Dissipation Research Articles

A material dynamically enhancing both load-bearing and energy dissipation capability under cyclic loading.

Material properties gradually degrade under cyclic loading, leading to catastrophic failure. It results in large costs for inspection, maintenance, and downtime. Besides, materials require combinations of performance such as load bearing and energy dissipation. However, improving one performance of a material often sacrifices another performance, making it difficult to create materials with optimal performance profiles. Here we report a liquid-infused porous piezoelectric scaffold (LIPPS) that simultaneously enhances its load-bearing and energy dissipation capability under cyclic loading. For example, after 12 million loading cycles, LIPPS increases its modulus by 3600% and hysteresis by 3000%. From a CT study, this behavior is attributed to the self-recoverable mineralization under mechanical loading. Moreover, LIPPS shows a reprogrammable stiffness distribution based on the loading distribution, which enables the material to generate multiple shapes by self-folding. Our findings can contribute toward unprecedented opportunities in soft robotics, vehicles, infrastructure, and tissue engineering and contribute to the new paradigm of material selection with improved resilience and sustainability.

Experimental Study on Repairing and Strengthening Seismically Damaged RC Frames by Installing H-Shaped Steel

Seismic disaster investigations worldwide have revealed that a large number of reinforced concrete (RC) frame structures have been damaged or even collapsed. However, most of these buildings exhibit minor or moderate damage and can be repaired and strengthened. “Strong columns and weak beams, strong joints and weak components” is the concept of seismic design of buildings, and the failure of beam–column joints and columns is considered nonideal. For RC frame structures with damaged joints and columns, a method for repairing and strengthening damaged frames by installing H-shaped steel and pouring grout is proposed. By applying a pseudo static load, a frame structure specimen was damaged to simulate earthquake damage. After removing the crushed concrete, the damaged frame was repaired by pouring grout. Then, the structure was further strengthened by installing H-shaped steel on the columns using post-installed anchors. Through loading tests, seismic indices such as strength, deformation capacity, energy dissipation and failure mode of the frame before and after strengthening were compared. The results showed that the seismic performance of the repaired and strengthened frames exceeded that of the original frame, and the failure mode of the frame changed from joint shear and column-end bending to ideal beam-end yielding. Installing H-shaped steel and pouring grout could effectively strengthen the damaged frame, which provides a solution for repairing and upgrading damaged RC framed structures with a nonideal failure mode.

Respiratory abnormalities in sarcoidosis: physiopathology and early diagnosis using oscillometry combined with respiratory modeling

BackgroundSarcoidosis is a multisystemic syndrome of uncertain etiology with abnormal respiratory findings in approximately 90% of cases. Spirometry is the most common lung function test used for assessing lung function in diagnosis and monitoring pulmonary health. Respiratory oscillometry allows a simple alternative for the analysis of respiratory abnormalities. Integer-order and fractional-order modeling have increasingly been used to interpret measurements obtained from oscillometry, offering a detailed description of the respiratory system. In this study, we aimed to enhance our understanding of the pathophysiological changes in sarcoidosis and assess the diagnostic accuracy of these models.MethodsThis observational study includes 25 controls and 50 individuals with sarcoidosis divided into normal to spirometry (SNS) and abnormal spirometry (SAS). The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC).ResultsThe integer-order model showed significant airway and total resistance increases in the SNS and SAS groups. There was a reduction in compliance and an increase in peripheral resistance in the SAS group (p < 0.001). The fractional-order model showed increased energy dissipation and hysteresivity in the SNS and SAS groups. Correlation analysis revealed significant associations among model and spirometric parameters, where the strongest associations were between total resistance and FEV1 (r: -0.600, p = 0.0001). The diagnostic accuracy analysis showed that total resistance and hysteresivity were the best parameters, reaching an AUC = 0.986 and 0.938 in the SNS and SAS groups, respectively.ConclusionThe studied models provided a deeper understanding of pulmonary mechanical changes in sarcoidosis. The results suggest that parameters obtained through the studied models enhance evaluation and enable better management of these patients. Specifically, total resistance and hysteresivity parameters demonstrated diagnostic potential, which may be beneficial for the early identification of individuals with sarcoidosis, even when spirometry results are within normal ranges.

Numerical investigation of water droplet collision dynamics on moving surfaces

This work presents a comprehensive numerical study on the dynamics of droplet collision on a moving solid surface with different wettabilities. Results of numerical simulations for the cases of both stationary and moving substrates are compared with the corresponding experimental results. The spreading of droplets, lamella formation, and recoil in dependence on droplet size, impact velocity, and motion of the surface are discussed in the present work. The results demonstrate that with large drops and high surface velocities, droplet deformation is strongly asymmetric due to the competition between normal and tangential forces. Also, detachment of the lamella becomes stronger by increasing the speed of the surface; hence, there is only a little recoiling contact with increased energy dissipation. In contrast, the smaller droplets had a quite stable spreading with no lamella breakup at all, which is evidence again for the decisive action of droplet size and kinetic energy in dynamics after impact. Among the other manifestations, the present study points out the formation of a central splash in the larger droplets. These facts increase awareness in droplet dynamics concerning moving surfaces with applications in optimizing the efficiency of industrial processes like inkjet printing, spray cooling, and surface coating technologies.

On-Site Nanowire Growth of Peptides Enables Stable Amine Selective QCM Gas Sensing.

Here, we demonstrate a novel methodology for developing stable quartz crystal microbalance (QCM) gas sensors tightly decorated with self-assembled peptide nanowires as sensitive materials for the first time. When employing a conventional drop-casting method for decorating self-assembled peptide nanostructures onto a QCM electrode surface, observed sensor signals significantly exhibited background noise via unintentional energy dissipations. To overcome this inherent problem of depositing peptide self-assemblies, we developed an on-site growth method of peptide nanowires directly grown from a peptide amorphous film on a QCM electrode surface. The QCM sensors fabricated by the on-site growth method exhibited smaller background noise with lower energy dissipation, resulting in successful amine selective sensing. Thus, the present method using on-site growth will be a foundation to apply various functional peptide nanostructures to QCM gas sensors.

Dielectric properties of functionalized natural fiber reinforced electromagnetic composite with reduced graphene oxide nanofiller for microwave absorption

AbstractThe integration of 5G technology with advanced electronic devices has intensified electromagnetic pollution concerns, necessitating materials capable of mitigating electromagnetic interference (EMI). This has spurred the development of sustainable alternatives, surpassing conventional synthetic and ferrite materials. Natural fibers, when combined with nanomaterials, exhibit unique properties suitable for EMI shielding. Sugarcane bagasse fiber (SBF), in conjunction with nanofillers such as reduced graphene oxide (rGO), provides a sustainable, lightweight, and eco‐friendly solution for absorbing electromagnetic waves. This study explores the effects of SBF particle size and rGO integration on dielectric and microwave absorption properties. Experimental findings highlight that the EPSB150@1%rGO composite (150 μm SBF with 1 wt% rGO) achieved a maximum dielectric constant (ε′) of 6.62 at 8 GHz, outperforming EPSB@1%rGO (ε′ = 5.45), indicating enhanced charge storage. The dielectric loss (ε″) peaked at 0.41 for EPSB@1%rGO, reflecting superior energy dissipation from interfacial polarization. Reflection loss (RL) calculations revealed improved microwave absorption of −20.07 dB at 12.4 GHz for EPSB150@1%rGO, compared to −15 dB for EPSB@1%rGO, signifying effective EM wave attenuation. These results demonstrate that reduced SBF particle size combined with rGO incorporation significantly enhances dielectric and microwave absorption properties, establishing these composites as promising candidates for EMI shielding and stealth technologies.Highlights 5G technology raises EMI pollution, needing sustainable shielding materials. Sugarcane fiber combined with rGO forms eco‐friendly EMI shielding composite. EPSB150@1%rGO max ε′ = 6.62 at 8 GHz, surpassing conventional composites. Reflection loss of −20.07 dB at 12.4 GHz, high EM wave attenuation. EPSB150@1% rGO boost dielectric and microwave absorption.

Differences in Tolerance of Alnus cordata (Loisel.) Duby and Tilia × europaea L. ‘Pallida’ to Environmental Stress in the First Year After Planting in Urban Conditions

The success of establishing new trees in cities and their subsequent growth depend, among others, on the proper selection of tree species which can easily tolerate the post-planting stress. In the spring of 2023, young Italian alder (Alnus cordata (Loisel.) Duby) and common lime (Tilia × europaea L. ‘Pallida’) trees were planted in a street of heavy traffic in Warsaw. In the summer of 2023, leaf samples were collected during the growing season for chlorophyll a fluorescence measurements and chemical analyses. Additionally, the autumn phenological phases were monitored. Chlorophyll a fluorescence measurements revealed higher values of Fv/Fm, density of reaction centers per cross-section, and electron transport chain efficiency between photosystems II and I, as well as lower energy dissipation rate per active reaction center of photosystem II in A. cordata. Moreover, A. cordata revealed higher chlorophyll a, chlorophyll b, and carotenoid content. The flavonoid and proline content in both species was the highest by the end of July and then decreased. In T. × europea ‘Pallida’, the contents of these stress biomarkers increased in the late growing season. Our results showed that T. × europaea ‘Pallida’ is less resistant to post-planting stress in urban conditions, while A. cordata showed higher resistance to variable weather conditions, high photosynthetic efficiency, and long foliage lifespan.

R Version of the Kedem–Katchalsky–Peusner Equations for Liquid Interface Potentials in a Membrane System

Peusner’s network thermodynamics (PNT) is an important way of describing processes in nonequilibrium thermodynamics. PNT allows energy transport and conversion processes in membrane systems to be described. This conversion concerns internal energy transformation into free and dissipated energies linked with the membrane transport of solutes. A transformation of the Kedem–Katchalsky (K-K) equations into the R variant of Kedem–Katchalsky–Peusner (K-K-P) equations was developed for the transport of binary electrolytic solutions through a membrane. The procedure was verified for a system in which a membrane Ultra Flo 145 Dialyser separated aqueous NaCl solutions. Peusner coefficients were calculated by the transformation of the K-K coefficients. Next, the coupling coefficients of the membrane processes and energy fluxes for electrolyte solutions transported through the membrane were calculated based on the Peusner coefficients. The efficiency of energy conversion in the membrane transport processes was estimated, and this coefficient increased nonlinearly with the increase in the solute concentration in the membrane. In addition, the energy fluxes as functions of ionic current density for constant solute fluxes were also investigated for membrane transport processes in the Ultra Flo 145 Dialyser membrane.

Axial compressive behavior of GFRP composite spiral ties-reinforced ECC-encased HCFST columns

Aiming to solve the issues of conventional concrete-encased high-strength concrete-filled steel tube (HCFST) columns, a novel GFRP composite spiral ties (GC)-reinforced engineered cementitious composite (ECC)-encased HCFST column was proposed and tested under axial compression in this study. The test variables included encasing cement-based materials, the thicknesses of ECC and steel tube, the compression strength of HSC, and the tie configuration. The test results indicated that the failure mode of the composite columns changed after replacing the outer concrete with ECC, showing that the ECC-encased HCFST columns had excellent integrity. When ECC with the same compression strength was used instead of concrete, the bearing capacity, strength index (SI), ductility ( μ) and energy dissipation ( E d.) of the composite columns were increased by 14.2%, 7.7%, and 81%, respectively. Increasing the thicknesses of ECC and the steel tube significantly improved the composite columns' bearing capacity, and the latter was superior in enhancing the μ and E d. of the columns. Compared with other tie configurations, GC had an outstanding performance in improving μ and E d., reflecting the excellent restraint performance of GC. Furthermore, a calculation method for the axial compressive bearing capacity of GC-reinforced ECC-encased HCFST columns was proposed based on the composite constraint model and the unified theory of strength.

Predicting Energy Budgets in Droplet Dynamics: A Recurrent Neural Network Approach

ABSTRACTThe application of neural network‐based modeling presents an efficient approach for exploring complex fluid dynamics, including droplet flow. In this study, we employ Long Short‐Term Memory (LSTM) neural networks to predict energy budgets in droplet dynamics under surface tension effects. Two scenarios are explored: Droplets of various initial shapes impacting on a solid surface and collision of droplets. Using dimensionless numbers and droplet diameter time series data from numerical simulations, LSTM accurately predicts kinetic, dissipative, and surface energy trends at various Reynolds and Weber numbers. Numerical simulations are conducted through an in‐house front‐tracking code integrated with a finite‐difference framework, enhanced by a particle extraction technique for interface acquisition from experimental images. Moreover, a two‐stage sequential neural network is introduced to predict energy metrics and subsequently estimate static parameters such as Reynolds and Weber numbers. Although validated primarily on simulation data, the methodology demonstrates the potential for extension to experimental datasets. This approach offers valuable insights for applications such as inkjet printing, combustion engines, and other systems where energy budgets and dissipation rates are important. The study also highlights the importance of machine learning strategies for advancing the analysis of droplet dynamics in combination with numerical and/or experimental data.

Numerical Simulation and Optimization Study on the Flow Field Characteristics of a Double-Slot Spillway

To investigate the flow characteristics of a novel dual-slot overflow channel, a research approach integrating physical experiments and numerical simulations was adopted. A three-dimensional model of the overflow channel was developed, employing the RNG k-ε turbulence model and the VOF two-phase flow model to optimize the numerical simulation of the high-low dual-slot flow field. Physical experiments were conducted to verify and analyze the hydraulic characteristics of the high-low overflow channel, including the longitudinal water surface profile and flow patterns. The numerical simulation results aligned well with the physical model test results. By analyzing the flow field of the dual-slot counterflow spillway, the flow characteristics at both the spillway and outlet sections were identified. This study focused on the water surface profile along the spillway, the pressure distribution, and the counterflow characteristics of the protruding water tongue, and explored optimization strategies for the WES surface and spillway design. Physical model tests were conducted on the final optimized design, yielding good agreement between the theoretical predictions and experimental results, thereby confirming the feasibility of the energy dissipation methods for both high and low spillways. The research outcomes offer valuable references for related engineering applications.

Electrically Controlled Spreading of a Surfactant-Laden Droplet on a Viscoelastic Interface.

Electrically induced dynamic spreading of a droplet on a soft surface is characterized by intricate interactions between the moving contact line and the substrate deformation, which are explained by a complex interaction between elastic recovery and viscous dissipation that take place simultaneously. Here, we highlight the significance of an additional modulation in the interfacial energy brought about by the distribution of surfactant molecules surrounding the droplet, which causes an increase in the droplet's spreading rate, rather than the expected decrease in it due to energy dissipation at the viscoelastic interface. We attribute this to repartitioning of the surface energy that results in the dynamic reduction in the solid-liquid interfacial tension, overcoming the substrate viscosity-induced attenuation in the spreading rate. Using a scaling theory on the ensuing change in the contact angle as the droplet spreads dynamically, we further offer quantitative insights into the observed spreading dynamics. These findings allow for the rationalization of the sensitive reliance of droplet spreading on the initial contact angle, a phenomenon that has not yet been understood, in addition to providing a scientific basis for dynamic regulation of droplet spreading on soft biomimetic interfaces.

A multilayer snowflake resonator metamaterial for low-frequency broadband sound absorption

Abstract Low-frequency broadband sound-absorbing structures with smaller thicknesses are the focus of research in noise control. Based on the principle of Helmholtz resonant cavity and the internal spacer chamber division structure, a multilayer snowflake resonator metamaterial (MLSRCM) is proposed. The MLSRCM model is investigated using theoretical and simulation methods, and it is concluded that the MLSRCM has excellent sound absorption performance in the frequency range of 450–950 Hz with a thickness of only 28 mm. This mainly originated from the parallel connection of multi-units as well as the application of the weak resonance effect of coherent coupling and the full utilization of space. The broadband sound absorption mechanism in MLSRCM is theoretically investigated by analyzing the complex frequency plane. Subsequently, the sound absorption mechanism of the structure is further analyzed in terms of sound velocity and power dissipation density. The results show that the MLSRCM has excellent low-frequency broadband acoustic absorption performance, which provides a reference for the design of new acoustic-absorbing metamaterials with small thicknesses.

METHODOLOGY FOR EXPERIMENTAL RESEARCH ON THE DISTRIBUTION OF ENERGY IN THE ELEMENTS OF THE «VIBRATION MACHINE – COMPACTING CONCRETE MIXTURE» SYSTEM

The paper presents a methodology for experimental research on the distribution of energy in the elements of a vibra-tion machine for compacting concrete mixtures. The development of this methodology is based on a thorough analy-sis of existing research methods and the determination of energies in mechanical systems and media. Within the general system of the "vibration machine – compacting concrete mixture," the following subsystems were identified: bearings of the vibration exciter, supports, vibration dampers, reactive and active masses, including the form mass and the compacting concrete mixture. Specific research methods for energy dissipation were determined for each of the mentioned subsystems, preceding relevant modeling. Energy dissipation depends on many factors: the composi-tion and structure of the material, cyclic deformation and stresses arising from the medium’s exposure, the type and parameters of the load, the duration of cyclic deformation, and more. The evaluation criterion for energy dissipa-tion in media is the energy absorption coefficient, which expresses the ratio of energy used to perform the techno-logical process of compaction to the potential energy. The ratio of these energies is considered an independent material characteristic, determined experimentally, taking into account actual technological and operational fac-tors. It was found that the following main methods are used to evaluate energy parameters: phase, damping oscilla-tions, hysteresis loops, energy, and resonance methods. The paper substantiates the methodology for experimental research of parameters and energy indicators of concrete mixture compaction processes. Two models—discrete and continuous—were used in the simulation of these processes.

A Review Article: Mitigation Strategies for Seismic Damage in Structures

This in-depth review article provides a comprehensive analysis of mitigation strategies for seismic damage in structures, focusing on the importance of understanding seismic properties and implementing advanced analysis techniques. The review underscores the critical role of structural properties, including stiffness, strength, and ductility, in designing earthquake-resistant structures. By exploring a range of seismic analysis methods, such as force-based, displacement-based, and numerical approaches, the review highlights the significance of a holistic approach in assessing structural response to seismic events. Moreover, the review delves into innovative methods like subspace system identification for damage detection and statistical analysis of seismic sequences, offering promising avenues for future research. The adoption of passive energy dissipation systems and base isolation techniques emerges as key strategies in reducing seismic damage and enhancing structural resilience. Additionally, the review discusses the potential of machine learning techniques in predicting seismicity rates and improving risk management in seismic-prone areas. By combining traditional and advanced methods, this review sets the stage for further developments in seismic damage mitigation strategies. The integration of technological expertise, scientific aptitude, and interdisciplinary approaches is highlighted as essential in ensuring the built environment adapts to unforeseeable natural forces. Ultimately, this review provides a foundational resource for academics, policymakers, and practitioners in the field of earthquake mitigation and structural safety.

Pearson correlation coefficient as a tool to identify the composite vortex states in a two-band superconducting slab

In this study, we employed the Pearson product-moment correlation coefficient ([Formula: see text]) to identify non-composite vortex states in a two-band superconducting slab. The fractional vortices were simulated using the two-component Ginzburg–Landau equations TDGL, with the link variable method and the healing coupling between the superconducting bands. The coefficient [Formula: see text] was calculated based on the square modulus of the order parameters of the two condensates, providing insight into the correlation between the two bands. Statistically, [Formula: see text] ranges from [Formula: see text]1 to 1, where values approaching 1 indicate composite vortices, while values nearing 0 suggest non-composite vortices. In this context, negative values of [Formula: see text] are irrelevant. The use of this tool enabled us to assess the degree of decoupling (coincidence of the position of the vortex centers in the superconducting bands) within the vortex lattice, allowing for the identification of specific fields and currents associated with the uncoupled vortex states in the superconducting slab. Such findings are crucial for managing energy dissipation in multi-band superconducting materials and manipulation of the vortices state in multi-band superconducting system.

Second-Order, Energy-Stable and Maximum Bound Principle Preserving Schemes for Two-Phase Incompressible Flow

In this paper, we propose several linear fully discrete schemes for the mass-conserved Allen-Cahn-Navier–Stokes equation, based on the generalized stabilized exponential scalar auxiliary variable approach in time and the marker and cell (MAC) scheme in space. It is quite remarkable that our schemes can guarantee second-order accuracy in space provided the maximum bound principle (MBP) is satisfied, whereas most previous work can only possess first-order accuracy in space. We rigorously show that the constructed schemes satisfy the unconditional energy dissipation law and preserve the MBP. Finally, various numerical examples are presented to verify the theoretical results and demonstrate the efficiency of the proposed schemes.

Grazing-Induced Evolutions of Coexisting Orbits in a Vibro-Impact Smooth–Discontinuous Oscillator with a Unilateral Adjustable Rigid Wall

In this paper, a new vibro-impact bistable oscillator by installing an adjustable rigid wall to one side of the smooth–discontinuous (SD) oscillator, is constructed to analytically and numerically reveal its unique global dynamic characteristics. In the unperturbed case, there exist complex unilateral homoclinic structures transversal intersecting, grazing and nonintersecting with the impact boundary due to the adjustability of the rigid constraint. When weak vicious damping, weak periodic excitation and impact energy dissipation are considered, the influences of the adjustable rigid constraint and the evolutions from coexisting periodic orbits to chaos are analyzed through bifurcation diagrams, phase diagrams and Poincaré map and basins of attraction. As the position of the impact boundary moves, the orbits graze multiple times with the boundary, causing period-doubling bifurcations and presenting some new impacting periodic orbits and disconnected chaotic attractors. The vibro-impact SD oscillator also gradually loses stability due to the rapid migration of attractors among coexistence orbits.

Effect of Brief Electrical Stimulation on Cell Biomechanics in Hereditary Sensory Neuropathy.

SH-SY5Y neuroblastoma cells are widely used to model neurodegenerative disorders like Alzheimer's, Parkinson's, Huntington's, and Hereditary Sensory Neuropathy type 1A (HSN-1A), a peripheral nerve condition causing axon degeneration and sensory loss. A cell model of HSN-1A is developed by overexpressing wild-type and mutant SPTLC1 genes (C133W, C133Y, V144D). Cells are cultured on plastic and gold substrates, with brief electrical stimulation applied to the gold-grown cells. Atomic force microscopy (AFM) is used to measure Young's modulus, indentation, and energy dissipation. Finite Element Method and non-linear modeling validate the results. In the absence of stimulation, mutant cells show lower stiffness compared to non-transfected cells, indicating a direct biomechanical impact of the mutations. Brief electrical stimulation significantly increases the stiffness of mutant cells, particularly in C133W (99%), C133Y (100%), and V144D (111%) variants, despite the mutations. Energy dissipation of stimulated V144D cells decreases to levels comparable to untreated non-transfected cells. The simulations support the AFM measurements, demonstrating that brief electrical stimulation can partially reverse the biomechanical effects of gene mutations.

Exact and Approximate Analysis of Structural Models with Linear Viscous or Viscoelastic Dampers and Singular Mass Matrices

This research is concerned with model reduction methods in analysis of structural models with viscous or viscoelastic damping and singular mass matrices. These types of models are commonly used in the preliminary design of building structures containing supplemental damping devices to define locations and parameters of the energy dissipaters. In this paper we develop an exact reduced-order technique for the modal analysis of models with singular mass matrices and viscous or viscoelastic supplemental dampers. Using static condensation of generalized coordinates without mass and no damper connection, and using a transformation using the eigenvectors of the damping matrix, an exact state-space formulation with non-singular mass matrix is developed. The above-mentioned alternative model-reduction strategies are revisited and the accuracy of these methods in the estimation of poles (natural frequencies and damping ratios) and frequency response functions is compared with the exact model. To compare the accuracy of the alternative models developed a simple benchmark structural model with singular mass matrix is used.