196746 research outputs found
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Transport service selection and routing with carbon emissions and inventory costs consideration in the context of the Belt and Road Initiative
No full textThe Belt and Road Initiative (BRI) entails investments to improve overland (rail) transport between Europe and China. This paper introduces a microscopic Multi-Commodity Flow Service Selection Problem for freight transport under the BRI and provides a decision tool for shippers to make door-to-door service plans. The minimizing objective function considers transportation costs, in-transit inventory costs, and carbon emissions. A series of sampled data of each provincial region of China are collected from Chinese multimodal transport operators. Results show that inland regions are strongly attracted to the rail mode for shipments to Europe. However, the “last mile” (including “first mile”) transport from the shipper to the long-haul transport terminal strongly influences this choice, and carbon emissions are strongly influenced by the available last mile transport links. Under the dual impact of in-transit inventory and carbon emission costs, regions that prefer rail to maritime are much further east than suggested by previous literature
Heat Stress Indicators in Certification Schemes for the Built Environment
No full textOverheating issues in buildings have gained increased attention due to the growing frequency and severity of extreme weather events across the world due to climate change. Thus, there is a need for buildings to become resilient, being able to protect occupants from heat stress caused by heatwaves and power outages that could follow. Nowadays a variety of heat stress indicators are used to evaluate heat strain on people. This critical review study presents the comparison of different international building certification schemes with regards to their indoor heat stress indicators and assessment criteria. Six certifications are included, namely WELL, LEED, BREEAM, DGNB, RELi and HQM. The comparison concerns the relation between the indoor thermal comfort indices and the heat stress indices, and the implementation of different indicators including feasible scenarios and limits. These heat stress indicators were implemented to compare in the existing measurement data. In conclusion, LEED and RELi demonstrated the most comprehensive considerations of indoor heat stress evaluations among these certifications. An analysis on the acquired indicators on the extracted indoor environmental data of a naturally ventilated building showed that the potential of heat stress risks increased when PMV was over 1
Illuminating sustainability:A comprehensive review of the environmental life cycle and exergetic impacts of solar systems on the agri-food sector
No full textThe developing agri-food sector significantly boosts food production and plays a crucial role in resolving the global food crisis. This development is valuable when accompanied by environmental sustainability. The indiscriminate use of fossil energy sources in these industries has raised serious environmental concerns in recent years. As a result, researchers have explored the substitution of renewable energies, particularly solar energy, as a means of resource conservation. However, concerns about the environmental effects of solar technology establishment have prompted investigations into their environmental footprints. Life cycle assessment (LCA) has emerged as a valuable tool for systematically evaluating the potential environmental impacts of solar energy. Furthermore, combining LCA with exergetic analysis as the main tool for assessing energy utilization can help identify the most sustainable scenarios. In this context, the present study provides a systematic and comprehensive review and critical discussion of the environmental LCA and exergetic analysis of applied solar technologies in the agri-food sector. The study first introduces all the utilized technologies in detail. It then discusses the principles, steps, and methods of LCA and exergetic analysis employed by researchers. Based on the analysis of 116 considered studies, it is concluded that photovoltaic (PV), photovoltaic/thermal (PV/T), and concentrated solar power systems (CSP) are the leading solar technologies in the agri-food sector. The study further concludes that PV systems are the most exergoenvironmentally friendly among all solar systems, while the CSP system exhibits favorable characteristics compared to PV/T, particularly from the perspective of LCA
Life cycle assessment of lithium ion battery from water-based manufacturing for electric vehicles
No full textLithium ion batteries produced using the water-based manufacturing processes, as a greener technology, have great potential to be used in future electric vehicles (EVs). A cradle-to-grave life cycle assessment model configured for actual EV applications has been developed for the water-based manufactured lithium nickel manganese cobalt oxide (NMC)-graphite battery pack. Experimental and modeling results cover raw material extraction and processing, water-based battery manufacturing processes, battery usage during EV driving, and direct recycling at End-of-Life. The ReCiPe method is employed to investigate the environmental impacts of the water-based battery pack and benchmark it against the impacts of a conventional N-methyl-2-pyrrolidone (NMP)-based battery pack with the same mass. The cradle-to-grave energy consumption of the studied water-based battery pack is 0.976 MJ/km EV driving, equivalent to a 4.5% reduction over the NMP-based battery pack. Aside from energy usage, we find reductions in all environmental impact categories (3.0%∼85%) compared to the conventional battery pack
Investigation of higher-harmonic wave loads and low-frequency resonance response of floating offshore wind turbine under extreme wave groups
No full textWhen floating offshore wind turbines (FOWT) encounter extreme waves in operation, it is a highly nonlinear system involving floater motion and extreme wave–structure interactions. The behavior is crucial for floating offshore wind turbine safety. With the aid of a high-fidelity CFD solver, a harmonic separation method through a ‘Stokes-like’ formulation was adopted to obtain the parameters for each harmonic response. The present study focuses on analyzing higher harmonic load, dynamic motion response, and tension load of the mooring line the DeepCwind semi-submersible FOWT. The results show that the higher-harmonic wave load cannot be ignored in the extreme marine environment, the second harmonic can be over 16% of the linear wave load, and the third harmonic can be over 10% of the linear wave load with large wave steepness. The duration of a focused wave crest interaction with the platform is a short process of only 1.4 s in model scale, corresponding to about 10 s for the prototype. The wave runup at the upstream column is larger than the other columns, and the flow velocity is double that of the wave without the floater in presence. The dynamic response of the floater contains two phases, ’forced oscillations’ is identified to be drag-driven from odd harmonics, and ’free decay’ mainly comes from second-order difference-frequency influence from even harmonics. The properly normalized wave forces of surge and heave motion are not influenced by steepness kp Alinear. For surge motion, the total motion mainly comes from the nonlinear low frequency component. For pitch motion, the linear response is dominant in small kp Alinear. When the steepness kp Alinear increases gradually, the second-order low-frequency response of pitch motion will increase rapidly and dominate the total response.<br/
Hybrid substitution workflows should accelerate the uptake of chemical recyclates in polymer formulations
No full textChemical recycling of polymers is taking off as a circular technology, typically targeting pure recyclates. However, this is often not achieved efficiently due to high energy demand of separation and purification steps. In addition, many polymer applications have complex formulations that may be sensitive to impure feedstocks. Substitution of virgin feedstocks by complex recyclates (often containing impurities) requires a good knowledge of the structure/composition-property relations of polymer formulations. As this is often not the case, current practice relies on costly and rather inefficient enumeration experiments, or, at best, classical design-of-experiments approaches. We review the state of the art in structure-property modeling, present an example for polyurethane formulations, and propose a hybrid model-based framework. This involves a machine learning workflow for substitution problems in complex polymer formulations, combining existing data, novel reaction kinetics, structure-property models, molecular dynamics, and a minimum of experimental-analytical data where necessary, to build and validate the model
Impact of ground gear design on catch efficiency in demersal trawl fishery
No full textThe choice of ground gear design in demersal trawls can significantly affect both catch composition and efficiency. The preference for a specific design depends on the fishing ground. In the North-Eastern Mediterranean, two types of ground gears, Single Line and Double Line are commonly used. Therefore, this study compared the catch performance for trawls using these ground gears during research trials in the Mersin Bay multi-species demersal trawl fishery. Results showed a significant reduction in catch efficiency for common sole (Solea solea) and lizardfish (Saurida lessepsianus) with more juveniles and target-sized individuals being released by the Double Line trawl compared to the Single Line trawl. Contrary, no difference was obtained for red mullet (Mullus barbatus) between the two gears. The present study demonstrates that ground gear design can affect species and size composition in demersal trawl fisheries. Therefore, ground gear design should be considered in the fisheries regulations as well as for demersal sampling trawl configurations
Radiative intensity regulation to match energy conversion on demand in solar methane dry reforming to improve solar to fuel conversion efficiency
No full textThe mismatch between radiative intensity field and energy required for solar thermochemical reaction can cause serious heat waste and reduce energy conversion efficiency. To improve the energy conversion efficiency of solar to fuel, the radiative intensity regulation method to match energy conversion on demand in solar methane dry reforming is proposed by this study. The design of solar spots and biomimetic leaf hierarchical porous structures is investigated and optimized, which can realize a better radiative intensity field matching. The experimental and numerical studies show that, by regulating radiative intensity field to match energy conversion on-demand in solar thermochemical reactor, the methane conversion rate and solar thermochemical energy storage efficiency can be increased by 4.6% and 6.1%, respectively. The ideal synergy between real temperature field distribution and theoretical temperature requirement is perfectly achieved
Co-optimization of passive building and active solar heating system based on the objective of minimum carbon emissions
No full textAt present, both active and passive solar heating system designs rely on the sequential design method. However, this method fails to account for the correlation between passive components and active systems, leading to poor synergy between passive solar technology and active heating systems. Therefore, a collaborative simulation model of active and passive solar heating systems was constructed in this study. In addition, an optimization model with the objective of minimization carbon emissions of buildings and the active system was developed, and the sunspace depth, building envelope parameters, and the equipment capacity were optimized and simulated. The results indicate that the optimized total carbon emissions of solar active and passive heating systems can be reduced by up to 26.5%–50.3% compared to passive building and boiler combined systems. The optimized solar fraction of solar active and passive heating systems exceeds 85%. Furthermore, higher energy efficiency of heat source equipment in the active system has been related to a lower thermal insulation performance of the enclosure structure and a greater building load undertaken by the active system. In the active solar heating system, the higher the efficiency of the auxiliary heat source, the more the heating load is borne
Direct recycling of lithium ion batteries from electric vehicles for closed-loop life cycle impact mitigation
No full textDirect recycling of lithium ion batteries from electric vehicles aims to close the loop of battery manufacturing. This study presents a novel process-based life cycle assessment model for studying the environmental impacts associated with the direct recycling for closed-loop production of lithium ion battery relative to the conventional open-loop battery manufacturing. A 66 kWh NMC-graphite battery pack is analyzed using directly recycled NMC and graphite for the closed-loop manufacturing. The results show that the closed-loop manufacturing via direct recycling can reduce environmental impacts by up to 54% over the conventional open-loop manufacturing of lithium ion battery for electric vehicles