Range Of Fractions Research Articles

Numerical simulation on gas-liquid two phase flow in the U-type pipe

Abstract An effective way to improve the formation of gas hydrate is to increase the gas-liquid contact area, which can also improve the gas-liquid heat and mass transfer efficiency. Designed a natural gas hydrate formation flow experimental device, and a set of folding pipes are the gas hydrate formation units. The folding pipe hydrate formation units are composed of many U-type pipes, which are the main carrier of hydrate formation. The gas-liquid flow law in the U-type pipe has the great significance on gas hydrate formation. The gas-liquid two phase flow in a single U-type pipe has been simulated by Fluent, gas distribution rule and flow characteristics in the U-type pipe has been investigated. The range of the entrance gas volume fraction is 0.1～0.6. Calculation results show that there is a certain degree of mixture between gas and liquid in the former straight section. The gas and liquid began to layer in the front of bend, the gas and liquid stratified obviously in the process of bend. The gas and liquid began to mix in the later straight section, but the degree of mixture is lower than the former. The liquid and gas flow phenomenon is different with disparate gas volume fraction. The gas and liquid stratified more obviously in the bend with the higher gas volume fraction. The law that the gas and liquid have a better mixture when gas volume fraction change range is 0.2～0.4 has been found, which is beneficial to hydrate formation.

Shear-driven stability of a rigid particle in yield stress fluids

The stability of a rigid particle in yield stress fluids, comprised of soft particle glasses (SPGs), is investigated in shear flow under an applied external force, such as weight, using particle dynamics simulations. Results provide the critical force threshold, in terms of the dynamic yield stress and the flow strength, required to initiate sedimentation of the rigid particle over a wide range of shear rates and volume fractions. The streamlines of the SPGs show local disturbances when the rigid particle settles. The form of these disturbances is consistent with the microdynamics and microstructure response of the neighboring soft particles of the sedimenting rigid particle. Sedimenting particle induces non-affine displacement to the suspensions at low shear rates and high applied forces, while these dynamical events are localized and suppressed at high shear rates. Stability diagrams, which provide the conditions of the sedimentation of the rigid particle, are presented in terms of the applied force and the shear rate. These individual stability diagrams at each volume fraction map onto a universal stability diagram when the external force is scaled by the dynamic yield stress and shear rate with a ratio of the solvent viscosity to the low-frequency modulus of the SPGs.

Excess Molar Volume and Deviations in Viscosity of the Binary Liquid Mixtures Containing 1,3-Dioxolane + Alkanols at T = 298.15k

Thermodynamic and transport properties of liquid and liquid mixtures have been used to understand the intermolecular interactions between the components of the mixture. The sound velocity, density and viscosity of binary liquid mixtures are important from practical and theoretical point of view to understand the liquid theory. In the present study sound velocity, density and viscosity have been measured of binary mixtures of 1, 3-dioxolane with pentanol, hexanol, heptanol, octanol, nonanol and decanol over the entire range of mole fraction at 298.15K, and atmospheric pressure. From these experimental measurements the excess molar volume (V<sub>m</sub><SUP>E</SUP>), excess viscosity (η<SUP>E</SUP>), acoustic impedance (Z<SUP>E</SUP>) and excess adiabatic compressibility (β<sub>ad</sub><SUP>E</SUP>), have been calculated. The excess molar volume (V<sub>m</sub><SUP>E</SUP>), excess viscosity (η<SUP>E</SUP>), acoustic impedance (Z<SUP>E</SUP>) and excess adiabatic compressibility (β<sub>ad</sub><SUP>E</SUP>), have been analyzed in terms of interactions arising due to structural effect, charge-transfer complexes and dipole-dipole interaction between unlike molecules. These deviations have been correlated by a polynomial Redlich-Kister equation. The excess properties are found to be eighter negative or positive depending on the molecular interactions and nature of the liquid mixtures. Excess properties provide important information in understanding the solute-solvent interaction in a solution. The excess molar volume (V<sub>m</sub><SUP>E</SUP>), excess viscosity (η<SUP>E</SUP>), acoustic impedance (Z<SUP>E</SUP>) and excess adiabatic compressibility (β<sub>ad</sub><SUP>E</SUP>), values have been interpreted to terms of the nature of intermolecular interactions between constituent molecules of mixtures.

Computational study of energy separation in convergent-divergent vortex tube for different throat diameters, throat locations, inlet pressures, and working gas

This paper aims to improve the energy separation performance of vortex tube with a converging–diverging design of the hot tube. Three-dimensional computational fluid dynamic simulations are conducted to explore energy separation in a straight vortex tube (SVT) and in convergent-divergent vortex tubes (CDVT) with variations in throat diameter, throat position, inlet pressure, and working gas. Detail analysis of flow and temperature distributions reveal that flow is accelerated in the converging part of CDVT, which increases the transfer of shear work from the axial region to the peripheral region of CDVT compared to SVT, thereby producing significantly higher cold temperature separation in CDVT compared to SVT. CDVT with non-dimensional throat diameter of 0.40 is observed to produce the maximum value of cold temperature separation, which is up to 9 K (∼35 %) higher than the same obtained with SVT. Coefficient of performance of cooling obtained with this CDVT is found to be up to ∼ 30 % higher compared to SVT. When CDVT is operated with helium, ΔTc is found to have mean increment of 20 K (56 %) compared to SVT being operated with air. Overall, CDVT having non-dimensional throat diameter of 0.40, throat position in the middle of the hot tube, and operating with helium is recommended for obtaining maximum temperature separation performance in a wide range of cold mass fraction.

Discharging of Ramsdellite MnO2 Cathode in a Lithium-Ion Battery.

We report an application of our unbiased Monte Carlo approach to investigate thermodynamic and electrochemical properties of lithiated manganese oxide in the ramsdellite phase (R-MnO2) to uncover the mechanism of lithium intercalation and understand charging/discharging of R-MnO2 as a cathode material in lithium-ion batteries. The lithium intercalation reaction was computationally explored by modeling thermodynamically significant distributions of lithium and reduced manganese in the R-MnO2 framework for a realistic range of lithium molar fractions 0 < x < 1 in Li x MnO2. We employed interatomic potentials and analyzed the thermodynamics of the resultant grand canonical ensemble. We found ordered or semiordered phases at x = 0.5 and 1.0 in Li x MnO2, verified by configurational entropy changes and simulated X-ray diffraction patterns of partially lithiated R-MnO2. The radial distribution functions show the preference of lithium for homogeneous distributions across the one-dimensional 2 × 1 ramsdellite channels accompanied by alternating reduced/oxidized manganese ions. The occupation of the interstitial sites in the channels is correlated with the calculated voltage profile, showing a sharp voltage drop at x = 0.5, which is explained by the energy penalty of shifting lithium ions from stable tetrahedral to unstable octahedral sites. To facilitate this work, our in-house software, Knowledge Led Master Code (KLMC) was extended to support massive parallelism on high-performance computers.

Droplet Friction on Superhydrophobic Surfaces Scales With Liquid-Solid Contact Fraction.

It is generally assumed that contact angle hysteresis of superhydrophobic surfaces scales with liquid-solid contact fraction, however, its experimental verification has been problematic due to the limited accuracy of contact angle and sliding angle goniometry. Advances in cantilever-based friction probes enable accurate droplet friction measurements down to the nanonewton regime, thus suiting much better for characterizing the wetting of superhydrophobic surfaces than contact angle hysteresis measurements. This work quantifies the relationship between droplet friction and liquid-solid contact fraction, through theory and experimental validation. Well-defined micropillar and microcone structures are used as model surfaces to provide a wide range of different liquid-solid contact fractions. Micropillars are known to be able to hold the water on top of them, and a theoretical analysis together with confocal laser scanning microscopy shows that despite the spiky nature of the microcones droplets do not sink into the conical structure either, rendering a diminishingly small liquid-solid contact fraction. Droplet friction characterization with a micropipette force sensor technique reveals a strong dependence of the droplet friction on the contact fraction, and the dependency is described with a simple physical equation, despite the nearly three-orders-of-magnitude difference in liquid-solid contact fraction between the sparsest cone surface and the densest pillar surface.

Hybrid Core-Shell TiCN@SiO2 Nanoparticles in Percolation-Based Polyvinylidene Fluoride Dielectrics for Improved High-Voltage Capacitive Energy Storage.

Solid-state polymer dielectrics offer an exceptional dielectric breakdown, but require an enhanced energy density to be competitive with alternative electrolyte-based energy storage technologies. Therefore, this research introduces conductive titanium carbonitride (TiCN) nanoparticles in a polyvinylidene fluoride (PVDF) matrix to obtain flexible percolation-based nanodielectrics by ultrasonication-based suspension processing and hot pressing. Well-dispersed TiCN nanoparticles in PVDF were obtained for a wide range of filler volume fractions, and an exceptional peak in the dielectric constant equal to 1130 (0.1 Hz) and 29 (10 kHz) was observed near the percolation threshold (9.2 vol %). The enhanced dielectric constant was ascribed to massive interfacial polarization occurring, resulting from Maxwell-Wagner-Sillars (MWS) polarization and a nanocapacitor mechanism that are dominant at low and high frequencies, respectively. An improvement by 30% in the energy density (0.042 Wh kg-1) compared with the neat PVDF matrix was achieved for the PVDF/TiCN nanodielectrics. The first successful uniform deposition of a nanometer-thin (3 nm) silica (SiO2) shell via the Stöber process on TiCN nanoparticles significantly suppressed the dielectric losses near percolation for the PVDF/TiCN@SiO2 nanodielectrics by more than 1 order of magnitude while offering dielectric constants of 34 (0.1 Hz) and 10 (10 kHz). This study demonstrates the potential of hybrid (core-shell) percolation-based dielectrics for an improved capacitive dielectric performance by an integrated dielectric characterization approach that simultaneously optimizes the dielectric constant, loss tangent, breakdown strength, and energy density.

The HYENAS project: a prediction for the X-ray undetected galaxy groups

Abstract Galaxy groups contain the majority of bound mass with a significant portion of baryons due to the combination of halo mass and abundance (Cui 2024). Hence they serve as a crucial missing piece in the puzzle of galaxy formation and the evolution of large-scale structures in the Universe. In observations, mass-complete group catalogues are normally derived from galaxy redshift surveys detected through various three-dimensional group-finding algorithms. Confirming the reality of such groups, particularly in the X-rays, is critical for ensuring robust studies of galaxy evolution in these environments. Recent works have reported numerous optical groups that are X-ray undetected (see, e.g. Popesso et al. 2024), sparking debates regarding the reasons for the unexpectedly low hot gas fraction in galaxy groups. To address this issue, we utilise zoomed-in simulations of galaxy groups from the novel Hyenas project to explore the range of hot gas fractions within galaxy groups and investigate the intrinsic factors behind the observed variability in X-ray emission. We find that the halo formation time can play a critical role – we see that groups in halos that formed earlier exhibit up to an order of magnitude brighter X-ray luminosities compared to those formed later. This suggests that undetected X-ray groups are preferentially late-formed halos and highlights the connection between gas fraction and halo formation time in galaxy groups. Accounting for these biases in galaxy group identification is essential for advancing our understanding of galaxy formation and achieving precision in cosmological studies.

Simulation and Experimental Validation of a New Separator Design for a Wide Range of Gas Volume Fractions

Summary For downhole gas-liquid separation, it is crucial to maintain high separation efficiency across a wide range of inlet gas volume fractions. In this paper, we present a numerical investigation into the flow field characteristics and separation mechanism of a new gas-liquid separator that utilizes centrifugal and gravity separation methods. An experimental system was built to validate the accuracy of the numerical model, and the numerical results show similar characteristics with experimental data in phase distribution as well as separation efficiency. In addition, we examine the impact of various operational parameters on the separation performance in this study. The findings indicate that the separator is capable of achieving a separation efficiency of approximately 100% within the inlet gas volume fraction range of 40–80%. Furthermore, it is crucial to control the liquid level to ensure effective separation of gas from the water layer. Altering the inlet liquid flow rate and gas volume fraction has a direct influence on the water content of the gas outlet, resulting in a decrease in separation efficiency. Consequently, optimization of the upper region of the separator is necessary to improve the separation performance.

Numerical investigation of fluid flow and heat transfer of a nanofluid around two circular cylinders arranged in tandem in horizontal duct

In this study, two-dimensional unsteady laminar convective heat transfer from two isothermal cylinders arranged in tandem in horizontal duct has been numerically investigated. The numerical study is performed by solving the governing equations (continuity and momentum) and energy equations using a finite volume-based code ANSYS Fluent. The present study was conducted using nano sized copper particles suspended in water. The Prandtl number Pr of the resulting suspension being equal to 7. The range of solid volume fractions studied is and the flow Reynolds number is equal to 100.The spacing ratio of the two cylinders was varied from 2 to 5 while the blockage ratio was kept constant β=0.25. A detailed discussion has been provided regarding the variation of flow structure and the characteristics of flow, including total drag and lift coefficients, as a function of the dimensionless parametersIn order to visualize the flow and heat transport, streamlines, vorticity contours and isotherms were generated. In addition, the local and average Nusselt numbers for the upstream and downstream cylinders are calculated. The results demonstrate that the force coefficients, the wake structure behind the cylinders, and the Nusselt number are significantly influenced by the value of the spacing ratio and the volume fractions of nanoparticles. The results demonstrate a significant enhancement in heat transfer efficiency relative to the base fluid. The aforementioned improvement is more pronounced in the case of higher gap ratios and higher nanoparticle volume fractions.

Clinical Outcomes of Carbon Ion Radiation Therapy for Malignant Peripheral Nerve Sheath Tumors

Purposeto investigate outcome and toxicity of patients affected by malignant peripheral nerve sheath tumors (MPNSTs) treated with high-dose carbon ion radiotherapy (CIRT). Patients and methodswe retrospectively analyzed the outcome of 23 patients with MPNST treated between July 2013 and December 2020. Out of these, 13 patients (56.5%) had incompletely resected tumors, 8 patients (34.7%) experienced recurrence after surgery, and 2 patients (8.7%) had unresectable tumors. Before CIRT treatment, 4 patients underwent a second surgery after the first local recurrence (LR), and 1 patient underwent a third surgery for the second local relapse of disease. Six (26%) of patients received neoadjuvant chemotherapy. The most frequent tumor site was brachial plexus (N=9; 39.1%). In five patients (21.7%) neurofibromatosis type 1 (NF1) disorder was found, while 4 patients (17, 4%) had radiation-induced MPNST. The median CIRT prescribed total dose was 69.8 Gy [RBE] (range, 54-76.8) delivered in a median of 16 fractions (range, 15-22). Eleven patients (47.82%) were treated according to a sequential boost protocol with a median prescribed dose to CTV-LR of 45 Gy[RBE] (range, 41.4 – 54). ResultsAfter a median follow-up time of 23 months (range 3-100 months), the OS rates at 1-year and 2-year were respectively: 82.38%, 61.51%. The 1-year and 2-year LRFS rates were respectively: 65.07%, 48.80%; the 1-year and 2-year PFS rates were respectively: 56.37%, 40.99%. No patients showed acute or late Grade 4 toxicity or any treatment-related deaths. Ten patients (43.48%) reported acute toxicities of Grade ≥2: dermatitis in 6 patients, mucositis in 2 patients, peripheral neuropathy in 4 patients. Eight patients (34.78%) reported late toxicities of Grade ≥2, mainly due to loco-regional neuropathy. Conclusionshigh dose CIRT shows favorable local effect with acceptable toxicities in patients with gross residual and LR after surgery, or unresectable malignant peripheral nerve sheath tumors. Advanced treatment modalities such as particle therapy should be considered for MPNSTs.

Mineralocorticoid receptor antagonists in heart failure: an individual patient level meta-analysis

Mineralocorticoid receptor antagonists (MRAs) reduce hospitalisations and death in patients with heart failure and reduced ejection fraction (HFrEF), but the benefit in patients with heart failure and mildly reduced ejection fraction (HFmrEF) or heart failure and preserved ejection fraction (HFpEF) is unclear. We evaluated the effect of MRAs in four trials that enrolled patients with heart failure across the range of ejection fraction. This is a prespecified, individual patient level meta-analysis of the RALES (spironolactone) and EMPHASIS-HF (eplerenone) trials, which enrolled patients with HFrEF, and of the TOPCAT (spironolactone) and FINEARTS-HF (finerenone) trials, which enrolled patients with HFmrEF or HFpEF. The primary outcome of this meta-analysis was a composite of time to first hospitalisation for heart failure or cardiovascular death. We also estimated the effect of MRAs on components of this composite, total (first or repeat) heart failure hospitalisations (with and without cardiovascular deaths), and all-cause death. Safety outcomes were also assessed, including serum creatinine, estimated glomerular filtration rate, serum potassium, and systolic blood pressure. An interaction between trials and treatment was tested to examine the heterogeneity of effect in these populations. This study is registered with PROSPERO, CRD42024541487. 13 846 patients were included in the four trials. MRAs reduced the risk of cardiovascular death or heart failure hospitalisation (hazard ratio 0·77 [95% CI 0·72-0·83]). There was a statistically significant interaction by trials and treatment (p for interaction=0·0012) due to the greater efficacy in HFrEF (0·66 [0·59-0·73]) compared with HFmrEF or HFpEF (0·87 [0·79-0·95]). We observed significant reductions in heart failure hospitalisation in the HFrEF trials (0·63 [0·55-0·72]) and the HFmrEF or HFpEF trials (0·82 [0·74-0·91]). The same pattern was observed for total heart failure hospitalisations with or without cardiovascular death. Cardiovascular death was reduced in the HFrEF trials (0·72 [0·63-0·82]) but not in the HFmrEF or HFpEF trials (0·92 [0·80-1·05]). All-cause death was also reduced in the HFrEF trials (0·73 [0·65-0·83]) but not in the HFmrEF or HFpEF trials (0·94 [0·85-1·03]). With an MRA, the risk of hyperkalaemia was doubled compared with placebo (odds ratio 2·27 [95% CI 2·02-2·56]), but the incidence of serious hyperkalaemia (serum potassium >6·0 mmol/L) was low (2·9% vs 1·4%); the risk of hypokalaemia (potassium <3·5 mmol/L) was halved (0·51 [0·45-0·57]; 7% vs 14%). Steroidal MRAs reduce the risk of cardiovascular death or heart failure hospitalisation in patients with HFrEF and non-steroidal MRAs reduce this risk in patients with HFmrEF or HFpEF. None.

Experimental studies of H2/Ar plasma in a cylindrical inductive discharge with an expansion region

Abstract The electrical parameters of H2/Ar plasma in a cylindrical inductive discharge with an expansion region are investigated by a Langmuir probe, where Ar fractions range from 0% to 100%. The influence of gas composition and pressure on electron density, the effective electron temperature and the electron energy probability functions (EEPFs) at different spatial positions are present. In driver region, with the introduction of a small amount of Ar at 0.3 Pa, there is a rapid increase in electron density accompanied by a decrease in the effective electron temperature. Additionally, the shape of the EEPF transitions from a three-temperature distribution to a bi-Maxwellian distribution due to an increase in electron–electron collision. However, this phenomenon resulting from the changes in gas composition vanishes at 5 Pa due to the prior depletion of energetic electrons caused by the increase in pressure during hydrogen discharge. The EEPFs for the total energy in expansion region is coincident to these in the driver region at 0.3 Pa, as do the patterns of electron density variation between these two regions for differing Ar fractions. At 5 Pa, as the discharge transitions from H2 to Ar, the EEPFs evolved from a bi-Maxwellian distribution with pronounced low energy electrons to a Maxwellian distribution in expansion region. This evolve may be attributed to a reduction in molecular vibrational excitation reactions of electrons during transport and the transition from localized electron dynamics in hydrogen discharge to non-localized electron dynamics in argon discharge. In order to validate the experimental results, we use the COMSOL simulation software to calculate electrical parameters under the same conditions. The evolution and spatial distribution of the electrical parameters of the simulation results agree well with the trend of the experimental results.

Application of bionic topology to latent heat storage devices

Latent heat storage is employed to address the intermittent supply of renewable energy, and enhancing heat transfer in phase change materials (PCMs) is pivotal for achieving effective heat storage. Currently, the predominant method for improving heat transfer is through the integration of high thermal conductivity fins into heat storage devices. This study introduces an innovative design of a three-tube phase change heat storage device created through bionic topology optimization. The impact of parameters such as penalty factors and filtering radius on the topology structure is analyzed, and the optimal range of fin volume fraction is determined based on energy storage density and energy storage time. Considering the influence of natural convection on heat transfer properties, four distinct heat storage models, including topology-optimized fins, are compared. The heat transfer and flow properties during the processes of melting and solidification, as well as their field synergy, are investigated. The study reveals that the optimized fins exhibit more bionic fractal structures and a larger, more uniform heat transfer contact area. Compared to traditionally optimized fin structures, this research reduces the heat storage time of the three-tube heat storage device by 21.96 % and the heat release time by 38.13 % without compromising the maximum heat storage capacity. The topology-optimized fins demonstrate a fractal dimension similar to natural fractal structures such as branches, leaf veins, antlers, and snowflakes. This study presents a novel bionic structural design approach for high-performance latent heat storage systems.

Porous Structure Enhances the Longitudinal Piezoelectric Coefficient and Electromechanical Coupling Coefficient of Lead-Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3.

The introduction of porosity into ferroelectric ceramics can decrease the effective permittivity, thereby enhancing the open circuit voltage and electrical energy generated by the direct piezoelectric effect. However, the decrease in the longitudinal piezoelectric coefficient (d33) with increasing porosity levels currently limiting the range of pore fractions that can be employed. By introducing aligned lamellar pores into (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3, this paper demonstrates an unusual 22-41% enhancement in the d33 compared to its dense counterpart. This unique combination of high d33 and a low permittivity leads to a significantly improved voltage coefficient (g33), energy harvesting figure of merit (FoM33) and electromechanical coupling coefficient ( ). The underlying mechanism for the improved properties is demonstrated to be a synergy between the low defect concentration and high internal polarizing field within the porous lamellar structure. This work provides insights into the design of porous ferroelectrics for applications related to sensors, energy harvesters, and actuators.

Drop Retention and Departure in Adiabatic Shear Flow on Structured Superhydrophobic Surfaces.

Drops are retained or held on surfaces due to a retention force exerted on the drop by the surface. This retention force is a function of the surface tension of the liquid, drop geometry, and the contact angle between the drop and the surface. When external or body forces exceed the retention force, the drop begins to move. This work explores the conditions for which drop departure occurs on structured superhydrophobic surfaces in the presence of an applied shear flow. Drop departure is explored for five microstructured superhydrophobic surfaces, one nanostructured carbon nanotube surface and one smooth hydrophobic surface. Surface solid fractions range from 0.05 to 1.00, and measured static contact angles range from 121° to 161°. Droplet volumes of 5, 10, 20, 30, 40, and 50 μL are tested on each surface. For each experiment, increasing air velocity is applied to a droplet placed on a surface until the droplet departs. High-speed imaging is used to track droplet base length, height, cross-section area (as viewed from the side) and advancing/receding contact angles. Measurements of drop advancing and receding contact angles are reported at the point of departure, with increasing contact angle hysteresis observed prior to departure. Contact angle hysteresis is observed to be a good indicator of droplet mobility. Measurements of the average air velocity over the height of the droplet are determined at the point of departure for all conditions. The measured air velocity shows strong dependence on the surface solid fraction, and the required shear flow velocity decreases as the surface solid fraction decreases. This is most pronounced at very low solid fractions. A coefficient of drag for the departing drops in shear flow is calculated and is shown to decrease with increasing Reynolds number.

Experimental Study of the Effect of CO/H2 Ratio and Release Pressure on Syngas Jet Flame Propagation and Overpressure.

Syngas, composed of hydrogen and carbon monoxide, serves as an alternative fuel for hydrogen energy and a key raw material for chemical synthesis. However, due to its flammable nature, syngas poses risks of forming explosive mixtures in the event of a leak. This study explores potential accident scenarios in coal chemical environments involving syngas reaction vessels. Experimental investigations focus on the overpressure and propagation dynamics of jet flames resulting from syngas leakage, with CO volume fractions ranging from 50 to 80% and release pressures between 2 and 5 MPa. Results reveal that maximum flame overpressure occurs within a CO volume fraction range of 55-65%, with no consistent relationship observed between overpressure and CO fraction at fixed release pressures. During our experiments, the maximum recorded overpressure of 28.4 kPa was reached during vented explosions. Additionally, ignition outcomes categorize into three types based on flame propagation speed: combustion/flare, resembling normal deflagration; and high-velocity deflagration, characterized by rapid propagation and potential for steady jet fire formation. While shockwave-like features may be observed, these do not indicate true detonation. These findings offer insights for the safe handling and storage of syngas.

Deep neural network homogenization of multiphysics behavior for periodic piezoelectric composites

We present a physically informed deep neural network homogenization theory for identifying homogenized moduli and local electromechanical fields of periodic piezoelectric composites. The theory employs a multi-network model to represent solutions to stress equilibrium and electrostatic partial differential equations in the inclusion and the matrix phases, leading to a more accurate depiction of field variables. Satisfaction of periodicity conditions for hexagonal and cubic symmetries are efficiently tackled using a series of sinusoidal functions with known periods and adjustable parameters. Additionally, the theory applies fully trainable weights to the collocation points. These trainable weights, trained concurrently with the neural network weights, compel the neural networks to enhance their performance when faced with large local stress/deformation gradients. The predictive capability of the proposed theory is illustrated by comparison with finite-element solutions for composites reinforced with unidirectional fiber, spherical particle, or weakened by an ellipsoidal cavity over a wide range of volume fractions.

Attaining Tailored Wicking Behavior with Additive Manufacturing.

Additive manufacturing (AM) has opened a new pathway to create customized wicking materials. With lower manufacturing costs and a larger design space than many alternatives for wicking, AM is of particular value in fields such as thermal management and microfluidics. Fluid propagation during wicking in porous media, however, has largely remained limited to Washburnian () behavior, and optimizing these materials for wicking in a variety of use cases presents a challenge. In this work, we present a method of tailoring wicking behavior to an arbitrary target function of propagation distance versus time, achieved through the use of AM to create nonuniform porous materials. Layers of parallel lines, each successive layer rotated 90° from the last, form a gridded structure with a spatially varying unit cell size for which analytical models for the capillary pressure and solid fraction and a semianalytical model for permeability were found. These models were validated with capillary rise experiments for spatially uniform porous materials over a range of solid fractions from 0.4 to 0.9. Leveraging these models and representing a nonuniform porous material as a series of Ohmic fluidic resistors, we created an inverse design algorithm that generates a wicking material with spatially varying parameters to achieve a specified target function for fluid propagation as a function of time. These materials can exhibit atypical wicking behavior, including fluid propagation displaying simple linear and piecewise linear relationships with time rather than the conventional Washburn relationship.

Computational investigation of the role of ventricular remodelling in HFpEF: The key to phenotype dissection

Recent clinical studies have reported that heart failure with preserved ejection fraction (HFpEF) can be divided into two phenotypes based on the range of ejection fraction (EF), namely HFpEF with higher EF and HFpEF with lower EF. These phenotypes exhibit distinct left ventricle (LV) remodelling patterns and dynamics. However, the influence of LV remodelling on various LV functional indices and the underlying mechanics for these two phenotypes are not well understood. To address these issues, this study employs a coupled finite element analysis (FEA) framework to analyse the impact of various ventricular remodelling patterns, specifically concentric remodelling (CR), concentric hypertrophy (CH), and eccentric hypertrophy (EH), with and without LV wall thickening on LV functional indices. Further, the geometries with a moderate level of remodelling from each pattern are subjected to fibre stiffening and contractile impairment to examine their effect in replicating the different features of HFpEF. The results show that with severe CR, LV could exhibit the characteristics of HFpEF with higher EF, as observed in recent clinical studies. Controlled fibre stiffening can simultaneously increase the end-diastolic pressure (EDP) and reduce the peak longitudinal strain (ell) without significant reduction in EF, facilitating the moderate CR geometries to fit into this phenotype. Similarly, fibre stiffening can assist the CH and ‘EH with wall thickening’ cases to replicate HFpEF with lower EF. These findings suggest that potential treatment for these two phenotypes should target the bio-origins of their distinct ventricular remodelling patterns and the extent of myocardial stiffening.