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With the significant increase in demand for artificial intelligence, environmental map reconstruction has become a research hotspot for obstacle avoidance navigation, unmanned operations, and virtual reality. The quality of the map plays a vital role in positioning, path planning, and obstacle avoidance. This review starts with the development of SLAM (Simultaneous Localization and Mapping) and proceeds to a review of V-SLAM (Visual-SLAM) from its proposal to the present, with a summary of its historical milestones. In this context, the five parts of the classic V-SLAM framework—visual sensor, visual odometer, backend optimization, loop detection, and mapping—are explained separately. Meanwhile, the details of the latest methods are shown; VI-SLAM (Visual inertial SLAM) is reviewed and extended. The four critical techniques of V-SLAM and its technical difficulties are summarized as feature detection and matching, selection of keyframes, uncertainty technology, and expression of maps. Finally, the development direction and needs of the V-SLAM field are proposed.

In this paper, a land use management information system based on ArcGIS 3D modeling technology is constructed to process land use policy decisions through ArcSDE spatial data engine and Oracle relational database to realize a land use planning management information system. Using genetic algorithm in order to use for regional land use optimization allocation, the introduction of multi-intelligent body system in this algorithm will be able to enhance the optimization search ability of the algorithm and make the genetic algorithm to obtain land use planning supported. The behavior of the main body of the integrated land use planning decision maker will guide the development of the quantitative structure of land use in terms of spatial layout toward sustainability. The experimental results prove that the target is better than the other three types of scenarios under the integrated benefit model, then it is reduced by 18.67%, 15.98% and 16.61%, and the number of spatially contiguous areas is increased by 9.4%, 13.8% and 0.8%, respectively. The proposed model can reasonably configure the regional land use quantitative results and spatial layout, and coordinate the needs of different land use decision makers.

Deep-blue perovskite light-emitting diodes (PeLEDs) based on reduced-dimensional perovskites (RDPs) still face a few challenges including severe trap-assisted nonradiative recombination, sluggish exciton transfer, and undesirable bathochromic shift of the electroluminescence spectra, impeding the realization of high-performance PeLEDs. Herein, an in situ chlorination (isCl) post-treatment strategy was employed to regulate phase reconstruction and renovate multiple defects of RDPs, leading to superior carrier cooling of 0.88 ps, extraordinary exciton binding energy of 122.53 meV, and higher photoluminescence quantum yield of 60.9% for RDP films with deep-blue emission at 450 nm. The phase regulation is accomplished via fluorine-derived hydrogen bonds that suppress the formation of small- n phases. Multiple defects, including halide vacancies (shallow-state defects) and lead-chloride antisite defects (deep-state defects), are renovated via C=O coordination and hydroxy-group-derived hydrogen bonds. Consequently, deep-blue PeLEDs with a record maximum external quantum efficiency of 6.17% and stable electroluminescence at 454 nm were demonstrated, representing the best-performing deep-blue PeLEDs. In situ chlorination strategy was proposed to renovate multiple defects along with reconstruction of phases in RDPs for efficient and spectrally stable deep-blue PeLEDs with a record EQE of 6.17%.

As a vital ecological barrier and water source for the Beijing-Tianjin-Hebei (BTH) region, the Luan River Basin (LRB) plays a crucial role in maintaining regional ecological balance. However, comprehensive research on Ecological Vulnerability (EV) evaluation in the LRB remains scarce, making EV evaluation and forecasting particularly significant. This study evaluated EV dynamics (2002–2022) via the SRP model with 17 indicators, with driving factors analyzed via Geodetector and 2032 scenarios forecasted by CA-Markov. Key findings revealed: (1) EVI increased from 0.397 to 0.428 (peak at 0.445 in 2017), with Microscopic vulnerability dominating (46.47% average area). (2) Spatially, EV exhibited a “low-medium–high” gradient (lower in northwestern high-altitude areas and higher in southeastern plains), confirmed by significant clustering (Global Moran’s I = 0.889–0.938, p value < 0.001). (3) Geodetector identified elevation (q = 0.855), biological abundance (q = 0.812), annual temperature (q = 0.800), and cultivated land proportion (q = 0.783) as primary driving factors. (4) CA-Markov forecasts for 2032 indicate declines in Potential vulnerability (− 5.83%), Microscopic vulnerability (− 2.01%), and Severe vulnerability (− 2.30%), but increases in Mild vulnerability (+ 6.57%) and Moderate vulnerability (+ 3.57%). These findings provide a scientific basis for evidence-based ecological policies in the LRB, contributing to the promotion of regional sustainable development and the balance between ecological conservation and economic growth.

The millet collision coefficient of restitution (COR) is one of the important elementary physical parameters for researching the precision hole seeding system. In this study, to explore the factors affecting the bounce issue observed when seeds exit the seed-metering and seed-guiding devices, the dynamic equations for the millet collision process were derived employing Newtonian kinematics, and a COR measurement test bench was built. The effects of collision material type, speed and variety respectively on the COR were investigated by single-factor experiments and orthogonal experiments. Single-factor tests revealed that COR values decreased in the sequence of Acrylic plate, ABS, Rubber, Black soil,Meadow soil, and Sandy loam soil, with Tuogu exhibiting higher COR than Zhang Zagu 13 and Shuangyu, the latter having the lowest value. During two collision phases, the COR progressively decreased as seeding speed increased. Orthogonal tests identified the significant influences of each factor. A combination of bench and simulation tests validated the test results, showing no significant differences and confirming the method’s viability for determining COR. These findings offer a reference for optimizing the design of relevant components within the millet metering system.

The geological sequestration of CO2, underground coal mining, and coalbed methane production in deep coal reservoirs is executed under high levels of 3-D geo-stress, and it is accompanied by significant variations in both vertical and horizontal stresses. In addition, coal is a highly fractured porous medium characterized by complex natural fracture systems. This exterior and interior anisotropy complicates the replication of in situ conditions in the laboratory. In this study, we divided pre-existing fracture systems of cubic coal into three flow planes: a bedding plane, face cleat plane, and butt cleat plane. Gas flowed through cubic coal samples along each flow plane under differently designed true triaxial stress paths. We then further analyzed anisotropic mechanical and flow property responses of cubic coal after failure by model fitting, CT scan reconstruction, and fractal representation. The experimental results indicate that pre-existing flow planes play significant roles in the strength levels, failure modes, and permeability levels. Low strength levels, typical shear failure patterns, and low initial permeability levels were observed in the butt cleat plane direction. Anisotropic strength data can be effectively fit by applying a linear relationship between octahedral shear stress and mean effective normal stress. After coal failure, the peak permeability observed in the face and butt cleat plane directions also presents a strong linear relationship with the fractal dimension. An anisotropic conceptual failure process model was established for the description of internal fracture development during stress loading. Horizontal stress unloading decreased the strength and formed a more complex fracture system in cubic coal regardless of the different flow planes involved, producing the increments of associated peak permeability.

The waterless fracturing method with liquid nitrogen (LN2) as the fracturing fluid has been proposed and successfully applied in coalbed methane (CBM) production in recent years. The temperature of the coal reservoir sharply decreases, causing damage to the pore structure of the coal reservoir due to the ultralow temperature of LN2 during fracturing. Thus, in this paper, infrared thermal imaging (ITI) and nuclear magnetic resonance (NMR) were used to measure the temperature distribution and pore evolution law of anthracite coal. The results demonstrate that the temperature of the coal sample after being frozen by LN2 was far less than 0°C, which causes the internal water of the coal sample to freeze and turn into ice and produce a frost‐heave force. In addition, the temperature of the coal samples was not fixed but fluctuated, which led to the formation of a temperature gradient and induced thermal stress. The T2 spectra variation showed that LN2 freeze‐thaw cycles can promote the development of pores in coal samples and enhance the connectivity of pores. Some of the micropores gradually connect and expand to form a large number of mesopores and macropores under the influence of frost‐heave force and thermal stress. The total porosity, residual porosity, and effective porosity increase with the number of LN2 freeze‐thaw cycles. The NMR imaging directly reflects the change characteristics of the internal pore structure before and after LN2 freeze‐thaw, which provide a new way to reveal the pore evolution law of anthracite. These results show that LN2 freeze‐thaw cycles can damage the pore structure of anthracite coal, and a large number of mesopores and macropores are formed to provide channels for CBM migration, which improves the efficiency of LN2 fracturing. The pore evolution law of anthracite coa under liquid nitrogen freeze‐thaw cycles.

Wireless Underground Sensor Networks (WUSNs), an important part of Internet of things (IoT), have many promising applications in various scenarios. Signal transmission in natural soil undergoes path loss due to absorption, radiation, reflection and scattering. The variability and dynamic of soil conditions and complexity of signal attenuation behavior make the accurate estimation of signal path loss challenging. Two existing propagation models for predicting path loss are reviewed and compared. Friis model does not consider the reflection loss and is only applicable in the far field region. The Fresnel model, only applicable in the near field region, has not considered the radiating loss and wavelength change loss. A new two stage model is proposed based on the field characteristics of antenna and considers four sources of path loss. The two stage model has a different coefficient m in the near field and far field regions. The far field distance of small size antenna is determined by three criteria: 2 D2/λ, 5 D, 1.6 λ in the proposed model. The proposed two stage model has a better agreement with the field experiment data compared to Friis and Fresnel models. The coefficient m is dependent on the soil types for the proposed model in near field region. It is observed from experiment data that the m value is in the range of 0~0.20 for sandy soils and 0.433~0.837 for clayey silt.

With the increase of coal extracting depth, a considerable number of dynamic disasters display the co-occurrence and coupling effect of rockburst and coal–gas outburst, which is defined as the disturbed compound dynamic disaster. In this study, two loading modes were adopted to investigate disaster characteristics using true triaxial apparatus. The stress states of one freed and the other five stressed faces were introduced to simulate actual stress conditions. Two high-speed cameras were used to capture the disaster process. The mechanical and strength properties, failure modes, and ejection kinetic energy were analyzed. Results showed that the compound dynamic disaster mainly exhibited local grain ejection, fragment spalling, large-scale grain ejection, plate bending, and ultimately failure. The strength of the sample first increased and then decreased slowly with the increase in the intermediate principal stress. After failure, a V-shaped coal-burst pit was formed, which was approximately parallel to the intermediate principal stress and perpendicular to the free face. The grain ejection exhibited obvious characteristics of spatial sorting, and the grain size decreased with the distance from the free face. The kinetic energy showed little change with increase in the intermediate principal stress in the displacement loading mode; whereas, it first increased and then decreased in the stress loading mode. The pressurized gas promotes the development of coal cracks and fully fractures the coal rock. Under the combined actions of the elastic energy stored in coal mass and the internal energy of pressurized gas, compound dynamic disasters may occur. Gas extraction and coal seam elastic softening techniques can effectively reduce and prevent the occurrence probability of compound dynamic disasters.

In underground coal mining, coal failure generally occurs due to the relatively weak strength of the coal and the high applied mining-induced stresses. The outer complex geological conditions (i.e., tectonic structure and water intrusion) and internal structural anisotropy of the coal introduce uncertainty in predicting its mechanical properties and failure behavior. In this study, laboratory investigations of the mechanical properties and failure behavior of dry and water-saturated anisotropic coal samples subjected to different true-triaxial loading stresses were conducted. The effects of water weakening, intermediate stress, and structural anisotropy on the mechanical properties and failure behavior of the coal were systematically studied. The results indicate that the presence of water significantly reduced the strength, elastic modulus, and strength anisotropy of the coal. The maximum stress at failure first increased and then decreased with increasing intermediate stress. The residual strength-to-peak strength ratios and failure plane angles of the coal showed a linear increase with increasing intermediate stress. When the coal samples were loaded in the bedding plane direction, the brittleness of the coal was higher than when they were loaded in the other two cleat plane directions. In addition, when the coal samples were loaded in the butt cleat plane direction, the brittleness of the coal decreased with increasing intermediate stress. Two typical failure modes of the dry and water-saturated coal samples were observed: shear and mixed splitting and shear failures. The dominant failure mode of the coal also varied with the loading direction relative to the weakness planes, which could be well recognized and predicted by the acoustic emission (AE) characteristic curves. To further reveal the fracture mechanism, the microcrack patterns of the coal were further identified based on the AE parameters.