Deep Removal Research Articles

Deep Neural Network-Based Removal of a Decaying DC Offset in Less Than One Cycle for Digital Relaying

To make a correct decision during normal and transient states, the signal processing for relay protection must be completed and designated the correct task within the shortest given duration. This paper proposes to solve a dc offset fault current phasor with harmonics and noise based on a Deep Neural Network (DNN) autoencoder stack. The size of the data window was reduced to less than one cycle to ensure that the correct offset is rapidly computed. The effects of different numbers of the data samples per cycle are discussed. The simulations revealed that the DNN autoencoder stack reduced the size of the data window to approximately 90% of a cycle waveform, and that DNN performance accuracy depended on the number of samples per cycle (32, 64, or 128) and the training dataset used. The fewer the samples per cycle of the training dataset, the more training was required. After training using an adequate dataset, the delay in the correct magnitude prediction was better than that of the partial sums (PSs) method without an additional filter. Similarly, the proposed DNN outperformed the DNN-based full decay cycle dc offset in the case of converging time. Taking advantage of the smaller DNN size and rapid converging time, the proposed DNN could be launched for real-time relay protection and centralized backup protection.

Dynamic Study on Vanadium Extraction Process in Basic Oxygen Furnance: Modeling Based on Gibbs’ Free Energy Minimization

Vanadium extraction process demands low residual vanadium and carbon loss, and variations of dissolved elements in hot metal must be determined to achieve it. A three parts dynamic model that applies the concept of Gibbs’ free energy minimization at the slag–metal interface is proposed. Modeling simulation results shows good uniformity with plant experimental data, and the presented model can describe the vanadium extraction process in BOF qualitatively well. The effects of coolant addition and oxygen flow rate have been studied by modeling. The lack of coolant will reduce (FeO) content and elevate the molten bath temperature, which are harmful to deep vanadium removal with less carbon loss in semi-steel. The excessive oxygen flow rate has little effect on residual [V], and there is more carbon loss because of higher (FeO) content and molten bath temperature.

Purification of Micro-Polluted Lake Water by Biofortification of Vertical Subsurface Flow Constructed Wetlands in Low-Temperature Season

In this study, a novel lab-scale biofortification-combination system (BCS) of Oenanthe javanica and Bacillus series was developed to improve the treatment ability of vertical subsurface flow constructed wetlands (VSFCW) at low temperatures (0–10 °C). The results showed that BCS-VSFCW overcame the adverse effects of low temperature and achieved the deep removal of nutrients. In addition, the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) by BCS-VSFCW were 38.65%, 28.20%, 18.82%, and 14.57% higher than those of blank control, respectively. During the experiment, Oenanthe javanica and low temperature tolerant Bacillus complemented each other in terms of microbial activity and plant uptake. Therefore, VSFCW combined with Oenanthe javanica and low temperature tolerant Bacillus has a promising future in low temperature (<10 °C) areas of northern China.

An integrated separation technology for high fluoride-containing wastewater treatment: Fluoride removal, membrane fouling behavior and control

The high concentration of fluoride in aqueous, which exacerbated by the discharged wastewater from semiconductor, electroplating, metallurgical and ceramics industries, has gone far beyond the World Health Organization (WHO) standard and seriously affected the health of human life. This study aims to validate the deep removal of fluoride from high fluoride-containing wastewater by using an integrated precipitation/crystallization/ultrafiltration (UF)/reverse osmosis (RO) system. The system enables an extremely low residual fluoride concentration (down to 0.25 mg L−1) qualified WHO standard, which was much lower than those of other reported membrane-based processes. In particular, the application of crystallization rather than conventional coagulation/flocculation was demonstrated to be effective in reducing fluoride, turbidity and sludge water content. Membrane fouling analysis indicated that UF membrane scaling was attributed to the CaF2 particles deposition at recovery rates of 70%–90%. RO membrane fouling behaviors were identified at recovery rate of 50% (organic fouling), 70% (inorganic scaling occurred and organic fouling) and 80% (inorganic scaling and organic fouling). Meanwhile, UF/RO membrane scaling/fouling could be removed by pure water cleaning (UF) and Na2CO3/NaOH/HCl cleaning (RO). Results of this work shall provide useful information on the application of a precipitation/crystallization/UF/RO system to purify and recover high fluoride-containing wastewater.

Mainstream nitritation and denitritation in a pilot-scale multi-cycle sequencing batch reactor

Addition of external carbon sources for deep nitrogen removal highly increased the cost of municipal wastewater treatment. In this study, a carbon-saving nitritation and denitritation process was developed in a pilot-scale multi-cycle sequential batch reactor over 230 days. In the first three stages, the effluent total nitrogen (TN) concentration of the pilot plant without external carbon addition was similar to that of the on-site cyclic activated sludge system with external carbon addition. A highest nitrite accumulation rate (57.3%) and TN removal rate (85.1%) was observed, respectively, under conditions that temperature of 28.3 °C, dissolved oxygen concentrations of 2.0 mg/L and COD/N ratios of 4.5:1 as well as a short oxic phase (32.8 min). As the influent TN decreased after heavy rain, NOB could still be suppressed by shortening oxic phase and lowering DO (1.5 mg/L). In winter, slight nitrite accumulation was still obtained by adding glucose in stage IV. Nitrite competition between NOB and denitrifiers was indeed the key to NOB suppression. It should be a good choice for wastewater treatment plants to achieve high discharge standard and save carbon source using such a proposed process.

Enhancing nitrate removal efficiency of micro-sized zero-valent iron by chitosan gel balls encapsulating

The activity of micro-sized zero-valent iron (MZVI) material for nitrate removal in neutral pH and low C/N ratios water needs to be improved. In this study, micro-sized zero-valent iron@chitosan (MZVI@CS) material was synthesized through embedding MZVI particles into chitosan (CS) gel by sol-gel method, and was used for deep removal of NO3−-N in the absence of organic carbon sources and neutral pH. The NO3−-N removal rate of MZVI@CS was 0.37 mg-N·L−1·d−1 (dosage of 1%, initial pH = 7, 25 °C, initial nitrate concentration = 15 mg-N·L−1), which was 11.33 times higher than that of MZVI. The apparent activation energy (Ea) of MZVI@CS with nitrate was 38.23 kJ·mol−1. MZVI@CS can remove nitrate effectively at a low concentration (15 mg-N·L−1). A stable denitration rate (0.37–2.28 mg-N·L−1·d−1) could be maintained under weak acidic, neutral and alkaline conditions (pH = 5–9). More than 80% of reduced nitrate was converted to N2, and only a small amount was converted to NH4+ or NO2−. The gel structure of MZVI@CS eliminated the agglomeration between MZVI particles while the forming of Fe-CS chelates reduced the formation of iron oxide and solved the problems of passivation, hence successfully strengthened the NO3−-N removal efficiency of MZVI. Therefore MZVI@CS has great application potential in NO3−-N deep removal of water bodies with neutral pH and low C/N ratios.

Catalytic adsorptive desulfurization of mercaptan, sulfide and disulfide using bifunctional Ti-based adsorbent for ultra-clean oil

Ultra-deep desulfurization of transformer oil is of great demand among power industry. In this work, the effective and deep removal of various types of organosulfurs, including mercaptan, sulfide and disulfide via catalytic adsorptive desulfurization (CADS) using bifunctional Ti-based adsorbent is reported. Compared to adsorptive desulfurization (ADS), dramatically improvement of the organosulfur uptakes were achieved under CADS process. The equilibrium adsorption capacity at 5 μg∙g −1 S reached up to 15.7, 33.4, 11.6 and 11.9 mg∙g −1 for propyl mercaptan( n -PM), dimethyl sulfide(DMS), di- t -butyl disulfide (DTBDS) and dibenzyl disulfide (DBDS), which was 262, 477, 97 and 128 times to that of ADS process, respectively, and was the highest among the reported desulfurization adsorbents. Moreover, it achieved superior breakthrough capacity of 2050, 530 and 210 ml F·(g A) −1 at the breakthrough S concentration of 1 μg∙g −1 of the commercial transformer oil S containing 10, 50 and 150 μg∙g −1 , respectively. The effectiveness of CADS is associated to the transformation of sulfur species to higher polar sulfonic species with the assistance of mild oxidant, which can be readily captured by silanol groups on SiO 2 through H-bonding interaction. The excellent recyclability of the adsorbent can be realized through solvent washing or oxidative air treatment. This work provides an effective and economic approach for the elimination of trace amount of mercaptan, sulfide and disulfide from transformer oil.

Novel process for deep removal of chlorine and recycling of chlorinated tailings from titanium-bearing blast-furnace slag

Given the high chloride ion content in chlorinated tailings that harm the surrounding environment cannot be directly utilized, a new process for the deep removal of chloride ions from chlorinated tailings with additives was proposed. The products obtained included tailing slag, which can be used as a building material, and salt, which can be used in industry. Theoretical calculations and experiments were performed to determine the feasibility of the new process. The results showed that the chloride ions from the chlorinated tailings and sodium ions from the additives formed NaCl, which could be removed during water leaching. NaOH served as a better additive than sodium sulfate. An increase in the molar ratio and the prolongation of ball-milling was beneficial for the dechlorination of the water leaching residue. An increase in the roasting temperature leads to an increase in particle size, which worsens the kinetics of subsequent leaching and reduces the leaching rate. The developed process can obtain tailings with chloride ion content of less than 0.1%, which meets the standard for building materials applications. Meanwhile, NaCl with a purity greater than 99% could be obtained, preventing chloride ion pollution of water resources and the comprehensive utilization of chlorinated tailing.

Effects of Mn(II) addition on Cd(II) removal by hydrated manganese dioxide.

In this study, the redox homogeneous precipitation method was applied to synthesize hydrated manganese dioxide (HMO) and to study the removal performance of Cd(II) from wastewater. Moreover, a small amount of Mn(II) could still combine with HMO without causing the desorption of Cd(II). A novel discovery was that the synergistic effect of KMnO4 and Mn(II) could directly regenerate MnO2 to deeply remove Cd(II), realizing the recycling of MnO2. The influence of Mn(II) addition on the adsorption behavior of Cd(II) was discussed in terms of pH, Mn(II) addition mode, initial concentration of Mn(II) or Cd(II), and contact time. The adsorption of Cd(II) on HMO could be better in line with the Langmuir model, while that of Mn(II) accorded with the Freundlich model. The pseudo-second-order kinetic fitting results indicated that the removal of Cd(II) and Mn(II) on HMO belonged to chemisorption. SEM, XRD, FTIR, and XPS analysis demonstrated that Cd(II) was trapped by forming an inner-sphere complex on HMO, and the added Mn(II) and KMnO4 could regenerate MnO2 through oxidation-reduction reaction, wrapping outside of Cd(II) for a purpose of deep removal of Cd(II). HIGHLIGHTS: 1)A small amount of Mn(II) can bind to HMO without causing Cd(II) desorption 2)A large amount of Mn(II) can cause partial desorption of Cd(II) 3)Large amount of Mn(II) will partially bind to the surface of HMO or Cd(II) complexes 4)Deeply remove Cd(II) without eluting and regenerating HMO.

Targeted synthesis of a high-stability cationic porous aromatic framework for highly efficient remediation of 99TcO4−

Efficient removal of 99TcO4− from nuclear wastewater is of great significance for the safe development of nuclear energy. In this work, a viologen-based cationic porous aromatic framework (TZ-PAF) was prepared as a novel sorbent for TcO4−. With 4,4′-bipyridine as the linker units, tetraphenylmethane was selected as the knot units to construct the diamond-like topology structure of TZ-PAF, which was benefit to its outstanding structural stability (thermal stability and acid resistance). The batch sorption experiments showed that TZ-PAF possessed fast sorption kinetics, higher sorption capacity (982 mg g−1 for ReO4−) and a highest removal depth (Kd for TcO4− was 5.02 × 106 mL g−1), which could be attributed to the low-density skeleton of TZ-PAF resulting in the high density of sorption sites. XPS and SEM analyses revealed that the mechanism of TcO4−/ReO4− capture was attributed to an anion-exchanged process in which Cl− of TZ-PAF was replaced by ReO4−. And more, the excellent reusability to capture ReO4− from a highly acidic solution (64.6%) and a simulated nuclear wastewater (77.6%) were obtained. In general, this work exhibited a new sorbent for the highly efficient and deep removal of TcO4− form nuclear wastewater, and would provide a valuable insight into designing novel high-stability sorbents for wastewater treatment.

Outcomes of Hardware Removal Surgery for Children.

Hardware removal is among the most common orthopedic procedures performed in the United States. The goal of this study was to report the outcomes of deep hardware removal for children. This study received institutional review board approval. Patients younger than 18 years who underwent deep hardware removal between 2007 and 2017 were studied. We reviewed 227 procedures involving 132 boys and 95 girls. Mean follow-up was 25 months (range, 14-36 months). Mean age at the time of surgery was 12.8 years (range, 2-17 years). Mean time from initial surgery to hardware removal was 8.4 months (range, 1-72 months). Of the 227 cases, 75 used a tourniquet. Mean tourniquet time was 30.1 minutes (range, 1-118 minutes). Mean length of surgery was 44.0 minutes (range, 4-173 minutes). Mean resident level performing the surgery was postgraduate year 3 (range, postgraduate year 2 to fellow). There were 3 complications. Locations of the implanted hardware included: femur, 85; humerus, 49; tibia, 46; hip/pelvis, 17; ulna, 11; miscellaneous foot, 10; radius, 6; and fibula, 3. Indications for surgery included surgeon recommendations in 122 cases; symptomatic hardware in 68 cases, and parent wishes in 37 cases. Hardware removal for children was safe, and the outcomes were excellent. Complications of hardware removal at a teaching hospital can be minimized when a more senior resident is the primary surgeon. Despite the challenging and historically troublesome nature of deep hardware removal, the current study shows that hardware removal for children is safe and effective. [Orthopedics. 2022;45(2):e91-e95.].

Vertical-flow constructed wetland based on pyrite intensification: Mixotrophic denitrification performance and mechanism

Deep nitrogen removal from low-carbon wastewater is a pressing water treatment challenge as of yet. Eight sets of vertical-flow constructed wetland (VFCW) intensified by pyrite were designed and applied to treat with low C/N ratio wastewater in this research. The results showed that the addition of pyrite (100% added) significantly promoted TN removal with an efficiency higher than 27.05% under low C/N ratio conditions, indicating that mixotrophic denitrification was achieved in VFCW. Microbial analysis showed that the community structure and diversity of microorganisms were changed significantly, and the growth of autotrophic (Thiobacillus) and heterotrophic bacteria (Thauera) concomitantly enhanced. It is recommended that the addition amount of pyrite is 75% of the wetland volume, meantime, mixing evenly with 25% high porosity substrate (such as activated carbon, volcanic stone, etc.), which could enhance the effective adhesion of microorganisms and their contact area with pyrite, ultimately improve the denitrification capacity of the VFCW.

Interaction of impurity distribution and groove at the micro-zone of solid/liquid interface in silicon

Groove, as a special structure at the front of solid–liquid (S/L) interface, takes a great influence on the distribution of impurities for silicon. In this work, the interaction between grooves and impurities was studied, and the evolution model of groove was proposed. It has been found that the crystal growth rate and the impurity content in the groove determine the evolution behavior of the groove. Correspondingly, the migration behavior of impurities in groove with solidification was studied and the mathematical model was proposed to describe the anomalous enrichment phenomenon. This work is helpful to understand the distribution behavior of impurities in micro-zone such as groove and make a theoretical foundation for the deep removal of impurities.

Optical coherence tomography evaluation of deep dentin crack removal techniques

BackgroundThis in vitro study used optical coherence tomography for noninvasive evaluation of the effectiveness of current clinical techniques to remove deep coronal dentin cracks. MethodsStandard dentin cracks were induced on the pulpal floor of 40 decoronated, extracted, sound human posterior teeth using a diamond disk, resembling cracks extending from marginal ridges. The specimens were randomly assigned to 1 of 5 treatment groups for crack removal using airborne-particle abrasion or a bur (fissure, small round, medium round, or tapered fine diamond). Optical coherence tomographic scans were obtained before and after the crack removal. Three-dimensional image registration analyzed the amount of dentin removed and the dimensions of cracks initiated or propagated in each treatment group. ResultsParticle abrasion resulted in the smallest crack propagation in each dimension, which was significantly different from all bur groups (Mann-Whitney, P < .01). Removed dentin depth and width differed among burs (P < .05). All burs resulted in a degree of crack formation, and there was no difference in crack dimensions among bur groups (P > .05). The amount of removed dentin during crack treatment was the largest in the particle abrasion group, which was significantly different from those of the bur groups (Mann-Whitney, P < .005). ConclusionsDental burs used with the purpose of removing pulpal floor dentin cracks induced new small cracks and extended existing cracks, and the volume of removed dentin depended on the shape and size of the bur. Air particle abrasion induced the fewest new cracks despite removing larger dentin volume.

Performance analysis of a dual stage deep rain streak removal convolution neural network module with a modified deep residual dense network

Performance analysis of a dual stage deep rain streak removal convolution neural network module with a modified deep residual dense network

Deep Removal of Zinc from High Cobalt Slag and Preparation of Mnco2o4

Deep Removal of Zinc from High Cobalt Slag and Preparation of Mnco2o4

Molecular identification guided process design for deep removal of fluoride from electroplating effluent

This study developed a molecular identification method for fluoride in industrial wastewater and explored the adsorptive removal of fluoroborate by strongly basic ion exchange resin.

Removing Cloud Cover Interference from Sentinel-2 imagery in Google Earth Engine by fusing Sentinel-1 SAR data with a CNNmodel

ABSTRACT Google Earth Engine (GEE) provides a convenient platform that enables the use of a diverse array of applications based on optical satellite images covering long time periods and large areas. However, cloud contamination often causes optical satellite images to lose land surface information, which can greatly affect their spatial and temporal availability in areas with frequent cloud cover. Reconstructing the missing values is very important when researchers attempt to improve the potential for using optical satellite images. Recently, convolutional neural network (CNN)-based methods have shown great potential in cloud removal. Unfortunately, current CNN-based cloud removal methods can only be applied locally, which would result in inefficient data downloading and storage problems. To address these problems, this paper proposes a method that integrates GEE data and a multi-level feature connected CNN (DeepGEE-S2CR) to remove clouds in Sentinel-2 imagery using Sentinel-1 Synthetic Aperture Radar imagery as auxiliary data. Specifically, the training process of the multi-level feature connected CNN was conducted locally, so that cloud removal could then be performed on the client of GEE using online data with the trained CNN model. An experiment using a set of globally distributed Sentinel-2 images was conducted to validate the proposed method; the results showed the process could generate results comparable to a classic deep Sentinel-2 cloud removal method (DSen2-CR) that should be run locally (the average root mean square errors of DeepGEE-S2CR and DSen2-CR were 0.045 and 0.042, respectively). The proposed method is especially convenient for removing clouds in Sentinel-2 imagery covering a large area.

Removal of Fluorine from RECl3 in Solution by Adsorption, Ion Exchange and Precipitation

In this paper, methods of effective removal of fluorine from rare earth chloride solution by adsorption, ion exchange and precipitation with lanthanum carbonate or CO2 gas as fluorine-removal agent, respectively, were studied. The relevant parameters studied for fluorine-removal percentage were the effects of the type and dosage of fluorine-removal agent, the injection flow and mode of CO2, the initial concentration of rare earth solution and initial pH value, contact time, temperature and stirring. XRD, SEM and EDS were used to analyze and characterize the filter slag obtained after fluorine removal. SEM and EDS results showed that RECO3(OH) with a porous structure was formed in rare earth chloride solution when lanthanum carbonate was used as fluorine-removal agent, and it had strong selective adsorption for F−. The XRD spectra showed that F− was removed in the form of REFCO3 precipitates, which indicates that the adsorbed F− replaced the OH− group on the surface of RECO3(OH) by ion exchange. The experimental results showed that a fluorine-removal percentage of 99.60% could be obtained under the following conditions: lanthanum carbonate dosage, 8%; initial conc. of rare earths, 240 g/L; initial pH, 1; reaction temperature, 90 ∘C; reaction time, 2 h. Simultaneously, a fluorine-removal process by CO2 precipitation was explored. In general, RE2(CO3)3 precipitation is generated when CO2 is injected into a rare earth chloride solution. Interestingly, the results of XRD, SEM and EDS showed that the sedimentation slag was composed of REFCO3 and RE2O2CO3. It was inferred that RE2(CO3)3 obtained at the initial reaction stage had a certain adsorption effect on F− in the solution, and then F− replaced CO32− on the surface of RE2(CO3)3 by ion exchange. Therefore, F− was finally removed by the high crystallization of REFCO3 precipitation, and excess RE2(CO3)3 was aged to precipitate RE2O2CO3. The fluorine-removal percentage can reach 98.92% with CO2 precipitation under the following conditions: venturi jet; CO2 injection flow, 1000 L/h; reaction temperature, 70 ∘C; initial pH, 1; reaction time, 1.5 h; initial conc. of rare earths, 240–300 g/L; without stirring. The above two methods achieve deep removal of fluorine in mixed fluorine-bearing rare earth chloride solution by exchanging different ionic groups. The negative influence of fluorine on subsequent rare earth extraction separation is eliminated. This technology is of great practical significance for the further development of the rare earth metallurgy industry and the protection of the environment.

Anesthetic considerations in children with asthma.

Due to the high prevalence of asthma and general airway reactivity, anesthesiologists frequently encounter children with asthma or asthma-like symptoms. This review focuses on the epidemiology, the underlying pathophysiology, and perioperative management of children with airway reactivity, including controlled and uncontrolled asthma. It spans from preoperative optimization to optimized intraoperative management, airway management, and ventilation strategies. There are three leading causes for bronchospasm (1) mechanical (eg, airway manipulation), (2) non-immunological anaphylaxis (anaphylactoid reaction), and (3) immunological anaphylaxis. Children with increased airway reactivity may benefit from a premedication with beta-2 agonists, non-invasive airway management, and deep removal of airway devices. While desflurane should be avoided in pediatric anesthesia due to an increased risk of bronchospasm, other volatile agents are potent bronchodilators. Propofol is superior in blunting airway reflexes and, therefore, well suited for anesthesia induction in children with increased airway reactivity.