge and the adjacent rock face). The performance was evaluated both in the original position and after levelling the point cloud (its transformation into the horizontal plane). The poor results of geometrical filters (total errors of approximately 6–60% with PMF performing the worst) and a mediocre result of CANUPO (approximately 4%) led us to combine these complementary approaches, yielding total errors of 1.2% (CANUPO+SMRF) and 0.9% (CANUPO+CSF). This new technique could represent an excellent solution for ground filtering of high-density point clouds of such steep vegetated areas that can be well-used, for example, in civil engineering practice.

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Li, Bao Ping, and Yan Liang Zhang. "Novel Low-Pass Microwave Filter Based on Rectangular Ring DGS." Applied Mechanics and Materials 273 (January 2013): 371–74. http://dx.doi.org/10.4028/www.scientific.net/amm.273.371.

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Due to the frequency response periodicity of distributed transmission line, microstrip band-pass filter usually produces parasitic pass-band and outputs harmonics away from the center frequency of main pass-band. Based on the study of rectangular ring defected ground structure, a 5-order microstrip LPF(low-pass filter) was designed using the single-pole band-stop and slow-wave characteristics of the rectangular ring DGS(Defected Ground Structure) and SISS(Step-Impedance Shunt Stub) structure. Compared with traditional LPF, this LPF presents the advantages of compact size, low insertion loss, broad stop-band and high steep. It also validates the requirements of miniaturization and high performance for filters.

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Zhang, Z., M. Gerke, G. Vosselman, and M. Y. Yang. "FILTERING PHOTOGRAMMETRIC POINT CLOUDS USING STANDARD LIDAR FILTERS TOWARDS DTM GENERATION." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2 (May 28, 2018): 319–26. http://dx.doi.org/10.5194/isprs-annals-iv-2-319-2018.

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Digital Terrain Models (DTMs) can be generated from point clouds acquired by laser scanning or photogrammetric dense matching. During the last two decades, much effort has been paid to developing robust filtering algorithms for the airborne laser scanning (ALS) data. With the point cloud quality from dense image matching (DIM) getting better and better, the research question that arises is whether those standard Lidar filters can be used to filter photogrammetric point clouds as well. Experiments are implemented to filter two dense matching point clouds with different noise levels. Results show that the standard Lidar filter is robust to random noise. However, artefacts and blunders in the DIM points often appear due to low contrast or poor texture in the images. Filtering will be erroneous in these locations. Filtering the DIM points pre-processed by a ranking filter will bring higher Type II error (i.e. non-ground points actually labelled as ground points) but much lower Type I error (i.e. bare ground points labelled as non-ground points). Finally, the potential DTM accuracy that can be achieved by DIM points is evaluated. Two DIM point clouds derived by Pix4Dmapper and SURE are compared. On grassland dense matching generates points higher than the true terrain surface, which will result in incorrectly elevated DTMs. The application of the ranking filter leads to a reduced bias in the DTM height, but a slightly increased noise level.

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Torres, Sebastián M., and Dusan S. Zrnic. "Ground Clutter Canceling with a Regression Filter." Journal of Atmospheric and Oceanic Technology 16, no. 10 (1999): 1364–72. http://dx.doi.org/10.1175/1520-0426(1999)016<1364:gccwar>2.0.co;2.

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Xu, Qianxiang, Mingsheng Liao, Jiansi Yang, and Shoujing Yin. "Distance-limited filter for extracting ground points." Geo-spatial Information Science 12, no. 1 (2009): 46–49. http://dx.doi.org/10.1007/s11806-009-0172-6.

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Sakai, Yasunobu, Tetsuya Uno, Junichi Takagi, and Tsukasa Yamashita. "Optical Spatial Filter Sensor for Ground Speed." Optical Review 2, no. 1 (1995): 65–67. http://dx.doi.org/10.1007/s10043-995-0065-3.

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Efavi, Johnson Kwame, Abu Yaya, Solomon Adeborna, and Julius Fobil. "Development and Comparative Analysis of Aluminosilicate Based Ceramic Filters for Ground Water Defluoridation." Advanced Materials Research 936 (June 2014): 822–28. http://dx.doi.org/10.4028/www.scientific.net/amr.936.822.

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Low levels of fluoride in drinking water is healthy for the teeth enamel, however, higher concentrations result in dental fluorosis with prolonged exposures leading to skeletal fluorosis. Fluoride removal capacities of ceramic filters using aluminosilicates (Anfoega clay, Kibi kaolin, Laterite soil and Termitaria earth) samples from Ghana Geological Survey Department have been investigated and analysed for possible application in the Bongo District of Ghana noted forhavinghigh fluoride concentration in its ground water. Batch sorption studies conducted revealed that the amount of fluoride ions removed increased proportionally with increasing filter thickness, temperature and contact time to an optimum value. Using particle size ranges of <355μm and 1cm filter thickness at room temperature, the percentage of fluoride removed by the samples reached an optimum value after 70mins. Increases in filter thickness, contact time or temperatureincreased the amount of fluoride ions removedand the time required to reach the optimum value reduced significantly.

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Et.al, Kavitha Devi CS. "A Compact Bandpass Microstrip Filter for Wireless Communication Applications." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 6 (2021): 161–65. http://dx.doi.org/10.17762/turcomat.v12i6.1281.

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A design of Compact Bandpass Microstrip Filter is proposed for wireless communication applications like Bluetooth, Wi-Fi, and 5G. Filter is constructed using parallel-coupled Microstrip lines to form 5th order filter of an inverted C structure. Ground slotted technique is used to enhance the bandwidth with dielectric constant of 9.9. The designed filter is simulated at a center frequency of 5.87GHz and bandwidth of 1.9GHz with an insertion loss of -0.5dB, return loss of greater than 12dB. The proposed filter has a compact size, good increased bandwidth and cost-effective. These results are verified with the theoretically designed values and good agreements are recorded. Hence the proposed compact filter will provide a platform for designing and development of compact filters for the microwave regime.

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Farida, Fitri, and Eko Setijadi. "Perancangan Filter Bandpass dengan Teknik Penggabungan Filter Lowpass dan Highpass." Jurnal Sustainable: Jurnal Hasil Penelitian dan Industri Terapan 7, no. 1 (2018): 32–38. http://dx.doi.org/10.31629/sustainable.v7i1.436.

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UWB technology started to become an attraction in the field of research since the Federal Communications Commission (FCC) allowing this communication is used for commercial communications at a frequency (3.1 GHz - 10.6 GHz). UWB has a very wide frequency range so that in practice there is often interference due to signal interference. Therefore in UWB system filter design is required to maintain UWB device. In telecommunications, filter is a transmission device that has the function to pass the desired frequency. In this paper designed bandpass filter which is applied for UWB technology. The designed bandpass filter is a combination of a lowpass filter (LPF) and a highpass filter (HPF). The lowpass filter has the characteristic of passing a frequency lower than its cut-off frequency. The highpass filter has the characteristic passing a frequency higher than its cut-off frequency. Considering the characteristics of both filters, the bandpass filter (BPF) is a combination of lowpass and highpass filters. In this research designed lowpass filter in microstrip technology with step-impedance method, that is by combining high impedance microstrip and low impedance microstrip with a certain length. As for designing HPF using the distribution method of short circuit stubs by adding via ground on each stub. The design of this filter uses Roger substrate RT 5880 with dielectric constant er = 2,2 with thickness (h) = 0.508 mm. In this research it can be concluded that bandpass filter can be designed with lowpass and highpass filter incorporation method, although at the merging of highpass and lowpass structures is disturbed by each other, but overall design shows matching bandpass. Keywords—Microstrip, Lowpass Filter, Highpass Filter, Bandpass Filter.

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Fitria Nurjihan, Shita, and Achmad Munir. "Rancang Bangun Filter Bandpass Mikrostrip Pita Sangat Lebar Berbasis Defected Ground Structure (Design of Ultra Wideband Microstrip Bandpass Filter Based on Defected Ground Structure)." Jurnal Nasional Teknik Elektro dan Teknologi Informasi 9, no. 1 (2020): 104–9. http://dx.doi.org/10.22146/jnteti.v9i1.119.

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Along with the rapid development of technology, many techniques have been employed to improve filter performance by using microstrip, one of them is using a Defected Ground Structure (DGS) technique. The DGS is a technique implemented by combining various forms of slot on the groundplane of filter. This paper presents an ultra wideband (UWB) filter designed using DGS technique by combining two kind of slots on the groundplane, i.e., rectangular slot and rectangular ring slot. The design of composed filter is initialized using filter without DGS, then by adding two kinds of DGS on the groundplane. The DGS is used to improve S-parameter values and increase bandwidth. The method of filter design is using several parametric studies, such as changing the length of patch, width of patch, number of rectangular slot, length of rectangular slot, width of rectangular slot, and gap in rectangular ring slot. This filter is fabricated on a FR4 epoxy dielectric substrate with the thickness of 0.8 mm and the size of 27.4 mm x 22 mm. The measurement result shows that the filter could produce the working bandwidth of 4.01 GHz in the frequency range from 1.52 GHz to 5.53 GHz.

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Lafleche, P. T., J. P. Todoeschuck, O. G. Jensen, and A. S. Judge. "Analysis of ground-probing radar data: predictive deconvolution." Canadian Geotechnical Journal 28, no. 1 (1991): 134–39. http://dx.doi.org/10.1139/t91-014.

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Recent advances in ground-probing radar instrumentation have allowed the collection of large volumes of digital data. Such data sets are amenable to modern data-processing techniques both to increase geological resolution and to enhance data presentation. The close similarity between ground-radar data and seismic data suggests that processing techniques that have been used in the seismic industry could be applied to radar data. As an example, a ground probing radar profile is deconvolved using the common prediction-error filter, which assumes a white power spectrum for the reflections, and a filter that assumes a spectrum proportional to spatial frequency. With the prediction-error filter we find three of four buried pipes which are not visible in the undeconvolved section; all four are found with the second filter. Key words: ground-penetrating radar, deconvolution, scaling geology, frozen-core dams, permafrost, containment dams, mill waste, Contwoyto Lake.

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Hu, Xian Jun, Hang Yu Wang, and Zhang Song Shi. "Ground Target Tracking Using Aerial Images." Advanced Materials Research 734-737 (August 2013): 2964–69. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.2964.

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The tracking of ground targets using aerial images was studied. A improved Kalman filter was derived for the tracking of ground targets. The novel feature of this improved filter were that the grey prediction equations and the road information have been incorporated to improve the accuracy of state estimates.The GM(1,1) (Grey Model) was introduced into Kalman prediction equations.The next value was forecasted by using few forward estimated values with a grey differential equation,which was baesd on the correction of mesurement covariance matrix. The tracking of the targets shows a satisfactory result.

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Hollings, P., M. J. Hendry, and R. Kerrich. "Sequential Filtration of Surface and Ground Waters from the Rabbit Lake Uranium Mine, Northern Saskatchewan, Canada." Water Quality Research Journal 34, no. 2 (1999): 221–48. http://dx.doi.org/10.2166/wqrj.1999.010.

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Abstract Major, trace and rare earth element analyses were conducted on water samples from four sites at the Cameco Rabbit Lake uranium mine in northern Saskatchewan, Canada. Samples were collected from the mill discharge, raise water, the tailings and an adjacent well. Water samples were sequentially filtered through 3.0-µm, 0.45-µm, 0.2-µm, 0.1-µm and 0.02-µm Millipore filters. Trace element and metal abundances were higher in unfiltered samples directly related to the tailings management facility (TMF) than the adjacent ground-water sample. The majority of the metals, including As and Ni, were trapped on the 3.0-µm filter, with the remainder of the metals in all four samples either in solution or transported by extremely small colloidal material (&lt;0.02 µm). Filtration through a 3-µm filter resulted in a substantial decrease in the absolute abundances of the REE in the samples directly associated with the TMF; however further filtration through progressively finer filters did not result in detectable variations in REE abundances. In the TMF-related samples removal of suspended sediment by the 3-µm filter resulted in changes in the REE patterns which were not observed in subsequent filtrations. The well sample did not display major variations in REE abundances with filtration, reflecting the lower colloidal load in that sample. Consequently, filtration through 3.0-µm or 0.45-µm filters will remove the majority of colloidal material at the Rabbit Lake uranium mine.

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Nurjihan, Shita Fitria, and Yenniwarti Rafsyam. "Ultra-Wideband Microstrip Bandpass Filter and Its Equivalent Circuit." IJITEE (International Journal of Information Technology and Electrical Engineering) 5, no. 2 (2021): 52. http://dx.doi.org/10.22146/ijitee.65695.

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Microstrip filters can be designed with various methods to obtain good performances, such as defected ground structure, open-ended slot, planar edge coupled, and split ring resonator with groundplane windowing. In this paper, the design of an ultra-wideband microstrip bandpass filter used the defected ground structure (DGS) method by adding a circular slot to the groundplane. The addition of the circular slot was carried out to improve the value of S parameter (return loss and insertion loss) from the initial filter design without a circular slot. In the simulation process, optimization was carried out by changing the value of filter component parameters such as patch length and thickness and circular slot width. The simulation results showed that the microstrip bandpass filter could pass frequencies in the range of 1.4 GHz to 5.7 GHz with the bandwidth response of 4.3 GHz. In addition, filter analysis could also be done with an equivalent circuit represented by lumped element components in the form of capacitors and inductors connected in series or parallel. The simulation results of the equivalent circuit had a wider bandwidth, which was able to pass frequencies in the range of 1.2 GHz to 6.1 GHz with a bandwidth response of 4.9 GHz.

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MacCarley, C. Arthur, and Erik L. Sandberg. "Traffic Ground Truth Estimation Using Multisensor Consensus Filter." Transportation Research Record: Journal of the Transportation Research Board 2308, no. 1 (2012): 128–37. http://dx.doi.org/10.3141/2308-14.

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Ho, Ka-Meng, Hoi-Kai Pang, and Kam-Weng Tam. "Dual-band bandpass filter using defected ground structure." Microwave and Optical Technology Letters 48, no. 11 (2006): 2259–61. http://dx.doi.org/10.1002/mop.21929.

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Mohan, Akhilesh, and Animesh Biswas. "Dual-band bandpass filter using defected ground structure." Microwave and Optical Technology Letters 51, no. 2 (2008): 475–79. http://dx.doi.org/10.1002/mop.24067.

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Kim, Jeong Phill, and Wee Sang Park. "Microstrip lowpass filter with multislots on ground plane." Electronics Letters 37, no. 25 (2001): 1525. http://dx.doi.org/10.1049/el:20011043.

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Liu, H. W., L. Shen, Y. Jiang, et al. "Triple-mode bandpass filter using defected ground waveguide." Electronics Letters 47, no. 6 (2011): 388. http://dx.doi.org/10.1049/el.2011.0006.

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Kufa, M., and Z. Raida. "Lowpass filter with reduced fractal defected ground structure." Electronics Letters 49, no. 3 (2013): 199–201. http://dx.doi.org/10.1049/el.2012.3473.

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Agrawal, R., K. Margandan, K. Singh, R. Acharya, S. Sharma, and K. Qanungo. "FABRICATION AND TESTING OF INTERMEDIATE LEVEL ACTIVATED ALUMINA BASED DEFLUORIDATION FILTERS." Periódico Tchê Química 10, no. 19 (2013): 65–80. http://dx.doi.org/10.52571/ptq.v10.n19.2013.65_periodico19_pgs_65_80.pdf.

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Two high capacity, high flow rate defluoridation filters with 10 and 25kg Activated Alumina have been fabricated and tested with local fluoride contaminated ground water. Various water quality parameters like pH, TDS, F-, Cl-, SO42-, NO3-, Ca2+ Hardness, Mg2+ Hardness, Total Hardness have been monitored throughout the filtration process and it has been found that these values are within the permissible limits. The filter performance has been evaluated by determining the volume of safe water (1.5 ppm), fluoride uptake capacity, flow rate, empty bed contact time, water capacity of filter, time before first regeneration, capital and recurring cost of filter. On basis of detailed discussion on these parameters the filter with 10 kg AA is considered to be a better filter as compared to the one with 25 kg AA

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Kushwah, Vivek Singh. "CIRCULAR DEFECTED GROUND MICROSTRIP BAND-REJECT FILTER DESIGN FOR RADAR COMMUNICATION." International Journal of Engineering Technologies and Management Research 5, no. 2 (2020): 346–54. http://dx.doi.org/10.29121/ijetmr.v5.i2.2018.666.

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In this paper, a novel narrow band microstrip band-reject filter is designed using three circular shape defected ground structure (DGS). Three circular shape defected ground structure are linked by a path in the ground plane where etching process is applied. The path length of middle DGS cell is 8 mm and the path length of corner DGS cell is 11 mm whereas the path width of all three DGS cell is 0.6 mm and the radius of circular shape defected ground structure is 2.1 mm. The mid-stop band frequency of the designed filter is 1.61 GHz which is applicable for the satellite and radar communication for the purpose of S-Band. The stop bandwidth of proposed filter is 1 GHz to 2.2 GHz which is useful for narrowband communication. The proposed filter has minimum return loss of 0.11 dB and maximum insertion loss of 60 dB at mid stop-band frequency 1.61 GHz. IE3D 14.1 EM simulation tool is applied for finding out the desired outcome. The proposed microstrip band stop filter has a coverage area of (35.1 mm× 14.4 mm) 505.44 mm2 for the top layer and (16.6 mm× 19 mm) 315.4 mm2 for the ground layer which is more compact as compared to other existing band stop filter designs.

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Ural, Serkan, and Jie Shan. "A MIN-CUT BASED FILTER FOR AIRBORNE LIDAR DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 395–401. http://dx.doi.org/10.5194/isprsarchives-xli-b3-395-2016.

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LiDAR (Light Detection and Ranging) is a routinely employed technology as a 3-D data collection technique for topographic mapping. Conventional workflows for analyzing LiDAR data require the ground to be determined prior to extracting other features of interest. Filtering the terrain points is one of the fundamental processes to acquire higher-level information from unstructured LiDAR point data. There are many ground-filtering algorithms in literature, spanning several broad categories regarding their strategies. Most of the earlier algorithms examine only the local characteristics of the points or grids, such as the slope, and elevation discontinuities. Since considering only the local properties restricts the filtering performance due to the complexity of the terrain and the features, some recent methods utilize global properties of the terrain as well. This paper presents a new ground filtering method, Min-cut Based Filtering (MBF), which takes both local and global properties of the points into account. MBF considers ground filtering as a labeling task. First, an energy function is designed on a graph, where LiDAR points are considered as the nodes on the graph that are connected to each other as well as to two auxiliary nodes representing ground and off-ground labels. The graph is constructed such that the data costs are assigned to the edges connecting the points to the auxiliary nodes, and the smoothness costs to the edges between points. Data and smoothness terms of the energy function are formulated using point elevations and approximate ground information. The data term conducts the likelihood of the points being ground or off-ground while the smoothness term enforces spatial coherence between neighboring points. The energy function is optimized by finding the minimum-cut on the graph via the alpha-expansion algorithm. The resulting graph-cut provides the labeling of the point cloud as ground and off-ground points. Evaluation of the proposed method on the ISPRS test dataset for ground filtering demonstrates that the results are comparable with most current existing methods. An overall average filtering accuracy for the 15 ISPRS test areas is 91.3%.

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De Almeida, T., F. Mesléard, M. Santonja, R. Gros, T. Dutoit, and O. Blight. "Above- and below-ground effects of an ecosystem engineer ant in Mediterranean dry grasslands." Proceedings of the Royal Society B: Biological Sciences 287, no. 1935 (2020): 20201840. http://dx.doi.org/10.1098/rspb.2020.1840.

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Within a local assemblage, ecosystem engineers can have major impacts on population dynamics, community composition and ecosystem functions by transforming or creating new habitats. They act as an ecological filter altering community composition through a set of environmental variables. The impact of ants on their environment has been widely studied, but their multi-component effects (both trophic and non-trophic) have been rarely addressed. We investigated the roles of Messor barbarus , one of the commonest harvester ant species in south-western European Mediterranean grasslands. We analysed soil physico-chemical parameters, above-ground vegetation (e.g. species richness, plant community, micro-local heterogeneity, plant biomass) and above- and below-ground fauna (macrofauna, Collembola, Acari and nematodes). A clear and strong local impact of M. barbarus on soil, vegetation and fauna compartments emerges. The environmental filter is altered by modifications to soil physico-chemical properties, and the biotic filter by changes to plant communities and altered above- and below-ground fauna abundance, occurrence and community structure. The engineering activity of M. barbarus affects not only these separate ecosystem components but also the trophic and non-trophic relationships between them. By altering ecological filters at a local scale, M. barbarus creates habitat heterogeneity that may in turn increase ecological niches in these highly diverse ecosystems.

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Lee, Se-Hyeok, and Junho Song. "Regularization-Based Dual Adaptive Kalman Filter for Identification of Sudden Structural Damage Using Sparse Measurements." Applied Sciences 10, no. 3 (2020): 850. http://dx.doi.org/10.3390/app10030850.

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This paper proposes a dual adaptive Kalman filter to identify parameters of a dynamic system that may experience sudden damage by a dynamic excitation such as earthquake ground motion. While various filter techniques have been utilized to estimate system’s states, parameters, input (force), or their combinations, the filter proposed in this paper focuses on tracking parameters that may change suddenly using sparse measurements. First, an advanced state-space model of parameter estimation employing a regularization technique is developed to overcome the lack of information in sparse measurements. To avoid inaccurate or biased estimation by conventional filters that use covariance matrices representing time-invariant artificial noises, this paper proposes a dual adaptive filtering, whose slave filter corrects the covariance of the artificial measurement noises in the master filter at every time-step. Since it is generally impossible to tune the proposed dual filter due to sensitivity with respect to parameters selected to describe artificial noises, particle swarm optimization (PSO) is adopted to facilitate optimal performance. Numerical investigations confirm the validity of the proposed method through comparison with other filters and emphasize the need for a thorough tuning process.

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Werthmüller, Dieter, Kerry Key, and Evert C. Slob. "A tool for designing digital filters for the Hankel and Fourier transforms in potential, diffusive, and wavefield modeling." GEOPHYSICS 84, no. 2 (2019): F47—F56. http://dx.doi.org/10.1190/geo2018-0069.1.

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The open-source code fdesign makes it possible to design digital linear filters for the Hankel and Fourier transforms used in potential, diffusive, and wavefield modeling. Digital filters can be derived for any electromagnetic (EM) method, such as methods in the diffusive limits (direct current, controlled-source EM [CSEM]) as well as methods using higher frequency content (ground-penetrating radar [GPR], acoustic and elastic wavefields). The direct matrix inversion method is used for the derivation of the filter values, and a brute-force minimization search is carried out over the defined spacing and shifting values of the filter basis. Included or user-provided theoretical transform pairs are used for the inversion. Alternatively, one can provide layered subsurface models that will be computed with a precise quadrature method using the EM modeler empymod to generate numerical transform pairs. The comparison of the presented 201 pt filter with previously presented filters indicates that it performs better for some standard CSEM cases. The derivation of a longer 2001 pt filter for a GPR example with a 250 MHz center frequency proves that the filter method works not only for diffusive EM fields but also for wave phenomena. The presented algorithm provides a tool to create problem specific digital filters. Such purpose-built filters can be made shorter and can speed up consecutive potential, diffusive, and wavefield inversions.

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Deighan, Andrew J., and Doyle R. Watts. "Ground‐roll suppression using the wavelet transform." GEOPHYSICS 62, no. 6 (1997): 1896–903. http://dx.doi.org/10.1190/1.1444290.

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Low‐frequency, high‐amplitude ground roll is an old problem in land‐based seismic field records. Current processing techniques aimed at ground‐roll suppression, such as frequency filtering, f-k filtering, and f-k filtering with time‐offset windowing, use the Fourier transform, a technique that assumes that the basic seismic signal is stationary. A new alternative to the Fourier transform is the wavelet transform, which decomposes a function using basis functions that, unlike the Fourier transform, have finite extent in both frequency and time. Application of a filter based on the wavelet transform to land seismic shot records suppresses ground roll in a time‐frequency sense; unlike the Fourier filter, this filter does not assume that the signal is stationary. The wavelet transform technique also allows more effective time‐frequency analysis and filtering than current processing techniques and can be implemented using an algorithm as computationally efficient as the fast Fourier transform. This new filtering technique leads to the improvement of shot records and considerably improves the final stack quality.

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Lee, Jong Ki, and Christopher Jekeli. "Improved Filter Strategies for Precise Geolocation of Unexploded Ordnance using IMU/GPS Integration." Journal of Navigation 62, no. 3 (2009): 365–82. http://dx.doi.org/10.1017/s0373463309005360.

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Efficient and precise geolocation can be achieved by integrating a ranging system, such as GPS, with inertial sensors in order to bridge short outages, enhance accuracy degradation, and increase the temporal resolution in the ranging system. Optimal integration depends on appropriate filter methods that can accommodate the particular short-term dynamics experienced by platforms, such as UXO ground-based detection systems. The traditional extended Kalman filter was designed to integrate data from a linearized system excited by Gaussian noise. We compared this filter to modern filters that obviate these prerequisites, including the unscented Kalman filter, the particle filter, and adaptive variations thereof, using simulated IMU/ranging systems that follow a typical trajectory with both straight and curved segments. The unscented filter performed significantly better than the extended Kalman filter, particularly over the curved segments, yielding up to 50% improvement in the position accuracy using medium-grade inertial measurement units. Similar improvement was obtained for the unscented particle filter, and its adaptive variant, over the unscented Kalman filter (which performed comparably to the extended Kalman filter) when the statistical distribution of the IMU noise was non-symmetric (i.e., essentially non-Gaussian). While the few-centimetre geolocation accuracy goal for highly dynamic UXO characterization applications remains a challenge if tactical grade IMUs are integrated with a significantly degraded ranging system, using filters appropriate to the inherent nonlinear dynamics and potential non-Gaussian nature of the sensor noise tend to reduce overall errors compared to the traditional filter.

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Xing, Zhi Wei, Hui Zhang, and Zhun Ren. "Adaptive Kalman Filter Based Aircraft Ground Icing Thickness Prediction." Advanced Materials Research 562-564 (August 2012): 1660–67. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.1660.

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The nonlinear dynamics model is used to describe the change of aircraft icing thickness and icing deformation accelerations is viewed as dynamic noise in this paper. Then, a dynamic prediction model of aircraft icing thickness is established with the theory of adaptive kalman filter. And the adaptive kalman filter method based aircraft icing thickness prediction model is employed to forecast aircraft ground icing thickness and compared with support vector machine, BP neural network prediction method. The result of the instance simulation and analysis indicates that the adaptive kalman filter method based aircraft icing thickness prediction posed in this paper is reliable, simple and rapid, and the model has high prediction precision which can realize real-time tracking and prediction and has definite value of both theory and practice.

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Torres, Sebastián M., and David A. Warde. "Ground Clutter Mitigation for Weather Radars Using the Autocorrelation Spectral Density." Journal of Atmospheric and Oceanic Technology 31, no. 10 (2014): 2049–66. http://dx.doi.org/10.1175/jtech-d-13-00117.1.

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Abstract Radar returns from the ground, known as ground clutter, can contaminate weather signals, often resulting in severely biased meteorological estimates. If not removed, these contaminants may artificially inflate quantitative precipitation estimates and obscure polarimetric and Doppler signatures of weather. A ground-clutter filter is typically employed to mitigate this contamination and provide less biased meteorological-variable estimates. This paper introduces a novel adaptive filter based on the autocorrelation spectral density, which is capable of mitigating the adverse effects of ground clutter without unnecessarily degrading the quality of the meteorological data. The so-called Clutter Environment Analysis using Adaptive Processing (CLEAN-AP) filter adjusts its suppression characteristics in real time to match dynamic atmospheric environments and meets Next Generation Weather Radar (NEXRAD) clutter-suppression requirements.

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Berka, Mohammed, Zoubir Mahdjoub, and Mourad Hebali. "New design of dual-band bandpass microwave filter based on electromagnetic effect of metamaterial resonators." Journal of Electrical Engineering 69, no. 4 (2018): 311–16. http://dx.doi.org/10.2478/jee-2018-0044.

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Abstract Recent research on microwave filters show that there are constraints in their design; Effective solutions are needed for high-quality systems. In this manuscript, a new design of microwave dual-band bandpass filter is presented. The complementary metamaterial resonators with magnetic activity and negative permeability (µ < 0) are engraved on the lower ground plane and coplanar guides are maintained in the upper plane of the filter. Both (CSRRs) used have different shapes and dimensions from one another to have a dual band-pass behavior of our filter outside the range 5 to 6 GHz to avoid clutter with other microwave transmission systems. The supply lines used for the inlet and the filter outlet has coplanar access. To show the influence of the coupling of the two metamaterials resonators with the coplanar waveguides on the qualities of the filter, we do simulations using HFSS commercial software.

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Deng, Zhong Liang, Chang Shu, and Nai Bo Zhang. "Design of a Dual Stop-Band Filter Based on Coplanar Waveguide." Applied Mechanics and Materials 151 (January 2012): 145–49. http://dx.doi.org/10.4028/www.scientific.net/amm.151.145.

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This letter presents a dual stop-band filer based on coplanar waveguide (CPW), which consists of two spiral-shaped defected ground structure (DGS). The model of the equivalent circuit, discussing the influence of the spiral shape size, and simulated performances are presented. Finally, a dual stop-band filter is presented and verified by simulations, which is operated from 11.5 to 14 GHz and 23 to 28 GHz.

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