IRIS Università degli Studi dell'Aquila
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Stiffness Prediction of Wooden Dowel Connections with Beam-on-Foundation Models
No full textThe renewed interest in pure wood connections has brought wooden dowels back into focus. They exhibit satisfactory mechanical properties in terms of strength and ductility. However, while significant research has been dedicated to capacity models, stiffness models have received less attention. Existing models are often overly simplified and fail to predict the stiffness of such connections accurately. To address this gap, this study develops several beam-on-foundation models with linear embedment to simulate the stiffness of pure wood shear connections. The tested connections are assembled using glulam and three types of wooden dowels: laminated densified wood, birch, and beech. This work aims to assess the influence of modeling assumptions on prediction accuracy, particularly focusing on the effects of dowel shear deformability and the choice of the subgrade stiffness. Specifically, the authors discuss whether the subgrade stiffness should be derived from steel-wood embedment tests, as recommended by existing standards, or from wood-wood embedment tests. This study highlights the limitations of current stiffness prediction models for wooden dowel connections and underscores the need for semiempirical ones tailored to wooden dowel connections
A BI-DIMENSIONAL MODEL BRIDGING MICRODAMAGE EVOLUTION AND BONE REMODELING: A COMPUTATIONAL STUDY ON A HUMAN FEMUR
No full textBone remodeling is a complex biological process that maintains skeletal integrity through adaptation to mechanical and biochemical stimuli. This study introduces a novel two-dimensional model designed to analyze the interaction between bone remodeling and damage evolution within a realistic femur geometry. The proposed methodology considers spatial variations in strain distribution and damage accumulation. The model augments a diffusion-based remodeling framework by incorporating damage evolution laws to predict microdamage progression, healing mechanisms, and biomechanical adaptation. Numerical simulations explore the impact of key parameters, including the diffusion of remodeling stimulus, damage accumulation, and healing rates. The results indicate that optimal remodeling occurs when stimulus diffusion is neither excessively rapid nor overly localized, identifying the femoral neck as a high-risk area for structural degradation. The findings provide clinically relevant information on fracture risk assessment, osteoporosis progression, and implant design optimization. Future investigations will aim to extend the model to three dimensions and include patient-specific anatomical characteristics to improve predictive capabilities
Fibre-enriched high-carbohydrate (FEHC) diet modulates inflammation without af-fecting bone health in older women with obesity: A randomised clinical trial
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Resistorless Current-Mode Schmitt Trigger for Single-Event Detection in Photomultipliers Front-Ends
No full textThis work proposes an integrated current-mode non-inverting Schmitt Trigger in a 150nm CMOS technology, without any feedback passive element, for photomultipliers single-event detection. The proposed device is triggered by a current input signal and provides an output voltage that is suitable for interfacing with digital systems. The small currents associated with a reduced number of photoelectrons require a high transimpedance gain and a narrow hysteresis width, making conventional approaches impractical. The proposed device shows a current threshold value to trigger the system, offering a high detection capability also with small currents. In addition, it makes the trigger hysteresis width less sensitive to supply variations. The proposed circuit has great design flexibility, also allowing user to tune the threshold currents using bias voltage reference. The proposed device properly operates under a power supply voltage 1.8 V to 3.3 V. Static power consumption is 10 μW, with a propagation delay of 25 ns and a total detection delay of 34 ns, driving a 3 pF load capacitance
Investigating the Role of LLMs Hyperparameter Tuning and Prompt Engineering to Support Domain Modeling
No full textThe introduction of large language models (LLMs) has enhanced automation in software engineering tasks, including in Model Driven Engineering (MDE). However, using general-purpose LLMs for domain modeling has its limitations. One approach is to adopt fine-tuned models, but this requires significant computational resources and can lead to issues like catastrophic forgetting. This paper explores how hyperparameter tuning and prompt engineering can improve the accuracy of the Llama 3.1 model for generating domain models from textual descriptions. We use search-based methods to tune hyperparameters for a specific medical data model, resulting in a notable quality improvement over the baseline LLM. We then test the optimized hyperparameters across ten diverse application domains. While the solutions were not universally applicable, we demonstrate that combining hyperparameter tuning with prompt engineering can enhance results across nearly all examined domain models
Axially-Laminated Synchronous Reluctance Machine Rotor Materials and Evaluation of Manufacturing Methods: Mechanical and Electromagnetic Validation
No full textHigh-speed (HS) electric machines increase power density by elevating rotor speed, enabling direct connection to an application such as compressors or turbine impellers. These features benefit, for example, industrial or aviation applications. The HS operation requires a rugged rotor to handle the high centrifugal loads, while the electromagnetic performance should, at the same time, be acceptable. This research investigates the mechanical and electrical performance of three axially laminated anisotropic synchronous reluctance rotor configurations for a 12 kW 24 000 rpm motor. The axially laminated rotors have magnetic and non-magnetic layers joined using hot isostatic pressing or vacuum brazing. The results show that all the studied rotor constructions achieve sufficiently homogeneous structures, and good electromagnetic performance, and are feasible for HS operation
Long‐Term Performance of Bi‐Layered Single Crowns Supported by Zirconia Implants: 7.5‐Year Results of a Two‐Center Prospective Cohort Study
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Objective: To evaluate the survival and success rates of veneered zirconia-based single crowns (SCs) supported by zirconia implants in posterior regions, along with patient-reported outcomes, over 7.5 years.
Materials and methods: Forty-five patients received zirconia implant-supported posterior SCs (n = 45) composed of zirconia frameworks layered with a leucite-reinforced feldspathic ceramic. At 7.5 years, clinical parameters and technical complications were assessed. Technical success was determined according to modified United States Public Health Service (USPHS) criteria. Patient-reported outcome measures (PROs) were evaluated using visual analog scales (VAS). Wilcoxon matched-pairs signed-rank test, mixed-effects ordered logistic regression, and linear mixed models analyzed time-dependent effects.
Results: Thirty SCs (n = 30) could be evaluated at the 7.5-year follow-up (mean: 92.1 ± 3.4 months). Kaplan-Meier survival for SCs was 97.5% [95% CI: 83.6%-99.6%]. Success dropped to 79.4% [63.0%-89.2%] due to reconstructions with major chipping (n = 3), occlusal roughness (n = 7), marginal crevice (n = 1), and over-contouring (n = 2). PROs showed significant improvements from pre-treatment to delivery (VAS scores: 93%-97%) and remained stable throughout the follow-up period.
Conclusion: Veneered zirconia-based SCs supported by zirconia implants in posterior sites demonstrated high survival rates and consistently met patients' functional and esthetic expectations. Despite these favorable outcomes, the considerable incidence of technical complications warrants further investigation through long-term clinical studies.
Clinical significance: While veneered zirconia crowns offer favorable esthetics, their susceptibility to chipping in posterior regions suggests that monolithic alternatives may be preferable. Further research is needed to optimize material selection and minimize technical complications
Fundamental Superalgebras with Superinvolution: Exploiting Minimal Varieties
Get PDFThis paper extends the concept of fundamental superalgebra, crucial in Kemer’s resolution of the Specht problem, to the framework of superalgebras equipped with a superinvolution. We aim to characterize the class of these special algebras and provide concrete examples. Some of them are developed by exploring connections with varieties of superalgebras with superinvolution which are minimal with respect to their corresponding exponent
Integrated and Sustainable Urban Regeneration for Resilient University: A Case Study
No full textIntegrated urban regeneration can be considered
a paradigm of modern society, which systematizes the needs of
resilience of the territory with a policy aimed at improving its
competitiveness, through an approach characterized by social,
economic and environmental sustainability. The need for
regeneration of the built environment, in particular that related
to university functions, requires a specific methodological
approach, which look at the complexity of the various aspects.
The proposed design methodology is a response to the lack of
operational tools in place, for the purpose of effective and
efficient redevelopment. The case study presented in the
research is related to the University Campus of Coppito, one of
the three university centers of the city of L'Aquila. The study
proposes a methodology to reconfigure the complex,
refunctionalizing its spaces and connections, creating new
spaces for social aggregation and study, technologically
advanced. The innovative approach intends to pursue an
integrated urban regeneration that aims to open the university
center to the city and the community