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The Brazilian electrical system (BES) relies heavily on hydrothermal energy, specifically hydroelectric power plants (HPPs), which are highly dependent on rainfall patterns. The São Francisco River Basin (SFRB) is a critical component of the BES, playing a key role in electricity generation. However, climate extremes have increasingly impacted energy production in recent decades, posing challenges for HPP management. This study, explores the relationship between extreme precipitation events in the SFRB and two crucial energy variables: Stored Energy (STE) and Affluent Natural Energy (ANE). We analyze the spatial distribution and trends of 11 extreme precipitation indices and investigate the seasonality, trends, and correlations between these energy variables and the extreme indices. Our findings reveal downward trends in both ANE and STE. Additionally, we identify a seasonal pattern influenced by extreme precipitation rates at various time scales. The results indicate that it is possible to estimate ANE and STE efficiently by employing three machine learning (ML) algorithms (Random Forest, Artificial Neural Networks and k-Nearest Neighbors) using extreme precipitation data. These results offer valuable insights for the strategic planning and management of the BES, aiding in decision-making and the development of energy security. [ABSTRACT FROM AUTHOR]

Fatigue behavior is intrinsically linked to microstructural alterations induced by cyclic loading. However, the quantification of microstructural defects associated with fatigue damage of NiTi shape memory alloys (SMAs) is lacking, which hinders the development of a physically based fatigue criterion. To this end, a multi-scale experimental analysis was conducted on cyclically deformed NiTi SMAs, which evidenced a strong correlation between microstructural inhomogeneity and localized deformation behavior. The microstructural change associated with fatigue was quantified in terms of stored strain–energy, with the highest values observed in the regions where fatigue cracks initiate. Consequently, stored energy is deemed as an effective fatigue indicator, offering valuable insights for future work in the design and optimization of SMAs’ structures against fatigue.

The microstructure evolution of the wrought superalloy GH4698 bar subjected to annealing was investigated during solution treatment, with managing temperature and duration. The differences in mechanical properties between the core and the edge of annealed rod are attributed to residual stresses introduced by surface grinding in the shallow layers of the bar. Experimental findings of heat treatment revealed that grains in the core of the bar grow normally, with the average size exhibiting exponential growth with respect to the solution temperature and time. Abnormally large grains (ALGs) were observed at the edge of the rod under sup-solvus temperature. The presence of γ′ can restrict grain growth, but the dissolution of γ′ is not the fundamental cause leading to the occurrence of abnormal grain growth (AGG). The initial reason for AGG at the edge position lies in the presence of stored energy (SE). Grains undergoing abnormal growth are not with high SE and the nucleus of ALGs originate from static recrystallization triggered by SE. Differences in grain orientation spread (GOS) between grains serve as the driving force for AGG. The abnormal enlargement of grains coincides with the expansion of twin boundaries (TB). Σ3n (n = 1, 2 and 3) boundaries play an indispensable role in the formation and growth of ALGs.

Polyvinyl chloride (PVC)/polyethylene oxide (PEO)/x wt % polyaniline (PANI) polymer blends were produced using a solvent casting method. X-ray diffraction was used to investigate the formed blends. The effect of adding different amounts of PANI on the light absorbance, transmittance, reflectance, extinction coefficient, refractive index, optical dielectric properties, nonlinear optical parameters and relaxation time characteristics of the PVC/PEO blends were explored. The direct and indirect optical band gap energies of the undoped PVC/PEO were 4.25 and (4.06, 2.76) eV, respectively. The direct and indirect optical band gap energies were reduced to their lowest values (4.02, 3.1) and (3.68, 2.14, 1.12) eV as the amounts of PANI were increased to 0.2 wt %. The effect of alloying between PVC and PEO and adding PANI on the emitted fluorescence spectra under various excitation wavelengths were investigated. All samples displayed varying degrees of blue-violet, blue, or blue-green colors depending on the concentrations of PANI. [ABSTRACT FROM AUTHOR]

As an important green energy in our life, natural wind energy is widely used in power generation. Triboelectric nanogenerator (TENG) can convert wind energy in the environment into electrical signal. In this study, two independent TENGs in parallel (FHS-TENG) and the power management circuit composed of passive self-switching circuit and LC filter circuit constitute a self-supplying system, which is committed to harvesting wind energy in the environment and outputting stable voltage and improving energy storage performance. The self-switching circuit mainly includes rectifier module, energy storage module, the self-switching module, and filter module. And the on/off state of the passive self-switching is mainly controlled by two transistors, which implements the effect of switch. The results demonstrate that the energy stored by the power management circuit is more than 100 times higher than that of the universal circuit at 100 μF capacitor, and the calculator is in stable working order in simulated wind conditions. This work provides a new strategy for the passive electronic switch of TENG and the improvement of circuit energy storage performance, which is meaningful for the further application and industrialization of TENG. [ABSTRACT FROM AUTHOR]

The definitions of stored gravitational energy are given. The value of the limited gravitational energy of two massive mutually nonpenetrating balls is calculated. It is established that the stored gravitational energy is always positive. A formula is presented for the maximum possible gravitational energy of two massive balls, which can be used to estimate the energy of the merger of space objects, in particular, gaseous, dusty, and plasma, as well as for ballistic calculations of space flights. [ABSTRACT FROM AUTHOR]

Compacted graphite iron (CGI) is considered to be an ideal diesel engine material with excellent physical and mechanical properties, which meet the requirements of energy conservation and emission reduction. However, knowledge of the microstructure evolution of CGI and its impact on flow stress remains limited. In this study, a new modeling approach for the stress–strain relationship is proposed by considering the strain hardening effect and stored energy caused by the microstructure evolution of CGI. The effects of strain, strain rate, and deformation temperature on the microstructure of CGI during compression deformation are examined, including the evolution of graphite morphology and the microstructure of the pearlite matrix. The roundness and fractal dimension of graphite particles under different deformation conditions are measured. Combined with finite element simulation models, the influence of graphite particles on the flow stress of CGI is determined. The distributions of grain boundary and geometrically necessary dislocations (GNDs) density in the pearlite matrix of CGI under different strains, strain rates, and deformation temperatures are analyzed by electron backscatter diffraction technology, and the stored energy under each deformation condition is calculated. Results show that the proportion and amount of low-angle grain boundaries and the average GNDs density increase with the increase of strain and strain rate and decreased first and then increased with an increase in deformation temperature. The increase in strain and strain rate and the decrease in deformation temperature contribute to the accumulation of stored energy, which show similar variation trends to those of GNDs density. The parameters in the stress–strain relationship model are solved according to the stored energy under different deformation conditions. The consistency between the predicted results from the proposed stress–strain relationship and the experimental results shows that the evolution of stored energy can accurately predict the stress–strain relationship of CGI. [ABSTRACT FROM AUTHOR]

The microstructure of 6xxx aluminum alloys deeply affects mechanical, crash, corrosion and aesthetic properties of extruded profiles. Companies, especially in the transportation sector, require control over the grain structure in order to ensure the quality and the performance of the products. A main challenge for the extrusion companies is to accurately predict the profile microstructure at the design stage, trying to limit the formation of coarse grains and, consequently, the reduction of the mechanical properties of the component. In this work, the modeling of the stored energy, driving force for the recrystallization, was carried out and implemented within the Qform Extrusion FEM code. A novel approach for the evaluation of fibrous and recrystallized microstructures in 6XXX aluminum alloy profiles was proposed and tested in a campaign of experiments involving the extrusion of AA6082 round bars under several die designs and processing conditions. The outcomes proved the good accuracy of the recrystallization predictions during the extrusion of AA6082 aluminum alloy. [ABSTRACT FROM AUTHOR]

This study examines the effects of different intermediate annealing times during multi-pass cold-torsion tests on the microstructure in alloys of aluminum, magnesium, silicon, and copper (Al–Mg–Si–Cu). The mean flow stress, when the intermediate annealing time is shorter, increases until sufficient internal strain accumulates and then decreases rapidly. In contrast, the mean flow stress decreases continuously when the IA time is longer. X-ray line profile analysis revealed a rapid decrease in mean flow stress because of the high stored internal energy represented by the dislocation density. In addition, a short annealing time allows the B component to form in the initial stage of multi-pass torsion, and a random texture distribution occurs as the multi-pass torsion stage progresses. In contrast, a long annealing time can dissipate the texture distribution in a low-pass stage (low strain) and decreases the overall deformation resistance, despite the much stronger texture intensity in a high-strain area. Finally, the B texture component is consumed by the A component in the initial stages of the multi-pass cold torsion test. This is attributed to the different orientation relationships of the shear plane in the A and B components, which caused deviations in dislocation density.

The recrystallization (RX) kinetics of commercially pure Al alloy is studied under the scope of annealing temperature, time, and degree of deformation. To examine the distribution of recrystallization, Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory is employed, where the path of microstructural transformation from the deformed state to the fully recovered one is studied as a function of the volume fraction of recrystallized grains ( X V ) and annealing time. The drop in hardness is recorded for the samples at various stages of annealing with a corresponding decrease in stored energy as the annealing time increases. The stored energy obtained from the hardness results and Orientation Imaging Microscopy (OIM)-based method is found to be in good agreement with each other, proving the efficiency of both techniques. To determine the volume fraction of the recrystallized microstructure, data obtained from Vickers hardness measurements are used. Various parameters associated with recrystallization statistics such as the critical radius of nuclei, the incubation period, and the mobility of High-Angle Grain Boundaries (HAGB) were derived from the experimental evidence. The experimental data also suggest a sharp drop in the velocity of HAGB as the RX transformation process approaches its completion, which is found to be a direct result of a drop in stored energy. A softening window between 42 s and 55 s is identified for our experimental data where the hardness, stored energy, and velocity of HAGB drops very sharply, and the maximum fraction of deformed grains is expected to be converted to the recrystallized ones. Along with experimental observations, an analytical model was developed, which helps to approximate the kinetics of RX and corresponding parameters for various annealing temperatures and strains while revealing the characteristic feature of Avrami exponent n. Both experimental evidence and model data reveal a very strong dependency of recrystallization behavior on the stored energy. [ABSTRACT FROM AUTHOR]

Copyright of Tikrit Journal of Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The energy utilization ratio (ER) quantifies the utilization of a Switched Reluctance Motor (SRM). Calculation of ER of an SRM can be different from other motors as it has highly non-linear operating characteristics and uses an asymmetric bridge converter. In this paper, the concept of ER for SRMs has been explained first and then a computation methodology is presented based on the co-energy and stored energy in the magnetic system. The magnetic stored and co-energy are evaluated in ANSYS Maxwell for the static characterization of the motor. These magnetic energy quantities are computed under the dynamic operation of the SRM drive from the area under the flux linkage-current curve to compute the energy utilization. An experimental correlation is performed for validating the proposed ER computation methodology in SRM drives. Finally, the components of the energy utilization ratio are applied to determine the control objectives of a switched reluctance motor drive to improve the electromagnetic performance. Utilizing the energy utilization ratio components in the optimization of the phase turn on and turn off angles of an SRM helps to achieve a single optimization objective to improve the average torque, energy utilization, and torque ripple performance, and they can be used in multi-objective optimization, as well.

Utilizing thermal storage integrated into a solar air heater SAH is a promising solution to enhance the thermal performance of solar air heaters. The present work experimentally investigated the thermal impact of an absorber-finned heat exchanger-thermal storage unit integrated inside a solar air heater. The experiments were conducted under the conditions of Tikrit-Iraq in December 2021 and January 2022. RT42 and RT50 were used as PCMs in two separate solar air heaters. Each PCM filled the thermal storage of SAH. A finned heat exchanger, in which air was forced through, was immersed in the thermal storage. Two arrangements were tested. In the first arrangement, the two SAHs were separated from each other. In the second arrangement, the two SAHs were connected in series, first the RT42 SAH and then the RT50 SAH. The results showed that the highest recorded temperature was for RT50, i.e., 59 °C, in the separation arrangement. Also, the solar air heater with RT50 in the series arrangement continued to heat the forced air until 5 AM the next day.

This work compares conventional unidirectional rolling (UDR) and cross rolling (CR) based on mechanical properties, microstructure, and stored energy. Pure copper is subjected to UDR and CR to true strains of 0.69, 1.39, 2.08, and 2.77, respectively. The UDR samples show high strength and hardness compared to the CR. Investigation of microstructures of formed samples using optical microscopy and EBSD revealed that the grains were elongated along with the rolling directional for UDR and fairly equiaxed grains with reduced anisotropy for CR. The stored energy calculated using calorimetry experiments was correlated with mechanical and microstructure evolution. [ABSTRACT FROM AUTHOR]

Multifunctional β-titanium alloy Gum Metal, characterized by a relatively low elastic modulus, superelastic-like behavior and high strength, was subjected to cyclic tensile loadings. The characteristics of macroscopic scale energy storage and dissipation in the consecutive loading–unloading cycles were studied. Various kinds of energy components related to the alloy deformation process were determined experimentally and analyzed using thermodynamic relations. The values of the entire work needed to deform the alloy W e x t , the work used for recoverable deformation W r e c consisting of the elastic deformation energy W e l   , the superelastic-like energy W p t   , and the energy of thermoelastic effect E t h   , were derived from the Gum Metal stress and temperature vs. strain curves. The irrecoverable mechanical energy W i r expended on plastic deformation, the dissipation energy Q , and finally the stored energy E s   were estimated. The stored energy represents a change in the internal energy of the deformed material and is an essential measure of cold-worked state. The E s value turned out to be not large for the Gum Metal, which confirms the alloy low hardening property. The energy components determined for each of the 24 loading cycles enabled us to analyze various stages of the Gum Metal deformation process, including necking and damage. [ABSTRACT FROM AUTHOR]

Introduction: The right ventricle (RV) mechanical property is an important determinant of its function. However, compared to its elasticity, RV viscoelasticity is much less studied, and it remains unclear how pulmonary hypertension (PH) alters RV viscoelasticity. Our goal was to characterize the changes in RV free wall (RVFW) anisotropic viscoelastic properties with PH development and at varied heart rates.Methods: PH was induced in rats by monocrotaline treatment, and the RV function was quantified by echocardiography. After euthanasia, equibiaxial stress relaxation tests were performed on RVFWs from healthy and PH rats at various strain-rates and strain levels, which recapitulate physiological deformations at varied heart rates (at rest and under acute stress) and diastole phases (at early and late filling), respectively.Results and Discussion: We observed that PH increased RVFW viscoelasticity in both longitudinal (outflow tract) and circumferential directions. The tissue anisotropy was pronounced for the diseased RVs, not healthy RVs. We also examined the relative change of viscosity to elasticity by the damping capacity (ratio of dissipated energy to total energy), and we found that PH decreased RVFW damping capacity in both directions. The RV viscoelasticity was also differently altered from resting to acute stress conditions between the groups—the damping capacity was decreased only in the circumferential direction for healthy RVs, but it was reduced in both directions for diseased RVs. Lastly, we found some correlations between the damping capacity and RV function indices and there was no correlation between elasticity or viscosity and RV function. Thus, the RV damping capacity may be a better indicator of RV function than elasticity or viscosity alone. These novel findings on RV dynamic mechanical properties offer deeper insights into the role of RV biomechanics in the adaptation of RV to chronic pressure overload and acute stress.

In the present work, the effect of pre-annealing on the recrystallized texture of hot-rolled Fe-1.6 wt% Si non-oriented electrical steel was investigated. Vickers hardness test, optical microscope, and electron backscatter diffraction were used to investigate the changes in the average hardness, microstructure, and texture caused by pre-annealing of hot-rolled strips. It was found that the texture successively changed from a near-random distribution to {116} < 151 > texture and near-{001} < 140 > texture depending on pre-annealing treatments. Also, there was almost no effect on the grain size, and the average grain size of the normalized bands was 125 μm. Besides, the texture and magnetic properties of the final products under different pre-annealing treatments were also detected. It was found that the sample obtain a strong Cube texture by pre-annealing. Meanwhile, the magnetic properties are also got an improvement by pre-annealing. In a word, this method may provide a possibility to obtain an ideal grain size and texture simultaneously. [ABSTRACT FROM AUTHOR]

In order to confirm the vibrate compaction energy, the indoor vibration compaction was conducted. Indoor vibration compactor was used to compact skeleton dense cement stabilized aggregate. The acceleration and displacement of the indenter and compaction pressure during the compaction process were measured. The bounce model and the hysteresis curve based on measurement parameters were used to calculate the compaction energy. Three vibration compaction energy were affirmed as: energy of the machinery itself ( E s e l f ), energy transmitted from machinery to compacted material ( E t ) and energy stored by compacted materials ( E s ). The energy E s e l f was about 40 J (joule). During each compaction process, energy E t was only 1–1.8 J. In a one-minute compaction process, 2500 J of energy would be transmitted, but only 38 J could be stored by the compacted material. [ABSTRACT FROM AUTHOR]

In numerous engineering applications, the occurrence of highly rapid loading conditions, coupled with significant temperature rise, is prevalent. Under these harsh conditions, shear localization is a prominent material failure mechanism, which may result in catastrophic failure. Generally, materials possessing higher strength, limited work hardening rate, and lower thermal conductivity are more prone to mechanical instability. However, in the current study, a cryo-rolled CoCrNi alloy, characterized by much higher strength and limited work hardening, shows remarkable room and high-temperature mechanical performance under impact loading except at one temperature domain∼600 °C where this material displays mechanical instability by exhibiting adiabetic shearband. To shed light and understand this abnormal mechanical response, an in-depth microstructural study revealed that the ASB formation is closely linked to the recrystallization behavior of this alloy that is invariantly related to the stored energy of cold work, test temperature, and strain rate. Uniquely, the amplified nano-twinning activity at high strain rate and critical temperature promoted the fragmentation of grains and facilitated recrystallization, respectively. Once the recrystallization is completed, the alloy regains work hardening ability even at very high test temperatures, reaching 900 °C due to the deformation of the newly recrystallized matrix. The present work is valuable in delineating the alloy's application domain for rigorous impact and crash-worthiness applications, as there exists a dearth of literature on this material for dynamic scenarios. • Cryo-rolling introduces extensive twinning in CoCrNi. • Dynamic hot compression from room temperature to 900 °C. • Formation of shear band at only one critical temperature ∼600 °C,neither below nor above this temperature. • Dynamic strain rate induced secondary and tertiary twins fragment the deformed matrix into nano-sized blocks. • Shear band formation and propagation linked to stored energy of cold work and ambient test conditions. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry coupled with simultaneous evolved gas analysis (DSC-EGA) on aged δ-Pu samples shows that most radiogenic helium remains trapped within the Pu matrix at temperatures very close to, or slightly above, the melting temperature. Our results indicate that helium release from 50-year-old δ-Pu occurs as a burst just below the melting temperature (>0.994 T m), with subsequent pressure oscillations as temperature increases. Subordinate quantities of H 2 were also released along with helium. The helium emission tails off and ceases above ∼720 – 750°C. In a δ-Pu alloy aged 6 years, the initial helium burst occurs slightly above melting (∼1.015 – 1.042 T m), with a discrete, larger helium spike occurring between 670 and 686°C. The proximity of helium release to the liquidus transition presented challenges in the deconvolution of overlapping process enthalpies, the liquidus endotherm, and the exotherm resulting from bubble collapse, annealing and gas expulsion. Helium's strong affinity for vacancy binding in a 2He-vac configuration is predicted by Density Functional Theory (DFT) modeling. The measured stored energy associated with the He release events in a 50-year-old δ alloy is on the order of ∼10–11 J/g, which is significantly higher than stored energies measured in the sub-solidus regimes (∼2 J/g) that are related to the solid-state annealing of processing- and radiation-induced defects. This implies that aged δ Pu alloys have a remarkable resilience to accommodate the lattice strain produced by the internal pressure of the helium bubbles and provides further insight into the thermodynamic behavior of aged δ Pu. [Display omitted] • DSC-EGA analyses of aged δ-Pu samples document the emanation of a He + H 2 gas burst, while the metal is in the ε-phase. • During the 1st melt, an exothermic energy spike occurs immediately after the onset of normal endothermic melting. • Energy release during 1st melt is ∼10 J/g, corresponding to annealing of gas-filled voids formed due to self-irradiation. • Helium's affinity for vacancy binding, illustrated using DFT modeling, accounts for its abundance in the gas burst. • Aged δ−Pu alloys can accommodate lattice strain produced by gigapascal-scale internal pressures of He bubbles. [ABSTRACT FROM AUTHOR]

In the present investigation, equiatomic CoCrFeMnNi high entropy alloy (HEA) was subjected to 80% cold rolling (as-rolled) followed by isothermal annealing treatment at 700 °C for different time periods. Microstructural characterization was performed using electron back-scattered diffraction (EBSD) and electron channeling contrast imaging (ECCI) techniques on the as-rolled and annealed samples. The as-rolled microstructure consisted of elongated grains mainly composed of strong α-fiber and weak γ-fiber textures. The as-rolled sample showed the formation of ingrain SBs in the γ-fiber grains, which served as preferential sites for grain nucleation. The annealing treatment of as-rolled samples at 700 °C cause static recovery (SRV) before 5 minutes of heat-treatment, whereas static recrystallization (SRX) was observed after 5 minutes of heat-treatment in the CoCrFeMnNi alloy samples. A faster rate of recrystallization kinetics was observed after 15 minutes of heat-treatment. The annealing treatment reduced the intensity of α-fiber and enhanced the Copper, Cube and P ({011}<122>) texture components. Copper components originated from coarse recrystallized grains, which were the results of localized grain growth phenomena. Unusual behavior of banded featured α-fiber grains was observed during the annealing process. These banded grains in the partially annealed samples consisted of subgrain-boundaries and showed a delayed response to recrystallization as compared to grains with other orientations. Stored energy (SE) and Taylor factor (M) calculations were also used to understand the delayed recrystallization response of the banded featured/retained deformed grains. The microhardness value of the as-rolled sample was approximately 450 Hv, which decreased to around 230 Hv for the fully recrystallized grains. • Microstructural and texture evolution of the RTR+annealed CoCrFeMnNi HEA alloy were investigated. • Brass-oriented grains were showing the delayed in recrystallization. • Localized grain growth was observed for the Copper-oriented grains. • Copper-type shear bands were observed in the RTR CoCrFeMnNi sample. • The annealing treatment enhanced the Copper, Cube and P ({011}<122>) components. [ABSTRACT FROM AUTHOR]

Inhomogeneous deformation occurs in aluminum matrix composite, resulting in strain concentration near reinforcement/matrix interfaces. In this work, for the CNT/2024Al composite extruded by porthole die extrusion, the effects of reinforcements (CNTs and Al 4 C 3) and intermetallic (Al 2 Cu) on atomic strain concentration and grain boundary migration were systematically studied. The results indicate that obvious atomic strain concentration appears near the CNT/Al and Al 4 C 3 /Al interfaces, and then, the strain is transferred from the interfaces to Al matrix. Mirco-Al 2 Cu phases are mainly distributed at grain boundaries, increasing Zener force, and thus inhibit grain growth of the composite. In addition, the Al 4 C 3 /Al and Al 2 Cu/Al interfaces are observed, and the (111) Al atom plane is parallel to 1 ̄ 107 Al4C3 , while large number of misfit dislocations are observed near the Al 2 Cu/Al interface. Transmission Kikuchi diffraction and transmission electron microscope observations indicate that the grains, which contains more second phases, exhibit higher dislocation density than neighboring grains, providing driving force for grain boundary migration. High extrusion temperature brings about Al 2 Cu dissolution, leading to grain growth, and interfacial bonding strength decreases with increasing extrusion speed. Consequently, the composite extruded at low-temperature and low-ram speed has ultrafine grains, high dislocation density, and strong interfacial bonding, exhibiting high hardness, tensile strength and elongation. • Atomic strain concentration is illustrated by geometric phase analysis and molecular simulation. • The unevenly distributed dislocations in neighboring grains provide driving force for grain boundary migration. • Mirco-Al 2 Cu phases are dissolved at high temperature, leading to grain growth. • The composites extruded at low temperature and speed exhibits superior properties. [ABSTRACT FROM AUTHOR]

The recrystallization (RX) kinetics of commercially pure Al alloy is studied under the scope of annealing temperature, time, and degree of deformation. To examine the distribution of recrystallization, Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory is employed, where the path of microstructural transformation from the deformed state to the fully recovered one is studied as a function of the volume fraction of recrystallized grains (XV) and annealing time. The drop in hardness is recorded for the samples at various stages of annealing with a corresponding decrease in stored energy as the annealing time increases. The stored energy obtained from the hardness results and Orientation Imaging Microscopy (OIM)-based method is found to be in good agreement with each other, proving the efficiency of both techniques. To determine the volume fraction of the recrystallized microstructure, data obtained from Vickers hardness measurements are used. Various parameters associated with recrystallization statistics such as the critical radius of nuclei, the incubation period, and the mobility of High-Angle Grain Boundaries (HAGB) were derived from the experimental evidence. The experimental data also suggest a sharp drop in the velocity of HAGB as the RX transformation process approaches its completion, which is found to be a direct result of a drop in stored energy. A softening window between 42 s and 55 s is identified for our experimental data where the hardness, stored energy, and velocity of HAGB drops very sharply, and the maximum fraction of deformed grains is expected to be converted to the recrystallized ones. Along with experimental observations, an analytical model was developed, which helps to approximate the kinetics of RX and corresponding parameters for various annealing temperatures and strains while revealing the characteristic feature of Avrami exponent n. Both experimental evidence and model data reveal a very strong dependency of recrystallization behavior on the stored energy.

Two mesomechanics models were analyzed in an attempt to reveal the relationship between stored energy and back stress. It has been indicated that the portion of elastic stored energy due to residual microstresses (ESR) is closely related to intergranular back stress (Xinter), and the stored energy of dislocations inside grains (ESD) can be estimated with the plastic work of intragranular back stress (Xintra). Then, the evolution of back stress during cyclic loading was studied, and the plastic work of back stress (WpB) was calculated with the low cycle fatigue experimental data of Ti-6Al-4V. The result shows that WpB is partially released at every reverse loading, sufficient to reproduce the evolution of stored energy correctly under cyclic loading. The study also reveals that partially released energy is related to the decrease of Xinter at the initial state of reversal loading resulting from the reduction of the plastic strain incompatibility between grains. [ABSTRACT FROM AUTHOR]

In a grid-tied type-4 wind turbine generator (WTG) system, the frequency of sub/super-synchronous oscillation varies in a wide range, making it difficult to suppress the oscillation. In view of this problem, an active damping control strategy based on energy feedback is proposed. First, the energy balance equation of stored energy, dissipation energy, and interaction energy in a grid-tied type-4 WTG system is established. And the mathematical relationship between the increasing/decreasing trend of stored energy and the divergence/convergence of oscillation, no matter how the oscillation frequency varies, is derived. Then, by calculating the contribution degrees of different energy feedback branches to the variation rate of stored energy, the key energy feedback branches that cause the stored energy to increase are selected. And then, with the variation rate of stored energy being made negative as the control objective, this article derives a reactive current compensation function and constructs an additional energy feedback branch to eliminate the effect of key energy feedback branches, thus realizing active damping suppression of oscillations in a broad frequency band. Finally, the real-time digital simulator based hardware-in-loop test platform with a practical controller of a real 2.5-MW type-4 WTG and experimental platform are both built on which the proposed strategy is verified. Simulation results show that the proposed method can realize effective damping control of oscillations in a broad frequency range. In addition, this article is accompanied by a video demonstrating hardware-in-loop test results. [ABSTRACT FROM AUTHOR]

This current research work was aimed to develop an innovative panel by combining the nail-laminated timber (NLT) and cross-laminated timber (CLT) into a single product named nail-cross-laminated timber (NCLT) to take advantage of both structural panel products in a single product as a structural member. To investigate the mechanical properties of the NCLT, its bending performance and rolling shear were examined and compared to those of conventional CLT and NLT floor panels. The NCLT and the CLT panels were fabricated in 3 layers such as the CLT. Polyurethane adhesive was used on the laminations. The cross layers of the NCLT were made of a 30-mm-thick vertically laminated NLT. The NLT floor panels were fabricated by vertically nailing the laminations using a zigzag nailing pattern. Results showed no significant differences in the bending strength properties of the three panel types. Both CLT and NCLT showed a comparable rolling shear strength, however, the rolling shear failure in the NCLT was much more ductile than that of the CLT. Overall, the NCLT panels indicated an appropriate short-term bending and rolling shear performances. [ABSTRACT FROM AUTHOR]

Environmental factors affect the biological functions of aquaculture species both in the wild and in captivity. Therefore, optimization of the husbandry conditions under captivity can improve the production performance of an aquaculture species. In this study, the effect of water velocity on the glucose concentration, energy level of different body parts (i.e., hepatopancreas, gonad, muscle, and feces), and gonadal maturation of the Mud crab Scylla olivacea was evaluated. Immature crab samples of both sexes were collected from the Setiu Wetland and reared for 60 days in different water velocities (0, 20, 40, and 60 cm/s). The results of this study suggested that rearing the mud crab in 20 cm/s and 0 cm/s elicited the least stress as revealed by the glucose concentration of male and female crabs respectively when compared to other flow velocities. The trend of energy reserved in the hepatopancreas, and feces of both sexes however showed a significant decrease with the increasing flow velocity. A similar trend was also observed in the muscles of male S. olivacea. The energy in the muscle and gonad of the female mud crab on the other hand was higher in 20 cm/s and declining thereafter (with least recorded in 0 cm/s). This study also noticed that the 20 cm/s flow velocity advanced the stages of gonadal development (i.e., stages 3 and 4 for males and females respectively) of the crabs better than other flow velocities. It was therefore concluded that the 20 cm/s flow velocity is optimum to induce gonadal maturation and lessen the stress encountered by S. olivacea in captivity.

The selective 3D growth of multiple recrystallization nuclei/grains around a hardness indentation into a deformed Al grain has been quantified through a new approach that combines two synchrotron techniques: 3D X-ray Laue micro-diffraction and diffraction contrast tomography. The former is used to characterize the deformed microstructure and nucleation, while the latter to track the nuclei's growth during interrupted in situ annealing. The combined 4D (x,y,z,t) datasets enable a detailed quantification of the local deformed microstructure consumed by the nuclei/grains and the boundary characteristics between them, including the stored energy and anisotropy of the orientation distribution of the deformation matrix, as well as the misorientation of the moving and non-moving boundary segments. It is found that only certain nuclei can grow into large sizes, and the growth is heterogeneous both among recrystallizing grains and along different directions. Neither the local stored energy nor the boundary misorientation, whether considered individually or in combination, can fully account for the observed growing and shrinking behavior. The growth difference along different directions is related to the deformation microstructure, specifically the geometrical alignment of dislocation boundaries. Furthermore, the effects of impingement of other recrystallizing grains, recovery of the matrix, and elastic strain/stress, on the growth heterogeneities are discussed in detail with a view towards developing advanced modeling with improved predictability of local recrystallization phenomena. The present study demonstrates the effectiveness of the new approach in enabling 3D analysis of recrystallization in complex materials, with potential applications in the development of advanced engineering materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The relevance of the research.One of the leaders in production of aluminum powders in Russia OOO «SUAL-PM» has passed from production of coarse powders to production of micron powders with higher reactivity. Aluminiummicropowders are used in many branches of industry: powder metallurgy, self-propagating high-temperature synthesis of new materials, hydrogen energy, pyrotechnics and rocket fuels. Increase of aluminium powders reactivity in various processes leads to reduction in energy consumption and resource saving. The main aim of the researchwas to obtain and explain experimental data on changes in activity parameters of aluminiummicropowders after radiation exposure, depending on the γ-radiation dose. Objects: micron-scaled aluminium powdersASD-6,ASD-6М. Methods: differential thermal analysis, X-raydiffractionanalysis, method of aluminiummicropowdersexposurewithγ-radiation, method of calculation ofthe activity parameters of aluminium powders. Results. Quantitative indicators of the reactivity of aluminiummicropowders ASD-6 and ASD-6M before and after exposure with γ-radiation were obtained. The radiation source was the Co60 isotope with the energy of 1,17 and 1,33 MeV, i.e. the energy substantially below the threshold of photonuclear reactions. The doses to the powder samples exposure were 1, 2, 4, 8, and 10 Mrad. After γ-radiation exposure the micropowders oxidation start temperature has maximally decreased on 90 and 85 °C; maximal oxidation rate increased by 83 and 36 %; the degree of oxidation (at heating up to 1250 °C) increased by 5,1 %, and minimally decreased by 1,3 % for the ASD-6 and the ASD-6M micropowders, accordingly. The specific thermal effect of oxidation after γ-radiation exposure with all doses was greater than for non-exposed powders; the maximum values of the specific thermal effect was on 199,5 kJ/mol for ASD-6, and 134,8 kJ/mol for ASD-6M higher than thermal effects for non-exposed powders, which significantly exceeds the standard heat of aluminium melting (10,8 kJ/mol). Consequently, such a state of the «aluminium – aluminium oxide» system is characterized by the stored energy, 9 times higher than the standard heat of aluminium melting, which is impossible according to thermodynamics. At the same time, it is known that energy is stored in nanopowders due to the formation of a double electric layer in aluminium particles.

New rolling technique, i.e. asymmetric rolling combined with cross rolling is adopted to produce Ta sputtering targets in this study. Electron backscatter diffraction (EBSD) analysis suggests that {111} and {100} deformed grains distribute alternately along normal direction in cross rolling (CR) and asymmetric cross rolling (ACR) samples. Misorientation angle distribution indicates that severe orientation-dependent grain fragmentation exists in the CR sample, which is also confirmed by kernel average misorientation and grain reference orientation deviation-hyper. Grain average misorientation (GAM) and distribution of geometrically necessary dislocations (GNDs) suggest that the effect of increasing shear strain introduced by asymmetric rolling on deformation microstructure is mainly reflected in the {100} grains, which is further verified by orientation-dependent microhardness values. The computation of Schmid factor indicates that slip within {100} grains in the ACR sample is easier, and the system with higher Schmid factor can alone accommodate the majority of plastic strain. Transmission electron microscopy (TEM) reveals that dense dislocation walls (DDWs) are formed within the {100} deformed grains in the ACR sample, while only sparse dislocation lines can be observed in the CR sample. X-ray line profile analysis (XLPA) displays that ACR can significantly increase the stored energy of the {100} deformed grains and thus weaken the orientation-dependent stored energy distribution. The enhanced recrystallization ability of the {100} grains in the ACR sample facilitates homogenization of the annealing microstructure.

Prosthetic upgrades are specialized prosthetics that enable patients to participate in more demanding recreational activities, such as running. This study examines the use of prosthetic limbs, specifically the athletic prosthetic foot. The current research focused on the manufacturing and production properties of an samples athletic prosthetic Foot made from composite materials based on a polymethyl methacrylate resin (PMMA) reinforced with various fibers (UHMWPE, Perlon, Carbon fiber, and Glass fiber). The finite element method (ANSYS-19R) is used to build an athletic prosthetic model and apply boundary conditions to investigate the influence of deformation and stored energy on the performance of the sports prosthetic foot. Six laminates have been manufactured, and it has been discovered that adding a number of carbon fiber layers to UHMWPE has a better effect on deformation than adding a glass fiber 26% improvement. Furthermore, the findings show there is an improvement in performance when the number of classes was doubled, as the rate of improvement between the laminate to which carbon fibers were added was 31%, and between the laminate to which glass fibers were added by 32% under the same boundary conditions. [ABSTRACT FROM AUTHOR]

Summary: To reduce the investment cost of voltage sag mitigation equipment and the probability of voltage sag at the installation nodes of sensitive load, a comprehensive voltage sag mitigation strategy based on sensitive load clustering is proposed. The Monte Carlo method is used to get the stochastic estimation model of voltage sag to determine the lines with high fault probability, so as to get the weak links in the power grid, that is, the voltage sag vulnerable area. This paper proposes four sensitive indicators called tolerance magnitude of voltage sag, endurance duration of voltage sag, equipment capacity, and power dependence. The weight of each indicator is determined by the combination weighting method, and the affinity propagation (AP) clustering algorithm is used to classify different sensitive loads. The sensitive loads are mitigated by installing the energy storage equipment and dynamic voltage restorer (DVR), and the energy storage capacity is configured with the goal of minimum life cycle cost under the premise of voltage compensation. The result using MATLAB/Simulink and the laboratory equipment shows that, compared with existing mitigation strategies, the proposed mitigation strategy can not only effectively reduce the investment cost and the probability of voltage sag but also make the voltage distribution more reasonable. [ABSTRACT FROM AUTHOR]

Two mesomechanics models were analyzed in an attempt to reveal the relationship between stored energy and back stress. It has been indicated that the portion of elastic stored energy due to residual microstresses (ESR) is closely related to intergranular back stress (Xinter), and the stored energy of dislocations inside grains (ESD) can be estimated with the plastic work of intragranular back stress (Xintra). Then, the evolution of back stress during cyclic loading was studied, and the plastic work of back stress (WpB) was calculated with the low cycle fatigue experimental data of Ti-6Al-4V. The result shows that WpB is partially released at every reverse loading, sufficient to reproduce the evolution of stored energy correctly under cyclic loading. The study also reveals that partially released energy is related to the decrease of Xinter at the initial state of reversal loading resulting from the reduction of the plastic strain incompatibility between grains.

This paper aims to show the effects of primary stored energy in high entropy bulk metallic glasses (HE-BMGs) on their relaxation behavior after elastostatic loading process. For this purpose, three HE-BMGs with different chemical compositions and primary stored energy were fabricated. Differential scanning calorimetry and nanoindentation tests were carried out to evaluate the relaxation enthalpy and microscopic mechanical characterization of alloys. The results showed that increase in the number of element types in the alloying composition leads to the increment of stored energy and structural heterogeneity in the primary alloys. Moreover, the elastostatic loading rejuvenates the primary alloys; however, an optimum heterogeneity is needed for the maximum structural heterogeneity and stored energy in the glassy alloy. The hardness measurements also indicate that the elastostatic loading intensifies the hardness variations in the alloys, which may be due to the increased structural heterogeneity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stored energy evolution tends to some asymptotic value close to damage. • Analysis of the AE signal revealed two different clusters during crack propagation. • Heat dissipation correlates with AE signal cluster probably associated with crack growth. • The stored energy is sensitive to AE signal cluster probably associated with twin density. The aim of this work was to investigate the correlation between structural, acoustic emission and thermal characteristics of the fatigue crack growth in titanium alloys. Cluster analysis of the acoustic emission signals revealed two different types of signals recorded during the development of a fatigue crack. It has been shown experimentally that the evolution of the stored energy tends to an asymptotic value at the final stage of fatigue crack growth and it correlates with the intensification of the twinning process in titanium alloy Ti Grade 2. A correlation was assumed between the stages of change in the heat flux, the cumulative energy of the first cluster of AE signals and the crack length. [ABSTRACT FROM AUTHOR]

Introduction Greenhouse cultivation has been increased in response to population growth, reduction in available supplies and arable lands and raising the standards of living. The quality and quantity of the products are profoundly affected by the greenhouse temperature. Therefore, providing an appropriate heating system is an elementary requirement for greenhouse cultivation. A number of factors such as glazing material, greenhouse configuration, product type, and climate conditions should be considered to design a greenhouse heating system. Due to the environmental concerns associated with the fossil fuels, renewable energy-powered heating systems such as geothermal, solar and biomass- are increasingly considered as the alternative or supplementary to the traditional fossil fuel heating equipment in greenhouses. In this way, a number of researchers have developed different greenhouse heating systems to reduce fossil fuel consumption. In Iran, because of appropriate available solar irradiance, the solar heating systems can be efficiently employed for greenhouse cultivation. A compound solar greenhouse heating system was experimentally and analytically investigated in the present study. To verify the obtained heat transfer equations, a set of experiments were carried out at Biosystems Engineering Campus of the Shahid Bahonar University of Kerman. Material and Methods The designed system was comprised of a Parabolic Trough solar Collector (PTC), a dual-purpose modified Flat Plate solar Collector (FPC) and a heat storage tank. The modified FPC was located inside the greenhouse to act as a heat exchanger to transfer the stored heat to the greenhouse atmosphere during the night. The FPC also collects the solar radiations during the sunshine hours to enhance the thermal energy generation. Heat transfer equations of the PTC and the FPC were written and the useful energy gain of the heating system was determined at the quasi-static condition during the day. Experimental verification of the analytical models was conducted using regression coefficient (r) and root mean square percent deviation (e) criteria as follows: where Xi and Yi are respectively the ith analytical and experimental data and n shows the number of observations. Exergy analysis of the PTC and the FPC were carried out and the effect of the different fluid flow rates through the PTC on the exergy efficiency of the different components was investigated using the experimental data. Results and Discussion Increasing the fluid flow rate increased outlet temperature of the PTC due to the increase in heat removal factor and inlet temperature; whereas, caused a reduction in outlet temperature of the FPC. Since the thermal efficiency of the PTC improved with the fluid flow rate, the PTC fraction enhanced when the flow rate increased from 0.5 to 1.5 kg min-1. However, the PTC fraction values were less than 50% and sometimes have dropped below zero. The exergy efficiency of the PTC improved with increasing the flow rate. The reason was that the difference between the inlet and outlet temperatures of the PTC increased with the flow rate at the similar conditions of solar irradiance and ambient temperature. The highest exergy efficiency of the FPC was observed at the flow rate of 0.5 kg min-1. Conclusions The results of the study revealed that: There was a suitable agreement between the obtained analytical expressions and the experimental data based on root mean square percent deviation and regression coefficient criteria. The highest stored energy in the tank was around 40.02 MJ at the flow rate of 0.5 kg min-1. Increasing the flow rate improved the PTC exergy efficiency.

The relevance. Aluminum micropowders are the precursors in many industries, such as powder metallurgy, self-propagating high-temperature synthesis of new materials, hydrogen energy, pyrotechnics and rocket fuels. Improvement of characteristics of aluminum powders contributes to their quality. The known methods of aluminum powders activation by addition of rare-earth elements, vanadium compounds, silicon, boron and other elements into the aluminum mixtures composition lead to contamination of aluminum with impurities. β-radiation exposure of micropowders with the energy less than 8 MeV does not lead to induced radioactivity and activates aluminum micropowders at the same time. The main aim of the paper was reception and explanation of experimental results on the activity parameters of aluminum micro-powders after exposure, depending on the β-radiation dose. Objects: micron-scaled aluminium powders ASD-6, ASD-6М, ASD-8, ASD-10 obtained by aluminium fusion sputtering. Methods: differential thermal analysis, X-ray diffraction analysis, the method of aluminum micropowders exposure with β-radiation, the method of calculation of the activity parameters of aluminum powders. Results. The quantitative indicators of the ASD-6, ASD-6М, ASD-8, ASD-10 aluminum micro-powders reactivity before and after exposure in the ELU-4 accelerator by 4-MeV β-radiation (i. e. the energy is significantly lower than the threshold of photonuclear reactions) were obtained in the work. The doses of powder samples exposure were 1, 2, 4 Mrad. After β-radiation exposure the oxidation start temperature decreased maximally to 205 °C; maximum oxidation rate increased by 0,19 mg/min (106 m%); the oxidation degree of the ASD-6M micropowder increased by 18,9 %, and of the ASD-10 minimally decreased by 12,3 %; the specific thermal effect of oxidation after all doses of β-radiation increased maximally for ASD-10 by 188,6 kJ/mol. Energy storage by micropowders after β-radiation is caused by the formation of a double electric layer in aluminum particles.

Energy dissipation in metals under irreversible deformation leads to intensive heat generation in strain localization zones. In this work, we focus on measuring heat source power using temperature data obtained by IR thermography. The calculated heat source power data were verified by analyzing the data recorded by the Seebeck effect-based heat flux sensor developed in previous study. Quasi-static tensile tests were conducted on titanium alloy Grade 2 flat specimens. It is shown that the thermography data and the results obtained with the heat flux sensor are in good quantitative agreement. The dependence of the moment of fracture of metal specimens on the change in localized heat generation caused by irreversible deformation was determined.

(Na 0.5 Bi 0.5) 0.4 Sr 0.6 Ti 1- x Zr x O 3 relaxor ferroelectric ceramic were prepared by a traditional ceramic preparation process introducing Zr4+ at the B-site. It was observed that introducing an appropriate amount of Zr4+ ions into the NBST matrix can improve the energy storage efficiency. (Na 0.5 Bi 0.5) 0.4 Sr 0.6 Ti 0.5 Zr 0.5 O 3 shows excellent energy storage density up to 2.83 J/cm3, and excellent efficiency (83.90 %) at 220 kV/cm. A single layer ceramic capacitor (SLCC) was also prepared by the tape casting technique for multilayer ceramic capacitors (MLCCs) to further enhance the energy storage performance. The recoverable energy storage capacity is increased to 4.52 J/cm3 and the efficiency is 70.02 % at 460 kV/cm. Moreover, it still has a relatively stable energy storage performance after 105 cycles of charge and discharge. This sample has exhibited outstanding energy storage performance, fatigue resistance, and charge/discharge performance and has great potential value in practical applications. [ABSTRACT FROM AUTHOR]

Steam injection and thermal recovery of oil from the reservoir are increasing day by day. However, the recovery of the heat remained stored in the steam-flooded oil reservoir is nor in practice neither researched previously. A novel concept of steam injection and energy recovery from a light oil reservoir is presented in this paper. Reservoir numerical model of an actual oil field was generated and simulated with steam injection. Different parameters of thermal properties of geologic formations were discussed and adopted as per actual geology of the study area for more realistic simulation of heat storage, dissipation, and losses. After the optimum oil recovery, water was circulated through the same injection well into the reservoir to extract the energy in the form of heat, stored during the steam injection phase. The effects of different completion schemes of injection well were also simulated, discussed and pointed out for optimum oil recovery. Oil recovery factor is the most important parameter from both research and field development point of views. The comparative analysis was also carried out with the oil production without steam injection and found that steam flooding increased oil recovery factor up to more than 15% by decreasing the production time period up to 40% as compared to without steam injection oil production. The transmission of heat through conduction and convection mechanisms in the porous media, and through advective, dispersive and diffusive processes in the fluid was modeled. To fully investigate the feasibility of the concept presented in this paper, the production wellbore modeling was also carried out and temperature profile of recovered heat energy at the wellhead was obtained by acknowledging the thermal losses and found to be very useful for any direct and indirect utilization of heat throughout the energy recovery period of the reservoir. [ABSTRACT FROM AUTHOR]