Numerical Simulation and Evaluation of a Four-Channel-by-Four-Channel Double-Nuclear RF Coil for 1H MRI and 31P MRSI at 7 T

2018 ◽  
Vol 54 (11) ◽  
pp. 1-5 ◽  
Author(s):  
Feng Du ◽  
Shengping Liu ◽  
Qiaoyan Chen ◽  
Nan Li ◽  
Yan Dou ◽  
...  
2011 ◽  
Vol 301-303 ◽  
pp. 452-455 ◽  
Author(s):  
Yuji Kotani ◽  
Hisaki Watari ◽  
Akihiro Watanabe

The approach to total weight reduction has been a key issue for car manufacturers as they cope with more and more stringent requirements for fuel economy. In sheet metal forming, local increases in product-sheet thickness effectively contribute to reducing the total product weight. Products could be designed more efficiently if a designer could predict and control the thickness distribution of formed products. This paper describes a numerical simulation and evaluation of the material flow in local thickness increments of products formed by an ironing process. In order to clarify the mechanism of the local increase in sheet thickness, a 3-D numerical simulation of deep drawing and ironing was performed using finite-element simulation. The effects of various types of finite elements that primarily affect thickness changes in original materials and thickness prediction were investigated. It was found that the sheet-thickness distribution could be predicted if the original material was relatively thick and if an appropriate type of finite element is selected.


Author(s):  
Gang Zheng ◽  
Fangwei Xie ◽  
Xialong Li ◽  
Jian Liu ◽  
Jianzhong Cui ◽  
...  

2013 ◽  
Vol 52 (33) ◽  
pp. 11712-11722 ◽  
Author(s):  
Ahad Sarraf Shirazi ◽  
Shayan Karimipour ◽  
Rajender Gupta

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Andreas Lucius ◽  
Gunther Brenner

Flow instabilities like rotating stall can lead to severe vibrations in turbomachines if the eigenfrequency of the rotor is equal to the stall frequency. The goal of the present work is to shed some light on the origin of the rotating stall phenomenon in a centrifugal pump. The resulting fluctuating loads are quantified using numerical computations. For the chosen configuration transient PIV data are available for validation. In addition to measuring the stall frequency in the stationary frame, the CFD data is analyzed in the rotating frame. A Fourier analysis is done for a large number of sample points. This enables us to determine the local variation of amplitudes for a given frequency. Together with eigenfrequencies and eigenmodes of the rotor determined from modal analysis, it is possible to evaluate the risk of resonance vibration excited from fluctuating fluid forces.


Author(s):  
Bu S. Park ◽  
Joshua W. Guag ◽  
Leonardo M. Angelone ◽  
Sunder S. Rajan

We present experimental and numerical simulation results showing that high dielectric materials (HDMs) located outside of a RF head coil decrease the electric field (E-field, |E|) with minimum change of the RF magnetic field (B1+) at 3T MRI imaging. Compared to previous research using HDMs located between the RF coil and sample, our method locating the HDM outside the coil allowed an increased sample size and more flexibility of HDM thickness optimization. Numerical simulation results showed more than 30% decrease in the local SAR at the boundary region of the head model. Validating experimental results showed a 21% decrease in the maximum |Etotal| using a HDM made of distilled water.


2013 ◽  
Vol 49 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Eun-Hee Lee ◽  
Erdenebayar Munkhtsetseg ◽  
Seung-Bum Kim ◽  
Jong-Chul Ha ◽  
Sang-Sam Lee ◽  
...  

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