A two-step hybrid approach for modeling the nonlinear dynamic response of piezoelectric energy harvesters

An effective hybrid computational framework is described here in order to assess the nonlinear dynamic response of piezoelectric energy harvesting devices. The proposed strategy basically consists of two steps. First, fully coupled multiphysics finite element (FE) analyses are performed to evaluate the nonlinear static response of the device. An enhanced reduced-order model is then derived, where the global dynamic response is formulated in the state-space using lumped coefficients enriched with the information derived from the FE simulations. The electromechanical response of piezoelectric beams under forced vibrations is studied by means of the proposed approach, which is also validated by comparing numerical predictions with some experimental results. Such numerical and experimental investigations have been carried out with the main aim of studying the influence of material and geometrical parameters on the global nonlinear response. The advantage of the presented approach is that the overall computational and experimental efforts are significantly reduced while preserving a satisfactory accuracy in the assessment of the global behavior

Agritourism and territorial framework in the northern Salento (Apulia region, Italy)

The Territory Landscape Plan of the Apulia Region (PPTR)focuses on rural areas and agricultural sector, putting them in a holistic local and socio-economic context. This strategy isimplemented through the town-country pact, one of the five local projects proposed by the PPTR. The aim of the research is the study of the context and specificity of agritourism in Ostuni and Fasanocoastal areas (northern Salento), in which natural beauties, such as rural and coastal landscapes, coexist, characterized by ancient olive groves, historical rural houses and charming towns. In particular, the study analyses this rural context by means of the relationship between agritourism and territorial framework in order to check the sustainability of the development processes and their consistency with the programmatic guidelines of the PPTR. Qualitative approacheshas been used, such as semi-structured interviews and photographic material

Modeling and simulation of cantilever beam for wind energy harvesting

Energy Harvesting (EH) is the science that studies the conversion of energy dispersed in environment into a different and more useful form of energy, mainly the electrical one. In recent years, several energy-harvesting devices using piezoelectric materials have been developed to transform environmental vibrations into electrical energy. Since most piezoelectric energy harvesters are in form of cantilevered beams, the aim of this paper is to model and simulate a cantilever beam as energy harvester from wind-induced vibrations. The behavior of a cantilever beam with a fixed configuration (dimensions, materials, boundaries and shape) subjected to wind pressure was observed in an experimental apparatus and the reaction of the same device was described with a mathematical model based on piezoelectric constitutive equations and mechanical equilibrium equations. The device was simulated with the Comsol Multiphysics software that implements the equations of the mathematical model by the Finite Element Method (FEM). The experimental results were used to validate the simulation environment and their comparison with calculated results allows an appropriate choice of the most suitable piezoelectric material, among natural crystals, piezo ceramics, piezo polymers and piezocomposites, for this type of cantilever

H∞ & H2 almost state synchronization with full-state coupling for homogeneous multi-agent systems

This paper studies the H∞ and H2 almost state synchronization problem for homogeneous multi-agent systems with general linear agents affected by external disturbances and a directed communication topology. Agents are connected via diffusive full-state coupling, i.e. agents are coupled through states. A necessary and sufficient condition is developed for the solvability of the H∞ and H2 almost state synchronization problem. Moreover, a family of static protocols are developed such that the impact of disturbances on the network disagreement dynamics, expressed in terms of the H∞ and H2 norm of the corresponding closed-loop transfer function, is reduced to any arbitrarily small value. The protocol design is based on two methods: algebraic Riccati equation (ARE) or asymptotic time-scale eigenstructure assignment (ATEA)

Agro-biodiversity of Mediterranean crops: farmers' preferences in support of a conservation programme for olive landraces

The study focused on the willingness to participate in a conservation programme for olive landraces by farmers in Apulia, Italy. The choice experiment approach through a latent class model was carried out in order to investigate different characteristics of farmers which could increase the effectiveness and efficiency of conservation strategies by policy makers. The analysis identified three groups of respondents, each of which with very different characteristics: capitalist farms with high profit level managed by farmers unwilling to take part in a conservation programme; small and fragmented family farms managed by older farmers fully in favour of the programme; young farmers with low capital input, but willing to engage with a minimum participation in the programme. Policy implications suggest the need to develop markets able to appreciate the characteristics of the local olive oils, to involve farmers in marketing training programmes for a better placing of local products in the market, to support the young farmers and family farming, to set suitable policies which are able to trigger a more incisive involvement of women in conservation programmes. Such a holistic approach could generate welfare for all agents of the supply chain, in terms of profit, environment, food security and nutritional aspects

Reading in the Secondary School

High School Teachers and Research in Reading

Agro-biodiversity: an economic evaluation of benefits provided to regional community by the Apulian olive landraces

The most important anthropogenic cause of the loss of agricultural biodiversity is the rapid change in land use and the subsequent transformation of habitats, a process stemming from the economic decisions of sector agents, with significant implications for biodiversity conservation strategies in agro-ecosystems. The paper focuses on the olive sector of Apulia, Italy, one of the most important in the regional agriculture in terms of added value. In particular, it concerns the conservation of the local olive landraces based on the socioeconomic characteristics of regional citizens. Recognition of the social, economic and structural heterogeneity in community is important for estimating accurately predicting benefits and costs of agro-biodiversity management in the Mediterranean area. The paper allows studying these aspects by measuring, through a random parameter logit model, the monetary willingness of citizens of Apulia to participate in an on-farm agro-biodiversity conservation programme and by exploring how some programme attributes influence their willingness. This information can then be gathered in order to verify the suitability of the conservation strategy in force and to provide tailored references for future programmes

Achieving robust average consensus over lossy wireless networks

International audienceAverage consensus over unreliable wireless networks can be impaired by losses. In this paper we study a novel method to compensate for the lost information, when packet collisions cause transmitter-based random failures. This compensation makes the network converge to the average of the initial states of the network, by modifying the weights of the links to accommodate for the topology changes due to packet losses. Additionally, a gain is used to increase the convergence speed, and an analysis of the stability of the network is performed, leading to a criterion to choose such gain to guarantee network stability. For the implementation of the compensation method, we propose a new distributed algorithm, which uses both synchronous and asynchronous mechanisms to achieve consensus and to deal with uncertainty in packet delivery. The theoretical results are then confirmed by simulations

Using a linear gain to accelerate average consensus over unreliable networks

International audience— Packet loss is a serious issue in wireless consensus networks, as even few failures might prevent a network to converge to the correct value. However, it is possible to compensate for the errors caused by packet collisions, by modifying the updating weights. Such a modification compensates for the loss of information in an unreliable network, but results in a reduced convergence speed. In this paper, we propose a faster method – based on a suitable gain in the consensus dynamics – to solve the unreliable average consensus problem. We find a sufficient condition for the gain to preserve stability of the network. Simulations are used to discuss the choice of the gain, and to compare our method with the literature