用仿射对应求4点椭圆的方法及应用

本文是应用仿射对应原理,以椭圆曲线上4个点及其中心,求作椭圆的方法。以及用此方法解决某些一般形式的二次曲面中的一些几何作图问题。     

Academic trajectories of newcomer immigrant youth.

Immigration to the United States presents both challenges and opportunities that affect students' academic achievement. Using a 5-year longitudinal, mixed-methods approach, we identified varying academic trajectories of newcomer immigrant students from Central America, China, the Dominican Republic, Haiti, and Mexico. Latent class growth curve analysis revealed that although some newcomer students performed at high or improving levels over time, others showed diminishing performance. Multinomial logistic regressions identified significant group differences in academic trajectories, particularly between the high-achieving youth and the other groups. In keeping with ecological–developmental and stage–environment fit theories, School Characteristics (school segregation rate, school poverty rate, and student perceptions of school violence), Family Characteristics (maternal education, parental employment, and household structure), and Individual Characteristics (academic English proficiency, academic engagement, psychological symptoms, gender, and 2 age-related risk factors, number of school transitions and being overaged for grade placement) were associated with different trajectories of academic performance. A series of case studies triangulate many of the quantitative findings as well as illuminate patterns that were not detected in the quantitative data. Thus, the mixed-methods approach sheds light on the cumulative developmental challenges that immigrant students face as they adjust to their new educational settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

The distribution of neutrons produced by the reaction of 50MeV/u ^12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.     

微电网技术研究现状

首先阐释了微网的概念、结构及特点,然后对当前美国、欧盟和日本等国的微网研究现状进行了介绍,并介绍了微网运行方式,最后着重探讨了现阶段微电网研究中的关健问题和相关研究现状。     

基于多幅图像的有效点扩散函数的高精度测量

将图像融合以及高精度测量方法应用于天文图像处理,对图片进行处理得到有效点扩散函数,并将有效点扩散函数拟合星像,得到星体的位置与光度信息．结果表明, 方向平均定位精度为0．036 pixel,Y方向平均定位精度为0．O44 pixel,平均测光精度达到0．032 magnitude,测量结果验证了该算法的有效性．     

α—Fe2O3气敏元件的可靠性环境试验

探讨了α－Ｆｅ２Ｏ３半导体气敏元件的可靠性环境试验方法，对该元件的可靠性环境试验结果进行了数据处理和统计分析；探讨了该元件的主要失效模式，运用不同的评定方法对元件的环境应力适应能力进行了定量估计。     

Invariant Deformation Element Model Interpretation to the Crystallography of Diffusional Body-Centered-Cube to Face-Centered-Cube Phase Transformations

The crystallography of body-centered-cube to face-centered cube (bcc-to-fcc) diffusion phase transformations in a duplex stainless steel and a Cu-Zn alloy, including long axis, orientation relationship (OR), habit plane (HP), and dislocation spacing, is successfully interpreted with one-step rotation from the Bain lattice relationship by applying a simplified invariant line (IL) analysis. It is proposed that the dislocation slipping direction in the matrix plays an important role in controlling the crystallography of precipitation.     

Thermodynamic Study on the Rare Earth Vapour Complex PrAl_3Cl_(12)

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数字图像超分辨率重建技术综述

图像超分辨率重建的目的是通过一幅或多幅低分辨率降质图像来估计一幅视觉效果较好的高分辨率图像.它从传统的图像恢复与重建技术而来,利用图像之间的信息互补来获得比单幅图像更多的细节.超分辨率技术主要分为两大类:基于重建的超分辨率技术和基于学习的超分辨率技术.基于重建的超分辨率技术按照特定的退化模型,通过输入的图像来估计高分辨率图像.基于学习的超分辨率技术从训练样本中获取先验知识,对输入图像的信息进行补充,可以获得比基于重建的算法更好的效果.对超分辨技术的算法作了系统的介绍,并指出图像的配准、退化模型的建立、盲估计问题、学习模型的建立、学习算法等仍是图像超分辨率技术中存在的主要问题,也是进一步研究的方向.