Recovery Ability Research Articles

Preparation and rheological properties of acrylamide-based penta-polymer for ultra-high temperature fracturing fluid

In this study, a penta-polymer PADAAN is prepared with acrylamide (AM) as the main chain material, acrylic acid (AA) as the carboxyl monomer, N-vinylpyrrolidone (NVP) as the temperature resistant monomer, N, N-dimethylacrylamide (DMAM) as the cross-linking monomer and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as the salt resistant monomer. Firstly, the best proportions of the monomers are determined, and then the rheological properties and microstructure of the polymer solution itself are studied. The 0.6 wt% PADAAN solution has a wide linear elastic region and it has good viscoelasticity and has good research value in its use as a fracturing fluid-based solution; The time required for restructuring the system structure is short and the spatial structure recovery ability is strong; The temperature resistance experiment of the fracturing fluid system (0.6 wt% PADAAN thickener base solution, 1 wt% cross-linking agent FAC-24,0.5 wt% pH regulator HAC20, 0.8 wt% FAT composited ratio deoxidizer, 0.2 wt% methanol)formulated by thickener found that the viscosity retention values of PADAAN are greater than 50mPa·s at 255 ℃, 265 ℃ and 275 ℃ respectively. In general, the new penta-polymer studied in this study can be used as a thickener for ultra-high temperature fracturing fluid with temperature resistance above 275 °C, which not only provides a reference for subsequent rheological studies of temperature-resistant polymers, but also has broad application potential in the field of hydraulic fracturing in oil and gas fields.

A signal recovery method for bridge monitoring system using TVFEMD and encoder-decoder aided LSTM

Accurate monitoring data in bridge health monitoring systems are critical for grasping the structural operation status. However, because of data missing and distortion induced by the sensor malfunction and the interference of system or measurement noise, it is hard to obtain reliable monitoring data. To settle this problem, this paper proposes a method for the recovery of bridge monitoring data based on the combination of the time varying filtering based empirical mode decomposition (TVFEMD), encoder-decoder (ED), and long short-term memory neural network (LSTM). This hybrid method can transform the problem of data recovery into a series of forecasting tasks. Specifically, TVFEMD is first used to decompose the original signal into several regular intrinsic mode functions (IMFs) with different frequency bands. Then, ED is employed to improve the interpretability and applicability of the original LSTM via constructing a sequence-to-sequence network architecture (i.e., ED-LSTM). Finally, ED-LSTM is established for each IMF to perform the desired prediction, and the final recovery result can be generated by summing each desired prediction in a linear manner. Case study based on the monitoring data in the bridge health monitoring system is used to illustrate the effectiveness of the proposed method. The results show that this method is superior to the other compared methods in terms of the data recovery ability. For example, the proposed method can realize an overall improvement of 33.90% in comparison with the original LSTM. Therefore, this method may have a potential for the recovery of bridge health monitoring data in practice.

Experimental study on the elastic-plastic dynamic response of shallow-buried corrugated steel-plain concrete composite structures under long-duration plane blast wave loading

To study the elastic-plastic dynamic response characteristics of shallow-buried corrugated steel-plain concrete (CSPC) composite structures under long-duration plane blast loads, a series of tests were conducted in a large confined blast-resistant test facility using the plane charge explosion technique (PCET), and the dynamic response and deformation laws of CSPC arches, reinforced concrete (RC) arches and plain concrete (PC) arches under different blast loads were comprehensively compared and analyzed. The test results show that under this test condition, the plane air shock wave overpressure peak with the increase in charge is basically a linear growth, but the shock wave pressure duration of action and impulse growth rate gradually decreased, the test device simulated by the explosion shock wave pressure duration of the maximum action time of more than 340 ms. Comparing the differences in the dynamic response of the three structures, it was found that when the peak long-duration shock wave overpressure acting on the structure reached 0.09 MPa, the PC model had plastic deformation, and the combined reinforced concrete and CSPC structure exhibited fully elastic deformation. When the peak shock wave overpressure reaches 0.238 MPa, the RC model begins to show plastic deformation. When the peak shock wave overpressure increased to 0.315 MPa, all models produced significant plastic deformation. The deformation resilience of the CSPC composite structure under the above-mentioned blast shock wave load is greater than that of RC and PC structures, which have good deformation recovery ability and can effectively reduce the damage to the structure by blast shock. On the contrary, the peak structural vibration acceleration caused by the blast shock wave is greater in the CSPC combined structure than in the RC and PC structure, and the deformation rebound and oscillation of the corrugated steel plate is the main way of impact energy dissipation. The results of the study provide an experimental basis for the simulation of long-duration plane blast waves and the optimal design of CSPC blast-resistant structures.

Structure and properties of citric acid cross-linked chitosan/poly(vinyl alcohol) composite films for food packaging applications

In this study, the composite films of poly(vinyl alcohol) and citric acid cross-linked chitosan were prepared, and the effect of mass ratio on their structure and properties was investigated in detail. Chitosan was cross-linked by citric acid via an amidation reaction at an elevated temperature, which was confirmed by infrared spectra and X-ray photoelectron spectra. Chitosan is miscible with PVA due to the formation of strong hydrogen bonds between them. Among these composite films, 1:1 CS/PVA film showed excellent mechanical properties, good creep resistance, and shape recovery ability, attributing to its high crosslinking degree. In addition, this film possessed hydrophobicity, excellent self-adhesion property, and the lowest WVP, and it was successfully used as a packaging material for cherry. These observations indicate that the cooperative effects of crosslinking and hydrogen bonds control the structure and properties of chitosan/PVA composite film, which is a very potential material for food packaging and preservation.

Novel Co3O4@TiO2@CdS@Au double-shelled nanocage for high-efficient photocatalysis removal of U(VI): Roles of spatial charges separation and photothermal effect

Effective spatial separation and utilization of photogenerated charges are critical for photocatalysis process. Herein, novel Co3O4 @TiO2 @CdS@Au double-shelled nanocage (CTCA) with spatially separated redox centers was synthesized by loading Co3O4 and Au NP cocatalysts on the inner and outer surfaces of Z-scheme heterojunction (TiO2 @CdS). The reduction rate constant of U(VI) by CTCA reached 0.218 min−1 under simulated sunlight irradiation, which was 6.6, 3.2 and 36.3 times than that of monolayer CTCA (0.033 min−1), CTC (0.068 min−1) and CT (0.006 min−1). The full-spectrum light-assisted photothermal catalytic performance can enable CTCA to remove 98.8% of U(VI) and degrade nearly 90% of five organic pollutants simultaneously. Detailed characterizations and theory calculations revealed that the photogenerated holes and electrons in CTCA flow inward and outward. More importantly, Co3O4 acts as a “nano heater” to generate the photothermal effect for further enhancing the charge transfer and accelerating the surface reaction kinetics. Meanwhile, the photogenerated electrons and superoxide radicals play a dominant role in reducing the adsorbed U(VI) to insoluble (UO2)O2·2H2O(s). This work provides valuable input toward a novel double-shelled hollow nanocage reactor with excellent photothermal catalysis ability for efficient recovery U(VI) from uranium mine wastewater to address environmental contamination issues.

Anti-Penetration Performance of Composite Structures with Metal-Packaged Ceramic Interlayer and UHMWPE Laminate

The impact response of a composite structure consisting of a metal-packaged ceramic interlayer and an ultra-high molecular weight polyethylene (UHMWPE) laminate has been studied through a ballistic test and numerical simulation. The studied structure exhibits 50% higher anti-penetration performance than the traditional ceramic/metal structure with the same areal density. The metal-packaged ceramic interlayer and the UHMWPE laminate are key components in resisting the penetration. By using a metal frame to impose three-dimensional constraints on ceramic tiles, the metal-packaged ceramic interlayer can limit the crushing of the ceramic and contain the broken ceramic fragment to improve the erosion of the projectile. The large deformation of UHMWPE laminate absorbs a large amount of energy from the projectile. By decreasing the amplitude of the shock wave and changing the distribution of the impact load in the structure, the projectile has longer residence time on the interlayer. The anti-penetration performance shows within 10% variation when the impact position is varied. Due to the asymmetric deformation and high elastic recovery ability of the UHMWPE laminate, the projectile trajectory deflection is increased, and the broken ceramic fragments are restrained, thereby mitigating after-effect damage caused by the projectile after penetrating the structure.

Evaluation of Apical and Molecular Effects of Algae Pseudokirchneriella subcapitata to Cerium Oxide Nanoparticles.

Cerium oxide engineered nanoparticles (nCeO2) are widely used in various applications and are, also, increasingly being detected in different environmental matrixes. However, their impacts on the aquatic environment remain poorly quantified. Hence, there is a need to investigate their effects on non-target aquatic organisms. Here, we evaluated the cytotoxic and genotoxic effects of <25 nm uncoated-nCeO2 on algae Pseudokirchneriella subcapitata. Apical (growth and chlorophyll a (Chl a) content) and genotoxic effects were investigated at 62.5-1000 µg/L after 72 and 168 h. Results demonstrated that nCeO2 induced significant growth inhibition after 72 h and promotion post 96-168 h. Conversely, nCeO2 induced enhanced Chl a content post 72 h, but no significant changes were observed between nCeO2-exposed and control samples after 168 h. Hence, the results indicate P. subcapitata photosynthetic system recovery ability to nCeO2 effects under chronic-exposure conditions. RAPD-PCR profiles showed the appearance and/or disappearance of normal bands relative to controls; indicative of DNA damage and/or DNA mutation. Unlike cell recovery observed post 96 h, DNA damage persisted over 168 h. Thus, sub-lethal nCeO2-induced toxicological effects may pose a more serious threat to algae than at present anticipated.

Transcriptome profiling reveals characteristics of hairy root and the role of AhGLK1 in response to drought stress and post-drought recovery in peanut

BackgroundHR (hairy root) has emerged as a valuable tissue for the rapid characterization of plant gene function and enzyme activity in vivo. AhGLK1 (Arachis hypogaea L. golden2-like 1) is known to play a role in post-drought recovery. However, it is unclear (a) whether HR has properties that are distinct from those of PR (primary root); and (b) which gene networks are regulated by AhGLK1 in response to drought stress and recovery in peanut.ResultsWe found that cells of the root tip cortex were larger in HR than in PR, while a total of 850 differentially expressed genes (DEGs) were identified in HR compared to PR. Eighty-eight of these DEGs, relating to chlorophyll and photosynthesis, were upregulated in HR. In addition, AhGLK1-OX (AhGLK1-overexpressing) HR showed a green phenotype, and had a higher relative water content than 35 S::eGFP (control) HR during drought stress. RNA-seq analysis showed that 74 DEGs involved both in the drought response and the post-drought recovery process were significantly enriched in the galactose metabolism pathway. GO terms enrichment analysis revealed that 59.19%, 29.79% and 17.02% of the DEGs mapped to the ‘biological process’ (BP), ‘molecular function’ (MF) and ‘cellular component’ (CC) domains, respectively. Furthermore, 20 DEGs involved in post-drought recovery were uniquely expressed in AhGLK1-OX HR and were significantly enriched in the porphyrin metabolism pathway. GO analysis showed that 42.42%, 30.30% and 27.28% of DEGs could be assigned to the BP, MF and CC domains, respectively. Transcription factors including bHLH and MYB family members may play a key role during drought stress and recovery.ConclusionOur data reveal that HR has some of the characteristics of leaves, indicating that HR is suitable for studying genes that are mainly expressed in leaves. The RNA-seq results are consistent with previous studies that show chlorophyll synthesis and photosynthesis to be critical for the role of AhGLK1 in improving post-drought recovery growth in peanut. These findings provide in-depth insights that will be of great utility for the exploration of candidate gene functions in relation to drought tolerance and/or post-drought recovery ability in peanut.

Thermal performance of the aquifer thermal energy storage system considering vertical heat losses through aquitards

The aquifer thermal energy storage (ATES) system is an efficient method to overcome the gap between energy supply and demand over time and space. Heat storage and preservation abilities are key issues of a successful ATES project. However, most of previous studies only focus on heat storage and recovery abilities of the ATES, while the heat preservation ability of aquitards is neglected. Besides, effects of key factors on heat losses into aquitards still remain unclear, which makes appropriately selecting reservoirs for the heat storage challenging. Thus, the heat loss efficiency is defined to represent the heat preservation ability of aquitards, through which ATES thermal performances are comprehensively evaluated. Effects of key factors on thermal performances are analyzed and optimal reservoirs for the heat storage are recommended. Results indicated that key factors had different impacts on heat losses and thermal recovery. The conduction was the major loss mode and was sensitively affected by aquitard parameters. An aquifer with a lower thermal conductivity, a higher porosity and a superior heat capacity was more suitable for the heat storage. The aquitard with lower porosity, thermal conductivity and heat capacity was better. On the premise of sealing, increasing the aquitard permeability was conducive.

Multifunctional nano-cellulose aerogel for efficient oil–water separation: Vital roles of magnetic exfoliated bentonite and polyethyleneimine

Discharge of oily wastewater have caused serious environmental pollution and resources waste. Due to the characteristics of hydrophobic and porous, aerogel has been proved to be a kind of promising oil-adsorbing materials for oil adsorption and recovery. However, dissatisfactory adsorption properties and recovery ability of aerogel for oil pollution treatment were still critical issues hindering aerogel applications. Magnetic exfoliated bentonite (MBTex) possesses good magnetic separation property, anti-mold ability and anti-extruding strength. Meanwhile, Polyethyleneimine (PEI) can cross-link with nano-cellulose to form sponge-like structure and prevent the corrosion of magnetic media. Basing on the above-mentioned characteristics of MB and PEI, a new carboxy cellulose nanofibers/polyethyleneimine/magnetic exfoliated bentonite (CNF-C/PEI/MBTex) aerogel was synthesized using simple hydrothermal and chemical vapor deposition (CVD) methods, and the adsorption and recovery ability of different oil on samples were investigated. The results showed that CNF-C/PEI/MBTex aerogel exhibited superhydrophobic properties (contact angle 151°), excellent mechanical properties (full recovery at 80% pressure), anti-mold properties (the anti-mold efficiency was more than 90%) and magnetic responsivity. Furthermore, CNF-C/PEI/MBTex aerogel exhibited high oil adsorption capacity (24.6 ∼ 77.8 times higher than its original weight) and can recover the adsorbed oil by simple hand squeezing (the adsorption capacity still exceeds 90% after 20 cycles). In summary, the present work provides a valuable reference for the synthesis of high-performance adsorbent materials for oil–water separation using cost-effective clays combined with polymers.

Application of mesoporous CaO@g-C3N4 nanosorbent materials for high-efficiency removal of Pb (II) from aqueous solution

Removing heavy metals from aqueous solutions is an environmental challenge of rising concern. Discovering new materials based on nanostructures with enhanced adsorption towards heavy metals can be experimentally difficult and expensive. As an alternative strategy, designing efficient nanostructures acting as adsorbents through computational studies is a viable solution in the adsorption research area. In the current study, density functional theory (DFT) calculations were performed prior to experimental investigation to predict the potential use of CaO@g-C3N4 nanostructure as an adsorbent for lead ions. The analysis of the interaction energies pointed out the effect of incorporating CaO into the g-C3N4 framework to improve the adsorption properties. The eco-friendly CaO/g-C3N4 composite was experimentally tested as an absorbent medium for the removal of lead ions in aqueous solution. The results show that lead (II) ions adsorption onto CaO@g-C3N4 equilibrated in 4 min, with an adsorption percent and quantity of 99.88% and 525.5 mg/g, respectively, at pH 3. Additionally, CaO@g-C3N4 nanostructures may be easily recovered from the solution for reuse after five successive cycles. The mathematical models Langmuir and PSO were shown to be the most appropriate for modeling the adsorption data in equilibrium and nonequilibrium states, respectively. The CaO@g-C3N4 nanostructures, therefore, can be used as a suitable adsorbent for aqueous lead (II) ions due to their ease of manufacture, high adsorption efficacy, recovery ability, and reusability.

Electrochemical detection of miRNA‐21 based on molecular beacon formed by thymine‐mercury(II)‐thymine base pairing

AbstractWe present a molecular beacon‐based electrochemical biosensor with high sensitivity and specificity for the detection of microRNA‐21. A special oligonucleotide probe was prepared containing a nucleotide sequence complementary to miR‐21 and consecutively linking eight and six thymines to the 3′ and 5′ ends, respectively, to allow the formation of a T‐Hg2+‐T complex‐based molecular beacon on the electrode surface by the selective binding of Hg2+ ions. The introduction of multiple thymines at the end of the probe avoids base overlapping between the miRNA sequence and the molecular beacon formation sequence, enabling a universal probe design that can detect all types of miRNAs. A ferrocene moiety was attached to the 5′‐end of the specially designed probe as an electrochemical signal indicator. The molecular beacons are formed by six consecutive T‐Hg2+‐T pairs by Hg2+ addition, and the molecular beacons are destroyed by perfect hybridization between 22 bases as a result of miR‐21 addition. Based on this detection mechanism, we were able to detect miR‐21 with LODs of 0.64 pM and 1.08 pM in buffer solution and human serum, respectively. In addition, the specifically designed oligonucleotide probe showed perfect specificity in detecting only miR‐21 without binding to other miRNAs. Finally, the sensor showed excellent miR‐21 recovery ability from samples spiked into serum, indicating that the method described in this study worked perfectly, even in a turbid complex matrix such as human serum.

Application of bio-resin in road materials: Rheological and chemical properties of asphalt binder modified by lignin-phenolic resin

The development of new sustainable green road materials with bio-resin is a hot topic in pavement engineering. To improve the efficiency of lignin as a sustainable pavement material, an asphalt binder modified by lignin-based resin was prepared, and its properties were evaluated. Firstly, lignin was extracted from biomass (corn straw) by thermochemical method to prepare lignin-based phenol formaldehyde (LPF) resin. After that, LPF resin-modified asphalt and phenol formaldehyde (PF) resin-modified asphalt were prepared. Then the effects of LPF resin and PF resin on asphalt properties were evaluated by chemical analysis and rheological performance tests. The results showed that lignin was involved in resin synthesis, LPF resin with PF resin had similar thermogravimetric curves, and the thermal stability of LPF resin was slightly lower than PF resin. Both LPF resin and PF resin can increase the proportion of large-size molecules and elastic components of asphalt binder and enhance its high-temperature deformation recovery ability. Moreover, the fatigue performance and aging resistance of the binder were also enhanced by the addition of LPF resin and PF resin. Although the addition of LPF resin and PF resin will increase the G-R parameters of virgin asphalt binder, it can reduce the effect of aging on the G-R parameters of asphalt binder. It seems that LPF resin and PF resin can improve the cracking resistance of asphalt binders.

Stability Control of Quadruped Robot Based on Active State Adjustment.

The quadruped robot has a strong motion performance and broad application prospects in practical applications. However, during the movement of the quadruped robot, it is easy to be affected by external disturbance and environmental changes, which makes it unable to achieve the ideal effect movement. Therefore, it is very important for the quadruped robot to adjust actively according to its own state detection. This paper proposes an active state adjustment control method based on its own state, which can realize disturbance recovery and active environment adaptation. Firstly, the controller is designed according to the physical model of the quadruped robot, and the foot forces are optimized using the quadratic program (QP) method. Then, the disturbance compensation method based on dynamic analysis is studied and combined with the controller itself. At the same time, according to the law of biological movement, the movement process of the quadruped robot is actively adjusted according to the different movement environment, so that it can adapt to various complex environments. Finally, it is verified in a simulation environment and quadruped robot prototype. The results show that the quadruped robot has a strong active disturbance recovery ability and active environment adaptability.

A bilevel task allocation method for heterogeneous multi-UUV recovery system

This paper presents a novel task allocation method for multiple unmanned underwater vehicles (multi-UUV) recovery systems. Specifically, a bilevel model that enjoys the advantages of centralized and distributed methods is constructed for mothership and cooperative constraints. In the centralized upper-level, an improved Gaussian mixture mode (IGMM) is presented, and an improved discrete crow search algorithm (IDCSA) is proposed. Thus, the leaders are clustered into subgroups, and the matching relationship between motherships and subgroups is established. In the distributed lower-level, the proposed consensus-based bundle algorithm with group constraint (CBBA-GC) addresses the allocation problem between subgroups and heterogeneous follower UUVs. It is found that the proposed bilevel method can achieve conflict-free and load-balanced multi-UUV recovery task allocation when the communication capability of each UUV and motherships recovery ability are heterogeneous.

A Self-Healable and Recyclable Zwitterionic Polyurethane Based on Dynamic Ionic Interactions.

Polyurethanes with self-healing and reprocessing capabilities are promising in eco-friendly applications. Here, a self-healable and recyclable zwitterionic polyurethane (ZPU) was developed by introducing ionic bonds between protonated ammonium groups and sulfonic acid moieties. The structure of the synthesized ZPU was characterized by FTIR and XPS. The thermal, mechanical, self-healing and recyclable properties of ZPU were also investigated in detail. Compared with cationic polyurethane (CPU), ZPU shows similar thermal stability. The physical cross-linking network formed between zwitterion groups can dissipate strain energy as a weak dynamic bond, endowing ZPU with outstanding mechanical and elastic recovery properties, including the high tensile strength of 7.38 MPa, high elongation at a break of 980%, and fast elastic recovery ability. Additionally, ZPU exhibits a healing efficiency of over 93% at 50 °C for 1.5 h as a result of the dynamic reconstruction of reversible ionic bonds. Furthermore, ZPU can be well reprocessed by solution casting and hot-pressing with a recovery efficiency above 88%. The excellent mechanical properties, fast repairing capability, and good recyclability not only enable polyurethane with a promising application in protective coatings for textiles and paints but also make it a superior candidate as stretchable substrates for wearable electronic devices and strain sensors.

The influence of pregelatinized starch on the rheology of a gellan gum-collagen IPN hydrogel for 3D bioprinting

Hydrogel scaffolds infused with stem cells are valuable alternatives to skin grafts in replacement of lost host tissues. In a prior study, we developed an adipose-derived stem cells (ADSC)-laden gellan gum-collagen interpenetrating network (IPN) hydrogel with enhanced wound healing properties upon application on murine full thickness burn wounds. With the perspective of enabling the clinical translation and healthcare adaptation of the hydrogel wound-dressing, we report a novel ADCS-laden collagen-gellan gum full IPN hydrogel formula compatible with 3D bioprinting technology. The stable new bio-ink showed improved printability for extrusion-based 3D biofabrication and preserved scaffold quality for stem cell proliferation. Pregelatinized starch (PGF, PREGEFLO®PI10) and glycerol were successfully incorporated to the bio-ink as molecular lubricant and hydrophilic plasticizer. When subjected to rheological measurements, the new glycerol-PGF-gellan gum composite hydrogel demonstrated good shear recovery ability, improved resistance to step-strain deformations and adequate stiffness as cell-conducive environment. Subsequently, a dual-head two-step temperature-guided 3D bioprinting methodology was developed to extrude ADSC-laden collagen into the composite hydrogel thick film to achieve in-situ polymer interpenetration. After their fabrication, the printed cell-laden hydrogel constructs were able to maintain high shape fidelity and stability after 21 days of incubation in cell culture media. Results from cell proliferation assay (MTS) and confocal laser scanning microscopy (CLSM) suggested that ADSC retained their normal cellular functions of adhesion, proliferation, and migration within the 3D bioprinted hydrogel scaffold. Taken together, our study brings forward the use of PREGEFLO®PI10 in upgrading the ADSC-laden IPN hydrogel formula towards potential clinical translation of synthetic skin grafts.

Self-Disciplined Nonsmooth Coordination Control for Battery Energy Storage System in Autonomous DC Microgrids Toward Large-Signal Stability

For a Battery Energy Storage System (BESS)-based autonomous DC microgrid, owing to the coupling complexity between multiple control objectives under a hierarchical control framework, coordination control for large-signal stabilization is well-acknowledged as a non-trivial problem. This paper aims to present a self-disciplined nonsmooth coordination control strategy to address the multi-objective task within one framework. Firstly, a nonsmooth composite regulation law is designed to mitigate the increasing constant power loads (CPLs) by employing a feedforward compensation. Secondly, a dynamic droop strategy aiming for dynamic power allocation for state-of-charging (SOC) balancing of BESS is built based on a nonsmooth dynamic average consensus protocol with low communication cost. Then by utilizing a dynamic power allocation strategy and a large-signal stabilizer for each energy storage unit (ESU), both SOC dynamic balancing and system level large-signal stability can be ensured. Moreover, a fast performance recovery ability can be promised by bringing into two convergence rate coordination factors. Simulation and comparative experimental studies have demonstrated the efficacy of the proposed control strategy.

Busbar Voltage Control of DC Microgrid Group Based on Whale Optimization Algorithm and Fuzzy Control

Aiming at the problems of system response lag, poor anti-interference ability, and poor recovery ability of fuzzy dual closed-loop control, this paper proposes a fuzzy dual closed-loop control based on a whale optimization algorithm to optimize the control effect by simulating the foam attack mechanism of humpback whales, solving mathematical and structural optimization problems, adjusting quantization factor and scaling factor, and adjusting PI parameters in real-time. Matlab/Simulink is used to create the model. The experimental results show that the system has a quicker reaction, smaller overshoot, greater anti-interference capability, and improved robustness in various situations under the new control strategy.

Dual crosslinked poly(acrylamide-co-N-vinylpyrrolidone) microspheres with re-crosslinking ability for fossil energy recovery

Microspheres have been proposed to be applied in controlling wastewater production for mature oilfields and migrating leakage for gas and nuclear waste storage. However, it remains challenging for stacked microspheres to maintain strong blocking ability in micron-sized small pores or fractures. In this study, a novel microsphere was developed with comprehensive properties including high deformability and long re-crosslinking time upon tunable swelling ratio for the applications. A dual covalent and physical crosslinking strategy was used to develop novel microspheres reinforced by a hydrogen bond (H-bond, between pyrrole ring and amide group) and coordination bond (between chromium acetate (CrAc) and carboxyl group via hydrolysis process). The microspheres were fabricated via radical suspension copolymerization of acrylamide (AM) and N-vinylpyrrolidone (NVP) in the presence of N, Nʹ-methylene-diacrylamide (MBA) with subsequent introduction of CrAc. MBA induced the strong crosslinking through a chemical covalent bond and H-bond triggered the weak crosslinking which was anticipated to prohibit the hydrolysis of the amide group. The H-bond delayed the formation of CrAc coordination bond by delaying the formation of carboxyl groups, resulting in achieving the re-crosslinking of the microspheres. As a result, the microspheres exhibit the tunable initial size (8–165 μm) and swelling ratio (30–630 μm), with controllable network parameters. The microspheres showed high migration ability (can transport through pores with 1/16 size of microsphere itself), and long re-crosslinking time (up to 16.5 days). The re-crosslinked gel demonstrated dual network structure with districted mesh size ζ distribution.