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This article provides an overview of the latest results in the field of improving the properties of multiatomic inorganic oxide compounds for scintillators. A possibility to control the spatial distribution of nonequilibrium carriers in the ionization track by creating a compositional disorder in the crystalline matrix is in focus. Managing the disorder at the nanoscale level creates an opportunity for the efficient energy loss by carriers during thermalization, smaller spatial dispersion, and, consequently, more efficient binding into excitons and, further, an increase in the scintillation yield. The methods to produce multicationic crystalline scintillation materials have been discussed. The effectiveness of the approach is confirmed for both activated and self-activated scintillation materials. [ABSTRACT FROM AUTHOR]

Rapid switching of transmission line parameters has emerged as a way to manipulate signals and as a testbed for various electromagnetic processes in time-varying media, including metamaterials. In general, the switching results in wave reflection and transmission similar to that for a spatial interface but at new frequencies. Here, various realizations of parameter switching are studied: connection and disconnection of reactive elements (capacitors and inductors) in series and in parallel. The temporal boundary conditions for the current and voltage distributions are derived rigorously based on the telegrapher's equations that explicitly model additional elements, instead of taking the equivalent values. It is shown that the temporal boundary conditions depend not only on the parameter values before and after switching but on its specific realization. Connecting or disconnecting reactive elements always involves energy losses. When new elements are added, two types of losses are identified. The first type is related to the creation of static magnetic and electric fields in the elements after switching. The second type is related to a very rapid energy dissipation during switching even for a vanishingly small resistivity in the line. When elements are removed, their energy is also removed from the waves. The effects of finite switching times are discussed. This study defines some serious constraints in using switchable transmission lines for the realization of photonic time crystals and efficient wave manipulation without externally added energy. The results are also applicable to wave propagation phenomena in other media with time-varying parameters. [ABSTRACT FROM AUTHOR]

This study investigates the impact of irradiation on solid-state lithium batteries, which is critical for their deployment in challenging environments such as space missions and nuclear facilities. By utilizing Geant4 simulations, we examine the effects of neutrons and gamma irradiation on battery materials, with a particular emphasis on the generation of hydrogen and helium isotopes, non-ionizing energy loss (NIEL), and potential radiation-induced leakage current. Our simulations indicate that the induced radioactivity is negligible at the ex-core site of the pressurized water reactor. Notably, neutron irradiation results in higher NIEL values than gamma rays, suggesting more significant displacement damage in battery materials. In particular, we observe a directional leakage current induced by gamma-ray irradiation, with the solid-state electrolyte LLZTO demonstrating the most pronounced response. This phenomenon could potentially lead to alterations at the electrode/electrolyte interface. These findings provide valuable insights into the design and optimization of solid-state lithium batteries in irradiated conditions. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

The interference among risers has always been a research focus within marine engineering. By riser, we mean the equipment that transports oil, gas, and other fluid media in marine environments, connecting the offshore platform and subsea wellhead. The "unbonded composite riser-smooth riser" serves as the research object of this paper, which experimentally investigates the riser group vibration with multi-spacings. This study reveals the interference mechanism of risers with interlayer slip by reviewing the dynamic response of unbonded composite risers in various arrangements. The results indicate that increasing displacement of a side-by-side unbonded composite riser is subjected to the interference and internal cable interlayer slip at high flow velocities. The displacement interference rate peaks, particularly at S/D = 4 (S/D is the spacing ratio, where S represents the distance between the axis of the two risers and D represents the outer diameter of a riser). By contrast, changes in the spacing ratio have little influence on the dominant frequency. The strong energy dissipation capacity and high mass-damping ratio of side-by-side unbonded composite risers efficiently decrease vibration caused by fluid forces. Side-by-side unbonded composite risers occur in a delayed "lock-in" region as opposed to smooth risers under the same conditions. Furthermore, the wake and clearance flow interference on the unbonded composite riser results in a maximum difference of up to 5 times greater in the average value of displacement interference rate. [ABSTRACT FROM AUTHOR]

In order to investigate the impact of fracturing fluid invasion on the mechanical degradation of deep coal, coal samples treated with five promising fracturing fluids were used for true triaxial compression tests in deep conditions. Due to water–rock reactions, lubrication, and the water wedge effect, the compressive strength of coal samples decreased. The decrease was most significant for coal samples treated with hydrofluoric (HF). The total energy and elastic strain energy of the coal samples first increased and then decreased. In contrast, the dissipation energy increased gradually, and the energy dissipation ratio exhibited a U-shape, decreasing initially and then increasing, with a turning point at the peak strain. However, the inflection point was delayed to varying degrees following treatment with viscoelastic surfactant fracturing fluid (VESFF) and acidic fracturing fluid (AFF), with the delay being more pronounced for AFF. The coal samples treated with anionic VESFF and hydrochloric acid exhibited the highest peaks of total energy and elastic strain energy, along with the fastest growth rate of dissipated energy and the most rapid decrease in the energy dissipation ratio, whereas the coal samples treated with HF exhibited the opposite behavior. All coal samples primarily exhibited shear damage, with a small number of tensile cracks appearing near the shear surface in the VESFF-treated coal samples. The coal samples treated with two types of AFF exhibited shear-tensile composite damage, while the HF-treated coal samples displayed X-shaped cracks. In summary, VESFF holds significant potential for future applications in the development of deep ECBM. [ABSTRACT FROM AUTHOR]

The high-speed coolant pump is a critical component in battery energy storage systems, responsible for circulating heat transfer fluid and enabling efficient thermal energy exchange. This study investigates the effect of blade number (Z = 4–9) on the pump's energy performance and internal flow characteristics through experimental and numerical methods. Results show that as the blade number increases, the head and efficiency initially rise and then decline, with Z = 6, Z = 7, and Z = 8 achieving comparable performance at 1.0Qd. While changes in blade number minimally affect disk, volumetric, and volute efficiencies, they significantly influence hydraulic and impeller efficiencies. Pressure distribution analysis reveals that increasing the blade number to Z = 6 and Z = 7 reduces the low-pressure region at the impeller inlet and improves uniformity. Flow characteristics analysis shows that increasing the blade number reduces flow separation and the "jet-wake" effect but an excessive number of blades also raises turbulent kinetic energy, compromising flow stability. Similarly, entropy production decreases initially but rises again at Z = 8 and Z = 9, resulting in reduced energy performance. Overall, the pump's energy performance and internal flow characteristics follow an "inverted U-shaped" trend as blade number increases, highlighting the importance of selecting an appropriate blade number to improve flow conditions, minimize energy losses, and enhance operational stability. This study provides valuable insights for optimizing blade design in coolant pumps. [ABSTRACT FROM AUTHOR]

Loading distribution significantly affects the flow field in the impeller channel, but research on the effects of different loading distribution forms on the performance of mixed-flow pumps is relatively scarce. In this study, three typical mixed-flow pump models, namely front-loading model (FLM), middle-loading model (MLM), and back-loading model (BLM), were designed by changing the loading distribution at the shroud using the inverse design method. The energy losses within the three models were analyzed quantitatively and visually using the entropy generation method. The results show that using front-loading, middle-loading, and back-loading in the design of mixed-flow pumps improves efficiency under common, low, and high flow rate conditions, respectively; in particular, the efficiencies of the FLM, MLM, and BLM under design conditions were 88.72%, 87.82%, and 87.01%, respectively. The entropy generation analysis indicates that the loading distribution has a minor influence on the energy loss within the impeller, but its influence on the energy loss in the downstream components of the impeller can exceed 30%. Internal flow analysis shows that the effect of loading distribution on the relative velocity and adverse pressure gradient at the impeller outlet is the primary reason for the change in the performance of mixed-flow pumps. [ABSTRACT FROM AUTHOR]

Long-term exposure to extreme heat in mines jeopardizes worker health and reduces productivity. This study introduces and evaluates the air distribution of jet ventilation in crossflow (JVIC) mode for localized mine cooling. Experimental and numerical simulations reveal two distinct wake structures: single wakes for wall-attached and impinging jets, and double wakes for deflected jets, influenced by counter-rotating vortex pair (CVP) structures, which accelerate cooling loss. Key parameters—jet-to-crossflow velocity ratio (R), vent equivalent diameter-to-roadway height ratio (C), and jet-to-crossflow Reynolds number ratio—govern flow modes and CVP dynamics, while jet-to-crossflow temperature ratio (T) primarily affects cooling distribution within the jet, confirming a velocity-dominated flow field. A quantitative model was developed to characterize JVIC air distribution, detailing boundaries, diffusion widths, and velocity and temperature trajectories. The model demonstrates that wall-attached and highly deflected jets enable more stable cooling with slower diffusion and reduced energy loss. Under conditions of R = 1 and C = 3, the jet achieves the highest local cooling effectiveness (εt), maintaining a cooling efficiency of 29.9% at x/dm = 3, demonstrating JVIC's ability to maintain effective cooling over extended distances. A practical evaluation shows that the novel JVIC mode achieves a cooling load of 184.9 kW, reducing energy consumption by 86.7% compared to traditional full-air cooling (1387 kW). These findings highlight JVIC's potential for efficient, targeted mine ventilation, advancing cooling efficiency and energy conservation. [ABSTRACT FROM AUTHOR]

Large pumping systems have emerged as one of the primary areas of energy consumption. During the startup process (SUP) of the axial flow pump system (AFPS), a complex interaction unfolds involving the motion of the cutoff facilities (COF), the acceleration of the pump, and the phenomenon of energy dissipation. The kinematic characteristics of the COF significantly influence the flow patterns, dynamic loads, and energy transfer experienced by the system. This study investigates the energy dissipation mechanism of a prototype AFPS (PAFPS) during SUP, utilizing a combination of experiments on engine starting characteristics, computational fluid dynamics, and in-field measurements of the PAFPS. Two COF motion modes are compared, revealing that accelerated gate opening improves transition efficiency and reduces energy consumption. Key findings highlight that accelerated gate motion minimizes turbulence-induced losses near the COF exit and suppresses high entropy production regions in the impeller domain, leading to smoother and more energy-efficient operations. These insights offer actionable strategies to enhance pump system performance during SUP. [ABSTRACT FROM AUTHOR]

In the process of oil–gas micro-lubrication, the lubricant oil liquids are disturbed by high-speed airflow and are prone to forming oil droplets containing micro-bubbles. Micro-bubbles have a significant influence on the kinetic characteristics of successive/synchronous oil droplet impingement on an oil film and its oil film formation mechanism. Numerical simulations of successive/synchronous oil droplet impinging oil film behavior are based on the coupled level set-volume fraction (CLSVOF) method. The effect of micro-bubbles on the flow dynamics characteristics of the successive/synchronous impinge oil film of double oil droplets is investigated. To investigate the mechanism of jet formation during the impingement process, the law of micro-bubbles influences the formation process of the central and neck jets and their morphology is analyzed. The results show that when micro-bubbles exist, the oil droplet impingement process produces the central jet phenomenon. During successive impingements, the micro-bubble is in the pilot or trailing oil droplet, respectively, and there is a large difference in the jet mechanism generated by these two cases. The energy loss in the successive impingement process is larger when the micro-bubble is inside the pilot oil droplet. The central jet hurts the velocity discontinuity effect of the fluid inside the oil film and plays an inhibiting role in the growth of the crown splash. When the micro-bubble is only within the trailing oil droplet, then the surface tension effect excited by the impingement between the subsequent oil droplet and the flat fluid surface inside the impingement crater will cause a transient sudden reduction in the inner diameter size of the crown splash. During the synchronous impingement, the symmetric micro-bubble impinge mode has a positive effect on both the final horizontal expansion inner diameter of the crown splash and its vertical jet height enhancement. The research method of numerical simulation is used in this study. Seven sets of impingement models under the influence of different micro-bubbles are systematically studied and analyzed under the premise of verifying the feasibility of the numerical method. The results of this study can provide theoretical references for the study of the impingement kinetic behavior and film-forming flow mechanism of highly viscous droplets. [ABSTRACT FROM AUTHOR]

Through molecular dynamics (MD) simulations, the collision of two unequal-size droplets with various diameter ratios (Δ) is elaborately scrutinized over a wide range of impact Weber numbers (We). The dynamic evolutions are carefully observed via visual software, which is found to be very different compared with equal-size collisions. The spreading hysteresis is observed over a full spectrum of We for unequal-size collisions because of the merged droplets experiencing wave-capillary propagation, which is commonly seen at the macro-scale. The merged droplet is always directionally moving toward the negative x-direction, resulting from the existence of an energy difference between two collisional droplets. The variation of Δ and We on unequal-size-induced directional movement is discussed in detail by recording the mass-center variation of merged droplets at different given conditions. The maximum spreading factor of merged droplets, βmax, co, has been discussed by involving Δ into the energy-balance equation. Although the predicted results are slightly lower than MD simulations, this is still the most suitable mode due to the different energy dissipation mechanisms at the nanoscale. How Δ affects the off-center collisions is examined by observing collisional dynamics and drawing phase diagrams with respect to three important characteristic parameters (We, B, and Δ). Finally, we establish a theoretical model for predicting the boundary between coalescence and stretched separation, which agrees well with data extracted from MD simulations. This work paves the way to understand the collision with two unequal-size nanodroplets and provides guidance for nanoscale applications. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of theoretical studies of the possible mechanism of energy dissipation that takes place in the experiments with vibrating quartz fork in superfluid 3He–4He mixtures with high concentration. The possibility and efficiency of the tuning fork radiation of both the second sound wave and the diffusion dissipative wave were investigated. The relationships between the amplitudes of temperature and concentration oscillations in these waves were found and the relative wave intensities were determined. This allowed us to give a possible explanation for observed additional mechanisms of tuning fork attenuation in helium solutions. [ABSTRACT FROM AUTHOR]

This paper examines the circumstances under which a one-degree-of-freedom approximate system can be employed to predict the dynamics of a cantilever beam comprising an elastic element with a significant mass and a concentrated mass embedded at its end, impacting a moving rigid base. A reference model of the system was constructed using the finite element method, and an approximate lowest-order model was proposed that could be useful in engineering practice for rapidly ascertaining the dynamics of the system, particularly for predicting both periodic and chaotic motions. The number of finite elements in the reference model was determined based on the calculated values of natural frequencies, which were found to correspond to the values of natural frequencies derived from the application of analytical formulas. The precision of the parameter identification and the outcomes yielded by the substitute model were validated through the calculation of the regions of stable periodic solutions using the analytical Peterka method. Subsequently, the qualitative and quantitative limits of the substitute model's applicability were determined. The quantitative limits were delineated through the utilization of Lyapunov exponents and characteristics associated with the energy dissipation due to impacts and the average number of impacts per excitation period. These characteristics provide a foundation for the introduction of global distance measures of the dynamic behavior of diverse systems within a specified range of the control parameter. [ABSTRACT FROM AUTHOR]

Uncovering the material dissipation mechanisms of two-dimensional materials is essential for their implementation in advanced devices. While graphene resonators are highly attractive due to their high operational frequency and excellent durability, they dissipate a considerable amount of energy due to significant material dissipation associated with atomic friction manifested by the relative slipping of atomic layers. We mitigate the atomic friction by changing the atomic composition of the devices through the insertion of boron and nitride atoms that create polar interlayer bonds and, therefore, also reduce the energy dissipation. As a case study, we built boron carbonitride (BCN) foam cantilever devices and studied their frequency responses compared to those of their graphene counterparts. Indeed, we show that inserting boron and nitride atoms into the lattice improves the interlayer interactions and, thus, reduces the interlayer atomic friction. In addition, the air dissipation of BCN is also lower than that of graphene. Therefore, we pave the path for the development of BCN devices with tunable dissipation. [ABSTRACT FROM AUTHOR]

In this study, the combination of crossover algorithm and particle swarm optimization—crossover algorithm-particle swarm optimization (CS-PSO) algorithm—to optimize photovoltaic hybrid energy storage scheduling, improving global search and convergence speed, is discussed. The new method reduces energy storage costs and energy losses, ensures supply–demand balance and interaction power constraints, and maintains population diversity through cross-search. The CS-PSO algorithm introduces battery state of charge optimization for energy storage scheduling, improving global search and convergence speed, and obtaining accurate multi-objective scheduling results. The experiment shows that the optimal configuration for photovoltaic energy storage is 10 045 batteries + 687 244 supercapacitors, with a cost of 3.452 × 105 yuan and an energy loss of less than 5%. CS-PSO has similar costs but lower losses and faster convergence compared to traditional methods. [ABSTRACT FROM AUTHOR]

To address the issue of inadequate energy dissipation capacity in current vibration-damping fasteners, this study examined the impact of stiffness and damping factor of vibration-damping fasteners on the vibration attenuation rate of rails, based on the theoretical model of a periodic double-layer support system. An intrinsic manganese–copper (Mn–Cu) damping alloy model was established, and the parameters for the Prony analysis and PRF model were determined to accurately define the hyperelastic and linear viscoelastic properties of the damping alloy in the finite element simulation software. A new type of energy dissipating vibration-damping fastener (NEDF) was designed based on these criteria and practical operational conditions. Static and dynamic stiffness simulation calculations were performed to examine the vibration isolation ability of NEDF, which was then installed in a rail system to conduct hammering tests, aiming to investigate its energy dissipation characteristics. The results indicated that NEDF exhibited a high damping factor and maintained significant vibration isolation capacity, notably enhancing the vibration attenuation rate of the rails and improving energy dissipation capacity. [ABSTRACT FROM AUTHOR]

This study explores the impact of the magnetic field on heat transfer and entropy generation in a simulated electronic device using magnetohydrodynamic principles through a three-dimensional hybrid Runge–Kutta and lattice Boltzmann method. By varying Rayleigh number (Ra) from 103 to 106 and Hartmann number (Ha) between 0 and 100, the research evaluated the influence of these parameters on the average Nusselt number (⟨Nu⟩), heat exchange ratio (R), and entropy generation within a confined cavity. The results demonstrated that higher Ra values, particularly for Ra ≥105, significantly enhance convective heat transfer, as reflected by an increase in ⟨Nu⟩. However, introducing a magnetic field (Ha = 50, 100) diminishes this effect by damping fluid motion, resulting in a reduction of ⟨Nu⟩. The heat exchange ratio increases with Ra, reaching a peak value of 0.93 for Ha = 100 and Ra = 105, indicating improved heat dissipation under the magnetic influence. In terms of entropy generation, at low Ra (Ra = 103), thermal conduction is the predominant heat transfer mechanism, with entropy primarily generated due to thermal effects. As Ra increases to 106, the system shifted toward a convection-dominated regime, where entropy generated by viscous effects becomes more significant. Under stronger magnetic fields, particularly at Ha = 100, magnetic entropy generation emerges as a dominant factor, further increasing energy dissipation. These results suggested that magnetic fields can be strategically applied to optimize thermal management in electronic devices by controlling both heat transfer and entropy generation. The effectiveness of this approach, however, is highly dependent on the specific flow conditions and the strength of the applied magnetic field. [ABSTRACT FROM AUTHOR]

This study investigates the resolution requirements for direct numerical simulation (DNS) of high-pressure transcritical wall-bounded turbulence, focusing on channel and square duct flow configurations subjected to cold (cw) and hot (hw) walls. The applicability of traditional DNS resolution standards to capture first- and second-order flow statistics is critically assessed, emphasizing the complex thermodynamic and hydrodynamic interactions in transcritical fluid regimes. A comprehensive analysis, incorporating spectrograms, dissipation rate distributions, and distribution of Kolmogorov ( η u ), Batchelor ( η T ), and density-gradient ( δ ∇ ρ ) scales has been conducted. The findings reveal that under-resolved grids significantly underestimate the intensity and proximity of the pseudo-boiling region to the hot wall, particularly in channel flows where lateral confinement is absent. In contrast, square duct flows benefit from secondary flow motions, which stabilize and stratify structures in the pseudo-boiling region. Using "traditionally standard" grid resolutions, first-order velocity and temperature statistics are captured with errors generally below 2 %. However, significant discrepancies arise in the turbulent fluctuations, particularly related to energy dissipation for under-resolved cases. To address these issues, the "standard" grid resolution has been refined to better capture local property gradients, their variance, and resulting hydrodynamic and thermophysical scales. For channel flows, the proposed grid features wall-normal resolution requirements of Δ y hw + < 1 and Δ y / η u , Δ y / η T ≲ 3.5 , with streamwise resolutions of Δ x cw + ≲ 8 , Δ x hw + < 10.0 and Δ x / η u , Δ x / η T ≲ 9.0. Spanwise resolutions are limited to Δ z cw + < 2.5 , Δ z hw + < 3.4 and Δ z / η u , Δ z / η u ≲ 3.5. Slightly larger values are applicable for square duct flows. Finally, the resolution requirements obtained are applicable to a wide range of fluids, thermophysical regimes and flow geometries. [ABSTRACT FROM AUTHOR]

Wall roughness in centrifugal pump side chambers significantly affects flow behavior and overall pump performance, yet current research in this area is limited. This study investigates the effects of rough rotor, rough stator, and rough rotor–stator on side chamber flow using numerical simulations and experimental validation. A simplified model is proposed to reduce computational costs, and its accuracy is verified by comparison with a typical centrifugal pump. Using the entropy generation method, the local energy loss and macroscopic fluctuations due to roughness are analyzed. The results show that the effect of rotor roughness plays a dominant role, while the effect of stator face roughness is relatively small. The roughness of the pump chamber walls leads to an increase in centrifugal pump head and a decrease in efficiency. The maximum increase in the centrifugal pump head reaches 1.66% and the maximum decrease in efficiency reaches 1.51% in the studied range. These findings indicate that wall roughness is a key factor in flow losses and potential system instability, with the simplified model offering quick and accurate predictions. [ABSTRACT FROM AUTHOR]

Considering the complex flow characteristics of the water-jet pump and the anisotropy of Reynolds stresses, a hybrid Reynolds-averaged Navier–Stokes/large-eddy simulation method based on von Kármán scale and nonlinear correction has been developed, while its effectiveness has also been verified. The proper orthogonal decomposition method is employed to study the unsteady flow characteristics inside a water-jet pump due to its advantages in flow field analysis. The internal and external characteristics of the water-jet pump under two kinds of inflow conditions are comparatively analyzed, and the intrinsic influence mechanism of nonuniform inflow on the performance of the water-jet pump is investigated. The results indicate that nonuniform inflow causes the overall decrease in the pump head curve, and occurs serious reverse flow at impeller outlet near blade tip region, which in turn generates a large energy dissipation. The flow state is relatively smooth under uniform inflow condition, while the nonuniform inflow makes tip leakage flow induce many unstable flow structures, causing large turbulent kinetic energy and low pressure difference between the pressure surfaces and suction surfaces of impeller blades. There are multiscale flow structures in the water-jet pump, with large scales corresponding to low-order modes, which play a dominant role in turbulent movement and can be used as an important element for evaluating hydraulic performance. The energy content of low-modes is lower and the distribution of flow structures in each-order mode is more chaotic in the water-jet pump for nonuniform inflow compared to the ones for uniform inflow. [ABSTRACT FROM AUTHOR]

The double suction pump as a turbine plays an increasingly important role in energy recovery and hydropower generation due to its stable operation and simple structure. Therefore, optimization research on it is of great significance. In this article, the unique design of the hub structure in double suction pumps consisting of conventional half hubs is proposed to be modified to extend the hub until the outer diameter and analyzed. Numerical calculations based on the shear stress transport (SST) k-ω model and verified by experiments show that the full hub impeller exhibited superior hydraulic performance, with an efficiency about 1%–2% higher than the half hub impeller under all operating conditions. Entropy production theory is employed to analyze energy losses, we found that full hub impellers, compared to half hub models, significantly reduce energy loss, with a maximum reduction of about 5.45%. In addition, the full hub impeller reduces turbulence losses up to 5.32% on the one hand and increases friction losses up to 4.52% on the other hand, but turbulence losses account for a larger proportion of the total losses, so the overall efficiency is improved. [ABSTRACT FROM AUTHOR]

This paper examines the instability and energy dissipation of a high-head Francis turbine during shutdown using improved delayed detached eddy simulation, which involves linearly reducing the guide vane opening from 9.84° (best efficiency point) to 0.8° [Spin-No-Load (SNL)]. The results demonstrate a linear increase in water head, with hydraulic efficiency dropping from 93% to 30%. Pressure fluctuations in the vaneless space are mainly due to blade passing frequency and low-frequency components at SNL. High-amplitude pressure fluctuations occur below 37.4% opening in the draft tube, with the dominant frequency under 0.32 times the blade passing frequency. Three vortex structures are identified within the draft tube, a columnar vortex rope in the first stage, multiple helical vortex ropes in the second stage, and discrete vortex structures in the third stage. The most significant axial and radial velocity fluctuations are evident during the second and third stages. Turbulent kinetic energy generation and work done by Reynolds stress are the main sources of power loss. Energy dissipation primarily occurs at the outlet of the runner blades, while it corresponds to the positions of the vortex structures in the draft tube, suggesting that vortex flow structures are the primary mechanism of energy dissipation in the turbine. This study introduces a numerical shutdown model using the dynamic mesh technique, clarifies the relationship between guide vane opening and performance parameters, and identifies the three-stage vortex evolution and energy dissipation mechanisms, offering novel insights into transient instabilities in high-head Francis turbines. [ABSTRACT FROM AUTHOR]

The side channel pump generates several disadvantage vortices due to abrupt structural changes at the junction of the impeller and side channel, leading to unstable flow, which may induce severe vortex cavitation at the inlet section of the side channel, its impact on the pump's unstable flow mechanism and on the energy conversion characteristics has yet to be thoroughly investigated. This paper explores the effect of backflow vortex on pump performance through optimizing side channel inlet angles by combining the Ω criterion, helicity, and entropy production methods. The computational fluid dynamics numerical simulation's accuracy has been experimentally verified. It was found that increasing the side channel inlet angle could improve internal flow, thereby suppressing backflow vortices and promoting dynamic vortices formation in the inlet section. The backflow vortex is the primary source of high localized energy loss in the inlet section, significantly influencing the reduction of flow loss. It also reduces low pressure areas caused by backflow vortices, thus, restricting cavitation origin. In addition, within a certain range, the flat side channel pump enhances its hydraulic performance, exhibiting the best performance at a 60° inlet angle with an efficiency improvement of 4.6% at the Best Efficiency Flow Point (BEP), which has the most effective backflow vortex suppression, and therefore, lowest flow losses. However, the head improvement was negligible. The performance improvement is due to complete energy conversion within the inlet section. This paper offers new insights into the mechanisms underlying internal energy loss and cavitation characteristics in refining side channel pumps. [ABSTRACT FROM AUTHOR]

Vortices and vortex dipoles play a critical role in turbulence, facilitating scalar mixing, diffusion, and energy dissipation. When a temperature gradient is present, buoyancy effects become significant, and buoyant vortices and dipoles emerge as characteristic features of such flows. In this study, we examine the evolution of a buoyant vortex dipole (BVD) arising from a temperature difference between the vortex dipole and the surrounding fluid. Using the Oberbeck–Boussinesq approximation, we derive the governing equations in non-dimensional form to capture the essential physics. The computational domain is periodic, and simulations are performed using the open-source spectral solver Dedalus. The interplay of thermal diffusion, viscous diffusion, and buoyancy drives the evolution of various coherent structures. Based on these interactions, we identify four distinct topological features and classify the evolution of the BVD into six regimes: (a) thermal diffusion-dominated regime, (b) viscous diffusion-dominated regime, (c) balanced diffusion regime, (d) weak wake street regime, (e) buoyancy-driven transition regime, and (f) multiple tertiary wakes regime. This classification provides a comprehensive framework to understand the dynamics of BVDs under varying physical influences. [ABSTRACT FROM AUTHOR]

This study explores the impact dynamics of emulsion droplets, with a dispersed phase of either silicone oil, toluene, or heptane, and water as the continuous phase, on both smooth and microstructured surfaces fabricated via photolithography. By preparing emulsions without surfactants, we isolated the effects of surface morphology and liquid properties on droplet behavior. We characterized the rheology of the emulsions and their droplet size distributions. The impact dynamics were recorded using a high-speed camera in a shadowgraph configuration, with analysis performed through image processing techniques. Our results indicate that at higher impact velocities, water exhibits the largest spreading diameter ( d max ) on smooth surfaces, while emulsions with higher dispersed phase concentrations show reduced spreading due to increased energy dissipation. On microstructured surfaces, denser structures enhance resistance to spreading and trigger complex phenomena such as Worthington jets and secondary droplets, which are not observed on smooth surfaces. Additionally, we observed a transition in bouncing behavior for the silicone oil 50 cSt 20 v/v% emulsion on Glaco-coated surfaces, attributed to the infiltration of silicone oil into the Glaco microstructure, creating a suction force that prevents bouncing. These findings offer valuable insights for optimizing industrial processes like inkjet printing and pesticide application, where precise control of droplet behavior is crucial. [ABSTRACT FROM AUTHOR]

While perfectly water-repellent surfaces, such as superhydrophobic surfaces, always repel water drops after contact, the drops can either stick to or bounce off lubricant-impregnated surfaces (LISs) depending on the impact conditions. This study investigates the rebound behavior of water drops on LIS, highlighting how this phenomenon significantly depends on both the viscosity of the lubricant and the obliqueness of the surface. Both the lubricant viscosity and surface obliqueness contribute to an increase in dissipation: an increase in lubricant viscosity directly increases the viscous force, and increased surface obliqueness causes the drop to slide on a viscous liquid, resulting in increased dissipation energy. Throughout the study, the dissipation energy attributed to sliding and inelastic collision is addressed. Additionally, we identify an intriguing rotational behavior of drops post-rebound. The direction of rotation varies with the viscosity of the LIS, impact velocity, and surface obliqueness. Numerical simulations demonstrate that this rotation direction is determined by the front and rear velocities of the drop, which is affected by the dynamic advancing and receding contact angles. [ABSTRACT FROM AUTHOR]

Tantalum electrolytic capacitors have performance advantages of long life, high temperature stability, and high energy storage capacity and are essential micro-energy storage devices in many pieces of military mechatronic equipment, including penetration weapons. The latter are high-value ammunition used to strike strategic targets, and precision in their blast point is ensured through the use of penetration fuzes as control systems. However, the extreme dynamic impact that occurs during penetration causes a surge in the leakage current of tantalum capacitors, resulting in a loss of ignition energy, which can lead to ammunition half-burst or even sometimes misfire. To address the urgent need for a reliable design of tantalum capacitor for penetration fuzes, in this study, the maximum acceptable leakage current of a tantalum capacitor during impact is calculated, and two different types of tantalum capacitors are tested using a machete hammer. It is found that the leakage current of tantalum capacitors increases sharply under extreme impact, causing functional failure. Considering the piezoresistive effect of the tantalum capacitor dielectric and the changes in the contact area between the dielectric and the negative electrode under pressure, a force–electric simulation model at the microscale is established in COMSOL software. The simulation results align favorably with the experimental results, and it is anticipated that the leakage current of a tantalum capacitor will experience exponential growth with increasing pressure, ultimately culminating in complete failure according to this model. Finally, the morphological changes in tantalum capacitor sintered cells both without pressure and under pressure are characterized by electron microscopy. Broken particles of Ta–Ta2O5 sintered molecular clusters are observed under pressure, together with cracks in the MnO2 negative base, proving that large stresses and strains are generated at the micrometer scale. ARTICLE HIGHLIGHTS: HIGHLIGHTS • The failure phenomenon of a notable surge in leakage current in two commonly used tantalum capacitors under dynamic impact is investigated. • A mechanical–electrical model for tantalum capacitor electrodes is established at the microscale, and we the complete failure of tantalum capacitors under higher impacts is anticipated. • Morphological changes in tantalum capacitor sintered cells both without pressure and under pressure are characterized by electron microscopy, and it is proved that large stresses and strains are generated at the micrometer scale. [ABSTRACT FROM AUTHOR]

Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion, necessitating robust absorption of visible or near-infrared light, high intersystem crossing efficiency, prolonged triplet state lifetime, and minimal energy dissipation during intersystem crossing and vibrational relaxation. Nonetheless, conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements. In recent years, researchers, including our group, have fabricated photosensitizers that incorporate multiple covalent linkages, such as dyads and triads, which are regarded more likely to achieve comprehensive performance optimization. This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer, demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion. We provide an exhaustive explanation of the design rationales, photophysical, and photochemical properties of these photosensitizers, along with suggestions for the creation of photosensitizers with enhanced performance. Moreover, we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology. [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]