Design and research of cutting load measuring device for coal and rock

Based on the analysis of the present situation of the research on the cutting process of the drum, the research method of the equipment capable of obtaining the cutting force in the drum cutting process is proposed by combining the finite element explicit dynamic analysis. Aiming at the complicated force of the shearer’s pick cutter in cutting the coal rock. In this paper, the finite element software is used to explicit dynamics simulate the picking of coal mining in the cutting process, and the strain distribution on the cutting is determined. Based on this, the use of strain gauge bridge design ideas to indirectly obtain the force on the cutter, and finally get the relevant experimental data. Compared with the finite element simulation analysis, the feasibility of the two schemes is explained, and the foundation of the follow-up experiment is laid

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Enhanced Thermoelectric Performance of Bi2O2Se with Ag Addition

Polycrystalline Bi2O2Se/Ag nanocomposites were synthesized by spark plasma sintering process. Their thermoelectric properties were evaluated from 300 to 673 K. With the addition of silver, the conductive second phase Ag2Se and Ag can be observed, which results in a significant enhancement of electrical conductivity. The maximum conductivity is 691.8 S cm−1 for Bi2O2Se/20 vol.% Ag, which increased nearly 500 higher times than the pure Bi2O2Se bulk. ZT value can be enhanced greatly, ~0.07, for Bi2O2Se/5 vol.% Ag at 673 K, which is two times larger than the pure sample

Flexible reduced graphene oxide/polyacrylonitrile dielectric nanocomposite films for high-temperature electronics applications

Polymer dielectrics possess excellent flexibility compared with inorganic ceramic materials. However, the relatively low dielectric constant and working temperature significantly constrain their widespread application. Here, we report a low-cost facile strategy to develop flexible polymer-based composite films with high dielectric constant over a broad temperature. Polyacrylonitrile (PAN) nanofiber mats containing graphene oxide (GO) with core–shell microstructure were first prepared via coaxial electrospinning and then hot-pressed into dense composite films. It was revealed that hot-pressing assisted by a stretching force under appropriate temperature and pressure can generate local conformational changes of PAN, leading to the formation of an electroactive phase with increased dielectric constant. Meanwhile, the GO transformed into reduced graphene oxide (rGO) under heat reduction, serving as conductive nanofillers to further promote the increase of dielectric constant. Consequently, the optimized rGO/PAN composites displayed thermally stable dielectric properties with a high dielectric constant (ε′ = 23, 80 °C; ε′ = 40, 150 °C) and low loss (tan δ = 0.13, 80 °C; tan δ = 0.55, 150 °C) over a broad temperature range. This work offers an efficient method for the synthesis of flexible composite dielectric films that hold great potential in high-temperature electronic applications

Polyvinyl butyral composites containing halloysite nanotubes/reduced graphene oxide with high dielectric constant and low loss

Polymer-based composites with high dielectric constant and low loss are highly desirable due to their inherent advantages of easy processability, flexibility, and lightweight. Herein, a functional nanofillers, halloysite nanotubes (HNTs) decorated reduced graphene oxide (rGO) hybrid microstructures (HNTs@rGO) was successfully prepared via controllable electrostatic self-assembly and in-situ heat reduction method. These hybrid microstructures combine characteristics of natural 1D ceramic nanotubes with large aspect ratio and high electric conductivity of rGO micro-sheets, which provided ideal material collocation in the construction of microcapacitors. The HNTs not only effectively prevented direct contact between the rGO micro-sheets in the composites but also played an important role in forming dielectric interface within microcapacitors. Consequently, an HNTs@rGO/polyvinyl butyral (PVB) composites containing a very low content of 5wt% rGO exhibited an ultra-high dielectric constant of 150 and an extremely low loss of 0.12 at 103 Hz. It is believed that the unique characteristics and facile fabrication process of HNTs@rGO/PVB composite make it a potentially excellent candidate for flexible polymer-based dielectric materials applied in the capacitor fields

Ion-regulating Hybrid Electrolyte Interface for Long-life and Low N/P Ratio Lithium Metal Batteries

Practical lithium metal batteries (LMBs) require full and reversible utilization of limited metallic Li anodes at a solid/quasi-solid electrolyte condition. This leads to a challenging issue, i.e., how to create compatible interphases to regulate interfacial ionic transport and protect the reactive metal. Herein, to address this issue, we report a robust cellulose-based composite gel electrolyte (r-CCE) capable of stabilizing ion deposition via compositing bacterial cellulose (BC) skeleton with Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. Benefiting from the decoupled segment structure of cellulose and additional ionic channels of LLZTO, r-CCE not only achieves high ionic conductivity (1.68 × 10−3 S/cm) with a remarkable Li-ion transfer number (∼0.92) and a wide window of electrochemical stability (∼5.3 V), but also helps stabilize the Li anode. Utilizing ultrathin lithium metal anodes (15 μm), ultra-stable symmetric Li/Li cells that are armed with r-CCE demonstrate a highly stable plating/stripping process. Furthermore, a high areal capacity of ∼4.2 mAh/cm2, and 100 cycles with improved stability of the full Li metal batteries with n/p ratio of ∼0.74 are achieved

Self-Reconstructed Formation of a One-Dimensional Hierarchical Porous Nanostructure Assembled by Ultrathin TiO₂ Nanobelts for Fast and Stable Lithium Storage

Owing to their unique structural advantages, TiO₂ hierarchical nanostructures assembled by low-dimensional (LD) building blocks have been extensively used in the energy-storage/-conversion field. However, it is still a big challenge to produce such advanced structures by current synthetic techniques because of the harsh conditions needed to generate primary LD subunits. Herein, a novel one-dimensional (1D) TiO₂ hierarchical porous fibrous nanostructure constructed by TiO₂ nanobelts is synthesized by combining a room-temperature aqueous solution growth mechanism with the electrospinning technology. The nanobelt-constructed 1D hierarchical nanoarchitecture is evolves directly from the amorphous TiO₂/SiO₂ composite fibers in alkaline solutions at ambient conditions without any catalyst and other reactant. Benefiting from the unique structural features such as 1D nanoscale building blocks, large surface area, and numerous interconnected pores, as well as mixed phase anatase-TiO₂(B), the optimum 1D TiO₂ hierarchical porous nanostructure shows a remarkable high-rate performance when tested as an anode material for lithium-ion batteries (107 mA h g^–1 at ∼10 A g^–1) and can be used in a hybrid lithium-ion supercapacitor with very stable lithium-storage performance (a capacity retention of ∼80% after 3000 cycles at 2 A g^–1). The current work presents a scalable and cost-effective method for the synthesis of advanced TiO₂ hierarchical materials for high-power and stable energy-storage/-conversion devices