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We present relative astrometric and photometric measurements of visual double stars made in 2016–2017, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry and the direct vector autocorrelation (DVA) method. From our observations of 1,510 multiple stars, we obtained 2,918 new measurements with angular separations in the range 0″.1–20″ and an average accuracy of 0.019$$ 0.019 $$. The mean error on the position angles is 1°.1. Most of the position angles were determined without the usual 180° ambiguity with the application of the DVA technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV≈9−12$$ {m}_V\approx 9-12 $$) with large magnitude differences (up to ΔmV≈4.5$$ \Delta {m}_V\approx 4.5 $$). We have thus been able to measure six systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 593 double stars with a mean error of 0.1 mag. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 46 measurements with an angular separation smaller than the diffraction limit of our instrumentation. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. We also report the measurements of 205 new double stars that we found in the files obtained during the observations. [ABSTRACT FROM AUTHOR]

We present relative astrometric and photometric measurements of visual double stars made in 2013–2015, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Most of the observations were done in 2015, but some other observations of wide couples were done in 2013–2014 (0.3% of the total of the observations). Three different techniques were used for obtaining measurements: lucky imaging, speckle interferometry and the direct vector autocorrelation method. From our observations of 2837 multiple stars, we obtained 5182 new measurements with angular separations in the range of 0″$$ {}^{{\prime\prime} } $$.1–32″$$ {}^{{\prime\prime} } $$ and an average accuracy of 0″.018$$ {0}^{{\prime\prime} }.018 $$. The mean error on the position angles is 0°.8. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV≈9−11$$ {m}_V\approx 9-11 $$) with large magnitude difference (up to ΔmV≈4.5$$ \Delta {m}_V\approx 4.5 $$). We have thus been able to measure 21 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 1079 double stars with an estimated error of 0.2 mag. Except for a few objects that are discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 196 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. We also report measurements of the 164 new double stars that we found in the files obtained during the observations. Finally, from a study of the DR3 Gaia release, it is shown that all the objects of the Tycho Double Star Catalog that we did not resolve in 2015 are probably false detections by Tycho. [ABSTRACT FROM AUTHOR]

Four tropical transition (TT) events in the North Atlantic basin are simulated with the Weather Research and Forecasting (WRF) and the HARMONIE‐AROME (HAR) models to study the main features of the horizontal kinetic energy (HKE) spectra of these kinds of high‐energetic atmospheric system. Though most of the times similar results are obtained with both models, HAR shows a more intense filtering and numerical dissipation, whereas WRF tends to represent overenergized spectra in the synoptic scale and especially at smaller wavelengths. Predictability is dissimilar for the four TTs studied due to the different spectral curve slope obtained for each case, ranging from unlimited to very poor predictability at synoptic scale. Additionally, an increased HKE is presented in the middle–upper troposphere spectra. A deep analysis of the different terms involved in the equation of the spectral energy budget is presented through a detailed study of one of these TTs. The role of all of them is studied, connecting the energy spectra and the meteorological processes involved. The energy budget terms related to the nonlinear spectral transfer, the three‐dimensional divergence, and diabatic process tendencies are identified as the key ones, whereas the potential and kinetic conversion terms and the vertical flux HKE and pressure divergence terms play a secondary role on modulating the spectrum behaviour. The major energetic contributions are found at the synoptic scale, but results show that a two‐dimensional energy cascade does not fully capture the whole spectrum of a TT. The role of convection, latent heat release, and moist convection outbursts is sketched and a link within different vertical levels is found. Results show that a high‐energetic system, such as a TT, can effectively alter the atmospheric energy behaviour. [ABSTRACT FROM AUTHOR]

Knowledge of local mechanical behaviour of wood is especially important as silvicultural practices are modified to allow wood to compete as a relevant material in high technology applications. Challenges associated with identification of local mechanical behaviour have resulted in simplified test geometries designed to determine one or two constitutive parameters. The objective of this work was to design and simulate an entire experiment developed to simultaneously identify the earlywood and latewood orthotropic stiffnesses in loblolly pine in a single specimen and load geometry. The virtual experiment was capable of evaluating optimal orthotropy orientation for reduced identification errors and indicating most favourable choices for data smoothing filters and identification methodology. Additionally, certain ring spacing and latewood percentages were shown to produce large errors, but those combinations are unlikely to occur naturally. The simulation was able to identify Q11,Q22, and Q66 with approximately ±10% error; the Q12 error was larger with more scatter. The methodology presented here contributes to the best practices available for heterogeneous stiffness identification. [ABSTRACT FROM AUTHOR]

This paper presents efficient and practical implementations of sequential data assimilation methods for the Simplified Parameterizations, primitive‐Equation DYnamics (SPEEDY) Model, a well‐known numerical model, into the data assimilation community for climate prediction. In the SPEEDY model, the time evolution of dynamics is performed via the second‐order Leapfrog integration scheme; this time integrator relies on two steps: the position and the velocity. The computational implementation of SPEEDY blends the time integrator and the spatial discretization of dynamics to accelerate algebraic computations. Thus, there is no access to the right‐hand side function of the ordinary differential equations governing the time evolution of model dynamics. Consequently, the SPEEDY model is often treated as a black box wherein positions and velocities work as inputs and outputs. Since observations in operational data assimilation only match position states, we can exploit augmented vector states to propagate analysis innovations from positions to velocities. For this purpose, we formulate three variants of ensemble‐based filters and perform numerical experiments to assess their accuracies. We consider two scenarios for the experiments: an ideal case wherein positions and velocities can be observed and a more realistic one wherein measurements are only accessible for position states. Besides, we discuss the effects of the ensemble size on the accuracies of our formulations and, even more, the typical case in which velocities are not updated across assimilation steps. The results reveal that all filter formulations' accuracies remain the same in terms of Root‐Mean‐Square‐Error by neglecting observations from velocities (a realistic scenario) even for cases wherein the number of measurements decreases to 6% of model components. Furthermore, for all discussed filter implementations, the propagation of analysis increments from position to velocities improves up to 100% the performance of filter implementations wherein velocities are not updated, a typical operational scenario. [ABSTRACT FROM AUTHOR]

We present relative astrometric and photometric measurements of visual double stars made in 2013–2014 with PISCO2 installed at the 76‐cm refractor of the Côte d'Azur Observatory in Nice (France). Our observation list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry, and the Direct Vector Autocorrelation method. From our observations of 4,864 multiple stars, we obtained 4,952 new measurements with angular separations in the range 0″.1–14″ and an average accuracy of 0″.015. The mean error on the position angles is 1°.0. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV ≈ 9–11) with large magnitude differences (up to ΔmV ≈ 5). We have thus been able to measure 49 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 318 double stars with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 455 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. Finally, we report 378 measurements of the 296 new double stars that we found in the files obtained during the observations. [ABSTRACT FROM AUTHOR]

For radar target tracking with non‐linear measurements, a sequential linear filtering method is proposed in this study, which includes a linear filter based on the position measurements and a linear sequential filter based on the range rate measurement. The linear radar measurement equation in the sequential filter is estimated based on the position filtering result. Furthermore, the feedback information during tracking is adaptively selected according to the quality of the angle measurements. When tracking the manoeuvring target, the proposed sequential linear filtering with adaptive information feedback is combined with the interacting multiple model (IMM) framework, and the IMM filter based on sequential linear filtering with adaptive model probability selection is proposed. Simulation results demonstrate the effectiveness of the proposed algorithms in non‐manoeuvring and manoeuvring target tracking. Compared with traditional algorithms, the tracking performance is improved by the proposed algorithms in both typical non‐manoeuvring and manoeuvring scenes. [ABSTRACT FROM AUTHOR]

Smoothing process can effectively improve the accuracy of the Global Navigation Satellite System (GNSS) position estimation algorithm. In this study, a Doppler‐aided GNSS position estimation algorithm with a B‐spline smoothing strategy is proposed. B‐spline signal processing is used to smoothen the code measurements with Doppler measurements, which were selected because they are more robust and immune to cycle slips than carrier phase measurements. Next, the mathematical expressions of the smoothing process and position estimation are derived. The smoothing process is based on the structure of a digital filter, which is especially suitable for real‐time applications. The Cramer–Rao lower bound of the proposed algorithm is derived. Moreover, a complete implementation structure of the proposed algorithm is presented. The validity of the proposed algorithm is verified through scenario simulation in terms of static, kinematic, and adverse environments. The advantages of the proposed algorithm are demonstrated by comparison with existing algorithms. [ABSTRACT FROM AUTHOR]

The observer design problem for a class of cell population balance models, describing the time evolution of the cell mass density distribution function and the substrate concentration in a continuous‐stirred tank bioreactor with irregular discrete‐time measurements of the cell mass distribution is considered. The model consists of a partial integro‐differential equation coupled with an ordinary differential equation. Using the theory of impulsive systems sufficient conditions for the input‐to‐state‐stability (ISS) of the observation error in the state‐space L1×ℝ+ with respect to the measurement uncertainty are derived in terms of the maximum time between successive measurements and the ISS gain. In absence of measurement uncertainty the convergence conditions imply exponential stability of the observation error dynamics. Besides these rigorous conditions, application‐oriented tuning guidelines are established. The theoretical results are illustrated with numerical simulations including a comparison with a continuous–discrete extended Kalman filter based on the numerical approximation, showing that a similar accuracy is achieved when using a finite‐dimensional approximation of the proposed impulsive observer scheme with a considerably lower computational effort. [ABSTRACT FROM AUTHOR]

We present relative astrometric and photometric measurements of visual binaries made in 2011–2012, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques have been used for obtaining those measurements: Lucky imaging, speckle interferometry, and the direct vector autocorrelation method. From our observations of 3,136 multiple stars, we obtained 3,568 new measurements with angular separations in the range of 0″.1–10″ and an average accuracy of 0″.016. The mean error on the position angles is 1°.7. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV ≈ 9–11) with large magnitude difference (up to ΔmV ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the magnitude difference of the two components of 326 binaries with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in a good agreement with the ephemerides computed with published orbital elements, even for the binaries closer than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 196 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. We also obtained new measurements of the 15th magnitude multiple system CON37, and discovered a faint new double star in its vicinity. Finally, we report 47 measurements of 28 new binaries found during our observations. [ABSTRACT FROM AUTHOR]

Granular filters are used in hydraulic earthen structures as a natural barrier to protect base soils from erosion under seepage conditions. Their performance is greatly dependent on the pore space connectivity that provides transport pathways for migrating fine particles. Traditional filter design rules are based on characteristic particle diameters of the involved materials, which do not explicitly reflect the pore structure dimensions. Even though the literature offers some mathematical tools that can be used to characterize the opening size of granular filters, the underlying physical fundamentals are still not sufficiently understood. Therefore, this study aims to provide a plausible physical framework for determining the filter opening size by means of numerical simulations using the discrete element method. From the investigation of particle transport processes in polydisperse packings of spheres, the opening sizes associated to these numerical filters are defined on the basis of their constriction size distribution. A mathematical procedure is then introduced to determine the effective opening size of the filter and subsequently, a revised retention criterion for granular filters is proposed and validated with experimental data from the literature. The study findings can offer a valuable perspective for erosion assessment methods in both new and existing earthen structures. [ABSTRACT FROM AUTHOR]

A liquid level sensor system based on dual tapers all‐fiber Mach‐Zehnder interferometer incorporating digital filtering is proposed for extended measurement range. Digital filtering technique is employed to selectively isolate beating of a particular dominant cladding mode, resulting a more consistent response in terms of spectra quality and wavelength shift. Sensing characteristics of cladding modes also are studied theoretically and experimentally. From experiment, continuous measurement of water level is demonstrated over 1016‐mm range with sensitivity of −0.0021 nm/mm and R2 of 0.9972. To our knowledge, this is the highest measurement range and linearity for liquid level sensor based on interferometric sensing system has been reported. The proposed technique can be very useful to enhance sensing performance for various fiber interferometric sensor applications. [ABSTRACT FROM AUTHOR]

Voltage fluctuations caused output variation in the distributed energy system (such as solar, photovoltaic, and wind) produce flickers. The extraction of voltage flicker envelope parameters and accurate calculation of voltage flicker values are important for voltage flicker detection. Traditional digital filters need to be calculated according to the sampling frequency before they can be designed so that the flicker meter can only sample at a fixed frequency. To overcome the shortcomings of digital filters, a new method for measuring flickers is presented in this study. The proposed method uses analytical mode decomposition (AMD) based on spectral correction and a novel constructed mutual convolution window. The voltage flicker envelope can be extracted using an AMD method, which can replace the filter used in traditional methods, it can be analysed to obtain the corrected spectrum, which is based on an improved fast Fourier transform. The proposed method simplifies the voltage flicker detection process and exhibits high detection accuracy, which with lower detection relative error and stronger anti-interference ability. The simulation analysis and experimental results show that this approach can effectively overcome problems associated with voltage flicker measurements, such as single modulation wave frequency change and multi-frequency modulation wave fluctuation. [ABSTRACT FROM AUTHOR]

Summary: This work presents the design of an asynchronous digital finite impulse response (FIR) filter suitable for high‐performance partial response maximum likelihood (PRML) read channel ICs. A high throughput, low latency FIR filter is the basic requirement for the equalization process in read channels. To achieve the enhancement in speed and reduction in latency of the FIR filter, its computational units are deeply pipelined using high‐capacity hybrid (HC‐hybrid) logic pipeline method. The designed FIR filter has been simulated using UMC‐180 nm and UMC‐65 nm technologies. Simulation results show that the asynchronous digital FIR filter can operate up to a throughput of 1.17 Giga items/s in 180 nm and 2.3 Giga items/s in 65 nm technology yet with the latency in the order of ns. [ABSTRACT FROM AUTHOR]

In this study, the Hybrid MAss flux Convection Scheme (HYMACS) is implemented in the ICOsahedral Non‐hydrostatic (ICON) weather prediction model. In contrast to conventional convection parametrization schemes, the convective up‐ and downdraughts are solely treated as subgrid‐scale processes in HYMACS, whereas the environmental subsidence is passed to the grid‐scale dynamics of the hosting model. It is shown that the operational anisotropic divergence damping in ICON distorts the grid‐scale dynamical response on the net mass transport parametrized by HYMACS. Thus, a revised numerical filter configuration is developed which focuses on both the compatibility to local mass sources (sinks) and the effective suppression of numerical modes inherent from the model's triangular grid. Evaluation of Jablonowski–Williamson dynamical core experiments reveal that the combination of an isotropic second‐order divergence damping with a modified version of the fourth‐order divergence damping outperforms against numerical filters based on diffusion. The obtained results are similar to the operational set‐up indicating just a minor effect on the properties of the dynamical core. Moreover, a series of dry mass lifting experiments with the revised numerical filter confirms its compatability with HYMACS. The distortion of the grid‐scale circulation is removed while gravity waves are still retained despite the potentially degenerative effect of the fourth‐order divergence damping. Analyses of kinetic energy spectra confirm the effective suppression of checkerboard noise for a wide range of different situations. The present study may be understood as a base for future applications of HYMACS with a full cloud model in real‐case studies. [ABSTRACT FROM AUTHOR]

Summary: A class of discrete‐time random processes arising in engineering and econometrics applications consists of a linear state‐space model whose parameters are modulated by the state of a finite‐state Markov chain. Typical filtering approaches are collapsing methods, which approximate filtered distributions by mixtures of Gaussians, each Gaussian corresponding to one possibility of the recent history of the Markov chain, and particle methods. This article presents an alternative approach to filtering these processes based on keeping track of the values of the underlying filtered density and its characteristic function on grids. We prove that it has favorable convergence properties under certain assumptions. On the other hand, as a grid method, it suffers from the curse of dimensionality, and so is only suitable for low‐dimensional systems. We compare our method to collapsing filters and a particle filter with examples, and find that it can outperform them on 1‐ and 2‐dimensional problems, but loses its speed advantage on 3‐dimensional systems. Meanwhile, our method has a proven theoretical convergence rate that is probably not achieved by collapsing and particle methods. [ABSTRACT FROM AUTHOR]

Waveform match‐filtering (MF), based on cross‐correlation between an earthquake pair, is a powerful and widely used tool in seismology. However, its performance can be severely affected by several factors, including the length of the cross‐correlation window, the frequency band of the applied digital filter, and the presence of a large‐amplitude phase(s). To optimize the performance of MF, we first systematically examine the effects of different operational parameters and determine the generic rules for selecting the window length and the optimal frequency passband. To minimize the influence of a large‐amplitude phase(s), we then propose a new approach, namely, MF with multisegment cross‐correlation (MFMC). By equally incorporating the contributions from various segments of the waveforms, this new approach is much more sensitive to small separation between two sources compared to the conventional MF method using the entire waveform template. To compare the reliability and effectiveness of both methods in capturing interevent source separation and identifying repeating earthquakes, we systematically conduct experiments with both synthetic data and real observations. The results demonstrate that the conventional MF method can detect the existence of an event but sometimes lacks the resolution to tell whether the template and detected events are co‐located or not, whereas MFMC works in all cases. The far‐reaching implication from this study is that inferring source separation between an earthquake pair based on the conventional MF method, particularly with data from a single channel/station, may not be reliable. Key Points: Selecting a proper template window length and an optimal filter is of great importance in optimizing the match‐filtering methodHigh cross‐correlation coefficients obtained by conventional match‐filtering do not necessarily imply small separation between two eventsMatch‐filtering with multisegment cross‐correlation (MFMC) is much more effective and reliable in discriminating source separations [ABSTRACT FROM AUTHOR]

Summary: Load transient and dynamic voltage scaling (DVS) are commonly seen in the operation of the system processor. These two functions usually encounter large output voltage transient, which is hard to be quickly settled. Charge balance control is one of the prior choices that enables the converter to operate at its optimal charge/discharge slew rate so as to achieve fast transient response. The effectiveness of the optimal performance generally requires precise knowledge of the circuit parameters for charge balance computation. However, parameter drifting due to the manufacturing process may affect the performance, which is hard to implement a power integrated circuit (IC) for wide range applications. Different from the original approaches, this paper proposes an auto‐tuning charge balance control (AT‐CBC) to optimize load transient response and DVS of the buck converter. The auto‐tuning mechanism can save the preknowledge of the output filter and avoid complex calculation in digital control. The function of AT‐CBC is validated by a field‐programmable gate array (FPGA) controlled buck converter. Experimental result shows that the output voltage can be settled within 3 μs for the 750‐mA load step transient. For the 0.3‐V DVS transient, the output voltage can be settled within 4 μs. [ABSTRACT FROM AUTHOR]

Wavelet transform is a versatile time‐frequency analysis technique, which allows localization of useful signals in time or space and separates them from noise. The detector output from any analytical instrument is mathematically equivalent to a digital image. Signals obtained in chemical separations that vary in time (e.g., high‐performance liquid chromatography) or space (e.g., planar chromatography) are amenable to wavelet analysis. This article gives an overview of wavelet analysis, and graphically explains all the relevant concepts. Continuous wavelet transform and discrete wavelet transform concepts are pictorially explained along with their chromatographic applications. An example is shown for qualitative peak overlap detection in a noisy chromatogram using continuous wavelet transform. The concept of signal decomposition, denoising, and then signal reconstruction is graphically discussed for discrete wavelet transform. All the digital filters in chromatographic instruments used today potentially broaden and distort narrow peaks. Finally, a low signal‐to‐noise ratio chromatogram is denoised using the procedure. Significant gains (>tenfold) in signal‐to‐noise ratio are shown with wavelet analysis. Peaks that were not initially visible were recovered with good accuracy. Since discrete wavelet transform denoising analysis applies to any detector used in separation science, researchers should strongly consider using wavelets for their research. [ABSTRACT FROM AUTHOR]

This work proposes the use of bandstop filtering (BSF) as a pretreatment method in the quantitative analysis of glucose from both near‐infrared (NIR) and midinfrared (MIR) spectra. The proposed method is investigated and evaluated against the traditional bandpass filtering (BPF) and implemented with the linear calibration models principal component regression (PCR) and partial least squares regression (PLSR) to predict the glucose from an aqueous mixture consisting of glucose and human serum albumin dissolved in a phosphate buffer solution. The results obtained show that BSF pretreatment achieves better prediction performance than BPF in both the NIR and MIR spectral regions. For detailed analysis, the BPF and BSF were implemented under both the Butterworth and Chebyshev filter configurations in both bands; in the NIR region, the Butterworth BSF combined with the PLSR model provides the best glucose prediction by reducing the root mean square error of prediction (RMSEP) from 100 mg/dL without filtering to 34 mg/dL with a coefficient of determination R2 of.982. In the MIR region, the Chebyshev BSF combined with either PLSR or PCR improves the glucose prediction by reducing the RMSEP by 54% compared with 45% when using BPF and with R2 of.995. In this paper, the use of Bandstop filtering has been investigated against the use of Bandpass filtering to predict glucose from 100 samples of aqueous mixture consist of Glucose, Human Serum Albumin dissolved in a phosphate buffer in the NIR and MIR spectral regions. The experimental results revealed that the proposed model provides better glucose prediction than bandpass filter up to 66% in the NIR spectral region and 55% in the MIR spectral region. [ABSTRACT FROM AUTHOR]

In this article, the design, construction and characterization of band‐pass filters (BPF), based on the classic single‐structure, square‐loop, dual‐mode resonator rings (SL‐DMRR) is revisited. A specific requirement is proposed for using such a basic topology: the design and fabrication of L‐band SL‐DMRR filters to be part of the intermediate frequency (IF) section of a heterodyne K‐band microwave transceiver. The heterodyne K‐band transceiver has been designed and implemented to measure atmospheric attenuation at 22.4 GHz, in the vicinity of the strong absorption peak by water vapor molecules in the atmosphere. The BPFs are designed to operate at a center frequency of 1.1 GHz and a minimum bandwidth of 200 MHz. SL‐DMRR filters in the L‐band microwave range are more compact when compared to other microstrip structures such as parallel coupled lines, tapped input digital filters, hairpin filters, and so on. Filter realizations on FR4 and RT/Duroid 6010 substrates are optimized by resolving narrow coupling gap (0.07‐0.1 mm), between the input/output stubs and the resonator ring. Narrow gaps (less than 0.1 mm) are an original achievement in our work to ensure insertion losses of 1 dB for FR4, 0.5 dB for RT/Duroid, return losses better than 20 dB and a minimum bandwidth of 200 MHz. These figures represent an appreciable advancement of the state‐of‐the‐art for these classic structures for filters. The simulated and measured electrical responses of the filters show an excellent agreement. The IF filter has been incorporated to the K‐band receiver and the system's performance is also reported in this article. [ABSTRACT FROM AUTHOR]

A digital filter is introduced which treats the problem of predictability versus time averaging in a continuous, seamless manner. This seamless filter (SF) is characterized by a unique smoothing rule that determines the strength of smoothing in dependence on lead time. The rule needs to be specified beforehand, either by expert knowledge or by user demand. As a result, skill curves are obtained that allow a predictability assessment across a whole range of time‐scales, from daily to seasonal, in a uniform manner. The SF is applied to downscaled SEAS5 ensemble forecasts for two focus regions in or near the tropical belt, the river basins of the Karun in Iran and the São Francisco in Brazil. Both are characterized by strong seasonality and semi‐aridity, so that predictability across various time‐scales is in high demand. Among other things, it is found that from the start of the water year (autumn), areal precipitation is predictable with good skill for the Karun basin two and a half months ahead; for the São Francisco it is only one month, longer‐term prediction skill is just above the critical level. [ABSTRACT FROM AUTHOR]

In this study, the event-triggered distributed fault detection problem is investigated for a class of discrete-time uncertain systems in the finite frequency domain. A sensor network is utilised to collect the information of interest, and an eventtriggered communication scheme is adopted to alleviate the communication burden. For the addressed problem, a distributed fault detection filter is designed based on the measurement information from its neighbouring nodes and itself by the given topology. In addition, a fashionable index, named as H-/H∞ performance, is employed in order to simultaneously achieve the residual sensitivity to faults and the robustness against disturbances. By resorting to Euler's formula combined with Lyapunov stability theory, some sufficient conditions are established to satisfy the desired performance over a given finite-frequency domain, and the distributed fault detection filter gains are explicitly characterised by solving a series of linear matrix inequalities. A simulation example is conducted to illustrate the feasibility of the proposed filter design technique. [ABSTRACT FROM AUTHOR]

Summary: A low power and high‐performance digital electrocardiogram (ECG) detector has become a basic requirement in modern implantable cardiac pacemakers. A fractional operator‐based digital ECG detector for modern pacemaker systems is proposed in this work. Instead of conventional thresholding, an adaptive slope prediction threshold is utilized for the detection of ECG peaks. A stochastic search‐based algorithm, namely, cuckoo search algorithm, is used to design an optimal fractional operator that is used for ECG denoising. It has been found that the proposed adaptive slope prediction threshold increases the QRS complex detection performance. A low detection error rate (DER) ranges from 0.01% to 0.56%, positive predictivity (P+) ranges from 99.32% to 99.98%, sensitivity (Se) ranges from 99.45% to 99.98%, and a detection accuracy (Acc) ranges from 99.43% to 99.96% for different databases are achieved for the proposed ECG detector, which is better compared with the existing ECG detectors. The proposed design of fractional order operator based on the lattice wave digital filter (LWDF) requires a minimum number of the multipliers for its structural realization. [ABSTRACT FROM AUTHOR]

The traditional way to enhance signal‐to‐noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post‐acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD‐NMR) relaxation measurements. The procedures were studied using continuous wave free precession (CWFP‐T1) signals, acquired with very low flip angles that contain six times more noise than the Carr–Purcell–Meiboom–Gill (CPMG) signal of the same sample and experimental time. Linear (LI) and logarithmic (LO) data compression, low‐pass infinity impulse response (LP), Savitzky–Golay (SG), and wavelet transform (WA) post‐acquisition filters enhanced the SNR of the CWFP‐T1 signals by at least six times. The best filters were LO, SG, and WA that have high enhancement in SNR without significant distortions in the ILT relaxation distribution data. Therefore, it was demonstrated that these post‐acquisition digital filters could be a useful way to denoise CWFP‐T1, as well as CPMG noisy signals, and consequently reducing the experimental time. It was also demonstrated that filtered CWFP‐T1 method has the potential to be a rapid and nondestructive method to measure fat content in beef and certainly in other meat samples. [ABSTRACT FROM AUTHOR]

Fundamental phasor estimation is one of the most important jobs to be done by the digital protective relay (DPR). However, fault signals given to DPR consist of decaying DC (DDC) components, harmonics, and noise which can lead to inaccuracy in phasor estimation. Hence, for accurate results, digital filtering algorithms (DFAs) are mandatory to wipe out all these unwanted components. In modern DPR, discrete Fourier transform (DFT) is extensively used DFA for fundamental phasor estimation. However, the accuracy of DFT is affected by the presence of DDC. Hence, to tackle this problem, a new real-time fast DFA based on the mathematical morphology (MM) technique is put forward. First, the DDC components are filtered out using the morphological median filter (MMF) and are subtracted from the original fault signal. Afterwards, the fundamental phasor is extracted from the residual DDC-free signal using the DFT. Several computer-simulated, EMTP-generated, and realfield fault signals are used to examine the efficacy of the proposed DFA. In addition, the proposed DFA is compared with other existing techniques. The obtained results prove that the suggested DFA has vigorous performance in the presence of multiple DDC components, noise, and severe harmonic conditions with a low computational burden and high accuracy. [ABSTRACT FROM AUTHOR]

Since 1 July 2018, the GRAPES (Global/Regional Assimilation and PrEdiction System) global 4‐dimensional variational (4D‐Var) data assimilation system has been in operation at the China Meteorological Administration (CMA). In this study, the GRAPES global 4D‐Var data assimilation system is comprehensively introduced. This system applies the non‐hydrostatic global tangent‐linear model (TLM) and the adjoint model (ADM) for the first time. The use of a digital filter as a weak constraint is achieved. A series of linear physical processes is developed, including vertical diffusion, subgrid‐scale orographic parametrization, large‐scale condensation, and cumulus convection parametrization. The vertical diffusion and subgrid‐scale orographic schemes are used in the operational suite and the linear convection parametrization and large‐scale condensation scheme remain under assessment. The Lanczos and conjugate gradient (Lanczos‐CG) algorithm and the limited‐memory Broyden‐Fletcher‐Goldfarb‐Shanno (L‐BFGS) algorithm are also developed. In terms of computational optimization, the total computational time of the GRAPES global TLM and ADM is approximately threefold that of the GRAPES global nonlinear model (NLM). Before it became operational, a one‐year retrospective trial was performed on the GRAPES global 4D‐Var data assimilation system. The entire system was stable, and the analysis and forecasting performances were significantly better than those of the 3D‐Var data assimilation system, especially in the Southern Hemisphere. [ABSTRACT FROM AUTHOR]

Although Rossby modes of the nonlinear shallow‐water system on the rotating sphere are suspected to be close to their counterpart for the non‐divergent barotropic vorticity equation, little is known about their properties. A numerical procedure is employed to approximate some of these modes for which an analytical expression is known in the non‐divergent case. For stationary modes, the procedure simply consists in iteratively applying a time filter in a forecast initialised with the non‐divergent mode. For zonally propagating modes, a change of frame allows a similar method to be used with only very minor changes to the forecast model. For stable modes, the structure may be approached with high precision by extending the length of the time filter used in the numerical procedure. The structure of the wind divergence field of Rossby modes is then revealed. The modes identified by this mean undergo instabilities of a similar nature to those for the barotropic vorticity equation system. The stability domain and growth rates are explored. Some avenues for improving test cases based on Rossby modes for shallow‐water systems are finally discussed. [ABSTRACT FROM AUTHOR]

Summary: A noniterative method for the all‐pass–based design of infinite impulse response multiple‐notch filters is proposed. This method ensures that specifications regarding positions of notch, left‐ and right‐hand cutoff frequencies, are exactly met, leading to a symmetric magnitude response about notch frequencies. Passband magnitude response can be improved by increasing the order of the corresponding all‐pass filter. A noniterative method for the all‐pass–based design of infinite impulse response (IIR) multiple‐notch filters is proposed. This method ensures that specifications regarding positions of notch, left‐ and right‐hand cutoff frequencies, are exactly met, leading to a symmetric magnitude response about notch frequencies. Passband magnitude response can be improved by increasing the order of the corresponding all‐pass filter. [ABSTRACT FROM AUTHOR]

Recently, physical layer authentication techniques are emerging to detect spoofing attacks in wireless networks based on high consistency between two legitimate successive channel information. However, this high consistency is not always available, especially in dynamic networks, such as mobile scenarios. In this study, the authors propose a physical layer spoofing detection scheme based on sparse signal processing that exploit sparse representation and Savitzky-Golay filter, and use machine learning strategy to improve the spoofing detection accuracy under the case of low channel consistency. Simulation results show that the proposed technique can significantly improve the detection accuracy under the condition of low channel consistency. [ABSTRACT FROM AUTHOR]

Purpose: This study investigates forced localization of targets in simulated images with statistical properties similar to trans‐axial sections of x‐ray computed tomography (CT) volumes. A total of 24 imaging conditions are considered, comprising two target sizes, three levels of background variability, and four levels of frequency apodization. The goal of the study is to better understand how human observers perform forced‐localization tasks in images with CT‐like statistical properties. Methods: The transfer properties of CT systems are modeled by a shift‐invariant transfer function in addition to apodization filters that modulate high spatial frequencies. The images contain noise that is the combination of a ramp‐spectrum component, simulating the effect of acquisition noise in CT, and a power‐law component, simulating the effect of normal anatomy in the background, which are modulated by the apodization filter as well. Observer performance is characterized using two psychophysical techniques: efficiency analysis and classification image analysis. Observer efficiency quantifies how much diagnostic information is being used by observers to perform a task, and classification images show how that information is being accessed in the form of a perceptual filter. Results: Psychophysical studies from five subjects form the basis of the results. Observer efficiency ranges from 29% to 77% across the different conditions. The lowest efficiency is observed in conditions with uniform backgrounds, where significant effects of apodization are found. The classification images, estimated using smoothing windows, suggest that human observers use center‐surround filters to perform the task, and these are subjected to a number of subsequent analyses. When implemented as a scanning linear filter, the classification images appear to capture most of the observer variability in efficiency (r2 = 0.86). The frequency spectra of the classification images show that frequency weights generally appear bandpass in nature, with peak frequency and bandwidth that vary with statistical properties of the images. Conclusions: In these experiments, the classification images appear to capture important features of human‐observer performance. Frequency apodization only appears to have a significant effect on performance in the absence of anatomical variability, where the observers appear to underweight low spatial frequencies that have relatively little noise. Frequency weights derived from the classification images generally have a bandpass structure, with adaptation to different conditions seen in the peak frequency and bandwidth. The classification image spectra show relatively modest changes in response to different levels of apodization, with some evidence that observers are attempting to rebalance the apodized spectrum presented to them. [ABSTRACT FROM AUTHOR]

A novel and efficient method is presented for ground moving target detection. Radar echo data is transformed from element space to beam space using spatial Discrete Fourier Transform (DFT). A motion compensation matrix is applied to the beam-space radar data to compensate for the moving platform effects on the Doppler spectrum. The Doppler-compensated clutter is then eliminated using digital filters in time domain. It is demonstrated by the simulation results that the performance of the proposed airborne moving target indication (AMTI) algorithm is comparable to that of the conventional MTI processing approaches used in the surface-based radar with stationary platform. [ABSTRACT FROM AUTHOR]

Recently, we discussed the concept of direct synthesis technique (DST), in which real-coefficient filtering polynomials containing all information of the filters to be synthesized are derived directly for realization, and they could find applications in the design of lumped-element LC filters, active RC filters, and infinite impulse response digital filters. In this paper, another DST for complex general Chebyshev bandpass filters is discussed, which is based on a complex mapping relation and featured by complex-coefficient filtering polynomials. It is called as complex DST in this paper. Compared with real-coefficient filtering polynomials whose polarities are determined by the number of their zeros at zero frequency, the polarities of complex-coefficient filtering polynomials can be easily changed by multiplying imaginary unit j. Such advantage might make their realization more flexible. The analysis shows that conventional coupling matrix could be considered as narrow-band approximation of network matrix derived by complex DST in the normalized frequency domain. In order to demonstrate the validity of complex DST in this paper, it is applied in the design of classic parallel-coupled microstrip bandpass filters. Compared with conventional synthesis techniques, complex DST could find out better dimensions and provide more choices for realization and synthesize both even-order and odd-order parallel-coupled microstrip bandpass filters. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to design and implement minimum multiplier, low latency structures of a comb filter. Multipliers are the most area and power consuming elements; therefore, it is desirable to realize a filter with minimum number of multipliers. In this paper, design of comb filters based on lattice wave digital filters (LWDF) structure is proposed to minimize the number of multipliers. The fundamental processing unit employed in LWDF requires only one multiplier. These lattice wave digital comb filters (LWDCFs) are realized using Richards' and transformed first-order and second-order all-pass sections. The resulting structural realizations of LWDCFs exhibit properties such as low coefficient sensitivity, high dynamic range, high overflow level, and low round-off noise. Multiplier coefficients of the proposed structures are implemented with canonic signed digit code (CSDC) technique using shift and add operations leading to multiplierless implementation. This contributes in reduction of number of addition levels which reduces the latency of the critical loop. A field programmable gate array (FPGA) platform is used for evaluation and testing of the proposed LWDCFs to acquire advantages of the parallelism, low cost, and low power consumption. The implementation of the proposed LWDCFs is accomplished on Xilinx Spartan-6 and Virtex-6 FPGA devices. By means of examples, it is shown that the implementations of the proposed LWDCFs attain high maximum sampling frequency, reduced hardware, and low power dissipation compared with the existing comb filter structures. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this article, an observer for linear time variant systems affected by unknown inputs is suggested. The proposed observer combines the deterministic least squares filter and the high-order sliding-mode differentiator to provide exact state reconstruction in spite of bounded unknown inputs and system instability. The cascade structure of the algorithm provides a correct state reconstruction for the class of linear time variant systems that satisfy the structural property of strong observability. Simulations illustrate the performance of the proposed algorithm. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Pupose In clinical computed tomography ( CT), the image data is acquired during continuous rotation. If the time during which the signal is integrated (the frame time) is too long, the data is blurred in the view direction (i.e., azimuthal blur). This can be overcome by having a high angular sampling rate, but for systems with limited bandwidth, the increased amount of data can be a problem. In this paper, we evaluate the benefit of maintaining a high angular sampling rate on the CT gantry and performing a decimation (digital low-pass filtration followed by a downsampling) in the view direction before the bottleneck of the data transfer chain. Methods A theoretical evaluation of the effects of the decimation is presented and the implementation of the digital filter is discussed. The compression scheme is evaluated on image data of a CATPHAN [ABSTRACT FROM AUTHOR]

This paper is concerned with the filtering problem for discrete-time networked systems with communication constraints, fading measurements, and multiplicative noises. The communication constraint is that, at each sampling instant, at most one of the various transmission nodes in the networked systems is permitted to access a shared communication channel, and then the received data are transmitted to a remote filter to perform the filtering task. The phenomenon of measurement fading appears in a random way when measurements are transmitted via the communication channel that undergoes slow fading. Using the innovation analysis approach and some results developed in this study, an optimal linear filter is proposed. The proposed optimal filter has a recursive structure and does not increase computation and storage load with time. Computer simulations are conducted to examine the performance of the proposed optimal filter. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT The automatic detection of geological features such as faults and channels is a challenging problem in today's seismic exploration industry. Edge detection filters are generally applied to locate features. It is desirable to reduce noise in the data before edge detection. The application of smoothing or low-pass filters results in noise suppression, but this causes edge blurring as well. Edge-preserving smoothing is a technique that results in simultaneous edge preservation and noise suppression. Until now, edge-preserving smoothing has been carried out on rectangular sampled seismic data. In this paper, an attempt has been made to detect edges by applying edge-preserving smoothing as a pre-processing step in the hexagonally sampled seismic-data spatial domain. A hexagonal approach is an efficient method of sampling and has greater symmetry than a rectangular approach. Here, spiral architecture has been employed to handle the hexagonally sampled seismic data. A comparison of edge-preserving smoothing on both rectangular and hexagonally sampled seismic data is carried out. The data used were provided by Saudi Aramco. It is shown that hexagonal processing results in well-defined edges with fewer computations. [ABSTRACT FROM AUTHOR]

This paper presents a comparison between algorithms (Oriented FAST and Rotated BRIEF (ORB) and Aruco) for the detection of fiducial markers placed throughout a smart environment. A series of activities of daily living (ADL) were conducted while monitoring a first-person perspective of the situation; this was achieved through the usage of the Google Glass platform. Fiducial markers were employed, as a means to assist with the detection of specific objects of interest, within the environment. Each marker was assigned unique Identification (ID) and was used to identify the object. Three activities were performed by a participant within the environment. On subsequent trials of the solution, lighting conditions were modified to assess fiducial marker detection rates on a frame-by-frame basis. This paper presents the results from this investigation, detailing performance measure for each object detected under various lighting conditions, motion blur and distance from the objects. An intelligent system was developed to specifically consider distance estimation in order to aid with the filtering out of false interactions. A linear filtering method was applied along with a fuzzy membership function to estimate the degree of user interaction, which assists in removing false positives generated by the occupant. The intelligent system returns an average precision, recall and an F-Measure of 0.99, 0.62 and 0.49, respectively. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents an online recorded data-based design of composite adaptive dynamic surface control for a class of uncertain parameter strict-feedback nonlinear systems, where both tracking errors and prediction errors are applied to update parametric estimates. Differing from the traditional composite adaptation that utilizes identification models and linear filters to generate filtered modeling errors as prediction errors, the proposed composite adaptation integrates closed-loop tracking error equations in a moving time window to generate modified modeling errors as prediction errors. The time-interval integral operation takes full advantage of online recorded data to improve parameter convergence such that the application of both identification models and linear filters is not necessary. Semiglobal practical asymptotic stability of the closed-loop system is rigorously established by the time-scales separation and Lyapunov synthesis. The major contribution of this study is that composite adaptation based on online recorded data is achieved at the presence of mismatched uncertainties. Simulation results have been provided to verify the effectiveness and superiority of this approach. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Recently, direct synthesis techniques (DSTs) have been presented for filter synthesis. Unlike conventional synthesis techniques, DSTs derive the filtering polynomials of the filters to be synthesized directly in their own frequency domain. These filtering polynomials are real coefficient so that they might find applications in various fields. Furthermore, DSTs might be used to customize filters with a more complex frequency response, such as asymmetric frequency response or multi-band frequency response. In this paper, DSTs are compared with some well-known filter synthesis techniques. Then, the application of DSTs in the design of lumped-element LC filters, distributed-element filters, active RC filters, and infinite impulse response digital filters with complex frequency response is discussed. Some examples are presented for demonstration. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This Letter deals with a practical signal processing problem where the filter is zero-phase and is specified by the frequency response. The authors show that if the signal is symmetrically extended, then the fast Fourier transform (FFT)-based algorithm can be efficiently implemented by using the discrete cosine transform without signal extension. They extend the proposed algorithm to 2D filters and show that computationally it is at least four times more efficient than the FFT-based algorithm. A practical application of the new algorithm is a fast Wiener inverse filter, which is used to estimate images taken under the condition of air turbulence. [ABSTRACT FROM AUTHOR]

A recursive smoothing filter employing a bank of fading-memory polynomial sub-filters is presented. Variance estimates are used to mix the outputs of the sub-filters, imparting variable gain and phase characteristics that permit it to automatically adapt to signal parameter changes. The proposed adaptive technique does not involve the estimation of plant parameters; therefore, it may be used in both open-loop and closed-loop configurations. In open-loop estimation problems, variable gain/bandwidth allows it to reduce the impact of random errors caused by sensor noise and the impact of bias errors caused by model mismatch during 'maneuvers'. In feedback control problems, variable phase/delay allows it to act as a lag filter for an improved steady-state response (i.e. greater noise attenuation) and act as a lead filter, or a proportional-derivative controller, for an improved transient response (i.e. increased closed-loop damping) for input discontinuities. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes a novel method for designing linear-phase finite-impulse response digital filters with an asymmetric transition band. The proposed filters use a form of piecewise exponential functions in the frequency domain where transition characteristics are determined by giving only two fixed feature points. The design method was evaluated in two ways. First, we evaluated a designed asymmetric transition band filter, and the results revealed that evaluated errors in the proposed filters were equivalent to well-known existing filters. Then, it was shown that a three-channel filter bank with an asymmetric transition band and linear-phase property could be implemented. [ABSTRACT FROM AUTHOR]

The transient response of the digital filter for relaying purposes has been improved by means of the Taylor-Kalman-Fourier (TKF) filter. This filter is focused on a dynamic phasor, which is adapted to the transient operating conditions and is based on a signal model that is approximated by the Kth Taylor polynomial. This model is extended to the Kalman and Fourier subspaces in order to provide instantaneous estimates through its recursive property. The TKF renders instantaneous phasor estimates at each sample and enhances the impedance estimation under fault conditions. This fact and the results demonstrate the applicability of the proposition for distance relays. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a digital filter for the generation/correlation of binary Golay pairs of sequences of length 2 N · 10 M · 26 P ( N, M and P are non-negative integers) is proposed. It is carried out by means of a novel Golay kernel 26 decomposition, also introduced in this paper, combined with building blocks of Golay kernels 2 and 10, presented in previous works. The proposed filter has a similar architecture to the digital filter for the generation/correlation of Golay multilevel pairs of sequences, where the parameters at intermediate stages have to be adjusted to obtain Golay binary pairs of sequences in the final stage. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper deals with the similitude between the behaviours of linear filter gain and negative group delay (NGD) function. The transposition method of low-pass/high-pass, low-pass/band-pass and low-pass/band-stop NGD circuits is established. To the best of the author knowledge, it acts as the first paper devoted on the NGD function generalized theory. The introduced transform relationships simplify the synthesis of any NGD circuits from simple elementary low-pass NGD topologies. Families of innovative NGD topologies are identified. To verify the relevance of the concept proposed, frequency- and time-domain analysis results from realistic proofs of concept demonstrating the feasibility of developed NGD transforms were performed. Thanks to the NGD phenomenon, the possibility of the ultra-wideband pulse signals propagating in time-advance is verified. Finally, potential applications of NGD circuits are discussed. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Continuous deflection devices (CDDs) can safely measure pavement deflection (or other related properties) while traveling at highway speed, which reduces traffic disruption. CDD measurements are contaminated with relatively high noise levels compared to stop-and-go devices such as the Falling Weight Deflectometer. In this article, we use wavelet transform denoising to remove the noise and estimate the true deflection slope measurements obtained from the Traffic Speed Deflectometer. Results show that failure to denoise deflection slope measurements can lead to calculated Effective Structural Number values that are highly variable (unstable). Attempting to filter these highly variable measurements can lead to erroneous results. We also use wavelet transform denoising to identify localized weak spots such as those that are caused by pavement reflection cracking. Identifying weak spots with wavelets is possible because wavelets are spatially adaptive to local features. In contrast, a linear filter is not capable of adapting to local features. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, we propose a new design method for linear phase finite impulse response (FIR) filters with discrete coefficients. In a hardware implementation, filter coefficients must be represented as discrete values. The design problem of digital filters with discrete coefficients is formulated as an integer programming problem. But an enormous amount of computational time is required to solve the problem in a strict solver. Recently, ant colony optimization (ACO), a heuristic approach, has been used widely for solving combinational problems such as the traveling salesman problem. In our method, we formulate the design problem as a 0-1 integer programming problem and solve it by using ACO. Several design examples are presented to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]