A VERSE algorithm with additional acoustic noise constraints
نویسندگان
چکیده
Introduction At higher static field strengths of 7T and above specific absorption rate (SAR) and acoustic sound pressure level (SPL) pose limitations on the pulse sequence design. To overcome SAR limitations, the VERSE principle can be used [1]. Here, the envelope of existing rf pulses are modified together with the shape of the slice-selection gradient to selectively reduce high B1 amplitudes during the (often central) portions of the rf pulse. With VERSE, a gradient amplitude modulation is introduced, that can cause additional noise in the pulse sequence. In this work a general VERSE algorithm is presented, that reduces both the B1 amplitude (and thus SAR) and the acoustic noise of the gradient for arbitrary RF pulses. The method is demonstrated for SINC rf pulses.
منابع مشابه
Acoustic correlated sources direction finding in the presence of unknown spatial correlation noise
In this paper, a new method is proposed for DOA estimation of correlated acoustic signals, in the presence of unknown spatial correlation noise. By generating a matrix from the signal subspace with the Hankel-SVD method, the correlated resource information is extracted from each eigen-vector. Then a joint-diagonalization structure is constructed of the signal subspace and basis it, independent...
متن کاملParallel implementation of underwater acoustic wave propagation using beamtracing method on graphical processing unit
The mathematical modeling of the acoustic wave propagation in seawater is the basis for realizing goals such as, underwater communication, seabed mapping, advanced fishing, oil and gas exploration, marine meteorology, positioning and explore the unknown targets within the water. However, due to the existence of various physical phenomena in the water environment and the various conditions gover...
متن کاملA comparison of LPC and FFT-based acoustic features for noise robust ASR
Within the context of robust acoustic features for automatic speech recognition (ASR), we evaluated mel-frequency cepstral coefficients (MFCCs) derived from two spectral representation techniques, i.e. the fast Fourier transform (FFT) and linear pre dictive coding (LPC). ASR systems based on the two feature types were tested on a digit recognition task using continuous density hidden Markov ph...
متن کاملThe Role of Trees in Absorption, Control and Reduction of Acoustic Pollution "Based on a Scientific Commentary of the Fourth Verse of Munafiqun Surah"
Scientific miracle is one of the aspects of miracle in the Holy Quran. The Holy Quran includes verses referring to scientific fact, those proved by development of human knowledge and scientific equipments after passing 14 centuries from the revelation of the Quran. The verse 4 of Munafiqun verse: "as though they were blocks of wood in striped cloaks" is among those verses which, based on a spec...
متن کاملNoise pollution analysis in Tehran cement plant
Background : Cement industry has many process units. Basically all of these units can be considered as a source of noise. Since noise pollution is defined based on its offensive hearing effects, the importance of the noise sources depends directly on the number of workers in the unit. Materials and Methods : An experimental study has been done at Tehran cement factory to recogn...
متن کامل