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Gilbert damping is a key parameter representing the energy loss in the Landau–Lifshitz–Gilbert equation, which describes the dynamics of magnetization and is crucial in micromagnetic simulations. We have developed an analytical method to calculate Gilbert damping based on the contributions from the three-particle magnon scattering process. By incorporating the exchange, anisotropic, and demagnetization energies, we applied this method to determine Gilbert damping at different temperatures. Our calculation shows that, near the Curie temperature, the calculated damping equals around 80% of the results obtained from the coarse-graining method proposed by Feng and Visscher in 2001, which means that three-magnon scattering gives a dominant contribution to Gilbert damping. This research may give useful insights into the relationship between Gilbert damping and magnons. [ABSTRACT FROM AUTHOR]

The current research investigates the potential advantages of optimally combining wide bandgap Al2O3 with high dielectric constant (high-κ) Ta2O5 for gate dielectric applications. Various compositions of 10 nm AlxTayO oxide films are grown on the Al0.3Ga0.7N/GaN heterostructure by co-sputtering Al and Ta metals, followed by thermal oxidation at 500 °C. The average root-mean-square roughness of the grown oxide films is ∼1.2–1.4 nm compared to 0.4 nm for as-deposited metal. X-ray photoelectron spectroscopy and transmission electron microscopyconfirm the formation and thickness of the grown oxide films. The bandgap (E g) of the oxide films calculated from O 1 s electron energy loss spectra show a linear increase from 4.85 eV for pure Ta2O5 to 6.4 eV for pure Al2O3. The dielectric constant (ε ox ) calculated from capacitance–voltage (C G − V G) measurements decreases linearly from 25.7 for Ta2O5 to 7.9 for Al2O3. The interface trap density (D it ) is estimated from the frequency dispersion of capacitance–voltage (C G − V G) characteristics. The DC and radio frequency (RF) characteristics of AlxTayO/Al0.3Ga0.7N/GaN high electron mobility transistor (HEMT) devices are measured and compared with the Schottky HEMT devices (without any gate oxide). Compared to Schottky HEMT devices, AlxTayO/Al0.3Ga0.7N/GaN HEMT devices show superior DC characteristics, which helps us achieve maximum RF output power. Furthermore, the OFF-state measurements show that the AlxTayO/Al0.3Ga0.7N/GaN HEMT devices can sustain higher source-to-drain voltages, from a minimum of 88 V on pure Ta2O5 metal-oxide-semiconductor (MOS)-HEMTs to a maximum of 138 V on pure Al2O3 MOS-HEMTs before the dielectric breakdown happens, compared to a 57 V breakdown voltage on Schottky HEMT devices. An oxide variation of AlxTayO, with Al composition ratio of 0.34, shows an exceptional ION/IOFF ratio of 4 × 1011, a gate leakage current of 8 × 10−12 A/mm, a near-ideal subthreshold slope of 63.8 mV/dec, and the unity current gain frequency ( f T) of 25.6 GHz. [ABSTRACT FROM AUTHOR]

We report the effect of thickness and width on the spin wave transport and dispersion characteristics of permalloy (Py) microstripes using analytical calculations and experiments. Py waveguides with widths ranging from 2 to 4 μm were fabricated for two different thicknesses: 5 and 20 nm. Our results show a notable increase in the group velocity of spin waves with greater thickness, showing a fourfold rise as the thickness increases. Additionally, the accessible frequency range expands from 0.6 to 2.5 GHz as the thickness increases. We find that the spin wave mode frequency is affected by both thickness and width, with a frequency shift of approximately 0.2 GHz observed when the width increases from 2 to 4 μm. Moreover, spin waves decay more rapidly in thinner films, with the decay length of 20 nm-thick waveguides being four times longer than that of 5 nm-thick waveguides. Thicker and wider waveguides provide a longer decay length, facilitating the transmission of information over longer distances without significant energy loss. Our study offers an understanding of the spin wave propagation in microstrip waveguides and its potential in the development of future magnonic devices. [ABSTRACT FROM AUTHOR]

It has been supposed that the interplay of elasticity and activity plays a key role in triggering the non-equilibrium behaviors in biological systems. However, the experimental model system is missing to investigate the spatiotemporally dynamical phenomena. Here, a model system of an active chain, where active eccentric-disks are linked by a spring, is designed to study the interplay of activity, elasticity, and friction. Individual active chain exhibits longitudinal and transverse motions; however, it starts to self-rotate when pinning one end and self-beat when clamping one end. In addition, our eccentric-disk model can qualitatively reproduce such behaviors and explain the unusual self-rotation of the first disk around its geometric center. Furthermore, the structure and dynamics of long chains were studied via simulations without steric interactions. It was found that a hairpin conformation emerges in free motion, while in the constrained motions, the rotational and beating frequencies scale with the flexure number (the ratio of self-propelling force to bending rigidity), χ, as ∼(χ)4/3. Scaling analysis suggests that it results from the balance between activity and energy dissipation. Our findings show that topological constraints play a vital role in non-equilibrium synergy behaviors. [ABSTRACT FROM AUTHOR]

Exploring the plasmon energy dissipation mechanism of bimetallic nanostructures after photoexcitation is of great significance for controlling energy transfer in plasmonic applications. The absorption, scattering, and extinction spectra of Ag@Cu, Ag@Pt, and Ag@Co core–shell nanostructures are calculated by finite element method, and the energy dissipation process is visualized by using particle trajectory and the absorbed power density distribution. The absorption/scattering ratio of the core–shell nanostructures, the shell absorptivity, the time-domain electric field as well as the extra-core electron arrangements of Ag, Cu, Pt, and Co atoms are analyzed for figuring out the energy dissipation mechanism. The results show that when a non-plasmonic metal is coated on the surface of a plasmonic metal, the plasmon energy dissipates preferentially in the shell, and the degree of dissipation depends on the imaginary part of the dielectric constant of the shell and the core. A larger dielectric constant of the shell can cause more energy to be transferred from the plasmonic metal to the shell region. This study provides the fundamental physical framework and design principles for plasmonic nanostructures. [ABSTRACT FROM AUTHOR]

Strain engineering using ion beams is a current topic of research interest in semiconductor materials. Synchrotron-based high-resolution x-ray diffraction has been utilized for strain-depth analysis in GaAs irradiated with 300 keV Ar and 4H-SiC and GaAs irradiated with 100 MeV Ag ions. The direct displacement-related defect formation, anticipated from the elastic energy loss of Ar ions, can well explain the irradiation-induced strain depth profiles. The maximum strain in GaAs is evaluated to be 0.88% after Ar irradiation. The unique energy loss depth profile of 100 MeV Ag (swift heavy ions; SHIs) and resistance of pristine 4H-SiC and GaAs to form amorphous/highly disordered ion tracks by ionization energy loss of monatomic ions allow us to examine strain buildup due to the concentrated displacement damage by the elastic energy loss near the end of ion range (∼ 12 μ m). Interestingly, for the case of SHIs, the strain-depth evolution requires consideration of recovery by ionization energy loss component in addition to the elastic displacement damage. For GaAs, strain builds up throughout the ion range, and the maximum strain increases and then saturates at 0.37% above an ion fluence of 3 × 10 13 Ag/cm 2. For 4H-SiC, the maximum strain reaches 4.6% and then starts to recover for fluences above 1 × 10 13 Ag/cm 2. Finally, the contribution of irradiation defects and the purely mechanical contribution to the total strain have been considered to understand the response of different compounds to ion irradiation. [ABSTRACT FROM AUTHOR]

This paper addresses the challenge of efficiently designing multiplexer structures in quantum-dot technology circuits. Specifically, it introduces a novel approach to constructing a 2-to-1 multiplexer through a unique gate design that relies on the interaction between cells. The key focus of this design is to minimize the utilization of cells, thereby conserving space and facilitating the creation of more complex combinational and sequential circuits. The methodology involves developing a gate structure that requires the least number of cells compared to existing designs. This reduction in cell usage not only optimizes space utilization but also enhances the scalability of the multiplexer for integration into larger circuits. The proposed gate structure demonstrates a significant improvement, achieving a 15% reduction in the number of cells compared to the previously best-known design. To further evaluate the effectiveness of this novel gate design, the study extends its analysis to include the implementation of various complex circuits such as a 4-to-1 multiplexer, D latch, and T latch. These structures are synthesized using the newly proposed gate design as a fundamental building block. To validate the functionality and performance of these circuits, simulations are conducted using the QCADesigner simulation tool. This comprehensive simulation enables a thorough assessment of the proposed structures across different circuit configurations, providing insights into their operational efficiency and suitability for practical applications in quantum-dot technology. [ABSTRACT FROM AUTHOR]

The influence of argon and helium on the rovibrational kinetics of carbon dioxide (CO2) and CO in low-temperature conversion plasma is investigated. With this objective, a combined experimental and computational study is conducted, applying quantum cascade laser infrared absorption spectroscopy to a pulsed DC CO2 glow discharge with varying noble gas admixture and modeling it with a two-term Boltzmann solver. Time-resolved rovibrational temperatures and dissociation fractions are presented, exhibiting an increase in rotational–vibrational non-equilibrium and an increasing CO2 conversion with argon (Ar) and helium (He) admixtures. Results are discussed in the context of energy transfer processes for collisions involving electrons, corroborated by electron-kinetic modeling, and heavy particle collisions. With noble gas addition, an increase in the electron number density, promoting excitation, and the high-energy tail of the electron energy distribution function are found. Penning ionization processes are proposed as an explanation for the increase in conversion, showing higher conversion for Ar due to the lower excitation thresholds and, therefore, larger state population. In the context of rovibrational kinetics, processes leading to the gain or loss of vibrational energy of CO2 are analyzed, pointing out subtle differences in, for example, relaxation rate coefficients between Ar and He. However, the cooling of the gas through conductive heat transfer is identified as the most important influence of the Ar and He admixture, as it keeps the relaxation rate for vibrational quenching low. [ABSTRACT FROM AUTHOR]

A new class of acoustic black hole (ABH) waveguides is presented, which relies in its operation on an array of optimally designed functionally graded perforated rings (FGPRs). In this manner, the developed ABH is provided with built-in energy dissipation characteristics generated by virtue of the flow through perforations, which enhances its acoustic absorption behavior and makes the speed of the propagating waves vanish faster when reaching the end of the waveguide. Furthermore, the particular design of the rings enables sandwiching of additional porous absorbing layers between the rings to further boost the absorption characteristics of the proposed ABH. Accordingly, the operating principle of the new class of ABH is radically different from that of the conventional ABH that employs sequential solid-flat rings of decreasing inner radii to create a virtual power law taper necessary for generating the black hole effect, but through reactive means rather than the effective dissipative means of the proposed ABH. Therefore, this paper develops a transfer matrix modeling (TMM) approach to model the absorption and reflection characteristics of the new class of ABH, in an attempt to predict its behavior, optimize the selection of its design parameters, and more importantly, demonstrate its merits as effective means for controlling sound propagation. Numerical examples are presented to highlight the merits and behavior of the proposed ABH. Predictions of the TMM are validated against experimental results that are available in the literature for one and two micro-perforated plates. Comparisons are also established between the ABH with FGPR and the conventional ABH in order to distinguish the behavior and underlying principles of their operations. [ABSTRACT FROM AUTHOR]

We have calculated electron backscattering coefficients, η (E p) , at primary electron energies E p of 0.1–100 keV for three elemental and intermediate atomic number solids, Cr, Co and Pd, with an up-to-date Monte Carlo simulation model. A relativistic dielectric functional approach is adopted for the calculation of the electron inelastic cross section, where several different datasets of optical energy loss function (ELF) are adopted. The calculated backscattering coefficient is found to be substantially affected by the ELF, where the influence can be seen to follow the f- and ps-sum rules and the resultant energy dependence of electron inelastic mean free path. To understand the uncertainties involved in a comparison with experimental data both the theoretical uncertainty due to the elastic cross-section model and the experimental systematic error for the contaminated surfaces are investigated. A total of 192 different scattering potentials are employed for the calculation of Mott's electron elastic cross section and this theoretical uncertainty is confirmed to be small. On the other hand, the simulation of contaminated Co and Pd surfaces with several carbonaceous atomic layers can well explain the experimental data. The present results indicate that accurate backscattering coefficient data should be either measured from fully cleaned surfaces or obtained from modern Monte Carlo theoretical calculations involving reliable optical constants data. With the recent progress in the accurate measurement of optical constants by reflection electron energy loss spectroscopy technique, constructing a reliable theoretical database of electron backscattering coefficients for clean surfaces of elemental solids is highly hopeful. [ABSTRACT FROM AUTHOR]

Ultra-thin solar cells display high intrinsic radiation tolerance, making them interesting for space applications. This study investigates the dependence of the open-circuit voltage degradation and overall current–voltage behavior of devices with 80 nm thick GaAs absorber layers, on their absorber layer doping concentration and the radiation type used to introduce damage. The radiation types used were 1 MeV electrons and 20 keV, 100 keV, and 1 MeV protons. It is shown that the open-circuit voltage degradation rate increases with absorber layer doping concentration. This is linked to the increase in trap-assisted tunneling enhancement of the recombination rate, facilitated by the increase in electric field strength in the absorber layer with doping concentration. Trap-assisted tunneling is also found to contribute to the high local ideality factors observed in these devices, exceeding values of 2, and to be responsible for the trend of an increasing ideality factor with doping concentration. The significant role of trap-assisted tunneling in the devices is established through fitting of dark current–voltage data using a custom recombination–generation model. An open-circuit voltage degradation rate and local ideality factor curves are also shown to vary with radiation type, despite accounting for their differences in non-ionizing energy loss. This is corroborated by corresponding trends in carrier lifetime damage constants, extracted from the fitting of the dark current–voltage curves. This suggests that the introduction or behavior of radiation damage differs between ultra-thin and conventional, thicker solar cells, where non-ionizing energy loss theory tends to be reliable, especially over the studied proton energy range. [ABSTRACT FROM AUTHOR]

In the previous paper [C. W. Kim and I. Franco, J. Chem. Phys. 160, 214111-1–214111-13 (2024)], we developed a theory called MQME-D, which allows us to decompose the overall energy dissipation process in open quantum system dynamics into contributions by individual components of the bath when the subsystem dynamics is governed by a Markovian quantum master equation (MQME). Here, we contrast the predictions of MQME-D against the numerically exact results obtained by combining hierarchical equations of motion (HEOM) with a recently reported protocol for monitoring the statistics of the bath. Overall, MQME-D accurately captures the contributions of specific bath components to the overall dissipation while greatly reducing the computational cost compared to exact computations using HEOM. The computations show that MQME-D exhibits errors originating from its inherent Markov approximation. We demonstrate that its accuracy can be significantly increased by incorporating non-Markovianity by exploiting time scale separations (TSS) in different components of the bath. Our work demonstrates that MQME-D combined with TSS can be reliably used to understand how energy is dissipated in realistic open quantum system dynamics. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) thin films offer advantages in microelectromechanical systems (MEMSs) including large motion, lower drive voltage, and high energy densities. Depending on the application, different substrates are sometimes required. Self-heating occurs in the PZT MEMS due to the energy loss from domain wall motion, which can degrade the device performance and reliability. In this work, the self-heating of PZT thin films on Si and glass and a film released from a substrate were investigated to understand the effect of substrates on the device temperature rise. Nano-particle assisted Raman thermometry was employed to quantify the operational temperature rise of these PZT actuators. The results were validated using a finite element thermal model, where the volumetric heat generation was experimentally determined from the hysteresis loss. While the volumetric heat generation of the PZT films on different substrates was similar, the PZT films on the Si substrate showed a minimal temperature rise due to the effective heat dissipation through the high thermal conductivity substrate. The temperature rise on the released structure is 6.8× higher than that on the glass substrates due to the absence of vertical heat dissipation. The experimental and modeling results show that the thin layer of residual Si remaining after etching plays a crucial role in mitigating the effect of device self-heating. The outcomes of this study suggest that high thermal conductivity passive elastic layers can be used as an effective thermal management solution for PZT-based MEMS actuators. [ABSTRACT FROM AUTHOR]

We study a moving adsorbate interacting with a metal electrode immersed in a solvent using the time-dependent Newns–Anderson–Schmickler model Hamiltonian. We have adopted a semiclassical trajectory treatment of the adsorbate to discuss the electron and energy transfers that occur between the adsorbate and the electrode. Using Keldysh Green's function scheme, we found a non-adiabatically suppressed electron transfer caused by the motion of the adsorbate and coupling with bath phonons that model the solvent. The energy is thus dissipated into electron–hole pair excitations, which are hindered by interacting with the solvent modes and facilitated by the applied electrode potential. The average energy transfer rate is discussed in terms of the electron friction coefficient and given an analytical expression in the slow-motion limit. [ABSTRACT FROM AUTHOR]

The rates and pathways of chemical reactions at metal surfaces can be strongly influenced by energy dissipation due to the nonadiabatic excitation of metallic conduction electrons. The introduction of frictional forces to account for this dissipation has been quite successful in situations for which the nonadiabatic coupling is weak. However, in cases where nonadiabatic coupling is strong, such as when electron transfer occurs, the friction model is likely to break down. Ryabinkin and Izmaylov have proposed 2-state and 3-state alternatives to the friction model for introducing electronic dissipation in molecular dynamics simulations. Here, we examine their 2-state model using some simple examples of atom–surface scattering. We find that, with the addition of decoherence, the 2-state model can produce quite promising results. [ABSTRACT FROM AUTHOR]

The reversible quantum-flux-parametron (RQFP) is a reversible logic gate based on an energy-efficient superconductor logic family, namely, the adiabatic quantum-flux-parametron logic. The RQFP can perform logic operations in a thermodynamically reversible manner (i.e., without energy dissipation) in the quasi-static limit due to its logical and physical reversibility. Hence, it can be used for investigating the fundamental relations between information and thermodynamics from a circuit perspective. In the present study, we propose a reversible flip-flop (RFF) comprising an RQFP and investigate the minimum energy dissipation required for general information processing through numerical simulation using an RFF-based circuit. This circuit includes fundamental information processing (combinational logic, sequential logic, and data erasure) and can, thus, be used as a physical model for such an investigation. The numerical simulation of this circuit shows that both combinational and sequential logic operations can be conducted without energy dissipation in the quasi-static limit and that the amount of erased data determines the minimum energy dissipation. These results indicate that general information processing can be conducted in a thermodynamically reversible manner by using RQFP circuits as long as all data, including garbage outputs, are conserved. [ABSTRACT FROM AUTHOR]

An approach for approximating position and orientation dependent translational and rotational diffusion coefficients of rigid molecules of any shape suspended in a viscous fluid under geometric confinement is proposed. It is an extension of the previously developed scheme for evaluating near-wall diffusion of macromolecules, now applied to any geometry of boundaries. The method relies on shape based coarse-graining combined with scaling of mobility matrix components by factors derived based on energy dissipation arguments for Stokes flows. Tests performed for a capsule shaped molecule and its coarse-grained model, a dumbbell, for three different types of boundaries (a sphere, an open cylinder, and two parallel planes) are described. An almost perfect agreement between mobility functions of the detailed and coarse-grained models, even close to boundary surfaces, is obtained. The proposed method can be used to simplify hydrodynamic calculations and reduce errors introduced due to coarse-graining of molecular shapes. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals have been under intense investigation for their promise in optoelectronic devices due to their remarkable physics, such as liquid/solid duality. This liquid/solid duality may give rise to their defect tolerance and other such useful properties. This duality means that the electronic states are fluctuating in time, on a distribution of timescales from femtoseconds to picoseconds. Hence, these lattice induced energy fluctuations that are connected to polaron formation are also connected to exciton formation and dynamics. We observe these correlations and dynamics in metal halide perovskite nanocrystals of CsPbI3 and CsPbBr3 using two-dimensional electronic (2DE) spectroscopy, with its unique ability to resolve dynamics in heterogeneously broadened systems. The 2DE spectra immediately reveal a previously unobserved excitonic splitting in these 15 nm NCs that may have a coarse excitonic structure. 2D lineshape dynamics reveal a glassy response on the 300 fs timescale due to polaron formation. The lighter Br system shows larger amplitude and faster timescale fluctuations that give rise to dynamic line broadening. The 2DE signals enable 1D transient absorption analysis of exciton cooling dynamics. Exciton cooling within this doublet is shown to take place on a slower timescale than within the excitonic continuum. The energy dissipation rates are the same for the I and Br systems for incoherent exciton cooling but are very different for the coherent dynamics that give rise to line broadening. Exciton cooling is shown to take place on the same timescale as polaron formation, revealing both as coupled many-body excitation. [ABSTRACT FROM AUTHOR]

The dynamic response of dielectric elastomers is widely used in many functional devices, but current research has neglected the effect of varying dielectric permittivity on their dynamic oscillations and stability. This paper studies the thin-walled dielectric balloon in which the stretch-dependent dielectric permittivity is considered. We obtain the dynamic equation of motion by Hamilton's principle. Based on the principle of no energy dissipation in conservative systems, we establish energy conservation at the maximum stretching position and at the initial moment, then we investigate the stability in the dynamic case. It is found that a stretch-related dielectric permittivity can increase the critical electric field of the balloon and can also change the mode of electric field instability and modulate the critical stretch value. In the dynamic case, the stretch-dependent permittivity increases the critical electric field by 4 % when the balloon is only subjected to electric force; moreover, it increases the critical stretch value by 316.68 % by changing the unstable mode from pull-in instability to snap-through instability. It is hoped that this work will provide new thinking in designing functional devices by using the dynamical response and stability of dielectric elastomers. [ABSTRACT FROM AUTHOR]

This paper reports the mass and energy transmission characteristics of an electrically conducting mixed convective nanofluid flow past a stretching Riga plate. An additional effect of viscous dissipation, Arrhenius activation energy and heat source is also studied. The energy and mass transmissions are evaluated by a zero-mass flux of nanoparticle and convective boundary conditions. Buongiorno's relations are proposed for the Brownian motion and thermophoretic diffusion. The similarity substitutions are employed to derive the non-dimensional set of modeled equations. The obtained set of equations is numerically processed via parametric continuation method (PCM). Several flow factors affecting the velocity, energy, and mass distributions are graphically discussed. It has been perceived that the fluid velocity field declines with the influence of velocity power index (m), while improves with the upshot of modified Hartmann number (Q). The effect of Schmidt number and chemical reaction diminishes the concentration profile φ (η). Furthermore, the energy curve enhances with the effect of thermophoresis factor, Biot and Eckert number. [ABSTRACT FROM AUTHOR]

Scientists devote their time and energy to studying and developing hydrogen storage devices to address the energy crisis and climate change. Because of this, investigations are conducted to reveal the optoelectronic, structural, bader charge, electronic charge density, and hydrogen storage properties of X 2 LiAlH 6 (X = K, Mn) within the framework of density functional theory, and calculations of the structural characteristics were carried out utilizing local and nonlocal, and hybrid functionals. An additional onsite Coulomb parameter (GGA + U), which includes the Hubbard parameter, was used to apply the potential. Calculations based on the Kramer-Kroning principle were used to determine the dielectric function, refractive index, extinction coefficient, and energy loss function. The results indicate that K 2 LiAlH 6 and Mn 2 LiAlH 6 are highly suitable for hydrogen storage applications. The gravimetric ratios of hydrogen storage capacities for both investigated materials are 5.2 wt %, and 7.5 wt %, respectively. The interaction of the Mn-d, Li-s, K-s, and H-s/p orbitals was the cause of hybridization, according to the optoelectronic characteristics. Compound stability is indicated by the negative computed formation energy of the materials under investigation. The electronic charge density analysis showed a mixed-bond semiconductor with low ionicity and high covalence. In addition, the radiation shielding properties of Mn 2 LiAlH 6 and K 2 LiAlH 6 were investigated using Phy-X software, showing promising results in linear attenuation, half-value layer, and mean free path, particularly for Mn 2 LiAlH 6 due to its higher atomic number. This groundbreaking study represents a pioneering computational exploration of X 2 LiAlH 6 , offering promising advancements for future research in hydrogen storage applications. • The structural properties of X 2 LiAlH 6 were analyzed using DFT, revealing promising stability metrics. • Mn 2 LiAlH 6 shows enhanced radiation shielding due to its higher atomic number and interaction effects. • Hydrogen storage capacity for K 2 LiAlH 6 and Mn2LiAlH6 was calculated to be 5.2 wt % and 4.7 wt %, respectively. • Phy-X software simulations revealed Mn 2 LiAlH 6 's superior shielding performance against gamma rays. • Optical properties demonstrated high absorption coefficients, indicating potential for energy applications. [ABSTRACT FROM AUTHOR]

R2Mx is a new receiver-reactor concept for solar thermochemical water splitting cycles. The main difference to the current state-of-the-art is the use of a continuously operated reduction reactor with multiple mobile redox units. A plant model is developed for a version of the R2Mx concept with surrounding heliostat fields at MW scale. Performance estimates are derived over a large parameter space to characterize the plant and to identify possible technical challenges as well as research needs. Even without solid-solid heat recovery, the model predicts average annual plant efficiencies of up to 10.5% for multi MW receiver-reactors, which is comparable to commercial solutions. Furthermore, about 28% of the total energy input are energy losses occurring as highly concentrated radiation or as high temperature heat, emphasizing the improvement potential of the technology. Realizing the described enhancement options can turn this concept into an economic, large-scale fuel production technology. • The receiver-reactor R2Mx with surrounding heliostat fields is introduced and a comprehensive plant model is presented. • The performance of the complete solar thermochemical plant at MW scale was calculated for 432,000 parameter sets. • Different metrics are evaluated to characterize the plant and to identify technical challenges as well as research needs. • The resulting redox material heating profile in case of R2Mx shows substantial advantages compared to the state-of-the-art. • Competitive average annual plant efficiencies of up to 10.5 % and further significant improvement potential are identified. [ABSTRACT FROM AUTHOR]

With a focus on a class of origami-inspired metamaterials, this work explores the role of panel confinement in their mechanical response under cyclic loading. The goal is twofold: (i) quantify the magnitude change in snapping force and energy dissipation attained by varying the severity of confinement of selected panels; and (ii) leverage insights to modulate in situ their mechanical response as dictated by a given application, hence propose panel confinement modulation as a practical design route for response reprogrammability. Through computational modelling, proof-of-concept fabrication and cyclic testing, we first identify and characterize the governing factors enabling either the alteration or the preservation of the snapping force magnitude during repeated cycles of forward and backward loading. Then, we demonstrate how the in situ modulation of the constrained distance between selected panels enables reprogramming their snapping sequence and energy dissipation. The results contribute to expanding the versatility and application of this class of origami metamaterial across sectors, from aerospace to protective equipment, requiring precise control of mechanical damping and energy dissipation. This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'. [ABSTRACT FROM AUTHOR]

This paper experimentally investigated the in-plane seismic behavior of perforated masonry walls (pier-spandrel substructures) retrofitted using engineered cementitious composites (ECC). One unreinforced masonry (URM) specimen and two ECC-reinforced masonry substructures were prepared and subjected to pseudostatic cyclic lateral loads. The failure mode, hysteretic curves, strength, deformability, stiffness, and energy dissipation capacity of three specimens were compared and discussed. The results revealed that the failure pattern of masonry pier-spandrel substructure was improved by the ECC layer with shear failure of masonry piers changing to bending failure. Multiple thin cracks were observed on the surface of ECC overlay. Moreover, the external ECC layer effectively increased the load-carrying capacity and ultimate deformation of the substructures, with maximum increases of 104% in strength and 72% in ultimate displacement, respectively. Finally, the excellent energy dissipation capacity was obtained by ECC overlay, which can improve the collapse resistance of masonry structures subjected to strong earthquake action. [ABSTRACT FROM AUTHOR]

Confined brick masonry structures have garnered considerable attention as an effective solution for earthquake-prone regions due to their robust construction, efficient wall-to-column connections, and optimised utilisation of material strength. Within the realm of building design and construction, openings play a pivotal role, serving as essential elements for facilitating natural light and fresh air into the structure. However, the presence of openings within confined brick masonry walls causes a significant reduction in their seismic resistance. Hence, striking the right balance between these openings and structural strength is crucial. For this purpose, it is necessary to investigate the influence of size, shape, and position of the openings in confined brick masonry walls on their seismic performance. In this work, a comprehensive finite element macro-model is adopted that treats the wall and tie members as a unified system. A concrete damage plasticity approach is employed to predict damage progression in confined brick masonry walls. Using a pushover analysis in finite element framework, the ultimate strength, stiffness, and energy absorption capacity of confined brick masonry with different types of openings is assessed. Furthermore, a parametric study is conducted incorporating various scenarios, such as aspect ratios of confined brick masonry walls, diverse shapes of opening and variations in the positions of windows, doors, and combinations of both openings. Based on the results, simplified equations are developed to facilitate analytical estimation of ultimate strength, along with recommendations for optimising opening shape, size, and placement to enhance the design of confined brick masonry walls with openings. The study highlights that larger openings in confined brick masonry walls diminish ultimate strength, stiffness, and energy dissipation due to reduced load distribution and increased stress concentrations. Openings smaller than 10% of the masonry area maintain load paths, but larger openings require additional support. Rectangular openings with greater height than width exhibit superior performance. Furthermore, the positioning of windows significantly influences wall strength, with placements farther from the loading point proving favorable. Door placement also impacts ultimate strength, with central placement compromising stiffness. Combining window openings with a centrally located door maintains consistent ultimate strength but affects stiffness. Overall, this research contributes to a better understanding of the seismic behaviour of confined brick masonry structures with openings, offering valuable insights for engineers and architects working in regions susceptible to seismic activity. [ABSTRACT FROM AUTHOR]

Hydrogels, known for their 3D polymer networks and high water content, are widely used in applications ranging from agriculture to tissue engineering and soft electronics. However, balancing toughness and stiffness in hydrogels remains a significant challenge due to the inverse relationship between these properties. In this study, a dual‐network hydrogel is developed composed of lignin/poly(N,N‐dimethylacrylamide) (PDMA) and sodium alginate/Ca2⁺ (SA/Ca2⁺) using a solvent exchange method. This hydrogel incorporates multi‐level energy dissipative structures, resulting in both high stiffness and toughness. Specifically, the DL/S0.1Ca0.5 hydrogel exhibited impressive mechanical performance, including a tensile stress of 3.7 MPa, a tensile strain of 1100%, and a tensile modulus of 8.7 MPa, along with remarkably high toughness of 97,000 J m−2 and work of extension of 25 MJ m−3. Additionally, it demonstrates exceptional rupture and collision resistance, outstanding conductivity of 19.7 S m−1, and high strain sensitivity with a gauge factor up to 7.78. These features highlight its potential for use in extreme sports protection and wearable sensors, representing a significant advancement in the development of multifunctional hydrogels. [ABSTRACT FROM AUTHOR]

Conventional triboelectric generators (TEGs) have been developed to mainly harvest the energy of linear mechanical motions and convert it usually into oscillating or pulsive, but not sustainable, electrical outputs. In this study, unidirectional charge transfer mechanisms are introduced to develop a triboelectric mechanical metamaterial (TMM) with sustainable electrical outputs. Density functional theory and experimental analyses demonstrate three minimum necessary components of TMMs fabricated by only two triboelectric materials (i.e., copper and PTFE) to generate sustainable electrical outputs. Under a wide range of compression‐tension strain of ±50%, the maximum open‐circuit voltage, short‐circuit current, and volumetric power density are 3860 V, 8 µA, and 365.3 kW m−3, respectively. Different from most conventional cellular solids, the mechanical energy dissipation of the TMMs increases quadratically with the unit cell number. High volumetric electromechanical efficiency is achieved when the unit cell is miniaturized. In addition to energy harvesting and mechanical energy dissipation, TMMs can sense the displacement by counting the number of distinctive peaks in the short‐circuit charge transfer or reaction force versus time curves. The extreme electromechanical functionalities of the TMMs facilitate their applications in intelligent suspension systems, miniaturized green power sources, and self‐sensing energy harvesters. [ABSTRACT FROM AUTHOR]

Concrete's dynamic performance and energy dissipation are critical areas of interest that are significantly influenced by strain rate and aggregate content. This study investigated concrete's dynamic deformation, strength development and energy dissipation characteristics from specimens containing 0, 32%, 37% and 42% aggregate. These specimens were subjected to impact compression tests using a split Hopkinson compression apparatus, which allowed the effects of strain rate and aggregate content on the deformation, strength and energy dissipation of the concrete to be analysed. The results show that the concrete exhibits deformation hysteresis under impact loading, with splitting tensile failure as the predominant damage mechanism. Dynamic strength was more sensitive to strain rate than aggregate content. The dynamic increase factor (DIF) varied with aggregate content at different strain rates. The extent of specimen damage significantly influenced the energy distribution ratio, with absorbed energy showing a more pronounced strain rate effect than transmitted and reflected energy. Conversely, the amount of transmitted energy had a more pronounced impact on aggregate content than the amount of absorbed and reflected energy. [ABSTRACT FROM AUTHOR]

The present work investigates factors which control the stress generated at the back face of end wall-mounted shock-loaded aluminum foam. When the applied shock pressure is higher than the plastic strength of the foam, the foam deforms plastically generating a compaction wave traveling below shock velocity. Wave reflection and momentum transfer at the end wall result in shock amplification. With increasing foam length, the stress at the end wall decreases, finally leading to shock mitigation. A relation between compaction wave characteristics, foam densification, and stress generated at the end wall is established. [ABSTRACT FROM AUTHOR]

[Display omitted] The voltage decay of Li-rich layered oxide cathode materials results in the deterioration of cycling performance and continuous energy loss, which seriously hinders their application in the high-energy–density lithium-ion battery (LIB) market. However, the origin of the voltage decay mechanism remains controversial due to the complex influences of transition metal (TM) migration, oxygen release, indistinguishable surface/bulk reactions and the easy intra/inter-crystalline cracking during cycling. We investigated the direct cause of voltage decay in micrometer-scale single-crystal Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (SC-LNCM) cathode materials by regulating the cut-off voltage. The redox of TM and O2− ions can be precisely controlled by setting different voltage windows, while the cracking can be restrained, and surface/bulk structural evaluation can be monitored because of the large single crystal size. The results show that the voltage decay of SC-LNCM is related to the combined effect of cation rearrangement and oxygen release. Maintaining the discharge cutoff voltage at 3 V or the charging cutoff voltage at 4.5 V effectively mitigates the voltage decay, which provides a solution for suppressing the voltage decay of Li-rich and Mn-based layered oxide cathode materials. Our work provides significant insights into the origin of the voltage decay mechanism and an easily achievable strategy to restrain the voltage decay for Li-rich and Mn-based cathode materials. [ABSTRACT FROM AUTHOR]

Solar energy harvesting and storage are essential in the future mix of renewable energy technologies. Hierarchical coral‐structured coatings have been shown to yield high solar absorptance in concentrating solar thermal (CST) systems. However, interfacial delamination and scalability challenges owing to material complexity pose significant hurdles for the widespread industrial adoption of these hierarchical CST coatings. Here, a coral‐structured coating is proposed whose black pigments are strongly bonded by titania, which is a material that mitigates interfacial delamination. Importantly, this coating follows a facile deposition procedure suitable for large‐scale solar receivers. The drone‐deposited coating inhibits cation diffusion and maintains a stable solar absorptance of 97.39±0.20%$97.39\pm 0.20\%$ even after long‐term (3000 h) high‐temperature (800∘C$800 \,^{\circ }\mathrm{C}$) aging. The scalability of developed coating represents a substantial advancement in the implementation of light‐trapping enhancement and maintenance approaches across a wide range of CST applications. [ABSTRACT FROM AUTHOR]

In tapping mode atomic force microscopy (TM‐AFM), the phase image can reveal more about the physicochemical properties of the sample surface than the topography image, making it widely utilized in fields such as materials science and life sciences. However, obtaining high phase contrast in phase images during experiments is challenging, thus studying the phase imaging theory of TM‐AFM and optimizing phase contrast methods hold significant importance. This paper derives a theoretical expression for phase contrast based on phase theory, discovering that phase contrast is directly related to the frequency ratio and background dissipation quality factor. Through theoretical, experimental, and simulation approaches, optimization methods for phase contrast were proposed from the perspectives of frequency ratio and background dissipation quality factor as follows: (1) By fitting experimental results with the theoretical expression for phase contrast, the optimal frequency ratio for scanning can be determined, and imaging with this optimal ratio can enhance phase contrast and (2) reducing the width ratio between the free and fixed ends of the probe can decrease background dissipation, increase the proportion of core dissipation in the total energy dissipation of the probe, and thereby improve phase imaging contrast. These findings are significant in guiding TM‐AFM phase scanning experiments and optimizing phase imaging contrast. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomers (LCEs) exhibit extraordinary energy dissipation due to their unique viscoelastic response, resulting from the rotation of mesogens under mechanical stress. While recent studies demonstrate the LCE‐based pressure‐sensitive adhesives (PSAs) by exploiting the enhanced damping, all previous studies have focused on LCEs with covalent crosslinks. Here, a new class of PSAs is developed by integrating movable polyrotaxane crosslinkers into an LCE matrix (PRx‐LCEs). Dynamic viscoelastic measurements reveal that PRx‐LCE exhibits a remarkably high energy dissipation, as indicated by a large tan δ. Interestingly, the secondary tan δ peak associated with LCE damping is more pronounced than the primary peak of the glass transition. The exceptional energy dissipation in PRx‐LCE results in superior adhesion strength (≈1864 N m−1), which is 3.5 times higher than conventional LCEs and 13 times higher than commercial PSAs in the peel test. Additionally, PRx‐LCEs demonstrate thermally reversible adhesion, enabling clean removal at elevated temperatures. Furthermore, the sliding effect in PRx‐LCE enhances both deformability and stress relaxation under load, resulting in deeper indentation, and superior adhesion during the probe tack test. The combination of LCE and slidable crosslinks provides robust and switchable adhesion, making them promising for applications in biomedical engineering, display, and semiconductor industries. [ABSTRACT FROM AUTHOR]

The modular structure of small molecular acceptors (SMAs) allows for versatile modifications of the materials and boosts the photovoltaic efficiencies of organic solar cells (OSCs) in recent years. As a critical component, the endcaps of SMAs have been intensively investigated and modified to control the molecular aggregation and photo‐electronic conversion. However, most of the studies focus on halogenation or π‐fusion extension of the endcap moieties, but overlook the non‐fused π‐extension approach, which could be a promising strategy to balance the self‐aggregation and compatibility behaviors. Herein, we reported two new acceptors namely BTP‐Th and BTP‐FTh based on non‐fused π‐extension of the endcap by chlorinated‐thiophene, of which the latter molecule has better co‐planarity and crystallinity because of the intramolecular noncovalent interactions. Paired with donor PBDB‐T, the optimal device of BTP‐FTh reveals a greater efficiency of 14.81 % that that of BTP‐Th (13.91 %). Nevertheless, the BTP‐Th based device realizes a lower energy loss, enabling BTP‐Th as a good candidate to serve as guest acceptor. As a result, the ternary solar cells of PM6 : BTP‐eC9 : BTP‐Th output a champion efficiency up to 18.71 % with enhanced open‐circuit voltage. This study highlights the significance of rational decoration of endcaps for the design of high‐performance SMAs and photovoltaic cells. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) is widely recognized as a low-cost alternative to iridium as anode electrocatalyst in proton-exchange membrane water electrolyzers (PEMWE). However, the reported Ru-based catalysts usually only operate within tens of hours in PEMWE because of their intrinsically high reactivity of lattice oxygen that leads to irrepressible Ru leaching and structural collapse. Herein, we report a design concept by employing large-sized and acid-resistant lattice lead (Pb) as a second element to induce a pinning effect for effectively narrowing the moving channels of oxygen atoms, thereby lowering the reactivity of lattice oxygen in Ru oxides. The Pb-RuO2 catalyst presents a low overpotential of 188 ± 2 mV at 10 mA cm−2 and can sustain for over 1100 h in an acid medium with a negligible degradation rate of 19 μV h−1. Particularly, the Pb-RuO2-based PEMWE can operate for more than 250 h at 500 mA cm−2 with a low degradation rate of only 17 μV h−1. Experimental and theoretical calculation results reveal that Ru-O covalency is reduced due to the unique 6s−2p−4d orbital hybridization, which increases the loss energy of lattice oxygen and suppresses the over-oxidation of Ru for improved long-term stability in PEMWE. Developing robust catalysts for proton-exchange membrane water electrolyzers is essential for industrial applications. Here, the authors report a Pb-RuO2 catalyst that uses large-sized Pb to reduce the reactivity of lattice oxygen, enhancing stability and allowing it to operate for over 1100 h. [ABSTRACT FROM AUTHOR]

This study investigates the visible light‐assisted photocatalytic degradation of rhodamine B (Rh B) dye using MoS2–CdS nanocomposite. Two crucial operational parameters, illumination time and the weight ratio of MoS2 to CdS, are systematically examined. Approximately, 91.9% of Rh B solution with a concentration of 10 mg/L is degraded by the MoS2–CdS photocatalyst under 60 min of illumination, with a photocatalyst dosage of 0.5 g/L. The results are consistent with a pseudo‐first‐order kinetic model, wherein the degradation rate constant of CdS increases fourfold after amalgamation with MoS2. The formation of the composite with MoS2 results in 1.72 times increase in the apparent quantum yield and 3.15 times decrease in the electrical energy consumption per order of CdS nanorods under similar experimental conditions. The investigation also comprehensively explores the reactive species responsible for Rh B degradation under visible light in the presence of MoS2–CdS photocatalyst. This analysis confirms that both hydroxyl and superoxide anion radicals play a dominant role in Rh B degradation. These findings underscore the potential practical applications of MoS2–CdS nanorods in eco‐friendly water treatment technologies, offering efficient and sustainable solutions to contemporary environmental challenges. [ABSTRACT FROM AUTHOR]

This research investigates the structural performance and failure mechanisms of beam‐column joints reinforced with aramid fiber‐reinforced polymer to bolster the durability and seismic resilience of concrete structures. It meticulously selects and proportions materials such as ordinary Portland cement Grade 53 cement, fine and coarse aggregates meeting IS: 383–1970 standards, and water conforming to IS: 456–2000 specifications. Tests confirm the high quality of ordinary Portland cement, crucial for optimal beam‐column joint performance, while carbon fiber‐reinforced polymer enhances structural integrity with its lightweight composition and substantial tensile strength (3800 MPa–4200 MPa). Failure analysis reveals that non‐aramid fiber reinforced polymer wrapped beam‐column joint specimens predominantly failed due to concrete crushing, whereas aramid fiber‐reinforced polymer‐wrapped specimens failed due to fracture in the aramid fiber‐reinforced polymer composite, emphasizing stress concentration areas. This study underscores the pivotal role of stress distribution in failure mechanisms and underscores the significance of robust reinforcement design in bolstering structural resilience. These insights advance retrofitting strategies and reinforce techniques aimed at enhancing the longevity and seismic resistance of concrete structures. [ABSTRACT FROM AUTHOR]

Synaptic plasticity, the dynamic tuning of signal transmission strength between neurons, serves as a fundamental basis for memory and learning in biological organisms. This adaptive nature of synapses is considered one of the key features contributing to the superior energy efficiency of the brain. Here, we use molecular dynamics simulations to demonstrate synaptic-like plasticity in a subnanoporous two-dimensional membrane. We show that a train of voltage spikes dynamically modifies the membrane's ionic permeability in a process involving competitive bicationic transport. This process is shown to be repeatable after a given resting period. Because of a combination of subnanometer pore size and the atomic thinness of the membrane, this system exhibits energy dissipation of 0.1 to 100 aJ per voltage spike, which is several orders of magnitude lower than 0.1 to 10 fJ per spike in the human synapse. We reveal the underlying physical mechanisms at molecular detail and investigate the local energetics underlying this apparent synaptic-like behavior. [ABSTRACT FROM AUTHOR]

Using the AC electric field to induce the orientation of nonlinear conductive fillers in composites is an effective solution for alleviating electric field distortion in power modules. However, the mechanism by which the electric field affects the filler dynamic characteristics and the composites' electrical properties remains unclear. In this paper, the correlation between the microscopic dynamic processes of fillers and the macroscopic current amplitude was analyzed. The results show that the current increases rapidly (0 ∼ 173 s) and then slowly (173 ∼ 869 s) at 600 V mm−1, influenced by the rotation and attraction processes of the fillers. This demonstrates that the orientation stops at about 869 s and the filler orientation state is a key factor in determining the dielectric properties. Secondly, the global orientation evaluation index D for the filler network was proposed, which can also derive the minimum time and energy loss required for preparation. Finally, the impact of different filler orientations on the composites' conductivity was investigated. In the low electric field stress region, with the average carrier jump distance decreasing from 150.23 to 109.71 nm as the D increases from −0.93 to −0.05. On this basis, materials with nonlinear conductivity gradient distribution can be easily prepared. Before optimization, the electric field stress of the power module at the triple point was 35.79 kV. This composite can reduce the value to 15.42 kV, a decrease of 56.9%, while maintaining good electric field uniformity. [ABSTRACT FROM AUTHOR]

The current industrial wireless sensor network (IWSN) cluster routing methods suffer from energy inefficiency. Designing efficient cluster-based routing protocols is crucial for improving network performance and energy efficiency. Therefore, this paper first designs a new clustering model to achieve efficient cluster head (CH) selection and data transmission performance by comprehensively considering multiple key factors such as CH energy, base station (BS) distance, packet loss rate, and data delay. Based on this clustering model, a novel cluster routing protocol based on Gaussian mutation adaptive artificial fish swarm algorithm (GAAFSA) is proposed. At the same time, a new Gaussian mutation strategy and an adaptive strategy were introduced to effectively promote the protocol to avoid local optima and prevent premature convergence. The GAAFSA based cluster routing protocol was experimentally compared with five popular schemes, namely CMSTR, D2CRP, EEHCHR, ESCVAD and BAFSA. The results showed that the proposed protocol outperformed the other four schemes in terms of network energy consumption, system lifetime, data transmission reliability, and latency. Specifically, GAAFSA has improved network lifespan by at least 15.68%, BS received packets by at least 7.46%, and reduced packet loss rate by at least 15.28%. Therefore, GAAFSA effectively optimizes network performance and extends network lifespan, greatly reducing energy loss within the network and significantly improving network quality of service (QoS). [ABSTRACT FROM AUTHOR]

From 21 August to 15 September 2022, a WindCube v2 Infrared coherent Doppler Lidar (DL) supplied by EKO Co. (Japan) was deployed at the Shigaraki MU Observatory (Japan) near the LQ7 UHF (1.357 GHz) wind profiler in routine operation. Horizontal and vertical velocity measurements from DL were reliably obtained in the [40–300] m height range with vertical and temporal resolutions of 20 m and 4 seconds, respectively. The LQ7 wind measurements are collected with range and temporal resolutions of 100 m and 59 s, respectively, and 10-min average profiles are calculated after data quality control. Reliable LQ7 Doppler data are collected from the height of 400 m. Despite the lack of overlap in the height range, we compared the Turbulence Kinetic Energy (TKE) dissipation rate ε in the daytime planetary boundary layer estimated by the two instruments. A method based on the calculation of the one-dimensional transverse line spectrum of the vertical velocity W from mean W time series (TS method) was applied to DL (ε DL). The same method was also applied to 1-min LQ7 data (ε LQ 7TS) to assess its performance with respect to DL despite the poorer time resolution. A more standard method based on the Doppler Spectral width (DS) was also applied to LQ7 (ε LQ 7DS) from the 10-min average profiles. We tested recently proposed models of the form ε=σ3/ L where σ is half the spectral width corrected for non-turbulent effects and L is assumed to be a constant or a fraction of the depth D of the Convective Boundary Layer (CBL). The main results are: (1) For the deepest CBLs (max(D) >~1.0 km) that develop under high atmospheric pressure, the time-height cross-sections of ε LQ 7DS and ε DL show very consistent patterns and do not show any substantial gaps in the transition region of 300–400 m when ε LQ 7DS is evaluated with L ~70 m , which is found to be about one tenth of the average of the CBL depth (L ~0.1 D). (2) Hourly mean ε DL averaged over the [100–300] m height range is on average about twice the hourly mean ε LQ 7TS averaged over the [400–500] m height range when D >~1.0 km. (3) Hourly mean ε DL averaged over the [100–300] m height range and hourly mean ε LQ 7DS averaged over the [400–500] m height range with L ~0.1 D are identical on average. Consistent with the fact that ε is expected to decrease slightly with height in the mixed layer, (2) and (3) imply an uncertainty as to the exact value of the L / D ratio: ~0.1 D < L <~0.2 D. We have also studied in detail the case of a shallow (D <~0.6 km) convective boundary layer that developed under low atmospheric pressure and cloudy conditions. Despite the fact that hourly mean ε DL averaged over the [100–300] m height range and hourly mean ε LQ 7TS averaged over the [400–500] m height range show more significant discrepancies, maybe due to the different properties of the shallow convection, the time-height cross-sections of ε DL and ε LQ 7DS show more consistent patterns and levels. [ABSTRACT FROM AUTHOR]

The tuned viscous mass damper (TVMD) exhibits superior control effect and energy dissipation capability compared to the viscous damper (VD). Existing literature has primarily focused on the control of absolute acceleration response in structures by linear TVMD, with limited research on nonlinear damper for controlling structural performance and efficiency. This study proposes a methodology for determining the optimal parameters of linear TVMD. The closed-form solution of the nonlinear TVMD is derived through stochastic linearization based on the linear TVMD, aiming to minimize the damping ratio of TVMD by utilizing the damping enhancement effect of the system. For lightly damped structures, the closed-form solution remains a reliable method for accurately approximating TVMD design parameters. Compared to traditional fixed-point theory, the TVMD developed through the proposed methodology demonstrates superior control performance, especially in terms of absolute acceleration, with a smaller damping ratio and minimal deviation from the optimal state of the TVMD. Additionally, the study investigated the influence of the damping index on the optimal parameters and the efficacy of the TVMD in vibration control. It is observed that reducing the damping index can improve structural performance, particularly in long-period structures with small mass ratios, although it may reduce the efficiency of the TVMD. Notably, TVMDs with lower mass ratios maintain higher efficiency regardless of the structural natural period. The damping index does not affect the optimal frequency ratio or the mean square response. Ultimately, the effectiveness of the optimization method is displayed through the examination of response spectra following 22 real seismic events, showcasing its adaptability across various structural types. The comparison of the root-mean-square response between the VD and TVMD across different periods shows consistent results, with a maximum deviation of only 10%. The TVMD is highly effective at regulating the structural response, excelling particularly in controlling the absolute acceleration of long-period structures, where it reduces maximum absolute acceleration by 20% more than displacement. The proposed exact solution rapidly and precisely identifies the design parameters of nonlinear TVMD by the desired specifications, thereby offering theoretical guidance for practical engineering applications. [ABSTRACT FROM AUTHOR]

Background Method Results Conclusion An innovative solution has been recently proposed for the treatment of heart failure with preserved ejection fraction (HFpEF), using a centrifugal mechanical circulatory support (MCS) device. We sought firstly to assess the hemocompatibility of the proposed device. HFpEF treatment requires the blood pump to operate at low blood flow rate (0.05–0.5 L/min). Given high blood trauma expected in these conditions, we sought secondly to investigate design improvements in order to reduce this risk.Computational fluid dynamics was used to analyze the blood fluid filled within the centrifugal pump and to estimate the blood trauma due to its operation. This assessment is based on the computation of integrated quantities such as the hemolysis index and the turbulent dissipation energy.The hemolysis index associated with the present device is comparable to the figures from HVAD. With the proposed pump, for instance, an index of 0.0036 is obtained at 1 L/min and 3000 rpm. Using thinner blades for the impeller allows a 12% reduction of the hemolysis index in average, while reducing its diameter leads to an index 2.8 folds lower at 0.5 L/min.The present investigation shows the promising hemocompatibility of our centrifugal pump. Concerns about very high hemolysis generated at low flow rates could be overcome by reducing the impeller diameter. Experimental validations are planned to support our findings. [ABSTRACT FROM AUTHOR]

To investigate the dynamic mechanical behavior and energy dissipation characteristics of low-temperature rock samples under cyclic impact loading, a temperature-controlled impact system that combines Hopkins bars with a low-temperature compensation device was used. Five temperature gradients were confirmed via a trial impact test, and impact tests were conducted under two kinds of impact air pressures. The macroscopic damage characteristics of rock samples under cyclic impact at different temperatures, dynamic stress-strain curves, changes in peak stress and strain, energy dissipation, and cumulative damage at different temperatures, and the macroscopic and microscopic structural characteristics of low-temperature rock samples after cyclic impact were analyzed in combination with damage. The findings indicated that low-temperature saturated granite primarily experienced tensile damage under cyclic impact loading, with the required number of impacts increasing with decreasing temperature, and rock samples exhibited freeze-induced brittleness and significantly increased fragmentation. The dynamic stress-strain curve generally exhibited rebound characteristics in the post-peak stage. With an increasing number of cycles, an overall decrease in peak stress was observed, whereas the peak strain and cumulative specific dissipated energy exhibited opposite trends. This trend was more pronounced at lower temperatures, with a significant increase in peak strain and specific energy amplitude. In addition, the cumulative damage factor of the rock samples increased at lower temperatures, consistent with macroscopic damage characteristics, and exhibited a negative correlation with peak stress. The degree of crack extension in the macroscopic samples corresponded with the observed fracture changes. Microanalysis (SEM) indicated that decreasing temperature resulted in freeze brittleness of the fracture surfaces, characterized by reduced flatness and an expansion of brittle cracks across the damage surface. The slip separation phenomenon became increasingly pronounced, and these observations were positively correlated with the cumulative damage value. [ABSTRACT FROM AUTHOR]

β-quartz is an important component that affects the physical and chemical properties of glass-ceramics. The material removal process of ion beam machining is complicated as one of the ultra-precision machining forms. Therefore, it is important to understand the removal mechanism of ion beam machining materials. The methods of molecular dynamics (MD) and first-principles were adopted to investigate the microscopic mechanism of ion beam bombardment of the β-quartz structure. The damage evolution of structures and the evolution of material properties caused by defects respectively from the atomic and electronic levels. Through MD analysis, we find that the random collision between incident ions and matrix atoms can lead to the formation of sputtered atoms. The incidence of ions will increase the disorder degree of the matrix, and the influence on the disorder degree at different depths of the matrix is different. The degree of disorder increases obviously in the range of 50–70 Å from the surface of the matrix. It has a significant impact on the surface topology of the matrix, the number of defects, surface roughness, and matrix density. The results of first-principle calculation show that the refraction, absorption and other characteristics of the system are significantly different with different doping forms, and the energy loss is most affected by substituted doping. And the substituted doping defects have the most significant effects on the structural energy loss. Among, the Ar-substituted O doping structure leads to higher energy loss, and the peak energy loss intensity reaches 5.146. In contrast, the Ar-substituted Si doping structure causes the least energy loss, the intensity is 2.543. This study provides a theoretical basis for the selection of parameters and the realization of ultra-smooth surface in actual ion beam machining. [ABSTRACT FROM AUTHOR]