29 research outputs found

    Characterizing the generation and flows of construction and demolition waste in China

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    Abstract only. Associated with the continuing increase of construction activities such as infrastructure projects, commercial buildings, and housing programs, China has been experiencing a rapid increase of construction and demolition (C&D) waste. Till now, the generation and flows of China’s C&D waste has not been well understood. This paper aims to provide an explicit analysis of this based on a weight-per-construction- area method. Our results show that approximately 2.36 billion tonnes of C&D waste were generated in China annually during the period of 2003–2013, of which demolition waste and construction waste contributed to 97% and 3%, respectively, in 2013. East China contributed over half of the total C&D waste in China due to their rapid economic development and expansion of cities, followed by Middle China (21%) and South China (11%). Potential economic values from the recycling of C&D waste were found to vary from 201 billion (the worst scenario, i.e., the current practice of C&D waste management) to 401 billion US dollars in 2013 (the most optimistic scenario, i.e., C&D waste is assumed to be well recycled); and the landfill space demands were estimated to range from 7504 millionm3 (the worst scenario) to 706 mil- lionm3 (the most optimistic scenario) accordingly. Consequently, increasing the recycling rate and reducing landfill rate of C&D waste could not only improve the potential recycling economic values, but also dramatically reduce land use and potential environmental impacts

    'Blue Route' for combating climate change

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    BT/Environmental Biotechnolog

    Design and assessments on a hybrid pin fin-metal foam structure towards enhancing melting heat transfer: An experimental study

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    Solar energy, as a kind of renewable energy, offers a large reserve to be harvested at a reasonably low cost for engineering applications. To decouple the temporal and spatial relevance of the continuous energy supply of solar energy, latent heat thermal energy storage can deal with this problem at different temperatures. Aiming to improve energy efficiency, a novel hybrid metal foam-pin fin structure is designed and assessed. Upon conducting measurements on a well-designed experimental bench, the phase change processes of paraffin that is filled in fins, metal foam, and a combination of both (hybrid structure) are evaluated. During the experiments, the transient melting interface is snapshotted and temperature development is documented under five different heat source temperatures of 61 °C, 63 °C, 65 °C, 68 °C, and 70 °C. In the foreground of the novel hybrid structure, each segment of the hybrid is also justified and discussed. Results indicate that the hybrid structure augments marked heat transfer. Compared to pure PCM, complete melting time decreases by 63.4% and simultaneously the temperature response rate increases by 143.9% as implementing the hybrid. Attempts to design hybrid structure find a solution to assess and operate thermal storage applications for solar engineering.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Process and Energ

    Effect of porosity variation strategy on the performance of functionally graded Ti-6Al-4V scaffolds for bone tissue engineering

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    Functionally graded scaffold (FGS) is designed to mimic the morphology, mechanical and biological properties of natural bone closely. Porosity variation strategy between different regions in FGS plays a crucial role in influencing its mechanical and biological performance. A combination of modeling tool and scripting language can effectively enhance the ability to optimize FGS design. This study was aimed at determining the effect of porosity variation strategy on the mechanical performance and permeability of the as-built and as-heat-treated FGSs. Ti-6Al-4V FGSs with sizes of 10 × 10 × 15 mm and diamond lattice structures were designed and fabricated by means of selective laser melting. A wide range of porosities in the FGSs (38–75%) were achieved by applying six different porosity variation strategies. The elastic modulus (3.7–5.7 GPa) and yield strength (27.1–84.7 MPa) of the as-built FGSs were found to vary between the corresponding mechanical properties of cancellous bone and cortical bone. Heat treatment reduced the strengths by 13–56%. Porosity variation strategy strongly affected the deformation behavior and failure mechanisms of the FGSs. The sigmoid function-controlled FGSs showed gradual failure behavior and sample Sigk0.5b8 showed superior overall performance. The results demonstrated that porosity variation strategy is a feasible means for tailor design of FGS.Accepted Author ManuscriptBiomaterials & Tissue Biomechanic

    The application model of 3D cadastre in practical registration for real estate in China

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    Since the introduction of the concept of 3D cadastre, a great many of significant research results have been done. To promote the development of 3D cadatre, 3D cadastre working group sponsored by International Federation Surveyors (FIG) commissions 3 and 7 was organized by Delft University of Technology in 2001. This working group provides a research and communication platform for the 3D cadastral researchers in the world. With the development of 3D cadastre in recent decades, a great many of technologies including 3D cadastral data acquisition, data validation, data visualization and so on have been developed, which met the basic needs of 3D cadastre. Furthermore, 3D cadastre management systems had been carried out in service in several countries and regions include Queensland in Australia, the Netherland, Sweden, and so on. Compared with the above countries and regions, 3D cadastral development in China is relatively backward. Lots of theoretical researches include the data modeling and the register frameworks of 3D cadastre were made by Chinese researchers. However, most of the existing studies are carried out from the perspective of theoretical and with few associated practical applications in cadastral registration and management. The purpose of developing 3D cadastre is to better serve the needs of cadastral management. With the development of nowadays socio-economic, demands for 3D cadastral visualization, multi-purpose real estate registration and other 3D cadastral data services are increasing. This paper mainly introduces the ideas and parts of research results of a joint research project launched by Nanjing Normal University and Bureau of Land and Resources of Xinyi recently. The project is also supported by the Department of Land and Resources of Jiangsu and Bureau of Land and Resources of Xuzhou. The aim of the project is to establish a 3D cadastral management, data visualization and registration model for cadastral management and apply them in regional registration. Firstly, we review the real estate registration development history as the background of this project. Secondly, problems and public complaints refer to current cadastral registration are analyzed as the demands for 3D cadastral management and registration. A 3D cadastral modeling method adapted to practical demands is briefly introduced at last

    Combined effects of photoaging and natural organic matter on the colloidal stability of nanoplastics in aquatic environments

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    The transport and fate of nanoplastics (NPs) in aquatic environments are closely associated with their colloidal stability, which is affected by aging and natural organic matter (NOM) adsorption. This study systematically investigated the combined effects of photoaging and NOM (e.g. humic acids, HA; and a model protein, bovine serum albumin, BSA) on the aggregation kinetics of NPs (polystyrene, PS) in NaCl and CaCl2 solutions. Our results showed that photoaged NPs adsorbed less HA than pristine NPs due to weaker hydrophobic and π-π interactions. In return, HA showed weaker impacts on NPs’ stability after photoaging. Differently, photoaged NPs absorbed more BSA than pristine NPs due to stronger hydrogen bonding and electrostatic attraction. Thus, the inhibitory effects of BSA on the aggregation kinetics of NPs were enhanced after photoaging. Regarding the effects of NOM on the aging of NPs, our results showed that HA competed with NPs for photons and underwent photo-degradation. Subsequently, the destruction/reconstruction of adsorbed HA increased (in NaCl) or decreased (in CaCl2) the stability of NPs. Notably, light radiation-induced flocculation of BSA molecules, which wrapped and integrated NPs and lead to their destabilization. Overall, this study provided new insights into the aggregation behavior of NPs in aquatic systems, which have significant implications for predicting the transport and fate of NPs in complex real-world environments.Sanitary Engineerin

    Toward Carbon-Neutral Water Systems: Insights from Global Cities

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    Many cities have pledged to achieve carbon neutrality. The urban water industry can also contribute its share to a carbon-neutral future. Using a multi-city time-series analysis approach, this study aims to assess the progress and lessons learned from the greenhouse gas (GHG) emissions management of urban water systems in four global cities: Amsterdam, Melbourne, New York City, and Tokyo. These cities are advanced in setting GHG emissions reduction targets and reporting GHG emissions in their water industries. All four cities have reduced the GHG emissions in their water industries, compared with those from more than a decade ago (i.e., the latest three-year moving averages are 13%–32% lower), although the emissions have “rebounded” multiple times over the years. The emissions reductions were mainly due to various engineering opportunities such as solar and mini-hydro power generation, biogas valorization, sludge digestion and incineration optimization, and aeration system optimization. These cities have recognized the many challenges in reaching carbon-neutrality goals, which include fluctuating water demand and rainfall, more carbon-intensive flood-prevention and water-supply strategies, meeting new air and water quality standards, and revising GHG emissions accounting methods. This study has also shown that it is difficult for the water industry to achieve carbon neutrality on its own. A collaborative approach with other sectors is needed when aiming toward the city’s carbon-neutrality goal. Such an approach involves expanding the usual system boundary of the water industry to externally tap into both engineering and non-engineering opportunities.Sanitary Engineerin

    Temperature-sensing performance of polymer-derived SiAlCN ceramics up to 1000 °C

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    Temperature sensors that can operate in high-temperature and harsh environments are highly desired. However, this is a great challenge for sensing materials to operate under extreme working conditions because of oxidation and/or corrosion at high temperature. In this study, polymer-derived SiAlCN ceramics were prepared as sensing materials to overcome the abovementioned issues. A SiAlCN ceramic temperature sensor was designed and fabricated, and it performed excellent temperature-sensing properties with high accuracy, high stability, and high repeatability up to 1000 °C. Compared with traditional thermocouples, the SiAlCN ceramic sensor exhibited a faster response rate (a shorter response time). These results showed that SiAlCN ceramic is a promising sensor material for temperature measurement in high-temperature and harsh environments.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Applied Radiation & Isotope

    Building water quality deterioration during water supply restoration after interruption: Influences of premise plumbing configuration

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    Premise plumbing plays an essential role in determining the final quality of drinking water consumed by customers. However, little is known about the influences of plumbing configuration on water quality changes. This study selected parallel premise plumbing in the same building with different configurations, i.e., laboratory and toilet plumbing. Water quality deteriorations induced by premise plumbing under regular and interrupted water supply were investigated. The results showed that most of the water quality parameters did not vary under regular supply, except Zn, which was significantly increased by laboratory plumbing (78.2 to 260.7 µg/l). For the bacterial community, the Chao1 index was significantly increased by both plumbing types to a similar level (52 to 104). Laboratory plumbing significantly changed the bacterial community, but toilet plumbing did not. Remarkably, water supply interruption/restoration led to serious water quality deterioration in both plumbing types but resulted in different changes. Physiochemically, discoloration was observed only in laboratory plumbing, along with sharp increases in Mn and Zn. Microbiologically, the increase in ATP was sharper in toilet plumbing than in laboratory plumbing. Some opportunistic pathogen-containing genera, e.g., Legionella spp. and Pseudomonas spp., were present in both plumbing types but only in disturbed samples. This study highlighted the esthetic, chemical, and microbiological risks associated with premise plumbing, for which system configuration plays an important role. Attention should be given to optimizing premise plumbing design for managing building water quality.Sanitary Engineerin

    Developing equations to explore relationships between aggregate stability and erodibility in Ultisols of subtropical China

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    A soil aggregate represents a key soil structural unit that influences several physical soil properties such as water infiltration, runoff and erosion. The relationships between soil aggregate stability and interrill and rill erodibility are critical to process-based erosion prediction models yet remain unclear, likely due to the difficulty of distinguishing between interrill and rill-eroded sediment during the erosion process. This study was designed to partition interrill and sill erosion rates and relate them to the aggregate stability of Ultisols in subtropical China. Six kinds of rare earth elements (REEs) were applied as tracers mixed with two cultivated soils developed over Quaternary red clay or shale at six slope positions. Soil aggregate stability was determined by the Le Bissonnais (LB)-method. Simulated rainfall of three intensities (60, 90 and 120 mm h(-1)) was applied to a soil plot (2.25 m long, 0.5 m wide, 0.2 m deep) at three slope gradients (10 degrees, 20 degrees and 30 degrees) for a duration of 30 min after runoff initiation. The results indicated that rill and interrill erosion rates in the soil developed over shale were considerably greater than those in the soil developed over Quaternary red clay. Equations using an aggregate stability index A(s) to replace the erodibility factor of interrill and rill erosion in the Water Erosion Prediction Project (WEPP) model were constructed after analysing the relationships between estimated and measured rill and interrill erosion data. The results show that these equations based on A, have the potential to improve methods for assessing interrill and rill erosion erodibility synchronously for subtropical Ultisols by using an REE tracing method
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