Filter Elements Research Articles

Family of single‐phase high‐frequency isolated AC–AC converters

AbstractThis work presents a family of single‐phase ac–ac converters with high‐frequency isolation based on the association of interleaved transformers and the dual active bridge (DAB) converter. From distinct configurations of the dc link in terms of half‐bridge (HB), full‐bridge (FB), and interleaved full‐bridge (IFB) arrangements, one can obtain three symmetrical and six asymmetrical structures, with distinct trade‐offs among the number of active switches, total dc‐link voltage, and effective operating frequency of the filter elements. Prominent advantages of the derived circuits include input power factor correction (PFC), a nearly sinusoidal load voltage, the operation of active switches under soft‐switching condition during part of the line period, reduced current stresses, good current sharing due to the interleaved transformers, as well as multilevel voltage waveforms on both sides of the high‐frequency transformer (HFT). Experimental results obtained from an experimental prototype of an ac–ac FB‐IFB converter are presented to validate the theoretical assumptions.

High Step Up Converter with Transformerless Inverter for Grid Integration

Objectives: The objective of this paper is to design a high step up converter for PV applications. The output of the converter is applied to an inverter with less number of component counts. Methods: Coupled inductor is proposed in power electronic converters to increase high gain. The output of the dc-dc converter is given to the inverter. Finding: Simulation and hardware results show that the voltage stress in the passive components and the switches is reduced. Highly stable output voltage is obtained in the output due to high step up conversion. The converter can be operated in high step up mode without reaching the extreme limits. The leakage occurring in the coupled inductor is utilized and the problem due to reverse recovery voltage across the diode is reduced. Since low voltage is applied to MOSFET, conduction losses are less with higher efficiency. The inverter has a simple structure and operates at grid frequency. The inverter developed has low THD, better output waveform and the filter elements are of small size. The electromagnetic interference of the proposed inverter is very less. Novelty: The proposed inverter is designed with less number of switches. The proposed topology is simulated and the hardware is developed to know the feasibility of the converter. Keywords: photovoltaic cell; harmonics; high step up converter; multilevel inverter; transformerless

Virucidal properties of new multifunctional fibrous N-halamine-immobilized styrene-divinylbenzene copolymers

Virucidal properties of N-chlorosulfonamides immobilized on fibrous styrene-divinylbenzene copolymers have been studied. Corresponding materials with different functional group structures and chlorine content have been synthesized on FIBAN polymer carriers in the form of staple fibers and non-woven fabrics. The study has been conducted in general accordance with EN 14476 standard on poliovirus type-1 and adenovirus type-5. It has been found that all tested samples exhibit pronounced virucidal activity: regardless of the carrier polymer form, sodium N-chlorosulfonamides inactivated both viruses in less than 30 s, and N,N-dichlorosulfonamides—in 30–60 s. The main mechanism of action of these materials, obviously, consists in the emission of active chlorine from the functional group into the treated medium under the action of the amino groups of virus fragments and cell culture. Considering the previously described antimicrobial and reparative properties of such materials, as well as their satisfactory physical and mechanical properties, the synthesized polymers are promising for the creation of medical devices with increased resistance to microbial contamination, such as protective masks, filter elements, long-acting wound dressings, and others.

Metagenomics analysis of antibiotic resistance genes, the bacterial community and virulence factor genes of fouled filters and effluents from household water purifiers in drinking water

The aim of this study was to explore the influence and removal of household water purifiers (HWPs) on emerging contaminants in drinking water, and their distribution characteristics. The antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), virulence factor genes (VFGs) and bacterial communities were profiled in the fouled filters, influents, and effluents from HWPs with five steps of filtration after 150 days operation, using metagenomics. The results showed that the diversity of dominant species in Poly Propylene 1 μm (PP1) and nanofiltration membrane (NM) was significantly higher than that in other filters. Post-activated carbon (AC) was used to detect low species richness or diversity, and the highest proportion of dominant species, which contributes to the greater microbial risk of HWPs effluents in drinking water. The number of dominant bacterial genera in the filters disinfected with chloramine was higher than that in the same group disinfected with chlorine. The bacterial species richness or diversity in water was reduced by the purification of HWPs because the filter elements effectively trapped a variety of microorganisms. The relative abundance of Antibiotic efflux in the effluents of chlorinated and chloraminated HWPs was 5.58 × 10−3 and 4.60 × 10−3, respectively, which was the main resistance mechanism. High abundance of VFGs was found in HWPs effluents and the relative abundance of aggressive VFGs was significantly higher than those of defensive VFGs. Based on the co-occurrence results, 243 subtypes of ARGs co-occurred with VFGs, and a variety of bacteria were thought to be possible ARGs hosts, which indicated that the host bacteria of VFGs in HWP effluents had a stronger attack ability. The effluent of HWPs with only filtration processes is exposed to the risk of ARGs and VFGs. This study helps to understand the actual purification effect of HWPs and provides a theoretical reference for the management and control of ARGs pollution in domestic drinking water.

Process optimisation of controlled and continuous MgH2 hydrolysis to produce hydrogen

Hydrogen (H2) is an excellent energy carrier with advantages of high energy density, high combustibility, zero pollutant emissions, etc. Magnesium hydride (MgH2) is considered a good candidate for hydrogen storage because of its high hydrogen storage capacity. In this work, a hydrolysis reactor with a filter element was employed, enabling the MgH2 hydrolysis kinetics to improve and occur in a controllable and continuous manner. Specifically, the hydrolysis kinetics can be improved by adjusting the flow rate of the hydrolysis solution and adding additives such as graphite, aluminum sulfate, solid citric acid, etc. Optimising the equipment structure can reduce the MgH2 loss during the hydrolysis process. On this basis, using an improved filter element can achieve controllable and continuous MgH2 hydrolysis, resulting in stable hydrogen production for 12 h at a flow rate of 200–300 mL/min. The results obtained in this study provide a reference for the use of MgH2 to achieve controllable continuous hydrogen production in the field of fuel cells.

Performance optimization of electret air filter

With the rapid development of the society, the severe haze weather caused by particulate matters (PMs) occurs frequently. Electret air filters have been playing an important role in purifying the air and alleviating the pollution. In this work, electret air filters were fabricated based on the polypropylene (PP) materials to investigate their filtering performance to the PMs. First, the electret performance of the PP-based films was mainly focused on. The charge storage stability of the electret films was found to be associated with the material recipe and the electret technique. Introducing 1% of tourmaline into the isotactic PP can realize the best charge storage stability, while adding the graphene can weaken the charge stability. And the electret techniques including the high-temperature pre-aging and polarization at elevated temperature were adopted to optimize the charge storage performance. Then, based on the optimized electret materials and electret technique, the purification performance of the electret filter elements dependent on the polarization condition was evaluated. The present work can provide an optimization strategy to improve the performance of electret materials and electret air filters.

ОБЕСПЕЧЕНИЕ ТЕХНОСФЕРНОЙ БЕЗОПАСНОСТИ ПРИ ПРОИЗВОДСТВЕ ЭМУЛЬСИОННЫХ КАУЧУКОВ

Synthetic polymer materials are in high demand due to their exceptional properties. Their main consumers are the tire and rubber industries. When producing synthetic rubbers, there is a loss of polymer in the form of fine crumb rubber, which is formed at the final stage of their production. Today, the removal of this crumb from the wastewater of latex rubber extraction plants is an urgent issue. The results of a study on the extraction of fine rubber crumbs are presented. The task is solved by using an apparatus for separating water phases in the technology, which allows more complete and rational use of expensive products of chemical and petrochemical production, increase productivity and environmental friendliness of production, which leads to an increase in technosphere safety in general. The optimal flow rates of aqueous phases passed through the spiral belt of the filter element, which is 15–25 m/s, have been determined. The separated water stream containing concentrated fine rubber crumb is returned to the styrene-butadiene latex coagulation stage. The purified water phase after the filter element is collected in a separate collector and used to prepare solutions of coagulating and acidifying agents. The additional introduction of finely dispersed rubber crumbs into the composition of the resulting coagulum do not lead to a deterioration in the basic physical and mechanical properties of the resulting rubbers and vulcanizates. The proposed method for industrial wastewater treatment improves safety in the technosphere.

Methods of Assessing the Effectiveness of Filter Elements in Power Electronics

Newly constructed devices must meet a number of requirements in terms of the level of generated disturbances. To achieve an acceptable level in such devices, filters are installed—one of the cheapest ways to reduce interference in devices. One of the key elements of the filter that is responsible for the effectiveness of noise reduction are ferrites. Unfortunately, for various devices, an individual approach should be used in the selection of filters and, accordingly, ferrites. Due to the fact that ferrites from different manufacturers do not have standardized characteristics and information on their effectiveness, the selection of the right ferrite is a very time-consuming process. Therefore, this article will present the possibilities of quickly determining selected ferrite parameters in order to ensure the necessary level of noise reduction. For this purpose, assumptions from the CISPR 17 standard will be used. For selected types of ferrites, a large number of measurements were carried out in order to determine the optimal computational algorithm for adjusting ferrite characteristics to the designed conditions. The performance of these tests will be the basis for conducting tests on a larger number of ferrites, as well as for the development of possible standardization procedures.

Demonstration of the model of physicochemical processes in heavy liquid metal cooled reactors in an example of the THEADES experiment simulation

Activities have been currently underway across the world to build heavy liquid metal-cooled reactors. Thus, for example, the ALFRED and BREST-OD-300 reactor designs use lead coolant, while the MYRRHA and CLEAR-I reactors use lead–bismuth coolant. The high corrosive and erosive activity of the coolant requires regulations oxygen concentration (1 ÷ 4E-6 wt.%) and flow velocity (0.5 ÷ 2.5 m/s). Due to the complex geometry of the reactor circulation circuit flow paths, numerical simulation methods are used extensively to justify scheduled modes of operation for liquid metal coolants. Correct justification of the complex oxygen transport processes in liquid metals requires the respective physicochemical computation model, which takes into account the main reactions of oxygen with the coolant and the structural materials.This paper presents a physicochemical model, which includes the following processes: erosion, growth, and dissolution of the two-layer oxide film, coagulation and dissolution of metal oxides in the circuit with subsequent deposition on filtering elements, and inflow from mass transfer apparatuses. StarCCM+, a commercial CFD code, was used as the tool in this study. The physicochemical model was implemented using models of passive impurities, which are used to simulate oxygen transport in the circulation circuit.Capabilities of the presented model were demonstrated based on the results of investigating thermohydraulic and physicochemical processes obtained at the THEADES experimental facility. The duration of the simulation was 1000 h.The distributions of impurity concentrations, increased erosive activity areas, as well as the total amount of oxides deposited on filter and the amount of oxygen entering the circuit have been obtained as a result of the calculations. The surface distribution of the oxide film thickness on the test facility surfaces contacting the coolant has also been calculated. These data can be extrapolated to reactor elements that operate under conditions that are similar to the considered experiment. For example, fuel assemblies.Simulation of thermocouples, as well as taking into account manufacturing technology made it possible to improve the accuracy of calculating the flow’s thermohydraulic characteristics as compared to earlier studies.

Determination of the input filter parameters of the active rectifier with a fixed modulation frequency

Goal. Development of a methodology for calculating the parameters of the active rectifier-voltage source input filter operating with a fixed modulation frequency to ensure electromagnetic compatibility with the supply network acceptable by standards at minimum values of the input inductance and checking its main characteristics on a mathematical model. Methodology. The authors have developed a methodology for calculating the parameters of the input filter of an active rectifier-voltage source. The calculation results are verified on the constructed mathematical model of a frequency converter, the scheme of which is an active rectifier and an autonomous voltage inverter. A series of experiments was carried out on a mathematical model to study the dependence of the total harmonic distortion of current and mains voltage on the value of the input inductance for various parameters of the input filter. Results. The structure and calculation procedure the input filter of an active rectifier operating with a fixed modulation frequency are proposed. The simulation results showed that the inclusion of a filter at the input of the active rectifier significantly improves its electromagnetic compatibility with the supply network in the entire range of variation of the input inductance of the circuit and makes it possible to achieve the values of the total harmonic distortion permissible by the norms. Originality. A structure and a calculation procedure the input filter of an active rectifier-voltage source operating with a fixed modulation frequency are proposed. Practical significance. The dependencies obtained in the article allow us to evaluate the relationship between the parameters of the filter elements and its characteristics among themselves and come to a compromise between them when designing a scheme for specific technical conditions.

A voltage type single-stage multi-input distributed generation system

To solve the problems of unstable and discontinuous power supply resulted by single input power generation, like photovoltaic(PV) and wind energy changing with climatic conditions, it's significant to research multiple new energy combined power generation systems. A voltage type single-stage multi-input distributed generation system(PGS) is proposed and studied in this paper. The system's circuit topology, control strategy and derivation of multiple duty cycles are researched thoroughly. This system consists of multiple input sources and their corresponding filter capacitors, parallel time-sharing selector switches, inverter bridge, output filter element and line-frequency(LF) transformers. In the control strategy, the maximum power point tracking (MPPT) is used in the outer loop, and grid-connected current (GCC) tracking is used in the inner loop. The duty cycle of each power source is deduced under this control strategy. The problems of voltage spike and DC bias are solved. A 3kW experimental prototype is designed, and the results are favorable, which proves that the system has practical significance.

Design and Simulation Analysis of the Folding DPF for Agricultural Diesel

According to the demand of diesel particulate filter (DPF) for agricultural machinery diesel, a folding DPF was designed by using metal fiber felt as filter element material. The flow characteristics in the designed DPF are simulated by CFD software Fluent, to optimize the structural parameters of the folding DPF. The results show that the pressure drop increases obviously when the ratio of filter element height to inlet height greater than 2; When keeping the filtering area unchanged, the pressure drops of odd filter layers 5, 7 are smaller than that of even filter layers 4, 6, 8, which can be reduced up to 14%; Increasing the length of the filter element helps to make the velocity distribution more uniform along the radial direction at the rear end of the DPF.

Разработка системы мониторинга сетевого трафика с элементами фильтрации на уровне L2

This article proposes a network traffic monitoring system with filtering elements at the data link layer (L2) of the OSI model. This article presents the general requirements and approaches to the construction of the proposed monitoring and filtering system. The developed device is built on the basis of SDN technology, which makes it possible to create a more flexible and multifunctional network device compared to traditional network devices. In the process of developing the device, standard methods and components available to the masses were used. Under the conditions of the tasks set, a schematic diagram of the developed device based on the TE0714 TRM model board and the SFP standard transceiver is presented. It is proposed to use the device for a monitoring system with filtering elements. Network traffic monitoring is proposed to be implemented based on the SNMP protocol to collect information from critical network nodes. It is proposed to implement network traffic filtering based on a "white" list of MAC addresses to limit the list of devices that have access to the system. The practical significance of this article lies in the description of the approach to the development of a fundamental device for monitoring public and personal networks with flexibly defined additional and basic functions. The proposed device, thanks to the use of SDN technology, provides individual customization for customer requests, which means the possibility of expanding functionality without purchasing new hardware and firmware. The proposed device, due to the use of SDN technology, provides individual customization for customer requests, which means the possibility of expanding the functionality without purchasing new hardware and firmware.

Peculiarities of the Norton conversions application when matching impedances with different transformation coefficients

The paper studies the features and consequences of the use of Norton conversions in the process of broadband and narrowband matching of circuit impedances based on filter theory in cases with different transformation ratios. For Norton circuits conversions with different transformation ratios (greater than and less than one), an additional rule is formulated. Using the generalized form of recording the Norton consequence conversions, two examples of reducing the number of elements in bandpass filters are demonstrated. In addition, the consequences that are characteristic of narrow-band applications of transformations are established. Formulas for calculating transformation ratios that depend on frequency are obtained for direct and mirror Г-shaped circuits with different reactivities. It is shown that these circuits can be combined with similar reactivities of Г-shaped circuits with frequency independent transformation ratios. On the basis of the established for the Norton conversions consequences, the step-up and step-down matching circuits of the combined type are synthesized.

Development of carbon based composites for filtering elements used on bilge's oily water treatment units

Due to complicated ingredients contained within bilge's oily water on board ships, efficient separations as per the relevant standard cannot be easily handled while considering the cost and performance of the filter elements currently used. In this research, activated carbon and expanded natural graphite (ENG) were employed to synthesize the composite adsorbent for adsorption of the emulsified oil. Orthogonal experiments were designed to determine the processing parameters for synthesizing activated carbon from potassium hydrate and phenolic resin, composite adsorbents were prepared by mixing ENG with different mass ratios and densified to a density comparable to that of the commercially available filtering material. Comparisons between the composite and filtering materials were made in terms of structure, morphology, adsorption equilibrium as well as the strength and stability under typical loads and impacts. It showed that the activated carbon sample prepared by the impregnation ratio, heating temperature and heating duration respectively about 4:1, 650 °C and 2 h had a better adsorptive performance. It also revealed that, within 298.15 K–308.15 K, in comparing with those on the commercially available filtering material, the AE-10 sample prepared by mixing 10 wt% ENG and densified to 0.03 g cm−3 had 270% increment in adsorption amount of the emulsified oil and one seventh deformation in size as well as one tenth mass loss in weight, respectively. It suggests that the composite formed by ENG and the activated carbon sample having larger specific mesopore volume and surface area are promising for the treatment of onboard oily water.

Testing and Performance Evaluation of Water Pump Irrigation System using Voltage-Lift Multilevel Inverter

The positive or negative output voltage-lift technique is intended to provide a preferable contribution to energy conversion. This topology is modified from two configurations such as super- lift and voltage-lifting technique. The proposed model introduces the progress of symmetric Voltage- Lift Inverter (VLI) technique in which the semiconductor switches are reduced compared to the conventional or modified type of Multilevel Inverter (MLI). From a research point of view, the parameters are analyzed in-field program gate array. It comprises of Particle Swarm Optimization (PSO) rules to help maximizing the system voltage with aid of Maximum Power Point (MPP) tracking in PV fed inverter for water pumping applications. The performance factors under different PV irradiation conditions are analyzed using MATLAB/Simulink and Hardware based results. Solar-Photovoltaic (S-PV) modules are fed to the proposed inverter, which is then connected in series with the combination of a submersible water pump. It will enhance power by MPP approach for symmetric inverter technology which is performed with the necessary voltage conversion applied in water pump irrigation used for agriculture specific areas. In this method, voltage-lift inverter is capable of testing and evaluated with desired output level necessary power conversion to solar water pump method. Results are representing to save the fuel and electricity cost with the help of solar fed water pump using Induction Motor (Im) load. The minimum harmonics from simulation and hardware circuit is achieved by variation of optimum pulses given into converter switches. Due to the reduced bulky semiconductor devices and filter element it anticipates the improved efficiency for the proposed inverter system.

CompositeView: A Network-Based Visualization Tool.

Large networks are quintessential to bioinformatics, knowledge graphs, social network analysis, and graph-based learning. CompositeView is a Python-based open-source application that improves interactive complex network visualization and extraction of actionable insight. CompositeView utilizes specifically formatted input data to calculate composite scores and display them using the Cytoscape component of Dash. Composite scores are defined representations of smaller sets of conceptually similar data that, when combined, generate a single score to reduce information overload. Visualized interactive results are user-refined via filtering elements such as node value and edge weight sliders and graph manipulation options (e.g., node color and layout spread). The primary difference between CompositeView and other network visualization tools is its ability to auto-calculate and auto-update composite scores as the user interactively filters or aggregates data. CompositeView was developed to visualize network relevance rankings, but it performs well with non-network data. Three disparate CompositeView use cases are shown: relevance rankings from SemNet 2.0, an open-source knowledge graph relationship ranking software for biomedical literature-based discovery; Human Development Index (HDI) data; and the Framingham cardiovascular study. CompositeView was stress tested to construct reference benchmarks that define breadth and size of data effectively visualized. Finally, CompositeView is compared to Excel, Tableau, Cytoscape, neo4j, NodeXL, and Gephi.

Single-Phase Isolated AC-AC Converters Based on the Dual Active Bridge Converter

This article presents three single-phase isolated ac–ac converters based on the dual active bridge (DAB) converter and interleaved transformers. The structures allow obtaining filter elements with reduced dimensions, as well as bidirectional power flow and high efficiency over a wide load range. Multilevel voltage waveforms exist in the input and output sides of the symmetrical converters, resulting in reduced harmonic content. The possible arrangements include a symmetrical half-bridge converter (SHBC), a symmetrical full-bridge converter (SFBC), and a symmetrical interleaved full-bridge converter (SIFBC). The introduced topologies can be regarded as prominent solutions for applications involving solid-state transformers, dynamic voltage restorers, and uninterruptible power supplies. A thorough mathematical analysis of the SHBC is carried out and experimental results are presented to investigate the converter performance in steady-state and transient conditions.

Wire weaving for all applications

Metal woven wire cloth is used everywhere in industry, research, the building trade and many aspects of everyday life, from flow filters in water taps to precision filter elements in space craft. Haver & Boecker explains how woven wire cloth fulfils a variety of requirements and is fundamental to the areas of application.

A Novel Air Filter Element from Wood Fiber Capable of Improving Engine Performance — Parameters Optimization and Experimental investigation

A Novel Air Filter Element from Wood Fiber Capable of Improving Engine Performance — Parameters Optimization and Experimental investigation