Filter Components Research Articles

Optimal design of single-tuned filters for industrial power systems to reduce harmonic distortion using forest algorithm

ABSTRACT This paper presents a novel optimization algorithm for designing single-tuned filters in industrial power systems to reduce harmonic distortion. Single-tuned filters are cost-efficient, simple, and easy to maintain. We formulate the filter design as an optimization problem, minimizing costs while incorporating harmonic limits and system constraints. Our solution algorithm simulates tree growth, proliferation, and death based on the forest algorithm to generate optimal solutions. This enables both local and global searches for fast convergence and feasible designs. Unlike traditional approaches, we account for variations in filter components and system parameters caused by factors like manufacturing tolerances, operating temperature, and frequency variations. Our study contributes by designing adaptive filters that match practical systems. We validate our method against previous publications and other techniques like simulated annealing and teaching-learning-based optimization. Simulation results demonstrate the effectiveness of our approach in minimizing costs, satisfying operation constraints, and accounting for component variations in this complex problem.

The Role of Attention in Category Representation.

Numerous studies have found that selective attention affects category learning. However, previous research did not distinguish between the contribution of focusing and filtering components of selective attention. This study addresses this issue by examining how components of selective attention affect category representation. Participants first learned a rule-plus-similarity category structure, and then were presented with category priming followed by categorization and recognition tests. Additionally, to evaluate the involvement of focusing and filtering, we fit models with different attentional mechanisms to the data. In Experiment 1, participants received rule-based category training, with specific emphasis on a single deterministic feature (D feature). Experiment 2 added a recognition test to examine participants' memory for features. Both experiments indicated that participants categorized items based solely on the D feature, showed greater memory for the D feature, were primed exclusively by the D feature without interference from probabilistic features (P features), and were better fit by models with focusing and at least one type of filtering mechanism. The results indicated that selective attention distorted category representation by highlighting the D feature and attenuating P features. To examine whether the distorted representation was specific to rule-based training, Experiment 3 introduced training, emphasizing all features. Under such training, participants were no longer primed by the D feature, they remembered all features well, and they were better fit by the model assuming only focusing but no filtering process. The results coupled with modeling provide novel evidence that while both focusing and filtering contribute to category representation, filtering can also result in representational distortion.

Enhancing Preamplifier Design for Acoustic Emission Detection Instrument

With the development of the industry, the safety of pressure vessels is crucial for both production and personnel safety. The application of acoustic emission testing technology as a dynamic non-destructive testing method in the detection of pressure vessels is becoming increasingly prevalent. This paper presents the design of a low-frequency acoustic emission preamplifier with a frequency range of 30KHz to 200KHz and a gain of 20dB. The preamplifier is composed of amplification circuits, power supply circuits, and filtering components. By utilizing the PXR04 series high-sensitivity resonant acoustic emission sensor and Texas Instruments' OPA333 operational amplifier, along with a clever power supply design, effective signal amplification and system stability are ensured. Experimental results validate the correctness of the design, providing a feasible and effective solution for enhancing the performance of acoustic emission testing equipment.

Research on enhancing separation of ultra‐fine droplets using turbulators between adjacent demister plates in WFGD systems

AbstractTo enhance the performance of demister applied in wet flue gas desulphurization systems, flow turbulators are equipped between adjacent plates to reconstruct flow field. Both experimental and numerical approaches are employed to investigate the influence of various kinds of turbulator configurations upon removal of droplets within the range of 5–50 μm obeying Rosin‐Rammler distribution. Turbulators including spoiler, square column, concave groove, perforated concave groove, and triangular and cylinder columns are compared, among which spoiler provided the highest overall efficiency while square column yields the best graded efficiency for 5 μm droplets group. Furthermore, moving the spoiler towards the core region of the demister ducts received better performance due to augmented interaction between spoiler and drainage channels, which performed an essential role in droplets collection. Based on this knowledge, spoilers are optimized by changing their angle of attack and size; the result is positive since overall separation efficiency can be improved to 100%, along with graded efficiencies for 10 and 5 μm groups achieving 95.97% and 27.26%, respectively, much higher than those of baseline demister without turbulators. This study indicates that inertial‐based demisters have great potential in separating ultra‐fine droplets through reorganizing turbulence field, thus extra system loss can be avoided by abandoning additional filter components.

Advanced visual components inspired by animal eyes.

Artificial vision systems pervade our daily lives as a foremost sensing apparatus in various digital technologies, from smartphones to autonomous cars and robotics. The broad range of applications for conventional vision systems requires facile adaptation under extreme and dynamic visual environments. However, these current needs have complicated individual visual components for high-quality image acquisition and processing, which indeed leads to a decline in efficiency in the overall system. Here, we review recent advancements in visual components for high-performance visual processing based on strategies of biological eyes that execute diverse imaging functionalities and sophisticated visual processes with simple and concise ocular structures. This review first covers the structures and functions of biological eyes (i.e., single-lens eyes and compound eyes), which contain micro-optic components and nanophotonic structures. After that, we focus on their inspirations in imaging optics/photonics, light-trapping and filtering components, and retinomorphic devices. We discuss the remaining challenges and notable biological structures waiting to be implemented.

Impact of adaptive filtering-based component analysis method on steady-state visual evoked potential based brain computer interface systems

<span lang="EN-US">The significance of brain computer interface (BCI) systems is immensely high, especially for disabled people and patients with nervous system failure. Therefore, in this study, adaptive filtering-based component analysis (AFCA) model is presented to enhance target box identification efficiency at varied flickering frequencies in a visual stimulation process by efficient acquisition of electroencephalogram (EEG) signals for the application of steady-state visually evoked potential based BCI system. Furthermore, optimization of proposed AFCA model is performed based on the maximized reproducibility of correlated components. A multimedia authoring and management using your eyes and mind (MAMEM) steady-state visual evoked potential (SSVEP) dataset is utilized for efficient training of EEG signals and background entities are eliminated using adaptive filters in a pre-processing stage. Additionally, spatial filtering components are obtained to detect target flickering box based on the obtained quality features. Performance is measured by acquisition of SSVEP signals in terms of reconstruction efficiency, classification accuracy and information transfer rate (ITR) using proposed AFCA model. Mean classification accuracy for all 11 subject is 93.48% and ITR is 308.23 bpm. Further, classification accuracy is relatively higher than various SSVEP classification algorithms.</span>

Analysis of AC filter detuning characteristics and improvement measures in converter station

Shift of parameters of the double-tuned AC filter component and failure in prompt correction of detuning frequency may affect the filtering effect of the AC filter. Therefore, this paper studies impedance-frequency characteristics of the double-tuned AC filter according to detuned recording data of the A-typed double-tuned AC filter in the Congxi converter station. It analyzes the variation of the impedance-frequency characteristic curves and relative change rate of resonant frequency as there are deviations between actual values and rated values of each filter capacitance and inductance elements in different degrees, and concludes that variation of the parameter of each element in different degrees may cause different deviations of resonant points of the double-tuned AC filter. MATLAB simulation has proved it can reduce the detuning degree and improve the filtering performance of the filter by adjusting the parameters of the variable reactor to change in the opposite direction of the parameters of the resonant capacitor.

LCL Trap Filter Analysis with a PFC Isolated Ćuk Converter Using SiC MOSFET for DCM

The main contribution of the paper concerns the use of an LCL trap filter with a PFC isolated Ćuk converter. Further, SiC MOSFET is used with a PFC isolated Ćuk converter designed for 50 W with 42 kHz in DCM. A small-signal model of the converter is cascaded with the filter model to investigate the effect of the filter on the whole system. Moreover, large-signal and small-signal models of the converter are compared to investigate the requirement of the small-signal analysis. In addition, an LTspice simulation using SiC MOSFET of the system is conducted and the results are compared by the applications for both LC and LCL trap filters with respect to different loading conditions. Further, the LCL trap filter is compared with the LC filter regarding the PF, THD, and efficiency. Controller design considering the filter is also presented. In addition, the converter is operated and compared using linear and nonlinear loads for each filter. Parametric variation in the filter components is investigated. As a result of the simulation and applications, the THD of the grid current is 4.83% and the PF is 0.998, meeting the standards, and the overall efficiency of the system is 85% with the LCL trap filter. It can be concluded that the presented filter provides better results than the LC filter.

Comparison of the effect of output filters on the total harmonic distortion of line current in voltage source line converter - simulation study.

Two different output filter topologies are considered, namely the LCL- and L+LC-filter. The space vector modulation (SVM) is used to control the power switches of the converter. Design methods for both filter types are proposed. The methods are used to dimension the filter components. The performances of the filters designed are verified by simulations to meet the given line current total harmonic distortion (THD) requirement. The study reveals that the LCL-filter is more effective a filter topology in attenuating line current harmonic components than the L+LC-filter.

On-chip passive pump-rejection long-pass filters for integrated SiC-based nonlinear and quantum photonic chips

We present an on-chip passive pump-rejection filter on an integrated silicon carbide (SiC)-on-insulator photonic platform. Our filters exploit the optical absorption from an amorphous silicon (α-Si) thin-film layer deposited on the top surface and on the sidewalls of the SiC waveguide to reject light with a wavelength below 1.0 µm. The filter has a simple design and can be readily fabricated using a standard semiconductor wafer fabrication process and can be integrated as a pump-rejection filter component for SiC-based nonlinear and quantum photonic chips. We experimentally demonstrate a pump-rejection efficiency exceeding 230 dB/mm for 780 nm wavelengths, while we extract an insertion loss of ∼1 dB for the O-, C-, and L-bands.

Terahertz tunable band-stop filter using topological valley photonic crystals.

In recent years, there has been a growing interest in the wideband propagation and control of terahertz (THz) radiation due to its potential for a variety of applications, such as 6G communication, sensing, and imaging. One promising approach in this area is the use of valley photonic crystals (VPCs), which exhibit properties like wider band gaps and robust propagation. In this paper, a two-dimensional dielectric silicon-air VPC is studied, which is constructed from a method of inversion symmetry breaking providing a band gap of 109.4GHz at a mid-gap frequency of 0.376THz. We employ an optimized bearded-stack interface to construct the VPC waveguide for wideband THz propagation along straight and Z-shaped paths. We demonstrate that a band-stop response can be achieved in a VPC by introducing periodic defects along the domain wall. Furthermore, the stop range can be tuned by varying the refractive index of the defects through incorporating liquid crystal along the domain wall of VPC. Our proposed structure and the techniques employed could be promising for the development of a band-stop filter (BSF) and other photonic components having potential applications in 6G communication and beyond.

FedAAA-SDN: Federated Authentication, Authorization and Accounting in SDN controllers

Modern technology advancements such as Software Defined Networking (SDN) have been employed in distinct scenarios such as cloud computing and wireless networks, and have made network administration simpler since it gives greater flexibility in centralizing the configurations of a network and its data. Several SDN controllers have started to offer Authorization, Authentication, and Accounting (AAA) services to improve user management and security, including support for OAuth2.0. However, basic authentication schemes using the tuple username and password are not considered secure nowadays (prone to brute force attacks), or the use of basic tokens in OAuth 2.0 is propitious to security vulnerabilities not meeting the security requirements in current and future use cases dealing with authentication. Therefore, the main objective of this work is the design and evaluation of the FedAAA-SDN framework enabling authentication, authorization, and accounting mechanisms in SDN controllers controlling different types of networks. In particular, the FedAAA-SDN framework enables federated authentication and authorization processes for network functions by enabling the conveyance of identity and authentication information across heterogeneous domains/networks, allowing also network operators to enforce authorization policies for network functions in wired and wireless networks. A FedAAA-SDN proof of concept is implemented with OpenDaylight as the SDN controller, OpenID Connect as the authentication and authorization mechanism, and Keycloak as the OpenID Provider. FedAAA-SDN also includes the concept of trust levels and trust policies that rely on the context information of a user’s device and associated connected access networks. The implementation of the FedAAA-SDN framework proof of concept involves modifications in the OpenDaylight AAA filter component to secure all the interactions with the several network applications/subcomponents of the OpenDaylight SDN controller. STRIDE security analysis demonstrates that the FedAAA-SDN framework is able to reduce the number of threats.

Histological observations and gene expression of the digestive system of the Chinses mitten crab (Eriocheirsinensis)

In order to elucidate the structural characteristics and gene expression of the tissues of the digestive system of adult Eriocheir sinensis, this study was conducted to systematically study the digestive system of E. sinensis using histological and transcriptomic techniques. The results showed that the digestive system of E. sinensis mainly consisted of the esophagus, stomach (including cardia stomach and pyloric stomach), midgut, intestinal bulb, hindgut and hepatopancreas. In the cardia stomach, calcification of the cuticle into cuticular ossicles, chitin tooth, ridge, bristles and other structures were observed at different sites, which together form the "Gastric mill" for grinding food. The pyloric stomach contains special comb-like structures and rows of pectinate bristles, which are important components of the gland filter for filtering and sifting food. The wall of the digestive tract of E. sinensis consists of four layers: the mucosal layer, the submucosal layer, the muscular layer and the outer membrane, of which the surface of the mucosal layer of the esophagus and hindgut has a well-developed cuticle with rows of setae, and the submucosal layer has special mucus glands (esophageal glands or hindgut glands); the surface of the mucosal layer of the midgut has no cuticle and has dense microvillus. The intestinal bulb has the morphological characteristics of the transition from midgut to hindgut. The hepatopancreas consists of many hepatic tubules, and four types of cells are often seen in the hepatic tubules, including absorptive cells (R cells), vesicular cells (B cells), fibroblasts (F cells), and embryonic cells (E cells). The transcriptome data of the digestive system of E. sinensis showed that Esophagus, Stomach, Midgut, Intestinal bulb, Hindgut and hepatopancreas expressed 13252, 13285, 13634, 11147, 13127, 12551 genes respectively; and they specifically expressed 1529, 549, 1199, 624,990, 1688 genes respectively. A total of 25 digestive enzyme genes were isolated from six tissues of the digestive system. Except for maltosidase-glucoamylase and phosphatase A2, which had small differences in expression in various tissues of the digestive system, all other digestive enzymes had the highest expression in the hepatopancreas. Digestive enzymes with high expression in the hepatopancreas are trypsin, pancreatic rennin, carboxypeptidase B, ɑ-amylase, and astacin.

STRUCTURE AND PROPERTIES OF THE GLOMERULAR FILTRATION BARRIER OF VERTEBRATES: ROLE OF CHARGE FOR FILTERING PROTEINS

The renal glomerulus is a unique structure that distinguishes the nephrons of vertebrates from the nephridia of invertebrate animals, providing a direct connection between the circulatory and excretory systems and the most effective control of the composition of the internal environment due to the significant intensification of filtration. The modern ideas about the structure of the glomerular filtration barrier in representatives of all major groups of vertebrates (cyclostomes, fishes, amphibians, reptiles and birds, mammals) were reviewed. Emphasis is placed on the role of the charge of the glomerular barrier structures for its selective properties; approaches to studying the contribution of the anionic components of the renal filter to preventing the loss of plasma proteins are described. The main models of the glomerular filter functioning presented in the literature are considered. Negative charge has been demonstrated to be a distinctive feature of the glomerular filter in all vertebrates. It was shown that a multiple increase of the glomerular filtration rate (from lower vertebrates to birds and mammals) was accompanied by a number of structural changes that ensured the passage of a significant volume of water and dissolved low-molecular substances through the glomerular filter: an increase in the number and ordering of fenestrae in the endothelium of glomerular capillaries, thinning of the glomerular basement membrane and complete exclusion of cellular elements from it. It has been shown that comparative physiological data on the glomerular filter in different groups of vertebrates most strongly confirm the electrokinetic model of the glomerular filtration, since it explains the importance of the evolutionarily conservative structure of podocytes and the role of a set of fixed anionic charges in the filter wall to prevent the loss of macromolecules (primarily proteins) from blood at different intensities of the ultrafiltration.

Design Procedure for a High-Efficiency Class-E/F3 Power Amplifier

The switch voltage stress in a Class-E power amplifier (PA) is larger than that in any other switching PAs. A series resonant filter is added across the switch to filter out the third harmonic of the switch voltage and reduce the switch voltage stress. The new circuit is usually called a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA. The output power, the efficiency, and the component values of a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA can be <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sensiti</b> ve to the design of the harmonic filter. In this article, we perform a sensitivity analysis on Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA and provide guideline to design a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA which is robust against variations in the harmonic filter components. We also provide new design equations to calculate the component values. To validate the proposed design guidelines and equations, a prototype circuit was designed and implemented. At <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> = 4.5 V, the measured output power, the efficiency, and the switching frequency of the prototype PA were 0.96 W, 94.2%, and 800 kHz, respectively.

Multi-objective optimization of two-stage AC–DC power supply for reliability and efficiency using NSGA-II and meta-heuristic honey bee algorithms

This paper introduces a novel approach to simultaneously optimize the reliability and efficiency of a switching power supply (SPS) using the Non-dominated Sorting Genetic Algorithm (NSGA-II) and Honey Bee Algorithm (HBA). The proposed method uses a Markov model to evaluate the reliability of the converter and maximizes objective functions, including efficiency and reliability, using optimization algorithms to identify the optimum values of the converter parameters. The optimization algorithm determines the optimal values for converter parameters, such as switching frequency, transformer turn ratio, and DC-link voltage. It also fine-tunes circuit components, such as the power factor correction inductor, DC-link capacitor, and output filter components. A sensitivity analysis is carried out to assess the impact of various parameters on the multi-objective functions of the converter. The converter’s reliability and mean time to failure (MTTF) are evaluated using the Markov reliability model, considering all components’ short and open circuit faults. The failure rates of converter components are calculated using the MIL-HDBK-217 methodology. The results obtained from the NSGA-II and HBA are compared to identify the superior algorithm with the best-optimized parameters. Simulation results indicate that the proposed optimization technique enhances the converter’s reliability performance while maintaining its efficiency. Furthermore, this paper presents comprehensive analyses, comparisons, and experimental findings to demonstrate the converter’s fault-tolerant capability. The multi-objective optimization approach offers a practical and effective strategy for optimizing switching power supplies for efficiency and reliability

Preparation of a High-Performance Asymmetric Supercapacitor by Recycling Aluminum Paper and Filter Components of Heated Tobacco.

In this study, Al paper and cellulose acetate (CA) filters derived from heated tobacco waste were successfully converted into current collectors and active materials for a supercapacitor device. Typically, heated tobacco contains electrically discontinuous Al paper. First, Al was extracted from the tobacco waste using HCl to produce Lewis acid (AlCl3). This acid was then used in an Al electrodeposition process utilizing the chloroaluminate ionic liquid reaction between the acid and the base (RCl) at room temperature. To enhance the conductivity, a supplementary coating of Al metal was applied to the Al paper through electrodeposition, thus re-establishing the electrical continuity of the discontinuous parts and forming an Al-coated current collector. Moreover, the CA filters were carbonized under a nitrogen atmosphere, yielding carbon precursors (C-CA) for the supercapacitor electrodes. To further enhance the electrochemical performance, nickel oxide (NiO) was incorporated into C-CA, resulting in C-CA@NiO with pseudocapacitance. The specific surface area of CA increased with carbonization and the subsequent incorporation of NiO. The as-synthesized C-CA and C-CA@NiO materials were applied to an Al-coated current collector to obtain C-CA- and C-CA@NiO-based electrodes, exhibiting stable electrochemical behavior in the voltage range of -1.0 to 0 V and 0 to 1.0 V, respectively. An asymmetric supercapacitor (ASC) device was assembled with C-CA@NiO and C-CA as the positive and negative electrodes, respectively. This ASC device demonstrated a high specific capacitance of 40.8 F g-1, while widening the operating voltage window to 2.0 V. The high electrochemical performance of the device is attributed to the successful Al electrodeposition, which facilitates the electrical conductivity and increased porosity of the C-CA@NiO and C-CA materials. To the best of our knowledge, this is a pioneering study in regards to the conversion of biomass waste into current collectors and active materials to fabricate a practical ASC device. Our findings highlight the potential of reusing Al paper and CA filters from heated tobacco waste as essential components of energy storage devices.

Eye detection and coarse localization of pupil for video-based eye tracking systems

A video-based eye tracking system generally captures NIR images, each of which contains one or two eyes of a subject. The subject’s point of gaze is then determined using 3D eye model and pupil centre corneal reflection technique. Eye detection and pupil localization play significant roles in video-based eye tracking systems. However, face rotation, wearing glasses, eye-shape variation and illumination variation make it difficult to detect an eye and localize a pupil accurately in the images captured by video-based eye tracking systems. In this paper, we proposed an eye detector that adopts a coarse-to-fine strategy. The eye detector consists of three classifiers: an ATLBP-THACs feature-based cascade classifier, a branch CNN and a multi-task CNN. We also proposed a method for coarse pupil localization. Coarse localization is an important step for pupil localization since it can provide initial pupil coordinates for a fine pupil localization method. Given a downscaled eye image, a shallow CNN is used to estimate the location of seven landmarks. On this basis, pupil center and radius are estimated. A method for small dim target enhancement is used to increase the contrast between pupil and background. The main goal of pupil enhancement is to make it easier to binarize an eye image. At last, component filtering is made by utilizing the estimated pupil center and radius. We collected a dataset named neepuEYE dataset that consists of 5500 NIR eye images from 109 people. The images can be used to generate augmented samples for training an eye detector since they contain eyes with different shape, orientation and pupil localization. Experimental results show that our eye detector is a fast and robust detector. Furthermore, our method for coarse pupil localization can obtain not only high detection rate but also high localization speed.

Identification of combustion parameters from cylinder head vibration signal with the influence of random road excitation

The combustion process feedback information can be extracted from the vibration signals of the cylinder head. This is of positive significance for the online monitoring of combustion status and closed-loop control of combustion processes in internal combustion engines. To obtain the combustion process feedback information under the random road excitation (RRE) condition, this paper firstly simulates and analyses the influence of RRE on the combustion parameters identification by an established simplified diesel-suspension model. Results show that the amplitude, frequency and phase of road excitation signal seriously affect the identification of the combustion characteristics, and the combustion excitation response signal is covered by the road excitation response signal in most cases. Then, a method of combining a high-pass filter and principal component analysis (HPF-PCA) is proposed to extract the combustion parameters. This method effectively eliminates the road excitation response signal and successfully identifies the start of combustion (SOC), the location of maximum pressure rise rate (LMPRR) and the location of peak pressure (LPP) from the processed vibration acceleration signal. Finally, the phase deviation caused by the filtering is corrected based on the relationship between the phase deviation of SOC and the cut-off frequency of filtering. The corrected results show that the maximum deviation between the SOC identified from the vibration signals that with and without the influence of road excitation is 0.8 deg.

Tunable-wavelength broadband spectrum dissipative soliton mode-locked fiber laser

The tunable-wavelength broadband spectrum dissipative soliton (DS) is demonstrated in Yb-doped mode-locked laser using an all-fiber structure saturable absorber (SA), that is, graded index multimode fiber (GIMF)-step index multimode fiber (SIMF)-GIMF with 4.70% modulation depth and 4.55 mW saturation power. Increasing pump power alters intra-cavity balance between loss and gain and nonlinear and dispersion, causing wavelength adjustment and spectrum broadening. The center wavelength shifts towards shorter wavelength with rang of 1037.77–1024.83 nm, corresponding 3-dB bandwidth widens from 6.10 to 9.23 nm and pulse width narrows from 23.80 to 13.38 ps. The signal-to-noise ratio (SNR) is 71.2 dB at the repetition rate of 14.63 MHz. The GIMF-SIMF-GIMF structure has a huge potential to serve as both SA and filter component for the tunable-wavelength broadband spectrum Yb-doped mode-locked fiber laser (MLFL), which is favorable for developing the field of nonlinear microscopy and material processing.