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Aiming at the problem of inaccurate navigation and positioning of electric forklifts in a complex environment with multiple placement racks when carrying stored crops in a warehouse, this paper proposes a combined navigation and positioning system based on information fusion of LiDAR and inertial measurement units. The method proposed in this paper improves the traditional EKF algorithm by introducing factors affecting the prior covariance matrix and changing the weights of processing old and new data in the filtering equation to achieve the desired goal of suppressing system dispersion and to accomplish accurate estimation of the position of electric forklifts in the storage room. The simulation of robot positioning and navigation in indoor environment shows that the improved algorithm improves the position estimation accuracy by about 30% compared with the traditional algorithm, the new algorithm can effectively improve the efficiency of electric forklift for handling and storage, and it can ensure the robustness of robot position estimation.

The microstructural characteristics of high thermal conductivity mesophase pitch-based carbon fibers were investigated by XRD, Raman spectroscopy, SEM and TEM. The relationship between microstructural characteristics and thermal conductivity is discussed. Results show that the radial structure is always accompanied by a splitting structure. La has more significant impact on the thermal conductivity than Lc. The Raman spectroscopy ID/IG value of the cross section was used as an essential index to evaluate the thermal conductivity of the carbon fibers. The microstructural characteristics including large graphite crystallite size, high preferred orientation along the fiber axis, and few defects contribute to the high thermal conductivity of the carbon fibers.

In the present work, a new class of 2.5D woven carbon-poly(silacetylene) composites derived from three novel poly(silacetylene) resins has been developed by VARTM process and evaluated to determine the potential for serving as advanced thermal protection material. TG analysis, PGC-MS analysis, Ar arc plasma ablation test, microstructural analysis and a ATCM have been employed to investigate the effects of chemical structures and thermal stability of poly(silacetylene) matrices on the ablation performance of their carbon fiber composites. The incorporation of rigid phenyl groups into poly(silacetylene) matrices can significantly improve the ablation-resistant performance of their carbon fiber composites, which may be ascribed to decreased pyrolysis gaseous volatiles and decreased pyrolysis residue of SiC for the poly(silacetylene) matrices during ablation, resulting in a remarkable enhancement in the mechanical spallation resistance. All the developed carbon- poly(silacetylene) composites exhibit excellent ablation-resistant performance with a recession rate ranging from 0.31 mm s−1 to 0.40 mm s−1, which would make them good candidates for advanced thermal protection materials in aerospace applications.

A three-dimensional ZrC–SiC-modified Carbon/Carbon composite having high thermal conductivity is prepared to significantly reduce the ablation rate and improve dimensional stability of composites used in thermal protection systems. The mesophase-pitch-based carbon fibers/pyrocarbon skeleton is designed as the thermal diffusion channel using the intermediate state mesophase-pitch-based carbon fibers and chemical vapor infiltration method. After successive graphitization and polymer precursor impregnation and pyrolysis, the obtained ZrC–SiC-modified carbon/carbon composite exhibits a high thermal conductivity of 206.5 W m−1 K−1 in the X(Y) direction. The ablation results indicate that the composite exhibits a surface temperature of 241 °C, which is lower than that of the composite without mesophase-pitch-based carbon fibers, thus verifying the improved ablation resistance. The linear and mass ablation rates of the composite are found to be 0.33 μm s−1 and 0.56 mg cm−2 s−1, respectively. The thermal conduction mechanism of the ZrC–SiC-modified carbon/carbon composite near the ablation center is investigated to show the combined phonon heat conduction and thermal radiation. This study provides a protocol for the design and construction of modified carbon/carbon composites having high thermal conductivity for application in hypersonic vehicles.

The aim of this work is to investigate the effect of moisture on the measured tensile strength of polyacrylonitrile (PAN) carbon fibers immersed in epoxy matrix under various moisture conditions. Tensile tests are carried out for the specimens, and a sharp decrease in measured tensile strength of the carbon fibers/epoxy system A immersed under high-moisture conditions is observed. Scanning electron microscope (SEM) is used to observe the effect of moisture on the surface structures of specimens. The results show that the decrease in the measured tensile strength is attributed to the microvoids of epoxy matrix formed in the preparation of the specimens. And the formation of microvoids in carbon fiber/epoxy matrix depends on viscosity change and curing condition of epoxy system. During the early stage of epoxy curing, both the solvent and absorbed water in the epoxy system escape from the immersed carbon fibers and form channels in the epoxy matrix. Once the viscosity of the epoxy system increased rapidly at a low curing temperature, the channels cannot be filled quickly by the surrounding resin and form microvoids finally. In order to verify these results, epoxy system B with a high curing temperature is chosen to prepare the specimens for tensile tests, and SEM images demonstrate that there are no microvoids that can be observed on the surfaces of specimens, even at such a high-moisture condition. And the measured tensile strengths remain unaffected in both low and high-moisture conditions. These results indicate that epoxy system with a high curing temperature is suitable for preparing the specimens for tensile tests regardless of moisture condition in the surrounding air.

Purpose – The purpose of this paper is a study aimed at overcoming the interface issue between nanopaper and polymer matrix in shape-memory polymer (SMP) composite laminates caused by their large dissimilarity in electrical/thermal conductive properties. The study attempted to develop an effective approach to fabricate free-standing carbon nanofibre (CNF) assembly in octagon shape formation. The structure design and thermal conductive performance of the resulting octagon-shaped CNF assembly were optimised and simulated. Design/methodology/approach – The CNF nanopaper was prepared based on a filtration method. The SMP nanocomposites were fabricated by incorporating these CNF assemblies with epoxy-based SMP resin by a resin-transfer modelling technique. Thermal conductivity of the octagon-shaped CNF assembly was simulated using the ANSYS FLUENT software for structure design and optimisation. The effect of the octagon-shaped CNF on the thermomechanical properties and thermally responsive shape-memory effect of the resulting SMP nanocomposites were characterised and interpreted. Findings – The CNF template incorporated with SMP to achieve Joule heating triggered shape recovery at a low electric voltage of 3-10 V, due to which the electrical resistivity of SMP nanocomposites was significantly improved and lowered to 0.20 O·cm by the CNF template. It was found that the octagon CNF template with 2 mm width of skeleton presented a highest thermally conductive performance to transfer resistive heat to the SMP matrix. Research limitations/implications – A simple way for fabricating electro-activated SMP nanocomposites has been developed by using an octagon CNF template. Low electrical voltage actuation in SMP has been achieved. Originality/value – The fabricated CNF template, the structure design and analysis of dynamic thermomechanical properties of SMP are novel.