Both diagnostic and therapeutic ultrasound applications require an understanding of the directivity patterns on the transducers to design ultrasound equipment and faithfully characterize the acoustic output from medical ultrasound devices. Since each ultrasound transducer has its own specific directivity pattern, the measurement of the directivity pattern is necessary. The objectives of this wo...

Most of our understanding of earthquake rupture comes from interpretation of strongground-motion seismograms; however, near-rupture-tip fields of stress and particle motions are difficult to resolve. In particular, the decay of frictional resistance from a peak value at the leading tip of the rupture to a residual kinetic value and subsequent healing characterizes the earthquake process, yet th...

The aim of this research is to create a microphone array on a rigid sphere that could be used for teleconferences and for recording of music with the aim of five-channel loudspeaker surround sound reproduction. Experiments were undertaken, within a MATLAB environment, by running computer simulations that tested the directivity of a rigid sphere microphone array in both near and far field. The s...

For tele-conference systems or voice-controlled systems, the highquality sound capture of distant-talking speech is very important. However, background noise and room reverberations seriously degrade the sound capture quality in real acoustical environments. A microphone array is an ideal candidate for capturing distanttalking speech. With a microphone array, the desired speech signals can be a...

Abstract— This paper describes 2 x 2 triangular microstrip patch antenna using T-junction with quarter wave transformer. By regulating the distance in patch antenna and adjusting feed position, bandwidth can be obtained and by using an array, directivity is enhanced. The requirement of large bandwidth, high directivity, and minimum size leads to the design of 2 x 2 triangular microstrip patch a...

Geophysical techniques were employed to analyze one of the landslides that affected main access road Pujilí (Ecuador). A passive seismic technique was utilized test a total 70 horizontal vertical spectral ratio (HVSR) points, complemented by an active seismic-refraction profile and multichannel analysis surface waves (MASW) survey. The results from geophysical surveys facilitated determination ...

We report a high-directivity plasmon-resonant terahertz (THz) emitter (PRE) incorporating a 3D-integrated antenna complex. The emitter structure is based on a high electron mobility transistor having unique doubly interdigitated grating gates as a broadband THz antenna that can convert non-radiative plasmons to radiative electromagnetic waves. Due to the sub-wavelength aperture of practical gra...

This work presents a method to control the perceived distance of an auditory object by changing the directivity pattern of a loudspeaker and consequently the direct-to-reverberant ratio at the listening spot. Control of the directivity pattern is achieved by beamforming using a compact multi-driver loudspeaker unit. A small-sized cubic array consisting of six drivers is assembled, and per drive...

In this paper, the maximization of the directivity of compromise difference patterns in subarrayed monopulse linear array antennas with optimum sum mode is addressed by means of a two-stage excitation matching procedure. The knowledge of the independently optimum difference excitations, which provide the maximum directivity, is exploited with an efficient matching technique based on the contigu...