A flow past a circular-section cylinder with a perforated conic shroud, in which the perforation is located at the peak of the conic disturbance as the shroud installed on the cylinder and uniformly distributed with s...A flow past a circular-section cylinder with a perforated conic shroud, in which the perforation is located at the peak of the conic disturbance as the shroud installed on the cylinder and uniformly distributed with several circular holes, is numerically simulated at a Reynolds number of 100. Two factors in the perforation are taken into account, i.e. the attack angle relative to the direction of incoming flow and diameter of holes. The effect of such perforation on the drag, lift and vortex-shedding frequency is mainly investigated. Results have shown that variation of the attack angle has a little effect, especially on the drag and vortex-shedding frequency, except in certain cases due to the varied vortex-shedding patterns in the near wake. The increasing hole diameter still exhibits a little effect on the drag and frequency of vortex shedding, but really reduces the lift, in particular at larger wavelength, such as the lift reduction reaching almost 66% 68% after introducing the perforation.展开更多
【目的】基于酶联免疫吸附测定法(ELISA)检测原理,建立高灵敏度的直接竞争法检测木薯粉及其制品中的黄曲霉毒素B_(1)(AFB_(1)),为木薯食品安全提供技术支持。【方法】通过对AFB1抗原结构改造、免疫和细胞融合等过程获得抗原抗体,建立高...【目的】基于酶联免疫吸附测定法(ELISA)检测原理,建立高灵敏度的直接竞争法检测木薯粉及其制品中的黄曲霉毒素B_(1)(AFB_(1)),为木薯食品安全提供技术支持。【方法】通过对AFB1抗原结构改造、免疫和细胞融合等过程获得抗原抗体,建立高灵敏度检测方法,并进行木薯粉及其制品样本的实例验证。【结果】制备的AFB1抗原和抗体,其抗体亚型均为IgG_(1),灵敏度最高的3F2细胞株产生的抗体对黄曲霉毒素G_(1)、G_(2)和B2交叉反应率分别为21.4%、1.9%和8.8%,且对其他毒素类无交叉反应,建立的ELISA线性区间为0.02~0.48μg/kg,半数抑制浓度(IC_(50))为0.047μg/kg,标准方程为y=-3.074x-4.3066(R2=0.9978)。以35%甲醇水溶液作为标准品稀释液,木薯食品原料用70%甲醇水溶液加0.2 g NaCl作为提取液,含油脂的木薯糕点用70%甲醇水溶液作为提取液,所有样本均为10倍稀释,检测限0.2~4.8μg/kg,样品添加回收率81.5%~120.0%,变异系数均小于8.5%。应用验证试验表明,自建ELISA试剂盒对96份样本检出19份阳性样本,购买试剂盒检出7份阳性,大于2.0μg/kg的样本检测结果完全符合,自建ELISA试剂盒方法灵敏度优于购买的ELISA试剂盒。【结论】本研究建立的直接竞争ELISA方法灵敏度高,操作简单,可广泛应用于木薯粉及其制品样本中AFB1的快速测定。展开更多
为探究锂电池极片涂布工艺参数与浆料涂层湿厚度之间的定量关系,基于Volume of Fluid(VOF)方法建立了狭缝挤压式涂布外流场的数值计算模型,分析了锂电池浆料微观流动过程及涂布缺陷形成原因,运用Minitab软件设计了三因子两水平的全因子...为探究锂电池极片涂布工艺参数与浆料涂层湿厚度之间的定量关系,基于Volume of Fluid(VOF)方法建立了狭缝挤压式涂布外流场的数值计算模型,分析了锂电池浆料微观流动过程及涂布缺陷形成原因,运用Minitab软件设计了三因子两水平的全因子仿真试验,讨论了基材运动速度、涂布间隙和入口流速对浆料涂层湿厚度的影响规律。仿真结果表明,在一定工艺参数范围内可获得稳定均匀的涂层,否则会产生涂布缺陷,其中基材运动速度和入口流速为涂层湿厚度主要影响因素,建立的数学模型在仿真试验条件下可预测湿涂层的厚度,为锂电池极片涂布工艺参数的优化提供理论支持。展开更多
A Nonlinear Fluid Damping （NFD） in the form of the square-velocity is applied in the response analysis of Vortex-Induced Vibrations （VIV）. Its nonlinear hydrodynamic effects on the coupled wake and structure oscil...A Nonlinear Fluid Damping （NFD） in the form of the square-velocity is applied in the response analysis of Vortex-Induced Vibrations （VIV）. Its nonlinear hydrodynamic effects on the coupled wake and structure oscillators are investigated. A comparison between the coupled systems with the linear and nonlinear fluid dampings and experiments shows that the NFD model can well describe response characteristics, such as the amplification of body displacement at lock-in and frequency lock-in, both at high and low mass ratios. Particularly, the predicted peak amplitude of the body in the Griffin plot is in good agreement with experimental data and empirical equation, indicating the significant effect of the NFD on the structure motion.展开更多
基金supported by the National Key Scientific Instrument and Equipment Development Program of China(Grant No.2011YQ120048)
文摘A flow past a circular-section cylinder with a perforated conic shroud, in which the perforation is located at the peak of the conic disturbance as the shroud installed on the cylinder and uniformly distributed with several circular holes, is numerically simulated at a Reynolds number of 100. Two factors in the perforation are taken into account, i.e. the attack angle relative to the direction of incoming flow and diameter of holes. The effect of such perforation on the drag, lift and vortex-shedding frequency is mainly investigated. Results have shown that variation of the attack angle has a little effect, especially on the drag and vortex-shedding frequency, except in certain cases due to the varied vortex-shedding patterns in the near wake. The increasing hole diameter still exhibits a little effect on the drag and frequency of vortex shedding, but really reduces the lift, in particular at larger wavelength, such as the lift reduction reaching almost 66% 68% after introducing the perforation.
文摘【目的】基于酶联免疫吸附测定法(ELISA)检测原理,建立高灵敏度的直接竞争法检测木薯粉及其制品中的黄曲霉毒素B_(1)(AFB_(1)),为木薯食品安全提供技术支持。【方法】通过对AFB1抗原结构改造、免疫和细胞融合等过程获得抗原抗体,建立高灵敏度检测方法,并进行木薯粉及其制品样本的实例验证。【结果】制备的AFB1抗原和抗体,其抗体亚型均为IgG_(1),灵敏度最高的3F2细胞株产生的抗体对黄曲霉毒素G_(1)、G_(2)和B2交叉反应率分别为21.4%、1.9%和8.8%,且对其他毒素类无交叉反应,建立的ELISA线性区间为0.02~0.48μg/kg,半数抑制浓度(IC_(50))为0.047μg/kg,标准方程为y=-3.074x-4.3066(R2=0.9978)。以35%甲醇水溶液作为标准品稀释液,木薯食品原料用70%甲醇水溶液加0.2 g NaCl作为提取液,含油脂的木薯糕点用70%甲醇水溶液作为提取液,所有样本均为10倍稀释,检测限0.2~4.8μg/kg,样品添加回收率81.5%~120.0%,变异系数均小于8.5%。应用验证试验表明,自建ELISA试剂盒对96份样本检出19份阳性样本,购买试剂盒检出7份阳性,大于2.0μg/kg的样本检测结果完全符合,自建ELISA试剂盒方法灵敏度优于购买的ELISA试剂盒。【结论】本研究建立的直接竞争ELISA方法灵敏度高,操作简单,可广泛应用于木薯粉及其制品样本中AFB1的快速测定。
文摘为探究锂电池极片涂布工艺参数与浆料涂层湿厚度之间的定量关系,基于Volume of Fluid(VOF)方法建立了狭缝挤压式涂布外流场的数值计算模型,分析了锂电池浆料微观流动过程及涂布缺陷形成原因,运用Minitab软件设计了三因子两水平的全因子仿真试验,讨论了基材运动速度、涂布间隙和入口流速对浆料涂层湿厚度的影响规律。仿真结果表明,在一定工艺参数范围内可获得稳定均匀的涂层,否则会产生涂布缺陷,其中基材运动速度和入口流速为涂层湿厚度主要影响因素,建立的数学模型在仿真试验条件下可预测湿涂层的厚度,为锂电池极片涂布工艺参数的优化提供理论支持。
基金Project supported by the National High Techology Research and Development Program of China (863 Program, Grant No2006AA09Z350)the Chinese Academy of Sciences (Grant No KJCX2-YW-L02)
文摘A Nonlinear Fluid Damping （NFD） in the form of the square-velocity is applied in the response analysis of Vortex-Induced Vibrations （VIV）. Its nonlinear hydrodynamic effects on the coupled wake and structure oscillators are investigated. A comparison between the coupled systems with the linear and nonlinear fluid dampings and experiments shows that the NFD model can well describe response characteristics, such as the amplification of body displacement at lock-in and frequency lock-in, both at high and low mass ratios. Particularly, the predicted peak amplitude of the body in the Griffin plot is in good agreement with experimental data and empirical equation, indicating the significant effect of the NFD on the structure motion.
