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As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size. [ABSTRACT FROM AUTHOR]

To reduce the fire risk of air filter paper, a reactive ammonium phosphite flame retardant was synthesized and applied to the flame-retarding treatment of air filter paper. It was found that ammonium phosphite reacted with cellulose existing in filter paper fibers to form P–O–C bonds and remarkably improved the flame-retarding properties and thermal stability of the air filter paper. After modification of the air filter paper with 30 wt% of ammonium phosphite, its limiting oxygen index value reached 39.5%, which remained at 29.6% after 4 h of the dipping test. The heat release rate and total heat release rate of the treated air filter paper decreased significantly, and the carbon residual amounts at 700 °C in the nitrogen atmosphere and in air reached 43.96% and 16.35%, respectively. During thermal decomposition, ammonium phosphite played a flame-retarding role in both condensed and gas phases. Moreover, ammonium phosphite, as a flame retardant, had no obvious influence on the physical properties and filtration performance of the air filter paper. [ABSTRACT FROM AUTHOR]

In this paper, a simple method for hydrophobic modification of polyvinyl alcohol (PVA) was found. Using N-methylpyrrolidone as solvent, PVA was esterified with stearyl chloride without catalyst. The modified hydrophobic polyvinyl alcohol (MPVA) was well verified by FT-IR and XRD. Using air filter paper as receiving substrate and MPVA as spinning solution, MPVA air filter paper with water resistance and high filtration performance was prepared, and hydrophilic PVA air filter paper was prepared as controlled sample. SEM was used to observe the fiber morphology on the surface of the two composite filter papers. The contact angle of hydrophobic MPVA air filter paper (25:3) was 121.9°, and the filtration efficiency was increased to 99.9955 % and the filter initial resistance increased to 90 Pa. [ABSTRACT FROM AUTHOR]

In order to solve the hygroscopicity of ammonium polyphosphate (APP) and improve its flame retardancy, hydrophobic and flame retardant groups were introduced on the surface of APP by means of surface coating. It was blended with styrene acrylic emulsion (AAS) as the reinforcing resin and applied to the automobile engine air filter paper. The structure of the modified particles was confirmed by FT-IR TGA showed that the initial decomposition temperature of the modified particles decreased by 15 ℃, the decomposition rate decreased by about 5%, and the carbon residue rate at 800 ℃ increased from 21.73 to 44.92%; The DSC displayed that the blend resin had fine compatibility. Particle size analysis, scanning electron microscopy and transmission electron microscopy demonstrated that the large size modified APP particles were diffused into styrene acrylate emulsion particles and reconstituted to form a more compact and smaller particle size. The particles had a core shell structure with a shell thickness of 17 nm. These phenomena revealed the evolution of latex particles after blending. The air filter paper reinforced by blend resin has better mechanical properties and good water resistance. After absorbing water, the burst retention rate of air filter paper is more than 50%, and the stiffness retention rate is more than 20%. The combustion test and analysis by cone calorimeter analysis that the blend resin give the air filter paper excellent flame retardant performance. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the rapid development of the automotive industry, people have put forward higher requirements for automotive air filter paper, hoping that it can meet the more complex air environment. Therefore, there is an urgent need to develop "green" multifunctional air filters with excellent filtration efficiency, flame retardancy, hydrophobicity, antibacterial properties and low cost. In this work, a multifunctional cellulose-based air filter paper with flame retardant, antibacterial and hydrophobic properties was prepared from mercerized pulp and softwood pulp via chemical treatment with pre-synthesized N, N -biguanide-diethyl phosphonic acid (AGDEPA) and octadecyl trichlorosilane (OTS). Due to the high nitrogen and phosphorus content of AGDEPA, the air filter paper shows remarkable self-extinguishing behavior and have no afterglow with an intact textile structure. The limiting oxygen index (LOI) value of air filter paper reached 38.8%, meeting the industry standard for flame retardant materials. Antimicrobial tests confirm that the killing efficiency against E. coli and S. aureus reached 93.9% and 99.99%. Furthermore, OTS containing hydrophobic long chains successfully constructed a multi-layer micro/nanostructure on the paper surface, and its contact angle to water was up to 153.6°. The addition of mercerized fibers also effectively improves the air permeability of the filter paper, which can reach 619 L/m2·s, and subsequent impregnation avoided the impact on the pore size of the material. • A new N-P flame retardant and antimicrobial agent was synthesized and fixed to the paper fibers by chemical grafting. • Excellent flame retardant, antibacterial and hydrophobic properties were achieved. • The high permeability and mechanical properties of filter paper meet the needs of practical use. • The green, low-cost, multi-functional all-fiber air filter material was realized. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Air filters are placed upstream of internal combustion engines to remove dust particles in the suction air. In this article, we examine the acoustic characterization of an air-filtering unit in the absence of mean flow. For this purpose, a circular air-filtering unit with an axial inlet and side outlet widely used in the automobile industry is considered. The air-filter element is modeled as an equivalent acoustic fluid with finite flow resistivity. The flow resistivity of the region is estimated from the permeability of the filter paper and the geometrical arrangement of the paper folds (pleats) inside the air-filter element using an electrical analogy. A numerical model based on the finite element method (FEM) and an analytical model using classical one-dimensional plane wave analysis (1-D PWA) was developed. Experiments were carried out using an impedance tube to estimate transmission loss. A good correlation is observed between the FEM model and the experiments. The results obtained from the 1-D PWA are in reasonable agreement with those obtained from the other two methods. [ABSTRACT FROM AUTHOR]

• ZIF-67 particles can be evenly distributed and tightly attached to the cellulose paper substrate. • Mild synthesis conditions combined with papermaking processes are suitable for mass production. • The composite filter has a hierarchical porous structure with a large specific surface area. • The optimum sample exhibited removal efficiencies of 98.52% for PM 2.5 and 99.00% for PM 10. • Composite papers possessed excellent mechanical properties and reusability. The combination of functional zeolitic imidazolate frameworks (ZIFs) with suitable substrates is promising for the preparation of advanced filtering materials. In this study, the bleached kraft softwood pulp (NBKP) was composited with ZIF-67 particles via an in situ growth method to fabricate functional paper. Enabled by the traditional papermaking process, ZIF-67 crystals were uniformly and tightly anchored on cellulosic fibers in a facile and economic way. The introduction of ZIF-67 boosted the mechanical performances of the composite paper owing to the presence of electrostatic interactions and hydrogen bonds. Meanwhile, the resultant paper presents hierarchical porous structure with a large specific surface area of 327.07 m2·g−1. The filters with hierarchical pore structure will provide a complex tortuous channel for passing particulates, which can increase the frequency of effective collision between filters and particulates. Air filtering tests demonstrated that the ZIF-67 entrapped paper has superior particle removal efficiency with a low pressure drop and a large dust holding capacity. The optimal ZP-3 sample displayed removal efficiencies of 98.52 % for PM 2.5 and 99.00 % for PM 10. Meanwhile, filtration quality factors were calculated to be 0.15 (PM 2.5) and 0.17 (PM 10), respectively. The filter also has good antibacterial activity. In addition, ZP-x composite paper is easy to regenerate and possesses good reusability. The high-efficient ZP-x filter will have potential applications in fields of air purification. [ABSTRACT FROM AUTHOR]

The filter paper of automobile engine air filter is easy to temper and causes combustion. Flame retardant is usually added to the reinforced resin styrene-acrylic emulsion (SAE) to improve the flame-retardant performance of the air filter paper. Ammonium polyphosphate (APP) was used as material in this research, and multi-layer coated APP was prepared by microcapsule coating. A layer of nano-scale SiO2 was coated and then introduced organosiloxane structure of the allyl polyoxypropylene ether side chain and boron. The chemical groups and structural composition were determined by Fourier transform infrared spectroscopy. TGA characterized the modified particles' high-temperature stability. By scanning electron microscopy and TEM, the morphologies of modified particles were analyzed to reveal the evolution of modified APP in SAE. Finally, nanoparticles with core-shell structures were formed. Applying the blended resin to the air filter paper, the flame-retardant performance was greatly improved. Total heat release (THR), heat release rate (HRR), peak heat release rate (pkHRR), mass loss rate (MLR), and effective heat of combustion (EHC) were reduced, respectively, by 30.8%, 30.7%, 42.0%, 16.7%, and 14.4%. The time to ignition (TTI) was doubled, so the fire spread could be effectively suppressed. Meanwhile, nano latex particles were attached to the interwoven fibers points and formed a "sea-island structure," which significantly improved the paper's mechanical properties, with bursting strength, tensile strength, stiffness, fracture work, and elongation increased by 18.60%, 5.72%, 10.64%, 17.00%, and 81.80%, respectively. It solved the problem that the inorganic flame-retardant particles often lead to the deterioration of the mechanical properties of paper. [ABSTRACT FROM AUTHOR]

With the wide application of lithium‐ion battery in various fields, the security and reliability of lithium‐ion battery have attracted great attention. Under the mode of continuous development of Internet of vehicles technology, vehicles will be connected with each other in the future, and the hackers will attack the energy system of the vehicle. However, health assessment of lithium‐ion battery can timely grasp the running state and health of the power battery system, so as to realize active defense against hacker security attacks. This paper proposes a health assessment method for lithium‐ion batteries using incremental capacity analysis and weighted Kalman filter algorithm. In view of the problem that ordinary Kalman filtering algorithm produces poor filtering results when the actual measurement noise error is large, this paper proposes a weighted Kalman filtering algorithm based on ordinary Kalman filtering. Incremental capacity analysis was performed on the charge and discharge data of lithium‐ion batteries, and health characteristics were extracted to construct a Gaussian nonlinear feature association mapping model for the health characteristics of lithium‐ion batteries. Combined with the battery SOH double‐exponential decay model, the weighted Kalman filter algorithm was used to evaluate the health of lithium‐ion batteries. Four lithium‐ion battery data sets provided by NASA were used to simulate and verify the health assessment method proposed in this paper. The verification results show that the health assessment method based on weighted Kalman filter proposed in this paper has better assessment accuracy than the common Kalman filter method with an average percentage error of 0.61%. The average percentage error of the assessment results for different types of batteries was less than 0.9%. The health assessment method has high accuracy and is suitable for different types of batteries. [ABSTRACT FROM AUTHOR]

This paper considers the problem of target tracking in complex manoeuvering scenarios with a lack of relevant prior knowledge. This is a challenge for classical model‐based manoeuvering target tracking algorithms because they rely heavily on accurate domain and prior knowledge of target motion. To address this problem, we propose a hybrid‐driven continuous‐time filter algorithm in this paper, which combines the advantages of the model‐driven and data‐driven. We use the stochastic differential equation (SDE) with the acceleration model as the basic framework of the proposed algorithm. In order to deal with unpredictable manoeuvres and unknown perturbations, we adopt neural networks as data‐driven to estimate target accelerations and compensations of composite perturbations in real time using historical and current measurements. And the direction of gradient descent of the neural network is constrained by the motion model, thus the learning efficiency of the network and the interpretability of the proposed algorithm is improved. The proposed algorithm can simultaneously utilise historical trajectory information and domain knowledge as hybrid‐driven to achieve complex manoeuvering target tracking with little prior information. Experimental results demonstrate the superiority of our algorithm in tracking accuracy, robustness and environmental adaptability. [ABSTRACT FROM AUTHOR]

Zein as a natural protein had been widely used in various fields due to its biodegradability and biocompatibility. However, its sensitivity to humidity and poor mechanical performance limited its application in practice. In this study, zein-based composite nanofibers loaded with curcumin were prepared by electrospinning assisted with polyvinyl alcohol (PVA). The filtration efficiency of the modified nanofibers to the particles with diameters larger than 0.5 μm was all above 98%. The loaded curcumin interacted with protein molecular chains to form a network structure within tightly connected nanofibers, which exhibited excellent moisture resistance and good adhesion to cellulose paper towels used as air filter substrates. Meanwhile, its tensile strength had also been enhanced vastly to 0.72 MPa compared with the initial tensile strength of 0.21 MPa. This study provides a new electrospinning strategy for the preparation of zein-based composite nanofibers that can be widely utilized in air filtration with high moisture resistance. [ABSTRACT FROM AUTHOR]

Copyright of Nigde Omer Halisdemir University Journal of Engineering Sciences / Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi is the property of Nigde Omer Halisdemir Universitesi (NOHU), Muhendislik Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Science & Technology of Cereals, Oils & Foods is the property of Science & Technology of Cereals, Oils & Foods Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fuel cell air filter can absorb harmful impurities and gases to fuel cell and is an important component to ensure the service life of fuel cell. The previous researches mainly focus on the activated carbon and filter paper materials in the laboratory. The object of this paper is the fuel cell air filter product assembly being used by the main engine plant. According to the tests of air filters with different carbon contents, it was found that the adsorption efficiency of current products for NO2 was better than that of C7H8, SO2 and C4H10. Based on the adsorption mechanism of activated carbon for different gases, the adsorption difference was explained. The testes also found that there was no direct relationship between the change of carbon content of products containing activated carbon and the fractional filtration efficiency. The main reason is that the gap between the activated carbon particles is large, which cannot effectively intercept dust particles. The filtering of small size particles still depends on the melt-blown layer material in the air filter element and its electrostatic electret process. It was also found that there was a positive correlation between inlet air resistance and carbon content, and a negative correlation between dust holding capacity and carbon content. This test results can help the main engine factory understand the performance and improvement direction of products. [ABSTRACT FROM AUTHOR]

The performance of an air purifier is determined by its clean air delivery rate (CADR), expressed as the product of the air flowrate and filter collection efficiency. A high CADR in a commercial air purifier is achieved using a pleated air filter with high filtration performance at a given air flowrate. However, obtaining this high filtration performance depends on the knowledge of the manufacturer, including the optimal pleating design, which remains uncertain to date. In this study, test pleated filters were prepared by folding a flat electrostatically-charged E12 filter medium to obtain different pleating geometries. The proper pleat geometry of the pleated filter, which has a minimum pressure drop at a fixed air flowrate, was dependent on the pleat length (P L ) and pleating ratio (α = pleat height/pleat width), wherein as the P L increases, the α range required to achieve a minimum pressure drop similarly increases. Based on the filter quality factor (q F ), the optimal pleat geometry of a pleated filter was between α values of 6-8, irrespective of the P L . Although both P L and α have certain influences on the q F , α has a greater influence on the pleated filter with no dead zone., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

This paper presents an experimental study of the effect of the mass of dust retained on a fibrous filter bed operating singly and in a "cyclone-filter-bed" system on changes in filtration efficiency and accuracy, as well as the increase in flow resistance. The research was carried out using a novel and unprecedented method, determining the dust absorption coefficient km of the filter baffle under laboratory conditions. A filtration system built of a single cyclone and a cylindrical filter cartridge with an appropriately sized surface set behind it was studied. Conditions corresponding to the actual operating conditions of the air filter were maintained: dust concentration, filtration speed and dust extraction from the cyclone settling tank. The purpose of the research was to evaluate filter materials with different structures in terms of filtration efficiency and accuracy, as well as flow resistance. The study showed that the parameters of the structure of filter materials—permeability, grammage and thickness—affect the process of retaining dust particles. It was shown that the increase in the flow resistance of the filter bed has a higher intensity when dust grains of small sizes are directed at it, which is the case when the bed is operated behind a cyclone, which separates larger dust grains from the air. There is a reduction in the operating time of the filtration system due to the limitation of the permissible resistance ∆pfdop, and the corresponding dust absorption km has a lower value. For a fixed value of the flow resistance, the dust absorption coefficient km2 of three different filtration baffles AC, B2, and B, working with a cyclone, take values 50–100% smaller than when working in a single-stage system. It has been shown that the "cyclone-filter baffle" unit, due to its greater dust separation capability, allows the filter cartridge to operate for a longer time until a certain flow resistance is reached. This allows the unit to operate longer at lower flow resistance without changing the filter cartridge, thus saving energy. The km values obtained during the tests, using the proposed original method, allow the selection of the filter bed for specific vehicle operating conditions by modelling its course. [ABSTRACT FROM AUTHOR]

We report the use of a laser-based fabrication process in the creation of paper-based flow-through filters that when combined with a traditional lateral flow immunoassay provide an alternative pathway for the detection of a pre-determined analyte over a wide concentration range. The laser-patterned approach was used to create polymeric structures that alter the porosity of the paper to produce porous flow-through filters, with controllable levels of porosity. When located on the top of the front end of a lateral flow immunoassay the flow-through filters were shown to block particles (of known sizes of 200 nm, 500 nm, 1000 nm and 3000 nm) that exceed the effective pore size of the filter while allowing smaller particles to flow through onto a lateral flow immunoassay. The analyte detection is based on the use of a size-exclusive filter that retains a complex (∼3 μm in size) formed by the binding of the target analyte with two antibodies each of which is tagged with different-sized labels (40 nm Au-nanoparticles and 3 μm latex beads), and which is larger than the effective pore size of the filter. This method was tested for the detection of C-reactive protein in a broad concentration range from 10 ng/ml to 100,000 ng/ml with a limit-of-detection found at 13 ng/ml and unlike other reported methods used for analyte detection, with this technique we are able to counter the Hook effect which is a limiting factor in many lateral flow immunoassays. [Display omitted] [ABSTRACT FROM AUTHOR]

Multifunctional air filters with efficient particulate matters (PMs) removal, low respiratory resistance and prevention harmful substances are highly demanded. Bacterial cellulose (BC) air filter can capture PMs and separate them from the airflow; however, the dense network structure sacrifices the air permeability. Herein, we incorporated silver nanowires (AgNW) to BC filter through in‐situ cultivation method to prepare a new air filter. The addition of AgNW endows BC filter with antibacterial activity and increases the porosity and air permeability. Surprisingly, AgNW incorporation achieves high‐efficiency filtration through electrostatic adsorption. The filtration efficiency of the BC/AgNW composite filter paper for PM2.5 and PM10 is as high as 99.7% and 99.8%, respectively, that are on par with commonly used 3 M masks on the market. The pressure drop is 123 Pa, which can meet market demand with satisfaction. In addition, the tailor‐made BC/AgNW owns efficient antibacterial potency to keep the human body from infecting germs and other interferences. Overall, this work indicated that the versatile composite air filter paper is promising for various applications in the environmental field and the critical need for human health. [ABSTRACT FROM AUTHOR]

Under the goal of "achieving carbon peak by 2030 and carbon neutrality by 2060", how to select the type of fresh air system has become a key area of energy conservation. The method of outdoor design PM2.5 concentration is one of the important factors affecting the selection of fresh air filtration system. This paper first analyzed the PM2.5 concentration values of 31 cities in China from 2017 to 2020 based on mathematical induction, and next gave the recommended coefficient K under six urban economic regions methods in combination with the actual situation. Finally, the selection of air filters in five typical cities was taken as an example, the differences in recommended coefficient K and selection of outdoor design PM2.5 concentration under different recommended methods were compared and analyzed. The results showed that the recommended coefficient K under the six economic regions could meet the required K value needs of the region. The recommended coefficient K by the six economic regions methods based on per capita GDP is the best. Under that conditions, the recommended coefficient K of the five typical cities under strict and normal conditions differs from the average K values of the six methods by 0.06 and 0.04. This paper will provide a new method for the correct selection of outdoor design PM2.5 concentration in fresh air systems to achieve the dual carbon energy-saving goal. [ABSTRACT FROM AUTHOR]

The application of cellulose nanocrystals (CNCs) as a PM2.5 capture agent is demonstrated. CNCs are prepared using sulfuric acid hydrolysis of laboratory filter paper. The obtained CNCs are characterized to obtain their molecular information, morphology, and crystallinity using ATR FT-IR spectroscopy, transmission electron microscopy, and X-ray diffraction, respectively. The negatively charged surfaces of the CNCs with an average zeta potential of −51 mV could strongly interact with PM2.5 particles, and are principally utilized for PM2.5 capture. In order to evaluate the PM2.5 removal efficiency of the CNCs, they are fabricated into an air filter by dip-coating onto a cotton mesh fabric employed as the substrate. The CNCs could be homogeneously coated onto the cotton fibers, as observed via scanning electron microscopy. The air filter fabricated using the optimized conditions possesses a PM2.5 removal efficiency of 94%. The CNC-coated air filter has good air penetrability, with a low pressure drop of 20.7 Pa. The surfaces of the air filters before and after PM2.5 capture are characterized using optical microscopy and scanning electron microscopy. The PM2.5 capture mechanism of the CNC-based air filter is also proposed. Our findings reveal the important discovery that negatively charged CNCs can be directly employed as a renewable PM2.5 capture agent. [ABSTRACT FROM AUTHOR]

In recent years, the Mineral Liberation Analyser (MLA) has played a pivotal role in analysing respirable and inhalable ambient air samples collected on filters from both underground coal and metalliferous mines. Leveraging backscattered electron (BSE) image analysis and X-ray mineral identification, the MLA offers automated quantitative mineral characterization. The escalating prevalence and severity of mine dust lung diseases, particularly among young miners, have reignited interest in comprehensively understanding the dust's characterization, encompassing mineralogy, particle size, and shape. Merely measuring total respirable dust exposure and its duration based on gravimetrically determined weight is no longer deemed sufficient in addressing the evolving landscape of occupational health challenges in mining environments. Since the publication of previous studies, efforts have been dedicated to refining the Mineral Liberation Analyser (MLA) methodology for respirable dust sampling. This refinement, discussed in detail in this paper, encompasses various enhancements, such as the implementation of data checks to identify carbon contamination, backscattered electron (BSE) drift, and the misclassification of X-ray spectra. Additionally, an examination of sampling efficiency led to the exploration of using smaller samples as an alternative to the time-intensive analysis of entire filters. Furthermore, this paper presents a reanalysis of paired filter sample sets previously reported using the Sarver Group Methodology. These samples are subjected to analysis using the Mineral Liberation Analyser, providing a more detailed illustration of the outputs derived from the updated methodology and compared to previously published MLA data. [ABSTRACT FROM AUTHOR]

The purpose of this study was to empirically evaluate the performance of fibrous materials that meet the criteria for inlet air filtration in internal combustion engines. The characteristics of filtration efficiency and accuracy, as well as the characteristics of flow resistance, were determined based on the mass of dust accumulated in the filter bed during the filtration process. Single-layer filter materials tested included cellulose, polyester, and glass microfiber. Multilayer filter media such as cellulose–polyester–nanofibers and cellulose–polyester were also examined. A new composite filter bed—consisting of polyester, glass microfiber, and cellulose—and its filtration characteristics were evaluated. Utilizing specific air filtration quality factors, it was demonstrated that the composite is characterized by high pre-filtration efficiency (99.98%), a short pre-filtration period (qs = 4.21%), high accuracy (dpmax = 1.5–3 µm) for the entire lifespan of the filter, and a 60–250% higher dust absorption coefficient compared to the other tested materials. A filtration composite bed constructed from a group of materials with different filtration parameters can be, due to its high filtration efficiency, accuracy, and dust absorption, an excellent filter material for engine intake air. The composite's filtration parameters will depend on the type of filter layers and their order relative to the aerosol flow. This paper presents a methodology for the selection and testing of various filter materials. [ABSTRACT FROM AUTHOR]

In this study, paper based pristine air filter media composed of cellulose fiber and melamine-formaldehyde (MF) fiber was prepared by wet forming method, then phosphorous-containing poly-acrylate (P-PA) emulsion was used as a strengthen binder to prepared flame retardant air filter media. Effects of MF fiber and P-PA binder content on the basic properties, mechanical properties, air permeability and char yield of the prepared air filter media were studied. The micro-structure of prepared flame retardant air filter media was observed by Scanning Electronic Microscopy. The flame retardancy mechanism of the prepared air filter media was discussed. The result shows that by incorporation of MF fiber and using P-PA binder as a strengthen binder, air filter media with excellent flame-retardancy can be prepared, which was due to a synergistic effect of gas and condensed mechanism. [ABSTRACT FROM AUTHOR]

Marine gas-water separator is mainly used to filter impurities in the air for gas turbine, and it also needs to have certain anti-impact ability in engineering application. In order to study its impact resistance, this paper used the method of combination of simulation and experiment. Firstly, the material properties of 5083 aluminium alloy were determined. On the basis of this, the drop test under different acceleration was carried out. Then ABAQUS software was used to carry on the drop simulation analysis and antiknock simulation analysis. The feasibility of the simulation method was verified by comparison of simulation results and experimental results. The following conclusions are obtained: the impact of 5 g-33 g drop will not affect the operation of the gas-water separator; the impact of guide vane's transverse fall on the gas-water separator is less than that of guide vane's longitudinal fall; the direction with guide vane's support has stronger anti-detonating performance than that without guide vane's support. The conclusions drawn in this paper can be used for specific optimization and protection in practical use, and provide a certain reference for the impact performance field of Marine gas-water separator. [ABSTRACT FROM AUTHOR]

Construction of air filter membranes bearing prominent collecting and transferring capability is highly desirable for detecting airborne pathogens but remains challenging. Here, a hyaluronic acid air filter membrane (HAFM) with tunable heterogeneous micro-nano porous structures is straightforwardly constructed through the ethanol-induced phase separation strategy. Airborne pathogens can be trapped and collected by HAFM with high performance due to the ideal trade-off between removal efficiency and pressure drop. By exempting the sample elution and extraction processes, the HAFM after filtration sampling can not only directly disperse on the agar plate for colony culture but also turn to an aqueous solution for centrifugal enrichment, which significantly reduces the damage and losses of the captured microorganisms. The following combination with ATP bioluminescence endows the HAFM with a real-time quantitative detection function for the captured airborne pathogens. Benefiting from high-efficiency sampling and non-traumatic transfer of airborne pathogens, the real-world bioaerosol concentration can be facilely evaluated by the HAFM-based ATP assay. This work thus not only provides a feasible strategy to fabricate air filter membranes for efficient microbial collection and enrichment but also sheds light on designing advanced protocols for real-time detection of bioaerosols in the field., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

To protect occupants in vehicle cabin environments from the health risks of high concentrations of particulate matter (PM), it is important to install vehicle cabin air filter (VCAF) to eliminate PM. In this study, we investigated the filtration performance of 22 VCAFs. Results showed that the minimum average filtration efficiency was 56.1 % for particles with a diameter of 0.1-0.3 μm, a pressure drop of 33.2-250 Pa at air velocity of 2.5 m/s, and the dust-holding capacity ranged from 5.8 to 19.4 g. In addition, as the filter area increased from 0.23 m 2 to 0.50 m 2 , the filtration efficiency for particles with a diameter of 0.1-0.3 μm increased from 56.7 % to 77.5 %, the pressure drop decreased from 96.1 to 62.5 Pa, and the dust holding capacity increased 2.7 times. Furthermore, we compared the service life of VCAF from 31 major Chinese cities and found that the service life varied greatly from maximum of 1730 h for Haikou to minimum of 352 h for Shijiazhuang. Considering occupant health risks, Beijing requires that VCAFs have PM 2.5 filtration efficiency at least 88.1 %, and Liaoning requires minimum of 97.5 %. Hence, choosing the appropriate VCAF based on the atmospheric environment of different cities deserves our attention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In this study, paper based pristine air filter media composed of cellulose fiber and melamine-formaldehyde (MF) fiber was prepared by wet forming method, then phosphorous-containing poly-acrylate (P-PA) emulsion was used as a strengthen binder to prepared flame retardant air filter media. Effects of MF fiber and P-PA binder content on the basic properties, mechanical properties, air permeability and char yield of the prepared air filter media were studied. The micro-structure of prepared flame retardant air filter media was observed by Scanning Electronic Microscopy. The flame retardancy mechanism of the prepared air filter media was discussed. The result shows that by incorporation of MF fiber and using P-PA binder as a strengthen binder, air filter media with excellent flame-retardancy can be prepared, which was due to a synergistic effect of gas and condensed mechanism. [ABSTRACT FROM AUTHOR]

A lot of manual work goes into identifying a topic for an article. With a large volume of articles, the manual process can be exhausting. Our approach aims to address this issue by automatically extracting topics from the text of large numbers of articles. This approach takes into account the efficiency of the process. Based on existing N-gram analysis, our research examines how often certain words appear in documents in order to support automatic topic extraction. In order to improve efficiency, we apply custom filtering standards to our research. Additionally, delete as many noncritical or irrelevant phrases as possible. In this way, we can ensure we are selecting unique keyphrases for each article, which capture its core idea1. For our research, we chose to center on the autonomous vehicle domain, since the research is relevant to our daily lives. We have to convert the PDF versions of most of the research papers into editable types of files such as TXT. This is because most of the research papers are only in PDF format. To test our proposed idea of automating, numerous articles on robotics have been selected. Next, we evaluate our approach by comparing the result with other models. [ABSTRACT FROM AUTHOR]

Ambient fine particulate matter (PM 2.5 ) is a leading environmental risk factor globally, and over half of the associated disease burden are caused by cardiovascular disease. Numerous randomized controlled trials (RCT) have investigated the short-term cardiovascular benefits of indoor air purifiers (IAPs), but major knowledge gaps remain on their longer-term benefits. In this 1-year, randomized, double-blinded, parallel controlled trial of 47 elderly (n true-purification  = 24; n sham-purification  = 23) aged ≥70 years, true-purification reduced household PM 2.5 levels by 28% and maintained lower exposure throughout the year compared to the sham-purification group. After 12 months of intervention, a significant reduction of diastolic blood pressure was found in the true-purification versus sham-purification group (-4.62 [95% CI: -7.28, -1.96] mmHg) compared to baseline measurement prior to the intervention, whereas systolic blood pressure showed directionally consistent but statistically non-significant effect (-2.49 [95% CI: -9.25, 4.28] mmHg). Qualitatively similar patterns of associations were observed for pulse pressure (-2.30 [95% CI: -6.57, 1.96] mmHg) and carotid intima-media thickness (-10.0% [95% CI: -24.8%, 4.7%]), but these were not statistically significant. Overall, we found suggestive evidence of cardiovascular benefits of long-term IAPs use, particularly on diastolic blood pressure. Evidence on other longer-term cardiovascular traits is less clear. Further trials with larger sample sizes and long-term follow-up are needed across diverse populations to evaluate the cardiovascular benefits of IAPs., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Ka Hung Chan reports financial support was provided by BHF Centre of Research Excellence. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

This paper proposes an accurate lidar-based outdoor localization method that requires few computational resources, is robust in challenging environments (urban, off-road, seasonal variations) and whose performances are equivalent for two different sensor technologies: scanning LiDAR and flash LiDAR. The method is based on the matching between a pre-built 3D map and the LiDAR measurements. Our contribution lies in the combined use of a particle filter with a hybrid octree to reduce the memory footprint of the map and significantly decrease the computational load for online localization. The design of the algorithm allows it to run on both CPU and GPU with equivalent performance. We have evaluated our approach on the KITTI dataset and obtained good results compared to the state of the art. This paper introduces the baseline performance on a multi-seasonal dataset we are publicly releasing to the community. We have shown that the same localization algorithms and parameters can perform well in urban environments and can be extended to off-road environments. We have also evaluated the robustness of our method when masking angular sectors of the LiDAR field of view to reproduce edge-cases scenarios in urban environments where the LiDAR field is partially occulted by another vehicle (bus, truck). Finally, experiments have been carried out with two distinctive scanning and flash LiDAR technologies. The performance achieved with the flash LiDAR is close to the scanning LiDAR despite different resolutions and sensing modalities. The positioning performance is significant with 10cm and 0.12° angular RMSE for both technologies. We validated our approach in an off-road environment from a front view field of view with only 768 LiDAR points. [ABSTRACT FROM AUTHOR]

One of the core issues of mobile measurement is the pose estimation of the carrier. The classic Global Navigation Satellite System/Inertial Measurement Unit (GNSS/IMU) integrated navigation scheme has high positioning accuracy but is vulnerable to Global Navigation Satellite System (GNSS) signal occlusion and multipath effect. Simultaneous Localization and Mapping (SLAM) is not affected by signal occlusion, but there are problems such as error accumulation and scene degradation. The multi-sensor fusion scheme combining the two technologies can effectively expand the scene coverage and improve the positioning accuracy and system robustness. However, the current scheme has some limitations. On the one hand, GNSS plays a less important role in most SLAM systems, only for initialization or as a closed-loop factor and other auxiliary work. On the other hand, in the fusion method, most of the current systems only use filtering or graph optimization, without taking into account the advantages of both. Aiming at pose estimation for mobile carriers, this paper combines the advantages of the global optimization of the factor graph and the local optimization of filtering and proposes a GNSS-IMU-LiDAR Constraint Kalman Filter (abbreviated as GIL-CKF), which has the characteristics of full coverage and effectively improving absolute accuracy and high output frequency. The scheme proposed in this paper consists of three parts. Firstly, an extensible factor map is used to fuse the positioning information from different sources, including GNSS, IMU, LiDAR, and a closed-loop map, to maintain a high-precision SLAM system, and the output is used as Multi-Sensor-Fusion-Odometry (MSFO). Then, the scene is divided according to the GNSS quality factor, and a Scene Optimizer (SO) is designed to filter GNSS pose and MSFO. Finally, the results are input into the Extended Kalman Filter (EKF) together with the original IMU data for further optimization and smoothing. The experimental results show that the integration of high-precision GNSS positioning information with IMU, LiDAR, a closed-loop map, and other information through the factor map can effectively suppress error accumulation and improve the overall accuracy of the SLAM system. The SO based on GNSS indicators can fully retain high-precision GNSS positioning information, effectively play their respective advantages of filtering and graph optimization, and alleviate the conflict between global and local optimization. SO with EKF filtering furthers optimization, can improve the output frequency, and smooth the trajectory. GIL-CKF can effectively improve the accuracy and robustness of pose estimation and has obvious advantages in multi-sensor scene complementarity, partial road section accuracy improvement, and high input frequency. [ABSTRACT FROM AUTHOR]

Indoor air quality is important for the health of building occupants, and public interest in controlling indoor airborne pathogens increased dramatically with the COVID-19 pandemic. Pollutant concentrations can be controlled locally using portable air cleaners (sometimes called air purifiers), which allow occupants to apply air cleaning technology to meet their needs in the location and times that they find appropriate. This paper provides a systematic review of scientific literature that describes field studies of the effectiveness of portable air cleaners. Over 500 papers were considered, and 148 were reviewed in detail, to extract 35 specific research results (e.g., particulate removal performance) or characteristics (e.g., type of building). These were aggregated to provide an overview of results and approaches to this type of research, and to provide meta-analyses of the results. The review includes: descriptions of the geographical location of the research; rate of publications over time; types of buildings and occupants in the field study; types of air cleaner technology being tested; pollutants being measured; resulting pollutant removal effectiveness; patterns of usage and potential barriers to usage by occupants; and the potential for by-product emissions in some air cleaner technologies. An example result is that 83 of the 148 papers measured reductions in fine particulates (PM 2.5 ) and found a mean reduction of 49 % with standard deviation of 20 %. The aggregated results were approximately normally distributed, ranging from finding no significant reduction up to a maximum above 90 % reduction. Sixteen of the 148 papers considered gaseous pollutants, such as volatile organic compounds, nitrogen dioxide, and ozone; 36 papers considered biological pollutants, such as bacteria, viruses, pollen, fungi, etc. An important challenge, common to several studies, is that occupants run the air cleaners for shorter periods and on low airflow rate settings, because of concerns about noise, drafts, and electricity cost, which significantly reduces air cleaning effectiveness., Competing Interests: Declaration of competing interest Amir Ebrahimifakhar is a current employee, and Yu Luo is a former employee of Delos Living LLC, a wellness real estate and technology company that, among other things, sells portable air cleaners. None of the research reported in this paper involved any air cleaners marketed or sold by Delos. The remaining authors have no conflicts of interest to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)

High-performance biomass materials with good thermal insulation, flame retardrancy, and mechanical properties are urgently required for thermal management. Herein, a novel lignocellulose aerogel treated using a recyclable deep eutectic solvent (DES) was physically mixed with tourmaline particles (TPs) to enhance its structural stability, flame retardancy, and mechanical properties. The optimized TPs-modified lignocellulose aerogel (TLA-4) had good comprehensive performances due to the synergistic effect of ammonium sulfate and TPs. Compared with TPs-free lignocellulose aerogel (LA), the total heat release (THR) and heat release rate (HRR) of TLA-4 were reduced by 62.0 % and 66.3 %, respectively, and the limiting oxygen index (LOI) of TLA-4 was drastically enhanced by 74.1 %. TLA-4 also exhibited a low thermal conductivity of 29.67 mW/mK, showing favorable thermal insulation performance. When compressed to 5 %, the mechanical strength of TLA-4 increased by 8.3 times. Meanwhile, the presence of TPs and abundant pores in the aerogel contributed to the release of negative oxygen ions (NOIs), aiding air purification. A life cycle assessment (LCA) indicated that this composite had a minimal environmental impact (EI) in 17 categories compared to other similar aerogels. The proposed strategy for preparing an environment-friendly lignocellulose aerogel offers significant potential for applications in home decoration and building materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The application of natural small molecule (NSM) in electrospun fibers is the key to achieving powerful functionality and sustainable development. However, the lack of understanding regarding the mechanism for loading NSM hinders the advancement of high-performance functional fibers. This work clarified the loading mechanism of NSM in polymer solution by comparing the different behaviors of curcumin (Cur), phloretin (PL), and tea polyphenols (TP) blended ethyl cellulose (EC) solutions. We found that TP may lead to the folding of polymer chains due to its strongest hydrogen bond, which in turn promoted the dispersion of TP along the polymer chain. Therefore, TP could achieve good electrospinnability at the highest loading capacity (16 times the Cur and 4 times the PL). Finally, chitosan was introduced into EC/TP to prepare tree-like nanofibers, achieving high-performance antibacterial air filtration. The filtration efficiency for 0.3 μm NaCl particles, pressure drop, and quality factor were 99.991 %, 85.5 Pa, and 0.1089 Pa -1 , respectively. The bacteriostatic rates against Escherichia coli and Staphylococcus aureus were all 99.99 %. This work will promote the application of NSM and the developments of multifunctional electrospun fibers and high-performance air filters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Copyright of Jurnal Teknosains is the property of Sekolah Pascasarjana Universitas Gadjah Mada and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, the development of the Internet of Vehicles (IoV) has led to an increase in the demand for data sharing services for the IoV. In the era of big data, safe and convenient data sharing services for IoV are inseparable from the support of reliable data. With the increase in the number of smart cars, how to filter the data provided by vehicles while protecting privacy to improve the quality of data sharing services has attracted the attention of scholars. However, in the existing data sharing scheme for IoV, the vehicles that provide data are selected based on the reputation mechanism or the voting mechanism. Our analysis shows that these two mechanisms lack objectivity and are vulnerable to cooperative attack. Therefore, based on spatiotemporal matching, a new trusted relationship establishment method, this paper proposes an objective and cooperative attack-resistant vehicle selection scheme for data sharing in IoV. Bloom filters and an exponential ElGamal encryption scheme are used to implement private set intersection cardinality (PSI-CA) technology for evaluating spatiotemporal matching level. In this paper, the scheme proposed is of great significance to improve existing vehicle services and improve driving safety. [ABSTRACT FROM AUTHOR]

In this paper, we propose a sea current relative navigation method using an interacting multiple model (IMM) filter with adaptive fading technique that can compensate an inaccurate sea current dynamics model. Due to the marine environment, the underwater vehicles largely depend on inertial navigation. Unfortunately, since its performance deteriorates with time, it is usually aided by another sensor. An electromagnetic-log (EM-log) and a Doppler velocity log (DVL), which are mainly used in marine navigation, provide relative velocity measurements to the sea currents, and hence require an accurate sea current dynamics model to fully utilise them. However, it is difficult to reflect the actual sea current changes with just a single fixed model, resulting in degraded overall navigation performance. Therefore, this paper proposes an IMM filter that can use multiple sea current dynamics models and has sub-filters designed with adaptive fading extended Kalman filter (AFEKF) to compensate for the mismodelling of sea current dynamics. The method is verified by simulation and shows a performance improvement comparable to the optimal filter. [ABSTRACT FROM AUTHOR]

This document is a response to a letter regarding a recently published paper titled "Effectiveness of Asthma Home Management Manual and Low-Cost Air Filter on Quality of Life Among Asthma Adults: A 3-Arm Randomized Controlled Trial." The authors address concerns raised by the letter writer and explain their choices in the study design and analysis. They acknowledge that some keywords may not strictly adhere to MeSH guidelines but defend their inclusion based on their relevance to the research. The authors also discuss the impact of asthma duration on the study results and clarify that certain data were considered baseline rather than outcome measures. The authors report no conflicts of interest. [Extracted from the article]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted human-to-human via aerosols and air-borne droplets. Therefore, capturing and destroying viruses from indoor premises are essential to reduce the probability of human exposure and virus transmission. While the heating, ventilation, and air conditioning (HVAC) systems help in reducing the indoor viral load, a targeted approach is required to effectively remove SARS-CoV-2 from indoor air to address human exposure concerns. The present study demonstrates efficient trapping and destruction of SARS-CoV-2 via nano-enabled filter technology using the UV-A-stimulated photoelectrochemical oxidation (PECO) process. Aerosols containing SARS-CoV-2 were generated by nebulization inside an air-controlled test chamber where an air purifier (Air Mini+) was placed. The study demonstrated the efficient removal of SARS-CoV-2 (99.98 %) from the test chamber in less than two minutes and PECO-assisted destruction (over 99%) on the filtration media in 1 h. Furthermore, in a real-world scenario, the Molekule Air-Pro air purifier removed SARS-CoV-2 (a negative RT-qPCR result post-running the filter device) from the circulating air in a COVID-19 testing facility. Overall, the ability of two FDA-approved class II medical devices, Molekule Air-Mini+ and Air-Pro air purifiers, to remove and destroy SARS-CoV-2 in indoor settings was successfully demonstrated. The study indicates that as the "tripledemic" of COVID-19, influenza, and respiratory syncytial virus (RSV) overwhelm the healthcare facilities in the USA, the use of a portable air filtration device will help contain the spread of the viruses in close door facilities, such as in schools and daycare facilities., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The ventilation rate of cigarettes is an important indicator that affects the internal quality of cigarettes. When producing cigarettes, the unit may experience unstable ventilation rates, which can lead to a decrease in cigarette quality and pose certain risks to smokers. By establishing the ventilation rate prediction model, guide the design of unit parameters in advance, to achieve the goal of stabilizing unit ventilation rate, improve the stability of cigarette ventilation rate, and enhance the quality of cigarettes. This paper used multiple linear regression networks (MLR), backpropagation neural networks (BPNN), and genetic algorithm-optimized backpropagation (GABP) to construct a model for the prediction of cigarette ventilation rate. The model results indicated that the total ventilation rate was significantly positively correlated with weight (P < 0.01), circumference, hardness, filter air permeability, and open resistance. The results showed that the MLR models' (RMSE = 0.652, R2 = 0.841) and the BPNN models' (RMSE = 0.640, R2 = 0.847) prediction ability were limited. Optimization by genetic algorithm, GABP models were generated and exhibited a little better prediction performance (RMSE = 0.606, R2 = 0.873). The results indicated that the GABP model has the highest accuracy in the prediction of predicting ventilation rate and can accurately predict cigarette ventilation rate. This method can provide theoretical guidance and technical support for the stability study of the ventilation rate of the unit, improve the design and manufacturing capabilities and product quality of short cigarette products, and help to improve the quality of cigarettes. [ABSTRACT FROM AUTHOR]