1. Introduction The Li intercalated polymorphs of titanium disulfide – the trigonal (layered) and the cubic modification – form a unique model system for comparison of Li self-diffusion in two and three dimensions, respectively, within two host structures of the same composition [1]. Slow Li + transport in cubic Li x TiS 2 (x = 0.6) was probed by 7 Li stimulated echo NMR spectroscopy (see, e. g...

R. G. Nunes, P. Jezzard, H. Johansen-Berg, T. E. Behrens, S. Clare FMRIB Centre, University of Oxford, Oxford, Oxfordshire, United Kingdom Synopsis: Interleaved Echo Planar Imaging (IEPI) can be used to produce high-resolution Diffusion-Weighted Images (DWI). However, DW makes the images particularly sensitive to patient motion, resulting in severe artefacts. These problems can be overcome by a...

Pulsed NMR is the most convenient and powerful technique for measuring diffusion, when it is applicable. Hahn (1) in a seminal paper laid the foundations of the technique. He showed that for a nuclear spin system that obeyed the Bloch equations (taking small liberties with exact details), a 9O.y T 180, RF pulse sequence produced a free induction decay (FID) and an echo, as pictured in Figure 1....

Talker echoes are one of the influencing factors which need to be addressed during migration of telecommunication towards wideband transmission. A recently carried out talking and listening test (TALT) focusing on wideband echo disturbances is introduced and the results are summarized. The E-Model, a planning tool for telecommunication networks, considers the degradation of the speech quality c...

This paper presents evaluations of a nonlinear-echo suppressor based on a frequency-domain model of highly nonlinear residual echo. The residual-echo model, which is based on correlation between spectral amplitudes of residual echo and echo replica, is evaluated by a regression analysis. The results justify the nonlinear-echo suppressor structure. The output signals are subjectively evaluated b...

Acoustic echo arises due to acoustic coupling between the loudspeaker and the microphone of a communication device. Acoustic echo cancellation and suppression techniques are used to reduce the acoustic echo. In this work we propose to first cancel the early echo, which is related to the early part of the echo path, and subsequently suppress the late echo, which is related to the later part of t...

PURPOSE To compare lesion enhancement after injection of gadopentetate dimeglumine on spin-echo and gradient-echo T1-weighted images. METHODS A total of 48 contrast-enhancing intracranial lesions were evaluated using a spin-echo and two gradient-echo T1-weighted pulse sequences. Percent contrast, contrast-to-noise, and signal-to-noise measurements were made on the spin-echo T1-weighted, three...

Acoustic echoes arise whenever there is acoustic coupling between a loudspeaker and a microphone. A traditional solution for eliminating the undesired echo signal is an acoustic echo canceler (AEC), which identifies the echo path between a loudspeaker and a microphone by means of an adaptive filter. The echo signal can be canceled successfully when the modeling filter approaches the true echo p...

شرایط افروزش و اشتعال سوخت‌های گداخت هسته‌ای در حضور ناخالص­‌ها، یکی از موارد مهمی است که طراحی قرص‌های سوخت باید مورد توجه قرار گیرد. این مقاله اثر ناخالصی هسته سنگین طلا بر کلیه فرایندهای احتراق پلاسمای غیرتعادلی دوتریم- تریتیم مدل چهار دمایی آن شکل تابع توزیع انرژی رفتار فوتون‌ها تأثیر می‌گذارد بررسی گرفته است. مطالعه شامل اثرات منفی سوخت، طول زمان تشکیل لکه داغ نتایج محاسبات عددی به­ دست آم...

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