Search results for "Mechanical wave"
showing 10 items of 14 documents
Physical methods to promote drug delivery on mucosal tissues of the oral cavity.
2013
Introduction: The successful of drug delivery through the mucosal tissue of the oral cavity represents a current challenge as well as a great future perspective. The need for more rapid onset of action and improved absorption of medications has resulted in great development of drug delivery technologies that use physical methods to overcome the barrier properties of oral mucosae. Areas covered: This review discusses the various physical techniques which have been, and are being, explored to sustain drug delivery in the oral cavity. In particular, supersaturation, eutectic formation, iontophoresis, electroporation, sonophoresis, laser radiation, photomechanical waves, and needleless injectio…
Scattering and Localization of Classical Waves Along a Wave Guide with Disorder and Dissipation
1993
The problem of localization of classical waves has recently attracted consider-able attention.1,2 Classical waves have, of course, been the subject of extensive research already in the last century, as emphasized by Landauer in his historical sketch.3 A variety of interesting phenomena is associated with classical waves like seismic waves, tidal waves, acoustic as well as optical waves. A major topic is the transport of energy or information by these waves. The current interest in classical waves is stimulated by the development of microelectronics with its very small structures, in particular very thin wires (as connections between the components of integrated circuits) which may (or may n…
Surface-acoustic-wave-induced space-charge waves in electron–hole systems
2005
Abstract Space-charge waves in an electron–hole system are studied, which are excited by a moving grating provided by a surface acoustic wave (SAW). The SAW induces a constant current that may change its sign, when a constant electric field is applied opposite to the wave propagation direction. Current resonances are predicted to appear, when the SAW wavelength and frequency match the ones of the space-charge wave.
Collisions and Mechanical Wave Propagation in Elastic Rods
2011
Some results from experiments intended to measure the propagation speed of sound waves produced by collisions between small bodies and metallic rods are analysed. Elementary models of elastic collision and of the reflection and transmission of waves at media boundaries are discussed and tested with experimental data, in the framework of a workshop on mechanical wave propagation that featured at the University of Palermo in a two-year graduate programme for prospective physics teachers and in courses for undergraduate engineering and physics students.
A Problem Based Approach to Elastic Wave Propagation: The Role of Constraints
2009
A problem-based approach to the teaching of mechanical wave propagation, focused on observation and measurement of wave properties in solids and on modelling of these properties, is presented. In particular, some experimental results, originally aimed at measuring the propagation speed of sound waves in metallic rods, are used in order to deepen the role of constraints in mechanical wave propagation. Interpretative models of the results obtained in the laboratory are built and implemented by using a well-known simulation environment. The simulation results are, then, compared with experimental data. The approach has been developed and experimented in the context of a workshop on mechanical …
Waves Propagation in Turbulent Superfluid Helium in Presence of Combined Rotation and Counterflow
2010
A complete study of the propagation of waves (namely longitudinal density and temperature waves, longitudinal and transversal velocity waves and heat waves) in turbulent superfluid helium is made in three situations: a rotating frame, a thermal counterflow, and the simultaneous combination of thermal counterflow and rotation. Our analysis aims to obtain as much as possible information on the tangle of quantized vortices from the wave speed and attenuation factor of these different waves, depending on their relative direction of propagation with respect to the rotation vector.
ELASTIC WAVES: MENTAL MODELS AND TEACHING/LEARNING SEQUENCES
2006
In last years many research studies have pointed out relevant student difficulties in understanding the physics of mechanical waves. Moreover, it has been reported that these difficulties deal with some fundamental concepts as the role of the medium in wave propagation, the superposition principle and the mathematical description of waves involving the use of functions of two variables. In the context of pre-service courses for teacher preparation a teaching/learning (T/L) sequence based on using simple RTL experiments and interactive simulation environments aimed to show the effect of medium properties on the propagation speed of a wave pulse, has been experimented. Here, preliminary resul…
Measuring longitudinal wave speed in solids: two methods and a half
2006
Three methods to analyse longitudinal wave propagation in metallic rods are discussed. Two of these methods also prove to be useful for measuring the sound propagation speed. The experimental results, as well as some interpretative models built in the context of a workshop on mechanical waves at the Graduate School for Pre-Service Physics Teacher Education, Palermo University, are described. Some considerations about observed modifications in trainee teachers' attitudes to utilizing physics experiments to build pedagogical activities are discussed.
The nonlinear Schrodinger equation and the propagation of weakly nonlinear waves in optical fibres and on the water surface
2015
International audience; The dynamics of waves in weakly nonlinear dispersive media can be described by the nonlinear Schrödinger equation (NLSE). An important feature of the equation is that it can be derived in a number of different physical contexts; therefore, analogies between different fields, such as for example fiber optics, water waves, plasma waves and Bose–Einstein condensates, can be established. Here, we investigate the similarities between wave propagation in optical Kerr media and water waves. In particular, we discuss the modulation instability (MI) in both media. In analogy to the water wave problem, we derive for Kerr-media the Benjamin–Feir index, i.e. a nondimensional par…
Dyakonov surface waves in lossy metamaterials
2015
We analyze the existence of localized waves in the vicinities of the interface between two dielectrics, provided one of them is uniaxial and lossy. We found two families of surface waves, one of them approaching the well-known Dyakonov surface waves (DSWs). In addition, a new family of wave fields exists which are tightly bound to the interface. Although its appearance is clearly associated with the dissipative character of the anisotropic material, the characteristic propagation length of such surface waves might surpass the working wavelength by nearly two orders of magnitude. This research was funded by the Spanish Ministry of Economy and Competitiveness under the Project TEC2013-50416-E…