Suitable Filter Research Articles

Distributed Bipartite Consensus of Multi-Agent Systems via Disturbance Rejection Control Strategy

This work aims to focus on analyzing the consensus control problem in cooperative–competitive networks in the occurrence of external disturbances. The primary motive of this work is to employ the equivalent input-disturbance estimation technique to compensate for the impact of external disturbances in the considered multi-agent system. In particular, a suitable low-pass filter is implemented to enhance the accuracy of disturbance estimation performance. In addition, a specific signed, connected, and structurally balanced undirected communication graph with positive and negative edge weights is considered to express the cooperation–competition communication among neighboring agents. The cooperative–competitive multi-agent system reaches its final state with same magnitude and in opposite direction under the considered structurally balanced graph. By utilizing the properties of Lyapunov stability theory and graph theory, the adequate conditions assuring the bipartite consensus of the examined multi-agent system are established as linear matrix inequalities. An illustrative example is delivered at the end to check the efficacy of the designed control scheme.

Selection of suitable filter materials for subsurface flow constructed wetland systems for wastewater treatment in rice noodle handicraft village

This study aims to select suitable filter materials for Subsurface Flow Constructed Wetlands (SSF CW) to treat wastewater from rice noodle handicraft villages, based on a combination of new materials (plastic waste and rice husk) and traditional substrates (limestone, gravel, and sand). Four SSF CW models using different filter materials were tested during three months, including CW1 (limestone, gravel, and sand), CW2 (sand, plastic waste, and gravel), CW3 (sand + rice husk, limestone, and gravel), and CW4 (sand + rice husk, plastic waste, and gravel). The results indicated that CW3 and CW4 systems were more effective to plant growth. Replacing limestone with plastic waste did not show a significant difference in treatment efficiency (p > 0.05), however the addition of rice husk decreased the efficiency of organic matter treatment while increasing nutrient treatment efficiency (p < 0.05). The highest treatment efficiencies for TSS and COD were observed in CW1, at 83.89 ± 1.38 % and 79.56 ± 1.36 %, respectively. Meanwhile, the highest treatment efficiencies for TN, NH4+, and TP were recorded in CW4, at 80.14 ± 2.76 %, 88.39 ± 1.62 %, and 82.22 ± 2.51 %, respectively. The effluent water from all four SSF CW models met the Vietnamese standard for wastewater quality (QCVN 40:2011/BTNMT, column B). This study demonstrates the potential of using a combination of plastic waste, rice husk, and sand as suitable filter substrates for SSF CW in treating wastewater from rice noodle handicraft villages.

Coupling adaptive filters with acoustic travel time tomography for indoor climate measurements in occupied room conditions

Acoustic travel time TOMography (ATOM) as a remote sensing technique allows for the measurement of indoor climate parameters, such as air temperature and airflow velocity distributions. The performance of ATOM in monitoring indoor air temperature in empty room conditions was evaluated recently, utilizing a combined analysis approach of room acoustics and tomography. This study shifts focus to the assessment of ATOM in an occupied room condition where fixed objects are introduced to the test area. The presence of objects in a room can result in notable shifts in the travel times of individual reflections. In some cases, these shifts can cause reflections to disappear completely or be replaced by new ones. These partial disruptions in the reflection pattern present challenges in obtaining accurate information about the room's temperature. To ensure the accurate identification of undisturbed reflection paths, an algorithm was developed that can convert distorted signals into a pure reference signal using a suitable adaptive filter. The measurement results confirm the validity of the approach for a temperature interval of 4°C where the system was trained for two temperatures of 20°C and 24°C in a climate chamber.

Stabilization of LTI systems with both uncertainties and external disturbances via DE-based control method

This paper is concerned with the stabilization of linear time-invariant (LTI) systems with unknown parameters and external disturbances. Firstly, four types of suitable filters are presented and applied to achieve the accuracy estimate of the disturbances. Based on these filters, four types of disturbance estimators are designed and used to asymptotically cancel the corresponding disturbances. Secondly, an adaptive disturbance estimator (DE)-based control method is obtained by combining the adaptive control method with the DE-based control method. It is noted that the algebraic representation of the adaptive feedback control law is given in a more concise form by the tool of the semi-tensor product of matrix. Further, the stabilization of LTI systems is achieved by the obtained adaptive DE-based control method. Finally, three numerical examples with computer simulation are provided to verify the correctness and validity of the obtained theoretical methods.

GENERALIZATION OF THE TIME INFINITE IMPULSE RESPONSE DIGITAL FILTERS

This work describes the generalization of a new kind of infinite impulse response (IIR) digital filter to filter the pulse signal periods. This kind of digital filter was designed using the previously designed frequency-locked loops (FLL), which are based on the time measurement and processing of both the input and output periods. FLL is a linear discrete system. Starting from the general form of difference equation of the IIR FLL digital filter of the third and fourth orders, the transfer functions and Z transform of the outputs are developed for the IIR FLL digital filter of any order. To demonstrate the capabilities and utility of the general equations, they were applied to design a suitable IIR digital filter using a fourth-order FLL. The filtering abilities and the analyses in the frequency domain of the designed low pass IIR digital filter are demonstrated using the theory of IIR digital filter and the corresponding MATLAB tools. Analyses of the fourth-order IIR FLL digital filter were also performed in the time domain using computer simulation in MATLAB.

Rapid and Cost‐Effective Platypus eDNA Detection in Waterways Using Loop‐Mediated Isothermal Amplification Assay: Advancing Conservation Efforts

ABSTRACTFreshwater ecosystems, home to a remarkable diversity of species, are facing severe threats from human activities such as climate change, habitat degradation, over‐extraction of water for irrigation, and pollution. The platypus, an iconic species in freshwater ecosystems around Australia, is threatened by all these activities, both singly and in combination. The scale and complexity of these intersecting and reinforcing threats makes cost‐effective monitoring tools essential to better understand how platypus populations are responding. In this study, we optimized a loop‐mediated isothermal amplification (LAMP) assay for the rapid and cost‐effective detection of platypus DNA in environmental water samples, offering an attractive alternative to quantitative polymerase chain reaction (qPCR). We improved a water filtration protocol for in‐field use, employing suitable filter membranes for processing large volumes of water, thereby maximizing DNA recovery from dilute samples. The limit of detection for the platypus LAMP (Plat‐LAMP) assay was determined to be 12.4 copies/μL using a standard plasmid positive reference and 7 × 10−6 ng/μL when applied to DNA extracted from platypus tissue, with improved sensitivity achieved through the incorporation of locked nucleic acid primers. In comparative testing against qPCR, the Plat‐LAMP assay exhibited greater sensitivity in detecting platypus DNA in known positive water samples collected from platypus habitat at Healesville Sanctuary. Furthermore, the Plat‐LAMP assay demonstrated 100% specificity when performed on water samples collected from non‐platypus habitats. In field testing across waterways in Victoria and New South Wales, the Plat‐LAMP assay detected platypus in 36.96% of samples, compared to 54.35% of samples using qPCR. These findings underscore the Plat‐LAMP assay's potential as a faster and more cost‐effective complementary method to qPCR, rendering it suitable for point‐of‐application water testing. The ability to conduct eDNA surveys without the need for cold‐chain logistics would significantly assist conservation organizations and water managers map platypus distributions and facilitate conservation efforts around Australia.

MBE-grown ZnTe epitaxial layer based broadband photodetector with high response and excellent switching characteristics

Zinc telluride (ZnTe) epitaxial layers were grown on gallium arsenide (GaAs) (211) substrate at different growth temperatures by molecular beam epitaxy. The fabricated interdigitated metal semiconductor metal configuration-based photodetector (PD) on ZnTe epitaxial layers exhibited a stable and excellent photo response in a broad spectral range (250–550 nm) up to 125 °C. The room temperature and higher temperature (125 °C) values of maximum current, spectral responsivity and detectivity at an applied bias of 5 V and 550 nm wavelength were 3.5 × 10−8 A, 0.1 A W−1 and 1 × 1011 Jones and 1.7 × 10−6 A, 2.5 A W−1 and 1.5 × 1011 Jones, respectively. The maximum photo-to-dark-current ratio (PDCR) value at zero bias and 100 °C was obtained for the ZnTe layer grown at an optimum growth temperature of 380 °C. The high PDCR value exhibits the self-powered capability of the detector. Furthermore, the detector exhibits good on–off switching to the illuminating light with rise and decay times less than 0.29 s and 0.4 s, respectively, at room temperature. The dependence of the photo response on material quality was analysed by varying the substrate growth temperature. The broadband responsivity of the ZnTe-based PD shows its capability as a multicolour detector in the UV and visible region with the use of suitable blocking filters.

Development and performance simulations of a soft X-ray and XUV split-and-delay unit at beamlines FL23/24 at FLASH2 for time-resolved two-color pump-probe experiments.

The split-and-delay unit (SDU) at FLASH2 will be upgraded to enable the simultaneous operation of two temporally, spatially and spectrally separated probe beams when the free-electron laser undulators are operated in a two-color scheme. By means of suitable thin filters and an optical grating beam path a wide range of combinations of photon energies in the spectral range from 150 eV to 780 eV can be chosen. In this paper, simulations of the spectral transmission and performance parameters of the filter technique are discussed, along with a monochromator with dispersion compensation presently under construction.

Film Temperature And Thickness Measurements Of An Impinging Oil Jet For Cooling Of Electric Components Based On Two-Color Laser-Induced Fluorescence.

A fluorescence based two-color detection scheme is used to characterize a jet impingement cooling process relevant for electric and electronic applications. The presented technique enables a simultaneous determination of film temperature and film thickness. The fluorescence signal was generated by the temperature-sensitive fluorescence tracer nile red, which was added to Marlotherm LH, a commercially available heat transfer oil. Suitable band pass filters enable accurate temperature measurements. A preliminary spectral study investigates the influence of dye concentration, temperature and film thickness. At high dye concentrations (up to 37.5 mg/L) reabsorption effects takes place and lead to a spectral shift towards higher wavelengths with increasing film thickness. Low dye concentrations (0.59 mg/L) exhibit no film thickness dependent spectral shift. A film temperature investigation at low dye concentration showed no bias of the intensity ratio due to film thickness, i.e. no additional spectral shift towards lower wavelengths was observed. The investigations on the jet impingement setup revealed an increasing film temperature and decreasing film thickness with increasing solid temperature. The average film temperature increases with increasing solid temperature from 298 K (solid temperature 298 K) to 308 K (solid temperature 398 K). At higher solid temperatures, the film temperature increases with distance to the stagnation zone. The average film thickness decreases with increasing solid temperature from 0.24 mm to 0.17 mm. At high solid temperatures, the film temperature increased with radial distance to the stagnation zone. This behavior is caused by the increasing temperature gradient with increasing solid temperature and decreasing viscosity with increasing film temperature.

CenterTrack-EKF: 확장된 칼만 필터를 이용한 개선된 다중 객체 추적

Multi-Object trajectory modeling is a major challenge in MOT. CenterTrack tried to solve this problem with a Heatmap-based method that tracks the object center position. However, it showed limited performance when tracking objects with complex movements and nonlinearities. Considering the degradation factor of CenterTrack as the dynamic movement of pedestrians, we integrated the EKF into CenterTrack. To demonstrate the superiority of our proposed method, we applied the existing KF and UKF to CenterTrack and compared and evaluated it on various datasets. The experimental results confirmed that when EKF was integrated into CenterTrack, it achieved 73.7% MOTA, making it the most suitable filter for CenterTrack.

Quality of Life and Respiratory Performance in the Laryngectomized Patient: Role of the HME Filters during Physical Activity.

Background: Permanent tracheostomy because of total laryngectomy surgery entails significant consequences for patients regarding respiratory physiopathology, such as the loss of the filtering, humidifying, and heating of air by the nose. The use of special stomal filters can provide adequate protection of the tracheal-bronchopulmonary system with a reduction in respiratory pathologies. In fact, in most cases, laryngectomy patients are first cigarette smokers who for this reason also already have respiratory diseases such as chronic obstructive pulmonary disease (COPD). Despite the availability of tracheal filters, as reported in the literature, patients often tend to limit their use due to reported breathing difficulties, especially in conditions of intense breathing. Methods: The objective of this clinical study was to evaluate the most suitable stomal filter for laryngectomy patients during physical activity. The filters studied were an INHEALTH device (Blom-Singer SpeakFree HME); two ATOS devices (Provox® Life™ Energy HME and Provox® Life™ Home HME); and an FAHL device (Laryvox HME Sport). Results: For this purpose, the performances of 31 laryngectomy patients, subjected to medium-high physical effort, were analyzed through a standardized pneumological test, the Six Minute Walking Test (6MWT), which involves a sustained walk lasting six minutes, with an evaluation of heart rate, oxygen saturation, and meters traveled every 60 s; furthermore, we examined two subjective indices, namely, the basal and final dyspnea index and the initial and final muscular fatigue index. Conclusions: The multidisciplinary approach of the laryngectomee patient must also take pulmonary rehabilitation into consideration. It is the task of the medical team and speech therapy support to help the patient in the correct choice of HME filters taking into account daily needs.

Group-Invariant Max Filtering

AbstractGiven a real inner product space V and a group G of linear isometries, we construct a family of G-invariant real-valued functions on V that we call max filters. In the case where $$V={\mathbb {R}}^d$$ V = R d and G is finite, a suitable max filter bank separates orbits, and is even bilipschitz in the quotient metric. In the case where $$V=L^2({\mathbb {R}}^d)$$ V = L 2 ( R d ) and G is the group of translation operators, a max filter exhibits stability to diffeomorphic distortion like that of the scattering transform introduced by Mallat. We establish that max filters are well suited for various classification tasks, both in theory and in practice.

Simulation application of sensors based on Kalman filter algorithm in student psychological crisis prediction model

The mental health and psychological crisis of some Chinese college students today are extremely abnormal, which has attracted the attention of many relevant personnel. Due to various external reasons, the psychological construction of Chinese college students is very pessimistic. Kalman filter is a regression calculation method for processing data. The standard calculation of this filter has the smallest data error, so that relevant data can be recursive. Within the relevant time domain, this calculation method can select suitable filters to accurately calculate high-dimensional and low-dimensional system data. This paper mainly solves some problems encountered, thus proving the effectiveness of Kalman filter calculation method. Finally, we can get the advantages and disadvantages of these filter systems, so as to improve these disadvantages, and finally improve the Rate of convergence of this calculation method. Through the corresponding experimental results, we can see that these calculation methods are correct. By analyzing these data, the analysis results show that this calculation method can effectively predict students' mental health problems, and the designed system can reduce the occurrence of psychological crisis events among college students.

Measurement and Analysis of In Vivo Gastroduodenal Slow Wave Patterns Using Anatomically-Specific Cradles and Electrodes.

Bioelectrical 'slow waves' regulate gastrointestinal contractions. We aimed to confirm whether the pyloric sphincter demarcates slow waves in the intact stomach and duodenum. We developed and validated novel anatomically-specific electrode cradles and analysis techniques which enable high-resolution slow wave mapping across the in vivo gastroduodenal junction. Cradles housed flexible-printed-circuit and custom cradle-specific electrode arrays during acute porcine experiments (N = 9; 44.92 kg ± 8.49 kg) and maintained electrode contact with the gastroduodenal serosa. Simultaneous gastric and duodenal slow waves were filtered independently after determining suitable organ-specific filters. Validated algorithms calculated slow wave propagation patterns and quantitative descriptions. Butterworth filters, with cut-off frequencies (0.0167 - 2) Hz and (0.167 - 3.33) Hz, were optimal filters for gastric and intestinal slow wave signals, respectively. Antral slow waves had a frequency of (2.76 ± 0.37) cpm, velocity of (4.83 ± 0.21) mm·s-1, and amplitude of (1.13 ± 0.24) mV, before terminating at the quiescent pylorus that was (46.54 ± 5.73) mm wide. Duodenal slow waves had a frequency of (18.13 ± 0.56) cpm, velocity of (11.66 ± 1.36) mm·s-1, amplitude of (0.32 ± 0.03) mV, and originated from a pacemaker region (7.24 ± 4.70) mm distal to the quiescent zone. Novel engineering methods enable measurement of in vivo electrical activity across the gastroduodenal junction and provide qualitative and quantitative definitions of slow wave activity. The pylorus is a clinical target for a range of gastrointestinal motility disorders and this work may inform diagnostic and treatment practices.

Real-time implementation and explainable AI analysis of delayless CNN-based selective fixed-filter active noise control

The selective fixed-filter active noise control (SFANC) approach can select suitable pre-trained control filters for different types of noise. With the learning ability of convolutional neural network (CNN), the CNN-based SFANC method can automatically learn its parameters from noise data. Combining practical experience, this paper abstracts ANC as a Markov progress and provides a detailed theoretical analysis to verify the reasonableness of the CNN-based SFANC method. To validate its effectiveness, we implement the method in a multichannel ANC window, where the CNN operating in the co-processor collaborates with the real-time controller to realize delayless noise control. Additionally, an explainable AI technique is used to analyze the underlying principle of the CNN-based SFANC method, enhancing its interpretability in acoustic applications. Numerical simulations and real-time experiments demonstrate that the CNN-based SFANC method achieves not only satisfactory noise reduction performance for broadband and real-world noises but also excellent transferability.11The code will be accessible at https://github.com/Luo-Zhengding/SFANC-Window.

Estimation of phase distortions of the photoplethysmographic signal in digital IIR filtering

Pre-processing of the photoplethysmography (PPG) signal plays an important role in the analysis of the pulse wave signal. The task of pre-processing is to remove noise from the PPG signal, as well as to transmit the signal without any distortions for further analysis. The integrity of the pulse waveform is essential since many cardiovascular parameters are calculated from it using morphological analysis. Digital filters with infinite impulse response (IIR) are widely used in the processing of PPG signals. However, such filters tend to change the pulse waveform. The aim of this work is to quantify the PPG signal distortions that occur during IIR filtering in order to select a most suitable filter and its parameters. To do this, we collected raw finger PPG signals from 20 healthy volunteers and processed them by 5 main digital IIR filters (Butterworth, Bessel, Elliptic, Chebyshev type I and type II) with varying parameters. The upper cutoff frequency varied from 2 to 10 Hz and the filter order—from 2nd to 6th. To assess distortions of the pulse waveform, we used the following indices: skewness signal quality index (SSQI), reflection index (RI) and ejection time compensated (ETc). It was found that a decrease in the upper cutoff frequency leads to damping of the dicrotic notch and a phase shift of the pulse wave signal. The minimal distortions of a PPG signal are observed when using Butterworth, Bessel and Elliptic filters of the 2nd order. Therefore, we can recommend these filters for use in applications aimed at morphological analysis of finger PPG waveforms of healthy subjects.

CO2 Storage Site Analysis, Screening, and Resource Estimation for Cenozoic Offshore Reservoirs in the Central Gulf of Mexico

The storage potential of hydrocarbon reservoirs in the central Gulf of Mexico (GOM) makes future development of CO2 storage projects in those areas promising for secure, large-scale, and long-term storage purposes. Focusing on the producing and depleted hydrocarbon fields in the continental slope of the central GOM, this paper analyzed, assessed, and screened the producing sands and evaluated their CO2 storage potential. A live interactive CO2 storage site screening system was built in the SAS® Viya system with a broad range of screening criteria combined from published studies. This offers the users a real-time assessment of the storage sites and enables them to adjust the filters and visualize the results to determine the most suitable filter range. The CO2 storage resources of the sands were estimated using a volumetric equation and the correlation developed by the National Energy Technology Laboratory (NETL). The results of this study indicate that 1.05 gigatons of CO2 storage resources are available in the developed reservoirs at the upper slope area of the central GOM. The Mississippi Canyon and Green Canyon protraction areas contain the fields with the largest storage resources.

Simultaneous film temperature and film thickness measurements for jet impingement applications using two-color laser-induced fluorescence

The study investigates a jet impingement cooling process of a cylindrical geometry relevant for electric and electronic applications. The applied two-color detection technique enables a simultaneous determination of film temperature and film thickness. For this purpose, the heat transfer oil Marlotherm LH was doped with the temperature-sensitive fluorescence tracer nile red. The temperature determination was realized by suitable band pass filters. Preliminary spectral investigations were carried out in terms of varying dye concentration, temperature and film thickness. At high dye concentrations (up to 37.5 mg/L), reabsorption effects lead to a spectral shift toward higher wavelengths with increasing film thickness. Low dye concentrations (0.29 mg/L, 0.59 mg/L) show no film thickness dependent spectral shift. A film temperature investigation at low dye concentration showed no bias of the intensity ratio due to film thickness, i.e., no additional spectral shift toward lower wavelengths was observed. The investigations on the jet impingement setup revealed an increasing film temperature and decreasing film thickness with increasing solid temperature. The average film temperature increases with increasing solid temperature from 298 (solid temperature 298 K) to 308 K (solid temperature 398 K). At higher solid temperatures, the film temperature increases with distance to the stagnation zone. The average film thickness decreases with increasing solid temperature from 0.24 to 0.17 mm. At high solid temperatures, the film temperature increased with radial distance to the stagnation zone. This behavior is caused by the increasing temperature gradient with increasing solid temperature and decreasing viscosity with increasing film temperature.

High yield sterile filtration process for highly concentrated lentiviral vectors.

The development and manufacture of biopharmaceuticals are subject to strict regulations that specify the required minimum quality of the products. A key measure to meet these quality requirements is the integration of a sterile filtration step into the commercial manufacturing process. Whereas common procedures for most biologics exist, this is challenging for lentiviral vector (LVV) production for ex vivo gene therapy. LVVs nominal size is more than half the pore size (0.2µm) of filters used for sterile filtration. Hence, highly concentrated virus solutions are prone to filter clogging if aggregation of viruses occurs or impurities attach to the viruses. Several filters were screened aiming to identify those which allow filtering highly concentrated stocks of LVVs of up to 1E+9 transducing unitsmL-1 , which corresponds to 4.5E+12 particlesmL-1 . In addition, the effect of endonuclease treatment upstream of the purification process on filter performance was studied. In summary, three suitable filters were identified in a small-scale study (<15mL) with virus yields >80% and the process was successfully scaled-up to a final scale of 100mL LVV stock solution.

Suitability analysis of optical filters for enhancing performance parameters in a QPSK CO-OFDM modulation system

Abstract Optical filtering affects the fiber impairments in a fiber optic transmission system and its overall efficiency. The fiber impairments like attenuation, dispersion, and nonlinearities are challenges to overcome. The optical orthogonal frequency division multiplexing (O-OFDM) modulation is among the techniques to overcome these challenges. This paper uses O-OFDM with coherent transmission (denoted as CO-OFDM) and quadrature phase shift keying (QPSK) for modulating subcarriers. It is denoted as QPSK CO-OFDM modulation. This QPSK CO-OFDM (denoted here as QC) modulation system is further modified by introducing different optical filters in its fiber optic link. Different variants of QC are created by using optical filters in its fiber link. For example, the QC_BL is the variant having an optical Bessel filter in its fiber link. Performances of each variant have been evaluated and compared in terms of BER. This comparison allows us to select a suitable filter for a particular parameter, such as dispersion, fiber length, input power, etc. The QC variant having no filter is denoted as QC_WF and is taken as a reference for comparison.