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BACKGROUND: The polychromatic X-rays generated by a linear accelerator (Linac) often result in noticeable hardening artifacts in images, posing a significant challenge to accurate defect identification. To address this issue, a simple yet effective approach is to introduce filters at the radiation source outlet. However, current methods are often empirical, lacking scientifically sound metrics. OBJECTIVE: This study introduces an innovative filter design method that optimizes filter performance by balancing the impact of ray intensity and energy on image quality. MATERIALS AND METHODS: Firstly, different spectra under various materials and thicknesses of filters were obtained using GEometry ANd Tracking (Geant4) simulation. Subsequently, these spectra and their corresponding incident photon counts were used as input sources to generate different reconstructed images. By comprehensively comparing the intensity differences and noise in images of defective and non-defective regions, along with considering hardening indicators, the optimal filter was determined. RESULTS: The optimized filter was applied to a Linac-based X-ray computed tomography (CT) detection system designed for identifying defects in graphite materials within high-temperature gas-cooled reactor (HTR), with defect dimensions of 2 mm. After adding the filter, the hardening effect reduced by 22%, and the Defect Contrast Index (DCI) reached 3.226. CONCLUSION: The filter designed based on the parameters of Average Difference (AD) and Defect Contrast Index (DCI) can effectively improve the quality of defect images. [ABSTRACT FROM AUTHOR]

In recent decades, there have been individual cases of damage to the revetments of the German North Sea estuaries due to clogging by precipitated ochre products. This process is defined as ochre clogging and has been extensively explained in the literature. The primary aim of the investigations was to better understand the clogging process under in situ conditions and the causative environmental conditions surrounding the filters. Extensive in situ investigations were therefore carried out. It was found that a permeability reduction in geotextile filters can be strongly accelerated by ochre clogging, which appears to be a biogeochemical process. This describes a combined action of the chemical precipitation of iron and manganese, precipitation by microorganisms, and physical clogging. A further aim of this study was to establish limit values for the decisive ochre clogging parameters, which could be used to quantify the susceptibility to ochre clogging. It was shown that the determination of the iron and manganese content of the groundwater, as well as the redox capacity of the groundwater, is sufficient to assess the tendency for ochre clogging. To minimise the negative impact on filter performance, recommendations for an adapted filter design have been developed as a guide for planners. [ABSTRACT FROM AUTHOR]

Providing the population with high-quality drinking water is one of the main state tasks. Rural water supply systems and water supply systems of small settlements in the region require special attention, namely, the development of technologies for individual, small-sized water treatment equipment, as well as equipment for collective use, designed to purify groundwater for drinking purposes. In many areas, there are groundwaters containing excess levels of several pollutants, which makes their purification much more difficult. Elimination of shortcomings in the known methods of water iron removal is possible by reconstructing existing water supply systems from underground sources in small settlements. A rational solution is to search for groundwater treatment technologies that make it possible to provide the population with high-quality drinking water at a lower cost. The result of increasing the concentration of oxygen in water was obtained in the process of modifying the filter by changing the excess air exhaust system, which was made in the form of a perforated pipeline located in the lower half of the granular filter layer connected to the upper branch pipe. At the same time, high-quality groundwater treatment, sufficient simplicity and reliability in operation are ensured, local conditions and the inaccessibility of many objects and settlements in the region are taken into account as much as possible. After the filter was upgraded, the concentration of iron decreased from 4.4 to 0.27 mg/L and ammonium nitrogen from 3.5 to 1.5 mg/L. [ABSTRACT FROM AUTHOR]

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Humans spend a significant portion of their time in the state of sleep, and therefore one's'sleep health' is an important indicator of the overall health of an individual. Non‐invasive methods such as electroencephalography (EEG) are used to evaluate the 'sleep health' as well as associated disorders such as nocturnal front lobe epilepsy, insomnia, and narcolepsy. A long‐duration and repetitive activity, known as a cyclic alternating pattern (CAP), is observed in the EEG waveforms which reflect the cortical electrical activity during non‐rapid eye movement (NREM) sleep. The CAP sequences involve various, continuing periods of phasic activation (phase‐A) and deactivation (phase‐B). The manual analysis of these signals performed by clinicians are prone to errors, and may lead to the wrong diagnosis. Hence, automated systems that can classify the two phases (viz. Phase A and Phase B accurately can eliminate any human involvement in the diagnosis. The pivotal aim of this study is to evaluate the usefulness of stopband energy minimized biorthogonal wavelet filter bank (BOWFB) based entropy features in the identification of CAP phases. We have employed entropy features obtained from six wavelet subbands of EEG signals to develop a machine learning (ML) based model using various supervised ML algorithms. The proposed model by us yielded an average classification accuracy of 74.40% with 10% hold‐out validation with the balanced dataset, and maximum accuracy of 87.83% with the unbalanced dataset using ensemble bagged tree classifier. The developed expert system can assist the medical practitioners to assess the person's cerebral activity and quality of sleep accurately. [ABSTRACT FROM AUTHOR]

A novel wideband multiplexer is introduced as a communications equipment solution in order to provide simultaneous operation of satellite and terrestrial services in the dedicated $K$/$Ka$ frequency bands (passbands ranging from 19.5 GHz to 30.5 GHz). Advanced RF filtering techniques are applied in order to accommodate a compact multiplexer design while maintaining low insertion loss and high rejection demands up to 33 GHz. Due to the overall wide bandwidth and the demanding requirements for the assigned three operational bands, different filter types have been employed. Thus, the multiplexer considers the combination of filters with rectangular, evanescent combline, and conductor-loaded resonator types. The multiplexer relies on the direct branching approach, i.e., all filters are connected to a central (star-junction) waveguide branching region. This region exhibits a reduced waveguide size to suppress interference by higher order modes. For a verification of the approach, WR34 waveguide interfaces have been considered at all ports for prototype design, however, the design can be well adapted for integrated equipment solutions with associated direct interfaces. Accurate coincidence of analyzed and measured performance of the prototype demonstrates the validity of the special approach. Moreover, additional simulations are provided as an outline for terminals with specific industry demands.

In recent years, non-characteristic harmonic resonance was observed in several high-voltage direct current (HVDC) systems in China. Intuitively, additional filters can be installed to mitigate the resonance. However, such a solution does not prevent the harmonic penetration from nearby substations. As a result, the harmonic issue in HVDC systems cannot be well addressed. In view of the above, this paper presents a system-level harmonic mitigation method. The basic idea is to address the harmonic pollution by mitigating harmonic sources and harmonic resonance simultaneously. To achieve this goal, candidates of filters to suppress the resonance at the HVDC station are investigated first. Then, an optimal filter design problem is established to determine the location, type and capacity of multiple filters that can achieve the system-level harmonic mitigation with the minimum cost. Particularly, an improved particle swarm algorithm with adaptive mutation operators is tailor-designed to solve the proposed optimization problem. Finally, the proposed method is applied to address the harmonic problem faced by a real-life HVDC system in eastern China. The result demonstrates that compared with the solutions solely mitigating harmonic sources or resonance, the method presented in this paper is more cost-effectiveness.

This paper discusses the issues of assessing the influence of external distortion sources on the functioning of a shunt passive harmonic filter. In this study, we evaluated the overload of a passive harmonic filter based on determining the contributions of distortion sources. A method was proposed for assessing the contributions of distortion sources, which allowed us, regardless of background distortions, to determine the contributions of consumer loads, as well as the contribution of background distortions. The simulation was carried out using the Simulink MatLab software (version R2023a). Several scenarios were considered in which the following values were varied: supply feeder impedance, level of background distortions, consumer electrical load composition, and passive filter parameters. It was found that the contribution of the background distortion source decreases with increasing impedance of the supply grid. It was determined that the consumer load contribution is independent of background voltage harmonics and can be used to estimate the overload of a passive harmonic filter. It was shown that it is necessary to take into account the overload of the passive filter by currents from background distortion sources, which did not exceed 135% of the rated rms current for the conditions under consideration. A mathematical model was proposed to estimate the overload of a passive filter in the presence of background voltage distortions. This model was obtained during analytical studies and allows one to evaluate the overload of a passive filter, taking into account the short circuit ratio, detuning frequency and power of the passive filter, and the share contribution of background distortion sources. [ABSTRACT FROM AUTHOR]

The issue of noise filtering for 3D systems is extremely important in voluminous data transmission. The challenge of this method is to regenerate unknown 3D noisy objects with distant transmission channels. This canal is modeled by convolution system and deconvolution filter to rebuild the output 3D object. To resolve this issue, firstly, we use the hybrid moments based on three Tchibechef, Krawtchouk, and Hahn polynomials to extract the feature vectors for generating the input system with the minimum information. Next, we implement the system with the model of Fornasini–Marchesini for convolution and deconvolution. However, the free matrix variables are used to eliminate coupling between Lyapunov matrix and system matrices to obtain sufficient conditions in linear matrix inequality form to ensure the desired stability and performance of the error systems. Furthermore, the 3D filtering error system is asymptotically stable and satisfies the H ∞ performance index. A comparative study was carried out to show the robustness of the MSE of the proposed method of hybrid descriptor of optimal order obtained by the maximum of maximum entropy for parameters p = 50, α = 50, and β = 50 compared to Tchebichef, Krawtchouk for p = 50, Hahn descriptors for α = 50, and β = 50 parameters. The proposed method is more efficient with a test MSE of 3.45, also the PSNR = 2, and ETIR of 48.1137 for 3D object with Zero-mean Gaussian noise of variance= 0,1. [ABSTRACT FROM AUTHOR]

As an essential passive component in modern wireless communication systems, the design of high-frequency filters has become increasingly crucial. To achieve the target behavior specifications, traditional design methods are constrained by designers' expertise or reliant on repetitive frequency sweeps using commercial software. Such processes suffer from low efficiency, limited applicability, and high computational costs. Artificial neural network-based modeling has become an important tool for designing devices. To realize accurate and fast electromagnetic modeling and design of passive components, this work proposes an inverse model integrating transfer functions and one-dimensional multi-channel convolutional neural networks (TF-1DMC-CNN). This model introduces transfer functions to ensure precise representation of electromagnetic responses while addressing the challenge of input dimensionality in wideband modeling. Input dimensions are reduced from 161 to 20 and 221 to 20 for two examples. The 1DMC-CNN processes distinct TF coefficients in each channel and extracts features in parallel. The geometrical parameters can be directly predicted in a single feedforward pass through the trained inverse model without needing iterative optimization. Compared to other inverse neural networks, the proposed model achieves the smallest testing errors. It obtains better model accuracy with fewer training samples, reducing data generation time. Compared to the traditional EM optimization method, this approach reduces CPU time for optimizations, enabling predictions of geometric structures that meet different design indexes. For multi-objective optimization, the proposed model predicts the structure within 0.16 seconds. [ABSTRACT FROM AUTHOR]

This paper was concerned with the problem of filter design for the continuous-discrete system in the Takagi-Sugeno (T-S) fuzzy model. In a known finite frequency (FF) domain, an FF $ H_\infty $ performance was defined for the nonlinear continuous-discrete system. With the designed filter, sufficient conditions were then established for the filtering error system to be asymptotically stable and having a prescribed FF $ H_\infty $ performance. After that, a systematic method for the filter design was proposed. Finally, an example was provided to check effectiveness of the derived results.

Digital filtering is a fundamental technique in digital signal processing, which operates on a digital sequence without any information on how the sequence was generated. This paper proposes a methodology for designing the equivalent of digital filtering for neuromorphic samples, which are a low-power alternative to conventional digital samples. In the literature, filtering using neuromorphic samples is performed by filtering the reconstructed analog signal, which is required to belong to a predefined input space. We show that this requirement is not necessary, and introduce a new method for computing the neuromorphic samples of the filter output directly from the input samples, backed by theoretical guarantees. We show numerically that we can achieve a similar accuracy compared to that of the conventional method. However, given that we bypass the analog signal reconstruction step, our results show significantly reduced computation time for the proposed method and good performance even when signal recovery is not possible. [ABSTRACT FROM AUTHOR]

The electrostatic gravity gradiometer carried by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite is affected by accelerometer noise and other factors; hence, the observation data present complex error characteristics in the low-frequency domain. The accuracy of the recovered gravity field will be directly affected by the design of the filters based on the error characteristics of the gradient data. In this study, the applicability of various filters to different errors in observation is evaluated, such as the 1 / f error and the orbital frequency errors. The experimental results show that the cascade filter (DARMA), which is formed of a differential filter and an autoregressive moving average filter (ARMA) filter, has the best accuracy for the characteristic of the 1 / f low-frequency error. The strategy of introducing empirical parameters can reduce the orbital frequency errors, whereas the application of a notch filter will worsen the final solution. Frequent orbit changes and other changes in the observed environment have little impact on the new version gradient data (the data product is coded 0202), while the influence cannot be ignored on the results of the old version data (the data product is coded 0103). The influence can be effectively minimized by shortening the length of the arc. By analyzing the above experimental findings, it can be concluded that the inversion accuracy can be effectively improved by choosing the appropriate filter combination and filter estimation frequency when solving the gravity field model based on the gradient data of the GOCE satellite. This is of reference significance for the updating of the existing models. [ABSTRACT FROM AUTHOR]

This paper deals with the issue of adaptive event-driven (AED) fault detection (FD) filter design for discrete-time networked control systems which is modeled by the Takagi–Sugeno (T–S) fuzzy model. First, a new AED scheme is designed to reduce the utilization of limited network resources. Compared with the existing works, the threshold of the AED scheme can be dynamically adjusted in real time by an adaptive law which utilizes the latest released data and the historical released data information. Then, an FD fuzzy filter with mismatched membership functions and AED mechanism is designed, which is used to generate a residual signal and detect system faults. A membership functions iteration strategy is utilized to optimize the membership functions of the FD fuzzy filter in real time, which can achieve better system performance. Furthermore, the sufficient conditions for designing the FD fuzzy filter are obtained in terms of the Lyapunov stability theory. Finally, a simulation example of the tunnel diode circuit system is utilized for proving the effectiveness and showing the advantages of the proposed AED FD strategy. By giving the initial values of relevant parameters, the MATLAB LMI toolbox is used to solve the result experiment. [ABSTRACT FROM AUTHOR]

Introduction: SPECT is reconstructed using iterative techniques incorporating photon attenuation correction based on the X ray transmission map and scatter correction. Since the quality of image in SPECT scans depends on the imaging parameters that are determined experimentally in the field of nuclear medicine, designing a dedicated scanning method for 99mTc/SPECT is need to improve the accuracy of disease diagnostic. Therefore, in this study with the aims of assessment and evaluation the effect of different filters on image quality, assessment of quality criteria on image before and after optimization and determine optimum algorithm for reconstruction on liver scanning using 99m Tc for SPECT studies. Material and Method: Filtered Back-projection reconstruction method had been used in liver scanning using 99m Tc/EDDA/HYNIC-TOC for SPECT image and effect of different filters on SPECT imaging have been evaluated. Results and Conclusion: Based on results, we suggest the Hamming filter to be used for visual analysis of Liver SPECT because of its ability to produce the high-quality image. Instead, the Butterworth filter is suggested for quantitative analysis because of its ability to balance between image quality and noise.

In this paper, a new optimization method for the design of nearly linear-phase two-dimensional infinite impulse (2D IIR) digital filters with a separable denominator is proposed. A design framework for 2D IIR digital filters is formulated as a nonlinear constrained optimization problem where the group delay deviation in the passband is minimized under prescribed soft magnitude constraints and hard stability requirements. To achieve this goal, sub-level sets of the group delay deviations are utilized to generate a sequence of filters, from which the one with the best performance is selected. The quality of the obtained filter is evaluated using three quality factors, namely, the passband magnitude quality factor Qh and the group delay deviation quality factor Qτ, while the third one is a new quality factor Qs that assesses the performance in the stopband relative to the minimum filter gain in the passband. The proposed framework is implemented using the interior-point (IP) method in a MATLAB environment, and the experimental results show that filters designed using the proposed method have good magnitude response and low group delay deviation. The performance of the resulting filters is compared with the results of other methods.

In recent decades, there have been individual cases of damage to the revetments of the German North Sea estuaries due to clogging by precipitated ochre products. This process is defined as ochre clogging and has been extensively explained in the literature. The primary aim of the investigations was to better understand the clogging process under in situ conditions and the causative environmental conditions surrounding the filters. Extensive in situ investigations were therefore carried out. It was found that a permeability reduction in geotextile filters can be strongly accelerated by ochre clogging, which appears to be a biogeochemical process. This describes a combined action of the chemical precipitation of iron and manganese, precipitation by microorganisms, and physical clogging. A further aim of this study was to establish limit values for the decisive ochre clogging parameters, which could be used to quantify the susceptibility to ochre clogging. It was shown that the determination of the iron and manganese content of the groundwater, as well as the redox capacity of the groundwater, is sufficient to assess the tendency for ochre clogging. To minimise the negative impact on filter performance, recommendations for an adapted filter design have been developed as a guide for planners.

Digital filter design optimization counts as one of the most challenging problems in circuit development. Furthermore, the bit-width allocation has a crucial impact on the efficiency and accuracy of fixed-point digital filters. The conventional implementation procedure involves studying the bit-width allocation problem after determining the filter coefficients. This sequential procedure leads frequently to an excessive bit-width allocation, hence an extra implementation cost. The main contribution of this paper is to propose a new implementation procedure based on the simultaneous handling of both design issues and the bit-width optimization for the infinite impulse response filter. In this study, the problem is formalized by a multi-objective programming technique using the non-dominated sorting genetic algorithm II. The joint consideration of the two problems offers a better trade-off between design and bit-width allocation. The output of our approach is compared to the results of existing algorithms. Simulation results show that the multi-objective method significantly reduces the implementation cost while ensuring filter stability and an acceptable mean square error (MSE) compared to the existing algorithms. [ABSTRACT FROM AUTHOR]

The design problem of l1 filters was studied for a class of discrete-time switched singular systems with positive constraints and time-varying delays. Through construction of an appropriate co-positive Lyapunov function and with the average dwell time technique, sufficient conditions in the form of linear programming were provided to ensure the corresponding filtering error system to be positive, regular, causal and exponentially stable. In addition, the effect of the exogenous disturbance input on the system performance was also analyzed and discussed. The sufficient conditions and design mechanisms for the corresponding filter to ensure that the filtering error system has the prescribed l1 disturbance attenuation performance were also given. Finally, a simulation example was provided to verify the effectiveness and feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, two new subdesign tools including the quasi‐static and fuzzy model calculations for the electrical parameters of the coupled planar transmission lines used in the design of microwave communication subsystems including resonators, filters, and multiplexers are presented for CADMFILT software. Proposed subdesign tools have properties such as electrical parameter calculations for microwave circuit analysis/synthesis, fuzzy logic model applications, comparisons, and graphical demonstrations. The first subdesign tool can calculate the electrical parameters of the coupled planar transmission lines by using the quasi‐static analysis method. The other tool is based on subtractive fuzzy clustering, which can offer approximate solutions as an alternative to numerical and analytical closed‐form expressions of quasi‐static analysis. The proposed subdesign tools have a competent and efficient algorithm to provide fast, accurate, and sensitive results. To test the accuracy of these tools, a coupled coplanar waveguide with a single ground plane structure has been performed. The results obtained from the subdesign tools for both approaches have been compared. The proposed fuzzy logic models use the electrical parameters calculated from the quasi‐static analysis as training and control data files. The accuracy of each model has been tested by error analysis and the validity of the model results has been demonstrated by comparing them with the results of the quasi‐static approach. It is expected that the developed efficient, fast, and versatile subdesign tools will help researchers to simplify their designs by providing a control mechanism in the RF/microwave circuit design processes. [ABSTRACT FROM AUTHOR]

This article presents a rigorous synthesis method of a transmission-line filter whose second passband can be placed at any multiple of the center frequency, in theory. Two coupled-line schematics for harmonic-controlled bandpass filters are derived from fundamental LC filter prototypes. Their design parameters are provided in closed-form expressions so filter dimensions can be acquired rigorously without relying on EM-simulation-based coupling tests. Three filters were designed and fabricated for verification purposes, and their measurement results exhibited excellent agreement with the theory.

This paper discusses the issues of assessing the influence of external distortion sources on the functioning of a shunt passive harmonic filter. In this study, we evaluated the overload of a passive harmonic filter based on determining the contributions of distortion sources. A method was proposed for assessing the contributions of distortion sources, which allowed us, regardless of background distortions, to determine the contributions of consumer loads, as well as the contribution of background distortions. The simulation was carried out using the Simulink MatLab software (version R2023a). Several scenarios were considered in which the following values were varied: supply feeder impedance, level of background distortions, consumer electrical load composition, and passive filter parameters. It was found that the contribution of the background distortion source decreases with increasing impedance of the supply grid. It was determined that the consumer load contribution is independent of background voltage harmonics and can be used to estimate the overload of a passive harmonic filter. It was shown that it is necessary to take into account the overload of the passive filter by currents from background distortion sources, which did not exceed 135% of the rated rms current for the conditions under consideration. A mathematical model was proposed to estimate the overload of a passive filter in the presence of background voltage distortions. This model was obtained during analytical studies and allows one to evaluate the overload of a passive filter, taking into account the short circuit ratio, detuning frequency and power of the passive filter, and the share contribution of background distortion sources.

Eliminating the Gibbs oscillations that occur during the Finite Impulse Response (FIR) digital filter design with the Fourier Series method will ensure correct filtering. For this reason, the development of the window improves the performance of the filter and, therefore, the system. In this study, the cosh window function is designed using Particle Swarm Optimization, which is a preferred optimization method in many areas. Thus, alternatives to the standard results obtained from the existing traditional calculations will be produced, and different windows that perform the same function will be obtained. In addition, exponential and cosh window functions were designed in LabVIEW environment, which is a graphical programming language-based program, and the designed windows were analyzed at different parameter values. LabVIEW provides a fast and easy programming environment, and it provides the opportunity to realize real-time applications with its external hardware. Utilizing this feature, the amplitude spectrum of cosh window designed in LabVIEW is displayed in real time for different window parameter values. As a result, FIR digital filters were designed using cosh window based on optimization and the cosh window designed in LabVIEW, and the distorted EEG signal was filtered using these filters and displayed in real time. [ABSTRACT FROM AUTHOR]

Objectives: The filtering of colored noise and low-frequency systematic errors of gravity gradient data from gravity field and steady-state ocean circulation explorer (GOCE) satellite is a key issue in the inversion of high-precision Earth gravity fields. Methods: For the filtering of GOCE satellite gravity gradient data, we design two kinds of low-frequency systematic error filters based on moving average (MA) method and circle per revolution (CPR) empirical parameter method, and then combine them with the colored noise filter based on auto-regressive moving average (ARMA) model to form cascaded filters. To analyze the actual effect of these filters, the gravity field models GOGR-MA (MA+ARMA cascade filtering) and GOGRCPR (CPR+ARMA cascade filtering) gravity field models of order 224 are inversed by using 70 d of GOCE data based on the space-wise least square method, respectively. The inversion models are compared with the first generation of GOCE series models, and GOCE and GRACE combined model GOCO01S solved by contemporaneous data. Then the model is checked by high-precision global positioning system leveling data and mean dynamic topography model. Results: The results show that both the MA filter and CPR empirical parameter filter can weaken the influence of low-frequency system errors, and the latter is better. Moreover, ARMA decorrelation filter can effectively whiten the colored noise of gravity gradient data. The combined models GOGR-MA and GOGR-CPR have similar accuracy and they perform better than GOCO01S model developed by European Space Agency (ESA) using the same period data. Conclusions: The inversion results verify the correctness and effectiveness of the proposed cascaded filters, which can provide a reference for filtering of GOCE gravity gradient data and inversion of high-precision gravity field. [ABSTRACT FROM AUTHOR]

To solve the problems of sluggish convergence at local minima, a combination of reptile search algorithms with differential evolution (CRSADE) has been developed. The conglomerated algorithm also includes a lens opposition-based learning method, which boosts population diversity and speeds up convergence. The differential evolution algorithm used in the developed CRSADE improves the exploration of the reptile search algorithm through its high ability to locate feasible regions with the best solution. This accelerates convergence by enhancing the end product of the algorithm. The proposed CRSADE helps in designing finite impulse response filters in which absolute error difference is utilized as a fitness function which is minimized by the proposed CRSADE to obtain optimal filter coefficients. To demonstrate its superiority and consistency, a comparison has been made between the developed method and other existing optimization algorithms. The developed filter satisfies the intended objective effectively with lower ripples in the pass band and higher attenuation in the stop band. [ABSTRACT FROM AUTHOR]

A compact topology for implementing compact multiband bandpass filters is presented in this paper. To achieve the desired frequency response, two identical short-circuited multiconductor transmission lines (MTLs) and properly connected shunt open stubs are interconnected. Using this configuration, it is possible to design multiband bandpass filters effortlessly. As both the MTLs and the stubs are distributed elements, spur-line band-stop filters are added to mitigate the first replica of the structure's frequency response. To assess the behavior of the developed filter design procedure, a prototype consisting of a six fingers-MTL and two shunt open stubs has been designed, manufactured, and analyzed, showing excellent agreement between analytical and measured results, considering that no simulation or optimization process has been performed during the design process, just for result verification. Furthermore, it is possible to establish a design criterion that allows the fast and reliable synthesis of multiband responses by varying just a small number of geometrical parameters of the MTLs and the corresponding stubs. [ABSTRACT FROM AUTHOR]

Even though today's electromagnetic compatibility (EMC) standards and measurement techniques set specific limitations and a clear methodology to measure the conducted emissions (CE) of equipment under tests (EUTs), the design methodology of a suitable power-line filter (PLF) to solve non-compliance is, in general, neither accurate nor efficient. This is due to different reasons, such as unknown actual load and line impedances, unknown dominant mode in the CE, and/or inappropriate instrumentation for the appropriate measurements. The objective of this paper is to investigate if different topologies of switching mode power supplies (SMPSs) lead to different PLF structures. For the sake of exemplification, the analysis is focused on switched-mode DC-DC converters. From an EMC point of view, these devices can be completely modeled by means of Scattering (S)–parameter and CE measurements. Additionally, an analysis of their circuit models has been performed to allow a better comprehension of their characterization. In this paper, the circuit models of three different types of DC-DC converters are presented, and their component values (including nonlinearities and parasitic effects introduced by the actual behavior of the circuit elements) are estimated using the S-parameter characterization. Then, a new methodology for PLF design, based on accurate insertion loss (IL) estimations, is applied to obtain the optimal PLF for one of the converters. This methodology is experimentally tested and validated. [ABSTRACT FROM AUTHOR]

This article presents a method for calculating all the proportional–integral/proportional–derivative controllers with a low-pass filter of a given order, which satisfy gain–phase margins and sensitivity (or complementary sensitivity) specifications. The method is explicit and requires solving a set of a polynomial and two linear equations. It is shown how to extend the method to design all the proportional–integral–derivative or cascaded controllers with a low-pass filter assuming that a minimum value of one of the controller components is given. [ABSTRACT FROM AUTHOR]

Heap-Based Optimizer (HBO) is one of the recently proposed metaheuristic algorithms inspired by the corporate rank hierarchy. In this study, opposition and Cauchy-based search mechanisms are integrated into HBO which is applied for the design of high-order Butterworth active filters, for the first time, comparing with six outstanding metaheuristics introduced for the last year (2020). In addition, the proposed algorithm has been adapted to solve the benchmark presented in the IEEE-CEC 2020 competition to demonstrate its effectiveness against numerical functions. The analog filter design is a challenging problem due to its discrete topology and complex search space. This study provides a comprehensive review for the design of these filters with the up-to-date algorithms: firstly, the performance of each metaheuristic is analyzed by its error value performance, the required number of iterations to achieve this error value; secondly, a statistical test is conducted to validate its performances; as the third, convergence abilities of algorithms are compared with respect to the total design process error values versus an iteration number graph. The passive component values of the Butterworth active filter are selected within the E24 and E96 industrial series so as to make the realization of designs easier to the real world. To demonstrate the suitability of the components obtained by the algorithms to the real world, the amplitude response of the associated design is given. The simulation results demonstrate the effectiveness of the proposed algorithm over the contestant algorithms, and its capability of solving these case design problems. This extensive work can also provide guidelines to the researchers for future studies. [ABSTRACT FROM AUTHOR]

Digital filtering is a fundamental technique in digital signal processing, which operates on a digital sequence without any information on how the sequence was generated. This paper proposes a methodology for designing the equivalent of digital filtering for neuromorphic samples, which are a low-power alternative to conventional digital samples. In the literature, filtering using neuromorphic samples is performed by filtering the reconstructed analog signal, which is required to belong to a predefined input space. We show that this requirement is not necessary, and introduce a new method for computing the neuromorphic samples of the filter output directly from the input samples, backed by theoretical guarantees. We show numerically that we can achieve a similar accuracy compared to that of the conventional method. However, given that we bypass the analog signal reconstruction step, our results show significantly reduced computation time for the proposed method and good performance even when signal recovery is not possible.

The electrostatic gravity gradiometer carried by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite is affected by accelerometer noise and other factors; hence, the observation data present complex error characteristics in the low-frequency domain. The accuracy of the recovered gravity field will be directly affected by the design of the filters based on the error characteristics of the gradient data. In this study, the applicability of various filters to different errors in observation is evaluated, such as the 1/f error and the orbital frequency errors. The experimental results show that the cascade filter (DARMA), which is formed of a differential filter and an autoregressive moving average filter (ARMA) filter, has the best accuracy for the characteristic of the 1/f low-frequency error. The strategy of introducing empirical parameters can reduce the orbital frequency errors, whereas the application of a notch filter will worsen the final solution. Frequent orbit changes and other changes in the observed environment have little impact on the new version gradient data (the data product is coded 0202), while the influence cannot be ignored on the results of the old version data (the data product is coded 0103). The influence can be effectively minimized by shortening the length of the arc. By analyzing the above experimental findings, it can be concluded that the inversion accuracy can be effectively improved by choosing the appropriate filter combination and filter estimation frequency when solving the gravity field model based on the gradient data of the GOCE satellite. This is of reference significance for the updating of the existing models.

The traditional swarm intelligence optimization algorithm is prone to fall into local optimal solutions in finite impulse response (FIR) digital filter design and has slow convergence speed. In order to optimize the design of FIR filter, a FIR digital filter design method based on improved bee colony (ABC) algorithm is proposed. This improved ABC algorithm can adaptively adjust the step size of the selected neighborhood of nectar source location. At the same time, the information of the global optimal solution is used to guide the search of candidate solution, which improves the global search ability of the algorithm. The improved ABC algorithm can balance the conflict between local search ability and global search ability, so it can achieve better optimization effect. The time and space complexity of the algorithm is analyzed in detail. Then, the improved ABC algorithm is used to design three typical FIR digital filters, namely low-pass, band-pass and band-stop filter. The performance of the designed filter is tested by simulation experiments. The experimental results show that compared with other state-of-the-art optimization algorithms, the proposed FIR filter design method has achieved better effect and performance. Meanwhile, the proposed design method has shorter optimization time. The superiority of the proposed method is verified. [ABSTRACT FROM AUTHOR]

This paper is concerned with the design of positive L1$$ {L}_1 $$ filter for positive Markovian jump systems (PMJSs) with adaptive event‐triggered mechanism and quantization. Considering the mode jump of the system, a new adaptive event‐triggered condition is established, which not only can regulate the communication threshold according to the error of dynamic systems, but also can avoid the asynchronous phenomenon between the system mode and the filter mode. In order to further reduce the burden of communication, a new positive L1$$ {L}_1 $$ filter with the quantized measure system output is developed, and the design condition which ensures the filter error system to be stochastically stable with L1$$ {L}_1 $$ performance is presented which can be solved in terms of linear programming (LP) technique. It is illustrated that there is no Zeno phenomenon. The proposed results are applied to the power allocation in a mobile telecommunication system, and it is shown that compared with the existing results, the event‐triggered filter of this paper has some advantages. [ABSTRACT FROM AUTHOR]

Deformation-rate distributed acoustic sensing (DAS), made available by the unique designs of certain interrogator units, acquires seismic data that are theoretically equivalent to the along-fiber particle velocity motion recorded by geophones for scenarios involving elastic ground-fiber coupling. While near-elastic coupling can be achieved in cemented downhole installations, it is less obvious how to do so in lower-cost horizontal deployments. This investigation addresses this challenge by installing and freezing fiber in shallow backfilled trenches (to 0.1 m depth) to achieve improved coupling. This acquisition allows for a reinterpretation of processed deformation-rate DAS waveforms as a "filtered particle velocity" rather than the conventional strain-rate quantity. We present 1D and 2D filtering experiments that suggest 2D velocity-dip filtering can recover improved DAS data panels that exhibit clear surface and refracted arrivals. Data acquired on DAS fibers deployed in backfilled, frozen trenches were more repeatable over a day of acquisition compared to those acquired on a surface-deployed DAS fiber, which exhibited more significant amplitude variations and lower signal-to-noise ratios. These observations suggest that deploying fiber in backfilled, frozen trenches can help limit the impact of environmental factors that would adversely affect interpretations of time-lapse DAS observations. [ABSTRACT FROM AUTHOR]

We propose a class of fully differential filters based on a common-gate differential amplifier cell in three different topologies. Our focus is on the synthesis of second-order band-pass filters and we found 53 possible circuits. All filters are resonance-based and have electronically tunable gain. Post layout simulations in 65-nm CMOS technology are provided to validate the proper function of these filters. [ABSTRACT FROM AUTHOR]

In this brief, the finite-time peak-to-peak filter design problem is investigated for discrete-time nonlinear singular system. The T-S fuzzy model is introduced to represent the considered nonlinear system. First, a useful analysis method is proposed to detect whether the resulting filtering error system is singular finite-time bounded and guarantees the peak-to-peak performance. Further, in order to cope with the difficulty caused by the special form of filtering error system, we propose a novel filter form which facilitates the elimination of the coupling items in the filter design. And based on this, the sufficient design scheme for finite-time peak-to-peak filter is formulated by means of standard linear matrix inequality technique. Finally, a tunnel diode circuit is used to illustrate the feasibility and effectiveness of the developed algorithm. [ABSTRACT FROM AUTHOR]

Digital Signal Processing (DSP) and communication applications utilise a Finite Impulse Response (FIR) filter which is key component for digital communication. Moreover, quality of signal is enhanced by FIR filter which is mostly employed by filtering applications. The execution speed of the FIR is determined by multiplier's performance. Hardware resource utilisation and speed-up operations are some of the issues found in existing methods which are occurred due to a critical path in incomplete products. So, this can be improved by the proposed optimisation algorithm based multiplier. This research establishes the execution of FIR Filter design using Red Deer Optimisation (RDO) based Wallace Tree (WT) multiplier. By using the optimised WT multiplier, FIR filter is simulated to examine the area, delay, power and frequency for different tap FIR filter. Moreover, FIR filter with optimised WT is introduced to perform signal denoising application. Proposed multiplier design is simulated using Xilinx tool. Filtering simulation is done by using the publicly available database named as MIT-BIH database and the noise removal process is simulated using Matlab tool. The FIR filter designed with proposed multiplier provides delay around 1.373 ns and consumes 0.143 W as total power which is lesser than the existing methods. [ABSTRACT FROM AUTHOR]

Optimal detection filters can greatly enhance fault detection performance, but designing these filters requires fault data which is difficult to obtain in practice. This paper proposes a scheme that automatically determines the optimal detection filter from a filter bank online without using fault data. The method can improve fault detection rate and accelerate detection speed. In order to reduce the false alarm rate, a method of threshold setting is introduced based on kernel density estimation. Implementation issues concerning filter bank design and online decision rule are also discussed. The method is validated in a numerical example and Tennessee Eastman process, and its performance is compared to those of other state-of-the-art methods. • Enabling automatic determination of optimal fault detection filter. • Using kernel density estimation to refine the thresholds. • Enhancing fault detection performance without using fault data. • Performance validated in Tennessee Eastman benchmark. [ABSTRACT FROM AUTHOR]