Section Profile Research Articles

Micro-scale modeling and analysis on material removal mechanisms for flexible ball-end tool polishing incorporating the curvature effect

Optical freeform surfaces (OFS) have been extensively employed as core components in advanced optical systems for their excellent performances. However, the surface complexity and the high surface accuracy do impose challenges to the processing of OFS, especially the surface form maintaining or control during polishing. As one of the promising ultra-precision machining technologies to fabricate OFS, the flexible ball-end tool (FBET) polishing becomes available due to its attractive technical advantages. Nevertheless, there are still lack of more comprehensive insights on material removal mechanisms for FBET polishing incorporating the curvature effect, particularly from a microscopic scale, which is of great significance to determine the surface quality and form control in ultra-precision polishing process. In this paper, different from those published macro-scale Preston law-based models, a micro-scale material removal model is developed based on the mutual interaction of the slurry, polishing pad and curved workpiece among the FBET polishing interfaces with micro-contact theory and tribology theory, wherein various parameters embodied in FBET polishing are formulated quantitatively, such as slurry characteristics, pad properties, tool features, processing conditions, as well as workpiece curvature effect. The FBET is designed and adopted to conduct the spot polishing experiments within the concave curvature radius range from 75 mm to 225 mm, wherein the curvature radius range from 225 mm to 800 mm is theoretically chosen as an extension of this research. The predicted results agree well with the experimentally measured section profiles of polishing spots, thereby demonstrating the correctness and effectiveness of the proposed model. Furthermore, the effective relative velocity U together with the separation gap d between reference plane and workpiece surface are known as the two key parameters to account for the material removal mechanisms, and the latter is figured out to be the sensitive one to the curvature effect rather than the former. Through the analysis of key parameters, the established model is capable of helping to strengthen the understanding of material removal mechanisms for FBET polishing with the consideration of curvature effect, addressing those cannot be interpreted by the classical Preston equation previously, which is meaningful for precision control of material removal during polishing of OFS.

Effect of cumulative plastic deformation on microstructure and strengthening mechanism of extruded Al-Zn-Mg-Cu alloy

Al-Zn-Mg-Cu alloy profiles are widely used as aircraft components because of lightweight and high strength. The section of thin-walled profile is easy to have unavoidable heterogeneous strain. However, the influence mechanism of different cumulative plastic strains (CPS) on the material properties at different cross-section locations needs to be further clarified. This study carried out an extrusion experiment to study the influence of CPS on the microstructure, properties, and strengthening mechanisms by TEM, SEM and XRD. Results show that the strength and micro-hardness are positively correlated with CPS, while the elongation exhibits an inverse correlation. The orientation relationships between different micro- and nano-scale precipitates and the matrix were characterized. The strengthening mechanisms under different CPS were clarified. It was found that the contribution of solid solution strengthening is 22.6 % under the maximum cumulative strain, while Orowan strengthening accounts for 20.3 %. In contrast, these contributions are 30.2 % and 11.9 % under lower cumulative strain, respectively. Specimens at low CPS have the precipitated phase bands parallel to the extrusion direction, while the high CPS induces smaller and dense precipitated phases in the matrix and grain boundaries, resulting in precipitate-free zones with a width of 200–500 nm at the sub-grain boundary, which reduces the strengthening effect at the grain boundary. The research findings can guide for optimizing the heat treatment processes of thin-walled profiles.

Unsupervised Machine Learning for Data-Driven Rock Mass Classification: Addressing Limitations in Existing Systems Using Drilling Data

AbstractRock mass classification systems are crucial for assessing stability and risk in underground construction globally and guiding support and excavation design. However, these systems, developed primarily in the 1970 s, lack access to modern high-resolution data and advanced statistical techniques, limiting their effectiveness as decision-support systems. We outline these limitations and describe how a data-driven system, based on drilling data, can overcome them. Using statistical information extracted from thousands of MWD-data values in one-meter sections of a tunnel profile, acting as a signature of the rock mass, we demonstrate that well-defined clusters can form a foundational basis for various classification systems. Representation learning was used to reduce the dimensionality of 48-value vectors via a nonlinear manifold learning technique (UMAP) and linear principal component analysis (PCA) to enhance clustering. Unsupervised machine learning methods (HDBSCAN, Agglomerative Clustering, K-means) clustered the data, with hyperparameters optimised through multi-objective Bayesian optimisation. Domain knowledge improved clustering by adding extra features to core MWD-data clusters. We structured and correlated these clusters with physical rock properties, including rock type and quality, and analysed cumulative distributions of key MWD-parameters to determine if clusters meaningfully differentiate rock masses. The ability of MWD data to form distinct rock mass clusters suggests substantial potential for future classification systems using this objective, data-driven methodology, minimising human bias.

Skin and hair of the Tibetan Hamster (<i>Urocricetus kamensis</i>, Cricetidae, Rodentia): A comparative morphological analysis

For the first time, using light and scanning electron microscopy, the fine structure of the skin and its derivatives (glands, hairs, whiskers) was studied in adult male and female Tibetan hamsters (Urocricetus kamensis Satunin 1903), a unique species of the subfamily Cricetinae that lives only in the highlands of the Tibetan Plateau. A comparative morphological analysis of the skin, along with features of its similarity with the skin of other hamsters, revealed a number of characteristic features in the Tibetan hamster that contribute to the adaptation of this species to the harsh mountain climate conditions with sharp seasonal and daily temperature fluctuations: abundant subcutaneous fatty tissue, a special hair structure that provides effective heat protection due to a significant change in the volume of inert air in the fur: significant hair density, wavy arrangement of rows of hairs and the profile of the lower sections of the guard hairs. The presence of relatively long and thick guide hairs in the fur serves to protect the coat in rocky habitats. The array of specific skin glands is little compared to other Cricetinae; no mid-ventral and flank glands were found, this being unique for representatives of the subfamily, but this requires confirmation based on more abundant material.

Parametric design of curved hydrocyclone using data points and its separation enhancement mechanism

Based on parametric design of curves using data points, two novel hydrocyclones were designed: Spline-Curved-Cone hydrocyclone (H2) and Expassoc-Curved-Cone hydrocyclone (H3). These designs are improvements on the traditional biconical hydrocyclone (H1). Numerical simulations and experimental validation by PIV measurement were used to investigate the effects of cone section profiles on the flow characteristics and separation efficiency. The results showed both H2 and H3 achieved higher separation efficiency than H1. Specifically, the highest efficiency of H3 increased by 24.71%, and that of H2 increased by 16.22% compared with H1. It was also found the curved design of cone section profile directly affects the tangential velocity distribution and pressure distribution of the flow field inside hydrocyclones. H3 exhibited better flow field stability and highest separation efficiency due to its optimized cone section space and flow structure. This study provides scientific basis and data support for the optimization and industrial application of the cylinder-on-cone hydrocyclones.

Seq-Scope: repurposing Illumina sequencing flow cells for high-resolution spatial transcriptomics.

Spatial transcriptomics technologies aim to advance gene expression studies by profiling the entire transcriptome with intact spatial information from a single histological slide. However, the application of spatial transcriptomics is limited by low resolution, limited transcript coverage, complex procedures, poor scalability and high costs of initial setup and/or individual experiments. Seq-Scope repurposes the Illumina sequencing platform for high-resolution, high-content spatial transcriptome analysis, overcoming these limitations. It offers submicrometer resolution, high capture efficiency, rapid turnaround time and precise annotation of histopathology at a much lower cost than commercial alternatives. This protocol details the implementation of Seq-Scope with an Illumina NovaSeq 6000 sequencing flow cell, allowing the profiling of multiple tissue sections in an area of 7 mm × 7 mm or larger. We describe the preparation of a fresh-frozen tissue section for both histological imaging and sequencing library preparation and provide a streamlined computational pipeline with comprehensive instructions to integrate histological and transcriptomic data for high-resolution spatial analysis. This includes the use of conventional software tools for single-cell and spatial analysis, as well as our recently developed segmentation-free method for analyzing spatial data at submicrometer resolution. Aside from array production and sequencing, which can be done in batches, tissue processing, library preparation and running the computational pipeline can be completed within 3 days by researchers with experience in molecular biology, histology and basic Unix skills. Given its adaptability across various biological tissues, Seq-Scope establishes itself as an invaluable tool for researchers in molecular biology and histology.

Loss of Surfactant Protein A Alters Perinatal Lung Morphology and Susceptibility to Hyperoxia-Induced Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is a condition of poor alveolar formation that causes chronic breathing impairment in infants born prematurely. Preterm lungs lack surfactant and are vulnerable to oxidative injuries driving the development of BPD. Our recent studies reported that surfactant protein A (SP-A) genetic variants influence susceptibility to neonatal lung disease. SP-A modulates activation of alveolar macrophages and parturition onset in late gestation. We asked whether a lack of SP-A alters alveolarization in a mouse model of hyperoxia-induced BPD. SP-A-deficient and control newborn mice were exposed to either clinically relevant 60% O2 hyperoxia or normoxia for 5-7 days. Alveolar formation was then assessed by mean linear intercept (MLI) and radial alveolar count (RAC) measurements in lung tissue sections. We report that the combination of SP-A deficiency and hyperoxia reduces alveolar growth compared to WT mice. The morphometric analysis of normoxic SP-A-deficient lungs showed lower RAC compared to controls, indicating reduced alveolar number. In the presence of hyperoxia, MLI was higher in SP-A-deficient lungs compared to controls. Differences were statistically significant for female pups. Spatial proteomic profiling of lung tissue sections showed that hyperoxia caused a 4-fold increase in the DNA damage marker γH2Ax in macrophages of SP-A-deficient lungs compared to normoxia. Our short report suggests an important role for SP-A in perinatal lung development and the protection of lung macrophages from oxidant injury. These studies warrant future investigation to discern the temporal interaction of SP-A, gender, oxidant injury, and lung macrophages in perinatal alveolar formation and development of BPD.

Evaluation Methods and Coupled Optimization at Macro- and Micro-Scales for Profiled Ring Rolling of Inconel718 Alloy.

The forming quality of profiled ring rolling not only encompasses macroscopic accuracy but also emphasizes the microstructure. Due to the multiple process parameters and complex metal flow during profiled ring rolling, the various forming defects are difficult to control and difficult to study theoretically. The objective of this study is to establish a comprehensive method for evaluating the forming quality of profiled rings, which considers both the macroscopic forming accuracy and the microstructure. Firstly, the synthetic size factor was defined, and the evolutionary relation between the section forming rate and the diameter growth rate of E-section ring rolling was analyzed in detail. The synthetic size factor can be used to describe the dimensional evolution and evaluate the forming accuracy of the profiled ring rolling process. Taking into full consideration the features of intermittent deformation in local areas, a microstructure evolution model of the Inconel718 alloy during E-section ring rolling, which can accurately predict the recrystallization volume fraction and average grain size of the final ring, was established. Then, combined with finite element simulation, the influence of the rotation speed of the driving roll on the macro-size evolution and microstructure was systematically analyzed. The results indicate that there is often a discrepancy between dimensional accuracy and microstructure uniformity in the optimization trend. For instance, the higher the rotation speed of the driving roll is, the more uniform the microstructure is, but the more difficult it is for the section profile to form. Finally, combined with response surface methodology (RSM), multi-parameter optimization was carried out with section forming accuracy and grain uniformity as the optimization objectives. By using the optimal parameters, an E-section ring with a complete profile and a uniform microstructure was obtained, with a maximum prediction error of the recrystallization volume fraction lower than 5%. The results show that the macroscopic and microscopic quality evaluation methods proposed in this study, as well as the optimization method combining RSM, can be effectively applied to the process optimization of profiled ring rolling.

Stereologically adapted Crofton formulae for tensor valuations

The classical Crofton formula explains how intrinsic volumes of a convex body K in n-dimensional Euclidean space can be obtained from integrating a measurement function at sections of K with invariantly moved affine flats. We generalize this idea by constructing stereologically adapted Crofton formulae for translation invariant Minkowski tensors, expressing a prescribed tensor valuation as an invariant integral of a measurement function of section profiles with flats. The measurement functions are weighed sums of powers of the metric tensor times Minkowski valuations. The weights are determined explicitly from known Crofton formulae using Zeilberger's algorithm. The main result is an exhaustive set of measurement functions where the invariant integration is over flats.With the main result at hand, a Blaschke-Petkantschin formula allows us to establish new measurement functions valid when the invariant integration over flats is replaced by an invariant integration over subspaces containing a fixed subspace of lower dimension. Likewise, a stereologically adapted Crofton formula valid in the scheme of vertical sections is constructed. Only some special cases of this result have been stated explicitly before, with even the three-dimensional case yielding a new stereological formula. Here, we obtain new vertical section formulae for the surface tensors of even rank.

Determination Of Weld Thickness In Hollow Section Connection Under Local Buckling Effect

Hollow section profiles are widely used in the structural steel industry. An important point to take into consideration in such connections is the continuous transfer of internal forces from element to element. One of the measures taken to ensure this continuity is to use end plates. The connection between plates and elements is mainly provided by welds. The aim of this study is to determine an optimum weld thickness for connections subjected to local buckling of box-beam-columns under bending. Corner and circular fillet welds were used to join the designed plates with box columns and beams. Hollow section profile connections were experimentally studied in the Steel Structure Laboratory of the Department of Civil Engineering of Süleyman Demirel University. Results were used to develop numerical models. Ansys Workbench was used in numerical models to analyze the corner welds of different thicknesses and lengths depending on plate dimensions and to examine their behavior.

About Height of the Surface Air Layer by Sodar Data

Average empirical estimations of the surface air layer height in Moscow have been received by the data of long-term acoustic remote sensing of the atmosphere using MODOS Doppler sodar of METEK (Germany) production. Based on the assumption that the average conditions are close to neutral stratification, this height, as the top of the quasi-linear section of the average long-term wind velocity profile in semi-logarithmic coordinates, is 40–60 m. The wind rotation height, i. e. the height of intersection of day and night wind profiles is on average 95 meters per year. The roughness length in conditions of loose but high urban development in vicinity of Moscow State University in Moscow is 5 m. According to the criterion of the constant wind direction in the surface air layer, its height appears in the average monthly wind direction profiles over the “dead zone” of the sodar (40 m) in approximately one case out of three and usually amounts to 60 m, less often 80 or 100 m. In the rest cases, it is apparently masked by “dead zone”. The average height of the surface layer according to this approach is probably a little less than 50 m, which is close to the estimate obtained from the logarithmic distribution of wind velocity with height in this layer. The daily course of the surface air layer height is noted by the largest values in the afternoon (80–100 m in summer under conditions of prevailing unstable stratification and 60–80 m in winter) and the smallest ones (less than 40 m) in the late evening and at night in summer and from evening to noon in winter.

Numerical modeling and validation of dike-induced water flow dynamics using OpenFOAM

ABSTRACT The basic purpose of the present research is to numerically elucidate the flow around a single dike in four different geometric configurations (CN: no cylinders, C5: 5 cylinders, C10: 10 cylinders, C15: 15 cylinders), under conditions of a constant flow rate and subcritical flow. This involved substituting the impermeable dike with varying numbers of piles to validate the observed experimental flow patterns, particularly the conditions leading to reverse flow formation. OpenFOAM, an open-source algorithm, was utilized for the simulation, incorporating the volume of fluid (VOF) method. Accurately depicting the reverse flow formation with minimal numerical diffusion, a strategy involving multizone meshing and the application of mesh refinement zones was utilized. These refinements were particularly focused on the section between 1.8 m and 2.2 m within the numerical domain. The water surface profile in front section of the dike and the averaged velocity at five different locations, which were then compared with the numerical results. The numerically predicted streamwise velocity showed a percentage error ranging between 0.5% and 4.5%. The numerical results from this study are pivotal in dike design, aiming to mitigate accelerated wear during flood events and to protect both the dike head and the adjacent bank from high energy flow failures.

On the use of perforated disk inserts in a round pipe to form a gas flow of the required structure in front of an ultrasonic flow meter

Unlike conventional gas meters, ultrasonic flow meters have such advantages as contactless operation, minimal pressure loss and high accuracy. When developing ultrasonic flow meters, like any other devices, assumptions and simplifications related to the theory of ultrasonic flow meters are used. When developing such devices, researchers do not always have the necessary space to deploy such structures. Therefore, the question arises of developing devices that can replace large sections of pipelines with various turns in the role of local resistances. The paper presents some studies conducted during the development of a perforated disk capable of forming a flow profile similar to the profile after a double bend. The presented results of a study of the influence of the perforated disk geometry on the gas dynamics and flow structure. The calculations were carried out using three-dimensional computer modeling. The analysis of the influence of the hole location, their sizes and the angles of inclination of the holes relative to the disk axis on the velocity distribution and the formation of the velocity profile downstream of the disk is the purpose of this study. Scalar and vector fields of velocities downstream of the perforated disk are obtained. Velocity profiles in sections behind the disk are constructed. A comparative analysis of different designs of perforated disks is carried out. The design principles of such flow formers are indicated. The geometric factors influencing the flow structure after the former are revealed. The revealed subtleties and described design principles made it possible to develop straighteners and flow formers based on perforated disks. The final samples of disks and the results of their operation are shown

Nova-ST: Nano-patterned ultra-dense platform for spatial transcriptomics

Spatial transcriptomics workflows using barcoded capture arrays are commonly used for resolving gene expression in tissues. However, existing techniques are either limited by capture array density or are cost prohibitive for large-scale atlasing. We present Nova-ST, a dense nano-patterned spatial transcriptomics technique derived from randomly barcoded Illumina sequencing flow cells. Nova-ST enables customized, low-cost, flexible, and high-resolution spatial profiling of large tissue sections. Benchmarking on mouse brain sections demonstrates significantly higher sensitivity compared to existing methods at a reduced cost.

The effect of forming surface interference on Thin-Walled profiles during the discontinuous forming process with discrete molds

This study aims to investigate the influence of the roller dies’ characteristics of shapes on the forming results in the roller-based flexible multi-point three-dimensional stretch bending forming (FSBRD) process for thin-walled profiles, as well as the prediction of mold-induced impressions during the FSBRD process. Considering the specific contact mode, an L-shaped section profile’s flange was selected as the research object to analyze the impact of the roller dies’ slot’s geometric parameters on the product. A classification model of the contact between the profile’s flange and the roller die was established for the vertical bending process, and the maximum theoretical interference value (imax) was calculated to predict the extent of local deformation after contact. Subsequently, finite element software was used to model the process and analyze the changes in equivalent plastic strain (PEEQ) of the deformation results when using roller dies with slots of different parameters, including straight, inclined, and arc-shaped slots. The analysis results indicate that the width of the straight slot has a significant influence on the forming quality of the product, as a smaller slot width leads to larger local dimples on the product surface. Replacing the straight slot with an inclined or arc-shaped slot improves the abrupt changes in local PEEQ, resulting in reduced macroscopic local dimples. The simulation results align with the analytical model’s variation of imax. This study defined the theoretical contact angle γ and introduced the concept of the contact area and the local theoretical interference zone, providing a reasonable explanation for the observed PEEQ variations. Furthermore, based on the conclusions of the research above, modified experiments were designed, resulting in favorable forming effects. The validation of the simulation results was performed by comparing the local dimples in the contact zone of the actual experimental results.

Geology, mineralogy, geochemistry and genesis of volcano-sedimentary hosted Lake Abiyata diatomite in central main Ethiopian Rift

The Abiyata Diatomite deposit is located in the Main Ethiopian Rift, which is characterized by strong extensional tectonics. The deposit is mostly made up of diatomaceous earth, which is a sedimentary rock made up of the fossilized remnants of diatoms, which are tiny algae. Diatomite's geological, geochemical, and mineralogical features, as well as its formation, are discussed in this research. To characterize diatomite from Abiyata, chemical, mineralogical, technological, and micro paleontological examinations were conducted on samples collected from outcrops and stream sections. The XRD characteristic peaks of diatomite demonstrate that it is primarily made up of Opal A silica, however certain crystalline phases were discovered in adequate amounts. Quartz and feldspar were the predominant crystalline phases, with lesser amounts of Calcite, Cristobalite, Illite, Mordinite, Wairakite, Halloysite, Clinoaptilolite, Adularia, and Tridymite. From SEM photomicrographs diatomites are primarily formed of benthic freshwater diatom species such as Staurosirella pinnata, Staurosira construens, Pseudostaurosira brevistriata, Epithemia Sorex and surirella pinnata. Diatom species, sedimentary profile sections and mineralogical data suggest that diatomite was deposited in lacustrine-type freshwater shallow lake environment. Chemical data obtained from 10 diatomite samples show that while silica is the bodybuilding material for diatomite. i.e., Silica (SiO2), 76.9 %; Alumina (Al2O3), 3.49 %; Sodium Oxide (Na2O), 1.52 %; Potassium Oxide (K2O), 1.107 %; Iron Oxide (Fe2O3), 1.1 %; Loss on ignition (LOI) 13.7 and other oxides are below 1 %. Studies from technological properties like physical tests, chemistry, and mineralogy and micropaleontology of Abiyata diatomite suggest that calcined diatomite can be used for waste treatment processes in the filter aid industry and as filler material.

Multi-objective optimization design of rail grinding profile in Curve Section of Subway based on wear Evolution and representative worn profile

Curve rail grinding has always been one of the key points of subway maintenance and repair. The appropriate grinding can effectively reduce wear. A multi-objective optimization design method for grinding profiles in curved sections is proposed. Firstly, representative grinding profiles are selected as the initial population using the dynamic time regularization algorithm (DTW). Then, the optimal design range is determined based on wear characterization analysis, and mathematical expressions of wheel profiles are chosen as design variables to establish a parametric model. Next, the prediction model considering the evolution of wheel wear is incorporated into the multi-objective function, and objective function adaptive weight adjustment coefficient factors are introduced to establish the multi-objective optimization model for wheel profiles. The Latin hypercubic sampling method is employed to establish the RBF agent model for simulation calculation, and the optimization design of wheel profiles is carried out using the TS-NSGA-II multi-objective algorithm.

Atypical B Cells Promote Cancer Progression and Poor Response to Bacillus Calmette-Guérin in Non-Muscle Invasive Bladder Cancer.

Poor response to Bacillus Calmette-Guérin (BCG) immunotherapy remains a major barrier in the management of patients with non-muscle invasive bladder cancer (NMIBC). Multiple factors are associated with poor outcomes, including biological aging and female sex. More recently, it has emerged that a B-cell-infiltrated pretreatment immune microenvironment of NMIBC tumors can influence the response to intravesically administered BCG. The mechanisms underlying the roles of B cells in NMIBC are poorly understood. Here, we show that B-cell-dominant tertiary lymphoid structures (TLSs), a hallmark feature of the chronic mucosal immune response, are abundant and located close to the epithelial compartment in pretreatment tumors from BCG non-responders. Digital spatial proteomic profiling of whole tumor sections from male and female patients with NMIBC who underwent treatment with intravesical BCG, revealed higher expression of immune exhaustion-associated proteins within the tumor-adjacent TLSs in both responders and non-responders. Chronic local inflammation, induced by the N-butyl-N-(4-hydroxybutyl) nitrosamine carcinogen, led to TLS formation with recruitment and differentiation of the immunosuppressive atypical B-cell (ABC) subset within the bladder microenvironment, predominantly in aging female mice compared to their male counterparts. Depletion of ABCs simultaneous to BCG treatment delayed cancer progression in female mice. Our findings provide evidence indicating a role for ABCs in BCG response and will inform future development of therapies targeting the B-cell-exhaustion axis.

Influence of section profiles on flexural behavior of unsymmetrical cold formed steel sections – analytical and numerical investigation

Influence of section profiles on flexural behavior of unsymmetrical cold formed steel sections – analytical and numerical investigation

An optimal design approach for steel space frames with T-stub semi-rigid connections considering soil-structure interaction

An optimization technique for designing the steel space frame with T-stub semi-rigid connections and interaction between soil and structure is presented in this article. A three-parameter-based elastic foundation model is utilized to investigate soil-structure interactions (SSI). To enable two-way data transfer for all optimization methods, computer software was developed using C# version 17.8.6, which connects to SAP2000-OAPI version 22. Particle swarm optimization (PSO) and teaching-learning-based optimization (TLBO) are employed for optimal designs. These optimization techniques choose profile sections from a list, including 64W discrete sections from the American Institute of Steel Construction (AISC). The Load and Resistance Factor Design-American Institute of Steel Construction (LRFD-AISC) strength constraints, geometric constraints, inter-storey drift constraints, and displacement constraints are considered during optimization. The first phase entails creating optimal designs for two unique steel space frames that consider SSI but do not include T-stub semi-rigid connections. Following that, the same optimization procedures are carried out with T-stub semi-rigid connections. The parameters needed for the foundation model are obtained through soil surface displacements. Utilizing T-stub semi-rigid connections while considering the interaction between the structure and the soil produces increased structural weight.