Preliminary measurements and numerical predictions reveal that simple, and relatively small, horns generate remarkable amplification of acoustic particle velocity. For example, below 2 kHz, a 2.5 cm conical horn has a uniform velocity amplification ratio (throat-to-mouth) factor of approximately 3, or, in terms of a decibel level, 9.5 dB. It is shown that the velocity amplification factor depen...

this work presents a numerical analysis of entropy generation in γ-shaped enclosure that was submitted to the natural convection process using a simple thermal lattice boltzmann method (tlbm) with the boussinesq approximation.  a 2d thermal lattice boltzmann method with 9 velocities, d2q9, is used to solve the thermal flow problem. the simulations are performed at a constant prandtl number (pr ...

local site conditions have a strong effect on ground response during earthquakes. two important soil parameters that control the amplification effects of seismic motions by a soil column are the soil hysteretic damping ratio and shear wave velocity. this paper presents the results of in situ damping ratio measurements performed using continuous surface wave attenuation data at a site in semnan ...

The objective of this study was to determine the optimal assessment of arterial stiffness that relates to diastolic dysfunction. Forty-one patients had measurements of brachial-ankle pulse wave velocity (baPWV), carotid-femoral pulse wave velocity (cfPWV), ankle brachial index (ABI), pulse pressure (PP), and augmentation index (AIx). Diastolic dysfunction was evaluated by echocardiographic indi...

The alternating current electroosmotic flow of a non-Newtonian power-law fluid is studied in a circular microchannel. A numerical method is employed to solve the non-linear Poisson-Boltzmann and the momentum equations. The main parameters which affect the flow field are the flow behavior index, the dimensionless zeta potential and the dimensionless frequency. At very low dimensionless frequenci...

BACKGROUND AND PURPOSE Gait disturbances in the elderly are disabling and a major public health issue but are poorly understood. In this multimodal MR imaging study, we used 2 voxel-based analysis methods to assess the voxelwise relationship of magnetization transfer ratio and white matter hyperintensity location with gait velocity in older adults. MATERIALS AND METHODS We assessed 230 commun...

Sir, During a study ofchanges in afterload induced by the cold pressor test, Smith et al (1989;61:344-7) recognised a relation between heart rate and transmitral velocities derived from pulsed Doppler recordings. We specifically studied the relation between transmitral velocities and differing RR intervals during exercise and respiration in healthy men.'2We found a clear cut linear change in pe...

BACKGROUND AND PURPOSE Intracranial atherosclerotic disease is associated with a high risk of stroke recurrence. We aimed to determine accuracy of transcranial Doppler screening at laboratories that share the same standardized scanning protocol. METHODS Patients with symptoms of cerebral ischemia were prospectively studied. Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SON...

AIMS In this study, we aimed to assess left ventricular (LV) systolic and diastolic functions by tissue Doppler imaging (TDI) in patients with obstructive sleep apnoea syndrome (OSAS) and to investigate the effects of 6 month continuous positive airway pressure (CPAP) on LV systolic and diastolic functions. METHODS AND RESULTS We studied 28 new diagnosed moderate and severe OSAS patients (apn...

Snow drifting is a typical natural disaster, and an increasing importance has been attached to its theory research and field observation for the sake of cold region engineering. Numerical simulation, as an efficient method of studying snow drifting, promises to be widely applied in this field. In this paper, the finite element method is used to simulate the wind velocity field. Selected upwind,...