Search Results (2,361)

Currently, resin polymer anchoring agents are widely used for bolting support in coal mine roadways to anchor the bolts to the surrounding rock mass. However, due to the relatively low strength of the resin anchoring agent itself, the required anchoring length tends to be excessively long. Based on this, this paper proposes the use of resin concrete as a replacement for resin. Compared to resin anchoring agents, resin concrete offers greater mechanical interlocking force with anchor rods, which can reduce the theoretical anchoring length. To systematically investigate the influence of factors such as the diameter and anchorage length of Glass Fiber-Reinforced Polymer (GFRP) bolt on the bond behavior between GFRP bolts and resin concrete, 33 standard pull-out tests were designed and conducted in accordance with the CSA S807-19 standard. Taking the 18 mm-diameter bolt as an example, when the bond lengths were 2D, 3D, 4D, and 5D, the average bond strengths were 41.32 MPa, 39.18 MPa, 38.84 MPa, and 37.44 MPa, respectively. This represents a decrease of 5.18%, 6.00%, and 9.39% for each subsequent increase in bond length. The results indicate that the bond strength between GFRP anchors and resin decreases as the anchorage length increases. Due to the shear lag effect, the average bond strength also decreases with increasing anchor diameter. Taking a 5D (where D is the anchor diameter) anchorage length as a reference, the average bond strengths for anchor diameters of 18 mm, 20 mm, 22 mm, and 24 mm were 37.44 MPa, 33.97 MPa, 32.18 MPa, and 31.50 MPa, respectively. The corresponding reductions compared to the 18 mm diameter case were 9.27%, 14.05%, and 15.87%. Based on the experimental results, this paper proposes a bond–slip constitutive model between the bolt and resin concrete, which consists of a rising branch, a descending branch, and a residual branch. A differential equation relating shear stress to displacement was established, and the functions describing the variation in displacement, normal stress, and shear stress along the position were solved for the ascending branch. Although an analytical solution for the differential equation of the descending branch was not obtained, it will not affect the subsequent derivation of the theoretical anchorage length for the GFRP bolt–resin concrete system, as structural components in practical engineering are not permitted to undergo excessive bond-slip. Full article

The complex jet-ground interactions of Short Take-off and Vertical Landing (STOVL) aircraft are critical to flight safety and performance, yet studying them with traditional full-scale wind tunnel tests is prohibitively expensive and time-consuming, hindering design optimization. This study addresses this challenge by developing and numerically verifying a “pressure ratio–momentum–geometry” multi-dimensional similarity framework, enabling accurate and efficient scaled-model analysis. Systematic simulations of an F-35B-like configuration demonstrate the framework’s high fidelity. For a representative curved nozzle configuration (e.g., the F-35B three-bearing swivel duct nozzle, 3BSD), across scale factors ranging from 1:1 to 1:15, the plume deflection angle remains stable at 12° ± 1°. Concurrently, axial force (F) and mass flow rate (Q) strictly follow the square scaling relationship ($F\propto 1/n^2, Q\propto 1/n^2)$, with deviations from theory remaining below 0.15% and 0.58%, respectively, even at the 1:15 scale, confirming high-fidelity momentum similarity, particularly in the near-field flow direction. Second, a 1:13.25 scale aircraft model, constructed using Froude similarity principles, exhibits critical parameter agreement (intake total pressure and total temperature) of the prototype-including vertical axial force, lift fan mass flow, and intake total temperature—all less than 1.5%, while the critical intake total pressure error is only 2.2%. Fountain flow structures and ground temperature distributions show high consistency with the full-scale aircraft, validating the reliability of the proposed “pressure ratio–momentum–geometry” multi-dimensional similarity criterion. The framework developed herein has the potential to reduce wind tunnel testing costs and shorten development cycles, offering an efficient experimental strategy for STOVL aircraft research and development. Full article

Solid oxide electrolysis cells (SOECs) have emerged as a promising technology for efficient energy storage and CO₂ utilization via H₂O–CO₂ co-electrolysis. While most previous studies focused on planar or tubular configurations, this work investigated a novel flat, tubular SOEC design using a comprehensive 3D multi-physics model developed in COMSOL Multiphysics 5.6. This model integrates charge transfer, gas flow, heat transfer, chemical/electrochemical reactions, and structural mechanics to analyze operational behavior and thermo-mechanical stress under different voltages and pressures. Simulation results indicate that increasing operating voltage leads to significant temperature and current density inhomogeneity. Furthermore, elevated pressure improves electrochemical performance, possibly due to increased reactant concentrations and reduced mass transfer limitations; however, it also increases temperature gradients and the maximum first principal stress. These findings underscore that the design and optimization of flat tubular SOECs in H₂O–CO₂ co-electrolysis should take the trade-off between performance and durability into consideration. Full article

Cell towers play a key role in providing telecommunications infrastructure, especially in remote mountainous regions. This paper presents an approach to the efficient design of 42-metre-high cell towers intended to install high-power equipment in remote mountainous regions of the Carpathians (750 m above sea level). The region requires rapid deployment of many standardized towers adapted to geographical features. The main design challenges were the limited space available for the base, the impact of extreme weather conditions, and the need for a fast project implementation due to the critical importance of ensuring stable communication. Special methodological attention is given to how the transition between pyramidal and prismatic segments in cell tower shafts influences overall structural performance. The effect of this geometric boundary on structural efficiency and material usage has not been addressed in previous studies. A dedicated investigation shows that positioning the transition at a height of 33 m yields the best compromise between stiffness and weight, minimizing a generalized penalty function that accounts for both the horizontal displacement of the tower top and its total mass. Modal analysis confirms that the chosen configuration maintains a natural frequency of 1.68 Hz, ensuring a safe margin from resonance. For the final analysis of the behavior of towers with elements of different cross-sectional shapes, finite element modeling was used for a detailed numerical study of their structural and performance characteristics. This allowed us to assess the impact of geometric constraints of structures and take into account the most unfavorable combinations of static and dynamic loads. The study yields a concise rule of thumb for towers with compact foundations, namely that the pyramidal-to-prismatic transition should be placed at roughly 78–80% of the total tower height. Full article

Blow flies (Diptera: Calliphoridae) play a crucial role in the decomposition process and serve as important forensic indicators due to their predictable colonization patterns. This review focuses on the dynamics of maggot masses, highlighting their ecological roles, thermoregulation, and implications for forensics. We summarize data on the self-organizing behavior of maggot masses, which is influenced by chemical cues and environmental factors. These masses can generate internal temperatures that exceed ambient levels by 10–20 °C, accelerating larval growth and impacting competition among individuals. This localized heating complicates the estimation of the postmortem interval (PMI), as traditional models may not take these thermal influences into account. Furthermore, maggot masses contribute significantly to nutrient cycling and soil enrichment, while the behavior of the larvae includes both cooperation and competition, which is influenced by the species composition present. This review highlights challenges in PMI estimation due to heat production but also discusses advancements in molecular tools and thermal modeling that enhance accuracy. Ultimately, we identify knowledge gaps regarding species diversity, microbial interactions, and environmental variability that impact mass dynamics, suggesting future research avenues that could enhance ecological understanding and forensic applications. Full article

Sports footwear is widely used across a range of physical activities. A key factor distinguishing running shoes from other types of footwear is the “drop,” the millimeter difference between the heel and the forefoot. This study aimed to analyze the influence of different drops (0, 5, and 10 mm) on ground reaction forces during walking and to examine the effects of sex and body mass index (BMI) under these conditions. An observational, descriptive, and cross-sectional study was conducted with 117 participants (56 men and 61 women). The Dinascan/IBV^® dynamometric platform (Instituto de Biomecánica de Valencia, Valencia, Spain) was used to measure ground reaction forces during walking (braking, take-off, propulsion, and swing forces), walking speed, and stance time. The descriptive analysis revealed comparable values for the left and right limbs, with slightly higher values observed in the right limb. Statistically significant differences were found in stance time, braking force, and swing force between the 0 mm and 10 mm drop conditions. Take-off force showed highly significant differences when comparing the 0–5 mm and 0–10 mm drop conditions. Sex-based differences were observed in all variables at the initial proposed drop condition of 0 mm, except for walking speed, possibly due to anatomical and physiological differences. Significant differences were found in stance time at 0 mm drop, braking force, and propulsion force. Highly significant values were obtained for take-off force and during the swing phase. A strong correlation was found between ground reaction forces and BMI with the different proposed drops in all forces studied, except for the support force, where a moderate correlation was obtained. Although shoe drop was found to influence ground reaction forces in this study, it is one of several factors that affect gait biomechanics. Other footwear characteristics, such as sole stiffness, material composition, weight, and elasticity, also play important roles in walking performance. Therefore, shoe drop should be considered an important but not exclusive parameter when selecting footwear. However, these results are limited to healthy young adults and may not be generalizable to other age groups or populations. Full article

Amphorae are a significant type of Roman pottery, serving as both transport containers and indicators of economic and technological practices across the Empire. Despite their importance in interpreting local economic dynamics in Roman Lusitania, the production origins, technological characteristics and functional roles of amphorae from Conímbriga in Portugal remain poorly understood. Previous research has focused primarily on typological comparisons with imported forms, providing limited insight into whether these vessels were produced locally or how they were incorporated into regional trade and agricultural systems. This study takes a multi-analytical approach to examine a group of ten amphorae dating from the 1st to the 5th century AD. While these vessels formally resemble well-known types from Gaul and Hispania, they appear to have been manufactured locally using fabrics consistent with those found in regional common wares. To examine the raw materials, production techniques and possible contents, the analysis integrates a typological assessment with a range of archaeometric methods, including optical microscopy (OM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Recent gas chromatography–mass spectrometry (GC–MS) results contextualise these data further, enabling an exploration of how specific technological choices may have influenced or reflected the intended function of the amphorae. The findings shed new light on local ceramic production and contributed to broader debates concerning Roman provincial economies and material culture. Full article

This article presents the results of a study on the possibility of using a single-speed multiphase model with free surface allowance for simulating boiling and condensation processes. The simulation is based on the VOF method, which allows the position of the interphase boundary to be tracked. To increase the stability of the iterative procedure for numerically solving volume fraction transfer equations using a finite volume discretization method on arbitrary unstructured grids, the basic VOF method is been modified by writing these equations in a semi-divergent form. The models of Tanasawa, Lee, and Rohsenow are considered models of interphase mass transfer, in which the evaporated or condensed mass linearly depends on the difference between the local temperature and the saturation temperature with accuracy in empirical parameters. This paper calibrates these empirical parameters for each mass transfer model. The results of our study of the influence of the values of the empirical parameters of models on the intensity of boiling and evaporation, as well as on the dynamics of the interphase boundary, are presented. This research is based on Stefan’s problem of the movement of the interphase boundary due to the evaporation of a liquid and the problem of condensation of vapor bubbles water columns. As a result of a series of numerical experiments, it is shown that the average error in the position of the interfacial boundary for the Tanasawa and Lee models does not exceed 3–6%. For the Rohsenow model, the result is somewhat worse, since the interfacial boundary moves faster than it should move according to calculations based on analytical formulas. To investigate the possibility of condensation modeling, the results of a numerical solution of the problem of an emerging condensing vapor bubble are considered. A numerical assessment of its position in space and the shape and dynamics of changes in its diameter over time is carried out using the VOF method, taking into account the free surface. It is shown herein that the Tanasawa model has the highest accuracy for modeling the condensation process using a VOF method taking into account the free surface, while the Rohsenow model is most unstable and prone to deformation of the bubble shape. At the same time, the dynamics of bubble ascent are modeled by all three models. The results obtained confirm the fundamental possibility of using a VOF method to simulate the processes of boiling and condensation and taking into account the dynamics of the free surface. At the same time, the problem of the studied models of phase transitions is revealed, which consists of the need for individual selection of optimal values of empirical parameters for each specific task. Full article

The communities that develop in prison are often small, insular, and central to the experience of incarceration. In these carceral communities, the deaths of individuals—especially those integral to these groups—can echo heavily within a housing unit, and even an entire institution, resulting in a collective experience of grief. While grief is experienced universally, it manifests in unique ways in the carceral context. The shared sorrow, loss, and sadness characterizing the experiences of those left behind are central to this form of mourning, and among imprisoned communities, grief is experienced uniquely. This paper draws on semi-structured interviews with 58 men imprisoned during the COVID-19 pandemic in an institution where over a dozen men died in a relatively short time. Their experiences suggest that, while grieving in prison is often complicated and may be repressed by both the individual and the carceral institution, bereavement may take a different form when experienced collectively and broadly within the carceral context. We develop the concept of mass carceral grief to explain this phenomenon. While unique in many ways, the lessons on carceral grief from this public health crisis can inform our broader understanding of how loss impacts those incarcerated. Full article

Objective: The high expression of prostate-specific membrane antigen (PSMA) associated with neovascularization in non-prostatic malignant tumors and metastatic lesions has been documented in many studies. By taking advantage of the absence of PSMA-related background activity in brain tissue, in recent years, PSMA has been used for the imaging of glial tumors, especially for postoperative follow-up. The aim of this prospective study was to investigate the diagnostic value of ⁶⁸Ga-PSMA-11 PET/CT by comparing ⁶⁸Ga-PSMA-11 PET/CT, ¹⁸F-FDG PET/CT, and MRI findings in patients with brain metastases (BM). Materials and Method: In this prospective study, 27 cases, 11 female and 16 male, with a mean age of 59.48 ± 12.21 years, were included. Patients diagnosed with BM on ¹⁸F-FDG PET/CT or CT/MRI at initial diagnosis or in the follow-up period were included in the study. PET findings of BM lesions obtained from ¹⁸F-FDG and ⁶⁸Ga-PSMA-11 PET/CT imaging, demographic characteristics, histopathological data of the primary foci, and other clinical features were evaluated together. Results: Twenty-four (89%) patients were included in the study for restaging, two (7%) patients for local recurrence assessment, and one (4%) patient for local recurrence and suspicion of additional lesions. The indications for ¹⁸F-FDG PET/CT were breast carcinoma for 37% (n:10), followed by lung carcinoma for 26% (n:7), colorectal adenocarcinoma for 14% (n:4), squamous cell larynx carcinoma for 7% (n:2), gastric signet ring cell carcinoma for 4% (n:1), pancreatic NET3 for 4% (n:1), thyroid papillary carcinoma for 4% (n:1), and malignant melanoma for 4% (n:1). In total, 26/27 included patients had PSMA-positive brain metastases but only one patient had PSMA-negative brain metastases with ⁶⁸Ga-PSMA-11 PET/CT imaging. This patient was followed with a diagnosis of primary larynx squamous carcinoma and had a mass suspected of brain metastases. Further tests and an MRI revealed that the lesion in this patient was a hemorrhagic metastasis. The smallest metastatic focus on ⁶⁸Ga-PSMA-11 PET/CT imaging was 0.22 cm, also confirmed by MRI (range: 0.22–2.81 cm). The mean ± SD SUVmax of the BM lesions was 17.9 ± 8.6 and 6.8 ± 5.2 on ¹⁸F-FDG PET/CT and ⁶⁸Ga-PSMA-11 PET/CT imaging, respectively. Metastatic foci that could not be detected by ¹⁸F-FDG PET/CT imaging were successfully detected with ⁶⁸Ga-PSMA-11 PET/CT imaging in 11 cases (42%). The distribution and number of metastatic lesions observed on cranial MRI and ⁶⁸Ga-PSMA-11 PET/CT were compatible with each other for all patients. Immunohistochemical staining was performed in the primary tumor of 10 (38%) cases, and positive IHC staining with PSMA was detected in 5 patients. In addition, positive IHC staining with PSMA was detected in all of the four surgically excised brain metastatic tumor foci. Conclusions: In this study,⁶⁸Ga-PSMA-11 PET/CT appears to be superior to ¹⁸F-FDG in detecting BM from various tumors, largely due to its high expression associated with neovascularization and the absence of PSMA expression in normal brain parenchyma. This lack of physiological uptake in healthy brain tissue provides excellent tumor-to-background contrast, further supporting the advantage of ⁶⁸Ga-PSMA-11 over ¹⁸F-FDG for BM imaging. However, larger studies are required to confirm these findings, particularly through comparisons across tumor types and histopathological subgroups, integrating PSMA immunohistochemistry (IHC) scores with ⁶⁸Ga-PSMA-11 uptake levels. Beyond its diagnostic potential, our results may also inform PSMA-targeted therapeutic strategies, offering new perspectives for the management of patients with brain metastases from diverse primary tumors. Full article

In the real world, forming a team of two or more people to solve a problem collaboratively is common to take advantage of the complementarity of the values and skills of team members. This idea can be used to develop more effective hybrid solution algorithms for solving problems by combining different solution strategies. In the realm of metaheuristic optimization, many hybrid metaheuristic algorithms have been developed based on combining different metaheuristic solution approaches. An interesting question is to study whether arbitrarily combining two different strategies can lead to a more effective solution approach to tackle complex problems. To evaluate whether a hybrid solution algorithm created by combining two different strategies to solve a problem is effective, we studied whether the hybrid solution algorithm can improve the performance and robustness by comparing the results of the solutions obtained by the hybrid solution algorithm with those obtained by the corresponding two original single-strategy solution algorithms. More specifically, we studied whether arbitrarily combining two different DE strategies selected from four standard DE strategies can lead to a more effective solution approach for planning sustainable Cyber–Physical Production Systems (CPPSs) modeled with multi-agent systems (MASs) in terms of performance and robustness. Ten cases for testing the algorithms for planning sustainable processes in CPPSs, with up to 20 operations and up to 40 resources, were used in the experiments. We conducted experiments by applying 13 algorithms, including 6 hybrid DE algorithms and 7 existing algorithms (4 standard DE, NSDE algorithms, PSO, SaNADE), to find the solutions for 10 discrete optimization planning problems with various types of constraints. The results of the experiments show that each self-adaptive hybrid DE algorithm either outperforms or performs as well as the four standard DE algorithms, NSDE algorithm, and PSO algorithm in most test cases in terms of performance and robustness for population sizes of 30 and 50. The rankings generated through the Friedman test based on the results of the experiments also show that the rankings of the six hybrid DE algorithms created based on hybridization are better than most of the others seven existing algorithms, with only one exception. The rankings generated via the Friedman test indicate that the top 3 among the 13 algorithms are the hybrid DE algorithms. The results of this study provide a simple rule to develop a more effective hybrid DE algorithm by combining two DE strategies. Full article

Wood density is a key property since it affects almost every other property of wood such as its elasto-mechanical, acoustic, thermal, or electrical properties. Hence, it is essential to determine wood density for the interpretation of any other property test. Density measurements are usually carried out gravimetrically by measuring the wood specimens’ dimensions and taking their weight. In order to be independent of moisture, wood density is measured at an absolute dry state. However, depending on which wood properties shall be measured after the oven-dry density is determined, heating the wood up to 103 °C can be problematic because the volatile components of the wood can evaporate. For this reason, the drying conditions (temperature in °C (60, 80, 103 °C)), duration in h (8, 16, 24, 48 h)) required to achieve an absolute dry state inside wood specimens—being obligatory for the analysis of various physical, mechanical, or even biological properties—were examined for different softwood and hardwood species. Basically, oven-dry measurements (i.e., 48 h at 103 °C) themselves contained a significant error, which was considered to be the result of deviations in the handling of the specimens and the scales used. Using temperatures below 103 °C was critical for the determination of absolute dry mass and dimensions. Wood specimens with a high content of volatile ingredients led to an apparently increased residual MC (e.g., shown for Scots pine heartwood), thus volatile ingredients were considered an additional source of error during oven-dry measurements. Full article

Background/Objectives: Gut microbiota is profoundly influenced by dysglycemic states, including prediabetes (preDM) and type 2 diabetes (T2D). Although short-chain fatty acids (SCFAs) may serve as proxies reflecting these microbial changes, their predictive role remains elusive. This study aimed to evaluate the association between fecal SCFA concentrations and glycemic status (preDM and T2D), using individuals with normoglycemia (NonDM) as the reference group in a Mediterranean adult population. Methods: This study included a total of 88 participants from the Di@bet.es study who were classified into three groups according to the American Diabetes Association criteria: NonDM (45%), preDM (27%), and T2D (28%), respectively. We evaluated gut microbiota populations through massive sequencing and determined SCFAs concentration using gas chromatography–mass spectrometry. Adjusted multiple logistic regression models were used to estimate associations between SCFAs and metabolic status. Results: The mean age of subjects with preDM and T2D was approximately 68 years, older than that of NonDM participants (about 60 years). About 50% of the subjects in the NonDM and preDM groups were female, whereas in the T2D group, females represented about 25%. The analysis revealed that only fecal acetic acid was significantly reduced in T2D compared to NonDM (p = 0.036) and preDM (p = 0.018) groups. Remarkably, fecal acetic acid was negatively associated with T2D risk when taking preDM as the reference state (OR = 0.561 [95% CI: 0.371–0.846], p = 0.009). Intriguingly, fecal acetic acid was identified as a significant positive predictor of preDM risk, taking the NonDM group as reference (OR = 1.422; p = 0.028), while propionic acid was inversely associated with preDM (OR = 0.714; p = 0.028). Conclusions: Our analysis showed that fecal acetic acid levels were associated with a reduced risk of T2D but also with an increased risk of preDM; however, the biological relevance of these findings remains uncertain. Full article

Soil treatment is one of the most energy-intensive agricultural processes. While power take-off (PTO)-powered rotary tillage tools are widely used due to their operational advantages, their energy efficiency requires enhancement. A new PTO-powered rotary tillage tool was designed, with cutting blades inclined at angle β to prevent soil mass accumulation due to soil sliding along the blades, thereby enhancing energy efficiency and tillage quality. A kinematic model was developed to analyze the tool’s motion trajectories. Theoretical analysis substantiated the optimal inclination angle β = 38–42° and elliptical-profile edge configuration of the cutting blades. During field experiments for performance evaluation, the angle of attack was in the range 20° < α < 40°, and the kinematic coefficient varied in the range 1.0 < η < 1.21 in 0.07 increments. Results demonstrated that draught force and torque reduced by 1.3–1.5 and 1.1–1.4 times, respectively, with an increasing kinematic coefficient. Minimal specific total power requirements of 4.5–4.7 kW/m were obtained at the optimal kinematic coefficient, η = 1.14–1.21, and angle of attack, α = 40°. Compared to base ring tillage discs, the new design reduces total power requirements by 14–16%. Furthermore, it provides required tillage quality: soil pulverization ≥ 80%, weed cutting ≥ 97%, crop residue retention ≥ 60%, and roughness of the field soil surface ≤ 3 cm. Full article

Background/Objectives: Organized physical activity is frequently considered a protective factor against bullying behaviors, yet evidence within the university context remains limited. This study investigates the relationships between physical activity levels, body mass index (BMI), and involvement in traditional and digital bullying, taking into account the differences between students with and without structured sports training. Methods: A total of 2767 first-year students from Transylvania University of Brașov participated. The sports group (n = 161; 65 females, 96 males) was compared to the non-sports group (n = 2606; 1472 females, 1134 males). Instruments included the Physical Activity Questionnaire for Adolescents (PAQ-A), validated scales for traditional and cyberbullying and victimization, and BMI calculation. Statistical analyses involved t-tests (two-tailed), 2 × 2 factorial ANOVA, and sex-stratified multiple linear regressions. Results: Students with sports training reported higher physical activity (PAQ-A 4.2–4.6), lower BMI, and lower bullying involvement (traditional ≈ 14–21% vs. ≈32%; cyber ≈ 8–17% vs. ≈25%). Group differences were large for physical activity (Hedges’ g ≈ 1.5) and moderate for BMI and bullying (g ≈ 0.68–0.96; point-biserial r² ≈ 3–4%). ANOVA showed sports status main effects (partial η_p² ≈ 4–5% for bullying/BMI; ≈20% for PAQ-A). In regressions, sports status (B = −0.30 to −0.44) and physical activity (B = −0.22 to −0.32) predicted lower aggression/victimization, whereas BMI showed positive associations (B = 0.11 to 0.18) (all p < 0.001). Sex × sports interactions were significant for PAQ-A and for traditional and cyber-victimization. Conclusions: Structured physical activity contributes to reducing the risk of bullying involvement and supports better psychosocial adjustment among students. These findings underscore the educational and preventive potential of university sports programs. Full article