Filter Elements Research Articles

Multi-objective optimization of laser perforated fuel filter parameters based on artificial neural network and genetic algorithm

In precise fuel circuit systems, the filtration of particulate impurities seriously affects the efficiency and service life of various components. For filtration process intensification of high-pressure fuel laser perforated filters, the two-phase flow characteristics in filters is studied. The size, position and number of filtration holes are taken as optimization variables, and take the filtration efficiency and flow pressure drop as optimization objectives. Computational fluid dynamics (CFD) is used to simulate the two-phase motion of continuous phase and discrete particles in a periodic unit. Artificial neural networks (ANN) are utilized for objectives prediction, and the NSGA-II genetic algorithm is employed for multi-objective optimization, resulting in the Pareto front solution set. Furtherly, the reasonable solution is selected by introducing TOPSIS to ensure that two optimization indexes are relatively smaller and balanced. The optimized filter element scheme allows the filter to have a pressure drop of less than 3.2 MPa under high pressure and a filtration efficiency of over 80% for spherical particle impurities with a diameter of 5 microns or more.

Stable manufacturing of electrospun PVDF/FPU multiscale nanofiber membranes and application of high efficiency protective mask filter elements

Stable manufacturing of electrospun PVDF/FPU multiscale nanofiber membranes and application of high efficiency protective mask filter elements

Conceptual model of electrostatic non-ionizing air filter

Abstract Many infectious diseases such as SARS-CoV-2, rhinovirus, adenovirus, and influenza are transmitted through small respiratory droplets and various filtration systems are used to reduce the risk of airborne infection. Here, we develop a conceptual model of a filter, which is based on the electrostatic deposition of air droplets potentially containing pathogens. Within the model, we explore the effect of polarization of neutral spherical droplets moving in an air flow past cylindrical electrodes. The strength of electric field they produce is low enough to eliminate corona discharge and minimize air ionization, but high enough to capture the droplets. Based on the proposed model, we calculate the filtration efficiency in a quasi-continuous approximation. Also, we conduct numerical simulations of the deposition of respiratory droplets on a compact periodic array of cylindrical electrodes located at the nodes of a square lattice. The droplets with a radius of 10-20 μm pose the greatest threat in spreading the respiratory infections, and as we demonstrate, the proposed system is very effective in capturing droplets of this size, specifically, for a filter element with a width of about 5 mm, the filtration efficiency exceeds 90%.

An enhanced proportional topology optimization method with new density filtering weight function for the minimum compliance problem

This article proposes an enhanced proportional topology optimization (EPTO) method to solve the structural topology optimization problem of minimizing compliance under material volume constraints. In the proposed method, a new filtering weight function based on the improved Heaviside threshold function is adopted to filter element density during the optimization process. The optimization process of the EPTO method consists of an inner loop and an outer loop. In the inner loop, density distribution is modified in combination with a new filtering weight function. By locally averaging the weighted element compliance, an improved density distribution function in the inner loop is put forward to make the topology configuration of the optimized structure more reasonable. In addition, the projection method is used to reduce the number of intermediate density elements, thereby obtaining optimization results with clear boundaries. In the outer loop, a new termination criterion is adopted, which terminates the optimization process by determining that the relative error of the objective function in several consecutive iterations is less than the specified value. The effectiveness and efficiency of the proposed method are demonstrated through several numerical examples involving two-dimensional (2D) and three-dimensional (3D) topology optimization problems. The results of numerical examples show that the proposed method can not only accelerate the convergence of optimization iterations, but also obtain optimized structures with smaller objective function values and better topology configurations. HIGHLIGHTS A new density filtering weight function is proposed based on an improved Heaviside threshold function. An improved inner loop density distribution formula is proposed by combining a new filtering weight function. Using projection based methods to suppress the appearance of intermediate density elements. Verify the effectiveness of the proposed algorithm by comparing the optimization results with existing algorithms such as top88 and PTO.

АНАЛИЗ ПРОБЛЕМ, ВОЗНИКАЮЩИЕ ПРИ ЭКСПЛУАТАЦИИ ПЕСЧАНЫХ СКВАЖИН

The article considers the causes of the formation of mechanical impurities in deep pump wells and the consequences that it entails for the listed reasons. The impact of solid floating particles in the liquid on the well equipment and the importance of improving the filtration technology of sand- containing liquid to prevent it has been noted. As a method used in the fight against mechanical impurities, the advantages and disadvantages of the filter design, which washes the filter element without lifting the pumping equipment, and the V-shaped wire slotted grilles made of durable stainless steel located in the filter compartment are considered. In practical methods of combating mechanical impurities, the main directions of technology for equipping the bottom areas of wells with filters and the main criteria for combating the negative effects of mechanical impurities are indicated. Based on the special importance of the problem of reducing solid floating particles in the production of a gas-liquid mixture, several methods of insulating sand from impurities used in oil production are considered to protect deep pumping equipment. It is established that solving the problem of increasing the reliability of pumping equipment in the presence of solid float particles in the reservoir fluid requires an integrated approach to the selection of technical means. Analysis of the operability of existing filters in the intake of deep pumps showed that they have low efficiency in the fight against solid floating particles, including the need to periodically raise the pumping equipment for cleaning due to the adhesion of solid floating particles to the surface

Evaluation of stresses on the surface of production columns equipped with sand filters when downing into a horizontal well

Relevance. The need to estimate the time of formation sand accumulation near the annulus of a horizontal well and the unit length of filter elements in the bottom of production strings and to determine the stresses on the surface of production strings equipped with sand filters when lowering into the well. Aim. Based on a study of the reasons for the continued flow of sand into wells equipped with anti-sand filters, to develop and propose measures related to the need to choose a reduction in the number of filters that provide the design flow rate of a horizontal well or a significant increase in the length of the filtering surface of the filters in order to reduce erosive wear of the wire winding. Objects. We are considering a well with a horizontal section, equipped with sand filters, the same size as the casing strings. It was assumed that the integrity of the surface of the filter elements would be preserved and the conditions for their destruction would be eliminated when lowering into the horizontal shaft. This presupposes the necessary efficient operation of the well throughout the entire operational period. The section of the first set of curvature and the forces arising during this are considered as wellas stability of a pipe string during possible stops. Centralizers are evenly located along the length of the column, then in some sections we will have a multi-span statically indeterminate beam, in each section of which a radial load acts. Methods. When studying the time of formation sand accumulation in the annular space of a horizontal well and a unit length of filter elements in the bottom of production strings, it is necessary at the first stage to determine the stresses on the surface of production strings equipped with sand filters when lowering into the well. Studying the assessment of the existence time of the transition period is of particular interest. This is, in other words, during what operational period there is a complete accumulation of formation sand in the annular space and the transition of formation drainage along the entire length of the horizontal wellbore to drainage of only zones adjacent to the filters. To calculate the fluid flow rate when the annular space of the horizontal well is completely filled with sand, the design values ​​of the AC4.8 formation parameters were used. The maximum value of depressions used in the calculations is assumed to be 1.5 MPa. Results. Consideration of situations that arise when filters are lowered into horizontal wells indicates that the outer surface of the filter elements is not protected from destruction as a result of contact stresses with the walls of the drilled wellbore. To protect against destruction and rubbing open gaps by clay-containing rocks, rigid centralizers should be installed along the edges of the filter elements, the maximum allowable distances between which should not exceed 4.0–4.5 m.

Cross-domain additive learning of new knowledge rather than replacement.

In medical clinical scenarios for reasons such as patient privacy, information protection and data migration, when domain adaptation is needed for real scenarios, the source-domain data is often inaccessible and only the pre-trained source model on the source-domain is available. Existing solutions for this type of problem tend to forget the rich task experience previously learned on the source domain after adapting, which means that the model simply overfits the target-domain data when adapting and does not learn robust features that facilitate real task decisions. We address this problem by exploring the particular application of source-free domain adaptation in medical image segmentation and propose a two-stage additive source-free adaptation framework. We generalize the domain-invariant features by constraining the core pathological structure and semantic consistency between different perspectives. And we reduce the segmentation generated by locating and filtering elements that may have errors through Monte-Carlo uncertainty estimation. We conduct comparison experiments with some other methods on a cross-device polyp segmentation and a cross-modal brain tumor segmentation dataset, the results in both the target and source domains verify that the proposed method can effectively solve the domain offset problem and the model retains its dominance on the source domain after learning new knowledge of the target domain.This work provides valuable exploration for achieving additive learning on the target and source domains in the absence of source data and offers new ideas and methods for adaptation research in the field of medical image segmentation.

A new hybrid fixed and adaptive gains control algorithm to reduce power losses on LLCL filter-based renewable energy conversion systems with systematic parametrization using Grey Wolf optimizer

Currently, there is a transition in the energy matrix around the world, where traditional sources of energy generation are continually being replaced by energy generation systems based on renewable sources to mitigate the climate crisis. In this bias, this work presents the mathematical modeling of an LLCL filter, used to connect power generation systems based on renewable energy sources to the electrical grid, and presents a novel hybrid fixed-and adaptive gains control strategy for current injection into the grid using this system. The developed hybrid controller is composed of a proportional–integral controller and a direct robust adaptive controller. The first term of the controller guarantees the reference current, while the second term of the controller is used for disturbance rejection. Furthermore, a systematic procedure for the controller’s parametrization based on Grey Wolf Optimizer is also provided. The control of the current injected into the grid is carried out considering the LLCL filter without passive damping resistors in the filter structure to avoid power losses due to the passive filter elements. Additionally, the LLCL filter model considers minimal parasitic resistances to evaluate the controller’s performance and optimize it for the application of interest, aiming to maximize the system performance by ensuring a short transient regime due to the fast closed-loop system response. Simulation results indicate high performance of this optimized control strategy with small tracking error even considering grid impedance variations.

Design and optimization of a novel porous plate oil–gas separator

In the oil-injection compressor system, it is necessary to separate the lubricating oil by sequentially applying the mechanical separator and the separating filter element, however, the oil–gas separation filter has disadvantages such as short service life, high cost, and great environmental pollution. In this paper, a porous plate separator is proposed to achieve the coalescence of small oil droplets, and then the larger droplets can be removed by mechanical collisions driven by turbulence flow in the separator. This device is designed to be used after the primary separator, in the hope of replacing the separation filter element. The structure of the porous plate oil–gas separator is constructed through the staggered arrangement of two porous plates, and the two-phase flow characteristics in the separator are simulated through the Euler-Lagrangian method with the droplet’s behavior of collision and breakup considered. The hole diameter, hole distance, plate distance, and inlet velocity are the key parameters of the separator, and these parameters are combined through the orthogonal design method to form several different structures and working conditions. The results of range analysis and pressure difference distribution under different layers are analyzed comprehensively, so the best combination is determined in terms of particle size growth rate, oil separation efficiency, and pressure loss. The designed structure is machined, and a test bench is set up, so the performance of the porous plate separator is experimentally tested. It is found that the simulation results are in good agreement with the experimental data, and the best simulated conditions are also verified by the experiment. When the inlet velocity is 0.2 m·s−1, the optimal scheme is suggested as follows: Hole diameter = 1.5 mm; Hole distance = 3 mm; Plate distance = 1 mm; plate layers = 40.

Filter Elements Based on Aluminosilicate Fibers for Selective Catalytic Reduction of Nitrogen Oxides — a Review

Filter Elements Based on Aluminosilicate Fibers for Selective Catalytic Reduction of Nitrogen Oxides — a Review

Justification of the Locations of Differential Pressure Sensors for Coarse and Fine Filter Elements Installed one Inside the Other in a Single Gas Filter Housing

Statement of the problem. The relevant task of ensuring the uninterrupted operation of modern gas pressure reduction systems is to develop and comprehensively substantiate the possibility of using two-stage filters for natural gas purification in gas reduction points and theoretically substantiate the method for calculating the pressure drop in cylindrical filter elements (CFE). Results. It is proved that when gas flows in the upper cross section of the filter, the pressure drop will be less than in lower cross sections, including the pressure drop in the lowest cross section. This leads to a larger amount of leaking gas, to a larger mass of impurities settling in the lower part of the filter elements of cylindrical coarse and fine cleaning and to a greater degree of their clogging. Therefore, it is recommended to place gas pressure sensors in the lower part of the internal volume of the coarse and fine-cleaned CFE, so that the flow direction of the coarse and finely purified gas washing the sensors at the location of the hole for measuring statistical pressure is tangential to the side surface of the sensor tube. Then the flow direction of the roughly and finely purified gas entering the holes of the sensors is carried out at an angle of 90° and the pressure gauges measure the static pressure. Conclusions. The locations of pressure drop sensors on coarse and fine filter elements installed one inside the other in a single gas filter housing are substantiated. The proposed arrangement of differential pressure sensors will significantly increase the possibility of receiving an earlier signal about the degree of clogging of the gas filter at the control room, as well as have a significant amount of time for timely removal of blockages formed in the coarse cleaning CFE and replacement of fine cleaning CFE.

Adoption of Bloom Filter and Firebase Framework to Enhance Authentication Time for Healthcare Systems Based on Blockchain Technology

Healthcare offers several advantages for actual-time smart healthcare. security concerns are growing due to its constrained computing power, storage capacity, and self-defense capabilities. The tamper-resistant decentralized architecture of more recent blockchain-based authentication solutions gives them significant security features, but they come with a high resource cost because they need a lot of processing power, additional storage, and lengthy authentication processes. Therefore, these challenges offer impediments to achieving the optimal degrees of temporal efficiency and scalability, which are critical for the effective operation of large-scale, time-sensitive IoHT systems. Our work provides an authentication solution specifically created for healthcare systems to address these issues. We work in three phases: initializing, registering, logging in, and authenticating. The suggested system combines blockchain technology, Firebase Framework, Bloom Filter, Multi-Factor authentication, and other elements to improve security and efficiency at the same time. We use the Python programming language to simulate the work, and our findings indicate that the Bloom filter decreases the amount of time it takes to determine whether a person is in the system compared to the previous way. Moreover, using Firebase may reduce transaction numbers by up to 73%. Using the Scyther tool, a security analysis of the proposed scheme proved that the suggested plan is safe from possible threats and maintains the IoHT system's scalability

Modeling of Filtration Phenomenon in Hydrostatic Drives

Some users consider modern hydrostatic drives and controls to be unreliable and difficult to maintain. This view is often due to operational problems caused by issues with obtaining and then maintaining the appropriate cleanliness class of the working fluid. Recommendations on the selection of appropriate filtration system elements can be found in the literature, but there is no numerical model that could be helpful in a detailed analysis of the phenomenon. In the article, the authors tried to fill the research gap regarding the lack of a filtration model based on the filtration efficiency coefficient of filter elements used in hydraulic drives and controls. The developed model allows users to determine the influence of selected filtration system parameters on the separation of contaminants by filter elements. The model is intended to help designers and users of hydraulic drives and controls in optimizing the filtration system in order to obtain and then maintain the required cleanliness class of the hydraulic fluid. This paper also includes the results of the sensitivity analysis of selected filtration-system operating parameters in terms of the highest efficiency. In order to verify the developed model, experimental tests were also carried out, with the results presented in this paper. Based on the numerical analyses and experimental studies, recommendations that may be helpful in the selection or development of filtration systems used in hydrostatic drives and controls were developed.

Data‐driven predictive control of perturbed buck converters using a modified iterative feedback tuning algorithm

AbstractThe most challenging aspect of utilizing model predictive controllers (MPCs), particularly those involving power electronic applications, is the extraction of a model that accurately represents the behavior of the studied system. Concerning the use of power electronic applications, as long as an MPC is used, adjusting the controller parameters brings difficulties. In addition, as the number of elements increases, it becomes harder to get the best control law out of the model. To do away with the need for model extraction, this study presents an offline data‐driven approach in conjunction with the MPC that can optimally adjust the MPC parameters based on the iterative feedback tuning (IFT) algorithm called the iterative feedback predictive controller (IFPC). The proposed method eliminates concerns regarding selecting an optimal number of algorithm iterations, thereby reducing operating costs, by introducing a modified IFT called feedback‐based IFPC (FIFPC) while simultaneously achieving optimal MPC parameters. The proposed method is applied to a constant voltage load (CVL) connected less‐than‐ideal buck converter, that is, one with perturbed filter elements and variable loads. A robust stability analysis (RSA) is performed under normal operating conditions to investigate the robustness behavior of the proposed controller. Simulation studies are presented to evaluate the proposed controller under different scenarios, such as step and abrupt load changes and measurement noise, compared with the well‐known model‐based and data‐enabled predictive controller (DeePC) approaches in the MATLAB/Simulink environment.

Study on adsorption and purification materials for ethylene in cold storage

In view of the lack of systematic quantitative and comparative studies on the purification effect of ethylene adsorbent in cold storage, starting from the selection of purification materials, this paper analyzed the purification effect of different zeolite materials on ethylene through a small test chamber, and screened out the best zeolite adsorbents used in self-made purification device. Combined with characterization analysis, purification efficiency evaluation and adsorption capacity of zeolite material, the removal performance of ethylene was investigated. The results showed that the zeolite samples with rough and porous surface showed better adsorption performance for ethylene. The larger the specific surface area and total pore volume, the stronger the adsorption capacity to ethylene. In addition, the presence of Na elements and mesoporous increased the exchange capacity and pore volume, which also played a certain role in the ethylene adsorption process. Experimental result demonstrates that clean air volume (CADR) of ethylene is 232 m3/h, the ethylene removal rate at 30 min is 98.19%, and the purification energy efficiency is 1.39. At the same time, the adsorption capacity of the selected zeolite sample is 1380.5 μg/g by dynamic adsorption experiment, and the service life of the filter element of the self-made purification device is estimated to be 166 days. This study can provide a theoretical basis for ethylene purification in cold storage.

Global and local breakthrough curves: A concept for filtration design through analysis of internal concentration distribution using CFD

Evaluating the filtration performance of a filter design traditionally relies on a global breakthrough curve, which represents changes in outlet concentration over time. This curve does not account for adsorption phenomena inside the filter, often necessitating trial-and-error experimentation for optimizing filter shape. To address this issue, we introduce an innovative approach that employs computational fluid dynamics (CFD) to define local breakthrough curves. These curves represent concentration changes over time at specific points within the filter. By comparing these local breakthrough curves with the conventional global breakthrough curve, we aim to enhance the precision of filter designs. This optimization strategy seeks to achieve shapes that meet predetermined performance targets or improve the efficiency of existing filters. Utilizing CFD-generated local breakthrough curves in the optimization process enables the prediction of essential filter elements required to meet specified performance criteria, such as height and thickness. Moreover, this method identifies underperforming areas in existing filters and suggests strategic avenues for improvement. Our results underscore the utility of CFD-informed local breakthrough curves as invaluable tools for streamlining the filter design optimization process.

Definition of the Change Regulations in the Porosity of Semi-permeable Membranes After the Separation of Dairy Raw Materials

Topicality. The article provides a methodology for calculating structural and physical characteristics of semi-permeable membranes after their use in the technological process. During the operation of the membranes, the permeability decreases due to the clogging of their pores with colloidal substances. As a result, it is necessary to obtain data on the distribution of pores on the surface of the investigated ultrafiltration membrane. The aim of the article is to determine the change regularities in the porosity of the semi-permeable membrane, which is used in the technological process of separating dairy raw materials. This will make it possible to predict hydrodynamic properties of the ultrafiltration membrane. Research methods. A strain-measuring (statistical) method is offered, as well as structural and physical characteristics of semi-permeable membranes are determined in the process of membrane filtration of skimmed dairy raw materials. The possibility of constructing mathematical dependencies and methods for determining physical properties and structural analysis of the semi-permeable membrane is highlighted. This technique makes it possible to define not only the surface of the semi-permeable membrane, but also the surface of the polarisation layer of high molecular weight substances. Results. Based on the research results, the dependences of physical properties and structural components of the semi-permeable membrane after the processing of dairy raw materials are constructed. The results of the conducted study show that after ultrafiltration of skimmed dairy raw materials, the pore sizes undergo significant changes. Conclusions and discussion. An increase in the number of pores with a diameter of less than 10 nm is established. The spectrum of the radii of microcapillaries shifts towards decreasing, which occurs as a result of the deposition of particles of the dispersed phase in the microcapillaries. The implementation of research results can take place in industrial conditions, in order to determine the structural and physical characteristics of different types of membranes during the concentration of liquids of different origins for the development of new modifications of filter elements. The conditions for the industrial use of the obtained results are the resolution of issues relating to the laboratory studies of structural and physical characteristics with production results.

Antibacterial and antiviral PA6-AgNPs microfibers for application as a filter element in facial respirators

Polymeric microfibers are very interesting materials that can be associated with other nanomaterials aiming to obtain specific properties and be used in a wide range of applications. In this study, we prepared different formulations of polyamide 6 (PA6) containing silver nanoparticles (AgNPs) and produced microfibers by solution blow spinning technique for its use as a filter element in a face respirator. The obtained samples were then characterized by field emission gun-scanning electron microscopy (FEG-SEM), energy dispersion spectroscopy (EDS), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), water contact angle (WCA), thermogravimetric analysis (TGA), and respirability and antibacterial, antiviral and cytotoxicity assays. In general, the microfibers were well dispersed and the AgNPs were evenly distributed throughout the samples, reflecting a hydrophilic character and good thermal stability, with a maximum weight loss of 2.9 % attributed to the evaporation of water molecules. The sample produced with a concentration of 10 mmol/L of silver nitrate presented acceptable levels of resistance to respiration. Concerning the microbiological analyses, the results showed that samples evidenced antibacterial effect against Escherichia coli and Staphylococcus aureus, forming inhibition halos of up to 4 mm in disk diffusion assays and inhibiting bacterial growth in liquid medium assays, as well as antiviral effect against betacoronavirus MHV-3, promoting a reduction of up to 99.9 % of viral particles. Moreover, the samples presented cytotoxicity on the first and second days, whereas on the seventh day some of the extracts did not show cytotoxic activity, indicating that the cells adapted to the culture medium. Considering the data set and the simple process of obtaining the microfibers, it was possible to conclude that this material can be applied as a filter element in a face respirator as well as in a variety of products with antibacterial and antiviral purposes.

Bench studies of the process of transporting an inverse gravel filter of block type along the well

The purpose of the study is to develop a technology for fresh water treatment in deep hydrogeological wells with productive horizons represented by medium-grained, fine-grained, and silty sands by equipping their intake part with block-type inverse gravel filters. Experimental studies were carried out using provisions of the general theory of scientific experiment and the theory of random processes. A theory concerning the possibility of equipping the water intake part of hydrogeological wells, being more than 200 m deep, with block-type inverse gravel filters using the proposed technology was further developed. For the first time, the dependence of the maximum depth of transporting block-type inverse gravel filters on the length of their section, the mass concentration of a binding agent, and the ambient temperature was established. A scope of the proposed technology was substantiated. A range of depths for equipping with block-type inverse gravel filters depending on the mass concentration of a binding agent in the polymer-gravel filter element and the length of its section was substantiated.

Crystals of Salts of Nickel and Cobalt Transition Elements for Optical Filters

Crystals of Salts of Nickel and Cobalt Transition Elements for Optical Filters