A matching model for Construction subcontractor selection in Engineering bid decisions using Ordinal priority approach

In recent years, the two-sided matching theory has been applied in various fields. Its influence in the engineering field is becoming more and more significant. In the construction engineering context, from the contractor’s perspective as the decision-maker, the mutual matching between project bidding and subcontractors is a complex and uncertain process. A suitable matching method needs to be selected according to the particular situation. Since this study requires considering both the highest satisfaction of parties and the weight of individual fulfillment, we use the two-sided matching theory to address the mutual matching between the engineering project bidding and subcontractor. At the same time, the Ordinal Priority Approach (OPA) is employed to determine the weights and evaluate the indicators of both parties and then determine the preference between the two parties, effectively avoiding the deviation caused by subjective influence in the process. As a result, a bilateral matching model is proposed with the highest satisfaction and considering individual satisfaction. Finally, an example is presented to verify the feasibility and effectiveness of the proposed model

Green Protective Geopolymer Coatings: Interface Characterization, Modification and Life-Cycle Analysis

In the interest of solving the resource and environmental problems of the construction industry, low-carbon geopolymer coating ensures great durability and extends the service life of existing infrastructure. This paper presents a multidisciplinary assessment of the protective performance and environmental impacts of geopolymer coating. Various parameters, such as main substance, water-solid (W/S) ratio, activator type and curing time, were investigated for their effects on interface characterization in terms of contact angle, surface energy, mechanical properties and microstructure. These parameters had negligible effects on the amounts and types of hydrophilic functional groups of geopolymer surfaces. A combination of organic surface modifiers and geopolymer coatings was shown to ensure hydrophobic surface conditions and great durability. Silicon-based modifiers exhibited better wetting performance than capillary crystalline surfactants by eliminating hydroxyl groups and maintaining structural backbone Si-O-T (Si, Al) on geopolymers’ surfaces. Finally, life-cycle analysis was conducted to investigate the environmental performance. Geopolymer coating yielded substantially lower environmental impacts (50–80% lower in most impact categories) than ordinary Portland cement (OPC) coating. Silicon-based modifiers had negligible influence due to their minimal usage. Increasing the W/S ratio diluted the geopolymer coating and decreased the environmental impacts, and slag-based geopolymer coating achieved lower environmental impacts than FA-based and MK-based varietie

Aqueous Stable Ti 3 C 2 MXene Membrane with Fast and Photoswitchable Nanofluidic Transport

High, stable, and modulatable ionic conductivity is important for many nanofluidic applications of layered two-dimensional (2D) membranes. In this study, we demonstrate a proton and ionic conductivity of the Ti 3 C 2 T x membrane that is orders of magnitude higher than that of bulk solution at low concentrations. Importantly, the membrane is highly stable in aqueous solution without any modification, due to the strong and attractive interlayer van der Waals interaction and weak electrostatic repulsive interaction. Furthermore, by exploiting the intrinsic photothermal property of MXene, we demonstrate that the ionic conductivity can be reversely, rapidly, and completely switched on or off with laser light. This study should prove MXene membrane as a suitable platform to study and utilize nanofluidic ion transport. It should also inspire future studies to manipulate the mass transport through 2D membranes using their inherent physicochemical properties

Mechano-Electrochemically Promoting Lithium Atom Diffusion and Relieving Accumulative Stress for Deep-Cycling Lithium Metal Anodes

Lithium metal batteries (LMBs) can double the energy density of lithium ion batteries. However, the notorious lithium dendrite growth and large volume change are not well addressed, especially under deep-cycling. Here, w e build an in-situ mechanical-electrochemical coupling system and find that tensile stress can induce smooth lithium deposition. Density functional theory (DFT) calculation and finite element method (FEM) simulation confirm the lithium atom diffusion energy barrier can be reduced when the lithium foils are under tensile strain. W e then incorporate tensile stress into lithium metal anodes by designing an adhesive copolymer layer attached to lithium in which the copolymer thinning can yield a tensile stress to the lithium foil. W e further prepared elastic lithium metal anode (ELMA) via introducing a 3D elastic conductive polyurethane (CPU) host for the copolymer-lithium bilayer to release accumulated internal stresses and resist volume variation. The ELMA can withstand hundreds of repeated compression-release cycles under 10% strain. LMBs paired with the ELMA and LiNi0.8 Co0.1 Mn0.1 O2 (NCM811) cathode can operate beyond 250 cycles with 80% capacity retention under practical condition of 4 mAh cm-2 cathode capacity, 2.86 g Ah-1 electrolyte-to-capacity ratio (E/C) and 1.8 negative-to-cathode capacity ratio (N/P), 5 times of the life time using lithium foils. This article is protected by copyright. All rights reserved

Vertically Heterostructured Solid Electrolytes for Lithium Metal Batteries

Solid-state electrolytes (SSEs) have been regarded as the most attractive candidate for safe and high-energy lithium (Li) batteries of the next generation. However, the inability of current SSEs to keep up with the performance requirements of batteries is significantly affected by complex factors, especially ionic conductivity, mechanochemical properties, and coupled ion/electron reaction at the electrified interfaces. Strategies in solid electrolyte chemistries and technologies are put forward to overcome these challenges while widening the breadth of possible applications. Among them, vertically heterostructured solid-state electrolytes (HSE) are constructed as a most promising strategy, which can take advantage of individual SSE layers together and rationalize the stability and compatibility of electrodes. This review comprehensively summarizes the specific features of the HSE based on the current knowledge of SSE failure modes. Additionally, a detailed review of the recent progress on the HSE design in terms of organic polymer electrolytes and inorganic electrolytes is generated. Finally, the advantages and drawbacks of the design strategies are discussed. New perspectives about HSE are proposed as well

Porous Al Current Collector for Dendrite-Free Na Metal Anodes

Na-based batteries are proposed as promising energy storage candidates for beyond Li-ion technology due to the higher natural earth of Na metal. For its high capacity and low potential, Na metal may carve itself a niche when directly used as anodes. Similar to or even more problematic than Li, however, uneven plating/stripping of Na leads to dendrite formation. As the plating substrates, current collectors have a paramount influence on the Na plating/stripping behaviors. Here we propose porous Al current collectors as the plating substrate to suppress Na dendrites. Al does not alloy with Na. It is advantageous over Cu current collectors in terms of cost and weight. The interconnected porous structure can increase available surface for Na to nucleate and decrease the Na⁺ flux distribution, leading to homogeneous plating. The Na metal anodes can run for over 1000 cycles on porous Al with a low and stable voltage hysteresis and their average plating/stripping Coulombic efficiency was above 99.9%, which is greatly improved compared to planar Al. We used the porous Al for Na–O₂, Na–Na₃V₂(PO₄)₃ cells with low Na amount and anode free Na–TiS₂ batteries and anticipate that using this strategy can be combined with further electrolyte and cathodes to develop high performance Na-based batteries