bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accurate integration of trimmed cells based on Bezier approximation
Authors: Hosseini Seyed Farhad , Gorji Mahan , Düster Alexander 
Published: March 2023

AbstractIn this work, a new adaptive integration method for simulation of two‐dimensional linear elasticity problems is presented. The main benefit of the proposed method is the reduction of the computational cost by lowering the number of integration points required to reach a certain level of accuracy. The main concept of the proposed method is to calculate new weights for trimmed cells employing the advantage of Bezier parametric curves. Within this concept, it is possible to map a square to a triangle with one curved edge where any curved edge is approximated by a parametric Bezier curve. In this way, a new set of Gaussian quadrature points is introduced for each trimmed cell in a fast and robust way. Besides main mapping cases, the integration method includes supplementary cases as well to increase the robustness and generality of the method. In the next step, the proposed method is implemented in a two‐dimensional fictitious domain code in MATLAB to solve structural problems. The results will be compared to those obtained through the commercial finite element code ABAQUS. It is shown that the proposed method is accurate and robust.
Aspects of accuracy and uniqueness of solutions in data‐driven mechanics
Authors: Bartel Thorsten , Harnisch Marius , Menzel Andreas , Schweizer Ben 
Published: March 2023

AbstractData‐driven methods provide great potential for future applications in engineering, for example in terms of more efficient simulations. Conventional material models and the associated constitutive equations are substituted by a minimization of a distance between so‐called material and mechanical states, which, however, leads to non‐unique solutions. The aim of this paper is to analyze the influence of the chosen initial values on the accuracy of the obtained results. Furthermore, Mixed Integer Quadratic Programming (MIQP) is implemented and its applicability to data‐driven mechanics is assessed.
The high cycle fatigue testing of High‐Performance Concretes using high frequency excitation
Authors: Madadi Hamid , Steeb Holger 
Published: March 2023

AbstractThe effect of fatigue failure in brittle materials like (ultra) High Performance Concrete (UHPC) due to cyclic loading causes unexpected failure that consequently results in heavy costs in marine and civil structures. To characterize the effect of fatigue, cyclic loading tests are performed, and “the number of cycles to failure” are experimentally determined. One problem with these kinds of tests is that such experimental investigations are potentially expensive, i.e., time‐consuming process since the number of loading cycles could be extremely high. Further, within the different damage phases of the cycling tests, one has no access to the small‐scale, i.e., microscopical evolution of (micro‐)cracks. Additionally, a full characterization of the small‐strain stiffness evolution of the material is challenging. The goal of the research investigation is to combine a (large amplitude) High Cycle Fatigue experiment with a (low amplitude) Dynamic Mechanical Analysis (DMA). Using a setup based on the piezoelectric actuator, the (rate‐dependent) mechanical properties of the material in tangential space, and the failure modes of the material will be examined accurately. The excitation frequency is between 0.01 Hz to 1000 Hz which allows for reducing the experimental investigation time to failure. Further, it allows investigating the effect of frequency on the number of cycles to failure. Firstly, experimental results for HPC and berea sandstone samples will be presented. Harmonic experimental data include (direct) strain measurements in axial and circumferential directions as well as forces in axial directions. In addition, the resulting complex Young's modulus and evolving damage‐like “history” of HPC and berea sandstone specimens will be shown.
A comparison of different nonlinear shell theories for rotating fluid‐filled structures
Authors: Schmidt Rico , Ams Alfons 
Published: March 2023

AbstractRotating fluid‐filled shell structures can be used for different applications in technique. Because of spin‐softening as well as stress‐stiffening it is essential to consider geometrical non‐linearities. Additionally, shear deformation is getting important in case of thick shells. At this point different theories from KIRCHHOFF‐LOVE (no shear deformation) and MINDLIN‐REISSNER (first order shear deformation) are compared with each other.For both theories the nonlinear kinematics are shown and therewith the HAMILTON's principle is evaluated to receive the equations of motion. The solution of the corresponding eigenvalue problem is done with a global RITZ approach on the one hand, on the other hand with local FE‐discretization. Different results of rotating and non‐rotating cylindrical shells with respect to their eigenfrequencies are presented and compared. Furthermore, experimental data is used for validation.
Hyperelastic material modelling using symbolic regression
Authors: Abdusalamov Rasul , Hillgärtner Markus , Itskov Mikhail 
Published: March 2023

AbstractRecently, data‐driven approaches in the field of material modeling have gained significant attention. A major advantage of these approaches is the direct integration of experimental results into the models. Nevertheless, artificial neural networks (ANNs) are especially challenging to interpret from a physical point of view, since internal processes of ANNs are difficult to understand.In this work a new automatic method for the generation of constitutive models for hyperelastic materials is introduced. The presented method is based on symbolic regression, which is a genetic algorithm. Thereby, a mathematical model in the form of an algebraic expression is found that fits the given data as accurately as possible and has a compact representation. The strain energy density function is determined directly as a function of the strain invariants. The proposed ansatz is embedded into a continuum mechanical framework combining the benefits of known physical relations with the unbiased optimization approach of symbolic regression. Benchmark tests for the generalized Mooney‐Rivlin model for uniaxial, equibiaxial and pure shear tests are presented. Finally, the presented procedure is tested on a temperature‐dependent dataset of a thermoplastic polyester elastomer. A good agreement between obtained material models and experimental data is demonstrated.
Molecular Dynamics Study on the Effect of Interfacial Cellullose Polymers in Strengthening the Stress Transfer Between Alumina Nanoparticles and Epoxy
Authors: Al-Maharma Ahmad Y. , Bamer Franz , Markert Bernd 
Published: March 2023

AbstractCellulose polymers are widely used to fabricate green composites, implemented as fiber, matrix, and adhesive material between them. In this study, cellulose polymers are used as interphase material between spherical nanoparticles of hydroxylated alumina (Al2O3) and epoxy. Molecular dynamics simulations using the large‐scale atomic/molecular massively parallel simulator (LAMMPS) are utilized to investigate the effect of the cellulose content on the stiffness and tensile strength of epoxy/alumina nanocomposites. Polymer consistent forcefield (PCFF) and its supplement provided by MedeA software (PCFF+) define the interactions between the atoms. The simulation results indicate that incorporating cellulose into epoxy would increase the stiffness and strength properties considering that the cellulose polymers do not experience any agglomeration in the hosting matrix and have good interfacial adhesion with epoxy and alumina. This interfacial adhesion is needed since inserting cellulose polymers between alumina nanoparticles and epoxy would increase the porosity in the interphase region, limiting the stress transfer at the interphase and reducing the tensile strength of epoxy‐alumina nanocomposites.
Analysis of vibration characteristics based on variable‐angle hybrid laminates
Authors: Sun Ying , Yu Xiao , Ren Jiajun , Wang Xianfeng , Xiao Jun 
Published: March 2023

AbstractComposite laminates are widely used in the aerospace field. Aircraft wings are subject to strong aerodynamic interference, which produces resonance, instability and other phenomena. To avoid this resonance and reduce the vibration of laminates it is essential to adopt a variable‐stiffness laminate. Methods for changing the stiffness include designing the fiber path and inserting a damping layer. The former can increase the natural frequency but does not improve the damping performance. Here we demonstrate how, depending on the resin's agglomeration, variable‐angle hybrid laminates made of carbon fiber and Kevlar fiber increase the damping performance. By using a short beam shear test we found that sandwich hybrid samples with a hybrid ratio of 50% performed better than inter‐laminar hybrid samples, which increased by 19.5%. Based on the results of interlayer properties, 8 layers of pure carbon fiber (CF) laminates and carbon fiber‐kevlar fiber (CF‐KF) hybrid laminates with variable angles were manufactured. Modal tests demonstrated that the change in fiber angle had a greater impact on the natural frequency, the maximum result of which was seen at an angle of <60|75>. By inserting, the KF layer the damping ratio of the <15|30> hybrid laminate increased by 5.45% more than pure CF laminates. These results can be referenced to improve the damping parameters of variable‐angle laminates.
ZnO nanowire‐decorated Al2O3/graphene aerogel for improving the thermal conductivity of epoxy composites
Authors: Lu Zijian , Wu Wei , Drummer Dietmar , Wang Yi , Liu Chao , Li Shuo , Zhao Xintong 
Published: March 2023

AbstractIt is of great significance to study new thermal conductivity filler in practical thermal management application. In this study, a multi‐scale assembled thermal conductivity composite Al2O3‐ZnO NWs/GO/EP was developed. The test results showed that the composite has good thermal conductivity and mechanical properties with low filler content. When the GO content is 1.5 wt% and the Al2O3‐ZnO NWs content is 25 wt%, the thermal conductivity of the composites reaches 2.15 W/mK, which is improved by about 1032% compared with the pure epoxy resin, and the tensile strength of the composites is maintained at a high level. The problems of high filling capacity and poor mechanical properties of alumina filler were effectively solved. It provides a new idea for preparing the filled thermal conductivity composites with low filling capacity and high thermal conductivity.
Effects of fabrication parameters on the mechanical properties of short basalt‐fiber‐reinforced thermoplastic composites for fused deposition modeling‐based 3D printing
Authors: Hua Luqing , Wang Xin , Ding Lining , Zeng Siheng , Liu Jianxun , Wu Zhishen 
Published: March 2023

AbstractThis study develops sustainable and recyclable basalt fiber (BF)‐reinforced flexible plastic low‐temperature polyamide (L‐PA) filaments for fused deposition modeling (FDM)‐3D printing and optimizes fabrication parameters to achieve eco‐friendliness, high mechanical performance, and lightweight FDM‐fabricated composite parts. Herein, 15 wt% fiber‐filled composite filaments were prepared by an extrusion process. Three manufacturing parameters, including printing temperature, printing speed, and layer height, were investigated for their effects on the tensile and compression properties through Taguchi L9 orthogonal experiments. To obtain a suitable printing temperature range, the thermal behaviors of the composite filaments were characterized by differential scanning calorimetry, thermogravimetric analysis, and melt flow factor measurements. In addition, the FDM‐printed specimen surface and tensile fracture interface after tensile tests were observed and analyzed by SEM. Results show that the printing temperature has the greatest effect on the mechanical properties of the BF/L‐PA composites, followed by the layer height, whereas the printing speed has the least effect. This indicates that better mechanical properties can be obtained at higher printing temperatures and lower layer heights. Compared with neat L‐PA, adding BF to L‐PA improves the tensile modulus, tensile strength, and specific energy absorption per volume without sacrificing ductility, showing the maximal increases of 176.6%, 142.0%, and 172.2%, respectively, as compared with neat L‐PA. A SEM micrograph reveals that the primary factors for these improvements are the fibers acting as reinforcement filling in the L‐PA matrix and the good bonding properties between the adjacent infills in a single layer and among successive layers.
Statin persistence and adherence among older initiators: A nationwide cohort study using the national health insurance claims database in Japan
Authors: Tomida Junko , Yoshida Tomoji , Senda Shoichi , Sato Tsugumichi , Nakatsuma Akira , Iihara Naomi 
Published: March 2023

AbstractPurposeThis study clarifies the reality of persistence and adherence to statins in older Japanese people who initiated statin use and compares it between primary and secondary prevention cohorts.MethodsThe nationwide study using the national claims database targeted statin initiators aged ≥55 years from FY2014 to FY2017 in Japan. Persistence and adherence to statins were analyzed overall and according to subgroups based on sex, age stratum, and prevention cohorts. Permissible gap of median days that statins were supplied per prescription to an individual was employed. Persistence rates were estimated as Kaplan–Meier estimates. Poor adherence during persistence was evaluated and defined as <0.8 of the proportion of days covered.ResultsOf 3 675 949 initiators, approximately 80% initiated statin use with strong variants. The persistence rate at 1 year was 0.61. Poor adherence to statins during persistence was 8.0% in all patients and this value gradually improved with increasing age. Persistence rate and adherence were lower for the primary prevention cohort than for the secondary prevention cohort, and a notable sex difference was observed for the secondary prevention cohort, which was lower in females but was almost never and slightly observed in the primary prevention cohorts without and with high‐risk factors, respectively.ConclusionsMany statin initiators discontinued statins shortly following statin initiation but adherence while on statin therapy was good. Attentively watching older patients not to discontinue statins and listening to their reasons for discontinuation are required, especially for initiators in primary prevention and females in secondary prevention.
Cognitive diagnostic analysis of students' mathematical competency based on the DINA model
Authors: Xu Tianshu , Wu Xiaopeng , Sun Siyu , Kong Qiping 
Published: March 2023

AbstractConsidering the importance of mathematics in modern society, it is crucial to understand the cognitive processes involved in the acquisition of complex mathematical competency. As a new generation of evaluation theory, cognitive diagnosis has its unique advantages in personalized evaluation. Based on the mathematical cognitive framework of Trends in International Mathematics and Science Study (TIMSS)‐2011 and the Chinese mathematics curriculum, this research has formed a mathematical competency model composed of seven cognitive attributes. Sixty‐seven released mathematical items for the fourth grade in TIMSS‐2011 were used as assessment tools in this study. The deterministic inputs, noisy, “and” gate model was selected as the cognitive diagnosis model in this research, and the parameters of the model were evaluated according to the response data, based on which the effectiveness of the assessment tool was further verified, forming the evaluation framework of students' mathematical competency. This framework was used to analyze the data of 573 students' mathematical competency from Shanghai, China, specifically from three aspects: attribute mastery probability, learning path, and knowledge structure. Results show that students' performance in mastering attributes of mathematical cognition is excellent on the whole; some students' learning paths are leapfrog; there are certain differences in students' knowledge structure despite that they have the same total score. This research is performed as a systematic case study of the evaluation of students' mathematical competency and also provides a new perspective in assessing other knowledge and skills.
Mussel‐inspired double cross‐linked interpenetrating network with unique mechanical properties using di‐diol complexation
Authors: Malakar Amit , Mandal Samir , Sen Gupta Ria , Manna Kunal , Parasuram Sampath , Misra Ashok , Bose Suryasarathi 
Published: March 2023

AbstractPolymer nanocomposites with exceptionally high mechanical properties owing to strong interfacial attraction have garnered tremendous interest in the research community. In general, tough and robust polymer nanocomposites are usually obtained via dispersing a nano‐flaky filler in the polymer matrix, although the strategy is only sometimes practically viable. To this end, in this work, a facile strategy has been adopted to achieve a strong and tough polymer nanocomposite. A novel mussel‐inspired full interpenetrating polymeric network (IPN) consisting of polyvinylalcohol and polydopamine was prepared. This technique helped integrate the advantages of dopamine chemistry with forming a full IPN using Borax as a common crosslinker. The infusion of 1 wt% acid‐modified carbon nanotubes (ACNT) in the IPN matrix helped greatly improve the current state‐of‐the‐art. The synergistic effect of nano‐reinforcement and formation of ester linkage through a substantial amount of di‐diol complexation dominated and accounted for the significant enhancement of mechanical properties. This is further supported by decreased intensity of free OH groups in the FTIR investigations, viscosity enhancement from rheological behavior, and temperature‐dependent dynamic mechanical property analysis. Such an IPN structure is a promising way to enhance mechanical properties.
The relationship between trait mindfulness and resilience: A meta‐analysis
Authors: Zhang Juan , Mao Yidi , Wang Yihui , Zhang Yihan 
Published: March 2023

AbstractResilience is a positive psychological resource that promotes health. Trait mindfulness was found to be related to resilience. However, previous studies on this relationship have shown contradictory results. The current meta‐analysis explored the relationship between trait mindfulness and resilience based on a three‐level random‐effects meta‐analysis model. A significant and positive relationship between trait mindfulness and resilience (r = 0.385; p < 0.0001) was revealed by analyzing 197 effect sizes from 103 studies. Furthermore, the subsequent moderator analysis found that the facet of mindfulness (e.g., awareness, nonjudging) (F(6, 190) = 6.181; p < 0.001), measurement of mindfulness (e.g., the Mindful Attention Awareness Scale) (F(7, 191) = 4.758; p < 0.001), aspect of resilience (e.g., family resilience) (F(5, 191) = 3.455; p < 0.05), measurement of resilience (e.g., the Connor–Davidson Resilience Scale) (F(11, 185) = 2.256; p < 0.05), and age (F(1, 150) = 4.588; p < 0.05) acted as significant moderators. Overall, this study confirmed the positive relationship between trait mindfulness and resilience, suggesting that people with higher levels of trait mindfulness were more likely to have higher levels of resilience. The current findings provided insightful information for interventions targeted at improving resilience.
Event‐triggered adaptive control of strict‐feedback nonlinear systems under output constraints and unknown control direction
Authors: Wang Chao , Wang Yujuan , Dai Yunfei , Ma Yu 
Published: March 2023

AbstractThis article is concerned with the tracking control problem for a class of uncertain nonlinear systems under output constraints and unknown control direction. To address the unknown control direction and uncertain system parameters, the adaptive compensation mechanism and Nussbaum gain based control technique are employed. In addition, to reduce the communication burden and computing cost, the event‐triggered control mechanism is introduced into the proposed control scheme, in which both the controller and the parameter estimator are event‐triggered, distinguishing itself from the traditional control method based on event‐triggered mechanism. Two different adaptive event‐triggered control schemes based on the fixed threshold strategy and relative threshold strategy are provided, under both of which, the boundness of all signals in the closed‐loop system are guaranteed and the output of system remains in the constraints. More importantly, the Zeno behavior can be avoided under both the two proposed event‐triggered control schemes. The effectiveness of the proposed event‐triggered control schemes are confirmed by the numerical simulation.
Automatically digital extracellular vesicles analyzer for size‐dependent subpopulation analysis in surface plasmon resonance microscopy
Authors: Feng Xie , Zhai Chunhui , Xu Jiaying , Yang Yuting , Yu Hui 
Published: March 2023

AbstractThe heterogeneity in extracellular vesicles (EVs) introduces an extra level of complexity in small EV‐based liquid biopsy for cancer diagnosis. Surface plasmon resonance microscopy (SPRM) offers sensitive and multifunctional analysis for single tiny EVs. However, the EV SPRM image analysis has been extremely laborious and time‐consuming due to the low contrast and bad signal‐to‐noise ratio. Herein, we present a digital EV analyzer (DEA), a software package, for the automatic analysis of EV data in the SPRM platform. This package enabled fully automated single EV identification, digital counting, sizing EV, and quantification of dwell time. Integrated with a classification algorithm and intelligent searching algorithm for subpopulation analysis, DEA was able to accurately group EVs with five different origins. We hope this software tool would largely promote the application of SPRM technology into cancer diagnosis with EVs.
Introduction: Stranger, Guest, Researcher – A Case for Domestic Ethnography in Migration Studies
Authors: Boccagni Paolo , Bonfanti Sara 
Published: March 2023

AbstractBeing a guest in the home of someone else is a meaningful experience in several ways, including the scope it gives for an ethnographic understanding of people’s life conditions, routines and emplaced forms of homemaking. This introduction is an invitation to appreciate the potential of home visits and stays, particularly in research on migrants and refugees, to appreciate both the infrastructural aspects of one’s dwelling conditions and the underlying lived experiences. Home visits, possibly as part of broader research strategies, help to situate people’s identities and narratives in different and more or less unequal household arrangements, at certain points of their biographical, housing and migration trajectories. Methodwise, we discuss the negotiations of roles and identities, as guests and researchers, that are inherent in this fieldwork option, with the attendant relational implications and ethical dilemmas. This overarching discussion paves the way for the case studies presented in the book, across different target groups, locations and scales.