Elliptic regularization of some semilinear parabolic free boundary problems

We prove the existence of strong solutions to a family of some semilinear parabolic free boundary problems by means of elliptic regularization. The Existence of solutions is obtained in two steps: we first show some uniform energy estimates and then we pass to the weak limit. To carry out the latter step, we establish uniform non-degeneracy estimates for the approximating sequence as well as parabolic non-degeneracy and optimal regularity for the limit solution. To the best of our knowledge, this is the first time the elliptic regularization approach is used in the context of parabolic obstacle problems

Dialogues with digital wisdom: can LLMs help us put down the phone?

The use of Large Language Models (LLMs) to counter problematic smartphone use and support users’ digital wellbeing has recently gained research interest. Yet, such an approach is still in its infancy, particularly when compared to traditional digital self-control interventions. In this paper, we explore the possibility of using LLMs as “digital wellbeing assistants.” Specifically, we first reviewed the HCI literature and developed four user personas that exemplify widely recognized issues associated with smartphone (over)use. Then, we assessed the capabilities of four popular LLMs-powered chatbots, i.e., Bing, ChatGPT, Gemini, and Claude.AI, in understanding problematic smartphone uses and suggesting practical strategies to address them, using the developed personas as a testing ground. Despite some variations, results show that all three LLMs can offer tailored suggestions based on user characteristics, opening doors for smarter digital self-control interventions that leverage AI to support users’ self-monitoring and regulation capabilities

Modeling Excitable Cells with Memristors

This paper presents an in-depth analysis of an excitable membrane of a biological system by proposing a novel approach that the cells of excitable membrane can be modeled as the networks of memristors. We provide compelling evidence from the Chay neuron model that the state-independent mixed ion-channel behaves as a nonlinear resistor, while the state-dependent voltage-sensitive potassium ion-channel and calcium-sensitive potassium ion-channel function as generic memristors from the perspective of electrical circuit theory. The mechanism to give the rise to the periodic oscillation, aperiodic (chaotic) oscillation, spikes and bursting in an excitable cell are also analyzed via small-signal model, pole-zero diagram of admittance functions, local activity, edge of chaos and Hopf bifurcation theorem. It is also proved that the zeros of the admittance functions are equivalent to the eigenvalues of the Jacobian matrix and the presence of the positive real parts of the eigenvalues between the two bifurcations points lead to the generation of complicated electrical signals in an excitable membrane. The innovative concepts outlined in this paper pave the way for a deeper understanding of the dynamic behavior of excitable cells, offering potent tools for simulating and exploring the fundamental characteristics of biological neurons

La statica delle volte, alla prova delle bombe

Il comportamento statico delle volte a prova di bomba costituisce un tema lungamente dibattuto che, a seguito della rivoluzione balistica di metà Settecento, divenne oggetto di una intensa attività teorica e sperimentale. A partire da un nostro precedente studio sulla teoria sviluppata a partire dal 1756 dal piemontese Papacino D’Antoni, basata su un’estensione del meccanismo di scorrimento di De La Hire, ci proponiamo in questo contributo di analizzare altri lavori di epoca napoleonica e di ambito francese nei quali alcune delle questioni lasciate aperte da Papacino sembrano trovare una trattazione fisicamente convincente

Transient Thermal Analysis of Space Rectangular Thin-Walled Structures by Carrera Unified Formulation

The accurate prediction of transient thermal fields of space structures is of paramount significance for the analysis of geometrical stability and thermal management systems. This paper proposes a novel method to solve the transient thermal field of the thin-walled cross section of beams in outer space. High-order beam elements are derived by means of the Carrera unified formulation (CUF), where the longitudinal direction of the beam is discretized by one-dimensional two-node and four-node elements, whereas arbitrary high-order expansion functions are used for the description of the temperature expansion within the cross section. The governing differential equations of the transient temperature field are derived according to the transient thermal conduction theory and the weighted residual method. The solution of the initial value problem for ordinary differential equations is obtained through the application of the Adams-Bashforth method, leading to the determination of the transient thermal field. In order to demonstrate the accuracy of the temperature results, a convergence analysis is conducted. Finally, temperature distributions within the cross section and along the longitudinal direction of the model are discussed to show the effects of several factors, including material properties, angle of solar radiation, and shadows induced by the shelter of other components

Magnetic Hyperthermia to Promote Acrylamide Radical Polymerizations

Radical polymerization is widely employed for the preparation of advanced materials with controlled properties and responsiveness. Depending on the radical initiator, different stimuli can trigger the beginning of the reaction. This work presents an innovative approach that exploits the heat released by magnetic nanoparticles when they are excited by an alternating current (AC) magnetic field to induce radical polymerizations. In particular, the use of cobalt ferrite (CoFe2O4) nanoparticles is explored for the preparation of polyacrylamide hydrogels, chosen as a model material to demonstrate the strategy. Magnetic and mechanical characterizations reveal that the materials possess properties similar to those of samples prepared by classical thermal polymerization. Indeed, magnetic hyperthermia is a versatile tool for remote temperature control in a localized space that can have different applications. An example is represented by its use for a selective volume polymerization in a thermosensitive environment, overcoming classical problems of both bulk thermal polymerization (e.g., not applicable in delicate environments) and photopolymerization (e.g., poor light penetration). The obtained results pave the way also for production of non-magnetic materials, in which magnetic nanoparticles are first concentrated in a small solution volume (by a permanent magnet) and then exploited to activate the polymerization of the whole material (by an AC magnetic field)

A Study on the Cradle-to-Gate Environmental Impacts of Automotive Lithium-ion Batteries

Several factors are influencing the spread of Electric Vehicles (EVs) in the automotive market. However, while battery-electric vehicles emit no tailpipe emissions, the manufacturing phase, particularly the manufacturing of the battery packs, can have significant environmental impacts. In addition, as the EV market expands, there will be a significant increase in demand for critical materials used in lithium-ion batteries, such as lithium, cobalt, and nickel. These materials are essential for producing high-performance batteries, and their global demand is expected to rise rapidly to meet the demands of the expanding market. This paper investigates the main challenges that need to be tackled to reach a sustainable path in the battery industry. A cradle-to-gate boundary is set to focus on raw material extraction, production of precursors, cell and module production, and battery pack assembly. In addition, because 7.8 million tons of EV batteries per year are expected to reach the end-of-life phase by 2040, a brief overview of the recycling issue is provided to investigate the potential usage of recycled material in the early stages of battery production