The static pull-in instability of beam-type micro-electromechanical systems is theoretically investigated. Two engineering cases including cantilever and double cantilever micro-beam are considered. Considering the mid-plane stretching as the source of the nonlinearity in the beam behavior, a nonlinear size-dependent Euler-Bernoulli beam model is used based on a modified couple stress theory, c...

This paper examines the pull-in behavior of a bio-mass sensor with a cantilevered CNT actuated electrostatically by considering rippling deformation. Although this phenomenon can remarkably change the behavior of CNT, its effect on the performance of a CNT-based mass sensor has not been investigated thus far. This investigation is based on modified Euler-Bernoulli beam theory and rippling effec...

conclusions elective gastric pull up can be performed for children who are not above 10 kg. in such settings, the risk of respiratory infections and other complications would be significantly reduced because of shorter duration of intubation. results the mean age was 5 ± 2 years in patients who were above 10 kg and 3 ± 1 years in those less than 10 kg. patients who were less than 10 kg had shor...

this article analyses the push and pull factors that bring visitors to the iranian national parks. the study used a structured questionnaire to collect data on these factors and the socio-demographic profile of the visitors. survey conducted in boujagh national park, an area of 3177 hectares located in the north of the iran, produced 400 questionnaires. the factor analysis identified four push ...

Jump and pull-in instability are common nonlinear dynamic behaviors leading to the loss of performance reliability structural safety electrostatic micro gyroscopes. To achieve a better understanding these initial-sensitive phenomena, dynamics gyroscope system considering nonlinearities stiffness forces explored from global perspective. Static analyses performed estimate threshold detecting volt...

there are many techniques for reconstruction after total pharyngolaryngoesophagectomy. the use of a transposed stomach to restore gastrointestinal continuity, and this combined cervical and abdominal approach for pharyngolaryngoesophagectomy and gastric pull up has become one of the most popular. this retrospective study is a review of 50 consecutive iranian patients who underwent pharyngolaryn...

This paper investigates the parametric excitation of a micro-pipe conveying fluid suspended between two symmetric electrodes. Electrostatically actuated micro-pipes may become unstable when the exciting voltage is greater than the pull-in value. It is demonstrated that the parametric excitation of a micro-pipe by periodic (ac) voltages may have a stabilizing effect and permit an increase of the...

In the present work the pull-in voltage of a micro cracked cantilever beam subjected to nonlinear electrostatic pressure was studied. Two mathematical models were employed for modeling the problem: a lumped mass model and a classical beam model. The effect of crack in the lumped mass model is the reduction of the effective stiffness of the beam and in the beam model; the crack is modeled as a m...

The static pull-in instability of beam-type micro-electromechanical systems is theoretically investigated. Two engineering cases including cantilever and double cantilever micro-beam are considered. Considering the mid-plane stretching as the source of the nonlinearity in the beam behavior, a nonlinear size-dependent Euler-Bernoulli beam model is used based on a modified couple stress theory, c...