Energy Transport Research Articles

Feasibility Testing of the Bionet Sonar Ultrasound Transcutaneous Energy Transmission (UTET) System for Wireless Power and Communication of a LVAD.

To address the clinical need for totally implantable mechanical circulatory support devices, Bionet Sonar is developing a novel Ultrasonic Transcutaneous Energy Transmission (UTET) system that is designed to eliminate external power and/or data communication drivelines. UTET systems were designed, fabricated, and pre-clinically tested using a non-clinical HeartWare HVAD in static and dynamic mock flow loop and acute animal models over a range of pump speeds (1800, 2400, 3000 RPM) and tissue analogue thicknesses (5, 10, 15mm). The prototypes demonstrated feasibility as evidenced by meeting/exceeding function, operation, and performance metrics with no system failures, including achieving receiver (harvested) power exceeding HVAD power requirements and data communication rates of 10kB/s and pump speed control (> 95% sensitivity and specificity) for all experimental test conditions, and within healthy tissue temperature range with no acute tissue damage. During early-stage development and testing, engineering challenges for UTET size reduction and stable and safe operation were identified, with solutions and plans to address the limitations in future design iterations also presented.

High-Voltage Electrical Burn Requiring Urgent Scalp Reconstruction after Developing a Brain Abscess

Electrical burn injuries to the scalp are at risk of extensive tissue damage and neurological complications. We present the case of a patient who came into contact with a high-voltage power line while cherry picking, resulting in a large full-thickness scalp defect. Early on in his presentation, he developed progressive global weakness which remained relatively static during his admission. An incidental finding of an extradural abscess complicated his management, requiring urgent surgical intervention with definitive tissue coverage. The scalp was reconstructed using a free myocutaneous anterolateral thigh flap. There were no postoperative complications. Following rehabilitation, the patient was discharged home with limited functional recovery. He mobilises independently with a wheelchair and requires full-time carers.

Two stage decoherence of optical phonons in long oligomers.

Molecular vibrations are generally responsible for chemical energy transport and dissipation in molecular systems. This transport is fast and efficient if energy is transferred by optical phonons in periodic oligomers, but its efficiency is limited by decoherence emerging due to anharmonic interactions with acoustic phonons. Using a general theoretical model, we show that in the most common case of the optical phonon band being narrower than the acoustic bands, decoherence takes place in two stages. The faster stage involves optical phonon multiple forward scattering due to absorption and emission of transverse acoustic phonons, i.e., collective bending modes with a quadratic spectrum; the transport remains ballistic and the speed can be altered. The subsequent slower stage involves phonon backscattering in multiphonon processes involving two or more acoustic phonons resulting in a switch to diffusive transport. If the initially excited optical phonon possesses a relatively small group velocity, then it is accelerated in the first stage due to its transitions to states propagating faster. This theoretical expectation is consistent with the recent measurements of optical phonon transport velocity in alkane chains, increasing with increasing the chain length.

Significant influence of winter Pacific-North American pattern on spring vegetation in mid-high latitude Asia

Abstract Given that the vegetation over mid-high latitude Asia (MHA) has been more variable in recent years, it is necessary to better understand the physical causes of vegetation variations in this region. Based on the normalized difference vegetation index (NDVI), this study reveals a close linkage of the variability of spring (April-May) vegetation in MHA to the winter (December-January-February) Pacific-North American (PNA) pattern. When the winter PNA pattern lies in the positive phase, the NDVI tends to decrease in most parts of the MHA region during the following spring. Further analysis suggests that the lagged influence of winter PNA on spring atmospheric circulations and hence the vegetation in MHA is accomplished by the stratospheric pathway. The positive PNA phase can enhance the upward transport of wave energy into the stratosphere over the high latitudes in winter through the linear constructive interference of zonal wavenumber 1 (WN1), consequently leading to a weaker polar vortex in the stratosphere during February-March. Subsequently, the weakened polar vortex signal propagates downward from the stratosphere to the troposphere, inducing the negative Arctic Oscillation (AO)-like circulation with an anomalous cyclonic circulation dominating the MHA region in spring. The anomalous cyclonic circulation further cools the surface air temperature in MHA via modulating downward solar radiation and temperature advection, resulting in a decrease of spring NDVI in situ.

Light Transfers Through a Koch Shape Cloud

AbstractModeling radiative transfer in a 3D cloudy atmosphere is critical to climate projections. A recently developed fast 3D radiation parameterization scheme gains some success in quantifying horizontal radiative transfer through cloud sides using cloud area fraction. Based on 3D Monte Carlo simulations of radiative transfer through an idealized single‐layer cloud with Koch‐shaped fractal geometry edges, here we show that radiative energy transport through cloud sides correlates more significantly with cloud area fraction than with cloud perimeter length. The results exemplify the importance of accounting for the horizontal radiative energy exchanges between cloud‐free and cloudy regions with cloud area fraction. Results from additional sensitivity simulations show that increased cloud vertical extent often enhances cloud‐side sunlight leak more significantly than cloud‐side sunlight interception. At low sun elevations, cloud‐side sunlight interception is enhanced more than cloud‐side sunlight leak does with the increase of cloud mass.

Coupled EMAG-CFD-Thermal analysis of a novel SST system utilizing forced-liquid cooling with biodegradable dielectric fluid

Solid state transformers (SSTs) are at the forefront of emerging technologies, enhancing distribution and transmission networks. These transformers facilitate the development of highly controllable and robust smart grids, seamlessly integrating renewable energy sources and accommodating connections for both alternating current and direct current components/lines at medium or low voltage levels. This research paper introduces an innovative SST incorporating the inductive power transfer (IPT) technology, currently under development within SSTAR, a Horizon Europe project. This novel device operates at a frequency of 50 kHz and provides with an output power of 50 kW. The IPT system is submerged in an ester-based, biodegradable dielectric fluid, providing effective cooling and insulation characteristics. The primary focus of this research is to highlight the guidelines for the optimal design of the forced liquid cooling system of the SST module. The analysis employs a multi-faceted simulation strategy to calculate the cooling aspects of the transformer, utilizing the commercial software ANSYS. This involves 3D coupled Electromagnetic (EMAG) - Computational Fluid Dynamics (CFD) simulations, as well as stand-alone CFD and thermal FEA simulations, ensuring robust cross-verification of the obtained results. This novel SST exhibits improved thermal performance, achieving a hot-spot temperature of 58 °C, the lowest value found in similar research studies. The findings underscore the efficiency and robustness of the proposed design, marking a significant step towards the realization of active and environmentally-friendly electrical networks.

Ballistic Energy Transport via Long Alkyl Chains: A New Initiation Mechanism.

In an effort to increase the speed and efficiency of ballistic energy transport via oligomeric chains, we performed measurements of the transport in compounds featuring long alkyl chains of up to 37 methylene units. Compounds of the N3-(CH2)n-COOMe type (denoted as aznME) were synthesized with n = 5, 10, 15, 19, 28, 37 and studied using relaxation-assisted two-dimensional infrared spectroscopy. The speed of the ballistic transport, initiated by the N3 tag excitation, increased ca. 3-fold for the longer chains (n = 19-37) compared to the shorter chains, from 14.7 to 48 Å/ps, in line with an earlier prediction (Nawagamuwage et al. 2021, J. Phys. Chem. B, 125, 7546). Modeling, based on solving numerically the Liouville equation, was capable of reproducing the experimental data only if three wavepackets are included, involving CH2 twisting (Tw), wagging (W), and rocking (Ro) chain bands. The approaches for designing molecular systems featuring a higher speed and efficiency of energy transport are discussed.

Adapting high-speed indentation mapping for investigating microstructure-property correlations in chromium carbide-nickel alloy coatings: Challenges and solutions

This study investigates the microstructural and mechanical characteristics of chromium carbide‑nickel rich alloy coatings produced through laser cladding, detonation spraying, and plasma spraying techniques. While all three processing techniques used the same feedstock powder, each method yields coatings with unique microstructures encompassing varying compositions and length scales. Employing Field Emission Scanning Electron Microscopy (FE-SEM) in combination with Energy Dispersive Spectroscopy (EDS) and nanoindentation mapping, local microstructure and mechanical properties were assessed at the micrometre length scale. Laser-clad coatings exhibit a typical metal matrix composite microstructure with high carbide content, distinct (MoNb)C2 phases, and Fe in the metallic matrix, while the thermal sprayed coatings showed carbides of varying sizes and metallic matrix with varying degrees of chromium dissolved in it. The instrumented indentation technique helped precisely record the microstructural features in all the coatings. Chromium carbide consistently emerges as the hardest phase across all coatings, with variations in metallic matrix hardness. Higher matrix hardness in thermal sprayed coatings correlates with increased Cr content, attributed to extended solid solubility of Cr and the presence of Mo and Nb. Energy dispersive spectroscopy and transmission electron microscopy provided clearer insight into the microstructure. This study highlights a direct one-to-one correlation between microstructure and mechanical properties mapped using instrumented indentation techniques in chromium carbide‑nickel rich coatings across different deposition methods.

Force-free Wave Interaction in Magnetar Magnetospheres: Computational Modeling in Axisymmetry

Crustal quakes of highly magnetized neutron stars can disrupt their magnetospheres, triggering energetic phenomena like X-ray and fast radio bursts. Understanding plasma wave dynamics in these extreme environments is vital for predicting energy transport across scales to the radiation length. This study models relativistic plasma wave interaction in magnetar magnetospheres with force-free electrodynamics simulations. For propagation along curved magnetic field lines, we observe the continuous conversion of Alfvén waves to fast magnetosonic (FMS) waves. The conversion efficiency can be up to three times higher when counter-propagating Alfvén waves interact in the equatorial region. Alfvén waves generate FMS waves of twice their frequency during their first crossing of the magnetosphere. After the initial transient burst of FMS waves, Alfvén waves convert to FMS waves periodically, generating variations on timescales of the magnetospheric Alfvén wave crossing time. This decaying FMS wave tail carries a significant portion (half) of the total energy emitted. Plastic damping of “bouncing” Alfvén waves by the magnetar crust has minimal impact on the FMS efficiency. We discuss the implications of the identified wave phenomena for magnetar observations. Outgoing FMS waves can develop electric zones, potential sources of coherent radiation. Long wavelength FMS waves could generate FRBs through reconnection beyond the light cylinder.

Converter-based multi-frequency power transfer system for efficient energy packet transmission in the energy internet

The energy internet concept involves the transmission of energy in discrete packets, akin to the information internet's principle. The energy internet must adopt a decentralized configuration and enable bidirectional and simultaneous power transfer. This raises the problem of congestions during the energy packet dispatching process. To address potential congestion issues, we propose a three-phase multi-frequency power transfer system (MFPTS) where the positive-sequence fundamental frequency component is supplemented with the zero-sequence third and the negative-sequence fifth harmonic components. By using such signals with proper amplitudes, the harmonics are added to the voltage without changing the peak amplitude but increasing the rms value. To exert complete control over the different frequencies employed within the MFPTS, a decoupling method is necessary to separate these frequencies in the control system. This leads to creating three independent channels of power transfer by three frequencies without changing the existing infrastructure as these powers can be transferred within the same lines. This paper explores the feasibility of three-phase three-frequency power transfer by using three parallel power transfer channels, achieved through the utilization of three-phase grid-forming and grid-feeding converters. Using power converters provides the advantage of bidirectional power transfer and facilitates decentralization by serving as an interface between distributed power generation systems and the utility grid. These properties are essential for achieving optimal energy internet performance. The simulation and practical results prove that the proposed MFPTS could solve the energy packet dispatching congestion problem to have a reliable energy internet for the future.

Universal Bound on Effective Central Charge and Its Saturation

The effective central charge (denoted by ceff) is a measure of entanglement through a conformal interface, while the transmission coefficient (encoded in the coefficient cLR of the two-point function of the energy-momentum tensor across the interface) is a measure of energy transmission through the interface. It has been pointed out that these two are generally different. In this Letter, we propose the inequalities, 0≤cLR≤ceff≤min(cL,cR). They have the simple but important implication that the amount of energy transmission can never exceed the amount of information transmission. We verify them using the AdS/CFT correspondence, using the perturbation method, and in examples beyond holography. We also show that these inequalities are sharp by constructing a class of interfaces that saturate them. Published by the American Physical Society 2024

Establishing patterns of change in the coefficients of reflection, transmission, and dissipation of wave energy depending on parameters of a permeable vertical wall

The object of research is permeable vertical walls (breakwaters) with different degrees of permeability. This paper reports the results of experimental research into the interaction of gravity waves with models of permeable vertical walls (breakwaters), which were formed from cylindrical piles of circular cross-section. With the help of visual and instrumental studies, the features of interaction of surface gravity waves with permeable vertical walls of different permeability have been identified. The degree of wave transformation by these walls was also determined in the form of reflection, transmission, and dissipation coefficients of wave energy. It was established that with a decrease in the permeability of the vertical wall and an increase in the steepness of the initial wave and a decrease in its period, the height of the reflected wave increased. The pattern of the transmitted wave height had the opposite trend. It was determined that the wave reflection coefficient increased with a decrease in the permeability of the vertical wall and the steepness of the initial wave. The wave transmission coefficient had the opposite trend, namely, it increased with increasing wall permeability and with decreasing steepness of the initial wave. The gravity wave energy dissipation coefficient decreased with increasing vertical wall permeability, but for waves with a significant steepness hi/λ>0.038, a decrease in the wave energy dissipation coefficient was observed for walls with low permeability and the appearance of extreme values of this coefficient. Thus, features in the interaction of surface gravity waves with permeable vertical walls (breakwaters) of different permeability have been researched and the degree of wave transformation by these walls has been determined, which could make it possible to effectively design and operate permeable vertical walls as coastal protection structures

Shoaling Internal Tides Propagating From a Shallow Ridge Modulated by the Kuroshio

AbstractThis study presents remotely generated internal tides that propagate into shallow regions and are modulated by background flows using numerical simulations and field observation data. Numerical results indicate that strongly enhanced semi‐diurnal (∼M2) internal tide energy is generated over a shallow ridge, the Izu‐Ogasawara Ridge. The generated internal tides propagates toward the Kuroshio upstream and shoal toward shallow regions near Cape Shiono‐Misaki. The intensified internal tide energy flux toward the cape is explained by two mechanisms: (a) intensified internal tide generation over the ridge due to the interaction between tides and the Kuroshio and (b) wave energy convergence along the Kuroshio due to wave refractions. A 13‐year field data set obtained from the cape was used to investigate shoaling internal tides influenced by the Kuroshio. The observed results reveal a significant positive correlation between the kinetic energy of semi‐diurnal internal tides and the background flows caused by the Kuroshio, which evidently supports the intensified internal tides attributed to the interaction between background flows and tides, as proposed by recent studies. The intensity of shoaling internal tides is also largely influenced by the path of the Kuroshio and seasonal effects. The magnitude of shoaling internal tides is clearly weaken as the Kuroshio meander occurs. Shoaling internal tides modulated by the Kuroshio can provide new insights into energy transport and mixing processes in coastal oceans.

Thermal Energy Transport through Nonbonded Native Contacts in Protein.

Within the protein interior, where we observe various types of interactions, nonuniform flow of thermal energy occurs along the polypeptide chain and through nonbonded native contacts, leading to inhomogeneous transport efficiencies from one site to another. The folded native protein serves not merely as thermal transfer medium but, more importantly, as sophisticated molecular nanomachines in cells. Therefore, we are particularly interested in what sort of "communication" is mediated through native contacts in the folded proteins and how such features are quantitatively depicted in terms of local transport coefficients of heat currents. To address the issue, we introduced a concept of inter-residue thermal conductivity and characterized the nonuniform thermal transport properties of a small globular protein, HP36, using equilibrium molecular dynamics simulation and the Green-Kubo formula. We observed that the thermal transport of the protein was dominated by that along the polypeptide chain, while the local thermal conductivity of nonbonded native contacts decreased in the order of H-bonding > π-stacking > electrostatic > hydrophobic contacts. Furthermore, we applied machine learning techniques to analyze the molecular mechanism of protein thermal transport. As a result, the contact distance, variance in contact distance, and H-bonding occurrence probability during MD simulations are found to be the top three important determinants for predicting local thermal transport coefficients.

Nuclear acoustic envelope soliton in a relativistically degenerate magneto-rotating stellar plasma

The study explores a model called Relativistic Degenerate Magneto-Rotating Quantum Plasma (RDMRQP), which comprises a static heavy nucleus, an inertial non-degenerate light nucleus, and warm non-relativistic or ultra-relativistic electrons. The focus is on observing the emergence of Nucleus-Acoustic Envelope Solitons (NAESs). Using the reductive perturbation method, a Nonlinear Schrödinger equation (NLSE) is derived to characterize the properties of NAESs. We have analysed the Peregrine breather soliton solution. The investigation reveals that the temperature of warm degenerate species, plasma system’s rotational speed, and the presence of heavy nucleus species can alter the fundamental features (height and width) of NAESs in the WDMRQP system. The study emphasizes the existence of only positive NA wave potential. Additionally, a phase plane analysis is conducted to gain a deeper understanding of the parametric dependencies. Through detailed mathematical and numerical analysis, the study avoids overloading with complex mathematics while demonstrating parametric dependence via phase portrait analysis. The research augments the envelop soliton model with breather mode solutions and discusses modulation instability using the Benjamin-Feir Index, highlighting the significance of solitons in star formation. Envelop solitons, stable waves within stars and proto-stars, influence energy transport and stellar evolution, playing a crucial role in the accretion process and formation of stable structures. Key findings include the effects of various parameters on NAESs’ generation and propagation in which non-relativistic and ultra-relativistic electrons support NAESs, with amplitude and width influenced by temperature, rotational frequency, inclination angle, and the presence of a static heavy nucleus. The research is applicable to hot white dwarfs and neutron stars, suggesting further exploration of quantum effects and non-planar or arbitrary amplitude NAESs.

Technology Selection of High-Voltage Offshore Substations Based on Artificial Intelligence

This paper proposes an automated approach to the technology selection of High-Voltage Alternating Current (HVAC) Offshore Substations (OHVS) for the integration of Oil & Gas (O&G) production and Offshore Wind Farms (OWF) based on Artificial Intelligence (AI) techniques. Due to the complex regulatory landscape and project diversity, this is enacted via a cost decision-model which was developed based on Knowledge-Based Systems (KBS) and incorporated into an optioneering software named Transmission Optioneering Model (TOM). Equipped with an interactive dashboard, it uses detailed transmission and cost models, as well as a technological and commercial benchmarking of offshore projects to provide a standardized selection approach to OHVS design. By automating this process, the deployment of a technically sound and cost-effective connection in an interactive sandbox environment is streamlined. The decision-model takes as primary inputs the power rating requirements and the distance of the offshore target site and tests multiple voltage/rating configurations and associated costs. The output is then the most technically and economically efficient interconnection setup. Since the TOM process relies on equivalent models and on a broad range of different projects, it is manufacturer-agnostic and can be used for virtually any site as a method that ensures both energy transmission and economic efficiency.

Occurrence of Kelvin–Helmholtz Instability at Lunar Distance Magnetopause: ARTEMIS Observation

Kelvin–Helmholtz waves can be observed frequently at the near-Earth magnetopause and play an important role in the transport of particles, momentum, and energy from the solar wind to the magnetosphere. This work analyzes the occurrence of Kelvin–Helmholtz instability (KHI) at lunar distance magnetopause, which has not been thoroughly studied currently based on Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun satellite observations, and it also investigates the effect of the upstream solar wind and interplanetary magnetic field (IMF). Statistical results show that (1) the occurrence rate is about 15% of the time at lunar distance, lower than at the flank magnetopause, and (2) the occurrence rate decreases with the magnetoacoustic Mach number, Alfvén Mach number, solar wind velocity, and dynamic pressure but only shows a slightly positive correlation with solar wind density. Unlike at the dayside magnetopause, the occurrence rate of KHI diminishes as the solar wind velocity increases at the lunar distance magnetopause, and (3) the occurrence rate decreases with IMF amplitude and is influenced by IMF orientation. As a function of the IMF clock angle, the occurrence rate reaches its maximum at ∼24% when the clock angle is zero. The statistical results are basically consistent with the currently accepted linear theory of KHI, except for a lower rate for higher-speed solar wind. This work contributes to understanding the excitation and evolution of KHI along the magnetopause and plasma transport process in the tail magnetopause.

Boosting peroxymonosulfate activation via Fe–Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe–Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M−1‧min−1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

A hybrid intelligent system for protection of transmission lines connected to PV farms based on linear trends

Conventional relays face challenges for transmission lines connected to inverter-based resources (IBRs). In this article, a single-ended intelligent protection of the transmission line in the zone between the grid and the PV farm is suggested. The method employs a fuzzy logic and random forest (RF)-based hybrid system to detect faults based on combined linear trend attributes of the 3-phase currents. The fault location is determined and the faulty phase is detected. RF feature selection is used to obtain the optimal linear trend feature. The performance of the methodology is examined for abnormal events such as faults, capacitor and load-switching operations simulated in PSCAD/EMTDC on IEEE 9-bus system obtained by varying various fault and switching parameters. Additionally, when validating the suggested strategy, consideration is given to the effects of conditions such as the presence of double circuit lines, PV capacity, sampling rate, data window length, noise, high impedance faults, CT saturation, compensation devices, evolving and cross-country faults, and far-end and near-end faults. The findings indicate that the suggested strategy can be used to deal with a variety of system configurations and situations while still safeguarding such complex power transmission networks.

Three-dimensional thermal-electrochemical-hydrodynamic numerical study of vanadium redox flow battery with different flow fields and non-homogeneously compressed electrode

This paper presents a concise 3D numerical study of Vanadium Redox Flow Batteries (VRFBs) with different flow field designs and non-homogeneously compressed electrodes. The model integrates mass, momentum, charge, and energy transport equations, including reaction kinetics for vanadium species. Four flow field designs (conventional, parallel, serpentine, and interdigitated) are evaluated for heat distribution uniformity. The model accounts for non-uniform electrode properties due to compression. Numerical results are validated against experimental data, exploring the impact of operating parameters such as current density, flow rate, and temperature on thermal behavior. The study also compares heat generated by electrochemical reactions, ohmic losses, and chemical activation across different flow fields. The findings revealed the highest temperature gradient and non-uniformity (in terms of temperature) with conventional designs followed by interdigitated, parallel and serpentine. Importantly, the study consistently highlights elevated temperatures in the discharge condition across all configurations. This emphasizes the need for precise temperature control to prevent VO₂+ precipitation. These insights from VRFB optimization efforts are thoroughly presented in this paper.