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航道公共服务经历了数十年的发展,改正了一些过去的问题,更适应当下数字航道发展的新趋势,正在形成一个全新、有序、有力的长江航道公共服务体系。本文着眼近期重点关注的公共服务领域问题,从对外方面进行了探讨,提出了措施并举出实例,同时在内部管理质量的优化方面也提出了相关的意见。 相似文献
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区域产业结构演化下,三大产业的空间分布特征差异使区域物流需求在空间分布上出现产业关联特性,该分布特征对区域产业布局、物流配套设施配置具有重要的参考价值。以四川省21个州市为研究区域,基于三大产业及各州市物流量数据,采用全局空间自相关、局部空间自相关和回归分析对区域产业发展布局下物流需求发展空间特征进行关联分析,发现三大产业在四川省中部区域形成主要发展区域,并向"东—中—南"横向扩展,受三大产业发展升级的影响,物流需求形成"西南—中部—东北"的斜向发展线。其中第二、三产业发展与地区物流需求发展产生不均衡现象,是未来四川省在二、三产业布局时需要关注的方向。 相似文献
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The new technique that combines wave superposition with the fast Fourier transformation was introduced to simulate the nodal three-dimension relevant wind velocity time series of spatial structures. The wind velocity field where the spatial structure is located is assumed to be homogeneous. The wind‘s power spectral density is divided into frequency spectral function and coherency function and the spectral functions are transformed as the superposition coefficients. The wavelet analysis has excellent localized characters in both time and frequency domains, which not only makes wind velocity time series analysis more accurate, but also can focus on any detail of the objective signal series. The discrete wavelet transformation was adopted to decompose and reconstruct the discrete wind velocity time series. The stability of wavelet analysis for the wind velocity time series was also proved. 相似文献
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Smoothed particle hydrodynamics (SPH) is a useful meshless method. The first and second orders are the most popular derivatives
of the field function in the mechanical governing equations. New methods were proposed to improve accuracy of SPH approximation
by the lemma proved. The lemma describes the relationship of functions and their SPH approximation. Finally, the error comparison
of SPH method with or without our improvement was carried out.
Foundation item: The National Natural Science Foundation of China (No. 50778111); The Key Project of Fund of Science and Technology Development
of Shanghai (No. 07JC14023) 相似文献
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隧道土建结构技术状况直接决定其使用阶段的性能水平,为此,建立一套合理有效的评估方法显得至关重要。当前规范采用最差段落法对隧道土建结构进行评分,为改善规范采用的评分方法,提高土建结构评分的总体性,在深入分析国内外隧道土建结构技术状况评定现状的基础上,按照"普遍反映原则"和"安全原则",提出了基于最差段落评分法的修正方法,细化了隧道土建结构分项与各指标的关系,建立了定性与定量相结合的综合评定标度,实现了规范法中技术状况值与修正法中分项各指标扣分值之间的一一对应关系,得到了一套隧道土建结构技术状况定量评价模型,并结合已有检测评估工程的数据验证了该修正法的有效性。 相似文献