20 research outputs found

    Research on the protection and reuse of industrial heritage from the perspective of public participation—a case study of northern mining area of Pingdingshan, China

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    With the decline of the big industrial period, many industrial cities in China are facing the problem of urban transformation. Post-industrial economic activities and social life often replace the demand for land and population growth, and the particular type of cultural heritage of industrial heritage is often abandoned and decayed. Recent domestic and foreign research has responded to this problem and sought to provide solutions for the protection and reuse of industrial heritage. Despite some progress, the advice and feelings of ordinary citizens are often rarely considered, or how local urban characteristics become the core of urban reconstruction. To solve this problem, the focus of this study is the case study of Pingdingshan City. Pingdingshan is an industrial city with coal as its core industry. Shortly, the problem of industrial heritage will be a severe problem facing the city. The study included research designs and methods for collecting data from field observations, questionnaires, interviews, and literature studies. In the process, researchers have critically considered the importance and implications of public participation in exploring the way in which they are protected and reused through the protection and reuse of industrial heritage. It is particularly worth mentioning that in the reconstruction of the protection and reuse of industrial heritage in Pingdingshan, government officials and enterprises lack sensitivity to local conditions and the views of residents. The study concluded that the protection and reuse of industrial heritage require public participation and that the public’s demands can guide and determine the way industrial heritage is protected and reused

    Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

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    Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30M⊙M_{\odot} for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

    Effects of Freeze–Thaw Cycles on the Internal Voids Structure of Asphalt Mixtures

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    Freeze–thaw cycle is one of the main distresses of asphalt pavement, and the law of freeze–thaw damage has always been an important topic. In this paper, X-ray computed tomography (CT) of asphalt mixture before and after freezing and thawing was carried out, and its two-dimensional (2D) digital image was recognized. Firstly, the eigenvalues of internal voids of asphalt mixture are extracted. Then the distribution of internal voids was analyzed. Finally, the evolution law of internal voids was summarized. The research results show that the characteristic mean value of the 9th cycle is the irreversible limit of freeze–thaw damage, and the non-resilience after the large void area increases is the fundamental reason for the accumulation of freeze–thaw damage. The source of void damage shifts from large voids to small voids, and the middle-stage is a critical stage of freeze–thaw damage. This work quantitatively evaluates the internal freeze–thaw damage process of asphalt mixture, and a morphological theory of the evolution of void damage based on an equivalent ellipse is proposed, which is helpful for better understanding the freezing–thawing damage law of asphalt pavement

    Investigations on Adhesion Characteristics between High-Content Rubberized Asphalt and Aggregates

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    The use of waste tires to prepare rubberized asphalt has been a hot trend in recent years, and the characteristics of adhesion between rubberized asphalt and aggregates are important factors affecting the performance of asphalt pavement. However, there is a lack of uniform results on the adhesion characteristics of rubberized asphalt. Therefore, crumb-rubber-modified asphalt (CRMA) with 15%, 20%, and 25% rubber contents was prepared in this work, and the basic rheological parameters and cohesive energy of the rubberized asphalt were characterized by DSR. The adhesion properties between rubberized asphalt and aggregates were characterized based on macroscopic binder bond strength (BBS), surface free energy (SFE) theory, and nanoscale atomic force microscopy (AFM) tests. The results show that crumb rubber (CR) can improve the high-temperature elastic properties of asphalt; secondly, CR can have a negative impact on the maximum tensile strength of asphalt and aggregates. CR can improve the SFE parameter of asphalt. The work of adhesion of rubberized asphalt and limestone is the highest, followed by basalt and, finally, granite. Finally, CR can cause the catanaphase in asphalt to gradually break down and become smaller, and the adhesion of rubberized asphalt can be reduced. Overall, CR can reduce the adhesion performance of asphalt, and this work provides a reference for the application of rubberized asphalt

    Self-healing properties of steel slag asphalt mixture based on experimental characterization and 3D reconstruction

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    Asphalt pavement is susceptible to cracking which affects its service life. And self-healing technology helps to heal micro-cracks in mixture at an early stage, but its mechanism of action at the mesoscale is still unclear. Therefore, the composition of steel slag asphalt mixture (SSAM) was designed, microwave heating performance, healing performance and road performance of SSAM were investigated by laboratory experiments. Finally, the SSAM was scanned using X-ray CT for 3D reconstruction and quantitative analyses. The results show that steel slag has obvious magnetic loss characteristics; the surface temperature of SSAM designed by composition is higher under microwave heating to obtain a better healing rate, and the road performance of SSAM meets the specification requirements. The damage-healing process mainly affects voids in SSAM, and microwave healing can reduce the fractal dimension of voids to reduce the proportion of fissures; from the healing index based on voids, self-healing can reduce the average coordination number and throat number of connected voids, thereby improving the performance of SSAM by reducing permeability. The self-healing performance of SSAM is improved through its compositional design; the mesoscopic model based on void characteristics helps to refine the theory of self-healing of asphalt mixtures under microwave heating

    Performance-improved Li-O2 batteries by tailoring the phases of MoxC porous nanorods as an efficient cathode

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    Novel nitrogen-doped porous molybdenum carbide (α-MoC1−x and β-Mo2C) architectures were prepared using Mo-based metal–organic frameworks (MOFs) as the precursor. The synthesized molybdenum carbides consist of numerous nanocrystals organized into micro-sized rods with interpenetrating mesoporous-channels and macroporous-tunnels along the axial direction. When employed as the cathode catalyst for Li-O2 batteries, this dual pore configuration offers abundant active sites for the electrochemical reaction and many nucleation sites for the discharge product of Li2O2; hence, decent performances were obtained. Among the two synthesized molybdenum carbides, the α-MoC1−x electrode stands out as being better due to its lower charge transfer resistance (395.8 Ω compared to 627.9 Ω) and better O2 adsorption (binding energy of −1.87 eV of α-(111)-Mo compared to −0.72 eV of β-(101)-Mo). It delivered a high full discharge of 20 212 mA h g−1 with a discharge voltage of 2.62 V at 200 mA g−1. A good cycling stability was also obtained: i.e. 100 stable cycles with a fixed capacity of 1000 mA h g−1 (at a current density of 200 mA g−1) with a charging voltage of 4.24 V and maintaining a respectable round-trip efficiency of ∼70%.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore

    1D to 3D hierarchical iron selenide hollow nanocubes assembled from FeSe2@C core-shell nanorods for advanced sodium ion batteries

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    3D hierarchical hollow nanocubes constructed by 1D FeSe2@C core-shell nanorods were successfully prepared by a thermally-induced selenization process of their Prussian blue microcubes precursor. Such novel nanorods-based FeSe2@C hollow structures exhibit high conductivity and special structural property which provide good charge transport kinetics by facilitating the charge transfer into the inner of FeSe2 nanorods. When used as anode materials for sodium ion batteries, the hierarchically hollow nanocubes showed excellent rate performance and ultra-stable long-term cycling stability at a high current density of 10 A g−1, suggesting a good sodium-ion storage material. This simple solid-phase process demonstrated in this work can be further used for the preparation of other metal selenide with unique and fascinating structure for the potential applications in the energy storage field.ASTAR (Agency for Sci., Tech. and Research, S’pore)MOE (Min. of Education, S’pore

    From zinc-cyanide hybrid coordination polymers to hierarchical yolk-shell structures for high-performance and ultra-stable lithium-ion batteries

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    Uniform zinc-cyanide hybrid coordination polymer microspheres were successfully synthesized by a coprecipitation method. Then hierarchical yolk-shell structured and carbon coated ZnO microspheres (YC-ZnO) composed of ZnO@C nanocrystals were prepared by consecutive post annealing processes of these microspheres in argon and air atmosphere. Such micro-nano porous structures have the advantages of large specific surface area, good charge transport kinetics, and large cavity to accommodate the volume change and maintain the mechanical integrity of the electrode material. When evaluated as anode materials of lithium ion batteries, these ZnO yolk-shell spheres exhibited excellent battery performance with a high rate capacity and ultra-stable cycling stability.ASTAR (Agency for Sci., Tech. and Research, S’pore)MOE (Min. of Education, S’pore)Accepted versio

    Mussel Inspired Modification of Polypropylene Separators by Catechol/Polyamine for Li-Ion Batteries

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    Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields
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