A Review of Dynamic Object Filtering in SLAM Based on 3D LiDAR.

SLAM (Simultaneous Localization and Mapping) based on 3D LiDAR (Laser Detection and Ranging) is an expanding field of research with numerous applications in the areas of autonomous driving, mobile robotics, and UAVs (Unmanned Aerial Vehicles). However, in most real-world scenarios, dynamic objects can negatively impact the accuracy and robustness of SLAM. In recent years, the challenge of achieving optimal SLAM performance in dynamic environments has led to the emergence of various research efforts, but there has been relatively little relevant review. This work delves into the development process and current state of SLAM based on 3D LiDAR in dynamic environments. After analyzing the necessity and importance of filtering dynamic objects in SLAM, this paper is developed from two dimensions. At the solution-oriented level, mainstream methods of filtering dynamic targets in 3D point cloud are introduced in detail, such as the ray-tracing-based approach, the visibility-based approach, the segmentation-based approach, and others. Then, at the problem-oriented level, this paper classifies dynamic objects and summarizes the corresponding processing strategies for different categories in the SLAM framework, such as online real-time filtering, post-processing after the mapping, and Long-term SLAM. Finally, the development trends and research directions of dynamic object filtering in SLAM based on 3D LiDAR are discussed and predicted.

Mechanistic Insights into the Intercalation and Interfacial Chemistry of Mesocarbon Microbeads Anode for Potassium Ion Batteries.

Mesocarbon microbeads (MCMB) are highly desirable as anode materials for rechargeable potassium ion batteries (PIBs) due to their commercially availability, high stability and low-cost. However, their charge storage and interfacial mechanisms are still unclear. In this work, the intercalation mechanisms and the solid-electrolyte-interphase (SEI) formation of the MCMB in four different electrolytes is comprehensively studied. The MCMB anodes exhibit superior rate and cycle performances via a naked K-ions sequentially staging intercalation mechanism, realizing the complete transformation from graphite to KC8 . Whereas a solvated K-ions co-intercalation mechanism of the MCMB occurs in ether-based electrolytes, which might induce graphite exfoliation and result in unsatisfied specific capacity and capacity decay. Nevertheless, this co-intercalation behavior could be effectively suppressed by a highly concentrated electrolytes. Interfacial analyses unveil the distinct SEI components, which vary with the electrolyte chemistries. These SEI components also varies from surface to bulk and especially attention should be paid to the accurate control of the concentration of the fluoroethylene carbonate additives. This work provides a panoramic understanding of the intercalation and interfacial mechanisms on the MCMB anodes for PIBs.

Nitrogen- and Oxygen-Containing Three-Dimensional Hierarchical Porous Graphitic Carbon for Advanced Supercapacitor.

Three-dimensional hierarchical porous graphitic carbon (HPGC) were synthesized via one-step carbonization-activation and a catalytic strategy. The method can not only improve the graphitization degree of carbon materials, but also offer plentiful interfaces for charge accumulation and short paths for ion/electron transport. Polypyrrole, potassium hydroxide, and nickel acetate were used as the carbon precursors, activating agent, and catalyst, respectively. The retraction and dissolution of Ni caused the change of pore size in the material and led to the interconnected micro/nano holes. Nickel acetate played a significant role in enhancing the electrical conductivity, introducing pseudocapacitance, and promoting ion diffusion. In the supercapacitor, HPGC electrode exhibited a remarkable specific capacitance of 336.3 F g-1 under 0.5 A g-1 current density and showed high rate capability, even with large current densities applied (up to 50 A g-1). Moreover, HPGC showed optimal cycling stability with 97.4% capacitance retention followed by 3000 charge-discharge cycles. The excellent electrochemical performances coupled with a facile large-scale synthesis procedure make HPGC a promising alternative for supercapacitors.

Encapsulation of Few-Layer MoS2 in the Pores of Mesoporous Carbon Hollow Spheres for Lithium-Sulfur Batteries.

Integrating a highly conductive carbon host and polar inorganic compounds has been widely reported to improve the electrochemical performances for promising low-cost lithium sulfur batteries. Herein, a MoS2/mesoporous carbon hollow sphere (MoS2/MCHS) structure has been proposed as an efficient sulfur cathode via a simple wet impregnation method and gas phase vulcanization method. Multi-fold structural merits have been demonstrated for the MoS2/MCHS structures. On one hand, the mesoporous carbon hollow sphere (MCHS) matrix, with abundant pore structures and high specific surface areas, could load a large amount of sulfur, improve the electronical conductivity of sulfur electrodes, and suppress the volume changes during the repeated sulfur conversion processes. On the other hand, ultrathin multi-layer MoS2 nanosheets are revealed to be uniformly distributed in the mesoporous carbon hollow spheres, enhancing the physical adsorption and chemical entrapment functionalities towards the soluble polysulfide species. Having benefited from these structural advantages, the sulfur-impregnated MoS2/MCHS cathode presents remarkably improved electrochemical performances in terms of lower voltage polarization, higher reversible capacity (1094.3 mAh g-1), higher rate capability (590.2 mAh g-1 at 2 C), and better cycling stability (556 mAh g-1 after 400 cycles at 2 C) compared to the sulfur-impregnated MCHS cathode. This work offers a novel delicate design strategy for functional materials to achieve high performance lithium sulfur batteries.

Novel Mesoporous Flowerlike Iron Sulfide Hierarchitectures: Facile Synthesis and Fast Lithium Storage Capability.

The 3D flowerlike iron sulfide (F-FeS) is successfully synthesized via a facile one-step sulfurization process, and the electrochemical properties as anode materials for lithium ion batteries (LIBs) are investigated. Compared with bulk iron sulfide, we find that the unique structural features, overall flowerlike structure, composed of several dozen nanopetals and numerous small size iron sulfide particles embedded within the fine nanopetals, and hierarchical pore structure features provide signification improvements in lithium storage performance, with a high-rate discharge capacity of 779.0 mAh g-1 at a rate of 5 A g-1, due to effectively alleviating the volume expansion during the lithiation/delithiation process, and shorting the diffusion length of both lithium ion and electron. Especially, an excellent cycling stability are achieved, a high discharge capacity of 890 mAh g-1 retained at a rate of 1.0 A g-1, suggesting its promising applications in lithium ion batteries (LIBs).

Synthesis of poly(anilineboronic acid) nanofibers for electrochemical detection of glucose.

Poly(anilineboronic acid) (PABA) nanofibers with U-shaped and ring-shaped morphologies have been synthesized successfully by chemical polymerization of 3-aminophenylboronic acid (APBA) in the presence of cetyltrimethylammonium bromide (CTAB) and NaF. The morphologies and sizes of PABA nanofibers can be controlled by adjusting the synthetic parameters, such as the concentrations of CTAB and APBA. The U-shaped PABA nanofibers exhibit excellent electrochemical redox activity and high sensitive detection of D-glucose in phosphate-buffered saline stock solution (pH 7.4) because of their high effective surface area as well as the high density of boronic acid groups.

Synthesis of urchin-like VO2 nanostructures composed of radially aligned nanobelts and their disassembly.

Urchin-like VO(2)(B) nanostructures composed of radially aligned nanobelts have been synthesized by the homogeneous reduction reaction between peroxovanadic acid and oxalic acid under hydrothermal conditions. The influences of synthetic parameters, such as reaction times and the concentration of oxalic acid, on the morphologies and crystals of the resulting products have been investigated. The formation of VO(2)(B) nanostructures undergoes a reduction-dehydration phase-transition and disassembly process. As the reaction time increases from 2 to 6 h, the diameters of urchin-like V(10)O(24) x 12 H(2)O nanostructures increase from 1-2 microm to 3-6 microm. After 12 h, urchin-like V(10)O(24) x 12 H(2)O nanostructures can be transformed in situ into VO(2)(B) nanostructures composed of radially aligned nanobelts, which can be described by a possible reduction-dehydration phase-transition process. The urchin-like VO(2)(B) nanostructures are disassembled into dissociated VO(2)(B) nanobelts with the reaction time increased to 24 h. The shapes of the dissociated VO(2)(B) nanobelts can be controlled by adjusting the concentration of oxalic acid.

One-Dimensional V(2) O(5) @Polyaniline Core/Shell Nanobelts Synthesized by an In situ Polymerization Method.

Uniform one-dimensional V(2) O(5) @polyaniline core/shell nanobelts have been fabricated by a simple in-situ polymerization method in the absence of any surfactant and additional initiator. The influences of pH and additional initiator on the morphology of the resulting products are investigated. The pH value is important for the formation of V(2) O(5) @polyaniline core/shell nanobelts, which preserve the original morphology of V(2) O(5) nanobelts. With a decrease in the pH value to 0 the original morphology of the V(2) O(5) nanobelts is destroyed. When ammonium peroxydisulfate is used, some separated polyaniline nanofibers are formed. The formation of the V(2) O(5) @polyaniline core/shell nanobelts can be related to the in-situ polymerization of aniline monomer by etching V(2) O(5) nanobelts. The electrochemical lithium intercalation/deintercalation of V(2) O(5) @polyaniline core/shell nanobelts is investigated by cyclic voltammograms.

Low-valent vanadium oxide nanostructures with controlled crystal structures and morphologies.

Low-valent vanadium oxide nanostructures have been synthesized in large quantities using commercial V2O5 powder as the precursor by a facile reduction method. The crystal structures and morphologies of vanadium oxide nanostructures can be adjusted by altering the concentrations and types of reductants. VO2(B) nanostructures are fabricated using oxalic acid as the reductant. VO2(B) nanobelts with widths of 80-150 nm, thicknesses of 20-30 nm, and lengths up to several micrometers can evolve to olive-like nanostructures composed of nanosheets with thicknesses of several nanometers and lateral dimensions of several micrometers as the concentration of oxalic acid increases. H2V3O8 nanobelts with widths of 200-300 nm, thicknesses of 10-20 nm, and lengths up to several 10s of micrometers are obtained under the reduction of V2O5 powder with ethanol. The belt-shaped morphologies of H2V3O8 are not affected by the concentration of ethanol.

Molybdenum trioxide nanostructures: the evolution from helical nanosheets to crosslike nanoflowers to nanobelts.

MoO(3) nanostructures with different morphologies, such as helical nanosheets, crosslike nanoflowers, and nanobelts, have been synthesized on a large scale by an environmentally friendly chemical route. The evolution process from helical nanosheets to crosslike nanoflowers to nanobelts is observed for the first time. The influences of reaction time and the molar ratio of molybdenum and H(2)O(2) on the morphologies of MoO(3) nanostructures have been investigated. The synthetic process is environmentally friendly and may be extended to synthesize nanostructures of other metal (W, Ti, and Cr) oxides.