Search Results (568)

Solid oxide electrolysis cells (SOECs) are promising devices for high-efficiency hydrogen production using variable renewable energy. However, dynamic operation involves complex interactions among electrochemical heat generation or absorption, gas heat transfer, temperature-dependent cell voltage, and thermal inertia of stack components. Therefore, mechanical reliability should be evaluated together with load-following performance. In this study, a transient stress analysis framework was developed for an SOEC stack by coupling a transient temperature distribution model, finite element stress analysis, and a surrogate model. The temperature model considers the active cell region, inactive cell region, and edge region, and calculates the evolution of in-plane temperature distributions during power fluctuations. The obtained temperature fields were transferred to finite element stress analysis to evaluate the stress states of the YSZ electrolyte, Ni-YSZ hydrogen-electrode support, and metal interconnector. To enable long-duration evaluation, a surrogate model was constructed from finite element results and applied to time-series temperature distributions under dynamic operating conditions. The suggested framework enables efficient estimation of transient stress histories and clarifies how temperature gradients formed during load changes affect stack components. This approach provides a useful basis for assessing mechanical reliability and designing operating strategies for SOEC stacks coupled with variable renewable energy. Full article

Ultrawide bandgap (UWBG) semiconductors are destined to become the foundation for next-generation power and radio-frequency (RF) electronic devices. Their superior qualities such as high thermal conductivity, strong critical electric field, and robust mechanical and radiation hardness are driving continuous and widespread research. Amongst the UWBG materials, aluminum nitride (AlN) is highly attractive due to its direct ultrawide bandgap of about 6.2 eV, resulting in one of the highest Baliga’s and Johnson’s figures of merit. Equally important as its properties are material availability and growth methods capable of producing large-diameter substrates. In this work we report on bulk growth of 100 mm AlN crystals using the physical vapor transport (PVT) technique. The thermal gradients were simulated and tailored to obtain adequate thermal stresses, resulting in substrates with narrow X-ray rocking curves and dislocation densities in the range of 10²–10⁵ cm⁻². In addition, the room-temperature thermal conductivity measured in two directions, perpendicular and parallel to the c-axis, was confirmed to be 300 W m⁻¹ K⁻¹. AlN substrates also demonstrated high UV transparency with absorption coefficients as low as 10 cm⁻¹ at 265 nm wavelength. These results, along with the availability of 100 mm substrates, demonstrate that AlN is ready for further exploration and development for the power and RF electronics industry. Full article

The front-end wide-temperature-range gas-mixing flow system of a high-altitude test chamber is a key component for simulating inlet conditions over a wide temperature range, and the temperature uniformity of the mixed gas as well as the positional stability of the downstream interface directly affect the accuracy of the test boundary conditions. To address the nonuniform temperature field, thermal deformation of the main pipeline, and local thermal stress concentration arising from the combined effects of large temperature differences, long-distance piping, and high-pressure operating conditions, this study establishes a multiphysics coupling analysis framework based on ANSYS Fluent 2021 R1, CAESAR II, and ANSYS Mechanical, and systematically investigates the temperature distribution in the mixing section, thermal boundary transfer, the global thermal response of the piping system, locally refined models, and the compensating effect of expansion joints. The fluid–thermal results show that the temperature distribution of the mixed gas in the right-side section of the pipeline varies among the representative operating conditions, under which the branch mass-flow allocation, total flow rate, inlet total pressure, and inlet total temperature change simultaneously. To enable quantitative comparison, a temperature nonuniformity coefficient γ (the standard deviation of cross-sectional temperature divided by mean temperature) is introduced. For each temperature combination, Cases 1 to 3 represent operating conditions dominated by the 40 °C branch, whereas Cases 4 and 5 represent conditions dominated by the −70 °C branch in the 40 °C/−70 °C group and by the 550 °C branch in the 40 °C/550 °C group. Under the selected 40 °C/−70 °C cases, the γ values at the downstream monitoring section decrease from 8.72% in Case 1 to 3.86% in Case 3, confirming progressively smoother temperature distributions, whereas γ increases from 6.31% in Case 4 to 9.87% in Case 5, indicating stronger thermal stratification. Under the selected 40 °C/550 °C cases, γ reaches its minimum of 2.87% in Case 2, while the comparison between Case 4 (γ = 9.54%) and Case 5 (γ = 5.78%) shows that the increase in flow-rate difference in the dominant branch is associated with improved temperature uniformity. Thermo-structural coupling analysis further indicates that the main pipeline is the key component governing the overall thermal deformation of the system, that axial thermal expansion dominates under high-temperature conditions, and that local high stresses are mainly concentrated at fixed supports and in adjacent regions with abrupt geometric constraint changes. Further analysis demonstrates that expansion joints modeled using equivalent stiffness can reduce the Z-direction displacement at key locations of the main pipeline by 10.94, 16.46, 9.58, and 10.50 mm under four typical operating conditions, respectively, while shifting the critical region from the main pipeline support area to the vicinity of the compensating components. These results can provide a reference for controlling interface thermal displacement, designing the main pipeline structure, and arranging expansion joints in front-end gas-mixing systems. Full article

This study aims to investigate the influence of non-local elasticity on the coupled optoelectronic photo-thermoelastic response of an anisotropic fiber-reinforced silicon half-space subjected to optical carrier excitation. A coupled analytical model is developed by incorporating non-local elasticity into a fiber-reinforced anisotropic semiconductor framework, where the thermal, carrier-density, displacement, and stress fields are fully coupled. After introducing the appropriate non-dimensional variables, the governing equations are transformed using the normal-mode technique into a system of ordinary differential equations and solved analytically through an eigenvalue-based vector–matrix approach. The novelty of the present work lies in examining the influence of the non-local parameter within a fiber-reinforced anisotropic semiconductor and performing a systematic comparison between fiber-reinforced and non-reinforced configurations under identical photothermal loading conditions. The numerical results demonstrate that increasing the non-local parameter produces pronounced changes in the mechanical response, including displacement amplitudes, stress distributions, and wave attenuation characteristics, whereas the temperature and carrier-density fields exhibit only slight variations within the investigated parameter range. Fiber reinforcement further influences the mechanical response by enhancing the structural stability and directional stiffness of the medium. The proposed analytical framework provides physical insight into the coupled effects of nonlocality and fiber reinforcement, with potential relevance to the analysis and design of semiconductor devices, optoelectronic and photonic structures, MEMS/NEMS, and smart fiber-reinforced composite materials operating under coupled thermo-mechanical and optical excitations. Full article

Rockbursts occur frequently in deep hard-rock tunnels, posing a major challenge to the safe and efficient construction of underground engineering. Engineering practice shows that in addition to high in-situ stress and hard brittle lithology, widely distributed structural planes in surrounding rock also significantly modify rockburst failure modes and intensity. This review systematically investigates structural-plane-controlled rockburst phenomena in deep hard-rock tunnels, based on 16 published field cases and more than 40 laboratory studies. First, we summarize the influence mechanisms of structural planes on tunnel rockbursts at the engineering scale through statistical analysis of case data. We then integrate existing experimental findings to analyze how the geometric and physical properties of structural planes alter rockburst behavior, from four perspectives: location (concealed/exposed), attitude (dip angle, strike, length), filling state, and multi-plane combination. We further synthesize multi-physical field response characteristics (acoustic emission, infrared thermal radiation, and surface strain field) from laboratory tests, and compare crack propagation and energy evolution patterns dominated by structural planes. The scale dependence of structural plane effects is discussed, highlighting consistencies and discrepancies between laboratory-scale mechanisms and field-scale engineering phenomena. Finally, we analyze rockburst mechanisms under the coupled action of structural planes and dynamic disturbances, and propose targeted engineering control strategies for different structural plane conditions. The purpose of this review is to integrate a set of analysis frameworks to establish the relationship between structural plane characteristics (location, attitude, filling state, and multi-plane combination) and multi-physical field responses, fracture evolution and energy evolution laws, as well as engineering-scale rockburst behavior. It is noteworthy that the engineering cases compiled in this review predominantly originate from deep hard-rock tunnels in China. The universality of the impact of structural planes on rockbursts still needs to be further verified by combining cases from different structural settings and engineering backgrounds. Full article

This study investigates the under-explored contribution of internal radial stress to macroscopic gravitational potentials. We utilize a novel, precision-damped torsion balance apparatus designed to isolate and measure gravitational perturbations induced by radial stress within rapidly rotating macroscopic masses, rigorously controlling for acoustic, thermal, and electromagnetic variables. Our findings document an anisotropic mechanical influence along the plane of rotation that exceeds standard weak-field gravitational predictions. The measured apparatus potential exhibits a kinematic scaling ($\propto {\omega }^4$) consistent with a linear torsion spring responding to an underlying quadratic (${\omega }^2$) driving force. While active Herzan leveling, counter-rotating geometry, and precision balancing successfully eliminated bulk frame-drag and mechanical vibration, this atmospheric baseline study concedes that the persistent ${\omega }^2$ force may still be masked by complex, non-linear fluid dynamic asymmetries. Consequently, this paper establishes a ‘Stage 1’ methodological baseline, mapping the absolute limits of atmospheric testing and defining the engineering prerequisites for future high-vacuum gravitational extractions. Isolating this residual force in a future high-vacuum environment is imperative. Should such testing confirm the signal is gravitationally sourced, this anisotropy suggests a potential coupling between the internal stress-energy tensor and the local spacetime metric that is not fully accounted for in standard linear approximations. If this phenomenological stress-metric coupling can be isolated and shown to scale macroscopically, it could theoretically provide a non-linear mechanism for observed rotational gravitational symmetry breaking. The speculative astrophysical implications of such a coupling are also discussed. Full article

Chilo sacchariphagus is a destructive sugarcane borer worldwide, and frequent extreme high temperatures disrupt its field populations. Clarifying larval thermal response mechanisms provides theoretical support for pest risk prediction under climate warming. Previous work has illustrated moderate heat induces canonical HSP activation, but the molecular responses of this pest to 41 °C extreme heat remain unclear. As such, we conducted non-reference transcriptome sequencing and 11 physio-biochemical assays on fifth-instar larvae exposed to 41 °C for 12 h (26 °C as control) to characterize its thermal regulatory network. De novo assembly yielded a comprehensive transcriptome resource, and analysis of differentially expressed genes revealed enrichment in energy metabolism, ER protein processing, MAPK signaling and autophagy pathways. Core HSP70/40 transcripts were significantly down-regulated while HSP80 showed stable transcription, suggesting that 41 °C may exceed the heat-shock protective threshold and potentially trigger heat damage. qRT-PCR validation of seven core stress genes confirmed the RNA-seq trends. Catalase (CAT) activity increased significantly; however, none of the annotated catalase genes showed transcriptional changes, whereas elevated CarE and AchE activities also lacked corresponding transcriptional shifts, implying post-translational or alternative regulatory mechanisms. Our data showed coordinated transcriptional and physiological changes under extreme heat. These findings provide a basis for further investigation into how C. sacchariphagus may respond to extreme heat under climate warming scenarios. Full article

To address the issues of low mechanical rock-breaking efficiency and severe tool wear in hard rock, this study investigates the mechanical deterioration and abrasivity response of granite subjected to rapid flame-jet heating followed by liquid nitrogen cooling, with rock pre-treatment in thermal-assisted rock breaking as the background. Fine-grained granite specimens were heated by flame jet to temperatures ranging between 200 and 600 °C and then subjected to natural cooling or sudden liquid nitrogen cooling. Physical parameter measurements, uniaxial compression tests, Brazilian splitting tests, and CERCHAR abrasivity tests were conducted using national standards to investigate the evolution of thermal damage and the effect of cooling path. The results show that the damage degree of granite continuously increases with increasing heating temperature, and the damage induced by liquid nitrogen cooling is greater than that induced by natural cooling. Visible cracks begin to appear on the specimen surface after 300 °C, while crack propagation and structural deterioration become more pronounced at 500–600 °C. Among the measured physical parameters, P-wave velocity is the most sensitive to damage, with a maximum attenuation rate of 60.6%. The deterioration of the physical structure further reduces the load-bearing capacity and deformation performance of granite. After liquid nitrogen cooling at 600 °C, the uniaxial compressive strength, tensile strength, and elastic modulus decrease to 92.6 MPa, 1.42 MPa, and 17.4 GPa, respectively, corresponding to reductions of 56.0%, 87.7%, and 69.3% compared with the untreated specimens. The tensile strength is the most sensitive mechanical parameter to liquid nitrogen cooling. The CERCHAR abrasivity index decreases from 3.81 to 2.12. Liquid nitrogen cooling advances the transition of granite abrasivity from high to medium from 400–500 °C to 300–400 °C. The integrated analysis indicates that the non-uniform temperature field generated by rapid flame-jet heating and the differences in thermal deformation among minerals promote the initiation of initial cracks. The additional shrinkage stress induced by liquid nitrogen cooling further drives crack propagation and coalescence, eventually leading to the coupled reduction in the strength, stiffness, and abrasivity of granite. The results provide laboratory-scale evidence for evaluating granite pre-treatment under rapid flame-jet heating and liquid nitrogen cooling and offer a reference for thermal-assisted mechanical rock breaking and standardized abrasivity reduction. However, the relationship between CAI and actual tool wear still requires further verification. Full article

Cellulose insulation paper used in oil-immersed power transformers is vulnerable to molecular chain loosening and aging-product transport under thermal and electrical stresses. Nanomodification is a promising route for improving insulation-paper stability, but the atomistic mechanisms by which KH550-grafted oxide nanoparticles regulate cellulose structure and aging-molecule mobility under an external electric field remain insufficiently clarified, particularly when the role of oilpaper insulation aging and oil-contact environments is considered. In this work, pristine cellulose and cellulose modified with KH550-grafted SiO₂ and Al₂O₃ nanoparticles were investigated using molecular dynamic simulations at 343 K under a uniform electric field of 0.01 V/Å (100 kV/mm) applied along the Z-axis. Based on the MSD and apparent transport-parameter results, nanomodification reduced the MSD-derived apparent coefficients of H₂O and CO₂ by 33.7–51.9%. The external field produced apparent directional transport bias, with Z/X apparent-coefficient ratios of 2.21 for H₂O and 2.02 for CO₂ in pristine cellulose. These ratios decreased to 1.62 and 1.51, respectively, in the KH550–Al₂O₃ model. Interfacial interaction energy analysis showed that the KH550–SiO₂ interface became more strongly bound under the field (−240.50 to −252.13 kcal/mol), whereas the KH550–Al₂O₃ interface remained nearly unchanged (−541.65 to −538.81 kcal/mol). Because the two nanomodified systems use different nanoparticle loadings and KH550 grafting ratios, cross-system differences are interpreted as model-specific outcomes rather than effects attributable only to nanoparticle chemistry. These results indicate that KH550-grafted nanoparticles may help maintain cellulose packing under the modeled conditions and suppress aging-molecule mobility in the simulated cellulose matrix, while the conclusions should be interpreted as atomistic simulation evidence rather than direct proof of long-term transformer reliability. Full article

This study takes the Ankang area in the Qinling–Dabashan Mountains on the northern margin of the Yangtze Block as an example to investigate whether effective shale gas preservation conditions can exist in large-scale thrust nappe belts at convergent plate margins—a critical scientific question. The aim is to provide new concepts and models for shale gas exploration in tectonically complex regions. An integrated approach combining surface geological mapping, geophysical surveying (2D seismic and wide-field electromagnetic method), calibration of a key borehole (ZBDR01), and geochemical analysis was employed to reconstruct the deep geological structure and evaluate the hydrocarbon generation potential and reservoir characteristics of the target shale interval. The results reveal a relatively gentle, weakly deformed “structural stability window” beneath the Zhongbao Fault, a major thrust nappe surface. Within this window, strata dip at low angles and faults are sparse, exhibiting a significant stress-shielding effect. The Lower Cambrian Niutitang Formation shale within this window is well preserved, characterized by high total organic carbon (average TOC: 4.26%) and moderate thermal maturity (average R_o = 3.02%), falling within the effective shale gas generation window. In contrast, the Lujiaping Formation shale in the hanging wall of the fault, though widely distributed, shows excessive thermal maturity and poor reservoir properties. The study demonstrates that the “stress-shielding” effect is the core mechanism controlling the formation of this stability window and proposes a new “tectonic shielding” accumulation model. This model elucidates how the thrust nappe body itself acts as a thick regional caprock, which together with lateral sealing by the fault zone forms a composite seal-cap system, ensuring in situ preservation of shale gas under a strongly tectonic background. It is concluded that local preservation units can form in the footwalls of thrust nappe belts at convergent plate margins due to stress shielding, challenging the conventional view that intensely deformed zones are unfavorable for shale gas preservation. This research not only provides a new direction and model for shale gas exploration in the tectonically complex Qinling–Dabashan region but also offers important theoretical and technical insights for unconventional hydrocarbon exploration in similar tectonic settings globally. Full article

Crop production is continually exposed to a wide range of abiotic stresses that negatively affect growth and yield, posing a severe threat to global food security. Plant growth-promoting bacteria (PGPB) promote nutrient assimilation, activate antioxidant enzymes, and stimulate phytohormone production to mitigate abiotic stress. However, the effective application of PGPB in the field depends on host colonization, soil specificity, and susceptibility to competitive microbial communities. Recently, non-thermal plasma (NTP) has emerged as a revolutionary tool for sustainable agriculture, making it a priority to develop efficient, low-cost, and eco-friendly strategies to enhance seed vitality and manage abiotic stress. Plasma-generated reactive oxygen and nitrogen species (RONS) have been shown to mediate intracellular redox homeostasis and the antioxidant defense signaling network. Furthermore, plasma stimulates MAPK cascades and stress-responsive genes such as LEA1, SnRK2, P5C, and the SOS pathway, ionic balance, and membrane stability, ultimately supporting plant stress adaptation to drought, salinity, and heavy metals. Plasma-induced RONS signaling activates PGPB functional traits such as root colonization, biofilm formation, nutrient mobilization, and plant growth-promoting activities. However, the molecular mechanisms underlying NTP-PGPB microbial multiple stress adaptation and the long-term ecological stability and biosafety of microbial communities remain inadequately resolved. Consequently, future integration of multi-omics approaches, synthetic microbial communities, and field-scale validation is required to explore the mechanistic advances of plasma-modulated microbiome interactions to enable agricultural applications. Full article

The aluminum/steel hybrid body structure represents one of the key breakthrough directions for automotive lightweighting. However, aluminum and steel differ significantly in their thermophysical properties, making it difficult to achieve high-quality joining between them using conventional fusion welding methods. To address this challenge, the present study employs ultrasonic welding technology to achieve spot welding in a steel/aluminum/steel three-layer plate configuration. The experimental welding of the three-layer sheets and interfacial phase identification were first carried out, followed by the development of an ultrasonic vibration–thermal–mechanical coupled numerical simulation model, the accuracy of which was verified through experiments. On this basis, the dynamic evolution of the temperature and stress fields during the ultrasonic welding process was systematically revealed. Furthermore, this novel engineering simulation case was introduced into the teaching of the course Engineering Finite Element and Numerical Computation yielding favorable educational outcomes. Full article

Magnetothermally responsive nanocarriers represent a promising platform for spatio-temporally controlled drug delivery by combining alternating magnetic field (AMF)-induced heating with thermally triggered cargo release. Among the available architectures, magnetite-core/mesoporous-silica-shell (Fe₃O₄@mSiO₂) nanoparticles functionalized with thermoresponsive polymer gatekeepers are particularly attractive. These systems integrate a magnetic heat source, a mesoporous drug reservoir, and temperature-dependent control of pore accessibility. This review examines the fundamental principles of magnetic hyperthermia, including heat-generation mechanisms, specific absorption rate (SAR), intrinsic loss power (ILP), AMF parameters and safety, and the interplay between Néel and Brownian relaxation. It also critically discusses core–shell synthesis and architecture, drug-loading strategies, PNIPAM-, PNVCL-, and other LCST-type gatekeepers, and the physicochemical characterization required to validate the complete nanocarrier. Evidence for combined magnetic hyperthermia and chemotherapy is assessed together with hemocompatibility, immunogenicity, oxidative stress, biodistribution, degradation, long-term retention, and clearance. Although promising magnetothermal release and therapeutic effects have been reported, evidence remains dominated by in vitro studies, with limited in vivo validation. Current clinical experience concerns locally administered iron-oxide hyperthermia rather than complete thermoresponsive Fe₃O₄@mSiO₂ drug-delivery systems. Translation will require standardized magnetothermal and release testing, reproducible scale-up, validated sterilization and endotoxin control, component-resolved pharmacokinetics, and integrated development of the nanocarrier and AMF applicator. Full article

The biological interfaces encountered by ultrasound are rarely welded in the ideal elastic sense. Around tissue–implant contacts, fibrotic capsules, thin membranes, hydrated layers, and tissue-mimicking phantoms, a weak boundary may involve finite mechanical compliance, viscoelastic memory, and local thermo-diffusive exchange. Here, we develop a forward scattering model for a plane P-wave incident from an elastic half-space onto a fractional bio-thermo-diffusive viscoelastic half-space through such an imperfect interface. Caputo-type memory is used in the viscoelastic moduli and the thermal and diffusive relaxation terms, while normal and tangential spring-layer laws describe the mechanical weakness of the contact. The formulation gives a coupled longitudinal dispersion matrix and a reduced six-amplitude interface system. In the revised flux calculation, mechanical reflection and transmission are obtained from the signed total stress–velocity work of the complete reflected and transmitted fields, so modal cross-contributions are retained. The accepted computational population contains 1326 paths and 131,361 points from sub-kilohertz frequencies to ten megahertz, with high-precision recomputation and reliability grades used where conditioning requires caution. Thermochemical quantities remain separate diagnostic channels because a physical absorption coefficient cannot be identified from the present source model. The results show parameter-dependent associations with fractional order, interface stiffness, and frequency, but they do not establish single-parameter causation. The model is therefore intended as a verification-oriented framework for future calibrated studies of weak biological interfaces, not as an experimentally validated or patient-specific predictor. Full article

Strong heterogeneity in unconventional reservoirs leads to complex fracture propagation and challenges in quantitative stimulation evaluation. This study integrates true triaxial fracturing experiments, three-dimensional CT reconstruction, multi-field coupled numerical simulation, and multiple linear regression to investigate the fracture behavior of Gulong shale (Q1, Q9) and tight sandstone under supercritical carbon dioxide (SC-CO₂) fracturing. A fracture complexity index (FCI) that incorporates fractal dimension, spatial uniformity, and aperture distribution is proposed as a quantitative metric. The results show that SC-CO₂ significantly reduces breakdown pressure and increases fracture complexity compared to water. For Q9 shale, SC-CO₂ gives a breakdown pressure of 32.91 MPa (10.46% lower than water), a fractal dimension of 2.41, and an FCI of 8.92. In tight sandstone, the SC-CO₂ breakdown pressure is 34.12 MPa, whereas water increases it to 44.50 MPa; the fractal dimension and FCI are only 2.05 and 3.40, respectively, lower than those of shale fractured with water. Multiple linear regression quantifies contribution weights: lithological weak-plane development dominates fracture complexity (41.6%), far exceeding the brittleness index. The injection rate mainly controls stimulation scale: the damage area ratio rises from 1.79% to 2.90% when the rate increases from 10 to 40 mL/min. The horizontal stress difference is key to complexity enhancement: the fractal dimension increases from 1.9230 to 1.9901 as the stress difference rises from 0 to 4 MPa. The numerical simulations further reveal the coupled thermal-hydraulic-mechanical effects. The proposed FCI-based evaluation and regression models provide a quantitative framework for optimizing SC-CO₂ fracturing design in heterogeneous unconventional reservoirs. Full article