bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing sparse regression modeling of hysteresis with optimized PIO algorithm in piezo actuator
Authors: Jin Yu , Yu Jianbo , Xu Yunlang , Lu Qiaodan , Yang Xiaofeng 
Published: February 2024

Abstract
The extensive application of piezo actuators is attributed to their high responsiveness and ability to achieve nanoscale steps. However, the accuracy and stability of motion are seriously affected by hysteresis caused by nonlinear characteristics. In this paper, a pigeon-inspired optimization (PIO) algorithm based on dynamic opposite learning (DOL) is proposed to address the issue of nonlinear modeling accuracy in piezo actuators by integrating the sparse identification of nonlinear dynamics (SINDy) method. Firstly, the DOL strategy is employed to introduce reverse pigeon flock into the PIO algorithm, thereby enhancing population diversity and optimization performance. Secondly, through combining the DOLPIO algorithm with the SINDy algorithm, sparse optimization for the penalty process in SINDy algorithm is conducted and the sparse coefficient is optimized based on modeling accuracy. Thirdly, the DOLPIO algorithm is utilized again to optimize the framework of optimized sparse penalty model in order to improve overall modeling accuracy. Finally, experiments are conducted on an established platform to validate the effectiveness of this algorithm.
Dynamic measurement of ballistic impact using an optical fibre sensor
Authors: Velasco Ivann , Seng Frederick , Hodges Greyson , Peters Kara , Pankow Mark , Schultz Stephen 
Published: February 2024

Abstract
An optical fibre-based sensor is developed for measuring the dynamics of the back face deformation of soft body armor. The measurement system consists of embedding an optical fibre into a thin silicone mat to increase survivability. The silicone sensor mat is placed between the soft body armor and the backing material. The optical fibre experiences times of sticking and slipping. The portions of the impact with the optical fibre stuck are reconstructed into slipping-equivalent strain using exponential extrapolation from adjacent slipping portions. The strain on the optical fibre is related to the projectile acceleration when the optical fibre is slipping. The strain is measured with the optical fibre sensor using a fibre Bragg grating. The system is characterized using a gas gun in combination with high-speed imaging. The system is experimentally demonstrated at the Army Test Center in Aberdeen, MD. Of the 23 shots 17 had an error less than 10%.
Generalization of Gisin’s theorem to quantum fields
Authors: Schlichtholz Konrad , Markiewicz Marcin 
Published: February 2024

Abstract
We generalize Gisin’s theorem on the relation between the entanglement of pure states and Bell non-classicality to the case of mode entanglement of separated groups of modes of quantum fields extending the theorem to cover also states with undefined particle number. We show that any pure state of the field which contains entanglement between two groups of separated modes violates some Clauser–Horne (CH) inequality. In order to construct the observables leading to a violation in the first step, we show an isomorphism between the Fock space built from a single-particle space involving two separated groups of modes and a tensor product of two abstract separable Hilbert spaces spanned by formal monomials of creation operators. In the second step, we perform a Schmidt decomposition of a given entangled state mapped to this tensor product space and then we map back the obtained Schmidt decomposition to the original Fock space of the system under consideration. Such obtained Schmidt decomposition in Fock space allows for construction of observables leading to a violation of the CH inequality. We also show that our generalization of Gisin’s theorem holds for the case of states on non-separable Hilbert spaces, which physically represent states with actually infinite number of particles. Such states emerge, for example, in the discussion of quantum phase transitions. Finally, we discuss the experimental feasibility of constructed Bell test and provide a necessary condition for realizability of this test within the realm of passive linear optics.
A step towards the diagnostic of the ITER first wall: in-situ LIBS measurements in the WEST tokamak
Authors: Favre Aurélien , Bultel Arnaud , Lamine Sankhe Mamadou , Vartanian Stéphane , Bruno Vincent , Morel Vincent , L’Hermite Daniel , Sirven Jean-Baptiste , Diez Mathilde , Missirlian Marc , Magaud Philippe , Grisolia Christian 
Published: February 2024

Abstract
As part of the development of proven diagnostics allowing the characterization of ITER’s PFUs (Plasma Facing Units) without dismantling, LIBS (Laser-Induced Breakdown Spectroscopy) is a serious candidate for determining the multi-elemental composition. In this article, we report a measurement campaign carried out within the WEST tokamak using an original device based on the following technological choices. (1) The laser source and the spectrometer are placed outside the tokamak. (2) The laser pulses are conveyed by an optical fiber. (3) The signals are collected by a second optical fiber. (4) The optical focusing and collection device is placed in the desired location by a remote handling arm (AIA, Articulated Inspection Arm). The processed signals allow the measurement of the composition of the irradiated material. The technological choices are discussed in the light of their implementation and proposals are made for a more efficient future version of the system.
Galaxy bias in the era of LSST: perturbative bias expansions
Authors: Nicola Andrina , Hadzhiyska Boryana , Findlay Nathan , García-García Carlos , Alonso David , Slosar Anže , Guo Zhiyuan , Kokron Nickolas , Angulo Raúl , Aviles Alejandro , Blazek Jonathan , Dunkley Jo , Jain Bhuvnesh , Pellejero Marcos , Sullivan James , Walter Christopher W. , Zennaro Matteo ,   The LSST Dark Energy Science collaboration
Published: February 2024

Abstract
Upcoming imaging surveys will allow for high signal-to-noise measurements of galaxy clustering at small scales. In this work, we present the results of the Rubin Observatory Legacy Survey of Space and Time (LSST) bias challenge, the goal of which is to compare the performance of different nonlinear galaxy bias models in the context of LSST Year 10 (Y10) data. Specifically, we compare two perturbative approaches, Lagrangian perturbation theory (LPT) and Eulerian perturbation theory (EPT) to two variants of Hybrid Effective Field Theory (HEFT), with our fiducial implementation of these models including terms up to second order in the bias expansion as well as nonlocal bias and deviations from Poissonian stochasticity. We consider a variety of different simulated galaxy samples and test the performance of the bias models in a tomographic joint analysis of LSST-Y10-like galaxy clustering, galaxy-galaxy-lensing and cosmic shear. We find both HEFT methods as well as LPT and EPT combined with non-perturbative predictions for the matter power spectrum to yield unbiased constraints on cosmological parameters up to at least a maximal scale of k
max = 0.4 Mpc-1 for all samples considered, even in the presence of assembly bias. While we find that we can reduce the complexity of the bias model for HEFT without compromising fit accuracy, this is not generally the case for the perturbative models. We find significant detections of non-Poissonian stochasticity in all cases considered, and our analysis shows evidence that small-scale galaxy clustering predominantly improves constraints on galaxy bias rather than cosmological parameters. These results therefore suggest that the systematic uncertainties associated with current nonlinear bias models are likely to be subdominant compared to other sources of error for tomographic analyses of upcoming photometric surveys, which bodes well for future galaxy clustering analyses using these high signal-to-noise data.
Primordial Black Holes and loops in single-field inflation
Authors: Firouzjahi Hassan , Riotto Antonio 
Published: February 2024

Abstract
Using the δN formalism we calculate the one-loop correction to the large-scale
power spectrum of the curvature perturbation in the standard scenario where primordial black holes
are formed in the early universe thanks to a phase of ultra-slow-roll in single-field
inflation. We explicitly show that one-loop corrections are negligible when the transition from
the ultra-slow-roll to the slow-roll phase is smooth. We conclude that the PBH formation scenario
through a ultra-slow-roll phase is viable.
Mechanism of hydrogen isotope exchange for tritium removal in plasma-facing materials: a multi-scale investigation
Authors: Sun F. , Hao C. , Chen D.Y. , Zhou H.S. , Oya Y. , Zhu J.P. , Tang J. , Zong H. , Luo L.M. , Wu Y.C. 
Published: February 2024

Abstract
The safety of future fusion reactors is critically dependent on the tritium (T) retention in plasma-facing materials. Hydrogen isotope (HI) exchange offers a method to redistribute HIs within solid materials, presenting a feasible approach for removing T from bulk materials and trapped by strong trapping sites. Nonetheless, unraveling the intricate mechanism behind HI exchange remains an urgent yet formidable challenge. This study undertakes a comprehensive investigation into the mechanism of HI exchange in tungsten materials across multiple scales. First, we developed a multi-component hydrogen isotope transport and exchange model (HIDTX) based on classical rate theory. The model validation was further carried out, demonstrating good consistency with the well-controlled laboratory experiments. From the results of different comparative models in HIDTX, it is found that the reduction in deuterium retention due to HI exchange was primarily driven by three synergistic effects: competitive re-trapping, collision, and swapping effects. Through molecular dynamics (MD) and first-principles calculations, the microscopic mechanism of HI exchange was revealed to be that the presence of hydrogen atoms in the interstitial sites surrounding a vacancy in tungsten decreased the binding energy between the vacancy and hydrogen. Meanwhile, we discovered that the combination of thermal desorption and HI exchange can significantly lower the temperature required for the hydrogen removal and enhance the removal rate. Particularly, the hydrogen removal time can be shortened by approximately 95% with simultaneous HI exchange compared to that with only thermal desorption. This work provides a practical guideline for comprehending and subsequently designing for efficient T removal in future nuclear fusion materials.
Simulation of the degraded (steel - concrete) bond strength due to corrosion via modeling pull out tests
Authors: Koulouris Konstantinos , Charalampopoulos Alkiviadis , Apostolopoulos Charis 
Published: February 2024

Abstract
Steel corrosion is recognised as major degradation factor of structural capacity and durability of reinforced concrete (RC) structures, especially in marine environment. RC structures with corroded reinforcement present reduced performance due to loss of the cross-sectional area of reinforcement, cracks in concrete and loss of bond between steel and the surrounding concrete. In the present study, simulation of the degraded bond strength on corroded RC elements was elaborated developing a three-dimensional (3D) model through finite element analysis (FEA) in ABAQUS, taking into account the recommendations of fib Model Code 2010. As a basis for the model validation, an existing experimental study on the effect of corrosion and stirrups spacing on bond behavior was considered. In the abovementioned study the bond mechanism of two groups of corroded RC specimens in confined (stirrups Φ8/120mm) and unconfined (without stirrups) conditions were examined upon the completion of eccentric pull-out tests. In order to model the complex conditions of the corroded steel-concrete interface, the cohesive behavior was adopted by appropriately modificated parameters, for each corrosion level. The bond-slip curves extracted from the developed model were shown to be in a good agreement with the relevant experimental results. In particular, the bond strength of confined RC specimens deviates at about 10% among the analytical and experimental outcomes, for both uncorroded and corroded conditions up to 8.3% corrosion level. In case of the unconfined specimens, the bond strength prediction was satisfactory up to 5% corrosion level, whereas for greater corrosion level, large deviation was observed. Regarding the prediction of the relative slip between steel and concrete, further investigation is required as the development of slip is influenced by a plethora of factors.
Thick Film Sensor Manufacturing Techniques for Realization of Smart Components via Low Pressure Die Casting
Authors: Lehmhus Dirk , Cen Marco , Struss Adrian , Rijk Tim de , Pille Christoph , Lang Walter 
Published: February 2024

Abstract
Recent developments like autonomous driving have increased the interest of the automotive industry in structural health and condition monitoring of safety-relevant components often manufactured via High or Low Pressure Die Casting (HPDC, LPDC). Specifically the latter process is important in this field as the improved quality of castings produced facilitates T6 heat treatments aimed at optimizing mechanical performance of such components. The specific challenge associated with this approach is that it produces critical thermal loads which may compromise the characteristics of the integrated sensor. The present study shows the results obtained by LPDC on thick film sensor systems prepared by means of screen printing on aluminum substrates. The response of the sensor systems to the thermal loads associated with the casting process is evaluated in casting experiments, with temperatures reached during casting checked by means of thermocouples attached to the inserts. The focus is on the influence on general properties of the piezoresistive sensors as well as on their response to thermal and mechanical stimuli. The results show that in contrast to HPDC, in the case of LPDC, the former provides stimuli for thermally induced processes which can compromise sensor layers. The respective trends have been studied via resistance measurements on samples subjected to repeated firing cycles and actual casting experiments.
Morphological and functional characterization of electroplated Ni-graphene composite coatings
Authors: Almonti Daniele , Baiocco Gabriele , Millia Massimiliano Della , Mingione Emanuele , Menna Erica , Rubino Gianluca , Salvi Daniel , Stamopoulos Antonios , Ucciardello Nadia 
Published: February 2024

Abstract
Composite coatings (CECs) are providing a unique technological advantage for improving mechanical and tribological surface properties. Among different methods, electrodeposition is one of the most exploited to produce composite surface coatings on metal substrates. However, the process parameters affect graphene distribution, coating morphology and performance. This paper investigates how different deposition conditions influence the inclusion of large Graphene nanoplates (GnPs) in a Nickel matrix and the coating morphology and tribological performance. Set the process condition such as electrical parameters and the galvanic bath, the work focuses on the stirring rate effect. To this end, Ni-GnP coatings were obtained by a laboratory setup and evaluated through surface profilometry, SEM characterization and a dry-sliding linear reciprocating wear test. The results highlight the influence of stirring on coating uniformity. The low stirring rate allows larger particles to be embedded, which are not thoroughly covered; however, they act as a solid lubricant and reduce the friction coefficient.
Ageing Behavior of Rubber Compounds Prepared with Different ZnO Types
Authors: Börüban Bingöl C , Polat Ş , Atapek Ş H 
Published: February 2024

Abstract
Zinc oxide is considered as the most widely used activator that influences curing reaction kinetics and promotes short sulphide crosslinks to achieve higher crosslink density in rubber compounds. Besides its effect on curing process, it has beneficial effects on the physical and mechanical properties of rubber as well. However, its level should be minimized in rubber compounds because of its toxicity for human health and environment, especially on aquatic wildlife. One of the potential routes for decreasing ZnO level is to use composite ZnO materials where ZnO particles are coated. In this study, composite ZnO materials having ZnO:CaCO3 ratio as 40:60, 60:40 and 90:10 are used in SBR/BR compounds and their effects on mechanical properties under ageing conditions are investigated and compared with the conventional white seal ZnO and active ZnO types. The findings have shown that all composite materials have no negative effect on mechanical properties under ageing conditions, thus they can be used as alternative materials to conventional activators.
Improving the mechanical properties of Glass Reinforced Plastics by slight mechanical compression
Authors: Iakovidis I , Dimitrellou S , Orfanos G , Vlachogiannis M 
Published: February 2024

Abstract
Glass reinforced plastics (GRPs) are composite materials that have been used widely in engineering. Mechanical properties of fabricated GRP products depend on the type and arrangement of reinforcement, the type of the plastic as well as the reinforcement to plastic ratio. Some of these factors are interdepended in determining the quality of the final product. In the present study, the influence of applying mechanically a slight pressure during fabrication on the properties of GRP specimens, was investigated. Specimens were fabricated using the hand lay-up method and were further processed either by a vacuum bag compression or a mechanically applied pressure. The properties of the produced composite specimens were then determined experimentally. The application of mechanical compression was found to improve their properties. The effect of the mechanically applied compression or vacuum was evident as a reduction of the specimens’ internal void volume compared to the non-compressed ones, resulting in an increase in the density by 9–12% and a reduction in the thickness of the specimens by 15–20%. Additionally, the tensile and flexural strength of the specimens were increased by more than 15% and 5% respectively when pressure was applied mechanically, reflecting an improvement in GRPs’ mechanical properties.
Development and experimental validation of a prototype system for Machine Learning based SHM in composite aerostructures
Authors: Spiliotopoulos P E , Fera F T , Saramantas I E , Sakellariou J S , Fassois S D , Ofir Y , Kressel I , Tur M , Papadopoulos P , Giannopoulos F , Spandonidis C 
Published: February 2024

Abstract
The development and experimental validation of a Machine Learning (ML) vibration based Structural Health Monitoring (SHM) prototype system for composite aerostructures operating under uncertainty is presented. Following initial training, it is intended to operate autonomously, in almost real-time, without interrupting normal operation, relying on a limited number of acceleration and strain measurements from properly selected locations on the aerostructure. It is equipped with a multi-level information fusion methodology comprising multiple sensor technologies and diagnostic algorithms for optimized SHM performance in terms of damage detection and characterization. Through its flexible software, the system provides multiple options of ML based SHM methods targeting wide applicability to various types of structures. The system is validated based on numerous experiments with healthy and damaged full-scale composite bonded spars operating under multiple uncertainty factors. Its diagnostic performance indicates that the current progress in hardware and robust vibration-based Machine Learning algorithms may lead to compact, effective, and low cost SHM systems for composite aerostructures under normal operating conditions.
Fatigue Life Assessment of Automotive Leaf Springs
Authors: Giannakis E , Savaidis G 
Published: February 2024

Abstract
The creation of a new mechanical component, such as a high-performance leaf spring, is a very challenging procedure that consists of many stages over a long timeframe from concept to production. High performance leaf springs are components with high complexity at the areas of failure. This complexity is derived from the multiple manufacturing processes that the raw material undergoes to reach its final geometrical and microstructural form. The paper shows the assessment of fatigue life of high-performance leaf springs, from different manufacturers with different geometrical and loading parameters. The assessment uses the fatigue life calculations which are described at the FKM Guideline as a basis. Limitations of the FKM Guideline, concerning the material’s ultimate tensile strength and the exclusion of the stress shot peening process, are restricting the fatigue life calculations of such components, therefore, a new theoretical tool is needed for more accurate calculations.
NAVMAT: an AI-powered pathway to knowledge sharing on material failures
Authors: Melanitis N , Giannakopoulos G , Stamatakis K 
Published: February 2024

Abstract
The paper describes the product development methodology, the architecture, the modules and features of the operating prototype, as well as future challenges of NAVMAT, a naval materials failure management system. The fundamental compound of the knowledge management platform is the recording and classification of a failure incident. NAVMAT supports different types of users, from the first Reporter to the Analyst and Forensic Engineer through appropriate workflows. In these workflows the incident-related information can be provided as text, files, images and videos, which can be easily associated to the incident and provide structured information. NAVMAT provides a number of Artificial Intelligence (AI)-enabled helpers. During the incident recording, NAVMAT brings into play reactive real-time search which suggests related incidents and literature to facilitate the editor. It also speeds up the classification of incidents by providing AI-suggested labels, chosen from the (multi-lingual) concepts contained in the system Ontology. On the other hand, the intelligent indexing and search infrastructure of the system supports easy identification and retrieval of past incidents, reports and publications, by applying Natural Language Processing. The prototype of the described system has been embedded as a web application validated by potential Users and is being prepared for Operation in a fleet environment.