bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal-structural Modeling of power electronic package: effects of deposition geometry and dry spot on the stress distributions
Authors: Mirone Giuseppe , Barbagallo Raffaele , Bua Giuseppe , Sitta Alessandro , Calabretta Michele , Sequenzia Gaetano 
Published: May 2024

Abstract
A Power Electronics package is a heterogeneous system made of semiconductor devices (dies), metallic-ceramic substrate, baseplate and encapsulating material.
The electronic devices can be MOSFETs (Metal Oxide Semiconductors Field Effect Transistors), diodes, IGBTs (Insulated Gate Bipolar Transistors) and passive components such as capacitors, resistors and sensors integrated on support circuit; the complete set of semiconductor devices installed on a package form the so-called “power modulus”.
These devices play an important role in the transmission and conversion of energy in electric and hybrid vehicles. Due to the elevated currents and, consequently, the elevated temperatures at which these systems work, and due to the mismatch of the thermal-mechanical properties of the materials from which they are made, stresses and strains develop within the devices.
Such stresses can be locally concentrated and amplified, depending on the deposition geometry of the various layers constituting the semiconductor device. Edge termination structures are essential to decrease the electric field at die’s edges, and, including brittle compounds in their composition, like Si3N4 or SiO, they are quite sensitive to mechanical stress.
Another reason that may cause the stresses concentrations is the presence of dry spots. Dry spots are areas of various size, located at the interface between die or leadframe and the encapsulating resin, where there is a total or partial lack of adhesion.
The aims of this work are, mainly, two. At first, four linear finite element analyses have been performed in order to evaluate the stresses concentrations at the corners of edge termination structure.
The first case concerns sharp corners and the other cases concern differently filleted corners. In the second part of this work, it has been analysed the dry spot effect on stress distributions. Due to the small size of the defect with respect to the whole package, a Global-Local FEM approach has been used, creating a local subdomain where the mesh is denser than the global domain and a running a further separate numerical analysis which takes its boundary conditions from the global analysis, so delivering reliable small-scale stress and strain gradients. This approach permits to achieve accurate analyses focused on zones of interest of the global domain, limiting the increase of the computational cost of the modelling.
Multimethodology based on Design-to-Value (DtV), integrated with simulation techniques and prioritization of teamwork for the optimization of a pneumatic rack & pinion actuator
Authors: Maiocchi G , Vigliano L , Nicoletto G 
Published: May 2024

Abstract
The investigations here presented focus on the redesign and innovation of a pneumatic rack and pinion actuator for valve actuation, as a case study for investigating the potential of a multimethodology based on the Design to Value (DtoV) process, coupled with design techniques utilizing FEA simulations and giving high priority to teamwork. The final objective of this case study is to show how it is possible to optimize the design, increasing weight efficiency while maintaining performance, and to simplify it, with a reduction of components construction complexity, according to the growing demand for a lean production. The principle that guided all the activities was valorizing the power of teamwork, focusing the team on Safety and Reliability. In an initial phase, all the instruments foreseen by “Design-to-Value” process have been applied, obtaining a classification of the contents of the product constituting its sources of value. Subsequent outputs are proposals for efficient construction solutions, driving a second phase, dedicated to the re-design of the actuator. The peculiarity of this project has been to combine the “Design by Formulas” techniques with advanced FEA simulations (“Design by Analysis”), aiming to stress, deformation, and topology optimization. A two-step experimental validation is used, based on a preliminary “mockup” prototype followed by a complete detailed prototype, for confirming the results of the calculations and simulations, by directly performing a series of in-depth tests. Preliminary obtained results show that the approach based on the described multimethodology, makes it possible to optimize the design of the actuator, maintaining safety, reliability, and performance. In the case studied, the weight reduction is expected to be 8% and economic efficiency increase is expected to be near 20%.
FMEA, monitoring, retrofit and redesign of insulated rail joints
Authors: Bracciali A , Megna G 
Published: May 2024

Abstract
Insulated rail joints (IRJ) are a fundamental component of railway signalling that ensure train protection using “track circuits”. A track circuit is a section of line delimited by rail joints electrically insulated, powered at one end with an electric power supply to establish a different voltage that is checked at the other end with a so-called “track circuit relay”. When the section is short-circuited by an axle the relay drops, and the section is defined as “occupied”. IRJ are subjected to continuous and dangerous failures as they represent a singularity in the rail continuity. Continuous battering produces the classical train impact noise while damage in the rail accumulates until the IRJ fails with extremely unpleasant consequences. The paper discusses the main failure modes of an IRJ starting from a historical perspective, showing how an appropriate failure analysis would have prevented a catastrophic accident that recently occurred in Italy. Several countermeasures are shown and a completely new IRJ potentially completely solving the issue is introduced.
Structural and dynamic assessment of a friction buffer stop
Authors: Megna G , Bracciali A 
Published: May 2024

Abstract
Under peculiar conditions railway braking system ca fail giving insufficient braking force during train ride or while standstill and buffer stops are used to avoid derailments at the end of railway tracks (dead tracks). Fixed stops are suitable only for quasi-static movements, while absorbing energy stops using hydraulic cylinders, friction shoes clamped on the rail head or a combination of both methods, are installed if crashes at higher speeds (about 25 km/h) are forecasted. Impact forces generated due to the interaction between train and buffer stops require a suitable design of the steel structure which is subjected to stress values depending on the braking performances of the buffer stop itself and a combined structural and dynamic analysis must be carried out to perform a proper design. Due to unavailability of detailed models and the uncertainties of the actual braking performances, the structure of currently available friction buffer stops is heavy and bulky, made of several steel profiles welded or bolted to each other. The paper describes an innovative and optimized design for friction buffer stops focusing on the dynamic analysis performed by Finite Element Method to assess the braking performances and structural strength of the buffer stop.
Stress mitigation of a thermal engine head block using the bioinspired BGM-FEM method
Authors: Groth C , Marra M , Porziani S , Schubert M , Biancolini M E 
Published: May 2024

Abstract
Structural optimization plays a pivotal role in the design and development of engine heads, as it directly affects the performance, efficiency, and durability of internal combustion engines. In this paper, we propose a novel approach for the thermo-structural optimization of the internal surfaces of the engine heads, using the Biological Growth Method (BGM). The BGM is a bio-inspired technique that mimics the growth patterns observed in some biological organisms, able to achieve superior structural efficiency thus generating optimal designs. The effectiveness of the BGM methodology, coupled with mesh morphing techniques based on Radial Basis Functions (RBF), is in this work demonstrated for several districts, effectively reducing material usage and enhancing structural performance.
Parametric Analysis on the Static and Modal Response of Folded Metamaterials
Authors: Santucci P.M. , Baldi A. 
Published: May 2024

Abstract
Metamaterials have been studied and analyzed in the past three decades because of their outstanding properties. Generally speaking, a metamaterial is a material that exhibits a mechanical behavior that does not depend only on the bulk material but also on the geometrical configuration in which it lies. This aspect leads to the possibility of tuning and engineering the structural response. One of the most interesting properties is the auxetic behavior of metamaterial. An auxetic material shows a global negative Poisson’s ratio. Shock absorption, acoustic dissipation, and shape morphing are some of the most popular employment for auxetic materials. In this article, we focus on the response of folded material under static and dynamic load conditions. Folded materials consist of folding a sheet under specific geometrical constraints. One of the most famous is the Miura-ori pattern, which comes from the origami-folding technique. The geometrical parameters, such as folding angles and edge lengths, play a fundamental role in achieving the desired auxetic behavior. These geometrical parameters define a unit cell that can be stacked into a periodic structure. This article proposes an experimental parametric study of the thickness impact on the auxetic behavior while edge dimensions and folding angles are fixed. The geometrical complexity of the pattern forced us to use additive manufacturing for the specimen fabrication. In particular, we choose Fused Filament Fabrication (FFF) using polymers like ABS and PLA. Digital Image Correlation (DIC) is used for monitoring the displacement and strain fields onto the Miura-ori surface under tensile load. Finally, Time Averaged Speckle Interferometry is employed for evaluating the modal response by using a quasi-full out-of-plane sensitivity setup.
Homogenized Stiffness Matrix of Two-Node Elements through Experimental Flexibility tests
Authors: Iandiorio C , Cafolla F , Marotta E , Salvini P 
Published: May 2024

Abstract
Homogenization is a numerical technique to obtain the equivalent mediated response of a complex material. However, there are some scenarios in which the complexity of the physical phenomena present in the real structure makes it difficult to generate a faithful Representative Volume Element (RVE). In these cases, it may turn easier and more reliable to perform a homogenization directly by experimental test results. For this reason, we present a procedure to build-up the whole stiffness matrix starting from experiments. This approach is here discussed to get a homogenised two-node beam element. The procedure requires some flexibility measurements, thus allowing fewer measurements if compared to stiffness-based approach. The method is verified with some experiments carried on a frame structure. The comparisons with a Finite Element model build up with stiffness matrix assembly demonstrates the validity and robustness of the proposed procedure.
Photoexcited charge carrier dynamics and electronic properties of two-dimensional MXene, Nb2CT
x
Authors: Fitzgerald Andrew M , Sutherland Emily , El-Melegy Tarek Ali , Hassig Mary Qin , Martin Julia L , Colin-Ulloa Erika , Ngo Ken , Grimm Ronald L , Uzarski Joshua R , Barsoum Michel W , Deskins N Aaron , Titova Lyubov V , Friedman Kateryna Kushnir 
Published: May 2024

Abstract
Two-dimensional, 2D, niobium carbide MXene, Nb2CT
x
, has attracted attention due to its extraordinarily high photothermal conversion efficiency that has applications ranging from medicine, for tumor ablation, to solar energy conversion. Here, we characterize its electronic properties and investigate the ultrafast dynamics of its photoexcitations with a goal of shedding light onto the origins of its unique properties. Through density functional theory, DFT, calculations, we find that Nb2CT
x
is metallic, with a small but finite DOS at the Fermi level for all experimentally relevant terminations that can be achieved using HF or molten salt etching of the parent MAX phase, including –OH, –O, –F, –Cl, –Br, –I. In agreement with this prediction, THz spectroscopy reveals an intrinsic long-range conductivity of ∼60 Ω−1 cm−1, with significant charge carrier localization and a charge carrier density (∼1020 cm−3) comparable to Mo-based MXenes. Excitation with 800 nm pulses results in a rapid enhancement in photoconductivity, which decays to less than 25% of its peak value within several picoseconds, underlying efficient photothermal conversion. At the same time, a small fraction of photoinjected excess carriers persists for hundreds of picoseconds, and can potentially be utilized in photocatalysis or other energy conversion applications.
Effect of adsorption interactions of Arabic gum with cement
Authors: B Sugumaran , Neme Ibsa 
Published: May 2024

Abstract
This study seeks to investigate the influence of cement and Arabic gum on the physico-mechanical and microstructural properties of cementitious composites. The influence of varying quantities of Arabic gum on the hydration, fluidity, mechanical performance and microstructure of cement paste was investigated. The influence of Arabic gum on slant shear performance and capillary water absorption was also investigated. The results indicate that the workability of cement was diminished as a result of the ability of Arabic gum to make the cement paste cohesive. It is evident that when the gum Arabic concentration increases from 147 to 174 mm, the resultant slump value for various w/b ratios drops. The adsorption characteristics showed that for a 15 mg g−1 dosage at 60, 45, 30, and 15 min, respectively, 1.43, 1.32, 1.25, and 1.03 mg g−1 are achieved. For 1% gum Arabic substitution, the highest flexural strength percentage growth is achieved at 38.46%, 23.74%, and 17.29% at 7, 14, and 28 days, respectively. In addition, the inclusion of Arabic gum improved the slant shear strength of cement composite, making it ideal for use as a building repair material with significant application potential. Experiments on the bonding behavior of the produced cementitious composite with the old mortar reveal that the shear bond strength was greatly increased, demonstrating the compatibility between the old and new cement composites. The microstructure and the porosity of the cement matrix also showed denser and compact matrix making them durable to attain better service life.
Additively manufactured microstrip patch antennas in flat, curved, and embedded configurations
Authors: Gurusekaran Arvind , Ahmad Mukhtar , Ciocca Manuela , Pompilio Michele , Nijkoops Annelot , Carrasco Pena Alejandro , Lugli Paolo , Petti Luisa 
Published: May 2024

Abstract
Microstrip patch antennas (MPAs) are compact and easy-to-fabricate antennas, widely used in long-distance communications. MPAs are commonly fabricated using subtractive methods such as photolithographic etching of metals previously deposited using sputtering or evaporation. Despite being an established technique, subtractive manufacturing requires various process steps and generates material waste. Additive manufacturing (AM) techniques instead allow optimal use of material, besides enabling rapid prototyping. AM methods are thus especially interesting for the fabrication of electronic components such as MPAs. AM methods include both 2D and 3D techniques, which can also be combined to embed components within 3D-printed enclosures, protecting them from hazards and/or developing haptic interfaces. In this work, we exploit the combination of 2D and 3D printing AM techniques to realize three MPA configurations: flat, curved (at 45∘), and embedded. First, the MPAs were designed and simulated at 2.3 GHz with a −16.25 dB S
11 value. Then, the MPA dielectric substrate was 3D-printed using polylactic acid via fused deposition modeling, while the antenna material (conductive silver ink) was deposited using three different AM methods: screen printing, water transfer, and syringe-based injection. The fabricated MPAs were fully operational between 2.2–2.4 GHz, with the flat MPA having a higher S
11 peak value compared to the curved and embedded MPAs. Development of such AM MPAs in various configurations demonstrated in this work can enable rapid development of long-range antennas for novel applications in e.g. aerospace and Internet of Things sectors.
Male Occupations and Career Mobility
Authors: Brockliss Laurence , Smith Harry 
Published: May 2024

Abstract
Chapter 2 principally explores the extent to which sons entered the same careers as their fathers. Perhaps half the cohort did not come from a professional family but were the sons of merchants, tradesmen, and artisans. Whatever their background or wealth, there is little sign that the cohort viewed non-professional careers with disdain. Only a small minority of the cohort’s sons entered exactly the same profession as their fathers and many moved into business and trade. Some members of the cohort, moreover, lacked the means to put their sons in a profession even if they had wanted to: a handful of their sons ended up as factory workers and miners. There was the same limited evidence of occupational continuity in the case of the grandsons. What is particularly striking is that if a cohort son made a career outside the professions, there was virtually no chance that one of his sons would become a professional.
Male Family Members and Intergenerational Wealth
Authors: Brockliss Laurence , Smith Harry 
Published: May 2024

Abstract
Chapter 3 is a study of the intergenerational wealth of the male members of the families under review. It maps the spectrum of wealth left by members of the first generation, then compares and contrasts this with the wealth of their fathers and male descendants. It sets out to establish how far the professions were a passport to family fame and fortune and the factors affecting long-term success or failure. The chapter reveals that there was a huge disparity in wealth between the richest and poorest males in each generation and that a considerable percentage, not just those who ended up as artisans or labourers, had fallen out of respectable society. At the same time, the chapter shows that the large majority of sons and especially grandsons were much poorer than members of the cohort from whom they were descended. This was true even of the descendants of the richest cohort members.
Moving About
Authors: Brockliss Laurence , Smith Harry 
Published: May 2024

Abstract
Chapter 4 focuses on the geographical mobility of the 750 families. It considers how far cohort members and their male and female descendants moved around in the course of their lives locally, nationally, and internationally. Its aim is to establish to what extent the set of families surveyed in this study remained based in the same area in which they were located in 1851. The chapter explores in particular the extent to which families or branches of families were either lured to London or left Britain to build a new life in the United States or the Empire. The families dispersed slowly across time, especially those that in 1851 had already been resident in the cohort town or its surrounding county for a generation or more. Although there were differences between the town cohorts, emigration to the United States and the Empire was limited, and London had little appeal. Less than 10% of grandchildren died in the metropolis.
Male Leisure
Authors: Brockliss Laurence , Smith Harry 
Published: May 2024

Abstract
Chapter 5 is devoted to examining the wider social groups to which the cohort and their male descendants belonged and explores the associational life they cultivated in their leisure hours. Initial attention is paid to church membership. Membership of the Church of England is shown to be high, confessionally-mixed marriages common, and inter-confessional hostility rare. The rest of the chapter uncovers the degree of male involvement in local political, cultural, and recreational societies, and whether the level and direction of interest changed from one generation to the next. It demonstrates that among the better-off members of the cohort, there was widespread interest in local history and the local flora and fauna, and several undertook serious research. Other members threw themselves into local politics and served on improvement commissions. However, this enthusiasm for an active life outside home and work waned dramatically among their sons and was virtually non-existent among their grandsons, who showed some interest in sport but little else.
Nigerian Youth Engagement in Violent Electoral Environments: Political Apathy or ‘Constrained Optimism’?
Authors: Davis Justine , Turnbull Megan 
Published: May 2024

Abstract
How do young citizens engage with politicians and their political environment in contexts where elections are frequently affected by violence? We explore this question through focus group discussions (FGDs) in Nigeria, a country with high rates of election violence. We argue that young voters in violent electoral environments operate with ‘constrained optimism’, where they perceive low government responsiveness but possess high levels of self-efficacy. Participants condemned violence and expressed little faith in political institutions and leaders to curtail violence, but they also felt a determination to elect a better government and a strong sense of a civic duty to vote, participate in politics, and encourage others to do so as well. Many participants also shared that they would continue to support their preferred candidate if they were accused of violence. Some participants raised concerns about the veracity of such allegations while others explained that politicians sometimes use violence for defensive purposes. Still others stated that they would continue to support candidates who expressed remorse for engaging in violence and committed to peaceful campaigning in the future. Taken together, we argue that young voters in violent contexts operate with ‘constrained optimism’ where they remain committed to democracy, but face constraints on who they support and how they participate. Our findings nuance expectations of the effects of electoral violence on political participation and better help us understand the challenges facing voters in contexts where violence is rife.
Structural insights into starch-metabolizing enzymes and their applications
Authors: Tagami Takayoshi 
Published: May 2024

ABSTRACT
Starch is a polysaccharide produced exclusively through photosynthesis in plants and algae; however, is utilized as an energy source by most organisms, from microorganisms to higher organisms. In mammals and the germinating seeds of plants, starch is metabolized by simple hydrolysis pathways. Moreover, starch metabolic pathways via unique oligosaccharides have been discovered in some bacteria. Each organism has evolved enzymes responsible for starch metabolism that are diverse in their enzymatic properties. This review, focusing on eukaryotic α-glucosidases and bacterial α-glucoside-hydrolyzing enzymes, summarizes the structural aspects of starch-metabolizing enzymes belonging to glycoside hydrolase families 15, 31, and 77 and their application for oligosaccharide production.