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971.
Petru Blaga Teodora C?tina? Gheorghe Coman 《Applied mathematics and computation》2011,218(7):3072-3082
We construct and analyze Bernstein-type operators on triangles with curved sides, their product and Boolean sum. We study the interpolation properties and approximation accuracy. Using the modulus of continuity we also study the remainders of the corresponding approximation formulas. Finally, there are given some particular cases and numerical examples. 相似文献
972.
Hao Jiang Roberto Barrio Housen LiXiangke Liao Lizhi Cheng Fang Su 《Applied mathematics and computation》2011,217(23):9702-9716
This paper presents a compensated algorithm to accurately evaluate a polynomial expressed in Chebyshev basis of the first and second kind with floating-point coefficients. The principle is to apply error-free transformations to improve the traditional Clenshaw algorithm. The new algorithm is as accurate as the Clenshaw algorithm performed in twice the working precision. Forward error analysis and numerical experiments illustrate the accuracy and properties of the proposed algorithm. 相似文献
973.
This paper presents a diffusion model to explain the competitive diffusion of the repurchased products in knowledgeable manufacturing. The acute market competition accelerates the products’ improvement, which requires that the manufacturing enterprises be highly capable of rapid reaction by means of knowledgeable manufacturing. To forecast the diffusion behavior effectively enables the realization of knowledgeable manufacturing system (KMS) which targets T (time), Q (quality), C (cost), S (service), and E (environment). Various diffusion models have emerged since Bass model was firstly proposed in 1969. A nonlinear model of the repurchased competitive products is proposed on the basis of the product diffusion analysis. By taking the frequently purchased products as example, the stability of the model is examined in light of the qualitative theory of differential equations and proved by the approximate linearization method. As the qualitative analysis reveals, between the two frequently purchased products competing in the same market, one undoubtedly occupies a fixed market share while the other may finally be eliminated from the market. A special case of the problem is that both products are one-time-purchased. With the corresponding model given, the qualitative analysis shows that either of the products occupies a market share, the size of which is determined by the product’s competitive strength and the new product’s time-to-market. A system dynamics model is then established and simulated by vensim. The result is consistent with that of the qualitative analysis. 相似文献
974.
考虑载流子陷获效应建立了碲锌镉(CdZnTe)像素阵列探测器感应电荷分布模型,并从非平衡载流子连续方程出发,推导了晶体内部陷获载流子数密度分布,得到了CdZnTe探测器成像调制传递函数评价模型。数值计算结果表明:随入射光子能量的增加,探测器成像质量明显下降;当电子载流子与空穴载流子迁移寿命积范围分别为0.510-3 to 5.010-3 cm2/V,2.010-5 to 7.510-5 cm2/V时,电子载流子感应信号是探测器响应信号的主要来源,而空穴迁移寿命积变化对探测器成像性能的影响有限,所建立模型的载流子收集特性与实际探测器载流子收集特性相符。搭建了40 mm40 mm的CdZnTe成像探测系统,探测并获得了系统预采样调制传递函数。实验结果表明:模型理论值与实验数据相符合,实际CdZnTe晶体中存在的固有深能级缺陷、实验所采用的非单色性X射线源及较大的实际像素间隙是造成理论值与实验结果存在一定偏差的主要原因。 相似文献
975.
976.
为进一步提高图像法自动聚焦的性能,提出了一种差分式提取图像边缘的方法,并构造了图像清晰度的小波评价函数,同时利用微粒群(PSO)算法对聚焦区域进行快速搜索。首先,介绍了差分式边缘提取方法及其优势,给出了一种评价区域的选取判据以及基于PSO的高效搜索方法;然后,对小波评价函数参数进行了比较分析和优选;最后,与传统方法进行了对比实验。结果表明,由于采用了差分式提取方法以及新的自适应聚焦窗口和评价函数,聚焦曲线较传统方法具有更高的调焦分辨率,PSO算法的使用使聚焦速度提高了约170 ms,聚焦精度约为2.3μm,同时调焦效果不受初始位置的影响。 相似文献
977.
Guo Qiang Hu Li Li Hou Yong Yang Lei Yi Song Qiang Xie Guo Qiang Wang Nan Nan Duan Tie Yao Chao Xiao Yi Wen Wen Long Huang 《中国化学快报》2011,22(7):804-806
To further expand an effective modified route for the shift from an antibacterial fluoroquinolone(FQ) to an antitumor FQ,two series of title compounds based on an isostere of the FQ C3 carboxylic group with two fused heterocyclic rings,[1,2,4]triazolo[3,4- b][1,3,4]thiadiazine and pyrazolo[5,1-c][1,2,4]triazole,respectively,were designed and synthesized starting from the current antibacterial FQs,and their in vitro antitumor activity against L1210,CHO cell lines were evaluated via their respective IC50 values. 相似文献
978.
克拉玛依市维吾尔族居民膳食调查 总被引:1,自引:0,他引:1
为了解新疆克拉玛依市维吾尔族居民膳食营养状况,采用食物频率法对该地区401名维吾尔族居民进行膳食调查和营养评价.结果表明,克拉玛依市维吾尔族居民膳食种类比较单一,导致能量、碳水化合物、硫胺素、核黄素、钙等营养素未达到RNI的要求,而脂肪、胆固醇、盐摄入量偏高.提示硫胺素、核黄素、钙、镁为当地维吾尔族缺乏的营养素,建议对... 相似文献
979.
980.