Search Results (246)

Channels with three standard symmetrical sections and one asymmetric section are mounted as cantilever beams with the web oriented vertically. A classical solution to the analysis of stress in each thin-walled cantilever channel is provided using the principle of wall shear flow superposition. The latter is coupled with a further superposition between axial stress arising from bending and from the constraint placed on free warping imposed at the fixed end. Closed solutions for design are tabulated for the net shear stress and the net axial stress at points around any section within the length. Stress distributions thus derived serve as a benchmark structure for alternative numerical solutions and for experimental investigations. The conversion of the transverse free end-loading applied to a thin-walled cantilever channel into the shear and axial stress that it must bear is outlined. It is shown that the point at which this loading is applied within the cross-section is crucial to this stress conversion. When a single force is applied to an arbitrary point at the free-end section, three loading effects arise generally: bending, flexural shear and torsion. The analysis of each effect requires that this force’s components are resolved to align with the section’s principal axes. These forces are then considered in reference to its centroid and to its shear centre. This shows that axial stress arises directly from bending and from the constraint imposed on free warping at the fixed end. Shear stress arises from flexural shear and also from torsion with a load offset from the shear centre. When the three actions are combined, the net stresses of each action are considered within the ability of the structure to resist collapse from plasticity and buckling. The novelty herein refers to the presentation of the shear flow calculations within a thin wall as they arise from an end load offset from the shear centre. It is shown how the principle of superposition can be applied to individual shear flow and axial stress distributions arising from flexural bending, shear and torsion. Therein, the new concept of a ‘trans-moment’ appears from the transfer in moments from their axes through centroid G to parallel axes through shear centre E. The trans-moment complements the static equilibrium condition, in which a shift in transverse force components from G to E is accompanied by torsion and bending about the flexural axis through E. Full article

The making of a land patrimony for the benefit of religious missions is profoundly linked to territorial construction in the colonies but is rarely examined from the angle of ecclesiastical governmentality over the ceded lands. This analysis highlights three complementary processes for understanding the role of religious mission land heritage in territorial reconfigurations. First, this article examines the process of “land sanctuarization”, which materializes territorial anchoring through the crystallization of land rights granted to religious missions over customary lands previously presumed to be “vacant”. Next, it explores the formation of an “ecclesiastical dominium”, manifested in the dismantling of state missions and their free transfer, explicit or tacit, to religious missions under concession or agreement regimes. This reveals the exercise of state power over the land heritage of religious missions, positioning them as structuring axes and administrative intermediaries for public services, thus giving rise to an ecclesiastical governmentality that drives territorial production and reconfiguration. Finally, postcolonial dynamics reveal the resurgence of new spatial polarities shaped by the complexity of evolving religious actors along the center–periphery axis of a recomposing territorialization. This study underscores the importance of a transversal approach to better govern the land legacies of religious missions, fostering a pluralistic reterritorialization of postcolonial societies in central Africa. Full article

Background: We evaluated the utility of HNSCC LN R2* relaxation times to infer the oxygenation status of LN non-invasively at baseline and when breathing air and 100% oxygen to predict chemoradiotherapeutic locoregional response at 2 years. Hypoxia within LNs has been associated with poorer outcomes following CRT. Deoxyhaemoglobin decreases MRI transverse relaxation time (T2*) (lengthening inverse, R2*). Methods: A total of 54 patients underwent 1.5T-MRI before CRT. Conventional MR sequences were supplemented with T2* sequences breathing both air and 100% oxygen; pathological nodes identified in consensus were volumetrically contoured to T2* parametric maps. Results: Patients followed-up with for >2 years were categorised by multidisciplinary consensus into post-therapy complete local response (CR; n = 32/54) and local nodal disease relapse (RD; n = 22/54). Our data demonstrated, by R2*, that nodes that sustained post-therapy CR are significantly more hypoxic compared with relapsing nodes and paradoxically demonstrate a significant increase in hypoxia on 100% oxygen. Pre-treatment LN short axis diameter, various qualitative descriptors of malignancy, and quantitative DWI were not useful in discriminating successful response to CRT. Conclusions: This study demonstrates that a significant differential response to 100% oxygen and higher baseline R2* LN measurements could be exploited in risk stratification prior to CRT, and future work could be directed towards understanding the contrast mechanisms of R2* imaging, underpinning the observed differences in the context of hypoxia. Full article

Web-tapered beams with I-sections, which are aesthetic and structurally efficient, have been widely used in steel structures. Web-tapered I-section beams bent about the strong axis may undergo out-of-plane buckling through lateral deflection and twisting. This primary stability failure mode in slender beams is known as lateral-torsional buckling (LTB). Unlike prismatic I-beams, the complex mode shape of web-tapered I-section beams makes it challenging or even impossible to derive a closed-form expression for the LTB load under certain transverse loading conditions. Therefore, the LTB assessment of web-tapered I-section beams is primarily performed using finite element analysis (FEA). However, this method involves multiple steps, requires specialized expertise, and demands significant computational resources, making it impractical in certain cases. This study proposes an analytical approach based on the Ritz method to evaluate the LTB of simply supported web-tapered beams with doubly or mono-symmetric I-sections. The proposed analytical method accounts for web tapering, I-section mono-symmetry, types and positions of transverse loads, and beam slenderness. The method was implemented in Mathematica to allow the rapid evaluation of the LTB capacity of web-tapered I-beams. The study validates the LTB loads computed using the developed Mathematica package against results from shell-based FEA. An excellent agreement was observed between the analytically and numerically calculated LTB loads. Full article

Background/Objectives: One of the surgical interventions applied in the cervical region is the pedicle screw method. The cervical pedicle screw is stronger than any other screw method; however, use of the cervical pedicle screw is limited due to the variability in the anatomy of the cervical vertebrae and the risks to the neurological and vascular structures in this region. This study aimed to determine the morphological features of subaxial cervical vertebrae of the adult Turkish population and to provide guidance for the pedicle screwing method. Methods: In our study, pedicle analyses were examined in the subaxial neck vertebrae of a total of 60 patients, 30 male and 30 female, using computed tomography images. In subaxial vertebrae (C3–C7), bilateral pedicle width, pedicle axis length, pedicle transverse angle, sagittal and transverse diameter of vertebral foramen, and the distance between two pedicles were measured. Results: Pedicle widths that did not fit the commonly used 3.5 mm pedicle screw were detected in both male and female patients. The mean bilateral pedicle width in male patients was found to be greater than in female patients. When the parameter results were compared according to the levels, it was found that the pedicle width, pedicle axis length, transverse diameter, and the distance between the two pedicles increased statistically significantly. Conclusions: We think that the data obtained from the study will help determine the appropriate screwing (screw selection) in subaxial vertebra pedicle surgery and increase the success of the surgical procedure. Full article

We investigate a two-dimensional system of active Brownian dumbbells using molecular dynamics simulations. In this model, each dumbbell is driven by an active force oriented perpendicular to the axis connecting its two constituent beads. We characterize the resulting phase behavior and find that, across all values of activity, the system undergoes phase separation between dilute and dense phases. The dense phase exhibits hexatic order, and for large enough activity, we observe a marked increase in local polarization, with dumbbells predominantly oriented towards the interior of the clusters. Compared to the case of axially self-propelled dumbbells, we find that the binodal region is enlarged towards lower densities at all activities. This shift arises because dumbbells with transverse propulsion can more easily form stable cluster cores, serving as nucleation seeds, and show a highly suppressed escaping rate from the cluster boundary. Finally, we observe that clusters exhibit spontaneous rotation, with the modulus of the angular velocity scaling as $\omega \sim r_g^{-2}$, where $r_g$ is the cluster’s radius of gyration. This contrasts with axially propelled dumbbells, where the scaling follows $\omega \sim r_g^{-1}$. We develop a simplified analytical model to rationalize this scaling behavior. Full article

This paper presents the results of experimental studies on the propagation of longitudinal and transverse ultrasonic waves through a metamaterial—a composite material based on polymer matrix with periodically arranged cylindrical elements. Such structures are known as phononic crystals. Amplitude–frequency characteristics were measured for phononic crystals with air and metal cylindrical elements, for both longitudinal waves (in the frequency range from 1.5 to 3 MHz) and transverse waves (in the range from 0.2 to 1.2 MHz). A twofold decrease in the amplitude of the transmitted longitudinal ultrasonic wave was experimentally demonstrated in the passband centered at 1.87 MHz during rotation of the phononic crystal. It was also found that the polarization angle of the transverse ultrasonic wave influences the localization of band gaps and passbands. Band gaps, characterized by amplitude minima near 240 kHz, 290 kHz, and 830 kHz and observed for waves polarized parallel to the crystal axis, are replaced by passbands when the wave is polarized perpendicularly. These results suggest the potential for developing analog ultrasonic frequency filters tunable by the angle of rotation. Full article

Evaluating the properties of single carbon fibers is crucial, as it provides parameters not only for optimizing carbon fiber production processes but also for enhancing composite material properties. In recent years, significant advancement have been made in the evaluations of the transverse compressive properties of single fibers. However, compressive testing methods for fibers in the fine size range remain limited at the commercial scale. The direct measurement of the transverse compressive properties of three domestic high-strength polyacrylonitrile-based single carbon fibers (T300 grade, T700 grade, and T800 grade) with diameters of ~5.5~6.5 μm was made possible through the use of a micro-compression tester. Transverse compressive moduli of 5.19 GPa (0.050), 5.42 GPa (0.104), and 6.63 GPa (0.120) were obtained for domestic T300-, T700- and T800-grade carbon fibers, respectively. In addition, transverse compressive strengths of 2.35 GPa (0.033), 2.65 GPa (0.041), and 2.82 GPa (0.121) were obtained for domestic T300-, T700- and T800-grade carbon fibers, respectively. It is noted that minor deviations in fiber geometry from an ideal circular cross-section may influence absolute modulus and strength values. These fibers exhibit strong anisotropy in the longitudinal and transverse directions from the fiber axis. A correlation between the transverse compressive modulus and strength was found for these fibers. These results provide critical parameters for the optimization of carbon fiber-reinforced composite designs (e.g., enhancing impact resistance in aerospace structures), offering substantial practical value to the field of materials science. Full article

Background: Mid-shaft clavicle fracture fixation carries neurovascular injury risk. The purpose of this study was to compare bicortical compression and unicortical locked clavicle plate constructs biomechanically. Materials and Methods: Ten fourth-generation composite transverse mid-shaft clavicle osteotomy specimens were assigned to two groups, and each clavicle was fixed with an eight-hole second-generation 3.5 mm pelvic reconstruction plate placed superiorly. Group one included five fixed with bicortical compression screws and group two included five fixed with unicortical locking screws. All were tested on a four-axis servohydraulic testing frame in three modes: axial rotation, anterior/posterior bending, and cephalad/caudad bending. Results: Mean construct stiffness for AP bending was 1.255 ± 0.058 Nm/deg (group 1) and 1.442 ± 0.065 Nm/deg (group 2) (p = 0.001). Mean construct stiffness for axial rotation was 0.701 ± 0.08 Nm/deg (1) and 0.726 ± 0.03 Nm/deg (2) (p = 0.581). Mean construct stiffness for cephalad bending was 0.889 ± 0.064 Nm/deg (1) and 0.880 ± 0.044 Nm/deg (2) (p = 0.807). Mean construct stiffness for caudal bending was 2.523 ± 0.29 Nm/deg (1) and 2.774 ± 0.25 Nm/deg (2) (p = 0.182). Conclusions: With transverse mid-shaft clavicle fractures, unicortical locking fixation provided comparable rigidity to bicortical compression fixation in axial rotation, cephalad bending, and caudal bending; it provided greater rigidity in AP bending. Full article

During the continuous casting process, the submerged entry nozzle (SEN) should be maintained at the geometric center of the mold. However, in actual production, factors such as deformation of the tundish bottom and inaccurate positioning of the traversing car occasionally cause SEN offset. SEN offset can make the molten steel flow field in the mold asymmetric, increasing the risks of slag entrainment on the surface of the casting blank and breakout accidents. To evaluate the influence of different SEN offsets on the mold flow field, this study uses a slab continuous casting mold with a cross-section of 920 mm × 200 mm from a specific factory as the research object. Mathematical simulations were used to investigate the influence of SEN offsets (including width-direction and thickness-direction offsets) on the flow behavior of molten steel in the mold. A physical water model at a 1:1 scale was established for verification. Two parameters, the symmetry index (S) and the bias flow index (N), were introduced to quantitatively evaluate the symmetry of the flow field, and the rationality of the liquid-level fluctuation under this flow field was verified using the F-number (proposed by Japanese experts for mold level fluctuation control) from the index model. The results show the following: when the SEN offset in the thickness direction increases from 0 to 50 mm, the longitudinal symmetry index (Sy) of the molten steel flow field in the mold decreases from 0.969 to 0.704—a reduction of 27.4%; the longitudinal bias flow index (Ny) of molten steel level fluctuation increases from 0.007 to 0.186, representing a 25.6-fold increase, and the F-number rises from 4.297 to 8.482; when the SEN offset in the width direction increases from 0 to 20 mm, the transverse-axis symmetry index (Sx) of the flow field decreases gradually from 0.969 to 0.753 at a 20 mm offset, which is a reduction of approximately 22.29%; the transverse-axis bias flow index (Nx) increases from 0.015 to 0.174 at a 20 mm offset—an increase of 10.6 times; and the F-number increases from 4.297 to 5.548. Considering the comprehensive evaluation of horizontal/vertical symmetry indices, bias flow indices, and F-numbers under the two working conditions, the width-direction SEN offset has the most significant impact on the symmetry of the molten steel flow field. Full article

A novel parameter optimization method for additively manufacturing nickel–titanium (NiTi) alloys using laser powder bed fusion (LBPF) was developed. Compared with the conventional NiTi alloy and the previously reported LPBF-NiTi alloy, the LBPF-NiTi alloy prepared with these parameters exhibits excellent tensile properties and an anisotropic microstructure. Since distinct regions of orthopedic implants have specific functional requirements, we investigated the anisotropy of this LPBF-NiTi in terms of its osteoinductive capacity to determine the appropriate building direction for prosthesis fabrication. The biosafety of the transverse (XY-NiTi) and longitudinal (XZ-NiTi) planes was assessed through cytotoxicity assays. Comparative analyses of the biological activities of these planes were conducted by evaluating the adherent cell counts, the adhesion morphology, and the expression of osteogenic-related genes and factors in adherent cells. Compared with XZ-NiTi, XY-NiTi exhibited superior cell adhesion properties. Additionally, the expression levels of osteogenic markers (RUNX2, ALP, OPG, and OCN) were significantly greater in bone marrow mesenchymal cells (BMMCs) adhered to XY-NiTi than in those adhered to XZ-NiTi. These results indicate a greater osteogenic potential in the XY-NiTi group. XY-NiTi was more advantageous as an implant–bone contact surface. Building implant products in the direction perpendicular to the load-bearing axis enhances biofixation; thus, this is the preferred orientation for manufacturing orthopedic implants. Full article

Historical mosques are some of the most valuable structures in Islamic societies. It is of primary importance to protect these structures and ensure their safe transmission to future generations. This study investigates the adequacy of the buttress system of the Süleymaniye Mosque in Istanbul, regarded as the ‘symbol structure of Ottoman Architecture’, against gravity and horizontal earthquake loads. Although several structural studies have been conducted on this unique building, the absence of any research on the buttress system, which clearly plays a significant role in its survival through many earthquakes, served as the main motivation for this study. After presenting the material properties, a finite element model of the structure was created. Finite element models were also developed for two hypothetical scenarios in which the outer depths of the buttresses were reduced by fifty percent or eliminated. The models and all analyses were performed using ABAQUS software. Gravity load analyses indicated that the mosque does not face any issues related to stresses or displacements. Nonlinear static analyses revealed that, with the current buttress dimensions, the structure can resist horizontal loads up to about 70% of self-weight along the Qibla axis and about 90% along the axis perpendicular to the Qibla. These findings are some of the most significant results obtained thus far in studies investigating the horizontal earthquake resistance of the mosque. Through performance analyses, it was determined that the structure can meet the limited damage performance criterion only with the current buttress depths; however, it cannot satisfy this performance level with reduced buttress dimensions. In conclusion, the study demonstrated that the buttress system of the Süleymaniye Mosque is highly effective against gravity loads and transverse seismic forces and that it was designed not only with practical experience but also with a solid understanding of structural behavior. Full article

Background: Malnutrition is a prevalent condition associated with adverse health outcomes, requiring the accurate assessment of muscle composition and fat distribution. Methods: This study presents a novel method for the automatic analysis of ultrasound images to estimate subcutaneous and visceral fat, as well as muscle, in patients with suspected malnutrition. The proposed system utilizes computer vision techniques to segment regions of interest (ROIs), calculate relevant variables, and store data for clinical evaluation. Unlike traditional segmentation methods that rely solely on thresholding or pre-defined masks, our method employs an iterative hierarchical approach to refine contour detection and improve localization accuracy. A dataset of abdominal and leg ultrasound images, captured in both longitudinal and transversal planes, was analyzed. Results: Results showed higher precision for longitudinal scans compared to transversal scans, particularly for length-related variables, with the Y-axis Vastus intermediate achieving a precision of 92.87%. However, area-based measurements demonstrated lower precision due to differences between manual adjustments by experts and automatic geometric approximations. Conclusions: These findings highlight the system’s potential for clinical use while emphasizing the need for further algorithmic refinements to improve precision in area calculations. Full article

Accumulative roll bonding was employed on 1060 aluminum alloy along the transverse direction without lubrication. The texture evolution and lattice rotation of an ARB-processed aluminum sheet, which initially exhibited a rotated β fiber texture, were examined using X-ray diffraction. Successful interlayer bonding was achieved during the ARB process, and the grains in the sheets were refined and stretched along the rolling direction. The rotated β fiber was unstable during shear deformation, gradually transitioning to a stable r-cube orientation along different rotation paths. Variations in ODFs with accumulated true strain were utilized to determine the rotation paths from the initial rotated β fiber to the end r-cube orientation. The rotated β fiber disappearance rate initially decreased rapidly as the accumulated true strain increased, followed by a slower decline. The B’ {0 1 1}<1 1 1> orientation moved to the S’ {1 2 3}<17 22 9> orientation along the skeleton of the initial rotated β fiber, while the C’ {1 1 2}<1 1 0> orientation moved to the r-cube orientation along the transverse direction axis. A slight deviation from the C’ orientation was revealed in the rotation path from the S’ orientation to the r-cube orientation. Texture evolution was clarified quantitatively through establishing a mathematical relation between texture component volume fractions and accumulated true strain utilizing the JMAK equation. The relatively high r values indicated that the JMAK equation could quantify texture evolution during shear deformation. Full article

This study aimed to assess the beaks of Neotropical birds using two scanning techniques—CT and a dental intraoral scanner—along with macroscopic analysis. Six specimens per family were selected, including parakeets, red-legged seriemas, and black vultures. The upper beaks were measured in the CT sagittal view for length along the longitudinal axis and height on the transverse axis. The same measurements were performed on the 3D images. Additionally, beak width in the middle of the naris area, as well as the length and height of the nares, were measured on the 3D images. The closed polygon tool outlined the beak, generating volume in cm². The 3D images obtained with the dental scanner were measured, similarly to those from 3D-CT scans for the beaks’ length, height, and width. Macroscopic measurements of the beaks were also conducted. Some differences in beak measurements between imaging methods were verified. In conclusion, both techniques are effective, but CT provides more detailed information. The combination of both methods would be ideal for developing and applying beak prostheses. Full article