人力资本投资、素质与就业

人力资本是国家经济可持续发展的重要因素,也是社会进步的必要条件,加强人力资本的投资,提高人员的素质,改善就业环境,是当今社会主义市场经济下的紧要任务,只有加强人力资本的投资、改善正规学校教育、职业教育和再就业培训,才能从根本上解决就业问题,为我国的经济发展与社会稳定做出保障。     

A Novel Two-step Frequency Offset Estimator for OFDM

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.     

电子倍增CCD在天基空间监视中的应用

天基空间监视是地基空间监视的延伸,需要高性能CCD作为成像器。首先回顾CCD的发展．并分析天基空间监视对CCD的技术需求。电子倍增CCD是超低读出噪声和高量子效率的新型器件。说明电子倍增CCD的原理．并介绍CCD97在天基空间监视中的应用分析。讨论电子倍增CCD在空间监视中的应用技术,如倍增增益的控制及器件格式拼接等。