保障教学科研信息的丰富与畅通是高校图书馆的根本使命。在概述美国版权结算中心的即时获取(Get It Now)服务的基础上,聚焦其在美国高校图书馆的应用,通过对实践主体、实践过程、实践效果三方面的详细调研,进一步明确其对于图书馆文献...保障教学科研信息的丰富与畅通是高校图书馆的根本使命。在概述美国版权结算中心的即时获取(Get It Now)服务的基础上,聚焦其在美国高校图书馆的应用,通过对实践主体、实践过程、实践效果三方面的详细调研,进一步明确其对于图书馆文献服务和馆藏开发的实际意义,并由此提炼出Get It Now作为一种资源、一项服务和一种工具的创新价值。展开更多
为了引进和推广GET(Methane gas as renewable energy at rice fields tian)技术,并有效改善土壤肥力,开展了基于GET技术的农家肥和水稻秸秆混合厌氧发酵,生产生物甲烷的田间试验。通过对利用和未利用该技术的土壤全氮、全磷、有机质含...为了引进和推广GET(Methane gas as renewable energy at rice fields tian)技术,并有效改善土壤肥力,开展了基于GET技术的农家肥和水稻秸秆混合厌氧发酵,生产生物甲烷的田间试验。通过对利用和未利用该技术的土壤全氮、全磷、有机质含量的测定,探讨了试验过程中农家肥类型(猪粪和牛粪)、水稻秸秆施用量2个试验因子及其交互作用对土壤肥力的影响。试验结果表明,农家肥类型、水稻秸秆施用量及其交互作用均对土壤肥力产生了一定影响。农家肥类型对土壤有机质含量有极显著影响,其中,以猪粪+水稻秸秆处理对土壤有机质含量的促进效果较好,其土壤有机质含量比牛粪+水稻秸秆、水稻秸秆处理分别提高7.67%、29.86%,水稻秸秆处理土壤全氮、全磷含量相比对照分别增加35.72%、 59.97%。水稻秸秆施用量对土壤有机质、全磷含量分别有极显著、显著影响,不同施用量的水稻秸秆使土壤全氮、全磷、有机质含量最高分别增加24.70%、71.12%、156.15%,但水稻秸秆施用量超过100 kg/垄以后,土壤有机质含量的增加不再显著。2种农家肥+水稻秸秆配比中,均以农家肥∶水稻秸秆(质量比)=120∶125对土壤的增肥效果较好。展开更多
This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar（OTHR）. In this method, the sparse time-frequency distribution o...This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar（OTHR）. In this method, the sparse time-frequency distribution of the radar echo is obtained by solving a sparse optimization problem based on the short-time Fourier transform. Then Hough transform is employed to estimate the parameter of the targets. The proposed algorithm has the following advantages： Compared with the Wigner-Hough transform method, the computational complexity of the sparse optimization is low due to the application of fast Fourier transform（FFT）. And the computational cost of Hough transform is also greatly reduced because of the sparsity of the time-frequency distribution. Compared with the high order ambiguity function（HAF） method, the proposed method improves in terms of precision and robustness to noise. Simulation results show that compared with the HAF method, the required SNR and relative mean square error are 8 dB lower and 50 dB lower respectively in the proposed method. While processing the field experiment data, the execution time of Hough transform in the proposed method is only 4% of the Wigner-Hough transform method.展开更多
文摘保障教学科研信息的丰富与畅通是高校图书馆的根本使命。在概述美国版权结算中心的即时获取(Get It Now)服务的基础上,聚焦其在美国高校图书馆的应用,通过对实践主体、实践过程、实践效果三方面的详细调研,进一步明确其对于图书馆文献服务和馆藏开发的实际意义,并由此提炼出Get It Now作为一种资源、一项服务和一种工具的创新价值。
文摘为了引进和推广GET(Methane gas as renewable energy at rice fields tian)技术,并有效改善土壤肥力,开展了基于GET技术的农家肥和水稻秸秆混合厌氧发酵,生产生物甲烷的田间试验。通过对利用和未利用该技术的土壤全氮、全磷、有机质含量的测定,探讨了试验过程中农家肥类型(猪粪和牛粪)、水稻秸秆施用量2个试验因子及其交互作用对土壤肥力的影响。试验结果表明,农家肥类型、水稻秸秆施用量及其交互作用均对土壤肥力产生了一定影响。农家肥类型对土壤有机质含量有极显著影响,其中,以猪粪+水稻秸秆处理对土壤有机质含量的促进效果较好,其土壤有机质含量比牛粪+水稻秸秆、水稻秸秆处理分别提高7.67%、29.86%,水稻秸秆处理土壤全氮、全磷含量相比对照分别增加35.72%、 59.97%。水稻秸秆施用量对土壤有机质、全磷含量分别有极显著、显著影响,不同施用量的水稻秸秆使土壤全氮、全磷、有机质含量最高分别增加24.70%、71.12%、156.15%,但水稻秸秆施用量超过100 kg/垄以后,土壤有机质含量的增加不再显著。2种农家肥+水稻秸秆配比中,均以农家肥∶水稻秸秆(质量比)=120∶125对土壤的增肥效果较好。
基金supported by the National Natural Science Foundation of China(611011726137118461301262)
文摘This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar（OTHR）. In this method, the sparse time-frequency distribution of the radar echo is obtained by solving a sparse optimization problem based on the short-time Fourier transform. Then Hough transform is employed to estimate the parameter of the targets. The proposed algorithm has the following advantages： Compared with the Wigner-Hough transform method, the computational complexity of the sparse optimization is low due to the application of fast Fourier transform（FFT）. And the computational cost of Hough transform is also greatly reduced because of the sparsity of the time-frequency distribution. Compared with the high order ambiguity function（HAF） method, the proposed method improves in terms of precision and robustness to noise. Simulation results show that compared with the HAF method, the required SNR and relative mean square error are 8 dB lower and 50 dB lower respectively in the proposed method. While processing the field experiment data, the execution time of Hough transform in the proposed method is only 4% of the Wigner-Hough transform method.
