bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Sustained High-Temperature on the Reliability of Lead-Free Solder Joint Assemblies Under Vibration
Authors: Lall Pradeep , Mehta Vishal , Suhling Jeff , Locker David 
Published: November 2023

Abstract
Electronic parts in the automotive, downhole drilling of oil & gas, and aerospace sectors are frequently subjected to severe high strain loads. Those extreme loads may be occurring as a result of shocks, vibrations, and drop-impact circumstances. In addition, these parts are frequently exposed to severe low and high temperatures ranging from −65°C to 200°C. In such critical environment, these electronic equipment can be exposed to strain rates ranging from 1 to 100 per second. SAC solder alloys are the most often used alloys to replace tin-lead solders in electronic assembly applications. Tin, silver, and copper are the essential elements in these lead-free alloys. SAC solder alloys have proven to be successful in surface mount, wave soldering, and hand soldering applications. The primary advantage of RoHS certified lead-free solder is that it is safer than lead solder, which is a severe neurotoxic. Numerous doped solder alloys, such as SAC-Q, SAC-R, Innolot, M758 etc. have recently been introduced in electronic components. Mechanical characteristics and statistics for lead-free solder alloys are critical for enhancing electronic package durability at high temperatures and strain rates. Combined effects of higher temperatures and vibrations in electronic components might result in rapid failure. The majority of previous solder joint research has been on either vibrational stresses or thermal cycling for conventional solders like SAC105, and SAC305. SAC alloy failure mechanisms were investigated in this article at higher surrounding test temperatures up to 155°C, as well as at vibration loads of 5g and 10g levels. Harmonic vibrations at the first natural frequency was measured for the test boards with CABGA daisy-chained package at various test temperatures and vibration g-levels. Results on assembly response and resistance were collected utilizing high-speed data acquisition and highspeed imaging. A high-speed camera system was employed to catch the vibration event during testing. Stresses in solder interconnects were calculated using Finite Element Analysis simulation. The impact of g-levels, and operating temperatures on the hysteresis loop and plastic work density has been investigated. The failure mode analysis for the test board has been performed. Anand viscoplasticity material data for the solder alloys which were previously published by authors were used to capture the high-strain rate behavior and temperature dependent aging behavior of the solder junctions for FE analysis.
Variable Area Jet Impingement for High Voltage Power Electronics
Authors: Whitt Reece , Huitink David 
Published: November 2023

Abstract
Convective heat transfer by jet impingement cooling offers a suitable solution for these high heat flux applications. Compared to techniques that rely on bulk conduction in series with convection, direct liquid impingement reduces the thermal resistance between power device hot spots and the coolant. Although capable of highly efficient cooling, static impingement devices must be designed for the worst-case cooling requirements for a transient power profile, possibly resulting in a wasted hydraulic performance. Aircraft, highway vehicles, and heavy machinery fall into this category where a substantial factor of safety is required. This work proposes a method for improving power electronics reliability by limiting temperature fluctuations at reduced coolant pressure requirements during transient power cycling using a variable area jet. Single phase jet impingement cooling is implemented in an active control scheme using a variable diameter iris mechanism as the primary nozzle architecture. In addition to pressure drop and temperature control, the active nozzle structure introduces the ability to create pulsating jet flows to further enhance the heat transfer compared to fixed-geometry nozzles. The key underlying fluid mechanics characteristic of pulsating flows is the effect of disrupting the thermal boundary layer on the electrical device surface. By introducing a variable diameter jet, eddy formation can be fine-tuned for optimal boundary layer disruption. Using the definition of the Strouhal number, vortex shedding created by the non-steady jet flows is directly correlated with the resulting Nusselt number as a function of the iris kinematics. An experimental apparatus for jet impingement thermal-fluid testing is used to evaluate the Nusselt number versus Strouhal number for a parametric study of variable diameter iris configurations. The apparatus utilizes a voice coil actuator to achieve sine and square wave forms, varying amplitude of actuation, and varying mean of actuation. Finally, power cycling with a single emulated hot spot is performed to estimate the reliability increase as a result of maintaining constant junction temperatures with the active jet impingement scheme.
Parametric Studies of Flexible Sandwich Panels As a Compliant Fairing for Folding Wingtip Joints
Authors: Mahid Nuhaadh Mohamed , Schenk Mark , Titurus Branislav , Woods Benjamin King Sutton 
Published: November 2023

Abstract
This paper presents a parametric study into the design space of morphing fairings for the Semi-Aeroelastic Hinged (SAH) folding wing concept. The fairing will cover the angled hinge region of the wingtip with a smooth and continuous skin surface to reduce drag. It is made from flexible sandwich panels employing the Geometrically Anisotropic ThermOplastic Rubber (GATOR) morphing skin concept, with a chevron-based cellular core covered in elastomeric facesheets. A parametrically defined finite element analysis framework is established and used to explore the mechanical response of a three-dimensional wing fairing. The two design objectives are minimising torsional stiffness and out-of-plane deformation during the rotation of the underlying wingtip joint. A parameter sweep is used to establish correlations between the design variables and the competing objectives. Notable correlations were identified for the chevron wall angle, core thickness, facesheet thickness, fairing span, pre-strain and flare angle. Pre-straining the facesheets is found to delay the onset of large changes in surface curvature and the subsequent softening of stiffness. However, it also leads to higher levels of torque at large rotation angles. Overall, this study helps to elucidate the design trends for compliant fairings while also reducing the design space in preparation for further studies.
Evaluation of Interface Strength and Failure Between Nickel-Titanium Shape-Memory-Alloy Wire and Bismuth-Tin Matrix for the Design of Self-Healing Composites
Authors: Haider Muhammad Istiaque , Church Benjamin , Salowitz Nathan 
Published: November 2023

Abstract
Self-healing materials can lead to a paradigm shift in engineering design by enabling lighter weight & more efficient structures, reducing maintenance requirements, and changing the definition of failure. Among self-healing materials, metalmetal composites have the potential for some of the most advanced capabilities, being entirely structural and healing without consumable components.
Despite potential advantages, metal-metal self-healing composites are challenging to synthesize, as a result most research has focused on polymeric or ceramic self-healing materials. NiTi fiber reinforced off-eutectic BiSn matrix composite structures have demonstrated some of the most advanced self-healing abilities. After one of these non-autonomic self-healing structures incurs damage, the self-healing capability can be activated through the application of heat. Increase in temperature activates the shape memory effect in the NiTi, restoring bulk geometry and closing fractures. Continued heating results in melting of eutectic portions of the BiSn matrix which solders the matrix back together. Combined these abilities result in restoration of macro-scale geometry and near 100% restoration of strength without expending any internal consumable reagents. Therefore, the process can be repeated indefinitely.
One of the primary challenges in designing this composite structure is understanding the interface between the NiTi and BiSn. The strength and mechanisms of failure around this interface are critical to designing the composite (i.e. sizing the fibers) and understanding the resulting effects on strength and self-healing ability. A primary obstacle is that NiTi forms an inert titanium oxide (TiO2) surface layer almost instantly upon exposure to air. The TiO2 layer severely inhibits bonding between NiTi and BiSn (or most any other materials).
This paper presents an experimental and theoretical investigation into the properties of the interface between NiTi and BiSn in both a control state with the native TiO2 present and an experimental state where chemical etching processes were performed in an inert environment to remove the TiO2 and prevent is re-formation. Experimental specimens were synthesized, mechanically tested, and microscopically inspected. Modeling was performed to understand internal states of the structure and theory was developed consistent with and explaining observed results.
The results of this work quantified the improvement in interface strength between NiTi and BiSn achieved through the etching process. Quantification of this overall strength provides vital information for composite design optimization and sizing of wires. However, these analyses will differ from inactive composites to account for internal loads generated by the healing process and potential development of TiO2 upon incurring damage.
Scanning on a Thin Slice: An Examination of a Magnetostrictive Sputtered 3D Printed Carbon Fiber Composite
Authors: Nelon Christopher , Williams Brandon , Myers Oliver , Hall Asha , Seifu Dereje 
Published: November 2023

Abstract
Components designed for nondestructive evaluation or structural health monitoring applications often leverage smart materials, either mounted on the surface or embedded within, as a sensing element. The principle of magnetostriction represents a viable relationship to exploit in health assessment, especially with carbon fiber composites. A commercial carbon fiber filament for additive manufacturing, Onyx, consists of chopped fibers suspended in a polymeric host to enable heating and deposition on a build plate. Physical vapor deposition (PVD) sputtering provides an inert environment for safely depositing thin films of Terfenol-D, a highly pyrophoric magnetostrictive material when utilized in micro-sized particulate form, onto the surface of substrates. The sputtering process deposited magnetostrictive thin films onto a 6-millimeter diameter indentation surface in the gage area of 3D printed Onyx specimens. Heat treatment pre- and post-sputtering altered the crystal structure of the Onyx substrate, evident by the results of quasistatic uniaxial tensile experiments. Examination of the stress and strain data from the tensile tests found the elastic modulus and yield stress of the heat-treated, sputtered specimens to increase by nearly 77% and 62%, respectively, compared to the baseline specimens. A magnetometer aligned with the sputtered Terfenol-D regions provided magnetic flux density readings throughout the quasistatic tests. The alignment of the magnetometer probe relative to the sputtered surface influenced the magnitude of the magnetic flux density reading. Elongation of the Onyx material displaced the sputtered region from the initial alignment with the probe during testing resulting in variations in the magnitude of the magnetic flux density measurements. The ability to capture a magnetic response from a surface-deposited thin film of the highly magnetostrictive material Terfenol-D, with an estimated volume of 0.035 cubic millimeters, makes sputtering an excellent technique for developing a small displacement sensing element to detect damage in CFRP laminates and 3D printed composite components.
On the Resonance/Bandwidth-Coupling Relationship of Electromagnetic Vibration Energy Harvester With a Non-Varying Magnetic Flux Density
Authors: Toluwaloju Tunde Isaiah , Thein ChungKet , Halim Dunant 
Published: November 2023

Abstract
An investigation on how the degree of coupling determined by the coil size and the magnet spacing affects the bandwidth and or resonance of an electromagnetic vibration energy harvester was presented in this work. The vibration energy harvesting model was realized as a magnet mounted on a linear spring, the response of the magnet was however constrained using a mechanical slider/guiderail. The guiderail introduces another Coulomb damping different from the mechanical and electromagnetic damping into the model. The transduction coil is fixed with the base such that during excitation, the response of the magnet over the guiderail induces field in the coil, thereby generating electrical energy. Six different coil geometries of widths 4.00 mm, 6.00 mm, 8.00 mm, 10.00 mm and 12.00 mm were tested within two different magnet spacing configurations realized as a fixed spacing (14.00 mm) and variable spacing. The variable space corresponds to the coil width added to 2.00 mm clearance spacing. To establish a baseline for effective performance comparison between different models analyzed, the respective mechanical property such as the mechanical damping coefficients, mechanical stiffness and the model inertia masses are fixed The magnetic flux density on each designs were simulated on a Finite Element Magnetic Software (FEMM) software while the actual harvested voltage, power, optimum load capacity, resonance/bandwidth were queried in the MATLAB using relevant analytical governing equations. According to the Ohm’s law, the harvested voltage-resistance relationship indicates that using smaller coil in larger magnet spacing is beneficial for realizing vibration harvester model suitable for powering high current, low impedance sensor since such configurations is characterized by low optimum impedance. However, using coil geometries with commensurate spacing will realize capacity for operating low current, high impedance sensor because the optimum impedances are quite higher. Also, comparing similar geometry shows that the power density improved by 30.74 %, 18.06 %, 14.75 %, 7.29 % and 0 %, on coil geometries 4.00 mm, 6.00 mm, 8.00 mm, 10.00 mm and 12.00 mm respectively.
Early environmental risk factors and coeliac disease in adolescents: a population-based cohort study in Denmark
Authors: Crawley Cæcilie , Sander Stine Dydensborg , Nohr Ellen Aagaard , Nybo Andersen Anne-Marie , Husby Steffen 
Published: November 2023

ObjectivesOur aim was to investigate the association between early environmental factors and the development of coeliac disease (CeD) in adolescents, recruited from a cohort nested in the Danish National Birth Cohort (DNBC).DesignThe study was designed as a prospective cohort study, nested in DNBCParticipantsThe Glutenfunen cohort comprises 1266 participants, nested in DNBC. All participants were screened for CeD, and in total, 28 cases of biopsy proven CeD were identified. Data about breastfeeding, timing of introduction to solid food in infancy, use of antibiotics, infections and symptoms were parentally reported prospectively at 6 months and 18 months, respectively. We estimated ORs and 95% CIs of CeD in adolescents using logistic regression analysis.ResultsViral croup reported at 18 months of age was associated with CeD in adolescents with an OR of 3.2 (95% CI: 1.2 to 8.7). Furthermore, otitis media also reported at 18 months of age was linked with CeD with an OR of 3.2 (95% CI: 1.5 to 7.3). We were not able to find any statistical associations between CeD and breastfeeding, frequency of infections, parentally reported use of antibiotic and timing of solid foods.ConclusionIn this study, we present an overview of the relationship between early environmental factors and occurrence of CeD in adolescents. Our findings, despite limitations due to a limited number of cases of CeD, suggest a role of viral infections in the pathogenesis of CeD
Integrating participants as partners in research governance and operations: an approach from theAll of UsResearch Program Engagement Core
Authors: Hammack-Aviran Catherine , Fair Alecia Malin , Aldrich Melinda , Richmond Jennifer , Carpenter Selena McCoy , Watson Karriem S , Cohn Elizabeth G , Wilkins Consuelo Hopkins 
Published: November 2023

ObjectivesDuring the last two decades, researchers and funders increasingly recognised the value of engaging patients and communities in research. Despite progress, community engagement remains challenging. There are few examples of successful participant engagement in governance of large-scale research programmes. Here we describe efforts to engage participants as partners in new governance roles in theAll of UsResearch Program, a precision medicine research initiative which intends to enrol at least one million participants. Using intentional, participant-centric engagement strategies, theAll of UsEngagement Core recruited and integrated a diverse group of participants into governance roles including Steering and Executive Committees. Evaluation measures included a survey to assess Consortium Members’ readiness for participant engagement.ResultsOver a 3-year period, all items on the survey increased (higher readiness). Of the 291 respondents to the 2021 survey, respondents most frequently agreed that participant perspectives are essential (100%), participants understand enough to contribute meaningfully (94%) and participants should be involved in setting goals (96%). Respondents least frequently agreed that participants should have an equal voice in Working Groups (75%), Steering Committee (69%) and Executive Committee (63%).ConclusionIn conclusion, participants can be effectively integrated into large-scale research governance, which is associated with increased researcher readiness for engagement.
Characterising the interventions designed to affect the reporting of musculoskeletal imaging: a scoping review protocol using the COM-B model
Authors: Kirby Edward , MacMillan Andrew , Liew Bernard X W , Brinkley Andrew , Bateman Andrew 
Published: November 2023

IntroductionAttributing musculoskeletal (MSK) pain to normal and commonly occurring imaging findings, such as tendon, cartilage and spinal disc degeneration, has been shown to increase people’s fear of movement, reduce their optimism about recovery and increase healthcare costs. Interventions seeking to reduce the negative effects of MSK imaging reporting have had little effect. To understand the ineffectiveness of these interventions, this study seeks to scope their behavioural targets, intended mechanisms of action and theoretical underpinnings. This information alongside known barriers to helpful reporting can enable researchers to refine or create new more targeted interventions.Methods and analysisThe scoping review will be conducted in accordance with the JBI methodology for scoping reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Search terms will be devised by the research team. Searches of MEDLINE, EMBASE, CINAHL, AMED and PsycINFO from inception to current day will be performed. The review will include studies, which have developed or evaluated interventions targeting the reporting of MSK imaging. Studies targeting the diagnosis of serious causes of MSK pain will be excluded. Two independent authors will extract study participant data using predefined extraction templates and intervention details using the Template for Intervention Description and Replication checklist. Interventions will be coded and mapped to the technique, mechanism of action and behavioural target according to the Capability, Opportunity, Motivation-Behaviour (COM-B) model categories. Any explicit models or theories used to inform the selection of interventions will be extracted and coded. The study characteristics, behaviour change techniques identified, behavioural targets according to the COM-B and context specific theories within the studies will be presented in narrative and table form.Ethics and disseminationThe information from this review will be used to inform an intervention design process seeking to improve the communication of imaging results. The results will also be disseminated through a peer-reviewed publication, conference presentations and stakeholder events.
Key CT markers for predicting haemorrhagic transformation after ischaemic stroke: a prospective cohort study in China
Authors: Wei Chenchen , Wu Qian , Liu Junfeng , Wang Yanan , Liu Ming 
Published: November 2023

ObjectivesLimited studies have systematically addressed the CT markers of predicting haemorrhagic transformation (HT). We aimed to (1) investigate the predictive ability of the imaging factors on multimodal CT for HT and (2) identify the key CT markers that can accurately predict HT while maintaining easy and rapid assessment in the early stage of stroke.Design and settingThis was a prospective cohort study conducted in a tertiary hospital in Southwest China.ParticipantsPatients with ischaemic stroke admitted within 24 hours after onset were included.Outcome measuresThe primary outcome was measured as the overall HT. The secondary outcomes were the presence of parenchymal haematoma, symptomatic HT and spontaneous HT.ResultsA total of 763 patients were included. The early hypodensity >1/3 of the middle cerebral artery (MCA) territory, Alberta Stroke Programme Early CT Score≤7, midline shift, hyperdense middle cerebral artery sign (HMCAS), poor collateral circulation, infarct core and penumbra was independently associated with the increased risk of HT (all p < 0.05). The sensitivity of midline shift for predicting HT was only 3.5%, whereas its specificity was 99.8%. The combination of the early hypodensity >1/3 of the MCA territory, midline shift and HMCAS showed a good predictive performance for HT (area under the curve 0.80, 95% CI 0.75 to 0.84).ConclusionsSeven imaging factors on multimodal CT were independently associated with HT. The high specificity of midline shift suggests the need to consider it as an imaging indicator when assessing the risk of HT. The early hypodensity >1/3 of the MCA territory, midline shift and HMCAS was identified as the key CT markers for the early prediction of HT. The coexistence of the three key factors might be a valuable index for identifying individuals at high bleeding risk and guiding further treatments.