Ducts are widely used in an industry field. For example, air conditioning ducts, exhaust smoke elimination ducts and silencers have been various ducts. In general, the a flow vortices generated duct sometimes cause resonance phenomenon self-sustained tone. Once occurs, high level sound is suppression of this strongly quickly required. It necessary to know natural acoustic frequency for examinat...

We describe a novel method for assessing stenosis severity based on pressure wave measurements. Pressure waves for several degrees of stenosis at different distances proximal to the stenosis were recorded from in vitro and in vivo models. Signal analysis was performed using power spectral density, and radial compliance was also measured. Pressure wave components at the acoustic frequency band (...

This paper discusses a discrete-time modeling technique where the length of time delays can be arbitrarily adjusted. The new system is called a fractional delay waveguide model (FDWM). Formerly, FDWMs have only been implemented with FIR-type fractional delay filters. We show how an FDWM can be implemented using allpass filters. We use low-order allpass filters that are maximally-flat approximat...

in order to evaluate the effectiveness of the iranian made charcoal tubes in the field , 60 local made and 60 imported ones (skc type) were randomly selected and placed side by side for sampling aromatic hydrocarbons (including benzene, toluene, xylene) in workers breathing zone in a paint factory. the results indicated that there were no statistically significant differences between the mean c...

acoustic neuromas (an) are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(vs) causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. in many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by mri. in the majority of cases the tumor is s...

ultraviolet waves, because of their short wavelength, have a high energy and considerable damaging effects on surfaces. protection against ultraviolet radiations is one of the finishing treatments done on surfaces exposed to sunlight. the importance of this issue in relation to human health, due to complications such as skin burns and cancer, is doubled. up to now, different materials such as z...

Research on new techniques of single-chamber mufflers hybridized with an internal extended tube has been addressed; however, the research work on a space-constrained multi-chamber muffler hybridized with multiple internal extended tubes which may increase the acoustical performance within a specified back pressure has been ignored. Therefore, the analysis of a sound transmission loss (STL) for ...

The ANTARES Neutrino Telescope [1] is a water Cherenkov detector currently under construction in the Mediterranean Sea. It is also designed to serve as a platform for investigations of the deep-sea environment. In this context, the ANTARES group at the University of Erlangen will integrate acoustic sensors within the infrastructure of the experiment. With this dedicated setup, tests of acoustic...

Thermal ablation is an interventional technique that promises to enable percutaneous treatment of many cancers and other disorders throughout the human body. Acoustic ablation offers the possibility of steering thermal energy electronically [1], and is known to be MRI compatible, and thus amenable to real-time thermal dose monitoring through MR thermometry. We propose a pneumatically actuated r...

This research presents a model of the avian vocal tract, implemented using waveguide synthesis and numerical methods. The vocal organ of the songbird, the syrinx, has a unique topography of acoustic tubes (a trachea with a bifurcation at its base) making it a novel subject for waveguide synthesis. In the upper region of the two bifid bronchi lies a nonlinear vibrating membrane—the primary reson...