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Total variation (TV) regularization model has the excellent performance in noise-removing and edge-preserving. However, it often yields staircase artifacts in the smooth region of the restorations. To attack this problem, we propose a generalized hybrid nonconvex variational regularization model in this paper, which utilizes two nonconvex regularizers to impose the priors to the two different components of the images, respectively. One is nonconvex TV regularizer that measures the piecewise constant component of the input image, and the other is nonconvex Laplacian regularizer that models the piecewise smooth component. New model inherits the advantages of the nonconvex regularization and the first- and second-order hybrid variational regularization, which can well remove the noises while preserving edges and reducing staircase artifacts. To solve this nonconvex minimization problem efficiently, we propose a first-order algorithm based on alternating direction method of multipliers (ADMM) combining with majorization–minimization (MM) scheme. In addition, a sufficient condition for the convergence of the proposed algorithm is provided. In the experiments, we compare the proposed model with several state-of-the-art image denoising models, numerical results illustrate the effectiveness of the proposed model and algorithm for both synthetic and real images in terms of peak signal to noise ratio (PSNR) and structural similarity (SSIM) indexes.

This work aims to investigate the changes in the shear and oscillation responses of an ethoxylated alkylamine emulsion with the addition of acetic acid and establishes their relationships with the emulsion phase inversion. The initial emulsion behaves as a non-Newtonian fluid exhibiting shear thinning with a viscoelastic gel structure (at rest). Upon the addition of acetic acid, the emulsion first transforms to a structureless (at rest) non-Newtonian fluid with lower viscosity and worse shear thinning compared with the initial state and then converts back to a non-Newtonian fluid with a higher gel strength, higher elasticity (at rest) and better shear thinning than the initial state as the phase inversion proceeds from an oil-continuous stage to a bicontinuous stage. This regained non-Newtonian character can be maintained throughout the whole bicontinuous stage and can even extend to the beginning of the water-continuous stage which is obtained from the bicontinuous stage by increasing the acetic acid content; however, it is ultimately replaced by a structureless (at rest) non-Newtonian fluid that exhibits lower viscosity and worse shear thinning compared with the initial state as the acetic acid content increases. The establishment of relationships among the interfacial moduli and deformation, geometrical factors (i.e., interfacial curvature, droplet shape and size and positional structure) and the liquid crystal phase behaviors help to elucidate the mechanisms that control the rheological transitions of emulsions. Based on these results, a novel water-washable viscoelastic emulsion drilling fluid is proposed.

Catering oil fumes are a major hazard to human health. In particular, the typical Chinese cooking style is characterised by a high temperature frying process that produces high levels of cooking oil fumes. However, limited data relating to this sector mean that national emission inventory data specific to the catering service industry do not exist. To address above deficiency and thus to establish the inventory of a city, or a province, or even a country, a door-to-door survey campaign was launched in the Chinese cities of Heze and Linfen to determine the structure of local catering industries. Data revealed that the number of catering businesses per 104 people was 17 ± 4. Of these, 3.0 ± 1.4, 15.0 ± 1.4, and 82.0 ± 0.0% were classified as large, medium, and small enterprises, respectively. Furthermore, the installation rates of fume purifiers were 74 ± 13, 66 ± 9, and 51 ± 14% for large, medium, and small enterprises, respectively, with net removal efficiencies of 63 ± 11, 50 ± 7, and 31 ± 8%, respectively. This information was extrapolated across all provincial regions of China to construct a provincial and national emission inventory. In 2017, China's national catering industry released approximately 34 kt of volatile organic compounds (VOCs), 38 kt of particulate matter with a diameter less than 2.5 μm (PM2.5), 48 kt of particulate matter with a diameter less than 10 μm (PM10), 1 kt of black carbon (BC), and 27 kt of organic carbon (OC). A significant correlation was observed between vegetable oil consumption and emissions (e.g., for VOCs, y = 14.94 x + 76.50, R2 = 0.87, where y is VOCs emissions and x is vegetable oil consumption), indirectly corroborating the rationality of the inventory. Moreover, this correlation provides the potential for a dynamic inventory based on vegetable oil consumption. Future studies are proposed to address more influential factors to improve the reliability of the national inventory and refer to big data, rather than door-to-door investigation, to identify the amount of catering service businesses in a region.

Shale hydration is the main cause of wellbore instability during drilling using water-based drilling fluids (WBD). In this work, NH2- and HO-functionalized ionic liquids (ILs) were investigated for their performances on inhibiting the shale hydration, as well as their influences on the properties of WBD, using immersion and sedimentation tests, linear swelling test, hot-rolling dispersion test, rheological and filtration experiments. The mechanisms were identified by X-ray diffraction (XRD), zeta-potential and particle size distribution analyses, scanning electron microscopy (SEM) and related theoretical analysis. Evaluation experiment results showed that the NH2-functionalized IL had the best inhibition performance, followed by poly(propylene glycol)bis(2-aminopropyl ether), HO-functionalized IL and KCl. NH2-functionality was more favorable to shale inhibition than HO-functionality. When used in WBD, ILs could prevent viscosity building-up at high temperature, but cause filtration and inhibition failure, which could be mitigated when polyanionic cellulose (PAC) was added in WBD prior to inhibitors. Three critical observations helped elucidate the inhibitive mechanisms: the intercalation of cationic groups of ILs into the clay interlayers, the decrease of both interlayer spacing and double layer thickness. The NH2-functionalized IL allowed the smallest interlayer spacing and double layer thickness and therefore performed best in inhibition. The inhibition failure in WBD with ILs depended on two aspects: the consumption of ILs untimely and the filtration failure of WBD. PAC could decrease both of ILs’ loss within WBD and water loss toward shale, mitigating the WBD’s inhibition failure. Our work will facilitate the rational design of efficient and environmentally acceptable inhibitors and their rational applications in WBD for drilling shale formation.

In this paper, the inhibition property of polyethyleneimine (PEI) in drilling fluid was studied. The inhibition property was evaluated by linear swell test and roll recovery. The addition of PEI70000 resulted in the lowest swelling height, compared with the others inhibitor. Especially PEI was environmental and friendly. The inhibition mechanism was investigated by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Scanning electron microscopy, Zeta potential and Surface area analyzer. The negative charge in the surface of montmorillonite (Mt) was neutralized by the positive charge of PEI. PEI was adsorbed in the surface of Mt and intercalated into the interlayer of Mt, which reduced the hydration repulsion of diffuse electric double layer and leaded to inhibit the hydration of clay. Hydrogen bonding between amino groups in PEI and hydroxyl in the surface of Mt can be formed in the process. The coordination of electrostatic interaction and hydrogen bonding presented water molecules from the interlayer space of Mt, which resulted from the adsorption and intercalation of PEI in the surface and interlayer space of Mt. There was an amount of nitrogen in the backbone and side of PEI, leading to more positive ion than chitosan quaternary ammonium salt (HTCC). The more positive ion resulted in the stronger force between inhibitor and clay due to the protonation of nitrogen in water. The molecular weight of PEI has great influence on inhibition property. The larger molecular weight of PEI performed the better inhibition property except for PEI1800. Indicating the molecular weight of PEI was not the sole factor to control the inhibition property. What was more, the larger molecular weight of PEI leaded to the worse water-solubility.

Clay is closely associated with the drilling of oil and gas by influencing the shale wellbore stability and the rheology of drilling fluids. In this work, four imidazolium-based ionic liquids (ILs) were used to modify the typical clay (i.e., sodium bentonite (Na-Bent)), and their effects on the Na-Bent rheological and swelling properties were evaluated by shear rheological measurements, immersion experiment, linear swelling measurements. The mechanisms involved were identified by using fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Zeta-potential and environmental scanning electron microscopy (ESEM) analysis. Evaluation experiment results showed that the adsorption of each IL could both significantly affect the Na-Bent rheological property and inhibit the Na-Bent swelling, which strongly depended on ILs' structures and concentrations. The mechanism study revealed that the cationic groups of ILs could adsorb on Na-Bent prior to water molecules, followed by expelling water and compressing the double electrode layers, and therefore inhibit the Na-Bent swelling. The adsorption of ILs could also change aggregation behaviors of the Na-Bent particles, by which the “house of cards” structures in Na-Bent dispersions were improved or destroyed, resulting in changes in rheological properties of Na-Bent dispersions.