Asymmetric Energy Research Articles

Bipolar thermoelectricity in S/I/NS and S/I/SN superconducting tunnel junctions

Recent studies have shown the potential for bipolar thermoelectricity in superconducting tunnel junctions with asymmetric energy gaps. The thermoelectric performance of these systems is significantly impacted by the inverse proximity effects present in the normal-superconducting bilayer, which is utilized to adjust the gap asymmetry in the junction. Here, we identify the most effective bilayer configurations, and we find that directly tunnel-coupling the normal metal side of the cold bilayer with the hot superconductor is more advantageous compared to the scheme used in experiments. By utilizing quasiclassical equations, we examined the nonlinear thermoelectric junction performance as a function of the normal metal film thickness and the quality of the normal-superconducting interface within the bilayer, thereby determining the optimal design to observe and maximize this nonequilibrium effect. Our results offer a roadmap to achieve improved thermoelectric performance in superconducting tunnel junctions, with promising implications for a number of applications.

Nonlinear dynamics of asymmetric bistable energy harvesters

The paper investigates asymmetries effects over a nonlinear vibration energy harvester dynamics. The asymmetric system performance is compared with symmetric ones. Different asymmetry levels on restoring force and gravity action are investigated from a system-sloping angle variation. Bifurcation diagrams and basins of attraction are used to examine the local and global characteristics underlying dynamical systems under different excitation energy. The results show the adverse effects of asymmetries on system dynamics. They also reveal ways to overcome them by canceling asymmetric influence from optimal sloping angle values and improving asymmetric system performance over symmetrical ones. This comprehensive numerical study provides novel valuable insights into asymmetrical energy harvester dynamics, a wide and still less explored topic.

Numerical study for nonlinear hydrodynamic coefficients of an asymmetric wave energy converter

In this study, the nonlinear dynamic behavior of an asymmetric Wave Energy Converter (WEC) was studied on a 1/11-scale model based on a numerical and experimental method in a regular wave field. The numerical analysis involved both frequency-domain and time-domain solutions. The frequency-domain solution was based on linear potential flow theory using the WAMIT® model whereas the time-domain solution was based on the Reynolds-Averaged Navier-Stokes (RANS) equation using the OpenFOAM® model. The pitch response amplitude operators obtained from the numerical results were compared with experimental data. Additionally, the nonlinear dynamic behavior of the asymmetric WEC due to various wave heights and periods obtained through the experiments were compared with the OpenFOAM results. Wave excitation moments and hydrodynamic coefficients based on the linear solution approach were separately obtained for the fixed asymmetric WEC induced by waves and the forced oscillating motion with OpenFOAM. Moreover, frequency-domain solutions based on linear potential flow theory were obtained in order to ascertain the nonlinear effects observed in the OpenFOAM results. It was found that a higher motion amplitude could be attributed to nonlinear hydrodynamic coefficients on the asymmetric WEC calculated by the forced oscillation motion of the RANS-based solution.

Rationally Engineered Vertically Aligned β‐Ga2−xWxO3 Nanocomposites for Self‐Biased Solar‐Blind Ultraviolet Photodetectors with Ultrafast Response

AbstractWith the astonishing advancement of present technology and increasing energy consumption, there is an ever‐increasing demand for energy‐efficient multifunctional sensors or transducers based on low‐cost, eco‐friendly material systems. In this context, self‐assembled vertically aligned β‐Ga2−xWxO3 nanocomposite (GWO‐VAN) architecture‐assisted self‐biased solar‐blind UV photodetection on a silicon platform, which is the heart of traditional electronics is presented. Utilizing precisely controlled growth parameters, the formation of W‐enriched vertical β‐Ga2−xWxO3 nanocolumns embedded into the W‐deficient β‐Ga2−xWxO3 matrix is reached. Detailed structural and morphological analyses evidently confirm the presence of β‐Ga2−xWxO3 nanocomposite with a high structural and chemical quality. Furthermore, absorption and photoluminescence spectroscopy explains photo‐absorption dynamics and the recombination through possible donor–acceptor energy states. The proposed GWO‐VAN framework facilitates evenly dispersed nanoregions with asymmetric donor energy state distribution and thus forms build‐in potential at the vertical β‐Ga2−xWxO3 interfaces. As a result, the overall heterostructure evinces photovoltaic nature under the UV irradiation. A responsivity of ≈30 A/W is observed with an ultrafast response time (≈350 µs) under transient triggering conditions. Corresponding detectivity and external quantum efficiency are 7.9 × 1012 Jones and 1.4 × 104%, respectively. It is believed that, while this is the first report exploiting GWO‐VAN architecture to manifest self‐biased solar‐blind UV photodetection, the implication of the approach is enormous in designing electronics for extreme environment functionality and has immense potential to demonstrate drastic improvement in low‐cost UV photodetector technology.

Nonlinear dynamics analysis of enhancing energy harvesting from intense vibration based on improved asymmetric bistable stochastic resonance model

While the improved bistable energy harvesting (IBEH) system is excellent at harvesting energy from weak excitation signals, it is still inadequate at harvesting energy from intense excitation signals. Due to the strict resonance problem, energy harvesting strategies for intense excitation modes are not yet mature. Stochastic resonance seems to be a suitable solution for intense excitation vibration energy harvesting. An asymmetric improved bistable energy harvesting (AIBEH) system is proposed to address this issue by varying the position of the fixed-end magnet. Combining the AIBEH system with stochastic resonance theory and simulation results demonstrate that by simultaneously moving the fixed-end magnet up or down, the depth of a single potential well can be reduced while maintaining two stable state points, decreasing the slope of the potential wall on one side and increasing the dynamic output of the system under intense excitation signals. The research develops a mathematical model of the AIBEH system and numerically solves the electromechanical coupling control equations. The potential energy of three systems is analyzed: IBEH, AIBEH, and ABEH (asymmetric bistable energy harvesting). The Kramers rate and signal-to-noise ratio are derived for an asymmetric bistable system under a harmonic excitation signal and Gaussian white noise. In addition, the effects of harmonic excitation and additional noise on the AIBEH capture performance are investigated. The simulation results indicate that the harvesting performance of AIBEH is superior to that of IBEH at intense excitation.

Structural, opto-electrical, and band-edge properties of full-series multilayer SnS1-xSex (0≤x≤1) compounds with strong in-plane anisotropy

Two-dimensional (2D) semiconductors with black phosphorus (BP) structure have recently received considerable attention on the realization of polarized optoelectronic device, axial-dependent carrier transport, and asymmetric 2D electronic and energy device owing to the strong in-plane anisotropy presented in the van der Waal plane. In this work, multilayered SnS1-xSex chalcogenides of x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and x = 1 were grown by chemical vapor transport and then exfoliated on a SiO2/Si substrate for further optical characterization. Polarized micro-Raman experiment and theoretical Raman-mode calculation simultaneously demonstrate strong in-plane anisotropy with the maximum Raman intensity of the armchair (AM) chain vibration mode (Ag) shows mutual orthogonality to the zigzag (ZZ) chain-oriented mode (B1g) in the full-series multilayer SnS1-xSex (0 ≤ x ≤ 1). For the intermediate compositions between x = 0.2 and x = 0.8, a crucial physical mechanism as “symmetry breaking” has been proposed to account for the increased number of separated Ag and B1g modes with different energies as compared to those detected for the binary compounds of orthorhombic SnS and SnSe. For the band-edge anisotropy, the bandgap value of ZZ polarized direction is shown to be lower than that of the AM direction for each of the SnS1-xSex compounds evidenced by polarized-thermoreflectance experiments and first-principles calculations.

Preparation of Single-Ni atom active points by anchoring Anderson polyoxometalate in HKUST-1 for efficient Symmetric/ Asymmetric device energy storage and electrocatalytic overall water splitting

We explore and synthesize hollow polyoxometalate-based metal–organic framework (POMOF) nanomaterial {Cu(NH4)2NiMo6O24H6}@HKUST-1 (HRBNU-2) with single-atom sites (SASs) by one-step solution method. It exhibits high specific capacitance (978.50F g−1) in neutral electrolyte. Symmetrical/Asymmetrical devices can light four Red Light Emitting Diodes (RLEDs)/one RLED on for 14 min. For electrocatalytic water splitting, the overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline medium are 192.98 mV (η100) and 405.38 mV (η100). The double-layer capacitance (Cdl) of HRBNU-2 is 269.23 mF cm−2, reaching about 4.43 times of {Cu2(NH4)2Mo7O24}@HKUST-1 (HRBNU-3) and about 12.70 times of HKUST-1. Moreover, the device assembled by HRBNU-2 as cathode and anode, requires only 1.61 V cell voltage to achieve current density of 10 mA cm−2 and obtain stability of 100 h. Meanwhile, comparative study of HRBNU-3 system with similar structural composition is synthesized to illustrate that the synergy of SASs(Ni) and Mo in well-defined structures plays important role in the study of efficient overall water splitting and supercapacitance performance.

Power performance of an asymmetric wave energy converter near a partial reflection wall

Wave power absorption of a heaving-body wave energy converter (HBWEC) can be improved by making the device highly asymmetric and deploying it near a coastal wall, harbour pier, or breakwater. However, the coupling between the geometric asymmetry of the HBWEC and the partial reflecting boundaries of the various walls and the consequential influence on the power performance of the HBWEC are unclear. This research aims to fill this gap. A semi-analytical model based on the linear potential flow theory is proposed to deal with an HBWEC with an arbitrary bottom shape and a partial reflection wall. The degree of asymmetry (DoA) of the HBWEC and the reflection rate of the wall are mathematically defined. Results show that the wall increases the power performance of an HBWEC by increasing the reflected wave energy through an increase in the reflection rate. Practically, an HBWEC should have a larger DoA to make it more immune to the change of the reflection rate and therefore more adaptable to different situations. These findings could offer recommendations for the design and deployment of an HBWEC according to the properties of the wall, improving wave power absorption efficiency and avoiding unnecessary costs due to improper design.

Development and robustness investigation of track-based asymmetric nonlinear energy sink for impulsive response mitigation

Nonlinear energy sinks (NESs) are known for their capacity of resonating with a wide range of frequencies. However, the occurrence of resonance in NESs strongly depends on the input energy level. To further enhance energy as well as frequency-related robustness and tailor the robust performance to the need of engineering structures, track asymmetric nonlinear energy sinks (TANESs) are proposed in this study. Integrating the merits of two existing mass dampers, TANESs are able to broaden the energy range for effective response mitigation toward both the upper and lower limits. First, the theoretical model of TANESs is developed and validated through experiments on a two-story frame structure. The validated model is then applied to analytically derive the fundamental dynamics of the standalone TANES under impulsive and harmonic excitation. Subsequently, the robust performance of the TANES predicted by the analytical results is numerically investigated when the structure, considering natural frequency variations, is subjected to impulsive excitation of different amplitudes. Finally, the control characteristics and applicable situations of the TANES and other comparable mass dampers are discussed. The results show that the TANES can act as a well-tuned linear mass damper when the input energy is below a certain level and perform more effectively on frequency-decreased structure as the energy level further increases. As decrease in structural frequency is often caused by damages under stronger excitation, TANESs are considered to be a suitable control strategy for engineering structures in practice.

Minimizing Energy Depletion Using Extended Lifespan: QoS Satisfied Multiple Learned Rate (ELQSSM-ML) for Increased Lifespan of Mobile Adhoc Networks (MANET)

Mobile Adhoc Networks (MANETs) typically employ with the aid of new technology to increase Quality-of-Service (QoS) when forwarding multiple data rates. This kind of network causes high forwarding delays and improper data transfer rates because of the changes in the node’s vicinity. Although an optimized routing technique to transfer energy has been used to lessen the delay and improve the throughput by assigning a proper data rate, it does not consider the objective of minimizing the energy use, which results in less network lifetime. The goal of the proposed work is to minimize the energy depletion in a MANET, which results in an extended Lifespan of the network. In this research paper, an Extended Life span and QSSM-ML routing algorithm is proposed, which minimizes energy use and enhances the network lifetime. First, an optimization problem is formulated with the purpose of increasing the network’s lifetime while limiting the energy utilization and stability of the path along with residual. Second, an adaptive policy is applied for the asymmetric distribution of energy at both origin and intermediate nodes. In order to achieve maximum network lifespan and minimal energy depletion, the optimization problem was framed when power usage is a constraint by allowing the network to make use of the leftover power. An asymmetric energy transmission strategy was also designed for the adaptive allocation of maximum transmission energy in the origin. This made the network lifespan extended with the help of reducing the node’s energy use for broadcasting the data from the origin to the target. Moreover, the node’s energy use during packet forwarding is reduced to recover the network lifetime. The overall benefit of the proposed work is that it can achieve both minimal energy depletion and maximizes the lifetime of the network. Finally, the simulation findings reveal that the ELQSSM-ML algorithm accomplishes a better network performance than the classical algorithms.

Asymmetric Complex Plasma Interaction Energy in the Poisson–Boltzmann Plus Hole Approximation

Asymmetric Complex Plasma Interaction Energy in the Poisson–Boltzmann Plus Hole Approximation

Nonreciprocal supercurrent in thin film of type II superconducting Sn

The nonreciprocal supercurrent, namely the superconducting diode effect, can be realized with various mechanisms. The recent study has demonstrated the superconducting diode effect on thin films under the out-of-plane magnetic field, owing to the asymmetric Bean–Livingston barrier on the edge. In this study, we investigated the nonreciprocal supercurrent in a thin film of Sn deposited on a diamond substrate. The Ginzburg-Landau parameter κ in the thin film was estimated to be 0.711 which is slightly higher than (0.707). We observed the nonreciprocal supercurrent owing to the asymmetric energy barrier for flux penetration on the edge.

Accelerating electrochemical CO2 reduction to multi-carbon products via asymmetric intermediate binding at confined nanointerfaces

Electrochemical CO2 reduction (CO2R) to ethylene and ethanol enables the long-term storage of renewable electricity in valuable multi-carbon (C2+) chemicals. However, carbon–carbon (C–C) coupling, the rate-determining step in CO2R to C2+ conversion, has low efficiency and poor stability, especially in acid conditions. Here we find that, through alloying strategies, neighbouring binary sites enable asymmetric CO binding energies to promote CO2-to-C2+ electroreduction beyond the scaling-relation-determined activity limits on single-metal surfaces. We fabricate experimentally a series of Zn incorporated Cu catalysts that show increased asymmetric CO* binding and surface CO* coverage for fast C–C coupling and the consequent hydrogenation under electrochemical reduction conditions. Further optimization of the reaction environment at nanointerfaces suppresses hydrogen evolution and improves CO2 utilization under acidic conditions. We achieve, as a result, a high 31 ± 2% single-pass CO2-to-C2+ yield in a mild-acid pH 4 electrolyte with >80% single-pass CO2 utilization efficiency. In a single CO2R flow cell electrolyzer, we realize a combined performance of 91 ± 2% C2+ Faradaic efficiency with notable 73 ± 2% ethylene Faradaic efficiency, 31 ± 2% full-cell C2+ energy efficiency, and 24 ± 1% single-pass CO2 conversion at a commercially relevant current density of 150 mA cm−2 over 150 h.

Calculating the Electrons Distribution Function for Gallium Arsenide at Low Fields by Solving the Boltzmann Transport Equation.

The electron distribution function for gallium arsenide GaAs was calculated by using the Boltzmann transition equation in the central valley , for a range of low fields relative to the threshold field (E0 = 5.95Kv/cm) (0.3-1)E0. To obtain the distribution function, the Boltzmann transport equation was solved using a mechanism that combines the analytical and numerical methods. Analytical method involving extension of the Legendre polynomial was used and the effect of polar optical scattering was introduced as the dominant scattering mechanism in this research, as well as the effect of an asymmetric energy band structure with spherical energy surfaces in the central valley. After obtaining a partial differential equation of the second order, it is solved numerically after separation process for the variables using the direct matrix method in energy space by building a mathematical program using MATLAB. In this study, a system with dimensions of 360 × 360 was built, and the rate of change in energy was taken as 0.001.The computational system was tested by applying low electric fields, and the distribution function that was obtained had a Maxwellian distribution at very low fields, and it shifted from the Maxwellian distribution at higher fields close to the threshold field, and the results obtained were agree with previous results. While this system did not give accurate results at the high-electric fields.

Investigating valley-dependent current generation due to asymmetric energy dispersion for charge-transfer from a quantum dot to single-walled carbon nanotube

Single-wall carbon nanotubes (SWCNT), which consist of a two-dimensional hexagonal lattice of carbon atoms, possess unique mechanical, electrical, optical and thermal properties. SWCNT can be synthesized in diverse chiral indexes to determine certain attributes. This work theoretically investigates electron transport in different directions along SWCNT. The electron studied in this research transfers from the quantum dot that can possibly move to the right or left direction in SWCNT with different valley-dependent probability. These results show that valley polarized current is present. The valley current in the right and left directions has a composition of valley degrees of freedom where its components (K and K′) are not identical. Such a result can be traced theoretically by certain effects. That firstly is the curvature effect on SWCNT in which the hopping integral between pi electrons from the flat graphene is altered, and another is curvature-inducing sigma -pi mixture. Due to these effects, the band structure of SWCNT is asymmetric in certain chiral indexes leading to the asymmetry of valley electron transport. Our results exhibit that the zigzag chiral indexes is the only type making electron transport symmetrical that is different to the result from the other chiral index types which are the armchair and chiral. This work also illustrates the characteristic of the electron wave function propagating from the initial point to the tip of the tube over time, and the current density of the probability in specific times. Additionally, our research simulates the result from the dipole interaction between the electron in QD and the tube that impacts the lifetime of the electron being in QD. The simulation portrays that more dipole interaction encourages the electron transfer to the tube, thereby shortening the lifetime. We as well suggest the reversed electron transfer from the tube to QD that the time duration of such transfer is much less than the opposite transfer owing to the different orbital of the electron’s states. Valley polarized current in SWCNTs may also be used in the development of energy storage devices such as batteries and supercapacitors. The performance and effectiveness of nanoscale devices, including transistors, solar cells, artificial antennas, quantum computers, and nano electronic circuits, must be improved in order to achieve a variety of benefits.

New electropolymerized triphenylamine polymer films and excellent multifunctional electrochromic energy storage system materials with real-time monitoring of energy storage status

Multifunctional intelligent electrochromic energy storage with real-time monitoring of energy storage level by color change has become the extremely attractive researches for the development of electrochemical energy storage systems. Herein, three novel triphenylamine-based organic monomers with star-shaped donor–acceptor structure are designed and synthesized to successfully obtain the corresponding three polymer films with different and rich color switching by electrochemical polymerization via the coupling between peripheral triphenylamine groups. Based on these three polymer films as the electrodes, a fast switching electrochromic property with a large optical contrast of 80.5 % in the visible region and a high coloration efficiency of 277.21 cm2·C−1, which are one of the best results among TPA-based electrochromic materials, is achieved for the polymer pPh-4TPA with the pyrazino[2,3-g]quinoxaline acceptor core. Meanwhile, pPh-4TPA also shows high specific capacitance of up to 423F·g−1 (475F·cm−3), high capacity of 115.3 mAh·g−1 and unparalleled rate performance. The assembled asymmetric electrochromic energy storage devices based on pPh-4TPA polymer films exhibited maximum energy density of 105.12 Wh·kg−1 (107 mWh·cm−3) and power density of 45 kW·kg−1 (45.9 W·cm−3), which are both the highest energy and power densities among the pure organic electrochromic pseudocapacitors ever reported, simultaneously accompanied by reversible color changes in appearance during charging and discharging process.

Numerical Investigations of Asymmetric Inerter Nonlinear Energy Sink for Vibration Control

Nonlinear energy sinks (NESs) and tuned mass damper (TMD) have achieved excellent control performance. However, their energy and frequency robustness, as well as a large desired slide mass, impede their wide application in practice. To address this limitation, this paper proposes an asymmetric NES that combines two types of inerter NES, the AsymI-1 NES and AsymI-2 NES, to improve the damping robustness of traditional control devices and reduce the damper mass. In addition, the distinction is achieved by adding an inerter between the sliding damper and the top or bottom story. Further, the mathematical formulation of the asymmetric inerter NES is deduced. The working principle of the proposed asymmetric inerter NES is presented, and motion equations of the asymmetric inerter NES-attached system are derived. The proposed asymmetric inerter NES is optimized using impulsive excitation to analyze its energy and frequency robustness. The control performance and wavelet spectrum analyses of the asymmetric inerter NES are conducted under the action of earthquakes. The analysis results show that combining the two asymmetric inerter NESs can help to absorb seismic energy rapidly, limit structural reaction, and ensure good energetic and frequency robustness. Furthermore, the proposed asymmetric inerter NES can significantly decrease the stroke requirement and damper mass.

Formation of local heterogeneity under energy collection in neural networks

Static distribution of intracellular and extracellular ions can induce the spatial distribution of electric field in the cell, while stochastic diffusion and propagation of ions can generate channel current accompanied by the magnetic field. In fact, the field energy (including magnetic and electric fields) in each cell or neuron can be changed under external stimuli or the deformation of shape. Furthermore, energy pumping occurs, and the synaptic connection is created adaptively to keep energy balance when more neurons are clustered in the same region because of electromagnetic field superposition. For a synchronous and homogeneous network, all neurons keep energy balance with the adjacent neurons, and the network becomes uniform and identical. For cardiac tissue and biological media, local heterogeneity such as sinoatrial node can emit continuous wave front, and target waves are propagated to regulate the neural activities and heartbeat rhythm. In this paper, the Hamilton energy in a simple neuron model is calculated according to the Helmholtz theorem, and more neurons are clustered to build a regular network (chain network and square array). The creation and growth of synapse connection are controlled to pump energy, and local heterogeneity is formed by taming one intrinsic parameter when more energy is accumulated in a few neurons in the network. These results indicate that asymmetrical energy transport will induce the occurrence of heterogeneity in the network, and adaptive synaptic regulation on neurons is activated to keep local energy balance before reaching perfect synchronization. When external stimuli with diversity in intensity are applied, neurons are excited with energy diversity, and possible shape deformation is induced to keep local energy balance. As a result, heterogeneity is developed in a local area.

Concept of Very-Asymmetric lepton Collider for dark matter search

Accelerator-based searches for dark matter are aiming for high sensitivity and need an experimental setup with high luminosity. This field of research is often called intensity frontier physics. One of the best motivated portals of interaction between dark matter and ordinary matter is a dark photon which could be observed as a resonance in the invariant mass of the decay products. Electron–positron collisions are known to be the cleanest interaction for such a study. In this paper we propose a scheme for a collider which allows for a luminosity of a few orders of magnitude higher than could be obtained in a conventional symmetric collider and with a few times higher accessible mass than is possible using a positron beam and a fixed target approach. The key concept is based on asymmetric energies: a high-energy circulating positron beam and a low-energy high-intensity electron beam, and optimization of the beam interaction region. We present here a configuration of a collision region of 10 MeV electron and 4 GeV positron beams.

Design and experimental investigation of an asymmetric piezoelectric energy harvester based on galloping

This article presents an asymmetric piezoelectric energy harvester for scavenging wind energy at low wind speed. The piezoelectric beam undergoes bending and torsional vibration simultaneously caused by eccentric distance. The different asymmetric experimental prototypes are made to investigate the performance of the proposed energy harvester. The results show that the threshold wind speed is negatively correlated with the offset distance. And the output power decreases with the increase of eccentric distance, which requires a tradeoff between the onset wind speed and power. When the eccentric distance is 0 mm, the maximum output power of the energy harvester can reach 3.822 mW.