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Adaptability to unstructured objects and the avoidance of target damage are critical challenges for flexible grippers in fruit-picking robots. Most existing flexible grippers have many problems in terms of control complexity, stability and cost. This paper proposes a flexible finger design method that considers contact behavior. The new approach incorporates topological design of contact targets and introduces contact stress constraints to directly obtain a flexible finger structure with low contact stress and good adaptability. The study explores the effects of design parameters, including virtual spring stiffness, volume fraction, design domain size, and discretization, on the outcomes of the flexible finger topology optimization. Two flexible finger structures were selected for comparative analysis. The experimental results verified the effectiveness of the design method and the maximum contact stress was reduced by about 70%. An adaptive two-finger gripper was developed. This design allows the gripper to achieve damage-free grasping without additional sensors and control systems. The adaptive and contact performances of the grippers with different driving modes were analyzed. Practical grasping tests were also performed, including evaluation of adaptive performance, stability, and maximum grasping weight. The results indicate that gripper 2 with flexible finger 2 excelled in contact stress and adaptive wrapping, making it well-suited for grasping unstructured and fragile objects. This paper provides valuable insights for the design and application of flexible grippers for picking robots, offering a promising solution to enhance adaptability while minimizing target damage. [ABSTRACT FROM AUTHOR]

In this Letter, we present a multistage smart radiator with a gradient emittance that gradually increases with increasing temperature in the spectral range of 2.5–15 μm. Such smart radiator is a relatively simple multilayered structure composed of three phase change materials (PCMs): VO2, GST, and IST. The smart radiator achieves multistage manipulation of emittance through phase transitions of PCMs, with the largest emittance tunability of ∼0.85. The underlying mechanism involves manipulating the Fabry–Pérot resonance and antireflection. Additionally, the emittance is found to be relatively insensitive to polarization and incident angles. The proposed multistage smart radiator exposes excellent potential for exploitation in thermal management and energy conservation. [ABSTRACT FROM AUTHOR]

The rapid development of the Internet of Things increases the demand for wearable devices. Compared with traditional chemical batteries, flexible thermoelectric technology contributes a solution for solving the power supply of wearable electronics. Here, we prepared n-type Bi2Te3 and p-type Bi0.5Sb1.5Te3 flexible thermoelectric films by the magnetron sputtering method, where the thermoelectric performance and their microstructures are systematically studied. The carrier concentration and mobility are optimized by adjusting the deposition temperature, eventually improving the thermoelectric performance and achieving the room-temperature power factors of 3.2 and 6.1 μW cm−1 K−2 for Bi2Te3 and Bi0.5Sb1.5Te3 films, respectively. Furthermore, after being bent 900 times with a radius of 5 mm, the resistance of these films barely increases, demonstrating the great potential for applications in wearable electronics. In order to further evaluate the practicability, these films are used to design a flexible thermoelectric generator, in which output performance improves with the increase in the temperature difference. The power density is up to ∼218.8 μW cm−2 at temperature differences of ∼41 K. [ABSTRACT FROM AUTHOR]

Background: Pesticide spraying constitutes an essential component of the production and management regimen within banana orchards, extending throughout the entire growth cycle of the banana plants. Exploring the intricate interplay between surfactants, pesticide formulations, and the evolving surface properties of banana leaves throughout their growth stages is critical to the enhancement of pesticide application methods and the elevation of agricultural productivity., Results: Through investigating the regulatory impact of surfactants on the physicochemical properties of medicinal solutions, this study elucidates the interaction mechanism between the physicochemical properties of pesticides and the surface characteristics of banana leaves. The findings reveal that the energy dissipation rate of pesticide droplets exhibits a natural exponential rise in correlation with the increase in both the We number and the concentration of surfactant present. Comparatively, the adaxial surface of banana leaves demonstrates superior spreading and adhesion properties for droplets than the abaxial surface. Specifically, droplets containing the anionic surfactant sodium dodecyl sulfate on the adaxial surface of banana leaves are found to spread well with a reduced retraction effect. Conversely, the application of the non-ionic surfactant fatty acid polyoxyethylene ether (AEO-3) on the abaxial surface of banana leaves is more beneficial for the wetting and retention of droplets. As banana leaves grow, there is a noted decline in the spreading and retraction properties of droplets. However, droplets have a higher propensity to wet and adhere to the surfaces of mature banana leaves., Conclusion: To bolster the adherence of pesticide droplets to leaf surfaces, it is imperative to ensure they possess superior spreading properties and a controlled retraction pace. This facilitates an extended period of contact and enhanced stability, thereby optimizing the spray's deposition efficacy. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

A microalgal cell model with multiple organelles considering both the irregular overall shape and internal microstructure was proposed. The radiative properties of Parachlorella kessleri during the normal phase, starch-rich phase, and lipid-rich phase were calculated by the discrete dipole approximation method in the visible wavelengths. The accuracy of the model is verified with experimental measurements. The results showed that the theoretical calculation of the established microalgal cell model is more accurate than those of the equal volume spheres, such as the homogeneous sphere and the coated sphere, with the errors of the scattering cross-section reduced by more than 10.7%. The calculated scattering phase function of the multi-component model is basically in good agreement with the experimental results. Compared to the normal growth phase, the lipid enrichment during the lipid-rich phase leads to a sharp increase in the scattering cross-section by three to four times, while the absorption cross-section remains stable. Remarkably, in the starch-rich phase, the abundant production of starch results in a reduction of two to three times in the absorption cross-section compared to the normal growth phase, while the scattering cross-section varies little. The results can provide basic data and theoretical support for the design and optimization of photobioreactors.

Thermochromism film can automatically adjust its emittance without additional energy consumption, which shows great prospect in the application of spacecraft thermal control. However, it is still challenging to achieve a large infrared emittance at a high temperature and emittance tunability of the thermochromism film. In this work, we propose a V O 2 particle-based intelligent metasurface for spacecraft thermal control, which consists of a square lattice array of hollow spheroidal V O 2 particles on Au substrate. The metasurface with a V O 2 particle having a large aspect ratio (∼10) displays perfect emission throughout the entire mid-infrared spectral range. The emittance tunability can exceed 0.63 with total normal emittance of 0.85. The underlying mechanisms involved in the metasurface are attributed to particle-dependent scattering, by which the infrared emittance is dramatically enhanced for the metallic state and restricted for the dielectric state. In addition, the infrared emittance at a high temperature and emittance tunability of the metasurface remain large for incident angles up to 60°. To the best of our knowledge, this work proposes the first thermochromism film structure with perfect infrared emission, which could accelerate the development and practical application of the thermochromic film in the field of spacecraft.