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印度的钻石切磨业──对切磨师人数及其产品尺寸的评价
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作者 MenahemSevdermish A.R.Miciak +1 位作者 A.A.Levinson 闫晨 《宝石和宝石学杂志》 CAS 1999年第4期56-61,共6页
据公开文献报道,在90年代,印度钻石切磨师的人数估计在60万~80万为。根据印度每年成品钻的数量以及加工这些宝石的速度,我们估计印度约有40万个专职切磨师(主要在现代工厂里),每年一般可以抛磨大约7.5亿颗钻石。公开文献对切磨... 据公开文献报道,在90年代,印度钻石切磨师的人数估计在60万~80万为。根据印度每年成品钻的数量以及加工这些宝石的速度,我们估计印度约有40万个专职切磨师(主要在现代工厂里),每年一般可以抛磨大约7.5亿颗钻石。公开文献对切磨师人数的过高估计也许包括60万个家庭手工业中的兼职切磨师,其中有些平均每天只切磨一颗钻石;专职切磨师仅约20万人。以90年代中期印度抛磨钻石的总量(重量)和估计的平均尺寸(2.5pt或0.025ct)为基础,提出了一个假设的钻石产品尺寸。我们推测,占重量约80%和占总量96%的成品钻小于10pt(0.01ct)。印度的成品钻为3pt(0.03ct),约占重量的42%,占总量的65%(约5亿颗)。 展开更多
关键词 钻石切磨业 印度 切磨师 产品尺寸
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BLOCK COPOLYMER HOLLOW NANOSPHERES AND NANOTUBES
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作者 GuojunLiu 《Chinese Journal of Reactive Polymers》 2000年第f05期2-2,共1页
关键词 共聚物 纳米球 纳米管
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ASYMPTOTIC NORMALITY OF SOME ESTIMATORS IN A FIXED-DESIGN SEMIPARAMETRIC REGRESSION MODEL WITH LINEAR TIME SERIES ERRORS 被引量:10
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作者 JinhongYOU CHENMin GemaiCHEN 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2004年第4期511-522,共12页
Consider a semiparametric regression model with linear time series errors Y_k= x′ _kβ + g(t_k) + ε_k, 1 ≤ k ≤ n, where Y_k's are responses, x_k =(x_(k1),x_(k2),···,x_(kp))′ and t_k ∈ T is con... Consider a semiparametric regression model with linear time series errors Y_k= x′ _kβ + g(t_k) + ε_k, 1 ≤ k ≤ n, where Y_k's are responses, x_k =(x_(k1),x_(k2),···,x_(kp))′ and t_k ∈ T is contained in R are fixed design points, β =(β_1,β_2,···,β_p)′ is an unknown parameter vector, g(·) is an unknown bounded real-valuedfunction defined on a compact subset T of the real line R, and ε_k is a linear process given byε_k = ∑ from j=0 to ∞ of ψ_je_(k-j), ψ_0=1, where ∑ from j=0 to ∞ of |ψ_j| < ∞, and e_j,j=0, +-1, +-2,···, ard i.i.d. random variables. In this paper we establish the asymptoticnormality of the least squares estimator of β, a smooth estimator of g(·), and estimators of theautocovariance and autocorrelation functions of the linear process ε_k. 展开更多
关键词 semiparametric regression model fixed-design asymptotic normality lineartime series errors
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Energy System Selection for Small Underwater Vehicles 被引量:2
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作者 G.T.Reader J.G.Hawley 《Journal of Thermal Science》 SCIE EI CAS CSCD 1994年第1期7-14,共8页
The oceans cover almost three-quarters of the earth's surface and provide a highway for commerceor conquest and constitute a rich source of nutrients, materials and energy. The exploration and exploitation of ocea... The oceans cover almost three-quarters of the earth's surface and provide a highway for commerceor conquest and constitute a rich source of nutrients, materials and energy. The exploration and exploitation of oceanic resources accelerated in the 1970s because of the emerging offshore oil and gasindustry. The extraction and national protection of these and other resources will increase rapidlyin the next century and in support of these activities one of the most useful tools will be the smallunderwater vehicle. However, if these vehicles are to carry out the envisaged tasks in a cost--effectiveand mission-effective manner they will require high performance energy systems. A number of suchsystems are being developed and the problem arises as which one to select for a particular task. In thispaper the development of software based techniques for the selection of energy systems is described. 展开更多
关键词 energy system selection small underwater vehicles
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Visual remote sensing image fusion using local correlation moment
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作者 杨旭红 敬忠良 +1 位作者 李建勋 HenryLeung 《Chinese Optics Letters》 SCIE EI CAS CSCD 2004年第9期516-519,共4页
In this paper a fusion method is proposed for merging a high-resolution panchromatic image and a lowresolution multispectral image. The algorithm is based on discrete wavelet transform (DWT). It uses correlation momen... In this paper a fusion method is proposed for merging a high-resolution panchromatic image and a lowresolution multispectral image. The algorithm is based on discrete wavelet transform (DWT). It uses correlation moment rule to the low frequency bands and local deviation rule to the high frequency bands separately. Experimental results indicate that the proposed approach outperforms the traditional methods. 展开更多
关键词 Correlation methods Image processing Remote sensing Wavelet transforms
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Iterative Weighted Semiparametric Least Squares Estimation in Repeated Measurement Partially Linear Regression Models
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作者 GemaiChen Jin-hongYou 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2005年第2期177-192,共16页
Consider a repeated measurement partially linear regression model with anunknown vector parameter β_1, an unknown function g(·), and unknown heteroscedastic errorvariances. In order to improve the semiparametric... Consider a repeated measurement partially linear regression model with anunknown vector parameter β_1, an unknown function g(·), and unknown heteroscedastic errorvariances. In order to improve the semiparametric generalized least squares estimator (SGLSE) of ,we propose an iterative weighted semiparametric least squares estimator (IWSLSE) and show that itimproves upon the SGLSE in terms of asymptotic covariance matrix. An adaptive procedure is given todetermine the number of iterations. We also show that when the number of replicates is less than orequal to two, the IWSLSE can not improve upon the SGLSE. These results are generalizations of thosein [2] to the case of semiparametric regressions. 展开更多
关键词 Partially linear regression model heteroscedastic error variance iterativeweighted semiparametric least squares estimator (IWSLSE) asymptotic normality
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Uniform Convergence Rate of Estimators of Autocovariances in Partly Linear Regression Models with Correlated Errors
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作者 Jin-hongYou GemaiChen +1 位作者 MinChen ue-leiJiang 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2003年第3期363-370,共8页
Consider the partly linear regression model , where y <SUB>i </SUB>’s are responses, are known and nonrandom design points, is a compact set in the real line , &#946; = (&#946; <SUB>1<... Consider the partly linear regression model , where y <SUB>i </SUB>’s are responses, are known and nonrandom design points, is a compact set in the real line , &#946; = (&#946; <SUB>1</SUB>, ··· , &#946; <SUB>p </SUB>)' is an unknown parameter vector, g(·) is an unknown function and {&#949; <SUB>i </SUB>} is a linear process, i.e., , where e <SUB>j </SUB>are i.i.d. random variables with zero mean and variance . Drawing upon B-spline estimation of g(·) and least squares estimation of &#946;, we construct estimators of the autocovariances of {&#949; <SUB>i </SUB>}. The uniform strong convergence rate of these estimators to their true values is then established. These results not only are a compensation for those of [23], but also have some application in modeling error structure. When the errors {&#949; <SUB>i </SUB>} are an ARMA process, our result can be used to develop a consistent procedure for determining the order of the ARMA process and identifying the non-zero coeffcients of the process. Moreover, our result can be used to construct the asymptotically effcient estimators for parameters in the ARMA error process. 展开更多
关键词 Uniform strong convergence rate autocovariance and autocorrelation B-spline estimation correlated error partly linear regression model
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