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Rapid urbanization has made road construction and maintenance imperative, but detecting road diseases has been time-consuming with limited accuracy. To overcome these challenges, we propose an efficient YOLOv7 road disease detection model. Our approach involves integrating MobilieNetV3 as the backbone feature extraction network to reduce the network's parameters and computational requirements. Additionally, we introduce the BRA attention module into the spatial pyramid pooling module to eliminate redundant information and enhance the network's feature representation capability. Moreover, we utilize the F-ReLU activation function in the backbone network, expanding the convolutional layers' receptive field range. To optimize the model's boundary loss, we employ the Wise-IoU loss function, which places more emphasis on the quality of ordinary samples and enhances the overall performance and generalization ability of the network. Experimental results demonstrate that our improved detection algorithm achieves a higher recall rate and mean average precision (mAP) on the public dataset (RDD) and the NJdata dataset in Nanjing's urban area. Specifically, compared to YOLOv7, our model increases the recall rate and mAP on RDD by 3.3% and 2.6%, respectively. On the NJdata dataset, our model improves the recall rate and mAP by 1.9% and 1.3%, respectively. Furthermore, our model reduces parameter and computational requirements by 30% and 22.5%, respectively, striking a balance between detection accuracy and speed. In conclusion, our road disease detection model presents an effective solution to address the challenges associated with road disease detection in urban areas. It offers improved accuracy, efficiency, and generalization capabilities compared to existing models. [ABSTRACT FROM AUTHOR]

Rationally adjusting the interface between SnO2 electron transport layer (ETL) and the perovskite (PVK) buried surface plays a key role in achieving efficient and stable PVK solar cells (PSCs). Herein, a cost‐effective organic salt, 5‐bromo‐6‐chloro‐3‐indolyl sulfate potassium salt (SPS), used as an interface modifier is deposited on the SnO2 ETL. SPS has played a multifunctional role in ETL and PVK layer: 1) the highly electronegative SO4− group of SPS can be adsorbed on the surface of SnO2 films, resulting in the energy levels of the PVK layer and SnO2 ETL becomes more compatible. 2) The lower contact angle of the modified SnO2 film is conducive to the formation of pinhole‐free PVK films. 3) The functional groups in SPS are helpful for the decrease of defect density in the PVK films. As a consequence, the defect density reduces from 8.17 × 1015 to 5.57 × 1015 cm−3. The power conversion efficiency (PCE) of modified PSCs increases from 19.82% to 21.33%. Furthermore, the unencapsulated modified devices retain 91.7% of the initial PCE after 624 h. These results indicate that using SPS as a multifunctional interface modifier is a promising strategy to achieve efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

The sliding electrical contact (SEC) between rails and armature is a focus in electromagnetic rail launchers. The extreme conditions, such as high current density, high temperature, and high contact pressure, influence SEC performance. In this article, the segmented rails were used to study the effects of launch mass on SEC. Two groups of experiments, armatures with and without launch mass, were carried out. The mass difference of rail parts was measured, the macro- and micromorphology of rails surface were observed, and the driving current and muzzle voltage were obtained. Three conclusions are obtained: 1) the mass difference of rail parts in shooting with launch mass is greater than that without launch mass, due to the high temperature of armature contact surfaces; 2) because of the electron migration, the mass difference of the cathode rail is larger than the anode rail; and 3) the contact resistance between rails and armature without launch mass is lower than that with launch mass, result from the large contact area. Moreover, the current density and the temperature of the armature and rails were calculated. Results show that the temperature of surface of armature with launch mass is higher than that without launch mass. In a word, based on the results from experiments and simulations, the launch mass improves the sliding electric contact performance. [ABSTRACT FROM AUTHOR]

The [Ca24Al28O64]4+:4e− (C12A7:e−) electride is a conductive oxide ceramic with high injected electron concentration and low work function, but its brittleness leads to difficulty in mechanical processing and low production yield. The present work aimed at improving the mechanical properties of C12A7:e− by introducing monoclinic ZrO2. When the ZrO2 content was 5 wt%, the fracture toughness increased 133% from 1.819 to 4.214 MPa m1/2 and the flexural strength increased 116% from 15.916 to 34.469 MPa for C12A7:e−-5 wt% ZrO2, indicating that ZrO2 can effectively improve the mechanical properties of C12A7:e−. The microstructure and phase analysis showed that the toughening mechanisms of ZrO2 composite C12A7:e− contain both stress-induced phase transformation toughening and dispersion toughening of ZrO2 particles. When the content of ZrO2 is between 0 and 5 wt%, the injected electron concentration of C12A7:e−-ZrO2 was maintained in the range of 2.05–2.10 × 1021 cm−3 and illustrate excellent electrical transport properties. The study indicated that adding ZrO2 in C12A7:e− effectively solves the problem of brittle fracture, improves the finished product rate during processing, and maintains its excellent electrical transport properties. [ABSTRACT FROM AUTHOR]

Armature ejecta, which erodes the insulator and reduces surface dielectric strength, has been considered as a threat to solid-armature launchers. Two series of experiments were carried out in a small caliber launcher (SCL) to investigate the sources of armature ejecta and degradation mechanisms of the insulator. In first series of experiment, the ejection of armature was imaged by a high-speed camera. The influence of linear current density on ejection was studied in second series of experiment. Mass difference of insulator samples was used to evaluate the output of armature ejecta. Insulation performance was judged from the surface flashover voltage. And the degradation mechanism resulted from armature ejecta was analyzed based on the process of surface flashover. Results show that the local breakdown at armature–rail interfaces is one of the sources of armature ejecta. The amount of ejecta on samples increased with linear current density. Average flashover voltages decreased when ejecta increased in Zone A (0–200 mm) and Zone B (200–600 mm). And there was little difference of average flashover voltages in Zone C (600–900 mm). The discharge channel of the post-shot sample was composed of arcs and ejecta. The distortion of the surface electric field and the shorten of creepage distance are degradation mechanisms of bore insulators in solid-armature launchers. [ABSTRACT FROM AUTHOR]

Muzzle arc is a general phenomenon when the armature leaves the muzzle, and it is also a reason for the complexity of intermediate ballistic of electromagnetic launchers. In this article, a 3-D model has been developed to investigate muzzle arc flow field in a smaller caliber launcher. The coupled interaction of electromagnetic, flow, and thermal fields is realized by the magnetohydrodynamic (MHD) theory in conjunction with a renormalization group (RNG) $k$ - $\varepsilon $ turbulence model. The arc boundary conditions, arc root radius, and time-dependent current density are reasonably set on the basis of the experimental data and physical process. Simulation results reveal the relationship between muzzle arc and muzzle voltage. The rising edge of muzzle voltage corresponds to the arc expansion stage. The falling edge corresponds to the muzzle breakdown stage. And the turning point from rising edge to falling edge is the moment of muzzle breakdown. The flat section corresponds to the arc extinguishing stage. The muzzle blowback is the consequence of the arc expansion which produces a compression wave moving toward the breech. The velocity of blowback flow decreases from 670 to 270 m/s during the arc expansion stage. Then, it increases to about 350 m/s and tends to be stable due to the muzzle breakdown. [ABSTRACT FROM AUTHOR]

For reconstructive surgeons, critically skeletal damage represents a major challenge. Growing evidence indicate that bone repair is dynamically regulated by the mesenchymal stem cell (MSC)‐macrophage interaction. Mechanical strain plays a fundamental role in bone repair and regeneration by influencing MSCs differentiation. Recently, a few findings indicate that macrophages may be mechanically sensitive and their phenotype can be regulated, in part, by mechanical cues. However, how macrophages subjected mechanical stretch influence the osteogenic differentiation of MSCs remain unclear. Thus, the purpose of this study is to explore the effect of macrophages stimulated with mechanical stretch on MSCs osteogenesis. By using a coculture system, we discover that macrophages efficiently induce osteogenic differentiation of MSCs under specific stretch conditions. A synergy mechanism between M2 polarization and YAP/BMP2 axis are identified through molecular and genetic analyses. Macrophages are activated by cyclic stretch and polarized to M2 phenotype that produce anti‐inflammatory cytokines such as IL‐10 and TGF‐β to regulate the local inflammatory microenvironment. Furthermore, mechanical stretch induces YAP activation and nuclear translocation, subsequently regulates downstream BMP2 expression to facilitate MSCs osteogenesis. These findings not only advance our understanding of the complex influence among the mechanical strain, macrophage inflammatory response as well as the osteogenic differentiation of MSCs, but also reveal a control system from mechanical signals to chemical response then to cell behaviors during bone repair and regeneration. [ABSTRACT FROM AUTHOR]