نتایج جستجو برای: mechanical vibrations
تعداد نتایج: 250112 فیلتر نتایج به سال:
We postulate that an equivalent continuum structure (ECS) of a single-walled carbon nanotube (SWCNT) is a hollow cylinder with mean radius and length equal to that of the SWCNT, and find the thickness of the ECS so that its mechanical response in free vibrations is the same as that of the SWCNT. That is, for mechanical deformations, the ECS is energetically equivalent to the SWCNT. We use MM3 p...
The role of promoting vibrations in enzymic reactions involving hydrogen tunnelling is contentious. While models incorporating such promoting vibrations have successfully reproduced and explained experimental observations, it has also been argued that such vibrations are not part of the catalytic effect. In this study, we have employed combined quantum mechanical/molecular mechanical methods wi...
The outstanding progress in nanostructure fabrication and cooling technologies allows what was unthinkable a few decades ago: bringing single-mode mechanical vibrations to the quantum regime. The coupling between photon and phonon excitations is a natural source of nonclassical states of light and mechanical vibrations, and its study within the field of cavity optomechanics is developing lightn...
Triggering large-scale motion by imposing vibrations to a system can be encountered in many situations, from daily-life shaking of saltcellar to silo unclogging or dynamic earthquakes triggering. In the well-known situation of solid or granular friction, the acceleration of imposed vibrations has often been proposed as the governing parameter for the transition between stick-slip motion and con...
Hyoscyamus reticulatus is an important medicinal plant belonging to Solanaceae family. This herb has antispasmodic, antichlorogenic and analgesic characteristics due to tropane alkaloids such as hyoscyamine and scopolamine. Mechanical vibration is one of abiotic stresses which could affect on growth and development of plant cells. In this research, effect of high-frequency mechanical vibration ...
Food webs involving plants, herbivorous insects and their predators account for 75% of terrestrial biodiversity (Price 2002). Within the abundant arthropod community on plants, myriad ecological and social interactions depend on the perception and production of plant-borne mechanical vibrations (Hill 2008). Study of ecological relationships has shown, for example, that termites monitor the vibr...
Many advanced techniques have been developed for diagnosis of machine faults caused by vibration. They are effective if the inspected vibration is well isolated from interference caused by vibrations from adjacent components. However, the components of manufacturing machines are numerous, small, and packed closely together. Thus the signal collected by a sensor is the aggregate of vibrations fr...
Lundström, Ronnie, 1985. Vibration exposure of the glabrous skin of the human hand. Umeå University, Medical Dissertions, New Series, 136. An occupational exposure to hand-arm vibration can cause a complex of neu rological, vascular and musculo-skeletal disturbances, known as the 'vibra tion syndrome'. However, the underlying pathophysiological mechanisms are not at all clear. Early signs of ...
The main objective of this study is to reduce optimal vibration suppression of Timoshenko beam under non-periodic step and impulse inputs. Cantilever beam was modeled by Timoshenko theory and finite element numerical method. Stiffness (K), mass (M), and damping (C) matrices are extracted. Then, in order to control structure vibration, piezoelectric patches were used due to simultaneous dual beh...
In this study, constraint groove pressing (CGP) process and ultrasonic assisted CGP (UCGP) process were investigated on the process forces, mechanical properties of the sheet, including hardness and tensile tests and grain size. Pure copper sheets were used as samples in this research. Samples were tested both with and without ultrasonic vibrations for mechanical properties and grain size up to...
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