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Alan F. Karr 《Journal of multivariate analysis》1985,16(3):368-392
Given i.i.d. point processes N1, N2,…, let the observations be p-thinnings N′1, N′2,…, where p is a function from the underlying space E (a compact metric space) to [0, 1], whose interpretation is that a point of Ni at x is retained with probability p(x) and deleted with probability 1−p(x). Strongly consistent estimators of the thinning function p and the Laplace functional LN(f) = E[e−N(f)] of the Ni are constructed; associated “central limit” properties are given. Tests are presented, for the case when the Ni and N′i are both observable, of the hypothesis that the N′i are p-thinnings of the Ni. State estimation techniques are developed for the case where the Ni are Cox processes directed by unobservable random measures Mi; these techniques yield minimum mean-squared error estimators, based on observation of only the thinned processes N′i of the Ni and the directing measures Mi. Limit theorems for empirical Laplace functionals of point processes are given. 相似文献
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We establish local asymptotic normality of thinned empirical point processes, based on n i.i.d. random elements, if the probability
of thinning satisfies
. It turns out that the central sequence is determined by the limit of the coefficient of variation of the tangent function. The central sequence depends only on the total number
of nonthinned observations if and only if this limit is 1 or –1. In this case under suitable regularity conditions, an asymptotically efficient estimator of the underlying parameter can be based on
only. An application to density estimation leads to a fuzzy set density estimator, which is efficient in a parametric model. In a nonparametric setup, it can also outperform the usual kernel density estimator, depending on the values of the density and its second derivative. 相似文献
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衬底温度保持恒定, 在Se气氛下按照一定的元素配比顺序蒸发Ga, In, Cu制备厚度约为0.7 μrm的Cu(In0.7Ga0.3)Se2 (CIGS)薄膜. 利用X射线衍射仪分析薄膜的晶体结构及物相组成, 扫描电子显微镜表征薄膜形貌及结晶质量, 二次离子质谱仪测试薄膜内部元素分布, 拉曼散射谱 分析薄膜表面构成, 带积分球附件的分光光度计测量薄膜光学性能. 研究发现在Ga-In-Se预制层内, In主要通过晶界扩散引起Ga/(Ga+In)分布均匀化. 衬底温度高于450 ℃时, 薄膜呈现单一的Cu(In0.7Ga0.3)Se2相; 低于400℃, 薄膜存在严重的Ga的两相分离现象, 且高含Ga相主要存在于薄膜的上下表面; 低于300 ℃, 薄膜结晶质量进一步恶化. 薄膜表层的高含Ga相Cu(In0.5Ga0.5)Se2以小晶粒形式均匀分布于薄膜表面, 增加了薄膜的粗糙度, 在电池内形成陷光结构, 提高了超薄电池对光的吸收. 加上带隙值较小的低含Ga相的存在, 使电池短路电流密度得到较大改善. 衬底温度在550 ℃–350 ℃变化时, 短路电流密度JSC是影响超薄电池转换效率的主要因素; 而衬底温度Tsub低于300 ℃时, 开路电压VOC和填充因子FF降低已成为电池性能减退的主要原因. Tsub为350 ℃时制备的0.7 μm左右的超薄CIGS电池转换效率达到了10.3%.
关键词:
2薄膜')" href="#">Cu(In,Ga)Se2薄膜
衬底温度
超薄
太阳电池 相似文献
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Koichiro Sakaguchi Shunsuke Furukawa Satoshi Matsuo Naotaka Sakashita Takushige Katsura Kyoko Yamazaki Hideo Kawaguchi Atsushi Maki Eiji Okada 《Optical Review》2009,16(2):74-80
The simplified cranial window, which is transparent thinned skull, has been used for the optical imaging of cortical tissue
of small animals to measure the concentration change in haemoglobin as an intrinsic signal of brain activation. The multi-spectral
images of the cortical tissue of guinea pigs through the skull cranial window were compared with those of the exposed cortex
to evaluate the influence of the scattering and absorption properties of the skull on the measurement of the concentration
change in haemoglobin. Although skull thickness affects the sensitivity of the optical signal due to a decrease in mean optical
path length in the cortical tissue, the influence of the skull cranial window on the wavelength dependence of optical path
length can be ignored when the skull thickness is less than approximately 100 mm. Accurate concentration changes in oxygenated
and deoxygenated haemoglobins can be calculated from the optical signal measured through a skull cranial window and the wavelength
dependence of optical path length for the exposed cortex. 相似文献
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