Search

In this paper, we developed a lightweight, self-sensing electret-based dynamic vibration absorber (ESDVA) for micro-vibration suppressions. We modeled the electromechanical coupling procedure of the ESDVA based on the first principles and proposed a sensing model based on support vector regression machine (SVR). The SVR algorithm helps to linearize the original voltage generated by the electret for precise vibration sensing. A prototype of the ESDVA is fabricated, and the theoretical model and SVR algorithms are verified by experiments. According to experimental results, the ESDVA successfully reduced primary structure vibration amplitudes by up to 50% with a mass burden of 1.4% of the primary structure. The proposed sensing model achieve an accuracy rate of over 93.5% for vibration sensing and the robustness of the model was also assessed. Moreover, the advantages of the proposed electret-based sensing method over classical methods are discussed. [ABSTRACT FROM AUTHOR]

One of the crucial issues for applying electret/triboelectric power generators in the Internet of Things (IoT) is to take full advantage of specific high voltage signals and enable self-powered sensing. Therefore, inspired by Miura-origami, we present an innovative origami power generator (OPG) constructed from only one piece of electret thin film. The Miura-origami architecture realizes a generator with excellent deformability and stretchability and makes it unnecessary for any auxiliary support structure during the compress-release cycle. Various parameters of the generator are intensively investigated, including the excitation accelerations, excitation displacements, numbers of power generation units and deformation degree of the device. When stimulated with 5.0 g acceleration at 15 Hz frequency, the generator with 8 generation units can obtain an instantaneous peak-to-peak voltage and a remarkable optimum peak power of 328 V and 2152 μW at 50 MΩ, respectively. In addition, the regulable shape and multiple generation modes of the device greatly improve its applicability in various vibration energy collection requirements. Based on the above results, a hexagonal electret generator integrated with six-phase OPGs is developed as a "Buoy on Sky," after which the signal waveforms generated from internal power generators are recognized with 92% accuracy through a neural network algorithm that identifies the vibration conditions of transmission lines. This work demonstrates that a fusion of origami art and energy conversion techniques can achieve a multifunctional generator design satisfying the requirements for IoT applications. [ABSTRACT FROM AUTHOR]

A spacesuit water membrane evaporator (SWME) based on the hollow fiber membrane bundle is regarded as a promising technology for the advanced thermal management system of the next-generation spacesuit. This paper focuses on theoretical modelling and finite element analysis for the SWME and parametrical optimization. The heat transfer process of the elongated hollow fiber membranes is studied via segment modelling and energy balance method. A comprehensive Finite element analysis is conducted in different dimensions to analyze the influence of fiber tube arrangements and the size of the evaporation chamber. An SWME prototype is also developed. Heat rejection experiments are conducted to verify the theoretical analysis. The work of this paper helps to gain a deep understanding of the heat dissipation process of the hollow fiber membranes and could be referred to for further optimization of the SWME devices. [ABSTRACT FROM AUTHOR]

One of the critical issues for electret/triboelectric devices is the poor charge viability and stability in humid environments. Herein, we propose a new origami-inspired "W-tube"-shaped triboelectric nanogenerator (W-TENG) with two thin-film electrets folded based on Miura-origami. The Miura-origami fold is capable of transforming flat materials with large surface areas into reduced and compressed complex 3D structures with parallelogram tessellations. The triboelectric power generation components can thus be hermetically sealed inside the "W-tube" to avoid contact with the external humid environment. Furthermore, the elastic nature of the Miura-origami fold endows the proposed W-TENG device with excellent deformability, flexibility, and stretchability. Therefore, it is capable of harvesting kinetic energy from various directions and forms of movement, including horizontal pressing, vertical tapping, and lateral bending. The compact, light weight, and self-rebounding properties of the origami structure also make it convenient for integration into wearable devices. Various parameters of the W-TENG are intensively investigated, including the number of power generation units, original height of the device, acceleration magnitude, excitation direction, and water-proof capability. Triggered by hand tapping impulse excitation in the horizontal and vertical directions, the instantaneous open-circuit voltages can reach 791 V and 116 V with remarkable optimum powers of 691 μW at 50 MΩ and 220 μW at 35 MΩ, respectively. The outcomes of this work demonstrate the fusion of the ancient art of origami, material science, and energy conversion techniques to realize flexible, multifunctional, and water-proof TENG devices. Wearable electronics: Folding the way to flexible a power supply Researchers have used techniques from origami to engineer a flexible, resilient, water-proof power generator, which can be used with wearable devices. The device, designed by a team led by Kai Tao of China's Northwestern Polytechnical University, consists of two thin films of dielectric material, which can generate power when deformed. This structure is then folded in a Miura fold, a pattern which compresses a large surface area into a smaller area. The resulting spring-like makes the device return to its original shape after deformation while also offering compactness and flexibility together. The device generated power when tapped or bent, and the origami structure hermetically sealed the components, making the generator water-proof. With this combination of origami and material science, researchers can design and build flexible energy-harvesting devices to power wearable devices or other flexible electronics. [ABSTRACT FROM AUTHOR]