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试论语言是人类最重要的交际工具
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作者 周楠 吕璀璨 《魅力中国》 2014年第18期238-238,共1页
近年来,语言在发展的过程中也受到了一定的破坏,一些语言濒临灭绝。那么。语言作为一项交际工具,对于人类而言,还具有重要巨吗?本文就是通过语言的概念及起源、语言作为交际工具的最重要性、语言在古时今日的最重要性三方面入手。... 近年来,语言在发展的过程中也受到了一定的破坏,一些语言濒临灭绝。那么。语言作为一项交际工具,对于人类而言,还具有重要巨吗?本文就是通过语言的概念及起源、语言作为交际工具的最重要性、语言在古时今日的最重要性三方面入手。对语言的发展进行了横向与纵向的比较。试论证了语言是人类最重要的交际工具。 展开更多
关键词 语言 概念及起源 交际工具 古今 最重要性
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Passive source localization using importance sampling based on TOA and FOA measurements 被引量:4
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作者 Rui-rui LIU Yun-long WANG +2 位作者 Jie-xin YIN Ding WANG Ying WU 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2017年第8期1167-1179,共13页
Passive source localization via a maximum likelihood (ML) estimator can achieve a high accuracy but involves high calculation burdens, especially when based on time-of-arrival and frequency-of-arrival measurements f... Passive source localization via a maximum likelihood (ML) estimator can achieve a high accuracy but involves high calculation burdens, especially when based on time-of-arrival and frequency-of-arrival measurements for its internal nonlinearity and nonconvex nature. In this paper, we use the Pincus theorem and Monte Carlo importance sampling (MCIS) to achieve an approximate global solution to the ML problem in a computationally efficient manner. The main contribution is that we construct a probability density function (PDF) of Gaussian distribution, which is called an important function for efficient sampling, to approximate the ML estimation related to complicated distributions. The improved performance of the proposed method is at- tributed to the optimal selection of the important function and also the guaranteed convergence to a global maximum. This process greatly reduces the amount of calculation, but an initial solution estimation is required resulting from Taylor series expansion. However, the MCIS method is robust to this prior knowledge for point sampling and correction of importance weights. Simulation results show that the proposed method can achieve the Cram6r-Rao lower bound at a moderate Gaussian noise level and outper- forms the existing methods. 展开更多
关键词 Passive source localization Time of arrival (TOA) Frequency of arrival (FOA) Monte Carlo importance sampling(MCIS) Maximum likelihood (ML)
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AMERICAN OPTION PRICING UNDER GARCH DIFFUSION MODEL: AN EMPIRICAL STUDY 被引量:2
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作者 WU Xinyu YANG Wenyu +1 位作者 MA Chaoqun ZHAO Xiujuan 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2014年第1期193-207,共15页
The GARCH diffusion model has received much attention in recent years, as it describes financial time series better when compared to many other models. In this paper, the authors study the empirical performance of Ame... The GARCH diffusion model has received much attention in recent years, as it describes financial time series better when compared to many other models. In this paper, the authors study the empirical performance of American option pricing model when the underlying asset follows the GARCH diffusion. The parameters of the GARCH diffusion model are estimated by the efficient importance sampling-based maximum likelihood (EIS-ML) method. Then the least-squares Monte Carlo (LSMC) method is introduced to price American options. Empirical pricing results on American put options in Hong Kong stock market shows that the GARCH diffusion model outperforms the classical constant volatility (CV) model significantly. 展开更多
关键词 American option efficient importance sampling GARCH diffusion model least-squaresMonte Carlo maximum likelihood.
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