Showing papers by "Elie Lefeuvre published in 2015"
TL;DR: In this article, the performance of a galloping-based piezoelectric energy harvester (GPEH) is modeled in a circuit simulator for system-level simulation and evaluation.
Abstract: Small-scale wind energy can be harvested for wireless sensing applications by exploiting the galloping phenomenon of a bluff body attached to a piezoelectric cantilever. Certain predictive model is required to understand the behavior of such a galloping-based piezoelectric energy harvester (GPEH). Conventional analytical and numerical models have simplified the interface circuit as a pure resistor. In practice, the energy generated by the harvester should be rectified before delivery to a real application. In such a case, the formulation of analytical or numerical model becomes cumbersome considering the complex coupling between the structure, fluid, piezoelectric transducer, and practical interface circuit. This paper proposes an equivalent circuit representation approach to predict the performance of GPEHs, capable of incorporating various interface circuits. The mechanical parameters and piezoelectric coupling in the system are represented by standard electronic components and the aerodynamic force by a user-defined component (nonstandard). The entire system is modeled in a circuit simulator for system-level simulation and evaluation. The proposed approach is verified by theoretical solution and experiment. Subsequent parametric study is performed to investigate the influence of standard ac and dc interfaces on the GPEH's behavior, with a focus on the threshold of galloping, power output, and induced electrical damping.
91 citations
10 Dec 2015
TL;DR: In this paper, the reliability and durability of a bimorph piezoelectric cantilever with a seismic mass at its tip is investigated. And the authors propose a new accelerated methodology and an associated test bench where the environment and stimuli can be precisely controlled over a wide period of time, which will allow the identification of potential failure modes and the study of their impacts by the way of direct mechanical investigation.
Abstract: In this paper we propose an approach to study the reliability of piezoelectric structures and more precisely energy harvesting micro-devices dedicated to autonomous active medical implants (new generation pacemakers). The structure under test is designed as a bimorph piezoelectric cantilever with a seismic mass at its tip. Good understanding of material aging and mechanical failure is critical for this kind of system. To study the reliability and durability of the piezoelectric part we propose to establish a new accelerated methodology and an associated test bench where the environment and stimuli can be precisely controlled over a wide period of time. This will allow the identification of potential failure modes and the study of their impacts by the way of direct mechanical investigation based on stiffness and blocking force measurements performed periodically.
1 citations
Patent•
17 Jul 2015TL;DR: In this article, an electronic device with electrical supply circuit (12m), with variable capacitor (11, 211, Cv) varying through alternating mechanical movement (10), is described.
Abstract: The invention relates to an electronic device with electrical supply circuit (12m), with variable capacitor (11, 211, Cv) varying through alternating mechanical movement (10). The supply comprises, in the form of passive components and with no means of synchronization: - generating branch (21) comprising in series the variable capacitor and a bias capacitor (212, C1), which is wired in parallel with a rectifying circuit (23, 23') and a storage branch (24), between: • base node (NB), on the variable capacitor side, • an output node (S), on the bias capacitor side (211, C1); - unidirectional charge return branch (22): • to the generating branch, through a bias node (P) between variable capacitor and bias capacitor, • from the rectifier, receiving part of the electrical energy produced; the circuit comprises a voltage multiplier (MT) connected to the bias node (P) so as to apply a voltage multiplied with respect to that existing in between the output node, and - the base node (NB) or one (OUT) of the ends of the storage branch.
1 citations
Patent•
24 Jun 2015
TL;DR: In this paper, an injection device of curing cement for percutaneous vertebroplasty is presented, comprising a system consisting of a pipe connecting the injection device to a percussive needle and a passive heat exchanger on the needle.
Abstract: The object of the present invention is an injection device (1) of curing cement (12) for percutaneous vertebroplasty, said device(l) comprising a system (7,8) for generating volumetric flow of said cement (12), and a pipe (17) connecting said injection device (1) to a percutaneous needle (14), said injection device (1) further comprises at least one active heat exchanger (13) located on the pipe (17) for dynamic controlled heating and/or cooling of said cement (12) during the injection, and a passive heat exchanger on the syringe (7)
01 Jan 2015
Patent•
17 Jul 2015TL;DR: In this article, an electronique avec circuit d'alimentation electrique (12m), a condensateur variable (11, 211, Cv) par mouvement mecanique alternatif (10).
Abstract: L'invention concerne un dispositif electronique avec circuit d'alimentation electrique (12m), a condensateur variable (11, 211, Cv) par mouvement mecanique alternatif (10). L'alimentation comprend, sous forme de composants passifs et sans moyen de synchronisation : - branche de generation (21) comprenant en serie le condensateur variable et un condensateur de polarisation (212, C1), branchee en parallele avec un circuit de redressement (23, 23') et une branche de stockage (24), entre : o un nud de base (NB), cote condensateur variable, o un nud de sortie (S), cote condensateur de polarisation (211, C1); - branche de retour de charge (22) unidirectionnelle : o vers la branche de generation, par un nud de polarisation (P) entre condensateur variable et condensateur de polarisation, o depuis le redresseur, recevant une partie de l'energie electrique produite; Le circuit comprend un multiplicateur de tension (MT) connecte au nud de polarisation (P) pour appliquer une tension multipliee par rapport a celle existant entre le nud de sortie, et - le nud de base (NB) ou l'une (OUT) des extremites de la branche de stockage.
27 Apr 2015
TL;DR: In this paper, an acoustic sound absorbing surface made of commercial Visaton™ K16 microspeakers is presented, which is made of a circular surface composed of a 10 cm diameter fix support with 7 embedded micro-speakers covering 8.5% of the overall surface.
Abstract: In this work, the fabrication of an acoustic sound absorbing surface (i.e. liner) made of commercial Visaton™ K16 microspeakers is presented. The acoustic liner is made of a circular surface composed of a 10 cm diameter fix support with 7 embedded microspeakers covering 8.5% of th overall surface. Different electrical connections of the microspeakers using no added electronic circuit are tested and the obtained absorption coefficient is 0.2 close to the natural resonance frequency of the microspeakers. A Negative Impedance Converter is used to electrically compensate the losses occurring in the acoustic liner. The maximum sound absorption is raised to 0.31 using the NIC again close to the natural resonance frequency of the microspeakers with a 7 microspeakers configuration covering 8.5% of the wall surface. The back cavity of the microspeakers is found to slightly move the maximum absorption peak but not to modify the maximum absorption. The influence of the microspeakers density is measured in open circuit configuration. The surface covered by the microspeakers ranges from 2.85% up to 12.35% of the wall surface. The maximum sound absorption ranges then from 0.1 to 0.34.