bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Curvature on Dynamic Response of Dyneema Composite Panel Under Extreme Loading: A Numerical Study
Authors: Kumar Vivek , Sankrityayan Rohit , Chawla Anoop , Dubey Devendra K. 
Published: October 2023

Abstract
Ultra-molecular weight polyethylene (UHMWPE) composites are the first choice for protective systems due to their inherent characteristics. These composites are widely used in bulletproof jackets as ceramic backing and enhanced combat helmets (ECH). While the ballistic performance of UHMWPE composites is well-researched, their response to blasts has not been extensively studied. Numerical analysis is used to evaluate the impact of the geometric curvature of Dyneema HB26 composite panels when exposed to extreme loading conditions. This analysis helps to determine the behavior and performance of the composite panels under these conditions and provides insight into their suitability for use in such applications. The results of the analysis can be used to optimize the design of the composite panels and ensure that they meet the necessary safety and performance requirements for the specific application. Simulations were carried out using the Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) method in the LS-Dyna software. A parametric study was conducted for varying curvatures of the composite panel with four different thicknesses using a validated finite element framework. The outcomes were analyzed and compared for mid-point deflection and number of damaged layers. This study helps to improve the performance of composite panels in critical defense protection systems using appropriate geometric curvature.
Dynamic Aeroelastic Response of Camber Morphing Aircraft
Authors: Soneda Kensuke , Tsushima Natsuki , Yokozeki Tomohiro , Imamura Taro 
Published: October 2023

Abstract
Morphing technology has been intensively studied in the last decades. Camber morphing is one of the most popular and effective types of morphing, and its aerodynamic advantages have been demonstrated. Although its aeroelasticity has been studied in previous research, the coupling between its aeroelasticity and the flight dynamics of the overall aircraft has not been investigated well. This study aims to understand the influence of the aeroelasticity of morphing control surfaces on the flight dynamics of the aircraft. For this objective, an aeroelastic flight simulation framework that can consider camber morphing is developed. For the structural model, finite shell elements are used to capture the behavior of the camber morphing structures. For aerodynamics, an unsteady vortex lattice method is used to estimate the unsteady aerodynamic loads efficiently. A rigid-body flight dynamics is coupled with the structural and aerodynamic model to construct the aeroelastic flight simulation framework. The flight motions of the aircraft with morphing elevators are simulated under open-loop control. The results demonstrated that the aeroelastic response of morphing elevators differs depending on the stiffness of the morphing structure. It is also shown that this leads to the different gusts that the aircraft with morphing elevator experiences severe altitude changes.
High Resolution Experimental Study of Damage Initiation in Cross-Ply Laminate Using Digital Volume Correlation
Authors: Rojas Sanchez J. Fernando , Waas Anthony M. 
Published: October 2023

Abstract
The damage initiation mechanisms of a single edge notched cross-ply laminate are studied using a Digital Volume Correlation (DVC) analysis. The experimental results are used to verify an SD2M [1] model of the same problem. Using material properties found in the literature, the initial stiffness and the non-linearity of the force-strain curve were verified. The predicted crack density evolution of the model resembled closely that observed from Digital Image Correlation results. Although the ultimate load predicted by the model was within the experimental spread, it was non-conservative relative to the average. Another discrepancy between the model and experimental data was observed in the order in which the damage modes initiate and the points in the load-strain curve at which they happen. The procedure followed in this study demonstrates the potential of the DVC data collected for model verification.
A Refined Rotordynamics Model Analysis for Variable Thickness Rotors and Rotating Disks
Authors: Rubino Andrea , Cinefra Maria , Filippi Matteo 
Published: October 2023

Abstract
In industrial sector, rotating disks are widely used for engineering applications, for instance turbojet engines or steam turbines, and they are usually designed with non-uniform thickness in radial direction in order to improve stress and displacement fields and to reduce weight and rotational inertia. In this paper, a refined Finite Element Method (FEM) based on the Carrera Unified Formulation (CUF) is extended to evaluate the vibration characteristics of rotors with variable thickness. Using Lagrange-like polynomial Expansions (LE), the Node-Dependent-Kinematics (NDK) approach of this model is exploited: the geometry of the rotor is discretized into a finite number of 1D beam elements along the axis where the LE elements allow to develop refined displacement theories over the cross section of the beam; in addition, the NDK approach allows to discretize the rotating disks in a smooth way, accounting for the variable thickness of the considered elements. The governing equations are derived using the Hamilton’s Principle and solved through the Finite Element Method combined with the 1D CUF beam theory. Different numerical examples are investigated to illustrate the capabilities of the presented technique. The results represent the starting point to study the rotordynamics model, including the rotating effects such as the geometrical stiffening, the spin softening and the Coriolis contribution.
Predicting Stress in Structures Using Convolutional Neural Networks: the Case for 2D Plates
Authors: Truhn Ryan , Masoumi Masoud 
Published: October 2023

Abstract
Aeronautical structures are subjected to various loadings and damage initiators, such as bird strikes, which can reduce their lifespan. High internal stresses can contribute to potential failures. Therefore, high-fidelity modeling methods, such as finite element analysis (FEA), are used to study these structures under various loading conditions to design more resilient systems. However, these methods are computationally expensive and time-consuming, especially for large projects. Reliable, efficient techniques that can analyze the performance of these structures can improve the design process and reduce the risk of incidents. As an attempt to reduce analysis time, we propose using deep neural network models, specifically an encoder-decoder based convolutional neural network (CNN), to predict stress distribution in a structure based on geometry, external loadings, and boundary conditions. To implement this technique, we study stress distribution in 2D plates with different geometries and loading conditions using a Python script and FEA software. The script creates plates with unique conditions and runs FEA to obtain stress data, which is used to train and test the CNN model. The results of our analysis show good accuracy for stress field predictions and offer a reliable, fast technique for analyzing engineering structures. This method can be modified to study stress fields under various loading conditions for more complex structures in a fraction of the time it would take the FEA software to run the required simulations.
Investigations on Natural Frequency Shifts of a Cantilever Beam With a Spherical Void Defect
Authors: West Jeremy , Folden Trevor , O’Connor Dennis 
Published: October 2023

Abstract
Additive manufacturing methods, specifically metal 3D printing techniques are being used to allow intricacies of design never-before possible with traditional machining methods. Nevertheless, while a great deal of research has investigated the characteristics of cracks and defects in traditionally manufactured parts, far less work has examined the dynamic signatures associated with defects common to metal 3D printed parts. This paper investigates the dynamic signatures correlated with internal ablations in an additively manufactured, metal, cantilever beam. A mathematical model is developed to define the second area moment of a rectangular cantilever beam in the presence of a spherical void. Through the direct integration method, an explicit solution for stiffness is determined for a defected beam.
Architected Cellular Materials for Aerospace Components Design and Manufacturing
Authors: Rastegarzadeh Sina , Huang Jida , Wang Jun 
Published: October 2023

Abstract
The design of high-performance, lightweight materials has always been challenging in aerospace structural design (e.g., aircraft ailerons, flaps, and rudders). Sandwich panel composites with lattice cores are widely used in aerospace applications. This paper presents an inverse design optimization framework for sandwich structures with implicitly represented architected cellular unit cells. Specifically, cellular materials are implicitly represented (described by functions) as building blocks in the core structure design. A core topology optimization problem is formulated based on functionalities (compliance and thermal conductivity) in this paper. Lastly, the optimized delicate design is directly converted into digital slices for additive manufacturing, which avoids memory-expensive solid model conversion. The proposed design framework is validated in two aerospace design case studies. Experimental results demonstrate the effectiveness of the proposed optimization algorithm and STL-free scheme for additive manufacturing.
Fabricating Machine Elements Using Hydrogel-Infused Additive Manufacturing (HIAM)
Authors: Saigal Anil , Velling Seneca Jackson , Dhawan Akash , Azcona Baez Maria , Nocum Miguel , R. Greer Julia 
Published: October 2023

Abstract
Additive manufacturing (AM) of metals can enable rapid development of functional parts of complex geometry, with potential applications in the aerospace, automotive, and biomedical fields [1–3]. Typical metal additive manufacturing techniques are based on expensive laser melting or sintering processes which are often highly anisotropic, limiting the development and use of these methods. Furthermore, few additive manufacturing techniques focus on high temperature materials, ceramics, and fabrication of machine elements. The recent introduction of Hydrogel-Infusion Additive Manufacturing (HIAM) may reduce some of these barriers, enabling potential applications in high performance metal and ceramic devices and components. The HIAM process involves 3D printing a polyethylene oxide (PEO) photo-resin using vat polymerization, immersing the polymer in a metal salt solution which allows ionized metal cations to bond to the polymer backbone, followed by calcination to combust the polymer leaving a metal oxide that takes the same functional structure as the original polymer. Finally, the metal oxide is reduced using a forming gas (95% N2/5% H2) to give a metal product that maintains a scaled-down version of the complex as-printed architecture. This technique enables architected features with microscale resolution by use of a single photoresin simply by varying post-processing conditions. As a first step in the fabrication of machine elements and devices, this paper outlines an attempt to fabricate springs made from silver metal via HIAM. Silver nitrate is infused into an additively manufactured polymer spring structure. Based on the relative differences in the standard free energy of the oxides, Silver Oxide (AgO) is readily reduced to metallic silver under a single thermal processing step: calcination/reduction at 500°C without the need for forming gas. A variety of analytical techniques confirm HIAM processing obeys chemical kinetics of single-step calcination and reduction in accordance with literature and results in fabricated components of low microstrain (8.40E−7 ± 2.78E−9) crystalline silver with average crystallite size of 514.95 ± 5.32 Å and lattice parameter of 4.09 ± 5.23E−5 Å. Thermal analyses such as Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) elucidate the mass loss and reactions that occur during the furnace processing. Springs were subjected to quasi-static and cyclic loading using a Dynamic Mechanical Analyzer (DMA). A range of ∼2–20 N/mm stiffness was measured in unloading for different coil diameters and produced springs show consistency of part stiffness following compaction under cyclic loading.
Nonlinear Response of Contact Interface With Nanoscale Fractal Roughness Under Harmonic Excitation for Jointed Structures
Authors: Sun Yunyun , Wu Bing , Wu Shijing , Li Hongguang 
Published: October 2023

Abstract
Rough interfaces inevitably exist between precision mechanical parts for aerospace jointed structures. The roughness of the contact surface varies from microscale to nanoscale and exhibits self-similarity characteristics. Since the computational time of molecular dynamics (MD) simulation is generally less than microseconds, the steady-state vibration response of contact interfaces with nanoscale roughness is hard to obtain. Considering the nanoscale roughness of the surface morphology, the present work provides a theoretical method for analyzing the steady-state vibration of contact interface under harmonic excitation by combining the molecular dynamics simulation with the multi-scale method. The surface morphology is constructed from the atomic level, and the contact model of the nanoscale roughness interface is established. The fitting relationship between the normal contact force and the equivalent displacement is obtained. Accordingly, the mathematical equation of the contact vibration of the rough interface is derived. Variation of the natural frequency with the initial displacement is studied, and the amplitude-frequency response of the rough contact interface in steady-state vibration is revealed. Results show that jointed structures with nanoscale rough morphology exhibit nonlinearity in contact behaviors. The natural frequency decreases as the initial deflections deviate from the static equilibrium position. The amplitude jump phenomenon of the rough contact interface is observed under harmonic excitation, and a rougher interface corresponds to a stronger nonlinearity of amplitude-frequency dependence. Reducing the fractal roughness or increasing the fractal dimension of the contact interface may narrow down the excitation frequency range of the main resonance.
A Review of Analytical Models for Determining the Behavior of Metallic Tubular Structures Submitted to Axial Crushing
Authors: Anand Shreyas , Alderliesten René , Castro Saullo Giovani Pereira 
Published: October 2023

Abstract
This paper reviews analytical models proposed by Abramowicz et al.[1, 2] and Stefan et al.[3] for the axial crushing of metallic tubular structures with square and circular cross-sections. First, a database of experiments for square and circular tubes was created based on the literature. Subsequently, the predictions obtained using these analytical models were compared against the database of experiments to determine the accuracy of these analytical models. The database of experiments was also compared against some results generated using Finite-Element Method (FEM). Furthermore, the sensitivity of the analytical models to various material and geometrical parameters was studied to determine the influence of these parameters on the mean crushing force.
Both models were found to be highly sensitive to the thickness of the tubular structures. It was observed that the models proposed by Abramowicz et al.[1, 2] showed better agreement with experimental results, although an over-prediction was observed for square tubular structures made of materials with a significant difference between the values of yield and ultimate stress. The model proposed by Stefan et al.[3] slightly over-predicted for square tubes and showed reasonable accuracy for circular tubes.
How Societal Forces of Change Are Transforming Youth Physical Activity Promotion in North America
Authors: Szeszulski Jacob , Faro Jamie M. , Joseph Rodney P. , Lanza Kevin , Lévesque Lucie , Monroe Courtney M. , Pérez-Paredes Elsa A. , Soltero Erica G. , Lee Rebecca E. 
Published: October 2023

Background: Climate change, increasing recognition of institutionalized discrimination, and the COVID-19 pandemic are large-scale, societal events (ie, forces of change) that affect the timing, settings, and modes of youth physical activity. Despite the impact that forces of change have on youth physical activity and physical activity environments, few studies consider how they affect physical activity promotion. Methods: The authors use 2 established frameworks, the ecological model of physical activity and the youth physical activity timing, how, and setting framework, to highlight changes in physical activity patterns of youth in North America that have resulted from contemporary forces of change. Results: North American countries—Canada, Mexico, and the United States—have faced similar but contextually different challenges for promoting physical activity in response to climate change, increasing recognition of institutionalized discrimination, and the COVID-19 pandemic. Innovative applications of implementation science, digital health technologies, and community-based participatory research methodologies may be practical for increasing and sustaining youth physical activity in response to these forces of change. Conclusions: Thoughtful synthesis of existing physical activity frameworks can help to guide the design and evaluation of new and existing physical activity initiatives. Researchers, practitioners, and policymakers are encouraged to carefully consider the intended and unintended consequences of actions designed to respond to forces of change.
Whole-genome sequences of
Bipolaris bicolor
,
Curvularia hawaiiensis
,
Curvularia spicifera
, and
Exserohilum rostratum
isolated from rice in Burkina Faso, France, Mali, and Pakistan
Authors: Kaboré Kouka Hilaire , Kassankogno Abalo Itolou , Adreit Henri , Ravel Sebastien , Charriat Florian , Diagne Diariatou , Lebrun Marc-Henri , Tharreau Didier 
Published: October 2023

ABSTRACT

Different fungal species of the
Pleosporaceae
family infect rice, causing similar symptoms. Reference genomic sequences are useful tools to study the evolution of these species and to develop accurate molecular diagnostic tools. Here, we report the complete genome sequences of
Bipolaris bicolor
,
Curvularia hawaiiensis
,
Curvularia spicifera,
and
Exserohilum rostratum
.
Inference and forecasting phase shift regime of COVID-19 sub-lineages with a Markov-switching model
Authors: Noh Eul , Hong Jinwook , Yoo Joonkyung , Jung Jaehun 
Published: October 2023

ABSTRACT
The occurrences and domination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are still crucial factors for determining the coronavirus disease 19 (COVID-19) policies. We collected weekly Phylogenetic Assignment of Named Global Outbreak sub-lineages, naming genetically distinct lineages of SARS-CoV-2, including variants of concern, in the United Kingdom, South Africa, South Korea, Denmark, Germany, the United States, and worldwide. This study included 12,296,756 samples of the max share of the sub-lineages from the 33rd week of 2020 to the 40th week of 2022. This study conducted a two-state Markov-switching model to estimate the probability of the phase shift state and predicted the probability of each regime with the Hamilton filter and Kim’s smoothing algorithm. We discovered different weekly patterns based on dominant SARS-CoV-2 variants in target area. Due to differences in containment policies and outbreak waves, we observed a time lag in dominant variants in these countries. Using the inferred probability of the phase shift regime for forecasting, it showed significant probabilities that the stable phase will still be stable in the next week. It also showed significant probabilities that the unstable phase will still be unstable in the next week. Our findings present the probability of observing the phase shift regime each week. Until a new SARS-CoV-2 variant occurs, the regime tended to stay with a low probability of phase shift regime. When a new SARS-CoV-2 variant would occur, the regime would immediately react and change the probability. We propose the Markov-switching model to determine COVID-19 policies and predict SARS-CoV-2 variants.

IMPORTANCE
Using regime-switching models, we attempted to determine whether there is a link between changes in severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) variants and infection waves, as well as forecasting new SARS-Cov-2 variants. We believe that our study makes a significant contribution to the field because it proposes a new approach for forecasting the ongoing pandemic, and the spread of other infectious diseases, using a statistical model which incorporates unpredictable factors such as human behavior, political factors, and cultural beliefs.
Seasonal Activity of Soil Peroxidase in Drained Swamp Pine Forests of Western Siberia: Systemic-Ecological Analysis
Authors: Efremova T. T. , Efremov S. P. , Avrova A. F. 
Published: October 2023

Abstract
We studied a mesotrophic swamp drained 25 years ago in the northern part of the Ob’ River basin (56°23′710″ N, 84°34′043″ E). In peat soils (0–30 cm layer), the weighted average of peroxidase activity for the season (base level) constituted 14.4, 21.9, and 70 units (mL I/g abs. dry soil per 2 min) in the areas subjected to weak, moderate, and intensive drainage, respectively. Second-order parabola is the most adequate function of the main trend of development of seasonal fluctuations in peroxidase activity. Numerical values and signs of the parabolic trend parameters showed that the average peroxidase activity decreased from June to October weekly by 4.4, 7.6 and 15.2 units with weekly average acceleration by 0.31, 0.59 and 1.54 units in the mode of weak, moderate, and intensive drainage, respectively. The seasonal wave of peroxidase activity relative to the baseline level was characterized by a June increase in growth rates with a maximum in the layer of 0–10 cm. In July, there was a decrease in the growth rate according to the depth of reclamation: in the modes of weak and moderate drainage, the process embraced the entire soil profile in August; in case of intensive drainage, in October. The enzyme activity significantly and positively correlated with the soil volumetric water content and pH, negatively correlated with redox potential, and displayed multidirectional relationship with the soil temperature. Environmental conditions acted as mutually replacing parameters when assessing their contribution to the seasonal dynamics of peroxidase, creating the effect of interchangeability of environmental gradients. Canonical determination indices approximated the cumulative impact of the discussed set by 52–74%, depending on the depth of reclamation. Canonical weights showed that the hydrothermal regime was the main factor, regulating the seasonal activity of peroxidase: according to canonical correlations, temperature was the main factor under the conditions of weak drainage, moisture was the main factor under the conditions of intensive drainage, and both moisture and temperature were important factors under the conditions of moderate drainage. The peroxidase activity and the depth of humification in peat soils of different degrees of drainage were interrelated in 87% of cases.