Passive damping systems

Selection from existing or innovative Construction Methods, Schedules and Designs to Adapt projects to the Latest Understanding of the Changing Risks due to Climate at each individual site (e.g., the passive damping system at the Taipei Financial Center). 

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 ... 

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. 

The tuned mass damper (TMD) system is a typical form of control devices including a mass, spring, and a viscous fluid damper, which can be attached to the main structure at one of its degrees offreedom. This system is one ofthe well-accepted devices to control flexible structures, particularly, tall buildings. In this passive control system, if its damping ratio or stiffness of the spring changes with time, then it is called a semi-active tuned mass damper (STMD). 

Alhan, C., Gavin, H. (2004). A parametric study of linear and nonlinear passively damped seismic isolation system for buildings. Engineering Structures, 24, 485-497. doi 10.1016/j. engstmct.2003.11.004... 

Semi Active Tuned Mass Damper (STMD) In passive TMD system, if its damping ratio or stififiiess of the spring changes with time, then it is... 

Lever arms (Figure Ic) are proposed to increase the efficiency of damping devices by magnifying the inter-story drifts and drift velocities, transferred from the structure to dampers (Gluck, 1996). This idea was further developed for design of structures with optimal viscous dampers (Ribakov, 2000). The equivalent lever arm approach is used to change the effect of off the shelf linear viscous devices yielding an optimal passive control system. 

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. 

Symans MD, Constantlnou MC (1998) Passive and fluid viscous damping systems for seismic energy dissipation. ISET J Earthq Technol 35(4) 185-206... 

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... 

A passive device, as is the case for dampers, may only absorb energy from the system. That is why the damping force can only act in the opposite direction of its velocity. Hence, if the calculated optimum damping cmistant has a negative sign, the required force will not be producible. In this case, the damping constant will take its minimum value of 5,000 Ns/m. In addition a numerical precaution is taken to prevent a divide by zero error. During the calculation of the optimum damper constant, the smallest absolute damper velocity is limited to 1 mm/s. This does not have a detrimental effect to the structural response, since the worst case causes a force of 25 N only. 

Consider an n story linear shear-type building structure, equipped with r passive energy dissipation systems in various story units. Masses, stiffnesses and damping coefficients for different floors of the building are contained in (nxn) matrices, respectively called M, K, C. 

Semi-Active (Adaptive-Passive) Systems Refer to an adjustable passive vibration control scheme, that is, the passive treatment can adjust itself in response to changes in the structure. For example, the stiflfiiess, damping coefficient or other variables of the passive control scheme can change automatically so that optimal vibration mitigation is induced. These variable components, also known as tunable parameters of the control system, are re-tailored via a properly developed semi-active control algorithm. Being more versatile than passive control techniques and more affordable (in terms of cost and energy consumption) than active control schemes, has made semi-active control methods very popular. 

Passive Control Mechanical devices distributed through the structure to provide added damping to the system to reduce the response to controllable limits. 

Tuned Mass Damper (TMD) A passive vibration control device which is a single-degree-of-ffeedom system consisting of mass, damping, and stif iess components. 

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