With the scarcity of water resources in various regions, the pressure on water supply projects is also increasing, which has led to a sharp increase in the water hammer effect in water supply pump ...projects. In response to this issue, the study proposes to apply a unidirectional pressure regulating tower based on mechanical hydraulic technology to water hammer protection in water supply pumps. In addition, the study also optimizes the calculation method of water hammer and designs one simulation software, which is used to simulate and analyze the proposed water hammer protection measures. The study first determines through simulation software that the optimal initial water level of the unidirectional pressure regulating tower is 2m and the optimal diameter of the make-up water pipe is 600 mm. Afterwards, simulation analysis is conducted on different water hammer protection measures, and it is found that the maximum pressure of the water hammer under the proposed protection measures is the lowest, at 14.8m, which was lower than the comparison measures. In addition, according to expert ratings, the average protective effect rating of protective measure 1 by relevant technical personnel is 9.4 points, which is better than the comparative measure. The above results indicate that through the simulation analysis of hydraulic transition process based on mechanical hydraulics, it can be found that the water hammer protection measures proposed in the study have good protective functions and can effectively reduce the water hammer effect in water supply engineering.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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Combining triboelectric nanogenerator (TENG) and textile materials, wearable electronic devices show great application prospects in biomotion energy harvesting and multifunctional ...self-power sensors in this coming intelligent era. However, fabrication method by rigidly stitching two or more individual fabrics together and working mode that must cooperate with external materials, make textile-based TENG bulky, stiff, uncomfortable and hinder their range of application. Here, by using a double needle bed flat knitting machine technology, a 3D double faced interlock fabric TENG (3DFIF-TENG) is designed as self-powered, stretchable and substrate-free wearable TENG sensors (such as a bending sensor to detect arm bending degree, pressure sensors) and energy harvesting devices. Besides, due to the unique 3D structure and after improving the structure by knitting a woven fabric-TENG in the middle layer, the 3DFIF-TENG can be further used as a multifunctional sensors, such as a 3D tactile sensor. Besides, by knitting a woven fabric-TENG in the middle layer of the 3DFIF-TENG, it can be further used as a multifunctional sensor, such as a 3D tactile sensor. The substrate-free and 3D structure design in this paper may provide a promising direction for self-powered, stretchable wearable devices in energy harvesting, human motion or robot movement detection, and smart prosthetics.
Quantifying the triboelectric series Zou, Haiyang; Zhang, Ying; Guo, Litong ...
Nature communications,
03/2019, Letnik:
10, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Triboelectrification is a well-known phenomenon that commonly occurs in nature and in our lives at any time and any place. Although each and every material exhibits triboelectrification, its ...quantification has not been standardized. A triboelectric series has been qualitatively ranked with regards to triboelectric polarization. Here, we introduce a universal standard method to quantify the triboelectric series for a wide range of polymers, establishing quantitative triboelectrification as a fundamental materials property. By measuring the tested materials with a liquid metal in an environment under well-defined conditions, the proposed method standardizes the experimental set up for uniformly quantifying the surface triboelectrification of general materials. The normalized triboelectric charge density is derived to reveal the intrinsic character of polymers for gaining or losing electrons. This quantitative triboelectric series may serve as a textbook standard for implementing the application of triboelectrification for energy harvesting and self-powered sensing.
Flexible and stretchable physical sensors capable of both energy harvesting and self‐powered sensing are vital to the rapid advancements in wearable electronics. Even so, there exist few studies that ...can integrate energy harvesting and self‐powered sensing into a single electronic skin. Here, a stretchable and washable skin‐inspired triboelectric nanogenerator (SI‐TENG) is developed for both biomechanical energy harvesting and versatile pressure sensing. A planar and designable conductive yarn network constructed from a three‐ply‐twisted silver‐coated nylon yarn is embedded into flexible elastomer, endowing the SI‐TENG with desired stretchability, good sensitivity, high detection precision, fast responsivity, and excellent mechanical stability. With a maximum average power density of 230 mW m−2, the SI‐TENG is able to light up 170 light‐emitting diodes, charge various capacitors, and drive miniature electronic products. As a self‐powered multifunctional sensor, the SI‐TENG is adopted to monitor human physiological signals, such as arterial pulse and voice vibrations. Furthermore, an intelligent prosthetic hand, a self‐powered pedometer/speedometer, a flexible digital keyboard, and a proof‐of‐concept pressure‐sensor array with 8 × 8 sensing pixels are successively demonstrated to further confirm its versatile application prospects. Based on these merits, the developed SI‐TENG has promising applications in wearable powering technology, physiological monitoring, intelligent prostheses, and human–machine interfaces.
A flexible, stretchable, washable, and multifunctional triboelectric‐based electronic skin obtained by embedding a planar and designable yarn electrode network into transparent elastomer is presented for both biomechanical energy harvesting and self‐powered pressure sensing. An energy harvester, physiological monitor, prosthetic hand, real‐time pedometer/speedometer, flexible digital keyboard, and tactile sensing array are successively demonstrated in order to confirm its versatile application prospects.
Triboelectric nanogenerators (TENGs) have demonstrated their promising potential in biomotion energy harvesting. A combination of the TENG and textile materials presents an effective approach toward ...smart fabric. However, most traditional fabric TENGs with an alternating current (AC) have to use a stiff, uncomfortable, and unfriendly rectifier bridge to obtain direct current (DC) to store and supply power for electronic devices. Here, a DC fabric TENG (DC F-TENG) with the most common plain structure is designed to harvest biomotion energy by tactfully taking advantage of the harmful and annoying electrostatic breakdown phenomenon of clothes. A small DC F-TENG (1.5 cm × 3.5 cm) can easily light up 416 serially connected light-emitting diodes. Furthermore, some yarn supercapacitors are fabricated and woven into the DC F-TENG to harvest and store energy and to power electronic devices, such as a hygrothermograph or a calculator, which shows great convenience and high efficiency in practice. This low-cost and efficient DC F-TENG which can directly generate DC energy without using the rectifier bridge by harvesting energy from unhealthy electrostatic breakdown has great potential as a lightweight, flexible, wearable, and comfortable energy-harvesting device in the future.
The polaron is a quasi-particle formed by a conduction electron (or hole) together with its self-induced polarization in a polar semiconductor or an ionic crystal. Among various polarizable examples ...of complex oxides, strontium titanate (SrTiO3) is one of the most studied. Here we examine the carrier type and the interplay of inner degrees of freedom (for example, charge, lattice, orbital) in SrTiO3. We report the experimental observation of Fröhlich polarons, or large polarons, at the bare SrTiO3 surface prepared by vacuum annealing. Systematic analyses of angle-resolved photoemission spectroscopy and X-ray absorption spectra show that these Fröhlich polarons are two-dimensional and only exist with inversion symmetry breaking by two-dimensional oxygen vacancies. Our discovery provides a rare solvable field theoretical model, and suggests the relevance of large (bi)polarons for superconductivity in perovskite oxides, as well as in high-temperature superconductors.
Due to the increasingly serious environmental pollution and the extreme shortage of energy resources, harvesting clean and sustainable random energy from the environment is a scientific, effective, ...and necessary solution in the coming intelligent era. Such random and disorder energy, like that from human motion and textile-related movement, can be obtained
via
textile-based triboelectric nanogenerators (TENGs). However, research related to textile-based TENGs with mature, high-efficiency, and economical manufacturing techniques is limited. Here, by using a high-speed ring spinning method, negative Poisson's ratio yarn (NPRY) with a composite structure is designed and fabricated as a variety of intelligent device. Based on the special negative Poisson's ratio effect, NPRY combined with TENG can be used as a foundation structure to form diverse flexible textile-based electronic devices, such as an energy harvesting fabric, a self-counting yoga elastic band, and a self-powered pre-alarm cable. At the same time, NPRY-TENGs with different structures and structural parameters are systematically investigated to optimize the output performance in this work. This special, low-cost, and highly efficient NPRY as a foundation structure material has promising applications in the manufacture of all kinds of textile-based TENGs and harvesting a lot of random energy from the environment, where the random energy can be used by other electronic devices or those textile-based TENGs themselves as self-powered sensors.
Mass-manufactured stretchable negative Poisson's ratio yarn TENG as a fundamental material for environmental energy harvesting and self-powered sensors.
The recent discovery of possible high-temperature superconductivity in single-layer FeSe films has generated significant experimental and theoretical interest. In both the cuprate and the iron-based ...high-temperature superconductors, superconductivity is induced by doping charge carriers into the parent compound to suppress the antiferromagnetic state. It is therefore important to establish whether the superconductivity observed in the single-layer sheets of FeSe--the essential building blocks of the Fe-based superconductors--is realized by undergoing a similar transition. Here we report the phase diagram for an FeSe monolayer grown on a SrTiO3 substrate, by tuning the charge carrier concentration over a wide range through an extensive annealing procedure. We identify two distinct phases that compete during the annealing process: the electronic structure of the phase at low doping (N phase) bears a clear resemblance to the antiferromagnetic parent compound of the Fe-based superconductors, whereas the superconducting phase (S phase) emerges with the increase in doping and the suppression of the N phase. By optimizing the carrier concentration, we observe strong indications of superconductivity with a transition temperature of 65±5 K. The wide tunability of the system across different phases makes the FeSe monolayer ideal for investigating not only the physics of superconductivity, but also for studying novel quantum phenomena more generally.
The recent discovery of high-temperature superconductivity in iron-based compounds has attracted much attention. How to further increase the superconducting transition temperature (T(c)) and how to ...understand the superconductivity mechanism are two prominent issues facing the current study of iron-based superconductors. The latest report of high-T(c) superconductivity in a single-layer FeSe is therefore both surprising and significant. Here we present investigations of the electronic structure and superconducting gap of the single-layer FeSe superconductor. Its Fermi surface is distinct from other iron-based superconductors, consisting only of electron-like pockets near the zone corner without indication of any Fermi surface around the zone centre. Nearly isotropic superconducting gap is observed in this strictly two-dimensional system. The temperature dependence of the superconducting gap gives a transition temperature T(c)~ 55 K. These results have established a clear case that such a simple electronic structure is compatible with high-T(c) superconductivity in iron-based superconductors.
The crystallographic stacking order in multilayer graphene plays an important role in determining its electronic structure. In trilayer graphene, rhombohedral stacking (ABC) is particularly ...intriguing, exhibiting a flat band with an electric-field tunable band gap. Such electronic structure is distinct from simple hexagonal stacking (AAA) or typical Bernal stacking (ABA) and is promising for nanoscale electronics and optoelectronics applications. So far clean experimental electronic spectra on the first two stackings are missing because the samples are usually too small in size (μm or nm scale) to be resolved by conventional angle-resolved photoemission spectroscopy (ARPES). Here, by using ARPES with a nanospot beam size (NanoARPES), we provide direct experimental evidence for the coexistence of three different stackings of trilayer graphene and reveal their distinctive electronic structures directly. By fitting the experimental data, we provide important experimental band parameters for describing the electronic structure of trilayer graphene with different stackings.
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