Photographic assessment of retroreflective film properties

Retroreflective film is used widely for target manufacture in close-range photogrammetry, especially where high precision is required for applications in industrial or engineering metrology. 3M Scotchlite 7610 high gain reflective sheeting is the gold standard for retroreflective targets because of the high level of response for incidence angles up to 60°. Retroreflective film is now widely used in the transport industry for signage and many other types of film have become available. This study reports on the performance of six types of retroreflective sheeting, including 7610, based on published metrics for reflectance. Measurements were made using a camera and flash, so as to be directly applicable to photogrammetry. Analysis of the results from this project and the assessment of previous research indicates that the use of standards is essential to enable a valid comparison of retroreflective performance.     

Changes of P, Ca, Al and Fe contents in fringe marshes along a pedogenic chronosequence in the Pearl River estuary, South China

Soil and plant samples were collected in four fringe marsh zones (i.e., A, B, C and D zones) along a pedogenic chronosequence in the Pearl River estuary in the Spring of 2009. Samples were subjected to a total digestion technique and analyzed for P, Ca, Al and Fe in order to study the changes of nutrient contents, storages in soils and their bioavailabilities to wetland plants (e.g. Cyperus malaccensis) in four zones. Results showed that soil Ca increased with depth along soil profiles, while P, Al and Fe generally kept constant in soil profiles in four zones. Al and Fe contents in the top 10 cm soils showed significant decreases from D to A zone, while a significant increase in Ca contents (P<0.05). Significant increases along pedogenic chronosequence for P, Al and Fe at 30-40 cm soil horizons were also observed. Ca was mainly accumulated in plant aboveground parts; Al and Fe were accumulated in the belowground parts; while P was homogenously distributed among the tissues of C. malaccensis. C. malaccensis in D zone had lower Bio-concentration factors (BCFs) of P in the shoots and Al and Fe in the roots, and higher values of Ca in the shoots than those in older zones (P<0.05). Compared to Al and Fe, both Ca and P had relatively higher translocation capacities for C. malaccensis, while only lower TFs for P and higher values for Al and Fe in D zone were observed than those in A and B zones (P<0.05). Except for Al with no significant changes, the total BCFs for P and Fe showed an increasing trend with soil ages, while a decreasing trend for Ca. The total bio-storage factors (TBSFs) of P and Ca declined with the pedogenic time, whereas an increase for Fe. The results of this study can contribute to the wetland conservation and management in the Pearl River estuarine region.     

Geometry Relations with Bed Load Formulae for Alluvial Boundaries

Employing bed load formulae hydraulic geometry relations were derived for stream width, sediment transport velocity, and bed slope. The relations were examined in terms of friction factor, bed load discharge, bed load diameter, and water discharge. Two fundamental approaches to the prediction of hydraulic geometry have been developed. The first and most widely adopted approach is based on empirical equations whereas the second is based on solution of the governing equations of flow. The applied bed load formulae belong to different authors. Here, the comparison with the other derived relations is presented.     

火山岩风化体储层控制因素研究—以三塘湖盆地石炭系卡拉岗组为例

针对火山岩风化壳储层控制因素和成因复杂的难题,以三塘湖盆地石炭系卡拉岗组为例,在搞清晚石炭世构造环境和岩性特征基础上,提出风化淋滤和断裂改造是火山岩风化壳形成有利储层的主要控制因素.不同火山岩岩性经风化淋滤后储层物性均增大并能形成有利储层,储集层孔隙类型以次生溶蚀孔隙和裂缝为主,具双峰分布特征.建立了5层结构模型,并提...     

Assessment of Metal Pollution in Water and Surface Sediments of the Seyhan River,Turkey, Using Different Indexes

The aim of this study was to assess the level of heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination and enrichment in the surface sediments of the Seyhan River, which is the receiving water body of both treated and untreated municipal and industrial effluents as well as agricultural drainage waters generated within Adana, Turkey. Sediment and water samples were taken from six previously determined stations covering the downstream of the Seyhan dam during both wet and dry seasons and the samples were then analyzed for the heavy metals of concern. When both dry and wet seasons were considered, metal concentrations varied significantly within a broad range with Al, 7210–33 967 mg kg^?1 dw; Cr, 46–122 mg kg^?1 dw; Cu, 6–57 mg kg^?1 dw; Fe, 10 294–26 556 mg kg^?1 dw; Mn, 144–638 mg kg^?1 dw; Ni, 82–215 mg kg^?1 dw; Pb, 11–75 mg kg^?1 dw; Zn, 34–146 mg kg^?1 dw in the sediments while Cd was at non‐detectable levels for all stations. For both seasons combined, the enrichment factor (EF) and the geo‐accumulation index (I_geo) for the sediments in terms of the specified metals ranged from 0.56 to 10.36 and ?2.92 to 1.56, respectively, throughout the lower Seyhan River. The sediment quality guidelines (SQG) of US‐EPA suggested the sediments of the Seyhan River demonstrated “unpolluted to moderate pollution” of Cu, Pb, and Zn, “moderate to very strong pollution” of Cr and Ni. The water quality data, on the other hand, indicated very low levels of these metals suggesting that the metal content in the surface sediments were most probably originating from fine sediments transported along the river route instead of water/wastewater discharges with high metal content.     

基于随机二元指标的边坡稳定性分析

考虑岩土体抗剪强度参数的变异性,综合极限平衡法和可靠性理论构建了安全系数概率密度分布函数模型。结合实际工程特点,以安全系数大于临界值为标准构建有效区,将有效区安全系数均值与对应可靠度相乘,得到以安全系数和可靠度为随机二元指标的有效安全系数。以有效安全系数为定量指标,将边坡宏观特征现象与定量分析相联系,构建意义更为明确的边坡稳定性分析及评价方法。通过工程实例对比了有效安全系数与传统评价指标之间的差异。所得结论可为工程建设提供参考和借鉴。     

网格剖分及其精度和计算量分析

网格剖分程度直接影响着地震波正演数值模拟的计算精度及其计算量.以均匀介质模型为例,分析不同网格大小对波场模拟精度和计算量的影响,得出精细化网格剖分是实现高精度地震波正演模拟的有效方法,然而其计算量较大.以均匀倾斜介质模型为例,探讨倾斜地层网格剖分问题,数值实例分析不同震源频率对不同网格剖分方案引起的波场传播精度的影响,...     

多点激励下连续桥梁地震响应特性研究

地震动在强度和频率等方面均具有非平稳特性,导致多跨桥梁的动力响应非常复杂。为了研究多跨连续桥梁在多点地震动激励下的反应,首先提出了评价多点地震动非平稳性的3个指标：幅值绝对值的标准差、方向离散度和穿零率。根据桥梁多点激励运动方程的特点,阐述了广义振型参与系数矩阵的意义,及其与传统振型参与系数矩阵的联系和区别。根据多点地震动非平稳性的特性,对不同支点施加异向及不同幅值的位移或加速度,研究了不同跨数连续梁桥的多点激励响应规律。结果表明,随着连续梁桥跨数的增多,桥梁在多点地震激励下的响应趋于复杂多变,受具体地震动的非平稳性影响越发明显。     

湟源地震台数字地震记录的环境干扰分析及滤波器制作

对湟源地震台周边各种因素所致的地震记录干扰情况进行了分析,认为干扰源主要有采石场爆破、灌溉水渠、小河、车辆干扰及各种天气及固有干扰等。根据这些干扰源的频谱特性,采用MATLAB语言,设计、编制了不同类型的滤波器,在震相识别上发挥了很大作用。