Design and evaluation of UHPP steel bridge deck pavement for high-temperature and rainy regions

To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.

A large-area bionic skin for high-temperature energy harvesting applications

For the large amount of waste heat wasted in daily life and industrial production,we propose a new type of flexible thermoelectric generators(F-TEGs)which can be used as a large area bionic skin to achieve energy harvesting of thermal energy.With reference to biological structures such as pinecone,succulent,and feathers,we have designed and fabricated a biomimetic flexible TEG that can be applied in a wide temperature range which has the highest temperature energy harvesting capability currently.The laminated free structure of the bionic F-TEG dramatically increases the efficiency and density of energy harvesting.The F-TEGs(single TEG only 101.2 mg in weight),without an additional heat sink,demonstrates the highest output voltage density of 286.1 mV/cm^(2)and the maximum power density is 66.5 mW/m^(2) at a temperature difference of nearly 1000℃.The flexible characteristics of F-TEGs make it possible to collect the diffused thermal energy by flexible attachment to the outer walls of high-temperature pipes and vessels of different diameters and shapes.This work shows a new design and application concept for flexible thermal energy collectors,which fills the gap of flexible energy harvesting in high-temperature environment.

Highly flexible ceramic nanofibrous membranes for superior thermal insulation and fire retardancy

Ceramic membranes are attractive for thermal management applications due to its lightweight and ultralow thermal conductivity,while it is indispensable to address the long-standing obstacle of its poor mechanical stability and degradation under thermal shock.In this work,a series of the organic polymer template-modulated yttria doped zirconia(YDZ)nanofibrous membranes with lightweight,superior mechanical and thermal stability are developed through a cost-effective,scalable sol-gel electrospinning and subsequent calcination method.The YDZ membranes demonstrate excellent flexibility and foldability,which can be attributed to the tetragonal phase and small crystallite size of the YDZ fibers due to the presence of yttria.Besides,the fibrous size,grain size,mechanical and thermal stability of YDZ nanofibrous membranes could be tailored by varying the species and molecular weight of polymer template.The remarkable performances are obtained through the poly(vinyl pyrrolidone)(PVP)template YDZ nanofibrous membranes,featuring the superior tensile strength up to~4.82 MPa,excellent flexibility with bending rigidity~26 mN,robust thermal stability up to 1,200℃,ultra-low thermal conductivity of 0.008–0.023 W·m^(−1)·K^(−1)(25–1,000℃),and excellent flame retardancy with tolerance of flame up to 1,000℃.The remarkable properties can be attributed to the smaller fibrous size,and higher grain size resulting from PVP template.This robust material system is ideal for thermal superinsulation with a wide range of uses from energy saving building applications to spacecraft.