For example, electromagnetic, electrostatic, electrostrictive and magnostrictive transduction technology can be used. Accordingly, there still exists a need for an apparatus able to be used with a piezo material to improve the harvesting of vibration energy at low frequencies, and also at frequencies above and below the resonant frequency of the structure from which vibration energy is being harvested. The apparatus 10 has a significantly lower frequency of operation than a conventional energy harvesting device, such as that shown in FIG. 7. The biasing element 208 acting on the free end 206 of the beam 204 significantly amplifies the displacement over what would be achieved without the biasing element 208 acting on the free end 206 of the beam 204. When the polarity of the voltage applied to the piezoelectric layers 210 and 214 is changed, this causes the layers 210 and 214 to deflect the beam 204 into the second stable position shown in FIG.
60/491,122 filed Jul. 30, 2003, the disclosures of which are incorporated herein by reference.
1. A reaction mass is attached to the tip of the beam to increase performance. A significant benefit of the present apparatus is that it can be used over a wider frequency bandwidth than previously developed VEH devices incorporating a tip mass on the free end of the piezo flexure. 1 is used, the stiffness of the beam, including the piezo material, beam length (L) and the tip mass determine the lowest frequency where the VEH device will work. 60/491,122 filed Jul. 30, 2003, the disclosures of which are incorporated herein by reference. Ser. No. 11/344,823, filed Feb. Referring to FIG. 12, an apparatus 400 in accordance with an alternative embodiment of a drive motor is illustrated. The beam includes at least one piezoelectric layer of material on one of its surfaces, and in one embodiment at least one layer of piezoelectric material on each opposing surface of the beam.
Apparatus 400 includes a support structure 402 having a pair of leaf springs 402 a for providing the compressive force on a recurve beam 404. The beam 404 is otherwise identical in construction with beam 304 described in connection with FIG. Que medicamento es bueno para dolor de espalda . The limitation of needing to “tune” the system around the resonant frequency of the cantilever beam imposes a significant limitation in terms of efficient operation of the system shown in FIG. All forms of active flow control require some form of actuator or motor to energize a flow control element, to thus modify or change the airflow within the viscous boundary layer. For example, the apparatus 10 is extremely well suited to applications requiring large deflections of the piezo flexure and low force, such as with an aerodynamic flow control synthetic jet actuator or a low frequency audio speaker.
This relationship, when applied to the apparatus 10, results in two stable angles. The biasing element 208 has one end that is fixedly secured to a second upright 202 b via any suitable mechanical coupling, hinge, flexure, or by adhesives. The biasing element 208 is coupled to the free end 206 of the beam 204 by a flexible coupling, or hinge, or rigid attachment such as a weld or clamp. When properly matched, the apparatus 10 is highly efficient. The apparatus thus forms a means to significantly “soften” a piezo flexure which enables the piezo flexure to be used in low frequency vibration energy harvesting applications where such a flexure would otherwise be too structurally stiff to harvest the vibration energy. While the apparatus 10 has been described in connection with “softening” a piezo flexure for vibration energy harvesting applications, it will also be appreciated that the apparatus 10 can be readily incorporated in an actuator.
- Té pu erh, té pu’erh tuocha, té del Palacio de Pu’erh
- Pueden tener efectos hipoglicemiantes en pacientes diabéticos
- Repítelo todos los días hasta que desaparezca el problema
- Síndrome del túnel carpiano
- Compresas con té de cáscaras de naranja
- Cuando tenga que agacharse, no lo haga con las piernas rectas, dóblelas
- Terapia breve centrada en soluciones
- More easily recoverable in case of catastrophic failure, with the exception of sinking
A significant advantage of the apparatus 200 is that the amplitude displacement of the free end 206 of the beam 204 is significantly greater than with previous piezoelectric actuator configurations, and especially so at frequencies below the natural oscillation frequency of the beam 204. This is in large part due to the effective softening of the beam 204 caused by application of the bias force. The compressive biasing force provided by the biasing element assists this movement and helps to deflect the free end (i.e., tip end) of the beam fully into the first stable position as the beam leaves its second stable position. The end 205 is fixedly coupled to a first upright support 202 a of the support structure 202 by adhesives, mechanical coupling via fasteners, or any other secure means of attachment. The piezo flexure 12 includes piezo electric layers 16 and 18 formed on opposite sides of a flexible supporting substrate 20. The substrate 20 includes an end 22 which is fixedly coupled to the structure 14. The substrate 20 can be plastic, metal or any other flexible material that allows the piezo electric layers 16 and 18 to be bonded thereto.