Aiming at the shortcoming that certain existing blockingmatching algorithrns, such as full search, three-step search, and dia- mond search algorithms, usually can not keep a good balance between high acoaracy and low ...Aiming at the shortcoming that certain existing blockingmatching algorithrns, such as full search, three-step search, and dia- mond search algorithms, usually can not keep a good balance between high acoaracy and low computational complexity, a block-maching motion estimation algorithm based on two-step search is proposed in this paper. According to the fact that the gray values of adjacent pixels will not vary fast, the algorithm employs an interlaced search pattem in the search window to estimate the motion vector of the objectblock. Simulation and actual experiments demanstrate that the proposed algmithm greatly outperforms the well-known three-step search and dianond search algoritlam, no matter the motion vector is large or small. Comparedc with the full search algorithm, the proposed one achieves similar peffomance but requires much less computation, therefore, the algorithm is well qualified for real-time video image processing.展开更多
Quadratic distance estimation making use of the sample quantile function over a continuous range is introduced. It extends previous methods which are based only on a few sample quantiles and it parallels the continuou...Quadratic distance estimation making use of the sample quantile function over a continuous range is introduced. It extends previous methods which are based only on a few sample quantiles and it parallels the continuous GMM method. Asymptotic properties are established for the continuous quadratic distance estimators (CQDE) and the implementation of the methods are discussed. The methods appear to be useful for balancing robustness and efficiency and useful for fitting distribution with model quantile function being simpler than its density function or distribution function.展开更多
Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fi...Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fine estimate and coarse estimate. In the first step, the fine estimation is performed based on the principle of minimum variance. However, the fine estimation has ambiguity since its estimate range is limited. In the second step, the coarse estimation is obtained, which results in a larger estimate range but less precision. Using the coarse estimation, the ambiguity of fine estimation is resolved. To fully use the correlation among L identical parts, the fine estimation resolved the ambiguity and the coarse estimation are optimally combined to obtain the final estimation. Furthermore, the estimation variance of the proposed method is derived. Simulation results demonstrate that the novel two-step estimator outperforms the conventional two-step estimator in terms of estimate performance and computational complexity.展开更多
基于惩罚广义矩估计(generalized method of moments,GMM)的正交投影估计方法,文章针对一类部分线性可加空间自回归模型提出了一种变量选择方法。该方法既能在参数分量中选取重要的协变量,又能识别空间效应的显著性。在一定条件下,文章...基于惩罚广义矩估计(generalized method of moments,GMM)的正交投影估计方法,文章针对一类部分线性可加空间自回归模型提出了一种变量选择方法。该方法既能在参数分量中选取重要的协变量,又能识别空间效应的显著性。在一定条件下,文章亦证明了该方法的相合性,并得到了参数估计量的收敛速度,最后通过蒙特卡罗模拟研究证实了该方法在有限样本下的可行性。展开更多
欧美发达国家债务危机的频繁发生引起国际社会的广泛关注与思考,对其内在原因的深入探讨迅速成为学术界的研究焦点。文章从国防支出的角度出发,通过构建政府债务的动态面板模型,考察国防支出与政府债务之间的关系。以1991—2013年15个...欧美发达国家债务危机的频繁发生引起国际社会的广泛关注与思考,对其内在原因的深入探讨迅速成为学术界的研究焦点。文章从国防支出的角度出发,通过构建政府债务的动态面板模型,考察国防支出与政府债务之间的关系。以1991—2013年15个经济合作与发展组织(organization for economic co-operation and development,OECD)国家为样本,利用两步法系统广义矩估计(generalized method of moments,GMM)进行面板估计,从而得到比之前研究更稳健的估计量。结果表明,经济状况对政府债务规模有显著的消极影响,相反国防支出对其则有显著的积极影响,且作用力度是经济发展状况的4倍多。发达国家可通过适度削减国防开支、大力推动经济发展等措施达到控制债务规模、化解债务危机的目的。展开更多
基金supported by the Lab Open Fund of Beijing Microchemical Research Institute(P2008026EB)
文摘Aiming at the shortcoming that certain existing blockingmatching algorithrns, such as full search, three-step search, and dia- mond search algorithms, usually can not keep a good balance between high acoaracy and low computational complexity, a block-maching motion estimation algorithm based on two-step search is proposed in this paper. According to the fact that the gray values of adjacent pixels will not vary fast, the algorithm employs an interlaced search pattem in the search window to estimate the motion vector of the objectblock. Simulation and actual experiments demanstrate that the proposed algmithm greatly outperforms the well-known three-step search and dianond search algoritlam, no matter the motion vector is large or small. Comparedc with the full search algorithm, the proposed one achieves similar peffomance but requires much less computation, therefore, the algorithm is well qualified for real-time video image processing.
文摘Quadratic distance estimation making use of the sample quantile function over a continuous range is introduced. It extends previous methods which are based only on a few sample quantiles and it parallels the continuous GMM method. Asymptotic properties are established for the continuous quadratic distance estimators (CQDE) and the implementation of the methods are discussed. The methods appear to be useful for balancing robustness and efficiency and useful for fitting distribution with model quantile function being simpler than its density function or distribution function.
基金Foundation of Donghua University,China (No.104100044027)
文摘Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fine estimate and coarse estimate. In the first step, the fine estimation is performed based on the principle of minimum variance. However, the fine estimation has ambiguity since its estimate range is limited. In the second step, the coarse estimation is obtained, which results in a larger estimate range but less precision. Using the coarse estimation, the ambiguity of fine estimation is resolved. To fully use the correlation among L identical parts, the fine estimation resolved the ambiguity and the coarse estimation are optimally combined to obtain the final estimation. Furthermore, the estimation variance of the proposed method is derived. Simulation results demonstrate that the novel two-step estimator outperforms the conventional two-step estimator in terms of estimate performance and computational complexity.
文摘基于惩罚广义矩估计(generalized method of moments,GMM)的正交投影估计方法,文章针对一类部分线性可加空间自回归模型提出了一种变量选择方法。该方法既能在参数分量中选取重要的协变量,又能识别空间效应的显著性。在一定条件下,文章亦证明了该方法的相合性,并得到了参数估计量的收敛速度,最后通过蒙特卡罗模拟研究证实了该方法在有限样本下的可行性。
文摘欧美发达国家债务危机的频繁发生引起国际社会的广泛关注与思考,对其内在原因的深入探讨迅速成为学术界的研究焦点。文章从国防支出的角度出发,通过构建政府债务的动态面板模型,考察国防支出与政府债务之间的关系。以1991—2013年15个经济合作与发展组织(organization for economic co-operation and development,OECD)国家为样本,利用两步法系统广义矩估计(generalized method of moments,GMM)进行面板估计,从而得到比之前研究更稳健的估计量。结果表明,经济状况对政府债务规模有显著的消极影响,相反国防支出对其则有显著的积极影响,且作用力度是经济发展状况的4倍多。发达国家可通过适度削减国防开支、大力推动经济发展等措施达到控制债务规模、化解债务危机的目的。
