Trefftz Co-chain Calculus

We propose a comprehensive approach to obtain systems of equations that discretize linear stationary or time-harmonic elliptic problems in unbounded domains. This is achieved by coupling any numerical method that fits co-chain calculus with a Trefftz method. The framework of co-chain calculus accommodates both finite element exterior calculus and discrete exterior calculus. It encompasses methods based on volume meshes: its application is therefore confined to bounded domains. Conversely, Trefftz methods are based on functions that solve the homogeneous equations exactly in the unbounded complement of the meshed domain, while satisfying suitable conditions at infinity. An example of a Trefftz method is the Multiple Multipole Program (MMP), which makes use of multipoles, i.e. solutions spawned by point sources with central singularities that are placed outside the domain of approximation. In our approach the degrees of freedom describing these sources can be eliminated by computing the Schur complement of the system for the coupling, therefore leading to a boundary term for co-chain calculus that takes into account the exterior problem. As a concrete example, we specialize this general framework for the cell method, a particular variant of discrete exterior calculus, coupled with MMP to solve frequency-domain eddy-current problems. A numerical experiment shows the effectiveness of this approach

Modelling piezoelectric energy harvesters by a finite integration technique formulation for electromechanical coupled problems

A detailed analysis and optimization of piezoelectric devices, which nowadays are of widespread use in electronic applications, requires numerical analysis. Numerical models based on the Finite Element Method (FEM) have already been proposed in literature. The Finite Integration Technique (FIT) provides stable and consistent discretization schemes for coupled multiphysics problems. A FIT formulation with unstructured meshes, for 2-D/3-D coupled electromechanical static or dynamic problems, is presented. Piezoelectric bimorph cantilevers, with a realistic multilayered geometry, can be analyzed. Comparisons with FEM show the validity and the accuracy of the method

Pulmonary and chest wall function in obese adults

Obesity is frequently associated with breathing disorders. To investigate if and how the highest levels of obesity impact respiratory function, 17 subjects with obesity (median age: 49 years; BMI: 39.7 kg/m2, 8 females) and 10 normal-weighted subjects (49 years; 23.9 kg/m2, 5 females) were studied. The abdominal volume occupied 41% in the obese group, being higher (p < 0.001) than the normal-weighted group (31%), indicating accumulation of abdominal fat. Restrictive lung defect was present in 17% of subjects with obesity. At rest in the supine position, subjects with obesity breathed with higher minute ventilation (11.9 L/min) and lower ribcage contribution (5.7%) than normal weighted subjects (7.5 L/min, p = 0.001 and 31.1%, p = 0.003, respectively), thus indicating thoracic restriction. Otherwise healthy obesity might not be characterized by a systematic restrictive lung pattern. Despite this, another sign of restriction could be poor thoracic expansion at rest in the supine position, resulting in increased ventilation. Class 3 obesity made respiratory rate further increased. Opto-electronic plethysmography and its thoraco-abdominal analysis of awake breathing add viable and interesting information in subjects with obesity that were complementary to pulmonary function tests. In addition, OEP is able to localize the restrictive effect of obesity

Nonlinear Projection-Based Approach for Generating Compact Models of Nonlinear Thermal Networks

A nonlinear projection-base approach for generating compact models of nonlinear thermal networks is proposed. This approach is an extension of Galerkin's method, based on the theory of kernels. High accuracy for large temperature variations and high compactness of the generated models can be obtained

Uncertainty Quantification for SAE J2954 Compliant Static Wireless Charge Components

The present work aims at quantifying how, and how much, the uncertainties on the components and material parameters of a wireless power transfer (WPT) system for the static charge of electric vehicles affect the overall efficiency and functionality of the final produced device. With the aim of considering the perspective of a possible industrial developer, the parameters selected for the uncertainty quantification are chosen to be the capacitance values of the compensation capacitors and the electromagnetic material parameters used for the construction of the magnetic structure of a WPT system, i.e. the parameters of the elements to be purchased. The analysis is based on a standard system among the ones provided by the current SAE J2954 recommended practice

Canonical Forms of Multi-Port Dynamic Thermal Networks

In this paper it is shown that multi-port dynamic thermal networks admit four canonical representations which generalize the four canonical representations of passive lumped RC networks : Foster I and II canonical forms, Cauer I and Cauer II canonical forms. In particular the generalized Foster I canonical form is equivalent to the time-constant representation and the generalized Cauer I canonical form is a passive multi-conductor RC transmission line

Advantages and Challenges of Tailored Regimens for Drug-Resistant Tuberculosis : A {StopTB} Italia Look into the Future

The emerge of drug-resistant tuberculosis (TB) strain in recent decades is hampering the efforts of the international community to eliminate the disease worldwide. The World Health Organization (WHO) has drafted many strategies to achieve this ambitious goal. In the very beginning, the aim was to standardize inadequate regimens used in many countries and, thereafter, evolved to tackle the social determinants which hinder TB elimination. However, following the path of narrowing the clinical vision to deal with TB, there is an increased need to personalize the treatment considering both patients and pathogen unique characteristics. In our narrative review, we report the advantages and the backwards in developing a method to implement the concept of precision medicine to the treatment of TB. In this dissertation, we highlight the importance to address different aspects of the diseases encompassing the host and pathogen features, as well as the needs to further implement an adequate follow-up based on the available resources. Nevertheless, many things may hamper the vision of precision medicine in TB, such as the complexity and the costs to develop novel compounds and the costs related to global-scale implementation of patient-centered follow-up. To achieve the ambitious goal of TB elimination, a radical change in TB treatment is needed in order to give a more comprehensive approach based both on patients\u2019 peculiarities and driven by drug susceptibility tests and whole-genome sequencing

Lumped electro-thermal model of on-chip interconnects

The paper proposes a compact but accurate electro-thermal model of a long on-chip interconnect embedded in a ULSI circuit. The model is well suited to be interfaced with the commercially available tools employed in ICs design for interconnect parasitic extraction

Short bouts of anaerobic exercise increase non-esterified fatty acids release in obesity

PURPOSE: It is demonstrated that aerobic exercise plays an important role in weight loss programs for obesity by increasing 24 h metabolic rate. While aerobic exercise can result in health and fitness benefits in obese subjects, also independently of weight loss, not completely clear are the effects of bouts of hard exercise on metabolic outcomes. The aim of this study was to test the hypothesis that short-term aerobic activity with anaerobic bouts might result in a greater improvement in the management of obesity than aerobic activity alone. METHODS: We studied 16 obese subjects (eight men) during a progressive cycloergometric test up to exhaustion, before and after 4 weeks of two different training schedules (6 days/week). Insulin and glycaemia, non-esterified fatty acids (NEFA) and lactic acid were sampled. Group A (eight subjects, four men) performed an aerobic cycle workout; Group B (eight subjects, four men) performed a 25 min aerobic workout followed by 5 min of anaerobic workout. All the subjects maintained their individual eating habits. RESULTS: The post-training test showed a decrease in AUCs NEFA in Group A (p < 0.05) and an increase in Group B (p < 0.05), together with an increase in lactic acid in Group A and a decrease in Group B (p < 0.01). \u3b2-cell function (HOMA2-B) revealed a reduction only in Group A (p < 0.05). Group B achieved a greatest reduction in body fat mass than Group A (p < 0.05). CONCLUSIONS: Aerobic plus anaerobic training seem to produce a greater response in lipid metabolism and not significant modifications in glucose indexes; then, in training prescription for obesity, we might suggest at starting weight loss program aerobic with short bouts of anaerobic training to reduce fat mass and subsequently a prolonged aerobic training alone to ameliorate the metabolic profile