Wall Energy Research Articles

A thermodynamic model of a rapid compression expansion machine applied for the estimation of the flame speed of air/hydrogen mixtures

This work presents a thermodynamic inverse model to extract the main flame propagation characteristics of an ultra-lean air/hydrogen mixture burning in a rapid compression/expansion machine (RCEM). Differently from combustion vessels, RCEMs allow fundamental combustion studies under thermodynamic conditions of temperature and pressure relevant to internal combustion engine (ICE) operations.The presented thermodynamic model takes into account all the main phenomena occurring in an RCEM, such as the wall heat transfer, and mass, species, and energy exchange with the crevice volumes. Moreover, combining the inverse model with a simplified geometrical description of the flame front, the flame propagation velocities are derived from experimental data of pressure and piston position.The model is applied to investigate the combustion process of a hydrogen/air mixture with λ between 2.1 and 2.6 and thermodynamic states relevant to ICE operations (initial pressure and temperature of around 30 bar and 720 K, respectively). The methodology is validated against direct measurements of flame front velocities realized by optical access in the combustion chamber. The model and measurements underline that the flame speed related to the unburned gas progressively decreases as λ increases, passing from 4.4 m/s at λ = 2.1 down to 2.5 m/s at λ = 2.6. The model/experiment RMSE on the absolute flame velocity is of 0.6 m/s over twelve test points, supporting the consistency of the presented thermodynamic model.

Hysteresis Behavior of Hybrid Rocking Walls: An Analytical Method

This study proposed an analytical method to predict the hysteresis behavior of hybrid rocking walls (HRWs) in the two limit states of decompression and geometric nonlinearity. The flag-shaped curve of a HRW under a given cyclic load was described using the parameters of initial stiffness, post-yield stiffness, and the energy dissipated by the wall energy dissipaters. In this method, the hysteresis loops of the wall were determined assuming no tendon yielding and concrete crushing at the wall toes. The results of the proposed analytical method were validated via experiments on two HRWs under cyclic loads and previously validated finite element models. Comparing the results of the analytical method with those of the tests and numerical models showed that the proposed method can provide acceptable predictions for the yield point, ultimate point, initial and post-yield stiffnesses, energy dissipation level in each loading cycle, as well as the hysteresis behavior of hybrid walls. This showed the efficiency and accuracy of the proposed analytical method. Moreover, despite the simplifying assumptions, the good agreement between the analytical approach and experimental hysteresis loops indicated that the role of plastic deformation in energy dissipation at the bottom of HRWs is negligible.

Flourishing Antibacterial Strategies for Osteomyelitis Therapy.

Osteomyelitis is a destructive disease of bone tissue caused by infection with pathogenic microorganisms. Because of the complex and long-term abnormal conditions, osteomyelitis is one of the refractory diseases in orthopedics. Currently, anti-infective therapy is the primary modality for osteomyelitis therapy in addition to thorough surgical debridement. However, bacterial resistance has gradually reduced the benefits of traditional antibiotics, and the development of advanced antibacterial agents has received growing attention. This review introduces the main targets of antibacterial agents for treating osteomyelitis, including bacterial cell wall, cell membrane, intracellular macromolecules, and bacterial energy metabolism, focuses on their mechanisms, and predicts prospects for clinical applications.

Bamboo-inspired strong, tough and stable composites derived from renewable bamboo

Bamboo engineering materials are made from abundant raw material sources and can be easily prepared with minimal processing and low pollution. However, when used as structural materials, they are limited by their weight, strength, and lack of stable designability. The use of laminated structure and a gluing interface are key factors affecting the performance of bamboo engineering materials. Bamboo exhibits excellent toughness and strength when resisting external forces, with a multi-level interlocking reinforced interface with bamboo’s intercellular layer that induces an increase in crack deflection paths (internal toughening) and cell wall energy consumption (external toughening) coupled to microfibril pulling out. Inspired by the functionally graded structure of the lightweight and high-strength bamboo wall layer and the interlocking reinforced interface between vascular bundles and parenchyma cells, we designed a high-performance bamboo engineering material designed to imitate bamboo, Imitation Bamboo Bundle Laminated Veneer Lumber (IBLVL), prepared by uniform lamination and gradient molding. The designed IBLVL is light in weight, with high strength and uniform density. This work demonstrates the feasibility of using resource-rich and sustainable bamboo to manufacture light-weight bamboo engineering materials with high strength and high toughness that can be substituted for non-renewable resources in the fields of construction and transportation.

Insight into the evolutions of microstructure and performance in bismuth ferrite modified potassium sodium niobate lead-free ceramics

In consideration of growing human health and ecological environment issues, lead-free piezoelectric ceramics have aroused heated research to develop their potential applications in electronic fields instead of toxic lead-based ones. In the present work, a ternary lead-free material system of (0.97- x )K 0.48 Na 0.52 Nb 0.96 Sb 0.04 O 3 –0.03Bi 0.5 Na 0.5 Zr 0.8 Sn 0.2 O 3 - x BiFeO 3 (KNNS-BNZS- x BF, 0 ≤ x ≤ 0.007) ceramics was designed, and the evolution mechanisms of microstructures and electrical behaviors at multiple applied fields were revealed in detail. The bimodal microstructure with an alternative fine and coarse grain size distribution feature is generally observed, while the BF doping tends to decrease grain size and increase the diffusion phase transition behaviors. As x = 0.005, the R-O-T multiphase boundary is formed at room temperature, accompanied by the presence of striped nanodomains with smaller size and regular distribution feature that exhibit the better polarization switching and the fast domain wall movement under external stimuli. In particular, an enhanced d 33 ~ 470 pC/N and a simultaneous higher T c ~ 260 °C are achieved in KNNS-BNZS-0.005BF, reflecting a better balanced development of performance by the present doping strategy. Most importantly, benefiting from the coexistence of R-O-T multiphase boundary and the lower domain wall energy, an excellent d 33 ⁎ ~ 530 pm/V is attained as well in this ceramic, which favors the better applications in high precision displacement or strain actuators. This work sheds insight into understanding the underlying physical mechanism of enhanced performance of KNN-based ceramics, substantially expanding the more applications of lead-free piezoelectric materials in electronic fields. • A new lead-free material system of KNNS-BNZS- x BF is designed. • Enhanced comprehensive performance is obtained by constructing R-O-T multiphase boundary. • The domain structures and polarization switching behaviors are revealed in detail. • The physical origin of enhanced performance is elaborated.

Enhancement of skyrmion density via interface engineering

Magnetic skyrmions are promising candidates for computing and memory applications. The static and dynamic behaviors of skyrmions are tunable by altering the interfacial magnetic properties. These interfacial magnetic properties are alterable by modifying the interface structure of thin films. However, the relationship between the structural properties of the interface and the skyrmions properties is not straightforward, and a comprehensive insight is required to facilitate better controllability of the skyrmions’ behaviors. Here, we comprehensively understand the relationship between atomic displacements at the interface and skyrmions’ static behavior. In this study, we used ion irradiation to achieve inter-atomic displacements. We observed that the inter-atomic displacements could tailor the physical properties of skyrmions. We noticed a peculiar increase in the magnetization, Dzyaloshinskii–Moriya interaction, and exchange stiffness. The modifications in magnetic properties reduced the domain wall energy, which enhanced the skyrmion density (by six-folds) and reduced the average skyrmion diameter (by 50%). Furthermore, we compared the observed results of ion irradiation with those from the annealing process (a well-studied method for modifying magnetic properties) to better understand the effect of atomic displacements. Our study provides a route to achieve a highly-dense skyrmion state, and it can be explored further to suppress the skyrmion Hall effect for skyrmion-based applications.

Computational Fluid Dynamics Analysis of Blood Flow Changes during the Growth of Saccular Abdominal Aortic Aneurysm.

Computational fluid dynamics analysis of the growth process of saccular abdominal aortic aneurysm was performed. A 3D model of aortic aneurysm was created based on CT images. Properties in terms of wall shear stress, mean flow velocity, mean pressure, energy loss, and pressure loss coefficient were calculated using thermal fluid analysis software "ANSYS CFX." As the aneurysm expanded, the mean flow velocity decreased and the wall shear stress, mean pressure, energy loss, and pressure loss coefficient increased. Wall shear stress increased when the aneurysm was small, suggesting that is related to the development and growth of the aneurysm. (This is secondary publication from J Jpn Coll Angiol 2021; 61: 3-10.).

Regulation of Cell Wall Degradation and Energy Metabolism for Maintaining Shelf Quality of Blueberry by Short-Term 1-Methylcyclopropene Treatment

In order to study a short-term and efficient technology by 1-methylcyclopropene (1-MCP) in blueberry, the fruit was treated with 0, 0.5, 1 and 3 μL/L 1-MCP for 2 h then stored at 25 ± 1 °C with 40–50% relative humidity (RH) for 9 d. The weight loss, decay incidence, respiration rate, firmness, soluble solid content (SSC), titratable acid (TA), Brix-acid ratio (BAR), sensory evaluation, content of cell wall polysaccharide, activities of cell wall composition-related enzymes and energy metabolism in blueberry were determined during shelf life. The results showed that the weight loss, decay incidence and respiration rate were reduced by 3 μL/L 1-MCP treatment. Compared to other groups, the firmness, the content of TA and anthocyanins were maintained in 3 μL/L 1-MCP-treated blueberry. In contrast, the SSC and BAR were lower compared to those untreated. However, the sensory evaluation of “taste” and “aroma” value showed no differences in all fruits. The content of protopectin, cellulose and hemicellulose was higher in 1-MCP-treated blueberry, accompanied by a decrease in polygalacturonase (PG) and pectin methyl esterase (PME) activity. The content of water-soluble pectin (WSP) was lower in 1-MCP-treated blueberry than untreated ones. The activity of phenylalanine ammonia lyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate-CoA ligase (4CL) was higher in 1-MCP-treated blueberry than the untreated, which induced more serious lignification. The results of energy metabolism also showed that the 1-MCP treatment could ensure sufficient intracellular energy supply. The 3 μL/L 1-MCP treatment could maintain the shelf quality and retard decomposition of cell wall polysaccharide by ensuring sufficient intracellular energy supply and inhibiting cell wall-degrading enzymes activity. Taken together, this study highlighted an efficient and short-term 1-MCP treatment technique.

Soret Dissipation Effect On Heat And Mass Transmission Of Non-Newtonian Casson Radiative Nanofluid Flow With Lorentz Drag And Rosseland Radiation

The goal of the current study considers the impact of Lorentz force and radiation on the reactive Casson-Nanofluid flow over a flow over a stretched surface with Soret impact. However, its industrial and technological applications are numerous but not limited to solar power, glass spinning, nuclear reactors, processing and packaging of food, etc. The flow being considered is a function of the stretched surface along its direction in line with a linearly changing velocity with such distance from a given immovable point. The partial differential equations describing the momentum, energy (heat) and mass transfer equations were transformed into non-linear ordinary differential equations in non-dimensional forms through the use of the similarity variables approach. The solution which was carried out through the application of the series approximation method is presented analytically. However, the Mathematica software was used in obtaining the numerical solutions. Thus, the impacts of physical parameters of the fluid were studied. The results indicated that: the velocity of fluid flow lessens due to the combined intensification of values of the non-Newtonian Casson fluid and magnetic field parameters. An upsurge in Grashof heat and radiation factors yields a rise in the velocity. Influence of collective Casson and magnetic parameters leads to an appreciation of heat distribution. Also, the concentration field declines as both the Casson and Schmidt parameters improve. The diminishing distribution fields of both the wall energy and mass gradients are functions of the appreciating values of the non-Newtonian number.

Cyclic Behavior of Multiple Hardening Precast Concrete Shear Walls

Precast Concrete (PC) shear walls are becoming popular in building structures. With “wet” connection techniques, PC shear walls often behave like conventional cast-in-place walls, where hardening occurs after yielding. In this study, two PC shear walls assembled by the “dry” connection technique, and one cast-in-place shear wall, were tested by means of quasi-static cyclic loading. The main purpose of the experiment was to systematically investigate the cyclic response of PC shear walls with varying types of vertical connection in the form of a friction-bearing device. The results showed that vertical bearing in devices, which mainly stems from the longitudinal elongation of PC wall panels, could enlarge the axial force of end column so that it provided an additional resistance moment. The PC shear wall with weak connection achieved ductile failure and second ascending branches on load-displacement relationship, i.e., secondary hardening, and the wall with strong vertical connection performed great moment capacity as well as tertiary hardening. Compared to cast-in-place walls, the peak load and cumulative hysteretic energy of PC shear walls increased by about 60% and 100%, respectively. A conceptual analysis of the multiple hardening phenomenon is presented based on experimental results.

Beryllium melt instabilities and ejection during unmitigated current quenches in ITER

The dynamics of transient liquid beryllium flows induced on the ITER first wall during the current quench stage of unmitigated vertical displacement events are modelled by means of two-dimensional Navier–Stokes simulations. The study focuses on melt that is driven to the first wall panels’ chamfered edges, where free-surface instabilities are the most likely to be seeded. Beyond their impact on plasma-facing component damage, these instabilities potentially result in material ejection in the form of droplets, which may ultimately solidify into dust and accumulate in the vessel. Based on prior integrated numerical predictions of quenching magnetic equilibria, wall energy deposition and melt-related damage in a concrete worst-case disruption scenario, the simulations suggest that, although the liquid layer is significantly destabilized, only 5% of the total melt mass created on the wall surface is lost through ejection. This result can serve as a basis to refine the estimates of the real transient-induced beryllium dust inventory expected in ITER.

Influence of stress-induced anisotropy on domain structure and magnetic properties of Fe-based nanocrystalline alloy under continuous tension annealing

The correlation among microstructures, magnetic properties and domain patterns for the FINEMET nanocrystalline ribbons treated in a home-made continuous tension annealing equipment under different tensile stresses (σ) were investigated in detail. Results show that the effective permeability (μe) of the nanocrystalline ribbons can be expediently adjusted from 412.83 to 1659.96 by manipulating the magnitude of stress-induced anisotropy constant (Ku), wherein the Ku and σ are in a linear relationship. Owing to the increasing domain wall energy induced by the increase of σ for the nanostructured ribbons, the attenuation of μe with the elevating applied field and frequency can be effectively suppressed, the average domain width between the strip-like domain patterns gradually decreases, and the domination of magnetization process alters from domain-wall displacement to homogeneous rotation. These results will provide a referable idea for current transformers to meet the requirements of higher precision and lower energy consumption.

Transpiration effect on Falkner-Skan bioconvective mixed nanoliquid flow above a poignant wedge

Numerical computations are executed to investigate the consequence of the Buongiorno slip mechanism and radiative heat on gyrotactic microorganisms containing Casson cross nanoliquid flow across a moving wedge. The mixed nanofluid comprises magnesium and copper oxide (MgO and CuO) nanoparticles pondered in water. The bioconvection Falkner-Skan flow governing equations are resolved using the BVP5C Matlab package. Simultaneous solutions are drawn for suction and injection cases. Plots illustrate the effect of pertinent physical factors on flow, thermal, diffusion, and motile organism density. The wall friction, energy rate, and mass transmission are interpreted via tables. The outcomes reveal that the consequence of embedded features on the bioconvective mixed nanoliquid stream are substantial in the suction case as matched with injection case. The deposition of MgO and CuO nanomaterials raises the heat transmission of the base liquid to a more significant level. Further, the Buongiorno slip mechanism parameter intensifies the thermal outlines and decays the energy transport rate for suction/injection cases. The major applications of current investigation can be found in geothermal energy systems.

Global Methylation Analysis Using MSAP Reveals Differences in Chilling-Associated DNA Methylation Changes during Dormancy Release in Contrasting Sweet Cherry Varieties

Dormancy is an adaptive strategy developed by temperate perennial crops to protect overwinter tissues from unfavorable environmental conditions. Sweet cherry (Prunus avium L.), a member of the Rosaceae family, requires chilling to overcome dormancy. The time of harvest is directly correlated with chilling requirements in sweet cherries. Consequently, early and late season varieties have low and high chilling requirements, respectively. There is evidence that the expression of dormancy-related genes is regulated by DNA methylation. In this work, methylation-sensitive amplified polymorphism (MSAP) was applied to study genome-wide DNA methylation changes associated with dormancy in two low-chill varieties, ‘Royal Dawn’ and ‘Glen Red’, and one high-chill variety, ‘Kordia’. Our primary results suggest that the occurrence of progressive DNA demethylation is associated with chilling accumulation during dormancy in the three varieties, independent of their chilling requirements. Genes were identified with different methylation status changes, detected by MSAP, related to cell wall remodeling and energy metabolism. Several MSAP profiles among the varieties were observed, suggesting that fine epigenetic control is required to coordinate hormonal and environmental signals that induce dormancy and its release.

Mechanically tunable elastic modulus of freestanding Ba1−xSrxTiO3 membranes via phase-field simulation

The freestanding ferroelectric membranes with super-elasticity show promising applications in flexible electronic devices such as transducers, memories, etc. While there have been recent studies on the effect of mechanical bending on the domain structure evolutions and phase transitions in ferroelectric membranes, its influence on Young's modulus of these freestanding membranes is less explored, which is crucial for the design and application of flexible electronics. Here, a phase-field model is developed to simulate the tunability of Young's modulus of freestanding Ba1−xSrxTiO3 membranes under mechanical bending. It is demonstrated that the bended membrane shows a uniform Young's modulus compared with unbended membrane. By increasing the bending angle, Young's modulus tunability is enhanced, which can be attributed to the vortex-like domain structures induced by the mechanical bending. These vortex-like domains with large domain wall energy inhibit the subsequent domain switching under externally applied tensile strain and reduce the eigenstrain variation, which leads to a large Young's modulus. In addition, the formation of vortex domain structure is suppressed with increasing Sr2+ content in Ba1−xSrxTiO3 membranes at the same bending degree, resulting in a decrease in Young's modulus tunability. Our work reveals that the tunability of Young's modulus of freestanding ferroelectric membranes can be achieved by mechanical bending, which provides guidance for designing flexible electronic devices.

The achieving enhanced piezoelectric performance of KNN-based ceramics: Decisive role of multi-phase coexistence induced by lattice distortion

Multi-phase coexistence induced by phase boundary regulation is an efficient approach to promote the performance of (K, Na)NbO3 ceramics. Here, [(1-x) (K0.5Na0.5)(Nb0.965Sb0.035)O3 - x (Bi0.5Na0.5)HfO3, x = 0, 0.01, 0.02, 0.03, 0.04, 0.05] [(1-x) KNNS - x BNH] lead-free piezoceramics are prepared through solid-state sintering method. The changes of internal phase structure are analysed by systematic measurements, from which the coexistence of rhombohedral-tetragonal (R-T) multi-phase is confirmed at x = 0.04. The lattice distortion caused by BNH doping induces the coexistence of R-T multi-phase, consequently achieving the best comprehensive properties at x = 0.04 (d33 = 353 pC/N, TC = 285 ℃, εr = 6517, Pr = 15.3208 μC/cm2), which is due to the reduced domain wall energy and more easily deflected domains in the R-T multi-phase coexistence zone. This work is helpful to understand the essence of the multi-phase coexistence caused by doping to improve the piezoelectric performance.

Efficient Inner-to-Outer Wall Energy Transfer in Highly Pure Double-Wall Carbon Nanotubes Revealed by Detailed Spectroscopy.

The coaxial stacking of two single-wall carbon nanotubes (SWCNTs) into a double-wall carbon nanotube (DWCNT), forming a so-called one-dimensional van der Waals structure, leads to synergetic effects that dramatically affect the optical and electronic properties of both layers. In this work, we explore these effects in purified DWCNT samples by combining absorption, wavelength-dependent infrared fluorescence-excitation (PLE), and wavelength-dependent resonant Raman scattering (RRS) spectroscopy. Purified DWCNTs are obtained by careful solubilization that strictly avoids ultrasonication or by electronic-type sorting, both followed by a density gradient ultracentrifugation to remove unwanted SWCNTs that could obscure the DWCNT characterization. Chirality-dependent shifts of the radial breathing mode vibrational frequencies and transition energies of the inner and outer DWCNT walls with respect to their SWCNT analogues are determined by advanced two-dimensional fitting of RRS and PLE data of DWCNT and their reference SWCNT samples. This exhaustive data set verifies that fluorescence from the inner DWCNT walls of well-purified samples is severely quenched through efficient energy transfer from the inner to the outer DWCNT walls. Combined analysis of the PLE and RRS results further reveals that this transfer is dependent on the inner and outer wall chirality, and we identify the specific combinations dominant in our DWCNT samples. These obtained results demonstrate the necessity and value of a combined structural characterization approach including PLE and RRS spectroscopy for bulk DWCNT samples.

First-principles calculations of domain wall energies of prototypical ferroelectric perovskites

Ferroelectric domain walls play a critical role in determining the polarization switching kinetics and physical properties in ferroelectric materials. There have been extensive studies on identifying the domain wall structures and domain wall energies. Nevertheless, the predicted domain wall energies tend to vary a lot for the same type of domain walls, and it remains elusive under what conditions the non-Ising type domain wall is more stable than the Ising type. In this work, we performed first-principles calculations to evaluate the structures and energetics of several types of domain walls for two prototypical tetragonal ferroelectric perovskites, PbTiO3 and BaTiO3, including charge-neutral 90° domain walls, Ising-type and Ising-Bloch-type 180° domain walls with various orientations. We adopted three schemes of structural optimization to optimize the domain wall structures and extract the domain wall energies by carefully eliminating the contribution from strain energies. We discussed how the choice of the schemes influence the calculation results and their applicable conditions. We found that the anisotropy of domain wall energy for Ising-type 180° walls is larger in BaTiO3 than that in PbTiO3. The emergence of Bloch component in PbTiO3 can lower the domain wall energy and reduce its anisotropy. This work offers a more accurate method for predicting the domain wall structures and energetics of ferroelectrics. The calculation results can be useful for understanding of stability of ferroelectric domain walls with high-index orientations and non-Ising characteristics, which is of critical importance in developing domain wall nanoelectronics.

Effect of insulation thickness on energy saving in cold regions of Türkiye

In the countries procuring a major amount of their energy from abroad, using of the energy effectively and ensuring the energy-saving become gradually more important. In this study, considering the climatic and meteorological conditions of Van province, optimum insulation thickness, payback period, and energy-saving values were analyzed for three insulation materials (rock wool, polyurethane, XPS) and five energy sources (imported coal, fuel oil, LPG, natural gas and electricity) on wall models built with pumice and aerated concrete. The optimum insulation thickness was calculated using the interest and inflation rates. The calculations were made by making use of the lifecycle cost analysis (LCCA). Insulation thickness that should be applied depending on the wall elements used in buildings can vary. Thus, examining the wall models, insulation materials and energy sources were examined, and the optimum insulation thicknesses, annual savings, and payback periods were found to be 3-15.6 mm, 30-63%, and 1.4-5.8 years, respectively, in the present study.

The assessment of an acoustic Doppler velocimetry profiler from a user’s perspective

Acoustic Doppler velocimetry profilers (ADVPs) are widely used in both experimental and field studies because of their robustness in velocity measurements. The acquired measurements do not only offer estimates of the local and instantaneous flow velocity at the interrogated measurement volume, but can also be further processed for the estimation of the bed surface shear stresses, thus they are finding a wide range of applications ranging from water engineering to geomorphology and eco-hydraulics. This study aims to evaluate the performance of an ADVP in obtaining hydrodynamics measurements under fixed flow conditions, with various probe configurations. To this goal, a robust search is conducted where ADVP probe settings are sequentially altered. A number of assessment criteria are used including qualitative observations, such as checking the shape of the velocity profile, as well as quantitative error metrics, including signal-to-noise ratio, correlations and number of spikes. Further, estimation of the bed shear stresses computed by means of using the log Law of the Wall and turbulent kinetic energy, allow obtaining a better understanding of the uncertainties involved and the importance of making a better informed choice with respect to the probe configuration settings. Thus, the methodology and performance metrics provided herein, although presented for a given flow, can generally be applied from practitioners and researchers alike.