Exact Shape Research Articles

Pre-experiment of 70 MeV H - cyclotron for producing ISOL RI beam.

The Rare Isotope Science Project (RISP) is currently constructing equipment and facilities for the Rare Isotope Accelerator complex for ON-line experiments (RAON). The first experiment being conducted involves the acceleration of a proton to 70MeV using a cyclotron, which is then delivered to a SiC target to generate a radioactive isotope beam in the ISOL system. However, before conducting this experiment, a preliminary experiment was performed to confirm the exact location and shape of the proton beam to prevent loss of the proton beam. The pre-experiment involved configuring a faraday cup, wire grid scanner, collimator, and slit inside the proton beam diagnostic module to understand the characteristics of the proton beam at the target position. The beam current ranged from 1 μA to 1.5 μA, and the beam size was confirmed to be within the 2×2cm 2 slit size.

ПРЕОБРАЗОВАНИЕ СХЕМЫ ФОРМООБРАЗОВАНИЯ ОБТЯЖКОЙ НА ПРИНЦИПАХ СИММЕТРИИ

We assume that the concept of symmetry plays an important role in improving the theory and practice of the forming process by covering load-bearing thin-sheet shells of double curvature, which guarantees the production of contour-forming parts of the skin of modern aircraft with an exact geometric shape and minimal variation in thickness. To understand our assumption, it is necessary to remember that the complexity of the theory of plastic shells lies in the geometric and physical nonlinearity and the need to take into account shear stresses and deformations along the surface of the shell and its variability in curvature, therefore there is still no unified approach to the analysis of the formative processes of covering from sheet material. This assumption applies only to thin-sheet shells of double curvature, providing a different isometric position (curved surfaces one on top of the other) of the open surface as a whole, and not closed like a sphere. Therefore, the process of shaping a sheet blank into a shell part of an aircraft has some form of symmetry with respect to a given set of surface transformations, unless certain properties or relationships, the so-called invariants of the set of transformations, change when they are performed.

A multiscale analytical-numerical method for the coupled heat and mass transfer in the extended meniscus region considering thin-film evaporation in microchannels

A Computational Fluid Dynamics (CFD) framework is established to investigate the microscale transport phenomena in the evaporating extended meniscus region formed in rectangular microchannels. A wide range of microchannel widths (W = 1 to 250 µm) and wall superheats (ΔT = 0.01 to 5.0 K) are considered. Prior to performing CFD simulations, it is first necessary to employ thin-film evaporation modeling based on an augmented Young–Laplace model and kinetic-theory based model for the evaporating mass flux across curved surfaces to find the exact shape of the liquid-vapor interface along with disjoining and capillary pressure distributions. Two widely-used methods for the determination of boundary conditions (BCs) at the beginning of the thin-film region (i.e., setting δ0″ = 0 and finding δ0′ by the far-field BC or setting δ0′ = 0 and finding δ0″ by the far-field BC), where δ is film thickness, are thoroughly examined and the first approach is recommended because of its better convergence and ease of implementation in the thin-film evaporation model. Then, the two-dimensional domain of the extended meniscus is generated and discretized to simulate the evaporating liquid flow through the UDF programming in ANSYS Fluent. The developed framework is shown to be a simple yet powerful and practical method for accurately predicting the evaporation mass and heat fluxes from extended menisci in microchannels. The CFD simulation results indicate that the previous one-dimensional models which represent the state of the art in the literature in the field are not able to predict the rate of evaporative heat transfer from the extended meniscus in microchannels with an acceptable degree of accuracy. Based on the CFD simulations results, a multiple regression analysis is employed to establish several simple thermal resistance correlations. The correlations can be straightforwardly integrated into macroscale mathematical models of micro and miniature heat pipes for analyzing their thermal characteristics.

Experimental and theoretical basic research on sound absorption characteristics of foam materials with and without membrane

A basic study was conducted to theoretically estimate the acoustic properties of a sound-absorbing foam material. Generally, the lattice of sound-absorbing foam materials contains membranes. Herein, for simplicity, a mathematical model was constructed assuming a cubic frame structure as the basic frame structure of the foam, which included a membrane. Accordingly, the sound absorption coefficient was obtained and compared with the experimental results. In the mathematical model, the clearance in the frame structure (with membrane) was divided into elements and was approximated as a clearance surrounded by two parallel planes, considering the exact shape of each element. Herein, the characteristic impedance and propagation constant of the approximated clearance were obtained and treated as a one-dimensional transfer matrix, and the sound absorption coefficient was calculated using the transfer matrix method. For the experiments, the samples were fabricated using a 3D printer and the sound absorption coefficient was measured using a two-microphone impedance tube. Overall, the experimental and theoretical results exhibited similar trends.

Real-time identification of small anomalies from scattering matrix without background information

Several researches have confirmed the possibility of localizing small anomalies via Kirchhoff migration (KM); however, when the background information is unknown, small anomalies cannot be satisfactorily retrieved. This fact can be examined through the simulation results; however, related theoretical result to explain the reason of such phenomenon has not yet been investigated. In this contribution, we show that the imaging function of the KM can be expressed by an infinite series of the Bessel function of the first kind, material properties, and antenna arrangement, and applied alternative value of the background wavenumber. Based on the theoretical result, we explain why the exact location and shape of anomalies cannot be retrieved. The simulation results with synthetic data exhibited to support the theoretical result.

The hypothesis of the shape of the permafrost in Hornsund, Spitsbergen and the potential impact of its degradation on the Arctic

The areas covered by permafrost in the polar regions are vulnerable to rapid changes in the current climate. The well-studied near-surface active layer and permafrost zone are in contrast to the unknown exact shape of the bottom permafrost boundary. Therefore, the entire shape of permafrost between the upper and lower boundaries is not identified with sufficient accuracy. Since most of the factors affecting deep cryotic structures are subsurface in nature, their evolution in deeper layers is also relatively unclear. Here, we propose a hypothesis based on the results of geophysical studies regarding the shape of the permafrost in the coastal area of Svalbard, Southern Spitsbergen. In the article, we emphasize the importance of recognizing not only the uppermost active layer but also the bottom boundary of permafrost along with its transition zone, due to the underestimated potential role of its continuity in observing climate change. The lower permafrost boundary is estimated to range from 70 m below the surface in areas close to the shore to 180 m inland, while a continuous layer of an entirely frozen matrix can be identified with a thickness between 40 m and 100 m. We also hypothesized the presence of the possible subsea permafrost in the Hornsund. The influence of seawater intrusions, isostatic uplift of deglaciated areas, and surface-related processes that affect permafrost evolution may lead to extensive changes in the hydrology and geology of the polar regions in the future. For all these reasons, monitoring, geophysical imaging and understanding the characteristics and evolution of deep permafrost structures requires global attention and scientific efforts.

BladeDISC: Optimizing Dynamic Shape Machine Learning Workloads via Compiler Approach

Compiler optimization plays an increasingly important role to boost the performance of machine learning models for data processing and management. With increasingly complex data, the dynamic tensor shape phenomenon emerges for ML models. However, existing ML compilers either can only handle static shape models or expose a series of performance problems for both operator fusion optimization and code generation in dynamic shape scenes. This paper tackles the main challenges of dynamic shape optimization: the fusion optimization without shape value, and code generation supporting arbitrary shapes. To tackle the fundamental challenge of the absence of shape values, it systematically abstracts and excavates the shape information and designs a cross-level symbolic shape representation. With the insight that what fusion optimization relies upon is tensor shape relationships between adjacent operators rather than exact shape values, it proposes the dynamic shape fusion approach based on shape information propagation. To generate code that adapts to arbitrary shapes efficiently, it proposes a compile-time and runtime combined code generation approach. Finally, it presents a complete optimization pipeline for dynamic shape models and implements an industrial-grade ML compiler, named BladeDISC. The extensive evaluation demonstrates that BladeDISC outperforms PyTorch, TorchScript, TVM, ONNX Runtime, XLA, Torch Inductor (dynamic shape), and TensorRT by up to 6.95×, 6.25×, 4.08×, 2.04×, 2.06×, 7.92×, and 4.16× (3.54×, 3.12×, 1.95×, 1.47×, 1.24×, 2.93×, and 1.46× on average) in terms of end-to-end inference speedup on the A10 and T4 GPU, respectively. BladeDISC's source code is publicly available at https://github.com/alibaba/BladeDISC.

Decision criteria in signal detection model are not based on the objective likelihood ratio.

How people set decision criteria in signal detection model is an important research question. The likelihood ratio (LR) theory, which is one of the most influential theories about criteria setting, typically assumes that (a) decisions are based on the objective LR of the signal and noise distributions, and (b) LR criteria do not change across tasks with various difficulty levels. However, it is often questioned whether people are really able to know the exact shape of signal and noise distributions, and compute the objective LR accordingly. Here we suggest whether decision criteria are set based on objective LR can be tested in two-condition experiments with different difficulty levels across conditions. We then asked participants in three empirical experiments to perform two-condition perceptual or memory tasks, and give their answer using confidence rating scale. Results revealed that the two assumptions of LR theory contradicted with each other: if we assumed decision criteria were based on objective LR, then the estimated LR criteria differed across difficulty levels, and fanned out as task difficulty decreased. We suggest people might inaccurately estimate the LR in signal detection tasks, and several possible explanations for the distortion of LR are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Residual shape adaptive dense-nested Unet: Redesign the long lateral skip connections for metal surface tiny defect inspection

The state-of-the-art metal surface defect inspection methods have two problems: (1) they are sensitive to tiny defects because of their extreme small sizes, and (2) they cannot accurately locate the random appeared defects whose semantic relationship with the background context is weak. To solve these problems, Residual Shape Adaptive Dense-nested Unet, a pixel-based defect inspection method is proposed, to obtain the exact shape and location of the defect, by (1) assembling different depth Unet branches with dense skip connections as the feature extractor to combine multi-semantic level visual features; (2) adding Residual Shape Adaptive modules on the dense skip connections to help the model locate the defect regions; and (3) introducing the multi-branch training method which enables model pruning to reduce redundant parameters and accelerate the inspection speed. Experiments are conducted and demonstrated that the Residual Shape Adaptive Dense-nested Unet achieves the best performance among the state-of-the-art defect inspection methods.

Shannon Entropy of Ramsey Graphs with up to Six Vertices.

Shannon entropy quantifying bi-colored Ramsey complete graphs is introduced and calculated for complete graphs containing up to six vertices. Complete graphs in which vertices are connected with two types of links, labeled as α-links and β-links, are considered. Shannon entropy is introduced according to the classical Shannon formula considering the fractions of monochromatic convex α-colored polygons with n α-sides or edges, and the fraction of monochromatic β-colored convex polygons with m β-sides in the given complete graph. The introduced Shannon entropy is insensitive to the exact shape of the polygons, but it is sensitive to the distribution of monochromatic polygons in a given complete graph. The introduced Shannon entropies Sα and Sβ are interpreted as follows: Sα is interpreted as an average uncertainty to find the green α-polygon in the given graph; Sβ is, in turn, an average uncertainty to find the red β-polygon in the same graph. The re-shaping of the Ramsey theorem in terms of the Shannon entropy is suggested. Generalization for multi-colored complete graphs is proposed. Various measures quantifying the Shannon entropy of the entire complete bi-colored graphs are suggested. Physical interpretations of the suggested Shannon entropies are discussed.

Association between urinary methylparaben level and bone mineral density in children and adolescents aged 8-19 years.

Previous epidemiological study has explored a positive association between methylparaben (Mep) and bone mineral density (BMD) in adults. Evidence linking Mep and BMD in children and adolescents is very limited. This study examined the association between Mep and BMD in children and adolescents aged 8-19 years. In this cross-sectional study, 1830 children and adolescents aged 8-19 years from NHANES 2011-2016 were analyzed. Mep was ln-transformed for analysis of the skewed distribution. Multiple linear regression analyses were performed to evaluate Mep's association with BMD (containing total BMD, trunk bone BMD, pelvis BMD, lumbar spine BMD, and thoracic spine BMD). Moreover, a generalized additive model (GAM) and a fitted smoothing curve (penalized spline method) were conducted to explore the exact shape of curve between them. In the fully adjusted model, ln-transformed Mep and BMD showed an independent and positive association (total BMD (β = 0.003, 95% CI (0.001, 0.005), P = 0.01), trunk bone BMD (β = 0.002, 95% CI (0.000, 0.005), P = 0.04), pelvis BMD (β = 0.004, 95% CI (0.001, 0.008), P = 0.02), lumbar spine BMD (β = 0.005, 95% CI (0.001, 0.008), P = 0.01), thoracic spine BMD (β = 0.003, 95% CI (0.001, 0.005), P = 0.02)) and a linear association. Subgroup analysis showed positive association between ln-transformed Mep and BMD. Furthermore, the positive association was significant in females and children aged 12-19 years (P for trend < 0.05). This study is the first study to find evidence demonstrating that exposure to Mep may be positively associated with BMD in children and adolescents aged 8-19 years. Validation of our findings will need further research.

Delamination Detection and Localization in Vibrating Composite Plates and Shells Using the Inverse Finite Element Method.

Delamination damage is one of the most critical damage modes of composite materials. It takes place through the thickness of the laminated composites and does not show subtle surface effects. In the present study, a delamination detection approach based on equivalent von Mises strains is demonstrated for vibrating laminated (i.e., unidirectional fabric) composite plates. In this context, the governing relations of the inverse finite element method were recast according to the refined zigzag theory. Using the in situ strain measurements obtained from the surface and through the thickness of the composite shell, the inverse analysis was performed, and the strain field of the composite shell was reconstructed. The implementation of the proposed methodology is demonstrated for two numerical case studies associated with the harmonic and random vibrations of composite shells. The findings of this study show that the present damage detection method is capable of real-time monitoring of damage and providing information about the exact location, shape, and extent of the delamination damage in the vibrating composite plate. Finally, the robustness of the proposed method in response to resonance and extreme load variations is shown.

A Numerical Study on the Ballistic Performance of Projectiles Formed by Shaped Charge

Abstract In this work, a numerical analysis of shaped charge impact process is conducted to investigate the jet formation process and its penetration performance on metal targets. Numerical results are compared with experimental data from published literature for liners made up of copper and iron. Conical and bowl-shaped liner geometries are simulated with various configurations to observe their effects on projectile shape and penetration capability using the finite element (FE) method. The exact shape of the explosively formed projectile at the onset of impact is modeled as a rigid 3D body to simulate the penetration process. #45 and Armox 500T steels are used as the target materials, and the material behavior and failure mechanisms are modeled using the Johnson–Cook (JC) plasticity and damage models. In addition to the FE method, smoothed particle hydrodynamics (SPH) is utilized as well to evaluate its capacity in predicting the failure behavior of the metal targets. It is concluded that the FE method outperforms the SPH method at predicting failure modes, while SPH can still be used to predict residual velocity and hole diameters. Armox 500T demonstrates a higher impact resistance compared to #45 steel. Liner geometry is found to significantly affect penetration performance. Sharper and thinner projectiles formed from liners with small cone angles are shown to be highly efficient in penetrating through armor steel targets.

Design and Development of Orbital Riveting Machine

Orbital Spin riveting is a relatively new technology for bearing locking in which parts are joined by specific movement of tools. Special incremental motion enables smaller contact area between tool and cage and therefore, lower forming load and friction. Hence, orbital spin riveting makes it possible to join a desired part in lower forming force in the operation, whereas in conventional locking more force would be required. The angle of the riveting tool held in the riveting head plays a significant role in the reduction in forming force, whereas the table motion will determine the accurate positioning of the rivet in to tool profile, resulting into exact shape and size of rivet head formed. This project presents a brief overview of Design and Development of Orbital Riveting machine for Bearing Assembly which leads to improve the product quality and its Productivity. Keywords: Orbital Riveting, Design, Development, Cost TRIZ, SPM, Productivity

Nasal cavity perforation by implant fixtures: case series with emphasis on panoramic imaging of nasal cavity extending posteriorly

The nasal cavity is an important landmark when considering implant insertion into the anterior region of the maxillary arch. The perforation of implants into the nasal cavity may cause complications, such as implant migration, inflammation, or changes in nasal airflow; thus, precise assessment of the nasal cavity is mandatory.Three cases of nasal cavity perforation by dental implants are presented, including one case of implant fixture migration into the nasal cavity. On panoramic radiographs of the patients, the following common features were observed: the horizontal radiopaque line of the hard palate was observed to be inferior to or similar to that of the antral floor and the bone between the lateral wall of the nasal cavity and the medial wall of the maxillary sinus was emphasized in a triangular shape.When the maxillary sinus is small and alveolar bone resorption is severe, panoramic evaluation may cause overestimation of the available residual bone, particularly in the maxillary canine/premolar region. Therefore, the residual bone should be reevaluated three-dimensionally to measure the exact bony shape and volume.

The Temporal and Spatial Evolution of Magnetohydrodynamic Wave Modes in Sunspots

Through their lifetime, sunspots undergo a change in their area and shape and, as they decay, they fragment into smaller structures. Here, for the first time we analyze the spatial structure of the magnetohydrodynamic (MHD) slow-body and fast-surface modes in the observed umbrae as their cross-sectional shape changes. The proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) techniques were used to analyze 3 and 6 hr Solar Dynamics Observatory/Helioseismic and Magnetic Imager time series of Doppler velocities at the photospheric level of approximately circular and elliptically shaped sunspots. Each time series was divided into equal time intervals to evidence the change in the shape of the sunspots. To identify the physical wave modes, the POD/DMD modes were cross-correlated with a slow-body mode model using the exact shape of the umbra, whereas the shape obtained by applying a threshold level of the mean intensity for every time interval. Our results show that the spatial structure of MHD modes are affected, even by apparently small changes in the umbral shape, especially in the case of the higher-order modes. For the data sets used in our study, the optimal time intervals to consider the influence of the change in the shape on the observed MHD modes is 37–60 minutes. The choice of these intervals is crucial to properly quantify the energy contribution of each wave mode to the power spectrum.

Longitudinal developmental trajectories of functional connectivity reveal regional distribution of distinct age effects in infancy.

Prior work has shown that different functional brain networks exhibit different maturation rates, but little is known about whether and how different brain areas may differ in the exact shape of longitudinal functional connectivity growth trajectories during infancy. We used resting-state functional magnetic resonance imaging (fMRI) during natural sleep to characterize developmental trajectories of different regions using a longitudinal cohort of infants at 3weeks (neonate), 1year, and 2years of age (n = 90; all with usable data at three time points). A novel whole brain heatmap analysis was performed with four mixed-effect models to determine the best fit of age-related changes for each functional connection: (i) growth effects: positive-linear-age, (ii) emergent effects: positive-log-age, (iii) pruning effects: negative-quadratic-age, and (iv) transient effects: positive-quadratic-age. Our results revealed that emergent (logarithmic) effects dominated developmental trajectory patterns, but significant pruning and transient effects were also observed, particularly in connections centered on inferior frontal and anterior cingulate areas that support social learning and conflict monitoring. Overall, unique global distribution patterns were observed for each growth model indicating that developmental trajectories for different connections are heterogeneous. All models showed significant effects concentrated in association areas, highlighting the dominance of higher-order social/cognitive development during the first 2 years of life.

Voronoi Natural Neighbours Tessellation: An interpolation and grid agnostic approach to forensic soil provenancing

Recently there has been an increase of work dedicated to developing a more objective soil provenancing capability. Notwithstanding the significant progress made, the presented provenancing techniques have predominately been based upon interpolation grids, generated from often arbitrary decisions of the user (e.g., grid cell size, grid placement, interpolation model, etc.). To address the acknowledged reproducibility issues, this paper introduces a spatial modelling technique based upon Voronoi Tessellations that is free from arbitrary user decisions. Termed herein as Voronoi Natural Neighbours Tessellation (VNNT), the proposed approach segments the survey area into many “honeycomb-like” polygons. Of which, the exact number, shape, location, and orientation of polygons are inherently dependent upon the original density of input sampling points from the survey, not a user’s subjective decision.Utilising compositional geochemistry data from a fit-for-purpose topsoil survey and eleven “blind” soil samples from Canberra, Australia, we compare this proposed VNNT approach against a simpler Voronoi Tessellation, and a previously presented 500 m × 500 m grid following a modified and upscaled Natural Neighbour interpolation. Aside from also being computationally less intensive, our results indicated the proposed VNNT approach regularly yielded at least equal, or often more accurate provenance predictions than that of the gridded Natural Neighbour interpolation. Importantly, the delineation of individual polygons is fundamentally dependent upon the survey’s real sampling design, and most truthfully reflects the underlying sampling density, and associated uncertainties. Consequently, the VNNT approach is significantly less susceptible to expert bias as a result of subjective decision-making and “fine-tuning” of interpolation parameters.

New wormhole model with quasi-periodic oscillations exhibiting conformal motion in gravity

This analysis explores the new wormhole (WH) solution in the background of teleparallel gravity with minimal matter coupling. To complete this study, we consider the conformal symmetry with non-zero Killing vectors. The exact shape function is computed by considering the linear equation of state with the phantom regime. The energy conditions are investigated for the calculated shape function with the equation of state parameter. The presence of exotic matter is confirmed due to the violation of the null energy condition. The current study also explores the physical properties of the epicyclic frequencies with quasi-periodic oscillations. In the astrophysical, epicyclic frequencies are extensively employed to explore the self-gravitating system. It is concluded that a stable WH solution is acceptable for WH geometry.

Nonlinear finite element Analysis of laterally loaded piles in Layered Soils

This work is based on Winkler’s theory to analyze laterally loaded single piles using the finite element method. Soil nonlinearity is taken into account via nonlinear springs “p-y” curves. Exact element displacement shape functions and stiffness matrix are used for the element in the case of linear Winkler’s modulus of subgrade reaction. In the nonlinear stage, an averaging technique for the element secant Winkler modulus is used to calculate the shape functions and stiffness matrix. An iterative technique is used to take into account the non-linearity of the soil. Few elements are required to simulate the pile efficiently. Unlike other analytical methods, the current method can be used to analyze piles with any load-transfer curves with arbitrary variation with depth.