‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulato...‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration （FDA）, to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ＇stent versus stent＇ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents （the NIR and Multi-Link stents） are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi- Link stent design.展开更多
开发了结构性质关联模型(QSPR),实现了基于烃类化合物的结构特征预测黏温特性的功能。搜集了254种烃类化合物不同温度下的黏度数据,选择改进的Andrade方程来描述烃类化合物的黏温特性曲线,并通过对实验数据进行回归,获得了化合物的Andr...开发了结构性质关联模型(QSPR),实现了基于烃类化合物的结构特征预测黏温特性的功能。搜集了254种烃类化合物不同温度下的黏度数据,选择改进的Andrade方程来描述烃类化合物的黏温特性曲线,并通过对实验数据进行回归,获得了化合物的Andrade方程参数B和T_0。在此基础上,采用分子质量和15个基团作为分子的结构特征参数,建立神经网络模型预测Andrade模型参数B和T_0,平均相对误差分别为3.59%和1.27%。通过所预测的Andrade模型参数计算化合物的黏温性能,预测值与实验数据相比绝对平均误差为0.42 m Pa·s。展开更多
Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then an...Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.展开更多
文摘‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration （FDA）, to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ＇stent versus stent＇ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents （the NIR and Multi-Link stents） are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi- Link stent design.
文摘开发了结构性质关联模型(QSPR),实现了基于烃类化合物的结构特征预测黏温特性的功能。搜集了254种烃类化合物不同温度下的黏度数据,选择改进的Andrade方程来描述烃类化合物的黏温特性曲线,并通过对实验数据进行回归,获得了化合物的Andrade方程参数B和T_0。在此基础上,采用分子质量和15个基团作为分子的结构特征参数,建立神经网络模型预测Andrade模型参数B和T_0,平均相对误差分别为3.59%和1.27%。通过所预测的Andrade模型参数计算化合物的黏温性能,预测值与实验数据相比绝对平均误差为0.42 m Pa·s。
基金supported by the National Natural Science Foundation of China(Grant No.90207003).
文摘Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.
