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991.
Chan‐Yi Yang Chen‐Wei Wei Yen‐Ping Lin Hsiao‐Chien Tseng Ya‐Na Wu Chia‐Chun Chen Dar‐Bin Shieh Pai‐Chi Li 《中国化学会会志》2008,55(1):103-108
Gold nanoparticles with carbohydrate ligands attached on their surface have been synthesized and characterized with various techniques. The new nanoparticle conjugates have shown great potentials as a contrast agent for opto‐acoustic imaging. Hemocompatibility measurements of human blood for the carbohydrate‐gold nanoparticles have shown that the conjugates are feasible for in vivo testing. Preliminary quantitative flow measurements using the conjugates were also studied in this work based on the indicator‐dilution theory. In vitro phantom experiments were designed and conducted, and results were discussed. 相似文献
992.
In this paper, we consider the knot placement problem in B-spline curve approximation. A novel two-stage framework is proposed for addressing this problem. In the first step, the $l_{\infty, 1}$-norm model is introduced for the sparse selection of candidate knots from an initial knot vector. By this step, the knot number is determined. In the second step, knot positions are formulated into a nonlinear optimization problem and optimized by a global optimization algorithm — the differential evolution algorithm (DE). The candidate knots selected in the first step are served for initial values of the DE algorithm. Since the candidate knots provide a good guess of knot positions, the DE algorithm can quickly converge. One advantage of the proposed algorithm is that the knot number and knot positions are determined automatically. Compared with the current existing algorithms, the proposed algorithm finds approximations with smaller fitting error when the knot number is fixed in advance. Furthermore, the proposed algorithm is robust to noisy data and can handle with few data points. We illustrate with some examples and applications. 相似文献
993.
We investigate some integrable modified Heisenberg ferromagnet models by using the prolongation structure theory. Through associating them with the motion of curve in Minkowski space, the corresponding coupled integrable equations are presented. 相似文献
994.
995.
基于B样条迭代法的激光光条噪声去除技术研究 总被引:5,自引:0,他引:5
在基于线结构光的视觉测量系统中,激光光条中心的提取精度是影响系统最后精度的关键因素。目前常用的光条中心提取方法都没有去除光条上的干扰噪声,在分析现有方法的基础上提出了一种利用B样条迭代去除光条噪声的方法。以光条上的点作为控制顶点拟合B样条曲线,在同一位置下用B样条曲线上的点取代噪声点,这样反复修改噪声点的位置使其逐渐逼近实际曲线,从而达到去除噪声的目的。利用重心法提取去噪后光条的中心,着重分析了参与运算的像素的取值范围。通过对比实验证明该方法的提取精度远高于其它方法,从而验证了去除噪声的有效性。 相似文献
996.
997.
介绍声光效应的最新理论进展。采用光栅假设,对各向同性介质中的声光效应作了简要讨论,导出了第m级衍射光的衍射效率公式。研究和介绍一种新的声光效应实验装置。在实验中,应用线阵CCD光强分布测量仪等,通过改变超声波的频率和功率,分别实现了对激光束方向的控制和强度的调制;定量给出了声光偏转量的关系曲线和声光调制测量的关系曲线。实验表明,在布喇格衍射下,通过固定超声波功率,测量衍射光相对于零级衍射光的相对光强与超声波频率的关系曲线,不仅可以计算声速,还可以确定声光器件的带宽和中心频率。 相似文献
998.
We use the functional principal component analysis (FPCA) to model and predict the weight growth in children. In particular,
we examine how the approach can help discern growth patterns of underweight children relative to their normal counterparts,
and whether a commonly used transformation to normality plays any constructive roles in a predictive model based on the FPCA.
Our work supplements the conditional growth charts developed by Wei and He (2006) by constructing a predictive growth model
based on a small number of principal components scores on individual’s past.
This work was supported by National Natural Science Foundation of China (Grant No. 10828102), a Changjiang Visiting Professorship,
the Training Fund of Northeast Normal University’s Scientific Innovation Project (Grant No. NENU-STC07002) and the National
Institutes of Health Grant of USA (Grant No. R01GM080503-01A1). 相似文献
999.
The problem of determining the Bonnet hypersurfaces in R
n+1, for n > 1, is studied here. These hypersurfaces are by definition those that can be isometrically mapped to another hypersurface
or to itself (as locus) by at least one nontrivial isometry preserving the mean curvature. The other hypersurface and/or (the
locus of) itself is called Bonnet associate of the initial hypersurface.
The orthogonal net which is called A-net is special and very important for our study and it is described on a hypersurface. It is proved that, non-minimal hypersurface
in R
n+1 with no umbilical points is a Bonnet hypersurface if and only if it has an A-net. 相似文献
1000.
E. V. Sharoiko 《Mathematical Notes》2007,81(5-6):686-694
We obtain an effective criterion for the finiteness of the number of orbits contained in the closure of a given G-orbit for the case of a rational linear action of the group G: = (?*)k × SL 2(?) on a finite-dimensional linear space as well as on the projectivization of such a space. 相似文献