Search Results (83)

With the extensive application of 3D-printed composites across multiple industries, the investigation into their structural reliability under complex loading conditions has become a critical research focus. This study comprehensively employs acoustic emission (AE) monitoring, digital image correlation (DIC) measurement, and micro-computed tomography (Micro-CT) visualization techniques to explore the progressive damage behavior of 3D-printed sandwich-structured composites reinforced with continuous carbon fiber sheets under three-point bending. Mechanical tests show that increasing the fiber content of face sheets from 10% to 20% enhances average bending strength by 56%, while low fiber content compromises stiffness and load-bearing capacity. AE analysis categorizes damage modes into matrix cracking (<50 kHz), debonding/delamination (50–150 kHz), and fiber breakage (>150 kHz) using k-means clustering algorithms. DIC measurement reveals significant structural deformation processes during damage progression. The AE-DIC-Micro-CT combination demonstrates an initial undamaged state, followed by damage initiation and propagation in the subsequent stages. This integrated approach provides an effective method for damage assessment, guiding the design and reliability improvement of 3D-printed composites. Full article

The increasing demand for accurate and accessible medical imaging has driven efforts to develop technologies that overcome limitations associated with conventional imaging techniques, such as MRI and CT scans. This study presents the design and implementation of an electronic interface for acquiring signals from a piezoelectric ultrasound sensor with the aim of improving image reconstruction quality by addressing electromagnetic interference and speckle noise, two major factors that degrade image fidelity. The proposed interface is installed between the ultrasound transducer and acquisition system, allowing real-time signal capture without altering the medical equipment’s operation. Using a printed circuit board with 110-pin connectors, signals from individual piezoelectric elements were analyzed using an oscilloscope. Results show that noise amplitudes occasionally exceed those of the acoustic echoes, potentially compromising image quality. By enabling direct observation of these signals, the interface facilitates the future development of analog filtering solutions to mitigate high-frequency noise before digital processing. This approach reduces reliance on computationally expensive digital filtering, offering a low-cost, real-time alternative. The findings underscore the potential of the interface to enhance diagnostic accuracy and support further innovation in medical imaging technologies. Full article

Progressive damage evolution in rock masses serves as the fundamental mechanism driving geological hazards by controlling deformation patterns and failure predictability. To address the critical challenge of predicting fracture behaviors in heterogeneous geological media, this study pioneers the integration of real-time computed tomography (CT) scanning and acoustic emission (AE) monitoring to investigate self-organized criticality and fracture predictability in Cretaceous sandstone under uniaxial compression. By systematically analyzing internal structural evolution and damage parameters, this established a multiparameter framework to characterize self-organized processes and critical phase transitions during progressive fracturing. Key findings include the following: (1) Distinct critical thresholds emerge during yield-stage self-organization, marked by abrupt transitions in AE signals and crack metrics—from microdamage coalescence initiating volumetric expansion (first critical point) to macrocrack nucleation preceding peak strength (second critical point). (2) AE-crack evolution follows power–law statistics, where elevated scaling exponents (r > 0.85) correlate with intensified nonlinear damage, accelerated localization, and progressive rate enhancement. Yield-stage power–law acceleration provides quantifiable failure precursors. (3) Yield-stage damage patterns exhibit 85% similarity with terminal failure configurations, confirming yield-stage as the definitive precursor with critical temporal signatures for failure prediction. A conceptual framework integrating multiparameter responses (AE signals, crack metrics) was developed to decipher self-organized critical phase transitions during deformation-failure processes. This work establishes methodological foundations for investigating damage mechanisms and predictive strategies in heterogeneous rock systems. Full article

Background: The lateral angle of the internal acoustic meatus of the petrous bone is a sexually dimorphic feature used for sex determination, particularly in fragmented or cremated remains. However, studies show conflicting results regarding its accuracy, and the reasons for its dimorphism remain unclear. The aim of this study is to analyze sexual dimorphism in subadult individuals and to examine the association of the lateral angle with cranial breadth as an explanation for its sexual dimorphism, as well as interpopulation differences. Methods: We measured the lateral angle and biauricular breadth in 204 individuals (birth to 30 years) using CT scans from Austrian 19th-century anatomical collections and data from the New Mexico Decedent Image Database. Results: This study revealed that the sexual dimorphism of the lateral angle and cranial dimensions manifests during puberty, along with a strong association between the lateral angle and the biauricular breadth. Additionally, this study noted interpopulation variability in cranial breadth, with different levels of sexual dimorphism observed across diverse populations. Conclusions: The findings offer a potential explanation for the observed variability in lateral angle measurements across studies and the limitations of universal cut-off points as a sex-determination method in osteology. Full article

This study reveals the damage mechanisms and fracture evolution characteristics of deeply buried granite with prefabricated joints (inclinations of 0°, 30°, 45°, 60°, and 90°) using uniaxial compression tests monitored by Acoustic Emission (AE) technology. Three-dimensional X-CT technology was used to analyze post-damage fracture evolution in specimens with varying joint inclinations. The results show that the stress–strain curve of deeply buried jointed granite under uniaxial compression includes three stages: initial compaction, crack extension, and failure. AE characteristics align with these stages, showing clear stress responses and timing features. In the initial compaction stage, micro-crack closure dominates, with smaller joint inclinations showing stronger closure effects. In the crack extension stage, joint inclination determines the crack propagation mode. In the failure stage, joint inclination significantly affects the spatial distribution of the rupture network by altering stress concentration areas and crack types. The proportion of shear micro-cracks increases with joint inclination, and peak strength rises with increasing joint angle, potentially accelerating micro-crack evolution. These findings provide valuable insights for designing excavation and instability monitoring in deeply buried multi-jointed granite underground projects. Full article

This review focuses on the contribution of medical imaging in the diagnosis of peripheral vestibular disorders. This is a narrative review based on a focused literature search conducted using PubMed and the Cochrane Library. Imaging is not usually recommended in initial consultations for vestibular disorders because only 5–10% of MRI scans reveal findings directly related to the disease. The study is a review of the literature that highlights the utility and limitations of imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). It follows the diagnostic approach from history and physical examination to laboratory tests and imaging. Some conditions like vestibular neuritis and benign paroxysmal positional vertigo (BPPV) have limited imaging utility due to the fine details required. Conversely, high-resolution CT and MRI are important for diagnosing Meniere’s disease, acoustic neuroma, and superior canal dehiscence. The role of imaging varies a lot among specific conditions. Advances in imaging technology, particularly high-resolution MRI, promise enhanced diagnostic capabilities. Full article

A model of the vocal tract that mimicked velopharyngeal insufficiency was created, and acoustic analysis was performed using the boundary element method to clarify the acoustic characteristics of velopharyngeal insufficiency. The participants were six healthy adults. Computed tomography (CT) images were taken from the frontal sinus to the glottis during phonation of the Japanese vowels /i/ and /u/, and models of the vocal tracts were created from the CT data. To recreate velopharyngeal insufficiency, coupling of the nasopharynx was carried out in vocal tract models with no nasopharyngeal coupling, and the coupling site was enlarged in models with nasopharyngeal coupling. The vocal tract models were extended virtually for 12 cm in a cylindrical shape to represent the region from the lower part of the glottis to the tracheal bifurcation. The Kirchhoff–Helmholtz integral equation was used for the wave equation, and the boundary element method was used for discretization. Frequency response curves from 1 to 3000 Hz were calculated by applying the boundary element method. The curves showed the appearance of a pole–zero pair around 500 Hz, increased intensity around 250 Hz, decreased intensity around 500 Hz, decreased intensities of the first and second formants (F1 and F2), and a lower frequency of F2. Of these findings, increased intensity around 250 Hz, decreased intensity around 500 Hz, decreased intensities of F1 and F2, and lower frequency of F2 agree with the previously reported acoustic characteristics of hypernasality. Full article

This study presents a comparative analysis of the computed tomographic (CT), radiographic, and ultrasonographic (US) characteristics of gastrointestinal foreign bodies, including bezoars, in dogs and cats, and evaluates their association with complications and clinical outcomes. A total of 33 cases (26 dogs, 7 cats) with surgically or endoscopically confirmed foreign bodies were reviewed, classified as bezoars (n = 15) or distinct foreign bodies (n = 18). CT features such as attenuation values, transition zones, and proximal-to-distal small intestinal diameter ratios were compared. Bezoars typically appeared as intraluminal masses with mottled gas patterns and indistinct boundaries (33.3% vs. 94.4%, p < 0.001) and were associated with longer clinical signs (median 14 vs. 5.5 days, p = 0.013), more frequent transition zones (92.3% vs. 41.7%, p = 0.011), and a greater diameter ratio (2.9 vs. 1.25, p = 0.012) across the transition zone. Radiographic and US evaluations were available in six bezoar cases; only one radiograph (17%) detected the bezoar, while US showed acoustic shadowing in four cases (67%). Six patients (18%) experienced adverse outcomes, with bowel wall ruptures significantly associated with poor prognosis (p < 0.001). These findings highlight the superior diagnostic performance of CT, particularly for bezoars, and emphasize the importance of identifying transition zones and bowel diameter ratios in assessing gastrointestinal foreign bodies and their associated risks. Early CT evaluation may thus facilitate timely intervention and improve clinical outcomes. Full article

Hydraulic fracturing can significantly enhance coalbed methane production, with in-situ stress playing a crucial role in this process. Our study focuses on calculating in-situ stress in the deep 8+9# coal seam in the north-central Zijinshan block. Leveraging data from acoustic logging and hydraulic fracturing tests, we developed a stress prediction model tailored to the area’s geology. We analyzed stress’s impact on fracturing behavior and the origins of mechanical anisotropy in deep coal reservoirs using μ-CT imaging. Our results show that the Anderson-modified model, accounting for transverse isotropy, offers greater accuracy and applicability than traditional models. The study area exhibits a normal faulting stress regime with significant stress contrasts and maximum horizontal principal stress aligned with the east-west geological stress direction. After hydraulic fracturing, fractures form a complex fracture system resembling elongated ellipses in the coal reservoir, primarily extending in the vertical direction. To control fracture height and prevent penetration through the roof and floor, regulatory measures are essential. μ-CT analysis revealed the distribution of primary fractures, pores, and minerals in the coal, contributing to mechanical anisotropy. This research advances CBM development in the Zijinshan block and similar regions by refining stress prediction and fracturing propagation methods. Full article

Mastoidectomy is critical in acoustic neuroma surgery, where precise planning of the bone milling area is essential for surgical navigation. The complexity of representing the irregular volumetric area and the presence of high-risk structures (e.g., blood vessels and nerves) complicate this task. In order to determine the bone area to mill using preoperative CT images automatically, we propose an automated planning method using evolutionary multi-objective optimization for safer and more efficient milling plans. High-resolution segmentation of the adjacent risk structures is performed on preoperative CT images with a template-based approach. The maximum milling area is defined based on constraints from the risk structures and tool dimensions. Deformation fields are used to simplify the volumetric area into limited continuous parameters suitable for optimization. Finally, a multi-objective optimization algorithm is used to achieve a Pareto-optimal design. Compared with manual planning on six volumes, our method reduced the potential damage to the scala vestibuli by 29.8%, improved the milling boundary smoothness by 78.3%, and increased target accessibility by 26.4%. Assessment by surgeons confirmed the clinical feasibility of the generated plans. In summary, this study presents a parameterization approach to irregular volumetric regions, enabling automated milling area planning through optimization techniques that ensure safety and feasibility. This method is also adaptable to various volumetric planning scenarios. Full article

Background and Objectives: In this study, we assessed the utility of ultrasonography in monitoring the chemotherapeutic effects on primary thyroid lymphoma (PTL). Materials and Methods: This retrospective analysis included 17 patients with PTL who received chemotherapy from 2012 to 2022. The sonographic features were examined pre- and post-treatment using ultrasound (US) to monitor the treatment response at the first to second, third to fourth, and end cycles of chemotherapy and follow-up, and progression-free survival (PFS) and overall survival (OS) were analyzed. Results: The sonographic findings for all the patients indicated diffuse or nodular infiltration with markedly hypoechoic masses, and “stripe-shaped” high echoes and posterior acoustic enhancement were observed. Following one to two cycles of chemotherapy, a US examination revealed varying tumor reduction degrees and diminished blood flow signals. After three to four cycles of chemotherapy, the US demonstrated an evaluation efficacy comparable to that of PET-CT in cases in which the lesion had entirely disappeared postchemotherapy; however, its ability to differentiate between treatment response and residual lesions was less effective compared to that of PET-CT. After the end cycle of chemotherapy, the lesion sizes had significantly decreased compared to those at the baseline (p < 0.05). Postchemotherapy, Adler’s blood flow grades decreased significantly, with 80% graded as 0–1. Among the 10 patients with cervical lymph node enlargement, 70% showed reduced lesion sizes and blood flow signals. The cumulative 5-year PFS and OS rates were both 80% for the diffuse type and 82.5% and 78.8% for the nodular type, respectively (p > 0.05). Conclusions: US can be utilized to monitor the therapeutic response following chemotherapy for PTL, especially for early assessment and repeated dynamic monitoring, and can serve as a complementary follow-up method to PET-CT. Full article

In diagnostics, photons are used in basic methods such as computed tomography (CT) and positron emission tomography (PET), which are pivotal tools for high-resolution, non-invasive tumor detection, offering insights into tumor staging and progression. Mentioned techniques facilitate early diagnosis and the planning of therapeutic strategies. However, new methods are emerging, enhancing the precision and detail of diagnostics, such as ultra-weak photon emission (UPE) imagining, two-photon fluorescence imaging, photo acoustic imaging, and others. Therapeutically, external beam radiation therapy (EBRT) uses photons to target cancer cells while minimizing harm to healthy tissue. Photodynamic therapy (PDT), which uses light-sensitive compounds activated by specific wavelengths, represents a photon-based treatment applicable to certain malignancies. Other treatments include photo thermal therapy (PTT), radio dynamic therapy (RDT), intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and more. These constantly evolving photon-driven technologies can be used to treat a broad spectrum of cancers, such as pancreatic, prostate, breast, and skin cancers. This review article discusses the latest photon-based methods in oncology, focusing on new possibilities, solutions, perspectives, and the potential disadvantages of these approaches. Full article

Additive manufacturing (AM) refers to advanced technologies for building 3D objects by adding material layer upon layer using either electron beam melting (EBM) or selective laser melting. AM allows us to produce lighter and more complex parts. However, various defects are created during the AM process, which severely affect fatigue behavior. In the current research, the effects of the anisotropic microstructure in the in-plane and out-of-plane orientations and defects on the fatigue crack propagation rate (FCPR) and crack path were studied. A resonance machine was used to determine the fatigue crack propagation rate (da/dN vs. ΔK) from the near-threshold up to the final fracture, accompanied by in situ Acoustic Emission (AE) monitoring. Micro-Computerized Tomography (µCT) enabled us to characterize surface and microstructural defects. Metallography was used to determine the microstructure vs. orientations and fractography to classify the fatigue fracture propagation modes. Calculations of the local stress distribution were performed to determine the interactions of the cracks with the defects. In the out-of-plane direction, the material exhibited high fatigue fracture toughness accompanied by a slightly lower fatigue crack propagation rate as compared to in-plane orientations. The near-threshold stress intensity factor was slightly higher in the out-of-plane orientation as compared to that in the in-plane one, accompanied by a lower exponent of the Paris law regime. The threshold decreased with an increasing load ratio as expected for both orientations. The crack propagation direction that crosses the elongated grains plays an important role in increasing fatigue resistance in the out-of-plane direction. In the in-plane directions, the crack propagates parallel to the grain boundary, interacts with more defects and exhibits more brittle striations on the fracture surface, resulting in lower fatigue resistance. Full article

This paper examines the mechanical performance of fibre-reinforced composite sandwich structures (FRPSSs) for maritime applications, focusing on the impact bending and damage sequence after seawater exposure. Glass-fibre/epoxy facesheets with various PVC foam core configurations underwent low-velocity single and multiple impacts. An in situ moisture-uptake methodology monitored moisture ingress until saturation. Results showed moisture uptake reduced impact bending capacity and bending stiffness to varying degrees. While energy-absorption performance remained largely unchanged under single impacts, significant differences were noted for multiple impacts. Failure analysis confirmed the reductions in some damage modes such as facesheet fracture, indentation, and core shear failures, while core shearing, delamination, core/facesheet debonding, and fibre breakage were identified as the main failure modes. These insights enhance understanding and optimisation of FRPSSs for improved out-of-plane damage resistance in marine applications. Full article

The swimbladder, when present, is the main contributor to the acoustical target strength (TS) of fish. Numerical modeling of target strength must include swimbladder dimensions, orientation, and shape for the proper estimation of target strength and its directivity. Several Atlantic Bluefin tuna (Thunnus thynnus, ABFT) specimens between 90 and 100 cm of fork length were studied by performing computed tomographic (CT) post-mortems in both fresh and frozen states. ABFT swimbladder 3D models were derived for the first time to be compared with experimental TS measurements through numerical simulation methods, using the Method of Fundamental Solutions (MFS). The numerical estimation (−23.3 dB) agreed with the experimental measurement of TS (−22.1 dB) performed in a tank with tuna with a mean fork length of 100 cm, showing the importance of considering realistic swimbladder shapes and swimming behavior in the numerical simulation of TS. Full article