效应面优化模型获取Y_(4)GeO_(8)∶Bi^(3+),Eu^(3+)红色荧光粉掺杂浓度

使用更直接的方法(效应面优化模型)预测了Y_(4)GeO_(8)∶Bi^(3+),Eu^(3+)样品的最强红光发射。预测最佳样品掺杂的Bi^(3+)离子和Eu^(3+)离子浓度分别为31.03%和67.36%(摩尔分数)。制备最佳样品后对其光致发光性能进行了测试和表征。荧光粉Y_(4)GeO_(8)∶31.03%Bi^(3+),67.36%Eu^(3+)具有最强的红光发射,并且强度的实验值和理论值之间的差值很小。优化样品的色坐标为(0.6457,0.3490),计算出的色纯度为98%,内量子效率高达72.5%。本文提供了一种直接寻找发光最强的荧光粉最佳掺杂浓度的方法,可用于探索各种类型的共掺杂荧光粉。

应用数据挖掘技术构建无机钙磷制剂相容性效应面预测模型

目的:为安全合理使用无机钙、磷制剂组方肠外营养液,有效评判肠外营养处方中是否存在产生钙磷沉淀的风险,提供实验室数据及预测计算模型支持。方法:应用自研动态法微粒监测装置对无机钙、磷浓度、温度、pH值、复方氨基酸种类及浓度、葡萄糖浓度7个影响因素全部水平相互组合实验,并运用R软件建立逻辑回归、随机森林算法和支持向量机3种肠外营养液中无机钙磷制剂相容性效应面预测模型,对比评价3种算法,优选模型并验证拟合度。结果:(1)实验共获取14 400组有效数据集。(2)通过对3种模型的评价对比,随机森林算法构建的肠外营养液中无机钙磷制剂相容性效应面模型准确率最高、预测效果最好。(3)基于随机森林算法的模型分析显示钙浓度、磷浓度、pH值、温度、葡萄糖浓度与无机钙磷沉淀的产生呈正相关,其中钙浓度对沉淀的产生影响最大,2类复方氨基酸的浓度与无机钙磷沉淀的产生呈负相关。(4)基于随机森林算法构建的效应面模型进行实验分析验证,预测结果与实验结果拟合度高。结论:该研究应用现代分析技术研发了可动态监测无机钙磷制剂配伍后沉淀产生的装置,并构建了肠外营养液中无机钙磷制剂相容性效应面模型。应用该模型,输入相应参数,便可预测出该配方组合是否会有无机钙磷沉淀产生,为临床医务人员安全合理开具肠外营养处方提供实验室依据及计算模型支持。

An Econometric Analysis on the Effect of Climate Change on Wheat Cropping Area in China

[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.

A New Poly-Si TFTs DC Model for Device Characterization and Circuit Simulation

A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.

Electronic Transport and Magnetic Properties in Ferroelectric- Ferromagnetic Composites La5/8Ca3/8MnO3：ErMnO3

The crystal structures and electronic transport properties of composites, xLa5/8Ca3/8MnO3 （1-x）ErMnO3 （x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1）, where ErMnO3 is the insulating ferroelectric and La5/8Ca3/8MnO3 is the metallic ferromagnetic component, were studied. The magnetization of samples （x=0, 0.5, 1） were also measured as a function of temperature from 4 K to 300 K. The X-ray diffraction data show La5/8Ca3/8MnO3 and ErMnO3 are almost complete immiscible, originating from the significant difference in their crystal structures. All the composites show a metal-insulator transition when the molar fraction of xLa5/8Ca3/8MnO3 component x≥0.4 and the electronic transport behaviors follow the classical percolation theory model very well. Magnetization of the mixture with x=0.5 is unique and enhanced greatly compared with that of pure ErMnO3. Comprehensive analysis of the electronic transport and magnetic results suggests that this material system is a new kind of multiferroic with stronger magnetism in a wider temperature range compared with the single phase multiferroic ErMnO3.

Numerical Simulation of Seaplane Wave Ground Effect with Crosswind

Under the absolute coordinate system, the unsteady Reynolds averaged Navier-Stokes(URANS)equations and the k-ω SST turbulence model are solved using the finite volume method to simulate the aerodynamic characteristics of large seaplane flying with the ground-effect above wavy surface. The velocity inlet wave-making method and the volume of fluid model are used to accurately simulate the linear regular waves and to precisely capture the free surface. This paper studies the influence of the sideslip angle on the aerodynamic characteristics of large seaplane when it is cruising above wavy water. The results show that the wave surface mainly affects the pressure distribution on the lower surface of the wing. When the sideslip angle varies from 0° to 8°,the varying of frequency of aerodynamic forces is consistent with the wave encounter frequency,and both periods are 0.6 s. With the increase of the sideslip angle,the lift coefficient and the pitching moment coefficient decrease. However,when the sideslip angle is smaller than 4°,the decrease amplitude is small,and the significant decrease occurs above 4° and during the whole process of the change of sideslip angle,the aerodynamic fluctuation amplitude is almost unchanged. As the drag coefficient increases with the increase of sideslip angle,significant increase also occurs when the value is greater than4°,and the fluctuation amplitude does not show any correlations. The rolling moment coefficient and yaw moment coefficient increase with the increase of the sideslip angle,and the fluctuation amplitudes of both increase linearly with the increase of the sideslip angle.

A Panel Data Analysis of Corporate Attributes and Stock Prices for Indian Manufacturing Sector

Stock prices have always been considered as unpredictable phenomena due to their dynamic patterns. Identifying the forces that contribute to variations of stock prices is probably one of the most researched areas in finance. This study relates stock prices to the stock volatility （measured by beta） and to corporate attributes, i.e., size, liquidity, profits, leverage, and returns. The study is based on manufacturing sector in India, and it is based on a sample of 3,027 manufacturing companies during the periods from 1991-1992 to 2006-2007 collected from the Centre for Monitoring Indian Economy （CMIE） database. The regressions were performed with the dummies for time effect and firm effect separately and then for both effects together. Panel data models have been used to estimate the stock prices equation. The model finds out fixed and random effects between independent and explanatory variables and analyzes them through Hausman test. The paper also studies multicollineairity that may exist amongst the selected variables. The study shows that volatility （represented by Beta）, profit （represented by earnings per share （EPS））, and size （represented by market capitalization （MCAP）） significantly influence the stock prices （at the level of 5%）. Panel data analysis using Hausman test supports the fixed effect model.

Simulation of droplet topography on superhydrophobic surface

We established a novel droplet model (with-gravity model) to show the gravity effect of the droplet in the contact angle experiment.By using with-gravity model, we obtained a three-dimensional topography of the droplet including the height of the droplet, the shape of the baseline and the circumference of the baseline.Comparing the with-gravity model with the ideal spherical model, our model considered the measurement error caused by gravity effect in the contact angle experiment which is a key point to influence the three-dimension topography of the droplet.From the calculation of our model, we found that there were two important points to enhance the measurement error: the size of the droplet and the contact angle.With the droplet and the contact angle became larger, measurement error was obviously increased.

Respiratory face mask:a novel and cost-effective device for use during the application of myocardial ischemia in rats

To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction,we use a novel device comprised of a face mask and a head/neck retainer in this study.We report the basic design of the novel respiratory face mask(RFM) and evaluate its performance in a rat model of myocardial ischemia.The device is cost-effective and easier to handle than other devices,such as tracheal intubation.Compared with conventional tracheal intubation,we found that RFM shortens operation time significantly while keeping blood indices normal;the mean operation time for rats in the mask group was(32±3) min,and that for the intubation group was(45±7) min(P<0.05).Moreover,the size and shape of the RFM can be changed according to the body weight of rats.In conclusion,RFM is an appropriate device for the establishment of myocardial infarction or ischemia-reperfusion in rats.