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181.
182.
We find that the solar cycles 9, 11, and 20 are similar to cycle 23 in their respective descending phases. Using this similarity and the observed data of smoothed monthly mean sunspot numbers (SMSNs) available for the descending phase of cycle 23, we make a date calibration for the average time sequence made of the three descending phases of the three cycles, and predict the start of March or April 2008 for cycle 24. For the three cycles, we also find a linear correlation of the length of the descending phase of a cycle with the difference between the maximum epoch of this cycle and that of its next cycle.Using this relationship along with the known relationship between the rise-time and the maximum amplitude of a slowly rising solar cycle, we predict the maximum SMSN of cycle 24 of 100.2±7.5 to appear during the period from May to October 2012. 相似文献
183.
Zhengfang Wu Haibo Du Dongsheng Zhao Ming Li Xiangjun Meng Shengwei Zong 《Theoretical and Applied Climatology》2012,108(3-4):495-503
Daily global solar radiation is an important input required in most crop models. In the present study, a sunshine-based model, the ?ngstr?m–Prescott model, is employed to estimate daily global solar radiation on a horizontal surface during the growing season in Northeast China. Data from six control groups are used. The controls include the entire sequence, precipitation days, and non-precipitation days both during the growing season and year-round. Estimations are validated by comparing the calculated values with the corresponding measured values. The results indicate that estimating daily global solar radiation during the growing season using data only from the growing season is better than using year-round data. Classifying days with respect to precipitation and non-precipitation is also unnecessary. The performance on estimating daily global solar radiation during the growing season using the entire data in growing season performs best. A sunshine-based equation is obtained using our method to estimate growing season daily radiation for all meteorological stations in Northeast China. The approved approach is expected to be beneficial to crop models and other agricultural purposes. 相似文献
184.
目前在使用SL2—1型雨量传感器的自动气象站中,存在有明显降水时无降水量、无降水时有降水量以及雨量有明显偏差等异常现象,从传感器上分析其产生原因,并提出故障排除方法。 相似文献
185.
在硫酸介质中,痕量钒(Ⅴ)能明显催化过氧化氢氧化亮绿SF褪色,通过研究该反应的最佳实验条件和动力学参数,建立了测定痕量钒的新催化动力学光度法。该方法选择性强、操作简便、快速,其线性范围为0.0~40ng/mL,检出限为5.2ng/L。方法用于水样及茶叶中痕量钒(Ⅴ)的测定,结果满意。 相似文献
186.
Regional Ecological Risk Assessment of Soil Heavy Metals in Pearl River Delta Economic Zone Based on Different Land Uses 总被引:1,自引:0,他引:1
Based on the results of regional eco-geochemical survey in Pearl River Delta Economic Zone and the local land use patterns, two conventional risk assessment models are introduced to evaluate the ecological risk of eight heavy metals in the topsoil (0~20 cm) of Pearl River Delta. The spatial distribution characteristics of risk caused by metals in the region were characterized by GIS. Results show that As、Cd、Cu and Hg in the topsoil are the primary heavy metals posing risk to the Pearl River Delta while Cr and Zn are negligible. Meanwhile, 23.89% of soil samples have a hazard index of more than 1 which suggests that it is likely to cause chronic diseases in the region. The soils with high hazard index are mainly distributed in the Quaternary area. 37.22% of soil samples have a negligible chronic risk level, of which the spatial distribution is consistent with granite area. Moreover, the spatial distribution of carcinogenic risk is similar to chronic risk, where 25.68% of samples exceed the cancer risk index (1×10-4) recommended by USEPA. Furthermore, the evaluation results presented at administrative units indicate that there are both higher chronic and cancer risk in Panyu and Nansha district where more attentions should be paid to. 相似文献
187.
低周反复荷载作用下矩形钢管混凝土柱与钢梁连接节点的受力性能 总被引:13,自引:3,他引:10
本文进行了2种矩形钢管混凝土柱与钢梁连接节点——翼缘全螺栓(BFP)连接节点与外加强环(WFP-BW)连接节点在柱端低周反复荷载作用下的抗震性能试验,分析比较了这2类节点与焊接翼缘板(WFP)连接节点在不同轴压比下的滞回性能、强度与刚度退化、延性比与耗能比、破坏机理与破坏特征,得出了一些有参考价值的结论。 相似文献
188.
Huai Cheng Zaicong Wang Kang Chen Keqing Zong Zongqi Zou Tao He Zhaochu Hu Mario Fischer‐Gdde Yanhong Liu 《Geostandards and Geoanalytical Research》2019,43(4):663-680
Determination of gold abundances in natural rock is critical for applications, but very challenging. Here, we report a method for determining gold with a very low mass fraction (> 0.01 ng g?1) in rocks. The method involves Carius tube digestion with reverse aqua regia, chromatographic separation to remove most of the sample matrix and measurement by high‐sensitivity ICP‐MS. The mono‐isotopic element gold was quantified by external calibration using an internal standardisation of gold to platinum that was precisely determined by isotope dilution. The method is robust and the obtained results are indistinguishable (< 5–10%, 2s) from those independently obtained by a standard addition technique on the same solution. The results from reference materials TDB‐1 and GPt‐2 are consistent with the certified values and those determined by HF‐aqua regia digestion, confirming the validity of the method. TDB‐1 (n = 20), GPt‐2 (n = 6), BHVO‐2 (n = 9) and other mafic RMs are homogenous for gold (10–20%, 2s) at the 2 g test portion level; however, sample heterogeneity affects some RMs. Gold and platinum‐group elements also display different extents of sample heterogeneity for different RMs. Given the homogeneity observed for TDB‐1, GPt‐2 and BHOV‐2, they are recommended as well‐suited RMs for inter‐laboratory comparison studies of gold. 相似文献
189.
Wei Kuisheng Li Daliang Zhang Shoupeng Hao Yunqing Department of Energy Geology China University of Geosciences Beijing Du Zhenchuan Department of Energy Resomces Geology Hebei Technology University Handan Zong Guoho 《中国地质大学学报(英文版)》2001,12(4)
INTRODUCTIONSequence stratigraphy, an efficient technique for both thebasin analysis and the prediction of hidden oil and gas reser-voir, was traced to seismic stratigraphy founded in l977, andnow has become a separate academic discipline after years ofamendments. In the 26th AAPG, the sedimentary se(1[I(>ncewas defined and the seismic stratigraphy technique was estaI)-lished to characterize and interpret seismic reflection scction.The sequence stratigraphy was emphasized to confirm and… 相似文献
190.