Simple Filtering Method Research Articles

High-efficiency oil/water separation by simple fabrication of superhydrophobic nanocomposite (Zno-SiO2) coating mesh

Environmental sustainability and human health are globally imperilled by oil-contaminated water resulting from oil spill disasters or industrial disposal. Superhydrophobic materials have gained increasing attention in oil–water separation to fulfil the ever-growing need for highly effective oil–water separation. Due to the regeneration ability of silicon dioxide nanoparticles (SiO2), superhydrophobic/superolephilic nanocomposite (ZnO-SiO2) was created using a new, simple flame treatment procedure. ZnO(NRs) was coated on stainless steel mesh via water bath deposition method and modified with silicon rubber ( RTV-SR) solution. The mesh coated exhibited an excellent superhydrophobic surface with water at a contact angle 168±1°, a sliding angle 3.5° and superolephilic with oil contact angle OCA (0°). The x-ray diffraction, contact angle measurement, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectroscopy (EDS) were used to describe the coated mesh surface. Kerosene-water, diesel oil–water mixtures and sunflower oil–water are successfully separated by the simple filtering method using the coated mesh with a separation efficiency of 96%.

Global Distributions of Tropospheric and Stratospheric Gravity Wave Momentum Fluxes Resolved by the 9-km ECMWF Experiments

Abstract Based on 20-day control forecasts by the 9-km Integrated Forecasting System (IFS) at the European Centre for Medium-Range Weather Forecasts (ECMWF) for selected periods of summer and winter events, this study investigates global distributions of gravity wave momentum fluxes resolved by the highest-resolution-ever global operational numerical weather prediction model. Two supplementary datasets, including 18-km ECMWF IFS experiments and the 30-km ERA5, are included for comparison. In the stratosphere, there is a clear dominance of westward momentum fluxes over the winter extratropics with strong baroclinic instability, while eastward momentum fluxes are found in the summer tropics. However, meridional momentum fluxes, locally as important as the above zonal counterpart, show different behaviors of global distribution characteristics, with northward and southward momentum fluxes alternating with each other especially at lower altitudes. Both events illustrate conclusive evidence that stronger stratospheric fluxes are found in the ECMWF forecast with finer resolution, and that ERA5 datasets have the weakest signals in general, regardless of whether regridding is applied. In the troposphere, probability distributions of vertical motion perturbations are highly asymmetric with more strong positive signals especially over latitudes covering heavy rainfall, likely caused by convective forcing. With the aid of precipitation accumulation, a simple filtering method is proposed in an attempt to eliminate those tropospheric asymmetries by convective forcing, before calculating tropospheric wave-induced fluxes. Furthermore, this research demonstrates promising findings that the proposed filtering method could help in reducing the potential uncertainties with respect to estimating tropospheric wave-induced fluxes. Finally, absolute momentum flux distributions with proposed approaches are presented, for further assessment in the future.

Separation of oil-water via porous PMMA/SiO2 nanoparticles superhydrophobic surface

A porous superhydrophobic coating on filter paper is developed by employing solution-casting technique using polymethyl methacrylate-co-ethyl acrylate polymer (PMMA) and silica nanoparticles (SiO2). The wettability, surface topography and chemical composition of coating were examined. The coated filter paper shows a static water contact angle of 170° ± 2° and sliding angle of 8° ± 1°. Additionally, thermal stability by annealing at different temperature ranging 40–280 °C, UV stability, chemical stability by immersing in different solutions of pH range of 2–13, and mechanical durability by performing adhesive tape peeling, sand abrasion, and washing tests of coatings were evaluated. Petroleum ether – water mixture and emulsion were successfully separated via a simple filtering method by using coated filter paper with high separation efficiency. Furthermore, coating also exhibits the excellent self-cleaning property. This coating can apply for any size and shape of the filter papers and has tremendous industrial applications.

Solvent‐free mechanical extraction of Opuntia ficus‐indica mucilage

AbstractThe performance of solvent‐free extraction methods used for obtaining mucilage powder from Opuntia ficus‐indica has been evaluated in terms of yield, energy‐drawn, and the rheological parameters as well as its rheological properties and content of polysaccharides. Three different methods based on mechanical extraction were investigated, namely the simple filtering method (SFM), the filtering‐clarifying‐concentrating method (FCCM), and the filtering‐concentrating method (FCM). The SFM method consisted of obtaining the mucilage powder by spray‐drying the filtered cactus juice. For the second method (FCCM), the mucilage powder was obtained by drying the filtered, clarified, and concentrated (evaporation by boiling for the elimination of part of the water) cactus juices, while for the FCM method the filtered juice was concentrated and dried. The highest mucilage yield was obtained with the SFM method, while the highest consistency, in terms of viscosity combined with the lowest energy requirement was obtained when using the FCM method. The polysaccharide spectrum characterization was carried out by Nuclear Magnetic Resonance (NMR) Spectroscopy. Spectra obtained from the different extraction processes indicate the presence of mixtures of polysaccharides such as unesterified rhamnose, xylose, mannose, and galacturonic acid. Remarkably, rhamnose is the most abundant in two of the three extracts, although almost 50% of the concentration of galacturonic acid present in the three extracts is unesterified.Practical applicationsAt the present time, several authors focused on obtaining mucilage from Opuntia ficus‐indica for the food and pharmaceutical industries by precipitation with solvents, such as acetone or alcohols, with low yields and high production cost, due to high consumption of the organic solvents and long extraction time. While this kind of mucilage may be suitable for foodstuff processing, it must be demonstrated that do not contain a toxicologically dangerous amount, the process of extraction was under good manufacturing practices as well as it is necessary to verify that this mucilage meets the specific purity criteria provided by the application. This involves conducting quantitative analysis that is usually costly and time‐consuming. Therefore, a study on mechanical extraction process has been performed in order to have a Generally Recognized as Safe (GRAS) cactus mucilage. The process developed is a mechanical extraction of low cost, suitable to obtain mucilage at large‐scale, with high yield, low energy requirements, and no solvents involved. The mucilage obtained is a safe powder useful as additive in food processing such as dispersing agent avoiding sedimentation in vegetable protein suspensions for patients with malnourishment.

Angle-stack reverse time migration in VTI media

Seismic anisotropy is widespread in real media, the conventional isotropic reverse time migration method will lead to problems such as inaccurate depth and unfocused energy in dealing with the anisotropic issues, and low frequency noise with strong amplitude in imaging results can not be completely removed by simple filtering method such as Laplace filter operator. To solve these problems, we have researched pseudo acoustic equation to simulate qP wave propagation in anisotropic VTI media and used the smoothed isotropy or elliptic anisotropy tapered circular region located in source points to suppress the qSV wave. On this basis, we also develop angle-stack reverse time migration method in VTI media, which stacks the imaging results in angle domain to suppress low-frequency noise and improve imaging accuracy. Model test and application example prove that this method can obtain accurate imaging results with balanced energy in steep dip structures, and has better effect in suppressing low-frequency imaging noise.

Large areal mass, flexible and freestanding polyaniline/bacterial cellulose/graphene film for high-performance supercapacitors

Flexible and freestanding electrodes with high mass loading in the range of 7–13 mg cm−2 made of polyaniline (PANI)/bacterial cellulose (BC)/graphene (GN) conductive paper through a simple filtering method.

Durable superhydrophobic/superoleophilic epoxy/attapulgite nanocomposite coatings for oil/water separation

To improve the durability of oil/water separation materials, the superhydrophobic/superoleophilic epoxy/attapulgite nanocomposite coatings on the stainless steel meshes for oil/water separation were fabricated via a facile spray-coating method. The surface microstructure and wettability of the coated mesh were closely related to the attapulgite content. At the attapulgite content of 44.4wt%, the coated mesh exhibited superhydrophobicity with the water contact angle of 160±1° and superoleophilicity with the oil contact angle of 0°, which caused water to run off the mesh while allowing oil to permeate through. Various oil/water mixtures, such as hexadecane/water mixture, lubrication oil/water mixture, and paroline/water mixture, can be successfully separated by a simple filtering method using the coated mesh with the separation efficiency above 98%. This gravity-driven oil/water separation using the coated mesh was simple, time saving, and repeatable for at least 30 times. Most importantly, after being treated in various harsh conditions, including mechanical scratch, high temperature, humid atmospheres, and corrosive substance, the coated mesh still maintained highly efficiency for oil/water separation. The advantages of scalable production, high efficiency, and excellent durability for the epoxy/attapulgite coating make it to be a good candidate for oil/water separation in practical applications.

Estimating Scene-Oriented Pseudo Depth With Pictorial Depth Cues

Estimating depth information from a single image has recently attracted great attention in 3D-TV applications, such as 2D-to-3D conversion owing to an insufficient supply of 3-D contents. In this paper, we present a new framework for estimating depth from a single image via scene classification techniques. Our goal is to produce perceptually reasonable depth for human viewers; we refer to this as pesudo depth estimation. Since the human visual system highly relies on structural information and salient objects in understanding scenes, we propose a framework that combines two depth maps: initial pseudo depth map (PDM) and focus depth map. We use machine learning based scene classification to classify the image into one of two classes, namely, object-view and non-object-view. The initial PDM is estimated by segmenting salient objects (in the case of object-view) and by analyzing scene structures (in the case of non-object-view). The focus blur is locally measured to improve the initial PDM. Two depth maps are combined, and a simple filtering method is employed to generate the final PDM. Simulation results show that the proposed method outperforms other state-of-the-art approaches for depth estimation in 2D-to-3D conversion, both quantitatively and qualitatively. Furthermore, we discuss how the proposed method can effectively be extended to image sequences by employing depth propagation techniques.

Thermolysis of scrap tire using supercritical toluene

With toluene in the supercritical state, scrap tire was decomposed into low molecular weight hydrocarbon liquid and solid residual. The experiment was carried out at 523.15, 573.15 and 623.15 K and pressures of 5, 10, and 15 MPa. The liquid and solid residual products were further separated by a simple filtering method. The reaction time, tire weight and the amount of the solvent were determined for the optimal thermolysis. The decomposition percent and TGA were used to evaluate the decomposition characteristics in terms of temperature and pressure. The GC-MS was applied to the decomposed liquid products from the various conditions. The average molecular weight of the decomposed liquid products tended to become lower with the increasing temperature.

Some statistical methods for analyzing the TOMS data

This paper investigates variations in both space and time of total column ozone through the Nimbus 7 Version 7 Total Ozone Mapping Spectrometer (TOMS) data. While the gridded daily TOMS dataset has high spatial and temporal resolution, the asynoptic nature of the data and artifacts in the observations make it difficult to use at the available level of resolution. In the past, only subsamples or averages over both space and/or time of the TOMS data have been subjected to statistical analysis. This work discusses three ways of modeling the space‐time structure of the TOMS data. We conclude that a representation in which the datapoints at a fixed latitude are treated as if they were on a line in the longitude‐time plane is the best. At each grid point, the total column ozone field is partitioned into a 31 day moving average and a remainder or residual ozone field. For a fixed latitude and a fixed season, the residual field can be reasonably modeled as a stationary random process with mean zero. The sample correlation functions are calculated for 52 seasons over 13 years and 7 latitudes. Comparing these correlation functions and their associated periodograms across seasons, years, and latitudes provides a useful means for discerning patterns in the TOMS data. For example, the correlation functions show that at latitudes around the equator, the apparent movement of ozone is from east to west, and at higher latitudes, the movement is from west to east. In addition, the movement is more strongly from west to east in the southern hemisphere than in the northern hemisphere. Periodograms for latitudes near the equator show clear evidence of a scan‐angle effect noted by others. However, our analysis demonstrates that the scan‐angle effect shows up at frequencies other than the orbital frequencies and its harmonics. We suggest a simple filtering method for removing most of this artifactual effect.

Artificial texturing

Texture is an important surface characteristic which provides a great deal of information about the nature of a surface, and several computationally complex algorithms have been implemented to replicate realistic textures in computer shaded images. Perceptual psychologists have recognized the importance of surface texture as a cue to space perception, and have attempted to delineate which factors provide primary shape information. A rendering algorithm is presented which uses these factors to produce a texture specifically designed to aid visualization. Since the texture is not attempting to replicate an actual texture pattern, it is called “artificial” texturing. This algorithm avoids the computational limitations of other methods because this “artificial” approach does not require complex mappings from a defined texture space to the transformed image to be rendered. A simple filtering method is presented to avoid unacceptable aliasing.