Search Results (1,465)

Objective: Current evidence on the association between multiple trace elements and type 2 diabetes mellitus (T2DM) remains limited, particularly regarding combined effects, nonlinear dose–response patterns, and elemental interactions. This study aimed to evaluate the associations between multiple serum trace elements and T2DM using a sequential analytical strategy. Methods: A 1:1 propensity score–matched case–control study based on sex, age, and residence was conducted (637 controls, 637 T2DM cases). Serum concentrations of 18 trace elements were measured using inductively coupled plasma mass spectrometry (ICP-MS). A sequential analytical strategy was applied: LASSO regression for variable selection; logistic regression with single-element (Model 1) and multi-element (Models 2 and 3) approaches for association assessment; weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) for mixture effects; and restricted cubic spline (RCS) for dose–response patterns. Results: Lithium (Li) and tellurium (Te) showed positive associations with T2DM across multiple analytical methods, whereas boron (B), lead (Pb), and vanadium (V) showed inverse associations. WQS identified V and B as the main contributing elements. BKMR did not identify a statistically significant overall association between the mixture and T2DM. Although bivariate interaction plots suggested possible effect modification between V and Al, B, Li, Pb, and Te, formal interaction tests did not reach statistical significance. RCS showed that serum B was significantly associated with T2DM overall and exhibited a significant non-linear dose–response relationship (P-nonlinear = 0.0028). Serum V showed a linear inverse association with T2DM, and serum Li showed a linear positive association. Conclusions: Our findings suggest that Li, Te, B, and V are associated with T2DM, with the most robust evidence for Li, while the evidence for Te was less consistent. In addition, we observed a trend toward a joint association of the trace element mixture, potential effect modification at the point-estimate level between V and Al, B, Li, Pb, and Te, and distinct dose–response patterns for B, Li, and V. These findings highlight the need for further investigation of trace elements in relation to T2DM, with consideration of both individual and combined associations; future validation of these exploratory findings in larger prospective studies and independent populations is warranted. Full article

Anchors constructed in water-rich sandy-pebble strata require grout systems that can maintain material continuity and transfer tensile force effectively before groundwater-related disturbance weakens the borehole interface. This study investigated a sulphoaluminate cement-based rapid-setting grout (SAC) for PSB high-strength threaded anchors, using an ordinary Portland cement-based grout (OPC) as a reference material. Laboratory central pull-out tests were first conducted on grout cube specimens with different steel-bar diameters and bonded lengths to evaluate the steel–grout bond response. Full-scale field pull-out tests were then performed to examine the anchor–grout–ground response under water-rich ground conditions. LS-DYNA finite element models were calibrated against the laboratory and field results to interpret the governing load-transfer mechanism and to assess the influence of representative stratum resistance. The laboratory tests showed that the steel–grout bond response depended on both interfacial degradation and mortar splitting, indicating that peak bond strength should be interpreted together with failure mode and slip development. In the field tests, all anchors failed by pull-out, and the steel bar and grout body were pulled out together, showing that the full-scale response was governed mainly by the grout–ground interface rather than by steel–grout debonding. The calibrated numerical models reproduced the main load–displacement trends and supported a scale-dependent transition from steel–grout bond control at material scale to grout–ground interface control at field scale. The results provide a basis for evaluating rapid-setting grouts for high-strength anchors in water-rich sandy-pebble ground. Full article

NiCr composite coatings on stainless steel were obtained by the simultaneous deposition of Cr and Ni, using thermionic vacuum arc (TVA) technology. The main aim of this paper is to study the influence of graphite and oxygen incorporation on the structural, mechanical, and tribological properties of the resulting coatings. The deposition geometry was designed to maintain a relative constant Cr/Ni ratio while inducing a controlled compositional gradient in carbon content. An additional batch of samples was synthesized under reactive conditions by introducing a controlled O₂ flow while maintaining the same plasma parameters during deposition. The coatings were deposited on both Si wafers and AISI 304 stainless steel substrates. The elemental composition and phase structure were analyzed by scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS) and grazing-incidence X-ray diffraction (GIXRD), revealing the formation of mixed CrNi intermetallic phases, nickel carbide (Ni₃C), and, under reactive conditions, chromium and nickel oxides. Increasing the oxygen content led to a progressive structural transition from metallic–carbide mixtures to predominantly crystalline oxide phases. Tribological performance was evaluated using a ball-on-disk tribometer, and the results demonstrated a significant reduction and stabilization of the friction coefficient for oxygen-containing coatings, together with enhanced wear resistance. SEM and EDS analyses of the wear tracks confirmed the formation of protective oxide layers that effectively reduced coating removal during sliding. Nanoindentation measurements revealed a substantial increase in hardness from ~4 GPa for binary Cr–Ni coatings to ~9 GPa for ternary Cr–Ni–C films, with the highest hardness values obtained for oxygen-enriched coatings. The results highlight the synergistic role of carbon and oxygen in tailoring the microstructure and enhancing the mechanical and tribological performance of Cr–Ni-based composite coatings deposited by TVA, demonstrating their potential for protective applications under demanding operating conditions. This work demonstrates that controlled oxygen incorporation during TVA deposition can be used as an effective tool to tailor simultaneously the phase composition, surface chemistry, mechanical response, and tribological behavior of Cr–Ni–C coatings without compromising coating integrity. Full article

Significant progress has been made in exploring ultra-deep tight sandstone gas in the Tarim Basin, but sweet spot prediction remains challenging in the Keshen block of the Kuqa Depression. Based on integrated geological, experimental, and seismic data, this study characterizes the geomechanical properties and in situ stress field of the Cretaceous Bashijiqike Formation and identifies the main controls on reservoir quality. 3D geomechanical modeling and finite element simulations reveal that fracture development, stress–fracture angle, structural style, and the absence of stress concentration jointly govern reservoir favorability. Stress concentration can coexist with fracture development due to differential sandstone–mudstone deformation, leading to fracture deactivation. Favorable reservoirs occur in structural positions with extensive natural fractures, moderate principal stress–fracture angles, and low stress concentration. Coupling between in situ stress and natural fractures is the key to sweet spot prediction. The proposed geomechanical workflow improves precise identification of engineering and geological sweet spots, enhancing exploration and development efficiency in ultra-deep tight gas reservoirs. Full article

There is a growing need for high-efficiency power electronic converters that can effectively convert energy, regulate voltages, and enhance power quality in standalone power generators, as the use of renewable energy sources and battery energy storage devices increases. The quasi-impedance-source inverter (qZSI) has attracted significant interest due to its single-stage buck-boost operation, continuous input current, reduced reliance on passive elements, and increased reliability. In this paper, the control strategy and implementation of the qZSI with battery assistance for standalone photovoltaic energy generation are discussed. To analyze the operational characteristics and design the control strategy of the qZSI, the system equations are linearized around the nominal operating point to develop a small-signal model, from which the direct current (DC) side and alternative current (AC) side transfer functions are derived and used as the basis for controller design. Using the proposed model, hybrid controllers are designed to control the shoot-through duty cycle, maintain DC link voltage stability, and battery charging to achieve stable power generation. Furthermore, the SPWM technique is applied to produce AC power with minimal harmonic content and higher efficiency. Application results show stable dynamic behavior, effective battery energy management, improved voltage regulation, and reduced harmonic distortion in the output waveform. The main contribution is a low-complexity coordinated PI and PR control framework for standalone battery-assisted qZSI operation, experimentally validated under DC- and AC-side disturbances without requiring an additional battery-side power-conversion stage. Full article

Cloud data sharing allows users to outsource data storage and management to external servers, but it also raises privacy concerns when data must remain encrypted while still supporting efficient search and fine-grained access control. Attribute-based encryption with keyword search (ABE-EKS) addresses this problem by combining searchable encryption with attribute-based access policies. However, existing schemes often focus on separate aspects such as expressive search, online/offline computation, revocation, or policy protection, while controlled trapdoor delegation and inequality-based keyword predicates are less commonly considered together in an implementation-oriented Type-3 pairing setting. This paper revisits the ABE-EKS framework of Yang et al. and adapts it to the Type-3 pairing setting. The construction follows the main structure of Yang et al.’s ABE-EKS scheme, but places the group elements in the appropriate source groups for asymmetric pairings. It further supports expressive access-control and keyword-search policies, Boolean keyword predicates, inequality comparisons, and trapdoor key delegation. We also analyse its security under the honest-but-curious cloud model and implement the scheme using the Apache Milagro Cryptographic Library (AMCL). Experimental results on the Enron Email dataset demonstrate the feasibility of the proposed construction for outsourced encrypted data-sharing scenarios. Full article

During frequent starting and braking of metro vehicles, wheel–rail contact may change from pure rolling to full slip, and the frictional heat generated at the interface can induce localised rail damage such as rail burns. Because the motion state and the thermal input vary together in service, their separate contributions to the contact response are difficult to identify. To separate them, a three-dimensional elastic–plastic finite element model of a Type B metro wheel and rail was established and four cases were computed, forming a 2 × 2 factorial combination of two motion states (pure rolling and full slip) and two thermal states. The temperature field was imposed as a prescribed railhead boundary rising from 22 °C to 50 °C, applied identically under both motion states as a control variable, rather than solved from frictional heating. Under an 80 kN wheel load, the maximum rail equivalent stress of the four cases is 541.9, 596.3, 623.1 and 679.5 MPa, all exceeding the 457 MPa yield strength of U71Mn rail steel and indicating shallow localised plasticity in the contact patch. Full slip changes the peak contact pressure by less than 2% but raises the maximum rail equivalent stress by 14–15%, because the interface passes into full sliding and the high-stress zone moves towards the rail surface; the 28 °C temperature rise concentrates the contact and raises the stress by a further 9–10%. The factorial interaction term is +2.0 MPa, below 4% of either main effect. An analytical estimate shows the imposed thermal load to be a conservative lower bound for continuous sliding. Full article

Layered cathodes (LiNi_xCo_yMn_zO₂, NCM) have emerged as critical materials for batteries and energy storage fields by virtue of their high energy density. However, NCM materials undergo rapid performance degradation and severe capacity fading under harsh conditions of long-term cycling and high voltage. Currently, research regarding spent NCM materials mainly concentrates on failure analysis and modification processes at the macroscopic scale. Nevertheless, the failure mechanisms of NCM, the intrinsic processes during repair and modification, and the fundamental origins of performance improvement are generally embedded in structural evolution at the nanoscale or even atomic scale. This review first discusses the failure mechanisms of NCM. Particularly, the main content focuses on lattice distortion and layered structural instability at the lattice level, migration of nanoscale species together with performance degradation induced by side reactions at the interface level, and generation of nanocracks at the particle level. Moreover, this paper reviews the characterization methods applied at the nanometer scale, and two modification strategies are summarized, namely nanoscale coating and elemental doping. It is expected to provide theoretical references and technical insights for constructing efficient and controllable targeted modification strategies of layered NCM cathodes and developing high-performance ternary cathode materials. Full article

Operational modal analysis (OMA) is important for continuous structural health monitoring (SHM) of in-service offshore jacket platforms. In practice, long monitoring records increase the computational cost of SSI, while environmental and measurement interference can affect the recorded response. This study applies a hybrid procedure combining Kalman filtering (KF), the Random Decrement Technique (RDT), and Stochastic Subspace Identification (SSI). KF is used as a fixed-parameter preprocessing step, RDT extracts shorter free-decay signatures, and SSI is used to identify the natural frequency. The procedure is examined using a finite element (FE) model, a laboratory-scale model, and full-scale measurements from the same operating offshore platform represented by the FE model. For a representative 50 Hz record, RDT reduced the data entering SSI from 38,553 to 1200 samples (96.89%) and reduced the number of Hankel-matrix elements by 97.05%. Under identical SSI settings, the complete KF-RDT-SSI procedure required about one-fifth of the Standard SSI runtime in the benchmark environment. In the four-channel laboratory test, the dominant spectral peak remained at 6.1279 Hz before and after KF processing. KF-RDT-SSI identified 6.1204–6.1353 Hz, with a mean absolute relative deviation of 0.095% from the FFT result. The field measurements identified the fundamental natural frequency at approximately 1.56–1.57 Hz under transient and continuous operating conditions. The full-scale measurements provide the main evidence for the field applicability of the procedure. A systematic assessment under controlled noise types and signal-to-noise ratios is left for future work. Full article

This paper investigates the seismic performance of a nonlinear passive control device, namely a Bi-Stable Mass Damper–Inerter (BSMDI), designed to mitigate structural displacements. The system combines a mass damper connected to the primary structure through a bistable (snap-through) nonlinear element with a grounded inerter, enabling the exploitation of both nonlinear energy transfer mechanisms and enhanced inertial effects. The main objective of the study is to assess the effectiveness of the proposed BSMDI in reducing the maximum displacement response of structures subjected to seismic excitation. The novelty of the work lies in the synergistic integration of bistable nonlinear dynamics and inerter-based inertial amplification, together with a systematic parametric investigation aimed at identifying effective configurations in terms of both bistable parameters and inertance. The study is carried out on a two-degree-of-freedom system, in which the primary structure to be protected is represented by an equivalent single-degree-of-freedom model. This system is coupled to a mass damper through a bistable element, which is in turn connected to a grounded inerter device. A comprehensive parametric study is performed by varying the dimensionless stiffness and cubic coefficients of the bistable element, as well as the inertance ratio, while keeping the damper mass ratio small. The system performance is assessed using a displacement-based index defined as the ratio between the peak response of the controlled structure and that of the uncontrolled configuration. Performance maps and corresponding optimal curves are derived for three different seismic inputs. The present results suggest that the inerter plays a crucial role in achieving effective vibration mitigation, being significantly more effective than the damper mass alone. Overall, the proposed device appears to provide an efficient solution for seismic displacement mitigation. Full article

Cold recycled mixtures with bitumen emulsion (CRME) serving in seasonally frozen regions are susceptible to mechanical deterioration under repeated freeze-thaw (F-T) cycles, which is primarily manifested as interfacial damage and crack propagation. However, the micro-mechanical processes associated with the transmission and dissipation of frost-heaving stresses induced by water-ice phase transition within the interfacial transition zone (ITZ) between reclaimed asphalt pavement (RAP) and asphalt mortar remain to be further characterized. In this study, a numerical simulation approach coupling frost heave effects with the phase transition of water-ice particles was developed based on X-ray computed tomography (CT) and the discrete element method (DEM), and the micro-mechanical parameters of the RAP-asphalt mortar ITZ were determined through laboratory experiments. Combined with acoustic emission (AE) monitoring, the damage evolution characteristics of cold recycled mixtures and the associated interfacial damage mechanisms under freeze-thaw action were systematically investigated. The results indicate that the optimal micro-parameters of the RAP-asphalt mortar ITZ can be taken as approximately 85% of those of virgin asphalt mortar. After 20 freeze-thaw cycles, the number of shear cracks and tensile cracks in ITZ on RAP surface reached 493 and 92, respectively, which were much higher than 11 and five on the surface of new aggregate. ITZ was the main control weak area of freeze-thaw damage. Compared with the unfrozen specimens, the minimum effective contact number of mortar decreased by 1.63%, 4.52% and 8.52% respectively after 5, 10 and 20 freeze-thaw cycles, and the total effective contact number decreased from 75,842 to 69,383. Freeze-thaw cycles significantly reduce the strain energy storage capacity of CRME: the maximum energy storage capacity of the adhesive spring decreased from 2.15 J in the non-freeze-thaw state to 1.28 J in 10 cycles (a decrease of 40.47%) and 1.16 J in 20 cycles (a decrease of 46.05%), and the damage mode changed from brittle fracture to interface-controlled energy dissipation. The proposed water-ice phase transition-based DEM framework provides a reliable numerical tool for investigating freeze-thaw damage mechanisms and supporting durability-oriented design of cold recycled pavement materials. Full article

Driven by the engineering requirement for high acoustic stealth of unmanned underwater vehicles (UUVs), this paper investigates the electromagnetic vibration of an 8-pole, 48-slot, surface-mounted permanent magnet synchronous motor (SPMSM) employed in the propulsion system through multi-physics coupling analysis and experimental testing. First, analytical calculations of electromagnetic force waves are performed based on the Maxwell stress tensor method and the magnetomotive force–permeance method to analyze the spatial orders, temporal orders, and sources of the harmonics. Then, a two-dimensional motor model is established using ANSYS electromagnetic field simulation software to investigate the temporal and spatial characteristics of electromagnetic force waves under both no-load and on-load conditions. Fourier decomposition is applied to obtain the amplitude-frequency characteristics, thereby verifying the correctness of the analytical results. Subsequently, three-dimensional models of the stator core and the complete stator assembly are constructed in the physical field, and their modal frequencies and mode shapes are obtained through simulation. On this basis, harmonic response analysis is conducted by applying electromagnetic force waves to the stator teeth, and vibration simulations are performed in ANSYS Workbench to acquire vibration characteristics. Vibration experiments are then carried out at multiple rotational speeds, and the experimental results are compared with the simulation results to validate the feasibility and accuracy of the finite element modeling approach. Since the measured motor vibration results are influenced not only by electromagnetic excitation forces, but also by various factors such as mechanical structure, instrument installation, and fixture conditions, while the simulation model in this paper inevitably simplifies damping, housing details, inverter control effects, and considers only the effect of radial electromagnetic forces, there exists a certain discrepancy between the simulated and measured motor vibration acceleration results. However, the main vibration trends in the low-frequency range below 800 Hz are basically consistent, particularly at the second and fourth harmonic frequencies, where the vibrations are electromagnetic vibrations caused by radial electromagnetic force waves, with relative errors between the measured and simulated values of 18% and 25%, respectively. This finite element model can be used for preliminary design evaluation of PMSMs and rapid prediction of electromagnetic vibration, providing researchers with a convenient and practical research approach and methodology. Finally, by analyzing factors that may influence motor vibration, this paper proposes design modifications to the stator structure and air-gap width, providing an optimized solution for reducing electromagnetic vibration of the permanent magnet synchronous motor and avoiding resonance. Full article

Organic matter enrichment in marine–continental transitional shales is influenced by volcanism, continental weathering, and paleoceanographic evolution, but their interactions during the Late Paleozoic Ice Age (LPIA) remain unclear. Mineralogical, elemental, and organic geochemical data from the Upper Carboniferous Yanghugou Formation, western Ordos Basin, were used to reconstruct volcanic input, weathering intensity, productivity, redox conditions, and organic carbon accumulation. High Hg/TOC, Zr/Al₂O₃, and Zr/Cr ratios indicate strong volcanic input during early deposition, followed by an upward decline. Chemical Index of Alteration values of 76.5–91.5 increase upward, indicating intensified chemical weathering under warmer and more humid conditions. Increasing C_org/P, Mo_EF, and U_EF values record a shift from oxic–suboxic to predominantly anoxic bottom waters. The weak relationship between productivity proxies and TOC suggests that volcanic fertilization was not the main control on organic matter enrichment. Instead, negative δ¹³C_org values, high Al₂O₃ contents, organic matter–clay associations, and reducing conditions indicate that enhanced terrestrial organic matter input and improved preservation jointly promoted organic carbon accumulation. Volcanism likely intensified climatic warming and weathering, whereas subsequent organic carbon burial contributed to atmospheric CO₂ drawdown and climatic feedbacks during the LPIA. Full article

Torque-limiting mechanisms are safety-critical elements in mechanical, automotive, robotic, aerospace and medical systems, where controlled torque transmission is required to avoid overload failure. However, the influence of dent–slot geometry on torque stability, variability and tolerance sensitivity remains insufficiently quantified. This study examines the effects of dent height, dent angle and spring plate thickness on the torque response of a compact elastic, shape-dependent torque-limiting mechanism. An integrated methodology comprising conceptual design, mathematical modelling, theoretical analysis, finite element analysis, manufacturability assessment, material characterisation, dynamic testing and VIKOR-based decision-making was implemented. Five feasible spring-drive plate configurations were investigated using two dent heights, two dent angles and two spring plate thicknesses. Material and interface properties for the Ck67–SINT D39 tribological pair were determined through tensile, flexural and friction tests, while dynamic torque and output-force data were obtained using a dedicated test bench and statistically evaluated after Chauvenet-based removal of isolated peak values. The mathematical, theoretical, numerical and experimental results showed close agreement, with torque deviations below approximately 1.5% for the main comparison metrics. Increasing dent height from 1.40 to 1.80 mm reduced relative torque variability by 34.6%, whereas reducing the dent angle from 110° to 90° increased relative torque variability by 95.0%. Configuration A2 provided the best balance, confirming dent geometry as a controllable design variable. Full article

Filament heating voltage governs thermionic electron emission in electron-beam guns, but its influence on weld formation under fixed electron-beam welding settings has received limited quantitative investigation. In this study, Ti-6Al-4V thin sheets were welded at filament heating voltages of 2.8–3.4 V, while the accelerating voltage, beam current, focusing current, and welding speed were kept constant. Weld cross-sections were characterized experimentally, and the resulting thermal process was analyzed using a simplified cathode-emission calculation and finite element thermal analysis. A clear change in weld penetration behavior was observed within approximately 3.2–3.3 V. The weld aspect ratio increased from approximately 0.4 below this region to approximately 0.6 at 3.3 V and further to approximately 0.63 at 3.4 V. Concurrent changes in the required bias voltage, calculated equivalent cathode area, and weld geometry were consistent with a change toward a more stable cathode operating condition. The weld-geometry changes were also consistent with a change in the effective beam-energy distribution, although the beam profile was not measured directly. These results show that filament heating voltage should be treated as an independent equipment-side control variable even when the main electron-beam welding settings remain unchanged. Although the specific transition range depends on the electron gun, beam-current setting, and cathode condition, the electrical-response-based identification approach may provide a practical method for identifying the filament operating range when direct beam diagnostics are unavailable. Full article