Influences of various magnetospheric and ionospheric current systems on geomagnetically induced currents around the world

Ground-based observations of geomagnetic field (B field) are usually a superposition of signatures from different source current systems in the magnetosphere and ionosphere. Fluctuating B fields generate geoelectric fields (E fields), which drive geomagnetically induced currents (GIC) in technological conducting media at the Earth's surface. We introduce a new Fourier integral B field model of east/west directed line current systems over a one-dimensional multilayered Earth in plane geometry. Derived layered-Earth profiles, given in the literature, are needed to calculate the surface impedance, and therefore reflection coefficient in the integral. The 2003 Halloween storm measurements were Fourier transformed for B field spectrum Levenberg-Marquardt least squares inversion over latitude. The inversion modeled strengths of the equatorial electrojets, auroral electrojets, and ring currents were compared to the forward problem computed strength. It is found the optimized and direct results match each other closely and supplement previous established studies about these source currents. Using this model, a data set of current system magnitudes may be used to develop empirical models linking solar wind activity to magnetospheric current systems. In addition, the ground E fields are also calculated directly, which serves as a proxy for computing GIC in conductor-based networks

Microfabricated planar coils with high turns density: design and manufacturing

This work addresses the design and the fabrication of small scale square planar coils with high density of turns and self inductances up to 170 µH. First, the modified Wheelers formula is used to determine the optimal number of turns in order to achieve the highest inductance. Then, an effective process flow based on polyimide (PI) and copper processing is presented, and the key aspects of the processing are discussed. Finally, the fabricated coils are characterized both electrically and morphologically, and the results are compared to the model showing good agreement with the theoretical calculations

Influence of Piezoelectric Actuator Geometry on Resonant Vibrating Amplitude

Piezoelectric actuator has been used in different applications because of its compact structure compared to magnetic actuators. This paper reports the influence of piezoelectric actuators geometry on the plate vibrating amplitude. Through a Finite Element Method (FEM) approach, we find out the piezoelectric actuator surface area greatly affects the vibrating amplitude. Increasing the piezoelectric actuator surface can raise the plate displacement up to hundred micrometers. Besides, the piezoelectric actuator shape and orientation can be adjusted to increase the plate displacement for a fixed area. Finally, experiments on two prototypes with two piezoelectric actuators presenting different geometries are carried out to validate that the plate with greater piezoelectric actuator has bigger displacement than that with smaller piezoelectric actuator. The experimental and simulated plate displacements have a difference of around 25%

Microgénératrice pour pièce d'horlogerie et procédé de fabrication de microgénératrice pour pièce d'horlogerie

Microgénératrice (1) pour pièce d'horlogerie, la microgénératrice (1) comportant un rotor (3) avec au moins un aimant permanent (33, 33') et un stator (2) avec au moins une bobine (21) comportant une déposition de matière conductrice (212, 223) sur un substrat, ledit substrat (210) comportant une portion d'un wafer de silicium .La bobine (21) comporte plusieurs couches de matière conductrices superposées (212, 223) sur ledit wafer en silicium et séparées les unes des autres par une ou plusieurs couches isolantes (217)

Design of an Innovative Cylindrical Spring with a Negative Stiffness

Interest in the dielectric electroactive polymer is growing in the medical field because of the large similarity with the biological muscles. With the objective to create an artificial pump based on DEAP, this paper presents the concept of an innovative spring with a negative stiffness and radial displacement. It was demonstrated that coupling a spring with such characteristic and the DEAP allows to improve the performance of DEAP actuators. The final design is close to a stent with monostable beams instead of current bistable one. The complete spring is composed of several modules which include one beam and one rigid support. The radial displacement is induced by the tangential compression of each beams and the equations of deformations demonstrates that the radial displacement is increased if the number of modules is higher than 6. In the design procedure, relevant choices have allowed to reduce computation time of the FE simulation. The different equations are validated through FEM results and less than 1.5% of error is obtained. The proposed spring is finally coupled with a tubular dielectric electroactive polymer membrane in order to create a cylindrical actuator. The radial displacement is around 3 mm. The result has been validated through FEM and an error of 6.8% is obtained