Search results for " vibration"
showing 10 items of 296 documents
On modelling and stability of axially moving viscoelastic materials
2013
Random vibration mitigation of beams via tuned mass dampers with spring inertia effects
2019
The dynamics of beams equipped with tuned mass dampers is of considerable interest in engineering applications. Here, the purpose is to introduce a comprehensive framework to address the stochastic response of the system under stationary and non-stationary loads, considering inertia effects along the spring of every tuned mass damper applied to the beam. For this, the key step is to show that a tuned mass damper with spring inertia effects can be reverted to an equivalent external support, whose reaction force on the beam depends only on the deflection of the attachment point. On this basis, a generalized function approach provides closed analytical expressions for frequency and impulse res…
The Effectiveness of Physical Exercise on Bone Density in Osteoporotic Patients
2018
Physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients. The authors reviewed the current literature to define the most appropriate features of exercise for increasing bone density in osteoporotic patients. Two types emerged: (1) weight-bearing aerobic exercises, i.e., walking, stair climbing, jogging, and Tai Chi. Walking alone did not appear to improve bone mass; however it is able to limit its progressive loss. In fact, in order for the weight-bearing exercises to be effective, they must reach the mechanical intensity useful to determine an important ground reaction force. (2) Strength and resistance exercises: these are carried out with…
The Therapeutic Effects of Whole-Body Vibration in Patients With Fibromyalgia. A Randomized Controlled Trial
2021
Fibromyalgia is a chronic pain disease with few effective therapeutic options. We evaluated the efficacy of a 12-weeks therapy program that involves the use of whole body vibration in patients with fibromyalgia. The experimental group (N = 20 patients) participated in a neuromuscular training with a rotational whole body vibration platform for 12 weeks. The control group (N = 20 patients) received no physiotherapy treatment. The following variables were assessed before, after and 3 months after the therapy program: Fibromyalgia impact questionnaire, pain intensity, quality of life, sensitivity measurements (pressure pain thresholds, vibration thresholds), motor function tasks (Berg scale, 6…
Medical and occupational preconditions for vibration-induced spinal disorders: occupational disease no. 2110 in Germany.
1994
The current state of scientific knowledge of the biodynamic behaviour of the vertebral column under the influence of whole-body vibration whilst sitting and results from epidemiological studies caused the medical board of experts on occupational health of the Federal Ministry of Labour in Germany to add a new occupational disease to the official list of occupational diseases. The occupational disease “diseases of the lumbar spine from disc degeneration caused by long-term (mainly vertical) whole-body vibration exposure” has been introduced. The medical preconditions with the symptoms and the diagnostic methods are presented. With regard to the occupational preconditions for the acknowledgem…
Nonlinear vibrations of elastic beams with external general visco-elastic devices
2011
Assessing the Open Trenches in Screening Railway Ground-Borne Vibrations by Means of Artificial Neural Network
2009
Reducing ground borne vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied; among these open trenches are very effective. This paper deals with the study of the effect, in terms of reduction of vertical and horizontal displacements and velocities, of the open trenches. 2D FEM simulations have been performed and several open trench configurations have been analysed varying the main geometric features such as width and depth, distance from the rail, thickness of the soil layer over the rigid bedrock, type of the ground, ratio between the depth of the trench, and the thickness of the soil layer. For quantifying t…
Study of the effectiveness of the open trenches in reducing railway ground-borne vibrations: sensitivity analysis of its geometric features using art…
2009
Conformational-Dependent Photodissociation of Glycolic Acid in an Argon Matrix
2023
Ultraviolet-induced photodissociation and photo-isomerization of the three most stable conformers (SSC, GAC, and AAT) of glycolic acid are investigated in a low-temperature solid argon matrix using FTIR spectroscopy and employing laser radiation with wavelengths of 212 nm, 226 nm, and 230 nm. The present work broadens the wavelength range of photochemical studies of glycolic acid, thus extending the understanding of the overall photochemistry of the compound. The proposed kinetic model for the photodissociation of glycolic acid proceeds from the lowest energy conformer (SSC). The model suggests that ultraviolet light induces isomerization only between the SSC and GAC conformers and between …