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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]

• A smart modulator with wideband modulation across three modes is proposed. • Optical properties are optimized by combining the RCWA method and GA. • Obtain a high transmissivity, absorptivity, and reflectivity for the corresponding mode. • Demonstrate excellent performance for thermal protection and modulation. Optical components with switchable optical properties have garnered significant attention due to their wide range of potential applications in the fields of optical detection, radiative cooling, and energy conservation, etc. Most modulators focus on modulating a single parameter within a narrow spectral range, which often falls short of meeting the increasing demands of advanced photonic systems. In this study, we introduce a smart modulator capable of wideband modulation across three modes: transmission, absorption, and reflection. This modulation is triggered by the temperature-dependent phase transition of Vanadium dioxide (VO 2) and In 3 SbTe 2 (IST). We optimized the optical properties of the smart modulator using a combination of the Rigorous Coupled Wave Analysis method and Genetic Algorithm. As a result, we achieved average transmissivity, absorptivity, and reflectivity values of 0.785, 0.812, and 0.798, respectively, across the spectral range of 2.5 to 15 µm for each corresponding mode. Importantly, the multimode modulation performance remains excellent even at large incident angles. Furthermore, we demonstrate the exceptional performance of the smart modulator in practical applications, taking thermal fuses as an example. This showcases its effectiveness in thermal protection and modulation. The development of such wideband multimode smart modulators holds the potential to expedite the creation of compact, efficient, and multifunctional optical systems. [ABSTRACT FROM AUTHOR]

Hybrid bulk acoustic wave and surface acoustic wave (BAW/SAW) devices attract extensive interests due to their high electromechanical coupling coefficient and quality factor. In this study, longitudinal BAW coupled SAW resonators with piezoelectric AlN inter-digital transducers (IDT) were simulated and fabricated on diamond substrates to increase the working frequency as well. The simulated figure of merit value is 104, 123 % improved comparing with the corresponding metal IDT of 46.5. The frequency response spectrum of single port reflection (S11) shows dominant harmonic resonance at 913 MHz with electromechanical coupling coefficient of 2.16 % and quality factor of 913. These results indicate mutual transductions between BAW and SAW occur with sufficient efficiency in hybrid structures, which is analyzed and interpreted by equivalent acoustic impedance theory. [Display omitted] • Diamond based longitudinal BAW coupled SAW resonators were designed and fabricated. • High figure of merit and working frequency can be achieved for the SAW devices. • The simulated figure of merit value is 104 on an Ag/AlN/Mo/Diamond/Si structure. • 913 MHz resonance with bandwidth of 2.16 % and quality factor of 913 was observed. • BAW-SAW mutual transduction is analyzed by equivalent acoustic impedance theory. [ABSTRACT FROM AUTHOR]

Currently, banana harvest still relies on manual operation with high labor intensity. With an aging global population, it is important to develop a machine to replace the manual harvesting of bananas to increase sustainability. In the area of robotic fruit harvest, most of the existing studies have used one single manipulator to grip the fruit. However, unlike other fruits, the weight of a banana bunch (25–40 kg) would be too heavy for one single manipulator. To solve this problem, this paper proposes a flexible supporting device, which was introduced to cooperate with the manipulator to complete banana harvest. The supporting device was designed to hold the bottom and the weight of the banana bunch. It included two parts: the flexible contact part and the height difference self-adjusting part. The shape adaptability, size adaptability, and height difference adaptability of the proposed supporting device were studied in this paper. The process of supporting bananas was also simulated and analyzed. The stiffness and stress properties of the device during this process were studied. The results showed that the flexible supporting device had a good adaptive performance for supporting different shapes and sizes of objects. During the supporting process, the device worked stably and reliably and caused small stress on the banana skin. Finally, a prototype of the supporting device was used to further verify the performance of the device. This research can promote the mechanization and automation progress of the harvesting of such a complex crop as bananas. [ABSTRACT FROM AUTHOR]

• Optical constants of protein, carbohydrate and lipid were experimentally determined. • Isolations of protein, lipid and carbohydrate from Chlorella sp. were conducted. • Fitted formula of the refractive index was presented. An accurate knowledge of optical constant of protein, lipid and carbohydrate is important for analyzing radiative transport between cells. However, it is difficult to measure precisely the optical constant of these elements due to the complicated sample-making and the limitation of traditional measurement method. In this work, the double optical pathlength transmission method and the ellipsometry method (DOPTM-EM) were used to obtain the optical constants of protein, lipid and carbohydrate of Chlorella sp. (both solid-state and solution-state), solution-state egg protein and solution-state sucrose in the spectral range 300-1700 nm. Isolations of protein, lipid and carbohydrate from Chlorella sp. were conducted. For different types and states of protein, lipid and carbohydrate, the optical constants of these samples are different from each other. The refractive indices of protein and carbohydrate have obvious relationship with the existing state. A significant difference of absorption indices can be observed between the solution-state protein of Chlorella sp. and the egg protein. It is indicated that the amino acids composition of solution-state protein of Chlorella sp. differs from the egg protein. The absorption indices of solution-state carbohydrate do not agree with the solution-state sucrose. For the sake of applications, the fitted formula of the refractive index as a function of wavelength is presented. [ABSTRACT FROM AUTHOR]

This paper describes an innovative electro-acoustic coupling structure with a Patterned Piezoelectric film as Inter-Digital Transducer (PP-IDT) on the diamond substrate for Surface Acoustic Wave (SAW) devices of better quality factor and frequency resolution. Theoretical analysis and Finite Element Method (FEM) are employed to investigate the dependence of microwave impedance characters on the thickness of piezoelectric and metal electrode layers. The systematic studies show that the PP-IDT structure can excite the mechanical vibration on the top surface of diamond substrate and derive the SAW. The quality factor increases remarkably in excess to 104 since the SAW is propagating below the diamond surface with little interface loss and transmission loss. Unlabelled Image • Diamond based piezoelectric layer is patterned as inter-digital transducer. • Quality factor of surface acoustic wave devices can be improved greatly. • Thickness of piezoelectric and electrode layer affects the performance. • Maximum quality factor is observed at optimal electrode thickness. [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]

The contact interaction between compliant mechanisms and external objects is a common occurrence in the field of grasping and manipulation. However, accurately modeling the large deformation and contact force/stress remains a challenging task. This paper presents a contact analysis method to evaluate the deformation and normal contact force/stress of compliant mechanisms with general-shape beams. The general beams are modeled by using the chained pseudo-rigid-body model (CPRBM). On basis of CPRBM framework, linear and distributed contact springs are introduced at the interface to represent the contact force. A numerical method is established to fast calculate the boundary penetrations, and a contact stiffness formulation is proposed based on the theory of elasticity. Then, the effect of contact interaction can be evaluated by the contact potential energy of contact springs, which is part of the system's total potential energy. By minimizing the potential energy function of the compliant system, the static equilibrium configuration and contact force/stress can be obtained easily. Numerical examples are used to verify the feasibility and accuracy of the proposed method. • A large-deflection contact analysis method considering contact stress distribution. • The large deformation of compliant mechanism is modeled by using CPRBM. • Linear contact springs are introduced to represent contact force/stress. • An analytical formulation of contact stiffness is established. • The proposed method is simple and straightforward. [ABSTRACT FROM AUTHOR]

The achievement of low-resistance connection in REB2C3O7-z (REBCO, RE = Y, Gd) coated conductors (CCs) has become one of the strategic factors for magnet applications. In this letter, we fabricated low-resistivity (Rsj = 4.9 nΩ·cm2) Ag-diffusion joints of REBCO CC by improving the interface connection of the Ag stabilizer. The effective contact area at the interface between two Ag stabilizers can be increased by polishing the surface of the Ag stabilizers, which can reduce joint resistance (Rj). Compared with a traditional diffusion temperature (400 °C), diffusion bonding of the Ag stabilizers at higher temperatures (800 or 850 °C, typical connection temperatures for superconducting joint) can promote interface connection between two Ag stabilizers. The oxygen content in REBCO will be reduced due to diffusion bonding at higher temperatures. Therefore, we etched some microchannels that serve as the fast oxygen diffusion paths on the surface of the Ag stabilizers to help restore the oxygen content, thereby recovering critical current (Ic) and reducing Rj. The connection mechanism of the interface between two Ag stabilizers was investigated through the cross-sectional analysis and delamination of the joint part. In addition, the REBCO layer can be completely peeled off and almost retain the original Ic by diffusion bonding of the Ag stabilizers at higher temperatures. This fabrication technique is a unique practicable solution to reduce the Rj for the CC with thin Ag stabilizers and improve the peeling quality of the REBCO layer for efficiently fabricating the superconducting joint. [ABSTRACT FROM AUTHOR]

The YBa2Cu3O7-x (YBCO) coated conductor (CC) is one of the most promising superconducting materials because of their high critical current (Ic) and low dependency of the Ic on the external magnetic field. For superconducting applications, a large number of joints are required to join relatively short YBCO CC tapes. In this paper, we study the electromechanical behavior of lap-jointed YBCO CC tapes fabricated by etching Cu stabilizer at its service temperatures (77 K) under self-field. The effects of etching Cu stabilizer on Ic and joint resistance (Rj) of YBCO CC tapes were discussed. The Rj was reduced and the Ic values of the joints are consistent with the parent CCs tape by etching the Cu stabilizer. Preferable electrical properties under applying axial tension are achieved and proved by the axial tension tests and finite element simulations. This fabrication technique is a unique practicable solution to reduce joint resistance for YBCO CC tapes with thicker metal stabilizing layers and improving electromechanical performance in second generation high temperature superconductor (2G HTS) devices. [ABSTRACT FROM AUTHOR]

• By etching Cu stabilizer, the joint resistance (R j) can be reduced by removing the cupric oxide of the surface layer and shortening the current path between the two YBCO layers. • Preferable electrical properties under applying bending deformation are achieved and proved by the bending tests and finite element simulations. The evidently enhanced I c retention is found by bending tests. The stress and strain of the YBCO layer can be reduced due to employ thinner etching joints. • The employment of spot welding can further enhance the strength at the edges of the joint and thereby alleviate the I c degradation. The YBa 2 Cu 3 O 7 − x coated conductor (YBCO CC) is one of the most promising superconducting materials for magnet applications because of its high critical current (I c) and low dependency of the I c on the external magnetic field. For magnet applications, plenty of joints are required to meet the connection of relatively short YBCO CC tapes. The bending properties of the joints inevitably become one of the critical factors that determine the performance of the superconducting magnet. In this paper, we fabricated the joints of YBCO CC tapes by etching Cu stabilizer and studied their bending properties under various bending diameter at 77 K and self-field. Compared with the soldering joint, lower joint resistance (R j) and preferable electrical properties under applying various bending deformation were achieved and proved by the bending strain tests and finite element simulations. This fabrication technique is a unique practicable solution to reduce the R j and improve the bending properties for the joints of YBCO CC tapes with thicker metal stabilizing layers in second generation high temperature superconductor (2G HTS) applications. [ABSTRACT FROM AUTHOR]