With the continuous promotion of urbanization, the generation of construction and demolition waste (CDW) is increasing. The environmental problems and safety hazards caused as a result need to be resolved. In this paper, based on the system dynamics (SD) theory, the modeling, the cost, and the environmental benefit of CDW resource management under the life cycle assessment (LCA) are proposed. Specifically, we propose a combined policy derived through three variables, namely, fines, subsidies, and charges. The target is to reduce illegal dumping behavior and landfill volume and to improve the recycling volume and environmental benefits. The model is constructed with the help of the software VENSIM, and the validity and feasibility of the model are demonstrated with data from Nantong City. The results show that a single policy cannot simultaneously improve environmental benefits, illegal dumping, recycling, and landfill behavior. A combined policy combines the advantages of three single policies, fines, subsidies, and charges, which not only can effectively curb illegal dumping and landfill disposal under the premise of prioritizing environmental benefits, but can also promote the recycling of CDW. The reasonable range for the fine is 300–350 CNY/ton; the rational range for subsidies is 30–40 CNY/ton; and the flexible range for treatment charge is 40–80 CNY/ton. The model can be used for the quantitative assessment of urban CDW management costs and environmental benefits and can also provide a theoretical basis for the government.
Phosphors-in-glass (PiGs) regarded as a promising phosphor-converter for white light emitting diodes (WLEDs) is being researched widely. However, there are few reports on the effect of changing the shape of PiGs on the color rendering index (CRI) and heat dissipation of WLEDs. In this paper, gel casting with Isobam was first attempted in preparing special-shaped PiGs successfully. It exhibited that 76 wt.% was the optimum solid content based on the rheological properties of slurry and the shrinkage of green bodies. The sintering rate should be kept at a low speed and glass transition temperature (Tg) of glass powders must be higher than sublimation temperatures (Ts) of APS and Isobam. The CRI of PiGs was increased by about 27% after changing the shape of PiGs from cylinder to dome. Most importantly, operating temperature also reduced effectively the increase of the surface area of PiGs. Therefore, changing the shape of PiGs by gel casting with Isobam is a creative way for high-power WLEDs lighting.
In this work, based on Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic and (Sr, Ca)AlSiN3:Eu2+ phosphors, novel green-light-emitting materials were systematically studied. YAG:Ce3+ transparent ceramics with different doping-concentrations, from 0% to 1% (Sr, Ca)AlSiN3:Eu2+ phosphors, were fabricated by dry pressing and vacuum sintering. The serial phosphor ceramics had 533 nm green-light emission when excited by 460 nm blue light. The PL, PLE, and chromaticity performances were measured, indicating that more of the green-light component was emitted with the increase in doping concentration. The addition of (Sr, Ca)AlSiN3:Eu2+ phosphor increased the green-light wavelength area and improved the quantum yield (QY) of the YAG:Ce3+ ceramic matrix. The phase composition, microstructure, crystal-field structure and phosphor distribution of (Sr, Ca)AlSiN3:Eu2+ phosphor-doped YAG:Ce3+ transparent ceramics were investigated, to explore the microscopic causes of the spectral changes. Impressively, (Sr, Ca)AlSiN3:Eu2+ phosphors were distributed homogeneously, and the pinning effect of phosphor caused the suppression of grain growth. The novel materials could provide an effective strategy for full-spectrum white lighting and displaying applications in the future.
The recycling of construction waste is key to reducing waste generation and CO2 emissions. This study aimed to develop a quantitative model for analyzing the carbon reduction potential of recycling construction, demolition, and renovation waste (CDRW) in Jiangsu province. The waste generation rate calculation method and nonlinear autoregressive artificial neural network model were used to estimate and predict CDRW generation. The life cycle assessment was performed to calculate the carbon reduction potential of recycling CDRW. In quantifying the carbon reduction potential, not only construction and demolition waste, but also renovation waste was considered for the first time. The results showed that the total carbon reduction potential of recycling CDRW increased from 3.94 Mt CO2e in 2000 to 58.65 Mt CO2e in 2020. Steel and concrete were the main contributors. By scenario analysis, the carbon reduction potential of fully recycling CDRW in 2020 increased by 37.79 Mt CO2e, a growth rate of 64%. The study further predicts future CDRW generation and the corresponding carbon reduction potential. Our conclusions indicate that 245.45 Mt of CDRW will be generated in 2030, and carbon reduction potential may reach 82.36 Mt CO2e. These results will help the government manage construction waste better and reach early achievement of the carbon peak target.
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