in this research a flat plate solar air collector was investigated under direct solar radiation consisted of a slatted glass cover, perforated absorber aluminum sheets (porosity 0.0177, 0.0314 and absorber thickness of 2.5 mm). the effect of porosity on absorber efficiency of collector was evaluated. six levels of air mass flow rates (0.0056 to 0.0385 kg m-2 s-1) were adopted.average solar ener...

outdoor experiments on a once-through single glazed solar air heater with perforated metal absorber plate were conducted to determine the practical effect of absorber plate porosity as well as suction air flow rate on the collector thermal efficiency and its total pressure drop. three aluminum absorber plates were made perforated by drilling circular holes with different diameter/pitch ratios i...

The possibility of employing internal wall as mass absorber in rectangular water storage tanks subjected to harmonic ground motion excitation is investigated in this paper. Internal walls are used in these tanks usually for service performance purposes, which could be used as mass absorber to control seismic demand on tank's exterior walls. Derivation of the response of the coupled system inclu...

Whenever a tuned-mass damper is attached to a primary system, motion of the absorber body in more than one degree of freedom (DOF) relative to the primary system can be used to attenuate vibration of the primary system. In this paper, we propose that more than one mode of vibration of an absorber body relative to a primary system be tuned to suppress single-mode vibration of a primary system. W...

Watts [1] in 1883 and Frahm [2] in 1909 reported on the first use of a dynamic vibration absorber. The range of industrial applications of such device is wide and includes the minimization of the rolling of ships, the damping of torsional vibration of internal combustion engines and the smoothing of vibrations in a barber cutter. The minimization of oscillations of tall buildings by means of dy...

In this work, a system consisting of a main structure with a nonlinear tuned vibration absorber having a hardening spring attached to it is considered. The nonlinearity in the absorber's spring is a cubic nonlinearity and is obtained by attaching two additional, relatively soft, similar linear springs to the absorber's mass. These added springs are attached to the absorber's mass in such a way ...

this paper presents a reduce roll vibration of the full vehicle model with passive suspension systems using vibration absorber to change the dynamic system matrix stat’s eigenvalue. since using the controller system has been splurged and required to energy consuming, in this research the vehicle body roll vibration has been reduced and supplied vehicle stability using a vibration absorber for t...

In this article, the H∞ optimization design of a hybrid vibration absorber (HVA), including both passive and active elements, for the minimization of the resonant vibration amplitude of a single degree-of-freedom (SDOF) vibrating structure is derived by using the fixed-points theory. The optimum tuning parameters are the feedback gain, the tuning frequency, damping and mass ratios of the absorb...

This study is concentrated on the natural frequencies and mode shapes of a simple three-member space frame coupled with a dynamic vibration absorber. The dynamic vibration absorber is modeled as a six-degree-of-freedom mass-spring system. For the first time, the free vibration of an elastic structure with a six-degree-of-freedom mass-spring system is found. Each member of the space frame has un...

A robust vibration absorber reduces vibrations of a system over a range of frequencies. Passive vibration absorption is achieved with a tuned mass and spring (known as a dynamic vibration absorber (DVA)). This is a simple, low cost method of reducing vibrations at a single frequency; however, in order to achieve robust absorption a heavy mass is required. Active vibration control is achieved wi...