A simplified physical model, which described the generation of sound by a Helmholtz resonator upon flow excitation at its neck, was developed in the present investigation to study the drop in sound power transmission loss across such a resonator mounted on the wall of a duct conveying a low Mach number mean flow. Experiments were derived to validate the model. Mitigation methods derived accordi...

Global active noise control has been obtained on the tonal noise from a small centrifugal blower, similar to those used in laptop computers. Compact control systems were investigated for two configurations. The blower was mounted in both a short rectangular duct and in a mock laptop case that was modeled as a two-dimensional rectangular enclosure. Secondary sources and error sensors were locate...

Renewable energy sources include solar, wind, hydro, geothermal and biomass. Furthermore, ocean is being rapidly harnessed worldwide. In this study, to establish a suitable design method for various bidirectional ducted tidal turbines, instead of using blade element momentum theory CFD, which have been used previously, the turbomachinery was designing turbines. A turbine optimises equipment red...

Electrohydraulic lithotripsy of human gall stones was investigated in vitro in a bath of saline and in a saline perfused bile duct. The technique was effective--only two stones could not be shattered. Electrohydraulic lithotripsy power requirement correlated with mechanical strength of stones, but not with biochemical composition. A trend toward higher power requirement was recorded with larger...

aim : to assess the complications of bile duct injury in laparoscopic cholecystectomy in loghman medical center, tehran. background : the incidence of complications of laparoscopic cholecystectomy has increased dramatically since the introduction and widespread use of laparoscopic cholecystectomy.  patients and methods : from january 1998 to january 2002, a total of 155 laparoscopic cholecystec...

R. Eric Phelts, Ph.D., is a research engineer in the Department of Aeronautics and Astronautics at Stanford University. He received his B.S. in Mechanical Engineering from Georgia Institute of Technology in 1995, and his M.S. and Ph.D. in Mechanical Engineering from Stanford University in 1997 and 2001, respectively. His research involves signal deformation monitoring techniques and analysis fo...

objective: alveolar ridge preservation in patients with inadequate bone volume is one treatment option for successful implant placement and can be done by using bone graft materials. on the other hand, ceno bone has been recently produced by hamanand saz baft kish co. as a bone bioimplant of allograft origin. this study aimed to assess the clinical, histologic and histomorphometric results of b...

capsular contraction is a frequent complication following breast augmentation. on the other hand, capsular weakness, a not widely recognized complication, may occur around the implant. a weak capsule allows the migration of the prosthesis to the lateral region of the thoracic region or inferiorly, towards the abdomen, due to gravitational forces. the cause of capsular weakness remains unresolve...

The design of a new filter-type is presented that allows a sufficient reduction of in-duct aero-acoustic noise. The filter is a hybrid design containing a lined duct section based on the so called Cremer impedance and a section with combinations of micro-perforated plates. The Cremer impedance section strongly damps the zero-order or plane wave mode while the MPP section which breaks the circum...

In this research, a comparison of the relevance vector machine (RVM), least square support vector machine (LSSVM) and the radial basis function neural network (RBFNN) for evaporation duct estimation are presented. The parabolic equation model is adopted as the forward propagation model, and which is used to establish the training database between the radar sea clutter power and the evaporation ...