Double-layer System Research Articles

Long-range hydrophobic force enhanced interfacial photocatalysis for the submerged surface anti-biofouling.

Developing anti-biofouling and anti-biofilm techniques is of great importance for protecting water-contact surfaces. In this study, we developed a novel double-layer system consisting of a bottom immobilized TiO2 nanoflower arrays (TNFs) unit and an upper superhydrophobic (SHB) coating along with the assistance of nanobubbles (NBs), which can significantly elevate the interfacial oxygen level by establishing the long-range hydrophobic force between NBs and SHB and effectively maximize the photocatalytic reaction brought by the bottom TNFs. The developed NBs-SHB/TNFs system demonstrated the highest bulk chemical oxygen demand (COD) reduction efficiency at approximately 80% and achieved significant E. coli and Chlorella sp. inhibition efficiencies of 5.38 and 1.99 logs. Meanwhile, the system showed a sevenfold higher resistance to biofilm formation when testing in a wastewater matrix using a wildly collected biofilm seeding solution. These findings provide insights for implementing nanobubble-integrated techniques for submerged surface protection.

Coulomb Drag and Heat Transfer in Strange Metals.

We address Coulomb drag and near-field heat transfer in a double-layer system of incoherent metals. Each layer is modeled by an array of tunnel-coupled SYK dots with random interlayer interactions. Depending on the strength of intradot interactions and interdot tunneling, this model captures the crossover from the Fermi liquid to a strange metal phase. The absence of quasiparticles in the strange metal leads to temperature-independent drag resistivity, which is in strong contrast with the quadratic temperature dependence in the Fermi liquid regime. We show that all the parameters can be independently measured in near-field heat transfer experiments, performed in Fermi liquid and strange metal regimes.

Analytical solutions for contaminant transport through a GMB/CCL composite liner system considering effective porosity and thermodiffusion

This study presents analytical solutions for one-dimensional contaminant transport through a saturated double-layer composite liner system consisting of a geomembrane (GMB) and a compacted clay liner (CCL), considering the effects of CCL effective porosity, GMB defects, and thermodiffusion. The solutions provide temperature distribution at steady state and contaminant concentration distribution and total contaminant mass flux for transient-state condition. The heat transfer algorithm of the solutions accounts for advection, conduction, and thermal mechanical dispersion, while the solute transport algorithm of the solutions accounts for molecular diffusion, advection, mechanical dispersion, sorption, and thermodiffusion. The proposed solutions are validated against experimental data and verified against numerical solution. Using the proposed solutions, a series of parametric studies is conducted and the results indicate that neglecting the effect of thermodiffusion can underestimate the contaminant outflow rate at the bottom of the GMB/CCL liner by 6.9%∼130%. Depending on conditions, the effect of thermodiffusion on contaminant transport through the GMB/CCL liner decreases with increasing leachate head, increasing length of GMB wrinkle, and increasing number of GMB defects. CCL effective porosity also has a significant impact on contaminant transport through the GMB/CCL liner system, and neglecting this effect can substantially overestimate the contaminant outflow rate.

Intrinsic Properties of Composite Double Layer Grid Superstructures

This paper examined the opportunities of composite double-layer grid superstructures in short-to-medium span bridge decks. It was empirically shown here that a double-layer grid deck system in composite action with a thin layer of two−way reinforced concrete slab introduced several structural advantages over the conventional composite plate-girder superstructure system. These advantages included improved seismic performance, increased structural rigidity, reduced deck vibration, increased failure capacity, and so on. Optimally proportioned space grid superstructures were found to be less prone to progressive collapse, increasing structural reliability and resilience, while reducing the risk of sudden failure. Through a set of dynamic time-series experiments, considerable enhancement in load transfer efficiency in the transverse direction under dynamic truck loading was gained. Furthermore, the multi-objective generative optimization of the proposed spatial grid bridge (with integral variable depth) using evolutionary optimization methods was examined. Finally, comprehensive discussions were given on: (i) mechanical properties, such as fatigue behavior, corrosion, durability, and behavior in cold environments; (ii) health monitoring aspects, such as ease of inspection, maintenance, and access for the installation of remote monitoring devices; (iii) sustainability considerations, such as reduction of embodied Carbon and energy due to reduced material waste, along with ease of demolition, deconstruction and reuse after lifecycle design; and (iv) lean management aspects, such as support for industrialized construction and mass customization. It was concluded that the proposed spatial grid system shows promise for building essential and sustainable infrastructures of the future.

An interfacial solar evaporation enabled autonomous double-layered vertical floating solar sea farm

Water, energy, and food security are the three most critical elements for achieving the 2030 United Nations' Sustainable Development Goals. While much effort has been focused on the development of interfacial solar evaporation technology for seawater desalination, limited effort has been directed towards potential sustainable agricultural applications. This work addresses this gap by developing a self-sustaining and solar-driven offshore double-layered sea farm system to address growing global shortages in clean water, agricultural land resources and food supply. During a long-term field test, this unique design was used to successfully germinate and grow, with a survival rate of 80%, three common vegetable crops (broccoli, lettuce, and Pak Choi) on seawater surfaces without maintenance nor additional clean water irrigation. Thus, this design could potentially make a significant contribution to sustainable agriculture production in the seawater-energy-food nexus.

Comprehensive evaluation and prediction of interlayer bonding characteristics of double-layered asphalt systems under various factors

This study aims to evaluate the interlayer bonding characteristics between double-layered asphalt systems. Three typical asphalt structures were chosen for evaluation. In each case, the bottom layer comprised of a dense graded asphalt concrete (AC-20) while three different asphalt mixtures were applied in surface layer: a dense graded mixture (AC-13), stone mastic asphalt (SMA-13), and open-graded friction course (OGFC-13). The effects of interface morphology, loading, and temperature conditions on interlayer bonding properties were considered. The interlayer shear and tensile strengths of the asphalt systems were tested using ‘shear-compression’ and ‘shear-tensile’ loading mode set ups, and the relationship between interface morphology and interlayer bond strength was quantitatively analyzed using 3D laser scanning. In addition, statistical analysis was performed to determine the significance level of each factor, followed by developing and validating prediction models for interlayer bond strength using multivariate nonlinear regression. The results showed that all factors had a significant effect on interlayer bonding performance, with temperature being the most prominent contributing factor. Increasing normal pressure had a positive effect on preventing the attenuation of interlayer shear strength, while an increase in shear stress was found to intensify the degradation of interlayer tensile strength. Moreover, interlocking and ensuring sufficient contact at the layer interface were demonstrated to enhance the interlayer friction effect positively. However, high normal stress could potentially lead to damage at the interface. Finally, the developed prediction models exhibited a high level of accuracy in estimating interlayer bond strengths and were able to explain over 97% and 98% of measured interlayer shear and tensile strengths, respectively. Employing a properly graded surface layer can improve the frictional and contact effects at the layer interface, thereby enhancing the overall interlayer bonding performance.

Optimal bi-planar gradient coil configurations for diamond nitrogen-vacancy based diffusion-weighted NMR experiments

IntroductionDiffusion weighting in optically detected magnetic resonance experiments involving diamond nitrogen-vacancy (NV) centers can provide valuable microstructural information. Bi-planar gradient coils employed for diffusion weighting afford excellent spatial access, essential for integrating the NV-NMR components. Nevertheless, owing to the polar tilt of roughly 55^{circ } of the diamond NV center, the primary magnetic field direction must be taken into account accordingly.MethodsTo determine the most effective bi-planar gradient coil configurations, we conducted an investigation into the impact of various factors, including the square side length, surface separation, and surface orientation. This was accomplished by generating over 500 bi-planar surface configurations using automated methods.ResultsWe successfully generated and evaluated coil layouts in terms of sensitivity and field accuracy. Interestingly, inclined bi-planar orientations close to the NV–NMR setup’s requirement, showed higher sensitivity for the transverse gradient channels than horizontal or vertical orientations. We fabricated a suitable solution as a three-channel bi-planar double-layered PCB system and experimentally validated the sensitivities at 28.7 mathrm mT/m/A and 26.8 mathrm mT/m/A for the transverse G_{x} and G_{y} gradients, and 26 mathrm mT/m/A for the G_{z} gradient.DiscussionWe found that the chosen relative bi-planar tilt of 35^{circ } represents a reasonable compromise in terms of overall performance and allows for easier coil implementation with a straight, horizontal alignment within the overall experimental setup.

Establishing a transient model of double-layer porous media interfacial evaporation system to reveal the relationship between porous media parameters and evaporation performance

The solar interfacial evaporation system can generate steam efficiently by localizing solar thermal energy to heat air–water interface, which has great application potential in seawater desalination, sewage treatment, and other fields. At present, the solar absorption layer and substrate of the interfacial evaporation system are mainly made of carbon materials, sponges, foams, and other porous media materials. However, the transient interfacial evaporation heat and mass transfer model and the influence of the physical parameters of porous media on evaporation performance have rarely been investigated. Based on heat and mass transfer theory of porous media, a transient theoretical model of porous media interfacial evaporation system is established in this paper. Moreover, the effects of physical parameters such as the porosity and thermal conductivity of porous media on evaporation performance are analyzed, and the accuracy of the model is verified through outdoor experiments. Based on the model calculation, as the porosity of the substrate increases, the evaporation rate and efficiency of the evaporator first increase and then decrease. The lower the thermal conductivity of the substrate and the higher the porosity and thermal conductivity of the solar absorption layer are, the better the evaporation performance is, but the growth rate gradually decreases. Therefore, the relationship between the improvement of evaporation performance and the increased cost caused by the improvement of material properties needs to be considered. The model and related theoretical analysis results can provide a theoretical basis for system structure optimization, material selection and other aspects of future research on double-layer porous media interfacial evaporation system.

The Ground Test System of Double Layer Air Floating Platform and Its Application

The suspension test system within the high microgravity scientific experiment cabinet is equipped with double-layer vibration isolation, effectively isolating external disturbances and creating a high microgravity environment within the inner body. Based on this characteristic, this paper proposes a double-layer plane air platform ground test system design. By using a high-precision acceleration sensor and gyroscope of the suspension test platform, the system coordinates the measurement of the double-layer air floating platform. The control mode and algorithm for double-layer vibration isolation in the suspension test platform are simulated through ground physics. Ground verification results from the double-layer plane air flotation test system show that the double-layer attitude control hardware of the suspension test platform meets the requirements, and the algorithm control effect is good, which provides sufficient experimental evidence for the normal operation of the suspension test system in orbit.

Energy performance based optimization of building envelope containing PCM combined with insulation considering various configurations

Phase change material (PCM) is considered as a promising solution for reducing heating and cooling energy consumption by integrating them into the building envelope, which in turn reduces CO2 emissions. In this paper numerical simulations were carried out to evaluate the energy performance based optimization of envelope building integrated PCM. The effect of several parameters (PCM melting temperature, PCM layer combined with insulation, PCM layer and insulation layer thickness, double PCM layer system in the double external wall, and air layer interaction with PCM in roof) on energy savings in two typical models of residential buildings in Tunisia are investigated. Results show that energy demand reduction of 73.81% and 76.46% can be achieved under the optimal conditions of application of the PCM integrated in simple wall and double wall buildings respectively. This is associated with significant reduction of CO2 emission. Moreover, PCM layer performance is improved by increasing its thickness with an optimal value of 6 cm. Two PCM layers located in the middle of the double wall involve higher energy saving than a simple PCM layer.

Geomembrane leaks detection and leakage correlation factor analysis of composite liner systems for fifty-five (55) solid waste landfills in China

In composite liner system (CLS), there are little field data on the number, size, and shape of geomembrane (GMB) holes, which are the key parameters to identify and evaluate the volume of leachate leakage from landfills. In this paper, in-situ detection of GMB holes in composite liner systems of 55 solid waste landfills in China was conducted by electrical leak location (ELL) method, and the following conclusions were drawn. The holes frequency, equivalent radius, and theoretical leakage volume of double-layer systems are lower than those of single-layer systems under the same geotextile (GT) density by 28.2%, 51.4%, and more than 60%, respectively. As the thickness of GMB increases, the holes frequency, equivalent radius and theoretical leakage volume reduce observably. Regarding protecting GMB, the density of geotextiles should not be less than 600 g/m2. Through the analysis of various correlation factors, the thickness of geomembrane is an important parameter affecting the amount of leakage. This study will provide a reference for analyzing the data of field investigation, which would provide constructive suggestions for the composite liner system.

Simulation and performance analysis of passenger bus collision with rigid guardrail of expressway bridge

Aiming at the anti-collision performance of SS-grade concrete guardrail of Chinese highway bridges, the nonlinear dynamic simulation of collision is carried out. On this basis, aiming at the defects of rigid guardrail, a rigid and flexible composite double-layer guardrail is proposed, and its anti-collision performance is evaluated. The vehicle factor analysis shows that the energy absorbed by the guardrail system, crash force, guardrail damage and reinforcement stress range increase with the increase of vehicle speed and impact angle. The effect of concrete grade on improving the anti-collision performance of guardrails is limited. It is not that the higher the strength grade, the better the effect. Compared with concrete guardrail, the vehicle deformation energy of double-layer guardrail system is only 59.1% of that of concrete guardrail system. This shows that the deformation of the vehicle is more serious when the vehicle hits the concrete guardrail, and the damage to the driver and passenger is greater, while the double-layer guardrail can improve the safety of the driver and passenger. The crash force of double-layer guardrail is reduced, so the impact suffered by passengers is reduced and the double-layer guardrail has good buffering effect.

Improving blast protection of double-layered system for infilled masonry wall in frame structure

To dissipate a large amount of blast energy as well as realize a reasonable load transfer to the beam and column instead of the vulnerable wall in the frame structure, this study employs a novel double-layered system to protect the infilled vulnerable masonry wall to resist blast loads. The system comprises a sacrificial cladding directly exposed to the blast to dissipate energy and connectors to facilitate load transfer and mitigation. Based on the quasi-static compressive test on the connector, the field blast test on the sacrificial cladding and frame structure with an infilled masonry wall, their respective numerical models are established and validated with ANSYS/LS-DYNA, which facilitates the model establishment of the frame structure protected by the double-layered system subjected to blast load. The numerical results indicate that the system effectively mitigates the damage to the masonry wall and reduces the load transferred to the frame compared to that without protection. However, large bending deformation of the sacrificial cladding may still result in collision damage to the vulnerable wall which makes it difficult to be applied in engineering practice. To improve the protective performance of the double-layered system and reduce the possibility of the occurrence of a collision between the sacrificial cladding and the wall, several measures, including connector layout optimization, rear plate strengthening with stiffeners, and appropriate connector height determination have been proposed. The numerical results demonstrate that installing connectors at four edges, adding 5 × 5 stiffeners on the rear surface of the sacrificial cladding, and appropriately designing the height of the connector can significantly enhance the double-layered system’s protective performance, which has practical significance in protecting vulnerable masonry wall in frame structure from blast loads.

Double-Layer Energy Management for Multi-Motor Electric Vehicles

This paper proposes a double-layer energy management system (EMS) for electric vehicles driven by multiple permanent magnet synchronous motors. The system minimizes energy consumption and ensures safe longitudinal motion. The inner-layer distributes torques and flux currents by minimizing the motor input power. The outer-layer generates the total torque command by controlling the aggregated motor speed via a disturbance observer-based controller. A design condition that sufficiently guarantees the system's L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> stability is presented. The condition is independent of the torque distribution ratios and can be checked conveniently via passivity notation without linearizing the total system. Various validation tests were performed using a three-wheel recreational electric vehicle (EV) platform. The advantage of the double-layer EMS has been compared with several EMSs proposed recently in the literature. Critical testing scenarios were employed, including sharp change in road friction during high acceleration. Test results reveal that, regardless of such condition, the double-layer EMS can prevent the wheel slip, thereby significantly reducing energy consumption. The New European Driving Cycle test was also conducted to demonstrate the merit of simultaneously optimizing torque distribution ratios and motor flux-currents.

Sustainable sponge-like composite hydrogel evaporator for highly efficient solar steam generation

Solar steam generation (SSG) using a hydrogel-type solar evaporator has emerged as one of the most expedient approaches for producing clean water to address the issue of water scarcity at a global level. In this work, we developed a stable two-dimensional (2D) spongy hybrid hydrogel using partially hydrolyzed polyvinyl alcohol (PVA) and δ-MnO2 nanosheet (a solar absorber) in a simple and cost-effective method. Water-uptake capillaries in the 2D hydrogel have been effectively modified by optimizing the volume of the cross-linker, which in turn facilitates a balanced water transport speed and the heat localization ability of the solar absorber and hence the evaporation rate. Simultaneously, the 2D planar hydrogel is transformed into a three-dimensional (3D) spiral and cylinder-shaped evaporator, and its evaporation efficiency was tested employing a water contactless double-layer interfacial evaporating system. A prototype SSG system showed an evaporation rate of 1.56 kg/m2/h, 3.33 kg/m2/h, and 3.63 kg/m2/h corresponding to a solar to vapor conversion efficiency of 78%, 166%, and 181% respectively, for a 2D planar, 3D spiral and cylinder-shaped evaporator under 1 sun. The surface temperature was always below the environmental temperature during the illumination period, which helped the 3D systems absorb energy from the environment. This led to cold vaporization with zero energy loss and thus enhanced the efficiency of the 3D configurations compared to 2D. Furthermore, the designed double-layer evaporator maintained consistent long-term performance with antifouling and salt rejection properties and ensured clean water production from sewage and seawater.

Drag resistivity in double-layer gapped graphene structures

We study the frictional drag phenomenon in a double-layer system made of two parallel gapped graphene layers by calculating the Coulomb drag resistivity. The random-phase approximation is employed to determine the polarizability functions of layers and the frequency-dependent dielectric function of the structure. Our computations illustrate that the Coulomb drag resistivity in double-layer gapped graphene systems show some interesting different features, compared to that in other double-layer ones. Coulomb drag resistivity in the system steadily increases as temperature increases but quickly decreases with the increase in interlayer distance. With small interlayer separations, the drag resistivity behaves as a smoothly increasing function of the bandgap. Nevertheless, with sufficiently large separations, the Coulomb drag resistivity increases with small bandgaps but decreases with larger ones. We observe that a finite bandgap has remarkable contributions to the frictional drag phenomenon, therefore it is necessary to take into account this factor in calculations to make better agreements with experimental works.

Switching the Symmetry of Graphene Plasmons with Nanoemitters for Ultimate Infrared-Light Confinement

Vertical plasmonic coupling in double-layer graphene leads to two hybridized plasmonic modes: optical and acoustic plasmons with symmetric and anti-symmetric charge distributions across the interlayer gap, respectively. However, in most experiments based on far-field excitation, only the optical plasmons are dominantly excited in the double-layer graphene systems. Here, we propose strategies to selectively and efficiently excite acoustic plasmons with a single or multiple nano-emitters. The analytical model developed here elucidates the role of the position and arrangement of the emitters on the symmetry of the resulting graphene plasmons. We present an optimal device structure to enable experimental observation of acoustic plasmons in double-layer graphene toward the ultimate level of plasmonic confinement defined by a monoatomic spacer, which is inaccesible with a graphene-on-a-mirror architecture.

Characterization of Interlayer Bonding Mechanism Based on Interface Morphology in Double-Layered Asphalt Systems

The mechanism of interlayer bonding and its relationship with interface morphology in asphalt pavement is not well understood yet. This study aims at investigating the effect of interface morphology on the interlayer bonding performance of double-layered asphalt systems. Four double-layered asphalt systems were prepared with rubberized asphalt concrete (RAC), asphalt concrete (AC), and stone mastic asphalt (SMA) mixtures. To test the influence of different interlayer treatments, three conditions were studied: styrene-butadiene-styrene (SBS)-modified asphalt gravel seal (GS) coat (SBS-GS), rubber-modified asphalt gravel seal coat (RA-GS), and fiber-reinforced rubber–modified asphalt gravel seal coat (FR-GS). The influence of surface type and interface treatment on interface morphology and bonding properties were compared and analyzed using a series of indoor interlayer shear bonding tests under three temperature conditions in two phases. In addition, based on the three-dimensional (3D) scanning and reconstruction technique, the morphology of the nondestructively separated interface of double-layered systems with no interlayer treatment was obtained, and the mechanism of the influence of the interface morphology on the interlayer shear strength was analyzed in depth. The results showed that double-layered systems exhibited different macrotexture and roughness characteristics at interlayer surfaces, creating distinct interface morphology properties for each system type. Consequently, the interlayer bonding strength and performance of double-layered asphalt systems were affected accordingly. In this respect, the order of the interlayer shear strength of double-layered systems with different interlayer treatments at different temperatures ranked as RAC-13/RAC-20 > SMA-13/RAC-20 > SMA-13/AC-20 > AC-13/AC-20. It was demonstrated that the proposed interface area ratio (K) can be used for the characterization of the interface morphology and reflect the interlayer bonding state. Moreover, it was found that the interlayer treatment could influence the interface morphology to a certain extent and change the effective bonding between layers. As a result, the order of interlayer shear strength of different interlayer bonding treatments ranked as FR-GS> RA-GS > SBS-GS. Finally, aggregate gradation of the mixtures could also affect the morphological characteristics of the interface.

Phosphorus Removal in VFCWs with Lightweight Aggregates Made of Fly Ash from Sewage-Sludge Thermal Treatment (FASSTT LWA)

This study analyzed the effect of lightweight aggregates made of fly ash from sewage-sludge thermal treatment (FASSTT LWA) on the effectiveness of phosphorus removal from wastewater in vertical constructed wetlands (CWs), depending on FASSTT LWA content in the CW filling and hydraulic loading rate. It was performed over 13 weeks using 15 lysimeters prepared as double-layer systems. An upper layer was made of FASSTT LWA above the gravel layer with different thicknesses of FASSTT LWA (CW 0 cm: only gravel; CW 12 cm, CW 25 cm; CW 50 cm, and CW 100 cm: only FASSTT LWA). Each filling variant was repeated three times. Wastewater with a mean phosphorus concentration of 7.43 mgP/L was fed to the lysimeters once a day. The hydraulic loading rates tested were 3.0, 5.0, and 7.0 mm/d. Both the increased FASSTT LWA content in the CW filling and the decreasing hydraulic loading rate were found to boost the effectiveness of phosphorus removal in the treated wastewater. Constructed wetland filled in 100 % with FASSTT LWA ensured a reduction in phosphorus concentration below 2.0 mg P/L at all hydraulic loading rates tested.

Optimasi sistem kultur dan media untuk peningkatan tinggi tunas in vitro kelapa sawit

Optimization of in vitro shoot growth is necessary to shorten the culture time and produce vigorous oil palm plantlets. This research was conducted to determine the best media and culture techniques to accelerate in vitro shoot growth of oil palm. Shoots of oil palm derived from somatic embryogenesis were grown on DF media with two culture systems (solid medium and double-layer) combined with hormone treatments (0.5-1 mg L-1 giberellin/GA3 and 0.5 mg L-1 Benzyl amino purine/BAP or thidiazuron/ TDZ). Further optimization was conducted using different bottle closures (polypropylene screw caps and plastic wraps) and macronutrients (standard or double concentrations). This research was conducted using a completely randomized design (CRD), with each treatment consisting of 5 bottle replications and each bottle consisting of 5 shoots. The results showed that media with double-layer system combined with GA3 (0.5-1 mg L-1) and TDZ (0.5 mg L-1) gave the highest shoot height increment. The use of double-strength macronutrient media combined with screw bottle caps increased shoot height (136-167 %) and decreased shoot tip necrosis (0-24 %). Plastic wrap bottle caps increased shoot tip necrosis (STN), while doubling macronutrients reduced STN. The growth of oil palm shoots began to slow down after 5 weeks of culture. In conclusion, the optimal conditions for in vitro shoot growth of oil palm were at usage of double-layer media added with GA3 0.5-1 mg L-1, TDZ 0.5 mg L-1, and double macronutrients on bottle jars with polypropylene screw caps.