Search Results (141)

Classical Munk-type added-mass modeling remains a fundamental tool in airship flight dynamics because the displaced fluid mass is comparable to the vehicle mass and contributes directly to the generalized inertia. This paper investigates the applicability limits of classical Munk-type modeling for slender airships and develops a geometry-sensitive generalized framework based on actual hull contour information. The proposed formulation preserves consistency with the classical ellipsoidal limit while introducing discrepancy measures derived from the sectional area distribution and its longitudinal moment. The model is organized into a strict potential-flow added mass layer and a separate correction layer so that geometry-sensitive inertial effects are not conflated with non-potential aerodynamic corrections. Representative hulls are used to quantify the structural error of equivalent-ellipsoid approximations, and the Lotte airship is selected for a regularized literature-based assessment using published static and quasi-static aerodynamic coefficient curves. For the Lotte assessment case, the results show that the geometry-sensitive regularized model improves the representation of body-fixed normal force and pitching moment coefficient trends relative to the corresponding classical ellipsoidal baseline, with the clearest improvement in the pitching moment response. The analysis further indicates that the discrepancy associated with the second axial area moment is more influential for the moment response than the maximum thickness location parameter. Full article

Air quality assessment for atmospheric particulate matter (PM) faces significant metrological challenges due to the lack of Certified Reference Materials and sampler design discrepancies. This study evaluates the comparability of the EN 12341 gravimetric reference method using field data from a national interlaboratory comparison organized by the Italian Institute for Environmental Protection and Research (ISPRA) at Castel Romano with 18 Italian regional environmental agencies. The results revealed systematic deviations driven primarily by weather sensitivity—where relative humidity and precipitation compromised PM thermodynamic and mass stability—and, to a lesser extent, a minor filter matrix effect. Because gravimetric measurements provide the sole traceability source for automated measurement systems (AMS), these biases pose potential risks under Directive (EU) 2024/2881. The post-2030 regulatory framework drastically tightens AMS residual uncertainty budgets for daily and annual PM₁₀ and PM_2.5 metrics. Near these lower limits, unmitigated humidity effects and declining PM concentrations geometrically amplify residual errors in EN 16450 orthogonal regression calculations, potentially increasing equivalence test failures for certain instruments. To safeguard network data validity and legal defensibility by 2030, agencies should adopt Best Available Techniques (BAT) for sampling and filter conditioning, upgrade QA/QC protocols, and train technical personnel. Minimizing ground-level uncertainty is also crucial for atmospheric modeling and satellite retrieval validation. Full article

Background/Objectives: Antipsychotic-induced hyperprolactinemia may adversely affect skeletal health through suppression of the hypothalamic–pituitary–gonadal axis; however, the independent association between circulating prolactin and bone mineral density (BMD) remains uncertain. Methods: This cross-sectional study examined the association between serum prolactin concentration and BMD Z-scores among women with schizophrenia receiving prolactin-raising antipsychotics. Sixty-eight women underwent serum prolactin measurement and dual-energy X-ray absorptiometry at the lumbar spine, femoral neck, and total hip. Because prolactin concentrations were right-skewed, natural-log-transformed prolactin was used in linear regression analyses. Multivariable models adjusted for age, body mass index (BMI), duration of prolactin-raising antipsychotic exposure, chlorpromazine-equivalent dose, and physical activity, with heteroskedasticity-robust standard errors. Results: Median serum prolactin concentration was 44.51 ng/mL (IQR 16.36–78.37). Serum prolactin was not independently associated with BMD Z-score at the lumbar spine (adjusted β = 0.196, 95% CI −0.212 to 0.605; p = 0.340), femoral neck (β = 0.157, 95% CI −0.142 to 0.456; p = 0.298), or total hip (β = −0.224, 95% CI −0.587 to 0.139; p = 0.221). Higher BMI was positively associated with femoral neck and total hip Z-scores, while physical activity was positively associated with BMD Z-scores at all three sites. In a sensitivity analysis restricted to risperidone-treated participants (n = 60), serum prolactin remained unassociated with BMD Z-scores at all sites. Conclusions: In this cohort, contemporaneous serum prolactin concentration was not independently associated with BMD Z-scores. These findings support a multifactorial approach to skeletal health and warrant confirmation in larger longitudinal studies incorporating cumulative prolactin exposure and endocrine and bone-turnover markers. Full article

Driven by China’s “Dual Carbon” strategy, medium-deep closed-loop geothermal energy has become a mainstream clean heating technology owing to the advantage of “heat extraction without groundwater production”. However, its large-scale application is restricted by low single-well heat output and an unclear matching mechanism between working fluids and wellbores. Taking sandstone geothermal reservoirs in Dezhou, Northwestern Shandong Depression, as the research object, a 3D coupled heat transfer model of the wellbore–reservoir was established via COMSOL Multiphysics. The heat transfer characteristics of water and CO₂ under variable injection temperature, mass flow rate and wellbore layout were compared. The results show that: (1) injection temperature dominates the heat extraction performance of water, which matches branched wells and delays overall reservoir thermal depletion during long-term exploitation; (2) CO₂ performance is highly sensitive to mass flow rate and suitable for connected wells, and an asymmetric geothermal field with “cooled injection zone and heated production zone” forms under a high flow rate; (3) limited by low specific heat capacity, CO₂ delivers lower heat power at an identical flow rate, while equivalent heat yield can be achieved when its flow rate doubles that of water. This study clarifies matched development schemes for two working fluids and provides a theoretical reference for optimized exploitation of closed-loop geothermal systems in sandstone reservoirs in Northwestern Shandong. Full article

Thermal transpiration enables a Knudsen pump to transport gas without moving components. An axial-integration formulation based on pre-computed transport coefficients from the linearized Shakhov kinetic model is applied to a single-stage unit comprising a circular microchannel and a circular macrochannel in series, with opposite wall-temperature gradients. The pressure-generation and gas-transport capabilities are characterized by the maximum pressure difference or thermomolecular pressure difference (TPD), the maximum mass flow rate, the equivalent TPD, the equivalent flow resistance, and the complete mass-flow-rate–pressure-difference characteristics. The principal quantitative calculations cover temperature differences ranging from 10 to 50 K, while the 75 and 100 K cases are retained only to assess the persistence of the calculated trends. The formulation reproduces benchmark experimental TPD data with a maximum absolute relative deviation of 12.5% and a mean absolute relative deviation of 6.7%, and shows excellent agreement with numerical data from the literature, with deviation below 1%. A decomposition of the microchannel and macrochannel contributions shows that a macrochannel contributing little to the total equivalent flow resistance may nevertheless produce appreciable reverse thermal transpiration. At the baseline condition of the study and for an inlet pressure $P_i=10 \mathrm{kPa}$, the macrochannel contributes only 0.37% of the total equivalent flow resistance but cancels 15.2% of the microchannel equivalent TPD. Over $P_i=1\text{–}50 \mathrm{kPa}$, the temperature-difference sensitivity of the TPD ranges from 0.93 to 1.05, whereas the microchannel-radius sensitivity varies from −0.41 to −1.62. For the maximum mass flow rate, the microchannel-radius sensitivity ranges from 2.06 to 2.56 and the microchannel-length sensitivity remains close to −1, while the macrochannel-length effect is negligible. Increasing the macrochannel radius improves both limiting outputs, i.e., TPD and maximum mass flow rate, but with progressively diminishing benefits from further enlargement of the macrochannel. These results provide a quantitative basis for preliminary dimension selection while explicitly identifying the limitations associated with linearization, finite channel length, fully developed flow, and neglected interface losses. Full article

Applied engineering studies that use evolutionary multi-objective optimisation (MOO) rarely report confidence bounds on the Pareto-optimal solutions they recommend. This paper presents a four-stage sensitivity-analysis protocol that supplies them: cross-algorithm benchmarking, Friedman and Bonferroni-corrected Wilcoxon testing, hyperparameter sensitivity analysis, and ISO/IEC GUM-compliant uncertainty propagation. The protocol is first validated on the ZDT1, ZDT3 and DTLZ2 benchmarks (n = 2–12 decision variables), then demonstrated on an enclosed screw-conveyor design using Discrete Element Method (DEM) surrogates built by Response Surface Methodology (RSM). On the benchmarks, it correctly identified both algorithmic equivalence (MOGA and NSGA-II indistinguishable on four of five instances) and MOEA/D’s characteristic weakness on the disconnected ZDT3 front, whose hypervolume degraded most with dimensionality. For the engineering case, MOGA matched NSGA-II (p = 0.47–0.79) and remained within 0.5% hypervolume of SMS-EMOA over 12 runs, while hyperparameter variation stayed below 1% (max CV = 0.962%). DEM achieved 8.2% mean absolute percentage error for mass flow rate across 42 CCD operating conditions. The MOGA-optimised 100 mm pitch (4.86°, 138.86 rpm) delivered 0.416 kg/s at 6.95 N·m, a specific energy consumption of 0.0675 kWh/tonne and a 63.0% reduction against the 75 mm baseline. Full article

Background/Objectives: Essential oils (EOs) are complex mixtures extracted from plants. The aim of this study was to evaluate the chemical composition, antioxidant and antimicrobial properties, as well as in vivo toxicity against Drosophila melanogaster of the EOs extracted from Achillea millefolium L. (AM), Mentha longifolia L. (ML), and Thymus serpyllum L. (TS) from the mountains in Sibiu County, Romania. Methods: EOs were extracted by hydrodistillation. Their phytocompounds were determined by Gas Chromatography–Mass Spectrometry. Antioxidant potential was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS), and ferric-reducing antioxidant power (FRAP) assays. Antibacterial action was measured against eight pathogenic bacteria. An in vivo D. melanogaster diet-dependent viability assay was conducted to assess the toxicity of the EOs. Results: Chamazulene (49.72%), pulegone (36.20%), and thymol (42.11%) were the most abundant constituents of the AM, ML, and TS EOs, respectively. All tested EOs exerted antioxidant activity, with TS EO being the most efficient in the DPPH (98.19% inhibition) and ABTS (1.82 mmol Trolox equivalent (TE)/mL EO) scavenging assays, while AM EO performed best in the FRAP assay (66.70 μmol TE/mL EO). Against TS EO, Bacillus subtilis was the most sensitive, with an inhibition zone of 37 mm. A dose-dependent decrease in the viability of D. melanogaster L. was observed when their diet was supplemented with AM, ML, and TS EOs. Conclusions: The analyzed EOs demonstrated antioxidant and antimicrobial effects, suggesting their potential applications in various fields. However, due to their toxicity, an in-depth analysis is required before introducing such products in therapy. Full article

Fly ash-metakaolin geopolymer has considerable potential for low-carbon and high-strength applications. However, its performance is highly dependent on preparation parameters and curing conditions, and its mix proportion optimization and nano-modification mechanism still require further clarification. In this study, under the condition that the mass ratio of metakaolin to fly ash was fixed at 9:1, an L₁₆ (4⁵) orthogonal experiment was carried out using nano-SiO₂ content, liquid-to-solid ratio, alkali equivalent, sodium silicate modulus, and curing temperature as independent variables. Range analysis and analysis of variance were employed to investigate the response patterns of slurry fluidity, setting time, and compressive strength under variations in these factors, while XRD, SEM-EDS, and FTIR were used to reveal the modification mechanism of nano-SiO₂. The results show that the early-age compressive strength is governed by alkali equivalent, whereas the later-age strength is jointly affected by multiple factors, with the differences among their effects gradually decreasing. Alkali equivalent and liquid-to-solid ratio have comparable effects on slurry fluidity, with contribution rates of 33.83% and 30.97%, respectively. Setting time is most sensitive to changes in sodium silicate modulus, which contributes 92.76% and 90.54% to the initial and final setting times, respectively. After the incorporation of an appropriate amount of nano-SiO₂, the amorphous gel characteristics, Si-O-T bonding structure, and fracture-surface compactness of the specimens were all enhanced. However, excessive incorporation tends to cause particle agglomeration and increase the water demand of the system, weakening the continuity of geopolymerization. The specimen with better overall performance was prepared with 1% nano-SiO₂, a liquid-to-solid ratio of 0.84, an alkali equivalent of 24%, and a sodium silicate modulus of 1.4, and cured at 40 °C. Full article

This study presents a numerical comparison of dimensional and non-dimensional implementations of the classical benchmark problem of steady natural convection in a two-dimensional differentially heated square cavity over the Rayleigh-number range 10³ ≤ Ra ≤ 10¹². The novelty of this work lies in the systematic comparison of both formulations under identical numerical conditions, providing an implementation-oriented assessment of their benchmark accuracy, mesh sensitivity, continuation strategy, and computational efficiency. The governing equations of mass, momentum, and energy conservation were solved under the Boussinesq approximation using primitive variables and the finite-element method. Since both formulations are theoretically equivalent descriptions of the same physical problem, the purpose of this work is not to reassess their physical validity, but to examine their numerical behavior under identical benchmark conditions in terms of mesh sensitivity, continuation strategy, benchmark accuracy, and computational efficiency. In the dimensional implementation, temperature differences of 1, 10, 25, and 50 K were considered, and the corresponding cavity lengths were determined from the Rayleigh-number definition. The main calculations were performed with ΔT = 25 K, while ΔT = 50 K was retained only as an exploratory sensitivity case. Boundary-layer refinement was applied along the vertical walls over the range 10³ ≤ Ra ≤ 10¹². The results show that, once the near-wall gradients are properly resolved, both implementations predict essentially identical average Nusselt numbers, with a maximum relative difference of 0.022%. Temperature contours, stream-function distributions, and centerline profiles also exhibited the same structural behavior in both cases. For the reference mesh, the dimensional implementation exhibited a lower computational cost than the non-dimensional implementation, resulting in an approximately 31% reduction in computation time. These results demonstrate that solving the governing equations directly in dimensional variables provides a numerically efficient and physically interpretable alternative while preserving the benchmark accuracy of the classical non-dimensional formulation. Full article

Background: The timing of perceived exertion assessment within a resistance training set may influence physiological adaptation; this study aimed to directly compare first-repetition (RPE-1) and last-repetition (RPE-last) monitoring strategies applied to functional, neuromuscular, body composition, and cardiometabolic adaptations during elastic band resistance training in older adults. Methods: Forty sedentary older adults (n = twenty per group, sex-balanced) were randomly assigned to RPE-1 or RPE-last using the OMNI-RES elastic band scale during a 16-week, open-label high-intensity elastic band resistance training program, with blinded outcome assessment and data analysis; three withdrew during the intervention (RPE-1, n = 2; RPE-last, n = 1), and all forty randomized participants were retained in the intention-to-treat analysis via baseline carry-forward. Functional capacity, isokinetic knee and elbow strength (60 and 180°/s), DXA-assessed body composition, and fasting cardiometabolic biomarkers were evaluated pre- and post-intervention. Between-group effects were analyzed using ANCOVA with Benjamini–Hochberg false discovery rate (FDR) correction, whereas functional equivalence was assessed using Welch-corrected two one-sided tests (TOST) with percentile bootstrap against published minimum clinically important difference (MCID) margins. Results: Both groups improved significantly across most outcomes. For the primary outcomes, RPE-1 was associated with greater improvements across all eight isokinetic strength conditions after FDR correction, with adjusted between-group differences ranging from +7.86 to +18.38 Nm in favor of RPE-1, and all 95% CIs excluding zero (ηp² = 0.14–0.37). The Welch-corrected TOST demonstrated functional equivalence between monitoring strategies for all four functional outcomes in the primary intention-to-treat analysis. However, the pre-specified complete-case sensitivity did not confirm equivalence in the 30-Second Chair Stand Test, indicating that this outcome was sensitive to the handling of missing data. Among secondary exploratory outcomes, RPE-1 also was associated with greater improvements in DXA-assessed fat mass (adjusted difference—−1.33 kg; 95% CI—−2.02 to −0.63; ηp² = 0.29) and lean mass (+0.42 kg; 95% CI—0.02 to 0.83; ηp² = 0.11), high-density lipoprotein cholesterol (+5.11 mg/dL; 95% CI—1.52 to 8.69; ηp² = 0.18), and low-density lipoprotein cholesterol (−16.99 mg/dL; 95% CI—−23.22 to −10.76; ηp² = 0.45). Conclusion: RPE-1 appeared to confer greater benefits for maximizing neuromuscular strength, whereas RPE-last provides an equally valid alternative when preserving physical independence is the primary objective. Full article

High-g accelerometers are in high demand across sectors such as aerospace, defense, and industrial inspection. This paper presents a MEMS accelerometer based on graphene piezoresistors, designed for precise acceleration measurement under sudden impacts, intense vibrations, and extreme conditions, such as engine fault diagnosis and weapon impact testing. A step-by-step structural optimization and simulation analysis were conducted using finite-element simulation. Taking the peak strain at the beam root, the first-order natural frequency, and the maximum equivalent stress as optimization objectives, progressive parametric optimization was sequentially performed on four progressive architectures: a simple beam, a beam mass, a beam mass with stress concentration grooves, and a beam mass with stress concentration grooves and symmetric masses. The results indicate that the introduction of a central mass enhances the peak strain by more than 15 times compared to the simple beam. The addition of stress concentration grooves further increases the strain by approximately 30%. Finally, the incorporation of symmetric masses yields a further 9% strain enhancement while reducing cross-axis sensitivity by 5.6%, effectively suppressing off-axis interference. The final structure achieves maximized strain while maintaining a first-order natural frequency above 200 kHz, with the maximum equivalent stress staying within the allowable limit. This optimal comprehensive performance provides essential technical support for high-performance graphene-based accelerometers. In addition to the mechanical structural optimization, the graphene piezoresistors were treated as surface sensing regions at the beam-root locations, and the area-averaged longitudinal strain was extracted as the input of a piezoresistive transduction model. The simulated strain was converted to resistance variation and bridge output voltage using a graphene gauge-factor-based readout model incorporating contact-resistance effects, thereby providing a sensor-level electromechanical performance estimation for the proposed high-g accelerometer. Full article

This paper proposes a norm-based admissibility criterion formulated in the frequency domain for evaluating whether translational and rotational motion amplitudes of a ship moored at a quay remain within operational limits prescribed by port authorities. The approach is built on a linear six-degree-of-freedom model that includes hydrodynamic added-mass and radiation-damping effects, wave excitation forces, and aerodynamic wind loads, as well as linearized reactions of mooring lines and quay fenders, including an equivalent viscous representation of hull–fender friction. Instead of explicitly inverting the full system matrix to compute the complete response, the admissibility assessment is derived from row-wise norm bounds of the frequency-domain system, yielding a computationally efficient admissibility criterion for compliance with motion limits. The criterion naturally enables a port-oriented decision index and an operational safety margin that can be evaluated for each degree of freedom and used to compare alternative mooring arrangements. Numerical verification is performed for a bulk carrier under storm wave excitation and different loading conditions, demonstrating the sensitivity of admissibility to mooring geometry and pretension. The results confirm that the proposed criterion provides a practical engineering tool for rapid go/no-go decisions regarding cargo operations and supports the selection of mooring arrangements that improve operational robustness under adverse environmental loading conditions. In addition, a Monte Carlo-based uncertainty analysis is performed to evaluate the robustness of the proposed admissibility criterion with variable mooring stiffness and damping parameters. The proposed criterion is intended as a rapid engineering screening tool to complement conventional frequency-domain response analysis. Full article

Tomato yellow leaf curl virus (TYLCV) is a major threat to tomato production, creating a need for sensitive, low-cost detection methods that can be applied to early symptomatic or low-viral-load samples. Recombinant antigen configuration may influence serological assay development, although the specific contribution of multiple-cloning-site (MCS)-derived intermediate sequences remains uncertain. In this study, a recombinant Trx-His-coat protein (CP) fusion antigen was produced using an MCS-free direct-fusion construct that retained the Trx-His tag while removing the MCS-derived intermediate sequence, followed by gradient refolding. No direct comparison with linker-containing, tag-cleaved, or tag-free antigen constructs was performed. The purified antigen was used to immunize rabbits and generate a high-titre polyclonal antibody (pAb). The resulting indirect enzyme-linked immunosorbent assay (ELISA) achieved a theoretical limit of detection of 1.8 ng/mL and an estimated pre-dilution equivalent the limit of detection (LOD) of 72 ng/mL after sample dilution. The assay showed favourable tolerance to crude tomato leaf matrices, with spike-recovery rates of 95.45–100.40%. In a preliminary evaluation using a balanced panel of 32 field-collected samples, ELISA absorbance correlated with droplet digital PCR quantification (R² = 0.9819) and plant disease index values (R² = 0.9774). Liquid chromatography–tandem mass spectrometry (LC-MS/MS) peptide mapping and AlphaFold2-based modelling were used only to provide preliminary computational context for antigen interpretation. The assay showed cross-recognition toward Tobacco curly shoot virus (TbCSV), indicating that it should not be considered strictly TYLCV species-specific. Therefore, this assay may support preliminary serological screening under the tested conditions, whereas molecular confirmation remains necessary when species-level identification is required. Full article

The expansion of deep-buried tunnels into complex geological settings has heightened the risk of encountering high-pressure gas strata. This study addresses a critical knowledge gap regarding safe rock-pillar thickness when tunneling through high-pressure CO₂-bearing formations, motivated by a 2.3 MPa CO₂ blowout event encountered during the geological investigation of a deep railway tunnel in western China. Numerical simulations were conducted using Phase2/RS2 (2D plane-strain models for the tunnel floor) and FLAC3D (3D models for the tunnel face) to evaluate plastic zone evolution and displacement responses under prescribed equivalent static CO₂ pressure conditions and rock-mass degradation scenarios. The simulations represent a mechanical assessment under a prescribed pressure condition rather than a fully coupled gas-flow–mechanical analysis. Under the equivalent static CO₂ pressure assumption, the calculated plastic zone depth increased from 10.2 m in the no-pressure case to 17.4 m under the 2.3 MPa pressure condition, while the maximum floor displacement increased from 0.4 cm to 11.0 cm. These results represent a conservative mechanical response under the adopted pore-pressure efficiency assumption and should not be interpreted as a direct simulation of gas compressibility, capillary effects, pressure diffusion, or gas–water two-phase behavior. Under the adopted parametric degradation scenarios, rock-mass strength reduction further increases the calculated plastic zone depth and displacement. In the strong degradation case, the plastic zone depth reaches 32.6 m and the maximum displacement reaches 19.0 cm. These values should be interpreted as sensitivity-analysis results for the assumed degraded rock-mass conditions, rather than as general predictions for all fractured or weathered rock masses. For face stability, the critical coalescence distance between excavation-disturbed and high-pressure-affected zones was identified as 15 m for intact rock, advancing to 20 m and 30 m under 10% and 20% strength reductions, respectively. Based on these findings, preliminary conservative reference values are proposed for risk identification when tunneling toward high-pressure CO₂-bearing fractured zones. The calculated floor plastic zone depth of 17.4–32.6 m and the face coalescence distance of 15–30 m should be interpreted as mechanical warning indicators under the adopted equivalent static pressure assumption. These values have not yet been validated by construction-stage monitoring data and should therefore be updated using gas-pressure measurements, deformation monitoring, support response, drainage performance, and field back-analysis during tunnel construction. Full article

Thin, steeply dipping orebodies hosted in kaolinized altered fault zones are difficult to mine safely because of weak rock mass integrity, water sensitivity, and limited self-supporting capacity. This study investigates the F20 ore-bearing altered structural zone at Changtai Mining and develops an artificial floor design for downward drift-and-fill mining. Engineering geological characterization, rock mass quality evaluation, mechanical analysis, and three-dimensional numerical simulation were combined to assess floor-bearing requirements and regional recovery stability. The results show that the wall rocks are grade III, whereas the ore-bearing altered zone is grade IV and represents the controlling weak component. For the preferred 3.5 m × 3.5 m drift, an equivalent artificial floor bearing thickness of about 1.0 m is required. Numerical evaluation indicates that supported drifts remain stable, but crosscut–drift intersections are the main deformation and damage concentration zones. A representative 0.5 m drift offset significantly weakens the load-transfer path of the floor–rock system. The proposed vertically aligned, short drift, rapid backfill scheme with a reinforced composite artificial floor provides a practical basis for safe recovery of weak kaolinized altered orebodies. Full article