Active damping systems

Position/Displacement sensors can be used in active damping systems of industrial washing machines in order to compensate for vibrations coming from unbalanced drums /laundry. These can work much like a simple automotive shock absorber. 

Disc-shaped rotor with integrated active damping system... 

Fig. 7.20 Test stand for the damping petfoimanee investigation of the fiber-reinforced rotor with integrated active damping systems.

AFM operation requires a minimum of vibrations. These vibrations refer to not only building vibrations, but also vibrations caused by airflow, persons walking in the lab, and equipment, such as personal computers, the AFM controller, etc. To damp out vibrations, AFM scan units are typically placed on passive and/or active vibration damping systems, such as ... 

In summary, what we have described is a system which recovers from the transmitter pulse in two distinct steps. The first part takes place through some low impedance path usually, but not always, associated with the output circuitry of the transmitter. In order to improve the S/N, the transmitter circuit is passively disconnected by a set of series crossed diodes after which the second phase of recovery proceeds according to an active damping circuit which, if present, leads to better S/N because of the improved recovery even though it is a source of additional noise. Neither sets of... 

Damping systems do not isolate the structure from the vibration source, but instead reduce the magnitude of the vibration within the structure. There is damping technologies that are passive and active. In passive systems, vibrations are diverted into special materials or structural components that dissipate the vibration energy as heat. In active systems, an electronic system monitors the response of the structure to vibration, and actuators then move the structure in opposition to the vibration, effectively canceling it out. Active systems can achieve greater performance and control than passive systems, but are much more expensive, take up more space, and require power. 

Restriction of achievable feed bandwidth and performance capability of machines High stiffness and damping with low mass required Active vibration suppression by semi-active and active ancillary systems (e.g., adaptive mass damper, adaptive friction damper)... 

Active Vibration Reduction. An active vibration control system consists of a hydraulic or electrodynamic actuator, vibration sensor, and electronic controller designed to maintain the seat pan stationary irrespective of the motion of the seat support. Such a control system must be capable of reproducing the vehicle motion at the seat support, which will commonly possess large displacement at low frequencies, and supply a phase-inverted version to the seat pan to counteract the vehicle motion in real time. This imposes a challenging performance requirement for the control system and vibration actuator. Also, the control system must possess safety interlocks to ensure it does not erroneously generate harmful vilxation at the seat pan. While active control systems have been employed commercially to adjust the static stiffness or damping of vehicle suspensions, to improve the ride comfort on different road surfaces, there are currently no active seat suspensions. 

Adaptronics and control can be implemented at different points or subsystems. In order to evaluate possible concepts from a system point of view, an overall end to end model is established. The elements of such an integrated simulation model are shown in Fig. 5.3. In the left part the reduced structure (dynamics) model together with control laws are used for assessing the effects of active damping introduced by adaptronics as described below. The right part contains the optical submodel together with the telescope drives. 

Integrated safety, active crash systems Active pre-crash and crash systems, reversible locking systems, adaptation of car structure, increased deformation zone, load control, active damping... 

Electro- and magnetorheological fluids are mainly used in semi-active damping devices, current car suspension systems in premimn class vehicles based on MRF [139]. Furthermore, shape memory alloys are imder investigation, especially for active pre-crash systems [141]. 

For vibration reduction of panels mostly, semi-active vibration damping systems based on piezoelectric transducers have been studied. The piezos are attached to the structure and electrically shunted with resistor-inductor circuits. By proper tuning of the circuit elements, effects compared to the application of mechanical vibration absorbers can be observed, however only laboratory experiments have been performed yet [147]. 

Introducing an additional mass-stiffiiess-damping element at the mass to modify the Eigen frequeneies (Figure 3a). There may be passive masses or active or semi-active systems using e.g. eontrol to accelerate the mass to minimise the deflection of the mass niy Such mass-stifl iess-damping systems are called compensators, absorbers or tuned mass dampers. 

Some ovens are set with one central exhaust flue, whereas others may be designed to have ports at both the tunnel entrance and exit. A dedicated manometer or other vent sensor should be installed in each exhaust line to monitor setup and routine exhaust performance. Blast gates in the exhaust line permit flow adjustment. It is customary to mount vent sensors after the flow damping device. Follow oven manufacturer s guidelines for exhaust requirements. Since the exhaust gases are laden with volatile materials, mostly from the solder paste, active exhaust systems should be checked routinely for performance. Impeller blades can foul... 

Fig. 7.21 Damping performance of the integrated system. The integrated damping system has been activated in the 3rd second.

Active systems also include those that assist in compartmenting the fire such as fire door release mechanisms, fire shutters and mechanical damping systems. In addition other systems may be actively used for smoke extraction. 

A combination of passive and active control systems has been applied to USC University Hospital and includes five of the six buildings of the medical center. Both linear and high damping rubber bearings were chosen for the base isolation, to provide lateral stiffness. 

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