Thick Sections Research Articles

Photon-counting detector CT provides superior subsolid nodule characterization compared to same-day energy-integrating detector CT.

To investigate the image quality and the performance of photon-counting detector (PCD) CT compared to conventional energy-integrating detector (EID) CT in identifying subsolid nodule (SSN) characteristics. Participants with SSNs who underwent same-day EID CT and PCD CT between October 2023 and April 2024 were prospectively included. The 1.0 mm EID CT images and, subsequently, 1.0 mm, 0.4 mm, and 0.2 mm PCD CT images were reviewed to assess image noise and subjective image quality on a 5-point Likert scale. SSN characteristics, including lobulation, spiculation, pleural retraction, air cavities, intra-nodular vessel signs, internal vascular changes, and heterogeneous solid components, were evaluated. Additionally, a step-by-step observation and comparison method was used to determine the presence of any additional characteristics. Forty-eight participants (mean age: 56 ± 11 years; 16 males) with 89 SSNs were included. PCD CT significantly reduced radiation dose when using matched scans (1.79 ± 0.39 vs 2.17 ± 0.57 mSv, p < 0.001). Compared to 1.0 mm EID CT, 1.0 mm PCD CT images exhibited significantly lower objective image noise and higher subjective image quality (all p < 0.001). Compared to EID CT, PCD CT demonstrated enhanced visualization of subtle characteristics, except for lobulation, with a 0.4 mm section thickness offering a favorable balance between ultra-high resolution and perceived image quality for radiologists. PCD CT facilitated radiation dose reduction and outperformed conventional EID CT in terms of image quality and visualization of SSN characteristics. Question PCD CT, featuring ultra-high-resolution mode acquisition and a thinner reconstruction, has not been fully explored for characterizing SSNs. Findings Compared to EID CT, PCD CT was associated with lower objective image noise, higher subjective image quality, and superior SSN characterization. Clinical relevance PCD CT effectively reduced the radiation dose delivered to the patients and enabled more precise SSN characterization.

Line-dropped gelatin multi-element calibration standards in LA-ICP-MS: a statistically verifying comparison with cryosectioned homogenized lung and liver as matrix-matched calibration standards and as corresponding reference materials.

Calibrations in LA-ICP-MS are typically very time-consuming and complex, as they need to be matched to the samples being measured and sectioned on a microtome. Alternatively, gelatin can be in droplet form or as a section, which is a more recent development. In this study, we report on investigations where hot multi-element gelatin solutions are placed in a linear fashion on microscopic slides to conduct comparative statistical observations between doped tissue homogenates from the liver and lung. The tissue homogenates served as both samples (complete ablation) and calibration standards (partial ablation) for verification purposes. We explored the effects of different laser fluences (0.50-1.50J/cm2), gelatin contents (0.3-20.0%) and section thicknesses (10-30µm). To do this, we evaluated the samples by calculating median and mean values over the entire section with and without removal of elementary spikes (de-spiking). A reduction in distribution was achieved with averaging. The data was normalized using 13C as an internal standard. In these experiments and under these measurement conditions, it was observed that the selected laser fluences, gelatin contents, and section thicknesses did not visibly affect the results, making them comparable. Each sample could be assessed with each gelatin calibration, allowing for determination of expected reference values. Despite interruptions in the measurement operation, due to the high number of measurements, where samples and calibrations could not be analyzed in one measurement run, no negative effects of stopping and starting the LA-ICP-MS were observed.

Reconstructing 3D histological structures using machine learning (artificial intelligence) algorithms.

Histomorphometry is currently the gold standard for bone microarchitectural examinations. This relies on two-dimensional (2D) sections to deduce the spatial properties of structures. Micromorphometric parameters are calculated from these sections based on the assumption of aplate-like 3D microarchitecture, resulting in the loss of 3D structure due to the destructive nature of classical histological processing. To overcome the limitation of histomorphometry and reconstruct the 3D architecture of bone core biopsy samples from 2D histological sections, bone core biopsy samples were decalcified and embedded in paraffin. Subsequently, 5 µm thick serial sections were stained with hematoxylin and eosin and scanned using a3DHISTECH PANNORAMIC 1000 Digital Slide Scanner (3DHISTECH, Budapest, Hungary). Amodified U‑Net architecture was trained to categorize tissues on the sections. LoFTR feature matching combined with affine transformations was employed to create the histologic reconstruction. Micromorphometric parameters were calculated using Bruker's CTAn software (v. 1.18.8.0, Bruker, Kontich, Belgium) for both histological and microCT datasets. Our method achieved an overall accuracy of 95.26% (95% confidence interval (CI): [94.15%, 96.37%]) with an F‑score of 0.9320 (95% CI: [0.9211, 0.9429]) averaged across all classes. Correlation coefficients between micromorphometric parameters measured on microCT imaging and histological reconstruction showed astrong linear relationship, with Spearman's ρ‑values of 0.777, 0.717, 0.705, 0.666, and 0.687 for bone volume/tissue volume (BV/TV), bone surface/TV, trabecular pattern factor, trabecular thickness, and trabecular separation, respectively. Bland-Altman and mountain plots indicated good agreement between the methods for BV/TV measurements. This method enables examination of tissue microarchitecture in 3D with an even higher resolution than microcomputed tomography (microCT), without losing information on cellularity. However, the limitation of this procedure is its destructive nature, which precludes subsequent mechanical testing of the sample or any further secondary measurements. Furthermore, the number of histological sections that can be created from asingle sample is limited.

Experimental and numerical investigation on damage mechanism in asymmetric tapered laminates under tensile loading

It is one of the most advanced technologies to use automated fiber placement (AFP) to manufacture aero-engine composite blades. The layup sequence of composite blades has strong designability due to the variation of section thickness. In this article, tapered laminates are manufactured by AFP. The influence of different resin pockets and laying methods on the properties of tapered laminates are analyzed by tensile test, finite element modeling and macroscope images. The specimens are analyzed by failure mode, strength and crack propagation and suggestions for improvement are put forward. The results show that the resin pocket height and taper ratio have a great influence on the tensile strength. The 1:30 taper ratio has a higher strength than the 1:20 taper ratio, at least 54.22% higher. In addition, the crack near the thin end of the resin pocket is tend to cause cracks, and the delamination is also tend to reach this position. Experimental measurements and FEM results correlate very well.

Abstract A033: Integrating spatial transcriptomics and second harmonic generation imaging to identify targets of supermere-associated Discoidin Domain Receptor 1 involved in collagen alignment

Abstract Immune checkpoint blockade has been shown to be an effective treatment for colorectal cancers (CRCs) highly infiltrated by CD8+ T cells. However, there is a paucity of CD8+ T-cell infiltration in the majority of CRCs. We previously identified the collagen-activated receptor Discoidin Domain Receptor 1 (DDR1) as a member of a four-gene signature associated with T-cell exclusion in CRC. The cleaved ectodomain (cECD) of DDR1 induces collagen alignment, leading to T-cell exclusion in a breast cancer model. We found that almost all DDR1 cECD is found in supermeres, a novel secreted nanoparticle identified by our lab, and that DDR1 cECD is required for supermere signaling in recipient cells. We hypothesized that supermere-associated DDR1 cECD signals to CRC stromal cells, leading to collagen alignment. To test this hypothesis, we developed a method to determine which genes are associated with collagen alignment and DDR1 expression. To do this, 30 μm thick CRC sections are imaged using a Nikon AX multiphoton microscope by second harmonic generation imaging, which permits label-free imaging of collagen fibers. Spatial heatmaps of the collagen alignment are generated from the resulting images. Spatial transcriptomics is performed on a serial tumor section using the Visium v2 platform and the gene expression matrix is integrated with the collagen alignment heatmap data. As proof-of-principle, two CRC tumors have been analyzed using this method. Highly aligned regions were found to be associated with expression of genes involved in extracellular matrix organization, keloidal collagen and specific fibroblast subtypes. Genes which may be regulated by DDR1 cECD and be involved in collagen alignment will be confirmed at the protein level by multiplexed immunofluorescence on serial sections and in vitro experiments. This method will provide a rich dataset to elucidate the roles of supermeres and DDR1 cECD in T-cell exclusion and collagen fiber alignment and may support the discovery of new strategies to overcome immune exclusion in CRC. Citation Format: Maxwell S. Hamilton, Oleg Tutanov, Harsimran Kaur, Alan J. Simmons, Clark Massick, Kasey Vickers, Ken S. Lau, Ambra Pozzi, Robert J. Coffey. Integrating spatial transcriptomics and second harmonic generation imaging to identify targets of supermere-associated Discoidin Domain Receptor 1 involved in collagen alignment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A033.

Reliability and Fire Performance of Built-up (Battened) Cold-formed Steel Columns: Numerical study

Cold-formed steel (CFS) columns play a crucial role in modern construction due to their lightweight, prefabricated, and recyclable characteristics, contributing significantly to structural safety and reliability. However, unprotected CFS columns lose their load-bearing capacity within 10-15 minutes under fire conditions. This study reviews recent advancements aimed at improving the fire resistance of CFS columns, focusing on factors such as steel thickness, grade, cross-sectional shape, and fire protection materials. Using ABAQUS software, validated against experimental data, parametric studies reveal that thicker sections and higher-grade steels enhance fire resistance, delaying structural failure. Fire protection strategies, such as plasterboard encasement, further bolster safety. The Complex cross-sectional shape demonstrated the highest load capacity (178.51 kN), while G450 steel outperformed other grades in both load capacity and fire resistance. Columns with 1.95 mm thickness provided the longest failure time (73.49 minutes).

A Study on a Novel Production Forecasting Method of Unconventional Oil and Gas Wells Based on Adaptive Fusion

Reliable forecasting of unconventional oil and gas well production has consistently been a hot and challenging issue. Most existing data-driven production forecasting models rely solely on a single methodology, with the application effects of other mainstream algorithms remaining unclear, which to some extent hinders the generalization and utilization of these models. To address this, this study commences with data preparation and systematically develops a novel forecasting model based on the adaptive fusion of multiple mainstream data-driven algorithms such as random forest and support vector machine. The validity of the model is verified using actual production wells in the Marcellus. A comprehensive evaluation of multiple feature engineering extraction techniques concludes that the main controlling factors affecting the production of Marcellus gas wells are horizontal segment length, fracturing fluid volume, vertical depth, fracturing section, and reservoir thickness. Evaluation models based on these primary controlling factors reveal significant differences in prediction performance among mainstream data-driven methods when applied to the dataset. The newly developed model based on adaptive fusion optimized by genetic algorithms outperforms individual models across various evaluation metrics, which can effectively improve the accuracy of production forecasting, demonstrating its potential for promoting the application of data-driven methods in forecasting unconventional oil and gas well production. Furthermore, this will assist enterprises in allocating resources more effectively, optimizing extraction strategies, and reducing potential costs stemming from inaccurate predictions.

Performance of high-resolution diffusion-weighted magnetic resonance imaging for detecting clinically occult early breast cancers: a multi-reader study.

To compare mammography, breast ultrasound (US), high-resolution diffusion-weighted magnetic resonance imaging (DW-MRI), dynamic contrast-enhanced breast MRI (DCE-MRI), and their combinations for detecting clinically occult early breast cancers (EBCs), including ductal carcinoma in situ (DCIS). Three hundred and three consecutive women with screening imaging-detected early breast cancers (60 pure DCIS, 36 DCIS with microinvasion, and 207 invasive carcinoma less than 20mm) who underwent breast MRI at 3T including DW-MRI (b-values of 0, 800 and 1200s/mm2; in-plane resolution, 1.1 × 1.1 mm2 or 1.3 × 1.3 mm2; section thickness, 3mm) were retrospectively reviewed. Three radiologists independently reviewed each examination. Statistical analysis included Chi-square test, McNemar test for comparison of cancer detection rates, and Fleiss' Kappa for interreader agreement. Mixed-effect logistic regression analysis was employed to evaluate factors associated with cancer detection on DW-MRI. The overall cancer detection rates were 54.8% on mammography, 71.0% on breast US, 81.5% on DW-MRI, and 87.1% on DCE-MRI. On McNemar test, DW-MRI detected more cancers than mammography (adjusted p < 0.001), and its combination with mammography showed a similar cancer detection rate to DCE-MRI combined with mammography (adjusted p = 0.808). On multivariable analysis, histologic type, lesion size, ADC and CNR on DW-MRI were independent factors for cancer detection on DW-MRI. The interreader agreement for cancer detection was moderate to substantial (Fleiss' kappa: 0.52-0.65) across each modality. High-resolution DW-MRI plus mammography showed comparable cancer detection rate to DCE-MRI plus mammography for detecting clinically occult EBCs including DCIS.

The Lomonosov Ridge, central Arctic Ocean - the world's longest submarine ridge of continental origin: outline of the history of exploration, morphology, sediment deposition, and exhumation of the North American and Central ridge segments

We have accessed the North American segment of the Lomonosov Ridge in the central Arctic Ocean by a 12-month hovercraft expedition on drifting sea ice and revisit legacy seismic data to explore the geological history of the ridge. Seismic reflection images on the North American segment resemble the acoustic reflection sequence calibrated by scientific drilling at the ACEX site on the Central ridge segment, although the thickness of the Cenozoic sediment section is reduced to 70%. A base-Cenozoic unconformity is present north of about 88 o 30’ N and older sediments dip towards the Makarov Basin along the entire ridge segment. During the Eocene, sediment drifts were deposited along the flanks on top of the North American segment north of 87 o N as well as next to the ACEX drill site on the Central segment of the ridge. Two local sediment lenses deposited at the Canadian end of the Lomonosov Ridge document local ridge-uplift events at about 56 Ma and 48 Ma during the Eurekan Orogeny. Compressional velocity gradients derived from published seismic reflection/refraction measurements are consistent with 1-3 km of Cretaceous/early Cenozoic exhumation of an up to 500 km wide swath of continental crust along the polar continental margin including the Lomonosov Ridge, Svalbard and Franz Josef Land .

Expression Of Nuclear Factor IC And Detection Of Calcium During Odontogenesis And Odontogenic Tumors

Background: Tooth development is a complex and well-coordinated developmental process that is achieved through a series of reciprocal interactions between dental epithelium and neural crest-derived ectomesenchyme. The dental epithelium gives rise to the outer and inner enamel epithelium from which ameloblasts differentiate, whereas ectomesenchymal cells differentiate into odontoblasts. Nfic has a specific function as a key regulator of dentin formation. Nfic signaling modulates late odontoblast differentiation and mineralization. Both dental papilla cells and dental follicle cells have extensive proliferation ability, expressed similar cell surface antigens and were capable of forming hard tissue. But dental papilla cells had diverse calcium expression than that in dental follicle cells. Most of the literatures have focused the influence of Nfic and OPN in tooth germs. There is no clear evidence to elicit their influence in odontogenic tumours. Aims and objective: The present study was intended to evaluate expression and elicit the influence of Nfic and calcium binding protein (OPN) in odontogenesis and odontogenic tumors. Materials and methods: The study comprised of 20 tooth germs from human foetuses of terminated pregnancies with age ranging between 10 to 36 weeks and 30 paraffin embedded blocks of histopathologically diagnosed odontogenic tumours. Five micrometer thick sections were taken and stained immunohistochemically with Nfic and OPN and evaluated for their expression in tooth germs and in odontogenic tumors. Results: In tooth germs, Nfic showed strong expression in odontoblasts and OPN showed strong expression in enamel matrix. Nfic showed positive expression in odontogenic tumours and OPN showed strong expression in calcification foci in AOT. Conclusion: The present study was an attempt to assess the influence of Nfic during crown formation. Expression of Nfic in tooth germs confirmed its influence in crown formation. Expression of OPN suggested that it promotes mineralization in tooth germs, bone formation and calcification focus in odontogenic tumours

Morphological Evaluation of Corpus Callosum Atrophy Over Time in Relapsing Remitting Multiple Sclerosis

Objective: Multiple sclerosis (MS) is a chronic central nervous system (CNS) disease that generally affects young adults and is marked by inflammation, demyelination, and neurodegeneration. Magnetic resonance imaging (MRI) is widely used diagnosis tool for relapsing remitting MS (RRMS). Corpus callosum (CC), the largest commissural tract in brain which is associated with both cognitive and physical impairment by atrophy in MS. Our study aimed to evaluate CC in RRMS patients using MR images and compare it to measurements from healthy controls within the same age. Methods: We manually measured changes in CC thickness in T1 brain MR images of RRMS patients in 2017, 2019, and 2022. Results: Our results showed that control group had greater thickness, length, and index values in all CC sections compared to patient group. Additionally, a significant difference was observed in thickness of genu and splenium sections and CC index between patient and control groups. However, no significant difference was detected in truncus part of CC or overall CC length. CC measurements in patient group decreased over time, with 1st MRI showing greater values than 2nd and 3rd MRI scans. Furthermore, there was a statistically significant difference in thickness of truncus part of CC and volume values of subcortical areas between 2nd-3rd and 1st-3rd MRI measurements. Conclusion: As a result of these findings, our study provides important information about changes in CC measurements for MS patients.

Morphological Changes in the Lumbar and Abdominal Muscles in Individuals with Sacralization

Although sacralization is one of the most common congenital anomalies of the spine, its effect on surrounding muscles is still not well known. This study was conducted to determine the size of the lumbar and abdominal muscles of the individuals with sacralization and to compare with the control group. Eighty-five participants with sacralization phenomena and fifty-six asymptomatic participants were included in this study. Sacralization was classified according to the Castellvi classification. The cross-sectional area of the multifidus lumborum, erector spinae and rectus abdominis muscles, and the section thicknesses of external abdominal oblique, internal abdominal oblique and transversus abdominis muscles were measured bilaterally on axial computed tomography images at the L1-2 and L4-5 levels. ANCOVA revealed that there is no any significant group*side interaction effect regarding muscles sizes in terms of two groups in L1-L2 and L4-L5. In addition, ANCOVA revealed a both side effect [(p=.020; η2p=.038)] and group*side interaction effect [(p=.010; η2p=.049)] regarding length of the L5 transverse process (p˃.05). Regardless of low back pain, muscle sizes are not associated with the sacralization phenomenon.

Section thickness is identical for the sliding microtome and rotary microtome under the continuous cooling device condition

To date, no report has compared section thickness (ST) between the sliding microtome (SM) and rotary microtome (RM). We used the ice pack (IP) condition, in which the paraffin block was not cooled during slicing, and a continuous cooling device (CCD) for continuous cooling during slicing. The ST was greater for the SM than the RM in the IP condition, but it was identical between the devices under the CCD condition. Thus, we used the CCD condition for subsequent studies. In formalin-fixed, paraffin-embedded (FFPE) fish sausage blocks, the ST of the tissue surface (T-surface) was significantly concaved compared to that of the paraffin surface (P-surface) for both microtomes. On the contrary, in FFPE human kidney blocks, ST did not differ between the T-surface and P-surface. Furthermore, the eosin-positive area of PAM-stained specimens was affected by ST, and the color tone of the thickest sample differed from that of the median or thinnest sample. Our data indicated that we should use CCD conditions to ensure that ST is uniform regardless of the type of microtome. In addition, for quantitative analysis, we should utilize ST measure equipment and specimens with a constant ST.

Behaviours of novel prefabricated RAC-HSC composite beams subjected to fire: An experimental and numerical study

The combination of different types of concrete in prefabricated concrete structures may have promising potential in optimizing both structural mechanics and fire performance. Therefore, the fire-resistance tests of proposed U- and C-types recycled aggregate concrete (RAC) - high-strength concrete (HSC) composite concrete beams were carried out. Their thermal and structural behaviours were extensively analyzed and compared with those of monolithic beams. Subsequently, a sequential thermal-mechanical analysis model was developed. The test results revealed that the novel composite RAC-HSC beams exhibited lower mid-span deflection and less damage than the monolithic HSC beams under fire exposure. The internal temperatures of specimens with RAC were significantly lower than that of specimens without RAC. Based on the numerical analysis, the predicted fire resistance limits for the novel RAC-HSC composite beam were approximately 30 min longer than that for the monolithic HSC beam. The thickness of the RAC section in RAC-HSC composite beams was suggested by parametric studies. Generally, this study proved that the fire performance of the proposed novel RAC-HSC composite beams was better than that of HSC and RAC monolithic beams.

Axial capacity of cold-formed steel channel sections with slits

Cold-formed steel (CFS) studs often include slits in their webs to improve thermal performance. However, the inclusion of such slits reduces their axial capacity. The literature contains limited experimental studies on the axial capacity of these studs with slits, and no non-linear elasto-plastic finite element studies have been reported. This research aims to address this gap. Non-linear elasto-plastic finite element models were developed and validated against experimental test results. A parametric study consisting of 960 finite element analysis (FEA) models was then conducted, covering the effects of different channel dimensions, slit sizes, section thicknesses, and stud lengths. Ultimate axial capacities obtained from these analyses were compared to the current codified direct strength method (DSM) predictions as per the Australian/New Zealand Standard AS/NZS 4600. Finally, design recommendations in the form of strength reduction factors are proposed. Based on these recommendations, modified DSM design equations with a reliability index above 2.5 are presented.

Investigation of PLGF, sFlt-1 expression in Plasenta Previa, Plasenta Accreta and Normotensive Plasentas in the 3rd Trimester of Pregnancy

Background: We aimed to immunohistochemically examine the expression level of Placental growth factor (PLGF) and Soluble FMS-like tyrosine kinase-1 (sFlt-1) proteins in normotensive, Placenta accreta (PA) and Placenta previa (PP). Materials and Methods: Three groups were created for the study: 20 Nomotensive placentas, 20 PP and 20 PA from women diagnosed with placenta samples. 4-6 μm thick sections were taken from the placentas, PLGF and sFlt-1 immunostaining were applied to the obtained sections, and their expression intensities and localizations in the tissues were determined. Results: As a result of our observations, normotensive placenta group; sFlt-1 expression was observed in hofbauer cells and syncytial nodes and PLGF positive expression was observed in nuclei of muscle cells in some tunica media region. PP and PA group; sFlt-1 expression was positive in decidua cells, hofbauer cells and dilated vascular endothelium. PP and PA group; negative PLGF expression was observed in syncytial nodes and positive PLGF expression was observed in hofbauer cells and endothelial cells. There was a significant difference between normotensive, PP and PA groups (p&amp;lt;0.05). Conclusions: It can be thought that sFlt-1 and PLGF may be important signal stimulators and markers in the trophoblastic degeneration, apoptotic cells, increase in angiogenesis and imbalance in implanta-tion seen in cases of PP and PA.

Targeted microscopic rare cell retrieval yields sufficient deoxyribonucleic acid for molecular testing in fixed tissue with low tumor fraction

Abstract Introduction/Objective DNA extracted from formalin-fixed paraffin-embedded tissue (FFPE) blocks is often utilized for molecular oncologic testing. Cases with low tumor fraction often fail to obtain adequate tumor for molecular testing. We hypothesized that targeted retrieval of visualized tumor cells from FFPE sections, including those with low tumor fraction, could yield sufficient DNA for molecular testing. Methods/Case Report Unstained sections of various thicknesses were cut from low tumor fraction blocks and visualized by light microscopy and the RareCyte CyteFinder II (Seattle, WA). Microscopic cell retrieval was performed on the RareCyte using 40 µm diameter needles from identified regions of interest. Samples were deparaffinized using Zymo Research (Tustin, CA) solution, and digested and purified using Zymo-Spin Column technology. Sample DNA was quantified with NanoDrop Spectrophotometer (Chino, CA). Results (if a Case Study enter NA) Regions of interest were morphologically identifiable on 4-10 µm thick sections and harder to visualize on 12 µm thick sections. Targeted microscopic cell retrieval was performed with 40 µm diameter needles. Retrieval was performed from 26 to 34 regions of interest per sample and pooled for molecular testing. Samples (n=4) yielded a mean of 81.0 ng of DNA ± 18.4 ng (1.8 ng/µL ± 0.4 ng/µL) and a median of 87.75 ng (1.95 ng/µL). Conclusion Targeted microscopic cell retrieval from low tumor fraction FFPE slides using the RareCyte CyteFinder II can provide sufficient DNA material for molecular testing. Application of this technology has the possibility of recovering sufficient tumor DNA for molecular testing from specimens that may be deemed unsuitable for molecular testing according to current standards. We aim to focus on increasing sample size and completing comprehensive molecular analysis as we continue to expand this work.

Influence of manufacturing errors on the aerodynamic working stability of axial flow compressors

In turbomachinery, manufacturing errors in blades have been found to impact aerodynamic performance. This paper aims to investigate the effect of manufacturing errors on the stability of compressor operation. To this end, a geometric uncertainty reduced-order model is developed to generate the normal profile error of rotor blades based on specific tolerances, considering the simultaneous variation of blade parameters during manufacturing. The stability margin improvement of the compressor is then calculated using computational fluid dynamics (CFD), and a neural network is employed to predict the relationship between the uncertainty input variables and the stability margin improvement. Finally, a large number of samples are generated using the Quasi-Monte Carlo method, and Sobol sensitivity analysis is performed. According to the results, manufacturing errors can reduce the stability margin by an average of 0.9% and up to 3% in the limiting case. The parameters that have the greatest impact on the stability of the compressor are the blade chord length of the hub section and the maximum thickness of the tip section. These two parameters affect blade tip blockage by influencing spanwise secondary flow on the suction surface. Additionally, the decrease in maximum thickness at the tip section affects the separation of the boundary layers on the suction surface, resulting in additional effects.

Innovative D-process MIG welding for enhanced performance of thick sections of MDN 250 in aerospace applications

Maraging steel, known for its exceptional strength, toughness and ductility, is widely used in aerospace and hypersonic missile manufacturing. The present study investigates the feasibility of joining 12 mm thick sections of maraging steel using advanced D-Process MIG welding technology. The D-Process integrates different welding modes such as MIG, Single Pulse-MIG and Double Pulse-MIG to optimize welding parameters, minimizing heat input. Additionally, the research investigates the influence of various post-weld heat treatments (PWHTs) on the performance of welded joints. The PWHTs included in the study are Ageing Treatment (AT), Solution Treatment + Ageing Treatment (SAT) and Homogenizing Treatment + Solution Treatment + Ageing Treatment (HSAT). Metallographic and mechanical tests were conducted on as-welded (AW) and PWHT conditions. Results showed the HSAT condition yielded superior properties with an average UTS of 1771 MPa, YS of 1734 MPa, and an average fracture toughness (FT) of 88 MPa√m. This underscores the efficacy of D-Process welding in meeting stringent requirements for maraging steel in aerospace and high-performance applications.

Section thickness effect on microstructure, mechanical and electrical properties of permanent steel mold cast eutectic Al-1.8Fe alloy

Abstract A eutectic aluminum alloy, with a composition of 1.8 wt% iron, underwent casting using permanent steel mold casting (PSMC) across three distinct section thicknesses: 2mm, 8mm, and 20mm. The microstructure of the as-cast alloy was analysed by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microstructure analyses indicated that the cast Al-1.8Fe alloy consisted of the primary Al phase, eutectic Al phase, micron-sized eutectic Al-Fe phase, and nano-sized eutectic Al-Fe phase. The results of tensile testing revealed notable improvements in mechanical properties for the cast Al-1.8Fe alloy as the section thickness decreased from 20mm to 2mm. Specifically, Ultimate Tensile Strength (UTS), Yield Strength (YS), elongation (ef), modulus, toughness, resilience, and electrical conductivity increased from 85.99 MPa, 28.33 MPa, 15%, 63 GPa, 8.58 MJ/m3, 6.37 kJ/m3, 48.44 %IACS to 157.74 MPa, 84.83 MPa, 19%, 66.4 GPa, 23.87 MJ/3, 54.17 kJ/m3, 51.09 %IACS, respectively. Conversely, porosity levels decreased from 5.17% to 1.87% as thickness increased from 2mm to 20mm. The enhanced mechanical properties and electrical conductivity observed in the 2mm sample are attributed to its fine microstructure and low porosity. Additionally, SEM fractography revealed that fracture behavior in PSMC Al-1.8Fe was influenced by section thickness.