Semiactive type

The mass damper systems are classified into four types from the energy supply point of view the passive type (TMD), semiactive type (SAMD), full active type (AMD) and hybrid (HMD). The TMD is effective if the natural period of the device is tuned well to that of the tall building (mostly the fundamental mode). However, if the period of the device or the building gets changed, or the predominant period of the building response differs from the period of the device, the effectiveness of the TMD cannot be maintained. Therefore the other three types are developed to solve this problem. The... 

A damper with a fixed damping coefficient will not be able to achieve a similar performance as the presented control method. The best response in far field type earthquakes is established by minimum damping with an extra control force at some time instances near field type earthquakes, on the other hand, appear to be best handled with a fixed base. Therefore, in either case a fixed valued damper will not suffice to produce a desirable structural response. At last, a smartly controlled semiactive damper is able to protect a seismically isolated building from both near and far field type earthquakes. 

Type B SCC includes a large munber of passive systems in which cracking is induced by chloride ions. All these systems share an acid crack environment and an active or semiactive state at the crack tip. For a while it was thought that Al-Li-Cu-Mg alloys might be an exception to this rule because alkaline crack chemistries are possible under special conditions (little or no cathode area outside the crack), but it soon became clear that rapid cracking in this system is associated with acidification in the crack [120,121]. 

ER fluid-controlled engine mount, 343 ER fluid-controlled semiactive damper, 344 ER fluids, 311-22 classification, 313 experimental configuration, 312 ion exchange resin-type, 325 mechanisms, 312 nonwater-containing, 343 operation, 312 resistance, 342... 

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