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211.
文章基于兰新铁路沿线砂石料碱活性调查,介绍了混凝土碱-骨料反应的危害和集料碱活性试验方法,提出了一系列预防混凝土碱-骨料反应的措施,并进行了双掺粉煤灰和矿渣粉抑制碱-骨料反应的试验研究。研究结果表明:粉煤灰和矿渣粉掺入量在10%以上,可有效防止碱-骨料反应的发生,对优化兰新铁路高性能混凝土配合比具有参考价值。 相似文献
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213.
基于蠕变试验路堤工后沉降的数值模拟 总被引:1,自引:1,他引:0
研究目的:为了保持轨道的平顺性和稳定性,高速铁路要求路堤的工后沉降为零沉降,而红层属于C类填料,易崩解、软化,此研究为了验证将红层粉碎后作为高速铁路路堤填料的可行性。
研究方法:将红层填料经过粉碎(小于2mm以下),同时将试样的密实度提高到95%,对试样采用逐级单轴加载,每一级加载为一个月左右,直到试样破坏;同时以逐级加载的压缩蠕变曲线试验结果为基础,对蠕变曲线的减速段采用K—K—H模型进行拟合,根据拟合的结果,采用数值模拟对填筑高度为10m路堤的工后沉降进行了预测。研究结果:由数值模拟结果知,路堤顶部的一年工后沉降为4mm,并在40d左右达到稳定状态。
研究结论:其结果论证了采用红层作为填料经过一定的施工工艺后能满足路堤工后零沉降的要求。 相似文献
214.
张晓怡 《铁路工程造价管理》2013,(6):23-25
在激烈的市场竞争中,企业如何通过技术创新,提高工效和管理水平,降低成本,增强核心竞争力,促进企业的发展和壮大,是一个永久的话题。不少企业按照项目管理体系和标准,在组织管理模式上进行创新和变革,将企业职能式管理模式转变为项目团队管理模式,组建高绩效项目管理团队,对具体项目进行实施和管理。此文针对高绩效项目团队的基本特征,阐述选用高素质项目经理和组建高绩效项目管理团队的条件,如何进行绩效考核和预防风险,保证项目的顺利实施,实现计划目标。 相似文献
216.
通过对地下水渗流场的理论分析,结合宜万线齐岳山隧道高水压富水地段现场具体处理情况,得出高水压富水隧道设计应注意的主要原则:"以堵为主,限量排放"是高水位富水隧道设计应遵循的基本原则,限量标准应根据隧道区域内具体情况类比确定;地层注浆是实现限量排放的主要方式,确定注浆加固圈范围时应确保注浆帷幕体自身的稳定;排水系统是衬砌结构设计中不可缺少的一部分,在完善可靠的排水系统下,衬砌结构承受的外水荷载能较大幅度地进行折减。 相似文献
217.
Mesoscale high-frequency variability in the Alboran Sea and its influence on fish larvae distributions 总被引:2,自引:0,他引:2
This work analyses a multidisciplinary data set including hydrological and meteorological data, satellite images, and fish larvae abundance from a high-frequency experiment conducted along a north–south transect across the Western Alboran Sea anticyclonic gyre. Four consecutive occupations of the transect, crossing the frontal area, evidenced the high-frequency variability of hydrological structures and its influence on the latitudinal and vertical distribution of fish larvae in a period of a few days. The influence of dynamical processes on fish larvae depends on the location of the spawning as well as on the larval fish position in the water column. Wind induced upwelling and/or the southward drift of the Atlantic current transport larvae of neritic species, such as Sardina pilchardus and Engraulis encrasicolus to open sea areas. At the same time, these events bring about alterations in the latitudinal and vertical distributions of mesopelagic fish larvae. The species with a relatively surface distribution, as Ceratoscopelus maderensis, were transported and accumulated to the south of the Atlantic Jet (AJ), while those with a deeper distribution in the water column, as Maurolicus muelleri or Benthosema glaciale, would be upwelled and concentrated to the north. This study shows that it is difficult to extract conclusions about the mean or preferential distributions of fish larvae when one single/synoptic survey is considered and that time evolution of hydrological structures has to be considered in order to conclude. 相似文献
218.
This paper formulates a generalized heterogeneous data model (GHDM) that jointly handles mixed types of dependent variables—including multiple nominal outcomes, multiple ordinal variables, and multiple count variables, as well as multiple continuous variables—by representing the covariance relationships among them through a reduced number of latent factors. Sufficiency conditions for identification of the GHDM parameters are presented. The maximum approximate composite marginal likelihood (MACML) method is proposed to estimate this jointly mixed model system. This estimation method provides computational time advantages since the dimensionality of integration in the likelihood function is independent of the number of latent factors. The study undertakes a simulation experiment within the virtual context of integrating residential location choice and travel behavior to evaluate the ability of the MACML approach to recover parameters. The simulation results show that the MACML approach effectively recovers underlying parameters, and also that ignoring the multi-dimensional nature of the relationship among mixed types of dependent variables can lead not only to inconsistent parameter estimation, but also have important implications for policy analysis. 相似文献
219.
Zhi-Sheng Xie Xin-Jun Xu Chun-Yan Xie Jie-Yun Huang Mei Yang Rui-Ming Li Xiao Chen 《西安交通大学学报(英文版)》2011,1(3)
A reversed phase high performance liquid chromatography (HPLC) method was established for the simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. A Grace Apollo Cl8 column (250 mm × 4.6 mm, 5 μm) was used as the stationary phase and the mobile phase was composed of acetonitrile and aqueous phosphoric acid (0.2%, v/v). Gradient elution was carried out at the flow rate of 1.0 mL/min and the column temperature was 30 ℃. An ultraviolet (UV) detector was used with a selected wavelength of 240 nm. Calibration curves were linear within the concentration range of 4.6-45.75 μg/mL for 12, 13-dihydroxyeuparin (r〉0.9999) and 106.9-1068.9μg/mL for glycyrrhizic acid (r〉0.9999), respectively. Recoveries were 102.18% for 12, 13-dihydroxyeuparin and 101.17% for glycyrrhizic acid. The method developed could be applied to the simultaneous determination of 12, 13- dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. 相似文献
220.
技术创新是企业可持续发展的源动力,是提高勘察设计企业竞争能力的有效方式。从技术创新理论入手,分析了影响企业技术创新的因素,阐述了高新技术产业化对企业技术创新的推动作用,为勘察设计企业走高新技术产业化道路提供参考。 相似文献