نتایج جستجو برای: diffusion volume
تعداد نتایج: 469130 فیلتر نتایج به سال:
The diffusion tensor is currently the accepted model of diffusion in biological tissues. The measured diffusion behavior may be more complex when two or more distinct tissues with different diffusion tensors occupy the same voxel. In this study, a partial volume model of MRI signal behavior for two diffusion-tensor compartments is presented. Simulations using this model demonstrate that the con...
BACKGROUND AND PURPOSE Brain volume and diffusion change during maturation. Quantitation of these changes may be helpful in understanding normal brain development. We used diffusion-weighted imaging to characterize the volumetric and diffusion changes in vivo. METHODS We recruited 30 pediatric volunteers (aged 1 month-17 years; 14 male, 16 female). Diffusion was measured in three orthogonal d...
A study of the microstructure of polymers is essential for the understanding of their anomalous diffusion properties. The concept of free volume may be utilized to study relaxation phenomena and diffusion processes in polymers. Since a quantitative definition of free volume is not possible, a new concept called available volume is introduced. A simple geometric definition of available volume, r...
اکسید منیزیم با خلوص بالای 95% دارای کاربرد نسوز در صنایع مختلف می باشد. بالا بودن خلوص اکسید منیزیم، باعث افزایش مقاومت مکانیکی و شیمیایی آن در شرایط مختلف عملیاتی می شود. در فرآیند تولید اکسید منیزیم، یک فرآیند کلسیناسیون وجود دارد. در این مطالعه فرآیند کلسیناسیون را در یک کوره عمودی نرمال بررسی شد. کوره عمودی مهمترین قسمت فرآیند تولید اکسید منیزیم می باشد، چراکه با تامین انرژی لازم برای تبدی...
PURPOSE To investigate additional information provided by maps of relative cerebral blood flow in functional magnetic resonance (MR) imaging of human hyperacute cerebral ischemic stroke. MATERIALS AND METHODS Diffusion-weighted and hemodynamic MR imaging were performed in 23 patients less than 12 hours after the onset of symptoms. Maps of relative cerebral blood flow and tracer mean tissue tr...
The present article deals with the study of propagation of plane waves in isotropic generalized thermoelastic diffusion with voids under initial stress. It is found that, for two dimensional model of isotropic generalized thermoelastic diffusion with voids under initial stress, there exists four coupled waves namely, P wave, Mass Diffusion (MD) wave, thermal (T) wave and Volume Fraction (VF) wa...
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