bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Food-Simulating Liquids on the Leachability of Plasticizers from Dental Tissue Conditioners
Authors: Wan Ali Wan Nor Syariza , Parker Sandra , Patel Mangala
Published: February 2024

Objective Tissue conditioners are composed of poly(ethyl methacrylate) (PEMA) powder and plasticizer/ethanol mix liquid. Butyl phthalyl butyl glycolate (BPBG) plasticizer is commonly used in tissue conditioners, but the main concern with phthalate plasticizer is its leachability and biocompatibility, especially the estrogenic activity and cytotoxicity of phthalate. Therefore, acetyl tributyl citrate (ATBC) plasticizer has been introduced and formulated as plasticizer in tissue conditioner; however its leachability characteristics are still unknown. Furthermore, the effect of foodsimulating liquids toward leachability of BPBG and ATBC plasticizers has not been documented. The objective of this study was to compare the effect of food-simulating liquids on the leachability of plasticizers and hardness of two experimental tissue conditioners containing BPBG and ATBC plasticizers.

Materials and Methods Ten experimental materials were prepared using PEMA polymer powder with 95% plasticizer (BPBG and ATBC) and 5% ethanol by volume, using powder to liquid ratio of 1.67:1, and the thickness was controlled at 3 mm. Shore A hardness value was measured after immersion in distilled water, artificial saliva, 25% ethanol/water mix, 3% citric acid, and coconut oil at 37°C. Measurements were taken at 2 hours and 1, 2, 3, 4, 7, 10, 14, 21, 28, 42, 56, and 84 days. Six readings were taken for each sample and hardness change was calculated and statistically analyzed using Wilcoxon signed-rank test.

Results Increase in hardness value was noted for both plasticizers over time with the highest increase was when immersed in coconut oil. Shore A hardness value was significantly higher in ATBC after 84 days of immersion in all food-simulating liquids. The increase in hardness is due to plasticizer/ethanol leaching; however, as ethanol content was the same (5%), the hardness change is attributed to the leaching of plasticizers.

Conclusion Leaching of both plasticizers was highest in coconut oil indicating that tissue conditioners may have a shorter intraoral lifetime in patients eating high-fat diet.
MEMS highly sensitive and large-area force plate for total ground reaction force measurement of running ant
Authors: Takahashi Hidetoshi , Kohyama Sumihiro , Takahata Tomoyuki , Shimoyama Isao
Published: February 2024

Terrestrial insects exhibit agile manoeuvrability while running. However, the ground reaction force (GRF) in small insects remains poorly understood owing to its size and acting force. Here, we present a force plate for the measurement of total GRF during the running motion of ants with a force on the order of several tens of μN. The proposed force plate consists of a sufficiently large plate for several step cycles and four supporting cantilevers with highly sensitive piezoresistive elements. The plate and sensor chips were fabricated separately and combined during postprocessing. Two sizes of force plates were designed and fabricated for a large ant (Camponotus japonicas) and small ant (Messor aciculatus) with force resolution less than 1 μN. The developed force plates were calibrated by applying vertical forces at 32 points on the plate. Using the fabricated force plate, we measured the total GRF over several step cycles as the ant ran along the plate. Consequently, it was suggested that the ant ran with small vibrations in the direction of gravity.
Effects of micromachining on anti-oxidant elution from a mechanically-adaptive polymer
Authors: Mueller Natalie N , Kim Youjoung , Ocoko Mali Ya Mungu , Dernelle Peter , Kale Ishani , Patwa Simran , Hermoso Anna Clarissa , Chirra Deeksha , Capadona Jeffrey R , Hess-Dunning Allison
Published: February 2024

Intracortical microelectrodes (IMEs) can be used to restore motor and sensory function as a part of brain–computer interfaces in individuals with neuromusculoskeletal disorders. However, the neuroinflammatory response to IMEs can result in their premature failure, leading to reduced therapeutic efficacy. Mechanically-adaptive, resveratrol-eluting (MARE) neural probes target two mechanisms believed to contribute to the neuroinflammatory response by reducing the mechanical mismatch between the brain tissue and device, as well as locally delivering an antioxidant therapeutic. To create the mechanically-adaptive substrate, a dispersion, casting, and evaporation method is used, followed by a microfabrication process to integrate functional recording electrodes on the material. Resveratrol release experiments were completed to generate a resveratrol release profile and demonstrated that the MARE probes are capable of long-term controlled release. Additionally, our results showed that resveratrol can be degraded by laser-micromachining, an important consideration for future device fabrication. Finally, the electrodes were shown to have a suitable impedance for single-unit neural recording and could record single units in vivo.
Structural and optical investigations of RE3+: Yb, Er, Sm, Nd, Ce-doped multi-functional silica glasses for photonic applications
Authors: J Gracie P , Yasmin  , Geetha D
Published: February 2024

The influence of various trivalent lanthanides was investigated in the silica phosphate multi-component glass matrix, synthesized by the sol-gel method. The prepared glasses were analyzed to explore the degree of bandwidth amplification for telecommunication systems, and the potentiality of lasing media and smart glass films. Alkaline earth metal ions of Ca2+ were effectuated as a glass modifier, mediating the formation of non-bridging oxygen with the glass formers, and imputing favorable structural attributes to the glasses for versatile applications. The bonding parameter derived from the average nephelauxetic ratio implies covalency around the rare earth ion sites in the Er3+ and Nd3+ doped systems, while the Sm3+ doped glass exhibits ionicity. In the silica-based glass matrix singly doped with Yb3+, the coexistence of Yb3+/Yb2+ ions was evidenced. Transitions across 4f14 and 4f135d levels of Yb2+, with an experimental lifetime of 45.8 ns would provide prospective pulsed yellow lasers, for non-invasive therapeutics. Er3+ doped glass evinced a large bandwidth of 93.775 nm at 1477 nm and a high quantum efficiency of 97%, favorable for O + E + S-band telecommunication networks. The transition corresponding to

4

G

5

/

2

→
6

H

7

/

2

of Sm3+ and

2

G

7

/

2

→
4

I

9

/

2

of Nd3+ is suggestive that the respective doped glasses could be devised into solid-state red and green laser sources. Novel near-infrared emission at 1476 nm was also evidenced in the Sm3+ and Nd3+ doped systems. Prominent absorption at 280 nm and complete transparency in the visible region observed in the Ce3+ mono-doped system make it ideal for smart glasses as UVB and UVC shielding films.
A computational study of a laminar methane–air flame assisted by nanosecond repetitively pulsed discharges
Authors: Shao Xiao , Kabbaj Narjisse , Lacoste Deanna A , Im Hong G
Published: February 2024

Nanosecond repetitively pulsed (NRP) discharges have been considered a promising technique for enhancing combustion efficiency and control. For successful implementation, it is necessary to understand the complex plasma–combustion interactions involving chemical, thermal, and hydrodynamic pathways. This paper aims to investigate the mechanisms enhancing a laminar methane–air flame assisted by NRP discharges by high fidelity simulations of the jet-wall burner employed in a previous experimental study. A phenomenological plasma model is used to represent the plasma energy deposition in two channels: (1) the ultrafast heating and dissociation of

O
2

resulting from the relaxation of electronically excited

N
2

, and (2) slow gas heating stemming from the relaxation of

N
2

vibrational states. The flame displacement, key radical distribution and flame response under plasma actuation are compared with experimental results in good agreement. The computational model allows a systematic investigation of the dominant physical mechanism by isolating different pathways. It is found that the kinetic effect from atomic O production dominates the flame dynamics, while the thermal effect plays a minor role. Hydrodynamic perturbations arising from weak shock wave propagation appear to be sensitive to burner geometry and is found to be less significant in the case under study.
Hydrogenation driven ultra-low lattice thermal conductivity in β
12 borophene
Authors: Sharma Ashish , Rangra Vir Singh
Published: February 2024

Borophene gathered large interest owing to its polymorphism and intriguing properties such as Dirac point, inherent metallicity, etc but oxidation limits its capabilities. Hydrogenated borophene was recently synthesised experimentally to harness its applications. Motivated by experimental work, in this paper, using first-principles calculations and Boltzmann transport theory, we study the freestanding β
12 borophene nanosheet doped and functionalised with hydrogen (H), lithium (Li), beryllium (Be), and carbon (C) atoms at different β
12 lattice sites. Among all possible configurations, we screen two stable candidates, pristine and hydrogenated β
12 borophene nanosheets. Both nanosheets possess dynamic and mechanical stability while the hydrogenated sheet has different anisotropic metallicity compared to pristine sheet leading to enhancement in brittle behaviour. Electronic structure calculations reveal that both nanosheets host Dirac cones (DCs), while hydrogenation leads to shift and enhancement in tilt of the DCs. Further hydrogenation leads to the appearance of additional Fermi pockets in the Fermi surface. Transport calculations reveals that the lattice thermal conductivity changes from 12.51 to 0.22 W m−1 K−1 (along armchair direction) and from 4.42 to 0.07 W m−1 K−1 (along zigzag direction) upon hydrogenation at room temperature (300 K), demonstrating a large reduction by two orders of magnitude. Such reduction is mainly attributed to decreased phonon mean free path and relaxation time along with the enhanced phonon scattering rates stemming from high frequency phonon flat modes in hydrogenated nanosheet. Comparatively larger weighted phase space leads to increased anharmonic scattering in hydrogenated nanosheet contributing to ultra-low lattice thermal conductivity. Consequently, hydrogenated β
12 nanosheet exhibits a comparatively higher thermoelectric figure of merit (∼0.75) at room temperature along armchair direction. Our study demonstrates the effects of functionalisation on transport properties of freestanding β
12 borophene nanosheets which can be utilised to enhance the thermoelectric performance in two-dimensional (2D) systems and expand the applications of boron-based 2D materials.
Multi-scale residual neural network with enhanced gated recurrent unit for fault diagnosis of rolling bearing
Authors: Liao Weiqing , Fu Wenlong , Yang Ke , Tan Chao , Huang Yuguang
Published: February 2024

As the key component of rotating machinery, effective and reliable fault diagnosis of rolling bearing is particularly critical for promoting production safety and economic benefits. The powerful representation learning ability of convolutional neural network (CNN) enables it to effectively extract fault information from vibration signals of rolling bearing. Nevertheless, challenges are faced by CNN in extracting features at multi-scale and capturing temporal features. With regard to this issue, a hybrid deep learning model that incorporates the multi-scale residual neural network (MSRN) with the enhanced gated recurrent unit (EGRU), namely MSRN-EGRU, is proposed in this paper. To begin with, MSRN is designed by introducing multi-scale structure and residual connections into CNN for extracting local features effectively and improving the feature representation of the model. Then, the extracted local features are input into EGRU to further extract temporal features, where EGRU is proposed by improving GRU structure and embedding scaled exponential liner unit (SELU), which enhances the nonlinear modeling and memory ability. Eventually, the obtained features are processed by α-Dropout and global average pooling before being inputted into the softmax layer for fault diagnosis. To validate the effectiveness of the proposed model, three baseline models and two ablation models were employed for comparative experiments with two bearing datasets. The experimental results reveal that the proposed model achieves commendable performance in terms of accuracy, robustness, and convergence for fault diagnosis of rolling bearing.
Using high-precision travel time extraction to detect time deviation of seismic instruments
Authors: Zhang Han , Ye Fang , Jin Chun-Wei , Cai Jin-Hui
Published: February 2024

The method of seismic ambient noise cross-correlations (NCFs) has been demonstrated to be applicable for time offset measurement, especially in evaluating instrument clocks. Continuous recording of seismic ambient noise data makes it possible to analyze the performance of seismic instruments online. However, long-term cross-correlation and stacking calculations are required to obtain accurate travel time from ambient noise, which greatly reduces the time resolution of instrument performance detection. Therefore, we propose a travel time extraction method based on time-frequency analysis, which could obtain the travel time accurately even though the NCF has a low signal-to-noise ratio (SNR), and it is applied to the measurement of clock offsets in seismic instruments. The method combines S Transform and dictionary learning to improve the SNR of NCFs, and uses a peak extraction algorithm based on short-time Fourier transform to obtain accurate travel times. Additionally, the travel time drift of the station pair can be obtained by calculating the travel time difference between causal and acausal parts of NCFs. Using the data from ambient noise observations and the real data with time errors to verify that the proposed method can obtain accurate travel time for NCF with SNR lower than 6 and it can pick up a time offset as low as one sampling point, the detectable change is 0.046% of travel time, which is crucial for detecting weak changes in the performance of seismic instruments.
Research of ordinal model fusion based apple grading
Authors: Bi Shuhui , Qu Xinhua , Shen Tao , Zhao Qinjun , Ma Liyao
Published: February 2024

Near infrared spectrum has been applied for the rapid non-destructive prediction and classification of the internal soluble solids content (SSC) of apples, due to its rapid, non-destructive and non-polluting nature. However, current apple grading methods do not make full use of the orderliness relationship existing in the apple grading labels. Therefore, ordinal model is introduced in the issue of apples grading based on the internal SSC. In details, the orderliness in the classification model is considered and ordinal regression is combined with apple classification model to establish ordered partition neural network and ordinal regression extreme learning machine, respectively. Meanwhile, to address the problems of poor applicability of single prediction model and the grading uncertainty associated with compulsory segmentation of grading boundaries, a Gaussian mass function generating method is proposed based on the distance between the predicted ordinal class labels and the real grading boundaries, and the multiple models can be fused through the Dempster combination rule, making a fuller description of the uncertainty problem on ordinal class labels prediction, providing a research basis for online non destructive testing grading of apples. Finally, the multiple model fusion process is fully demonstrated by simulation examples, the grading accuracy of Yantai Red Fuji apples is also improved than single ordinal model.
Graph plotting of 1-D motion in introductory physics education using scripts generated by ChatGPT 3.5
Authors: Ramkorun Bhavesh
Published: February 2024

Introductory physics courses often necessitate students to graphically represent one-dimensional (1-D) motion and derive various physical parameters. Physical quantities are often solved by calculating either slope or the area under the graph. Instructors and students who do not have access to paid software must plot graphs by hand. This paper explores three introductory physics examples related to 1-D motion, and employs ChatGPT 3.5 to generate scripts that will produce graphs from raw data. It can generate scripts, based on accurate user inputs, in free programming languages like Python and/or GNU Octave to enable efficient graph plotting. Examples will be provided on calculating the slope of a distance–time graph and determining the area under a velocity–time graph. Given raw data, ChatGPT 3.5 may exhibit occasional inaccuracies when solving for physical parameters. However, user can communicate in English to modify the output. The author does not endorse the use of ChatGPT for academic misconducts such as assisting students to cheat in problem solving. Instead, ChatGPT is presented as a tool to enhance data visualisation for both instructors and students, which can potentially improve learning environments in introductory physics. This paper lays the groundwork for future initiatives, beyond the plotting of 1-D motion graphs, aiming to integrate artificial intelligence to assist more complex motion studies in physics learning environments.
Theoretical analysis of introducing CeOx as a passivation layer: an innovative approach to boosting CIGS solar cell efficiency
Authors: Naceri Leila , Belarbi Mousaab
Published: February 2024

In this paper, we present a novel structure, AZO/CeOx/SnS2/CIGS/a-Si/Ag., simulated using SCAPS-1D. The structure features CeOx as a passivation layer, integrates SnS2 as an auxiliary absorber layer alongside the primary CIGS layer, and employs a-Si as a buffer layer. Our investigation focuses on evaluating the impact of material parameters on various electrical characteristics such as open-circuit voltage (Voc), short-circuit current (Jsc), efficiency (η), and fill factor (FF). We analyze the influence of layer thickness on the aforementioned characteristics and scrutinize the effects of temperature variation and series resistance on cell performance. After detailed calculations, we found that optimizing these parameters led to excellent performances, achieving an efficiency of 30.11%. This achievement was obtained under specific conditions, including the following layer thicknesses: CeOx (0.7 μm), CIGS (1.2 μm), and a-Si (0.1 μm), along with an optimal temperature of 302 K. This study aims to provide valuable insights to device manufacturers for enhancing the efficiency of CIGS solar cells.
An advanced theoretical approach to study super-multiperiod superlattices: theory vs experiments
Authors: Dashkov Alexander Sergeevich , Khakhulin Semyon Andreevich , Shapran Dmitrii Alekseevich , Glinskii Gennadii Fedorovich , Kostromin Nikita Andreevich , Vasiliev Alexander Leonidovich , Yakunin Sergey Nikolayevich , Komkov Oleg Sergeevich , Pirogov Evgeniy Viktorovich , Sobolev Maxim Sergeevich , Goray Leonid Ivanovich , Bouravleuv Alexei Dmitrievich
Published: February 2024

A new theoretical method to study super-multiperiod superlattices has been developed. The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach. This method was applied to examine the finest quality samples of super-multiperiod Al0.3Ga0.7As/GaAs superlattices grown by molecular beam epitaxy. The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method. For the first time, the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted. The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram, transition energies, relaxation rates, and gain estimation. It has achieved a remarkably low 5% error compared to the commonly used method, which typically results in a 25% error, and allowed to recover the superlattice parameters. The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters. The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm, as was observed in photoreflectance experiments. The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.
MSL goniospectrophotometer measurement model
Authors: Molloy E , Koo A
Published: February 2024

Measurements of both hemispherical reflectance and the bidirectional reflectance distribution function (BRDF) are of interest to a wide range of industries including computer graphics, remote sensing, lighting design, and cosmetics. The scale of directional reflectance is often realised at national metrology institutes using goniospectrophotometers, and by integrating BRDF measurements made over the hemisphere, the scale of hemispherical reflectance can also be realised. This paper describes the measurement model for BRDF and hemispherical reflectance using the MSL goniospectrophotometer, which uses rotation stages to adjust the angle of the sample. The measurement model is applied to measurements of a white Spectralon sample and a white ceramic tile to demonstrate the performance of the instrument. The relative standard uncertainty in the BRDF of a white Spectralon sample at 550 nm is less than 0.1% for in-plane measurements, while the relative standard uncertainty in the hemispherical reflectance of a white Spectralon sample at 560 nm is 0.27%.
Dynamic functional network connectivity analysis in schizophrenia based on a spatiotemporal CPD framework
Authors: Kuang Li-Dan , Li He-Qiang , Zhang Jianming , Gui Yan , Zhang Jin
Published: February 2024

Objective. Dynamic functional network connectivity (dFNC), based on data-driven group independent component (IC) analysis, is an important avenue for investigating underlying patterns of certain brain diseases such as schizophrenia. Canonical polyadic decomposition (CPD) of a higher-way dynamic functional connectivity tensor, can offer an innovative spatiotemporal framework to accurately characterize potential dynamic spatial and temporal fluctuations. Since multi-subject dFNC data from sliding-window analysis are also naturally a higher-order tensor, we propose an innovative sparse and low-rank CPD (SLRCPD) for the three-way dFNC tensor to excavate significant dynamic spatiotemporal aberrant changes in schizophrenia. Approach. The proposed SLRCPD approach imposes two constraints. First, the L1 regularization on spatial modules is applied to extract sparse but significant dynamic connectivity and avoid overfitting the model. Second, low-rank constraint is added on time-varying weights to enhance the temporal state clustering quality. Shared dynamic spatial modules, group-specific dynamic spatial modules and time-varying weights can be extracted by SLRCPD. The strength of connections within- and between-IC networks and connection contribution are proposed to inspect the spatial modules. K-means clustering and classification are further conducted to explore temporal group difference. Main results. 82 subject resting-state functional magnetic resonance imaging (fMRI) dataset and opening Center for Biomedical Research Excellence (COBRE) schizophrenia dataset both containing schizophrenia patients (SZs) and healthy controls (HCs) were utilized in our work. Three typical dFNC patterns between different brain functional regions were obtained. Compared to the spatial modules of HCs, the aberrant connections among auditory network, somatomotor, visual, cognitive control and cerebellar networks in 82 subject dataset and COBRE dataset were detected. Four temporal states reveal significant differences between SZs and HCs for these two datasets. Additionally, the accuracy values for SZs and HCs classification based on time-varying weights are larger than 0.96. Significance. This study significantly excavates spatio-temporal patterns for schizophrenia disease.
Noninvasive modulation of essential tremor with focused ultrasonic waves
Authors: Riis Thomas S , Losser Adam J , Kassavetis Panagiotis , Moretti Paolo , Kubanek Jan
Published: February 2024

Objective: Transcranial focused low-intensity ultrasound has the potential to noninvasively modulate confined regions deep inside the human brain, which could provide a new tool for causal interrogation of circuit function in humans. However, it has been unclear whether the approach is potent enough to modulate behavior. Approach: To test this, we applied low-intensity ultrasound to a deep brain thalamic target, the ventral intermediate nucleus, in three patients with essential tremor. Main results: Brief, 15 s stimulations of the target at 10% duty cycle with low-intensity ultrasound, repeated less than 30 times over a period of 90 min, nearly abolished tremor (98% and 97% tremor amplitude reduction) in 2 out of 3 patients. The effect was observed within seconds of the stimulation onset and increased with ultrasound exposure time. The effect gradually vanished following the stimulation, suggesting that the stimulation was safe with no harmful long-term consequences detected. Significance: This result demonstrates that low-intensity focused ultrasound can robustly modulate deep brain regions in humans with notable effects on overt motor behavior.
Critical and tricritical singularities from small-scale Monte Carlo simulations: the Blume–Capel model in two dimensions
Authors: Moueddene Leïla , G Fytas Nikolaos , Holovatch Yurij , Kenna Ralph , Berche Bertrand
Published: February 2024

We show that accurate insights into the critical properties of the Blume–Capel model at two dimensions can be deduced from Monte Carlo simulations, even for small system sizes, when one analyses the behaviour of the zeros of the partition function. The phase diagram of the model displays a line of second-order phase transitions ending at a tricritical point, then a line of first-order transitions. We concentrate on critical and tricritical properties and compare the accuracy achieved via standard finite-size scaling of thermodynamic quantities with that from the zeros analysis. This latter analysis showcases spectacular precision, even for systems as small as 64 spins. We also show that the zeros are very sensitive to subtle crossover effects.
Stretched exponential to power-law: crossover of relaxation in a kinetically constrained model
Authors: Mukherjee Sukanta , Pareek Puneet , Barma Mustansir , Kumar Nandi Saroj
Published: February 2024

The autocorrelation function in many complex systems shows a crossover in the form of its decay: from a stretched exponential relaxation (SER) at short times to a power law at long times. Studies of the mechanisms leading to such multiple relaxation patterns are rare. Additionally, the inherent complexity of these systems makes it hard to understand the underlying mechanism leading to the crossover. Here we develop a simple one-dimensional spin model, which we call a domain wall (DW) to doublon model, that shows such a crossover as the nature of the excitations governing the relaxation dynamics changes with temperature and time. The relevant excitations are DWs and bound pairs of DWs, which we term ‘doublons’. The diffusive motion of the DWs governs the relaxation at short times, whereas the diffusive motion of the doublons yields the long-time decay. This change of excitations and their relaxation leads to a crossover from SER to a power law in the decay pattern of the autocorrelation function. We augment our numerical results with simple physical arguments and analytic derivations.
The anisotropy behavior of metallic foams under Charpy impact tests
Authors: Galatanu Sergiu-Valentin , Linul Emanoil , Kováčik Jaroslav , Marsavina Liviu
Published: February 2024

Currently, the automotive industry is looking for their new products to have a density as low as possible so that CO2 emissions decrease. Metallic foams have attracted a great deal of interest in this industry because of their multiple advantages. They can be produced at a relatively low cost and have advantageous properties, especially due to their ability to absorb energy. In the framework of this study, 42 specimens were tested to determine the impact energy and Charpy impact strength according to the cutting orientation. Before being notched according to the ISO 148 standard, their specific mass was determined. For the tests, an Instron CEAST 9050 Charpy test machine was used. The impact strength was determined according to the cutting orientation, and the results obtained by the mass density groups were compared. It could be observed that the cutting orientation of the specimens does not have a clear influence on the impact strength; this is due to the irregular shape of the closed cell, however, the grouping of the specimens on specific density samples has influenced the impact strength.
Mechanical characterizations on biobased FMLs, being developed for battery boxes, before and after ageing
Authors: Mingazzini Claudio , Leoni Enrico , Bassi Stefano , Delise Tiziano , Scafe’ Matteo , Aloysio Giulia De , Laghi Luca , Morganti Mattia , Falleti Gian Luca
Published: February 2024

This paper reports the activities carried out under project FENICE (Upscaling, KAVA 9, EIT Raw Materials, www.Fenice-composites.eu, 2022-2025) about improving fire resistance of electric cars batteries, in particular through the development of Fiber Metal Laminates (FML) battery boxes. The aim of this study is to analyse the corrosion behaviour of FML based on bio-based and closed loop recyclable prepregs, in typical ageing conditions (thermal ageing, neutral and cupric acetic salt spray). FML degradation, evaluated in term of residual tensile strength after ageing, along with surface corrosion is remarkably low, and also resistance to humid environment seems satisfactory. However proper inorganic surface finishing is needed, since otherwise typical automotive tests, such as salty spray chamber ageing, cannot be passed in term of corrosion resistance requirements. The project is studying surface vitrification with sol-gel formulations, since traditional painting, based on organic polymers could ensure aluminium corrosion resistance, but would inevitably decrease fire resistance, while Cr-plating is not environmentally friendly, because of its higher carbon footprint and since it would make direct aluminium recyclability impossible, so. These advanced treatments were, up to now, not compatible with the adoption in the mass production, but things are rapidly changing, following the green transition that is currently bringing a number of small revolutions in the manufacturing sector.
Thermophysical characterization of innovative and recyclable composites, being developed and considered for battery boxes mass production
Authors: De Aloysio G , Morganti M , Laghi L , Ghetti L , Mingazzini C , Bassi S , Delise T , Leoni E
Published: February 2024

This paper describes the results of preliminary thermophysical characterization carried out on recyclable & biobased Fibre Metal Laminates (FML) for lighter, more sustainable & safer battery box production, with higher fire resistance. These FMLs are designed to be suitable for the low and medium end automotive. In particular, the specific heat and the thermal conductivity of four different types of FMLs were analysed and assessed depending on temperature. The results show increasing trends of specific heat by increasing temperatures and thermal conductivity values increasing both with temperature and the density of the samples. Further studies will be carried out both to optimise the composition of the FMLs and to provide extensive assessment of the thermal and mechanical properties of the solutions so as to guarantee high thermal and mechanical performances and durability of battery boxes for electric vehicles.
Properties of the crack resistance of layered composite and simulation of a crack quasi-static growth
Authors: Pavelko V
Published: February 2024

The outcomes of standard test of a carbon/epoxy layered composite using DCB specimen for measuring of the I-mode interlaminar fracture toughness (IFT) were analysed. Using the test results and earlier developed the model of quasi-static growth of crack (delamination) in layered composite, the investigation of variable properties of IFT was continued. It is shown that the use of stationary continuous functions for mathematical description of IFT does not allow to completely satisfy to the data of test. The simplest type of stationary discontinuous function is selected for analysis and simulation: the periodic piecewise-constant function. Using the model of quasi-static growth of crack and the mentioned type of variable IFT function the process of a crack propagation in DCB sample at quasi-static loading with control of displacement is simulated. Comparison of IFT function and the crack resistance (R-curve) together with other outcomes of simulation are the base of proposed procedure of variable IFT estimation from DCB Standard test.
Experimental verification of PEKK stiffened panel under compression
Authors: Růžek Roman , Karkulín Adam , Mlch Ivan , Mrňa Tomáš , Šedek Jakub
Published: February 2024

The paper presents the experimental strain and stress analysis of a thermoplastic composite stiffened panel subjected to compression load. The panel has five stringers with a non-symmetric design. Two panels are investigated. The experimental analysis deals with the pristine panel without any flaws and the panel with an artificial crack at the middle stringer interface with the skin. Panels were made from a thermoplastic polyetherketoneketone (PEKK) carbon composite. The buckling and mechanical analysis is based on digital image correlation, strain gauge measurements, and linear variable differential (LVDT) transducers. The crack subcritical extension was defined and analysed. The results show that crack propagation starts coupled with sudden buckling mode transition. The crack growth behaviour is influenced by the buckling shape, which consists of two main modes (with three and four half-waves) in the longitudinal direction in each skin bay.
On the strength of the piezoceramic transducer in the system of structural health monitoring
Authors: Pavelko I
Published: February 2024

The aim of the presented paper is the more detailed investigation and improvement of pre-stressing technology for the piezoelectrical transducer (PET) protection from degradation at action of extreme overload and longtime variable load in operation. Earlier developed 1D model of embedded PET is verified by the finite element analysis. Using this model, the parametrical assessment of stress state and strength of conventional transducer is done. It is shown that there is specific class of PET for which satisfying solution cannot always be obtained by optimization of parameters of the conventional piezoelectrical transducer (CPET). Therefore, further analysis is focused on the stress state and strength of the pre-stressed piezoelectrical transducer (PPET) it comparison with CPET. The electromechanical impedance (EMI) and its integral indicis are used for assessment of PET operability. Numerical simulation of EMI response to possible damages of PET and the outcome of static and fatigue tests are shown the significantly higher resistance of PPET against operational degradation in comparison with CPET.
Implementation of a Robotic Mobile Manipulator moving a NDT probe inside Steel Cylinder Concrete Pipes for Corrosion Assessment
Authors: Larbi Lucas Si , Lucet Eric , Zhang Chen , Kfoury Farès
Published: February 2024

This paper presents the full implementation of a mobile robotic manipulator moving a probe inside steel cylinder concrete pipes (SCCP) for corrosion assessment. Mechanical prototype based on an off-the-shelf mobile base and a custom-designed manipulator, control and monitoring software architecture, posture control and manipulation inside SCCP are presented. Simulations and testing under realistic operating conditions demonstrate a reliable solution providing repeatable results with high positioning accuracy.
Nano-scale characterisation, deformation and failure mechanisms on enhanced-performance modern steels
Authors: Kaldellis A , Makris N , Fourlaris G , Tsakiridis P
Published: February 2024

This research project aims to experimentally study the nature and fundamental characteristics of microstructure, deformation and failure mechanisms, focused on various and complex nanoscale phases, such as precipitations and paraequilibrium phases, not yet completely explained in modern nanophase steels by state-of-the-art literature. Moreover, this work focuses on the investigation of correlation of the microstructure with its impact on the mechanical properties in laboratory-developed novel nanophase steels, which mainly consist of a ductile ferrite matrix, and are strongly affected by appropriate alloy design and thermomechanical treatment differentiations. The microstructural investigation will be accomplished by Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), in conjunction with Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). Mechanical properties evaluation is assessed by hardness tests. The experimental approach has been designed based on the -nano to macro- examination of the materials under investigation to overall understand and explain their nature and properties. Finally, the outcome endeavours to interpret the nanophases’ influence as well as the contribution of alloying elements and thermomechanical and heat treatment routes on the microstructure-properties relationship of these novel nanophase steels.
Fatigue behaviour of 10% wt. short glass fibre reinforced recycled Polypropylene with mineral filler in presence of notches
Authors: Coppola F , Ricotta M , Garilli M , Fabbro L , Azzalin I , Meneghetti G
Published: February 2024

An experimental investigation of the fatigue behaviour of plain and notched specimens made of 10% wt. short glass fibre reinforced partially recycled Polypropylene filled with mineral filler is presented. To this end, plain and V-notched specimens (with notch radius ranging from 0.07 mm to 10 mm) were produced by injection moulding and tested under tension-tension fatigue. During the fatigue test, the damage evolution was monitored using a traveling microscope to define the number of cycles spent for the fatigue crack initiation. The fracture surfaces were analysed at microscopic level in order to investigate the fatigue damage mechanisms of plain and notched specimens. The fatigue tests were first analysed in terms of net stress amplitude to define the stress-life curves. Then, an energy-based approach was proposed to reduce the scatter of the fatigue data of plain and notched specimens. Starting from the damage evolution observed during the fatigue tests, the model relies on the strain energy density numerically evaluated in the matrix and averaged on a structural volume embracing the notch tip.
Random vibration-based progressive fatigue damage monitoring in thermoplastic coupons: a preliminary investigation
Authors: Tsivouraki N , Tserpes K , Fassois S
Published: February 2024

In recent years there has been an increasing trend towards the utilization of composites, particularly thermoplastics, in various components of aerostructures. The prelusion of such materials has underscored the significance of investigating their fatigue behavior and developing reliable methods for detecting fatigue damage. In this context, vibration-based techniques hold significant potential as they leverage the inherent excitation provided by in-flight noise and turbulence. This study aims at assessing the progressively accumulated fatigue damage in thermoplastic coupons via random vibration signals while accounting for operational and inter-structural uncertainties. The experimental process consists of preliminary tension and fatigue tests, interrupted fatigue tests, C-Scan inspection tests, and non-contact random vibration tests. Consecutive fatigue states are obtained by performing fatigue tests at intervals of 10 000 cycles for a population of 7 coupons. At each interruption, ultrasonic C-Scan and vibration inspection tests are performed, allowing for the visualization of fatigue damage and random vibration signal analysis. Welch Power Spectral Density estimates are employed and are shown to have good potential for distinguishing among different fatigue states despite the inevitable population and experimental uncertainty. Furthermore, fatigue damage is found to progress symmetrically and laterally along the free edges of the test coupons, which is explained by the free edge effect.
Fatigue strength assessment of preloaded cross-toothed flange connections based on the FKM guidelines
Authors: Härtel H. , Ulrich C. , Fiedler M. , Kästner M. , Schlecht B.
Published: February 2024

Cross-toothed flange connections are used in drivetrains for form-fit coupling of shafts. They belong to the group of non-shiftable couplings. Compared to frictional connections, tooth flange connections can transmit significantly higher torques in the same space. In contrast to other tooth couplings, the crossed tooth flange coupling investigated here is characterized by a particularly complex load distribution. The preload force, which is necessary to transmit operational loads, is generated by tensioning bolts, which can be located centrally or decentralized. Thus, the stress condition in the notch of the coupling is always determined by a superposition of stresses from preload force and operating loads.

Extensive experimental and simulative investigations were carried out as a part of a research project. In addition to the development of a pragmatic, specially adapted calculation concept for cross-toothed couplings for practice, the experimental tests were accompanied by calculations with the FKM guideline “Analytical Strength Assessment” and the FKM guideline “non-linear”, The determination of local stresses was carried out with the help of elasticity theoretical and elastic-plastic FE full-contact calculations based on experimentally determined material data.

This article deals with the possibilities of calculations based on the FE simulation results using the above mentioned FKM guidelines. The experimentally determined load-carrying capacity is critically compared to the calculation results. The focus is on the implementation of the fatigue strength analysis in the context of the corresponding boundary conditions. Topics such as the assumed knee point of the Wöhler curve to the fatigue strength range are discussed as well as the evaluation options for elastic-plastic FE results for the guideline „non-linear”.
Notch approximation methods for components under thermomechanical stresses
Authors: Hamacher Jan , Kraft Jan , Vormwald Michael
Published: February 2024

In this paper two different kinds of notch approximation methods are presented. The proposed methods are known as the incremental notch approximation method (e. g. Neuber method [1] or ESED [2, 3]) and the structural yield surface approach (SFF) (after Köttgen et al. [3]), while two different approaches of the SFF are used. All methods are capable to handle multiaxial cyclic loading. For a validation, the methods are compared to the results of a finite element analysis (FEA) of a notched component. The presented comparison is made for a non-proportional loading case. One objective of the work is to find out, which is suitable to extend it to thermomechanical loads as a next step.
Wear and Friction Behaviour of Additive Manufactured PEEK under Non-conformal Contact
Authors: Chen Y K , Lin G B , Shukur Z M , Kukureka S N , Dearn K D
Published: February 2024

Tribological properties of laser sintered polyether-ether-ketone (EOS PEEK HP3) were investigated using a rolling-sliding test rig. This investigation aimed to study the wear and friction failure mechanism of EOS PEEK HP3. The main objectives included to conduct wear and friction tests under non-conformal contact, to monitor surface temperature, to carry out surface characterization with microscopy. With this rolling-sliding test rig, tests were carried out on an EOS PEEK HP3 specimen running against a steel disc unlubricated, with various slip-ratios under a contact pressure of 56 MPa, 48 MPa and 39 MPa respectively. Both wear and friction were measured. The results have shown that both friction and wear were increased with an increase of either slip-ratios or the contact pressures, exacerbated by high surface temperatures. It has also been observed that both friction and wear failures were associated with the degradation of the non-conformal contact surfaces due to crystallinity changes that correlated well with working conditions. Using microscopy it was found that such failures as pitting, fatigue and surface cracking were affected by the surfaces in contact, including the degree of melting of the surface. Based on the observation on the contact surfaces, the failure mechanisms of EOS PEEK HP3 include surface melting and contact fatigue failures with the high slip-ratio and the high contact pressure conditions. The findings of this investigation have the potential to help to design & develop additive manufacturing PEEK products. Typically, these results can be used in a design process for a more effective polymeric gear system.
Bird strike analysis of new composite inlet for tilt rotor aircraft
Authors: Doubrava R , Vlach J , Oberthor M , Bělský P
Published: February 2024

Bird strikes are an important phenomenon to consider when designing and servicing aircraft structures. Most major bird strike incidents result in aircraft propulsion damage. Because an engine is the sole thrust-providing system of an aircraft, the effect of bird strikes on engine inlets and systems must be investigated and mitigated to the maximum extent. Especially in the case of (vertical take-off and landing) VTOL aircraft, such as an aircraft with tilting rotors, this effect is critical from the point of view of the operation, from the point of view of flight mechanics and the overall control of the aircraft. This work aims to propose the proof of resistance of a new composite air inlet for a new tilting rotor aircraft, which is experimentally verified and supported by numerical simulations performed on flat and simple curved test panels. The new, very effective method was used to calibrate the composite material model, which is further used in the following numerical simulations.
Overview of the V International Conference on Applied Physics, Information Technologies and Engineering - APITECH-V 2023
Authors: Siddikova Sadokat , Yuldashev Narbek , Juraeva Malokhat , Abrorov Akbar , Kuvoncheva Matluba
Published: February 2024

The overview describes the main directions and results of the V International Conference APITECH-V 2023 held in Bukhara, Uzbekistan on 26-28 October 2023. It gives the details about the participants and the proceedings. The purpose of the Conference is to share the experience of leading experts in the application of modern methods of applied physics and information technology in high-tech production, in the fields of aerospace, energy, chemical and oil and gas engineering.

List of International Programme Committee is available in the Pdf.