镉标准溶液配制结果的不确定度评定   总被引：4，自引：2，他引：2  

李松  饶竹 《岩矿测试》2009,28(5):479-482

选择氧化镉标准物质,配制成质量浓度为1000μg/mL的镉标准溶液,利用等离子体质谱法对标准溶液进行了定值与稳定性检验。通过对镉标准溶液配制过程不确定因素的描述,以95%概率下的扩展因子2获得标准溶液浓度配制标示值的扩展不确定度。实验数据表明,所配制的标准溶液稳定性可达2年。  相似文献   

Linear and nonlinear vibration of non-uniform beams on two-parameter foundations using p-elements     

B. Zhu  A.Y.T. Leung 《Computers and Geotechnics》2009

A hierarchical finite element is presented for the geometrically nonlinear free and forced vibration of a non-uniform Timoshenko beam resting on a two-parameter foundation. Legendre orthogonal polynomials are used as enriching shape functions to avoid the shear-locking problem. With the enriching degrees of freedom, the accuracy of the computed results and the computational efficiency are greatly improved. The arc-length iterative method is used to solve the nonlinear eigenvalue equation. The computed results of linear and nonlinear vibration analyses show that the convergence of the proposed element is very fast with respect to the number of Legendre orthogonal polynomials used. Since the elastic foundation and the axial load applied at both ends of the beam affect the ratios of linear frequencies associated with the internal resonance, they influence the nonlinear vibration characteristics of the beam. The axial tensile stress of the beam in nonlinear vibration is investigated in this paper, and attention should be paid to the geometrically nonlinear vibration resulting in considerably large axial tensile stress in the beam.  相似文献   

Tectonics of the offshore Red River Fault recorded in the junction of the Yinggehai and Qiongdongnan Basins     

Lei  Chao  Ren  Jianye  Pei  Jianxiang  Liu  Bowen  Zuo  Xiang  Liu  Jiaao  Zhu  Shiguo 《中国科学:地球科学(英文版)》2021,64(11):1893-1908

Science China Earth Sciences - The Red River Fault, which originated from the southeastern margin of the Tibetan Plateau, has a great significance for obtaining a further understanding of the...  相似文献   

矿山巷道三维建模数据组织与算法研究     

侯建光  朱月霞  宋震 《国土资源信息化》2014,(5):29-33

巷道作为矿山的重要组成部分,在矿山开发建设过程中发挥着重要作用,基于虚拟现实技术的巷道三维模拟能够为采矿工程、安全生产、施工、人员及设备管理等提供直观的数据展示和决策支持,其精确程度直接影响着矿山的工程质量与采选能力。本文主要探讨巷道三维建模数据组织方法,直壁拱形断面巷道三维建模的关键算法,并基于实验数据,利用OGRE三维引擎技术完成巷道三维自动建模,验证了数据组织和算法的有效性和优越性。  相似文献   

叶面积指数的快速测定方法——植被定量遥感的地面标定技术   总被引：9，自引：0，他引：9  

张仁华  孙晓敏  朱治林 《国土资源遥感》1998,9(1):54-60

本文论述了用“底视法”测量叶面积指数的基本原理,并在中国科学院禹城综合试验站遥感试验场以“冠层分析仪”对该方法进行了试验,提出了刺柏针叶叶面积指数的新估算方法。通过计算证明,测定值和估算值具有较好的一致性。这种以“底视法”为基础的冠层分析仪可以用于植被定量遥感的快速地面定标。  相似文献   

Mg isotopic heterogeneity,Al‐Mg isochrons,and canonical 26Al/27Al in the early solar system     

G. J. WASSERBURG  Josh WIMPENNY  Qing‐Zhu YIN 《Meteoritics & planetary science》2012,47(12):1980-1997

There is variability in the Mg isotopic composition that is a reflection of the widespread heterogeneity in the isotopic composition of the elements in the solar system at approximately 100 ppm. Measurements on a single calcium‐aluminum‐rich inclusion (CAI) gave a good correlation of ²⁶Mg/²⁴Mg with ²⁷Al/²⁴Mg, yielding an isochron corresponding to an initial (²⁶Al/²⁷Al)_o = (5.27 ± 0.18) × 10^?5 and an initial (²⁶Mg/²⁴Mg)_o = ?0.127 ± 0.032‰ relative to the standard. This isochron is parallel to that obtained by Jacobsen et al. (2008) , but is distinctively offset. This demonstrates that there are different initial Mg isotopic compositions in different samples with the same ²⁶Al/²⁷Al. No inference about uniformity/heterogeneity of ²⁶Al/²⁷Al on a macro scale can be based on the initial (²⁶Mg/²⁴Mg)_o values. Different values of ²⁶Al/²⁷Al for samples representing the same point in time would prove heterogeneity of ²⁶Al/²⁷Al. The important issue is whether the bulk solar inventory of ²⁶Al/²⁷Al was approximately 5 × 10^?5 at some point in the early solar system. We discuss ultra refractory phases of solar type oxygen isotope composition with ²⁶Al/²⁷Al from approximately 5 × 10^?5 to below 0.2 × 10^?5. We argue that the real issues are: intrinsic heterogeneity in the parent cloud; mechanism and timing for the later production of ¹⁶O‐poor material; and the relationship to earlier formed ¹⁶O‐rich material in the disk. ²⁶Al‐free refractories can be produced at a later time by late infall, if there is an adequate heat source, or from original heterogeneities in the placental molecular cloud from which the solar system formed.  相似文献   

Short-Term Periodicity in Solar Mean Magnetic Field during Activity Maximum and Minimum Periods     

N. Ye  F. R. Zhu  X. M. Zhou  H. Y. Jia 《Solar physics》2012,279(2):411-418

The short-term periodicity in the solar mean magnetic field (SMMF) observed at the Wilcox Solar Observatory during the last four activity cycles is investigated by using Lomb?CScargle periodograms. Our results show that the SMMF has main periods of about 27, 13.5, and 9 days in both the maximum and minimum years of each activity cycle. The SMMF has the most dominant period of about 27 days during the activity maxima. However, during the activity minimum years the 13.5-day periodicity is the most significant, except for the minimum of 1984??C?1986. These results indicate that the distribution of active regions in the activity maximum years is quite different from that in the minimum years.  相似文献   

基于皮肤转录组的半滑舌鳎无眼侧黑化相关基因的筛选鉴定     

赵娜  何晓旭  贾磊  朱春华  张博 《海洋学报》2022,44(2):57-66

半滑舌鳎(Cynoglossus semilaevis)作为比目鱼(Pleuronectiformes)中的代表物种,是我国沿海地区重要的海水经济鱼类.半滑舌鳎体色异常的问题长期以来一直困扰着从业者.导致体色变化的原因多种多样,遗传因素是最根本原因.针对半滑舌鳎无眼侧黑化的研究多在环境、营养、生理、常见色素基因克隆等方...  相似文献   

地下爆炸各向同性源和补偿线性矢量偶极源共同作用对Rg波低谷点的影响          下载免费PDF全文

王旭亮  靳平  朱号锋  徐恒垒  徐雄 《地震学报》2021,43(6):745-752

本文利用地震面波激发理论计算了两种震源不同相对强度、相对埋深及源时间函数情况下的Rg波频谱,研究地下爆炸中各向同性（ISO）源和补偿线性矢量偶极（CLVD）源共同激发的Rg波信号低谷点特性。结果表明,由于两种震源相对强度、相对埋深及源频谱的影响,混合信号低谷点频率与单一CLVD源激发的信号有很大差异,因此实际地下爆炸中低谷点频率与CLVD源埋深不能单纯地满足理论的反比关系,直接用理论式估算地下爆炸埋深是不足的。   相似文献   

基于Elman神经网络算法的地震经济损失快速评估研究     

郑韵  杨天青  王青平  郑超  朱耿青  魏娟 《中国地震》2021,37(3):610-619

地震经济损失快速评估是应急救灾的重要决策依据。本文选取了震级、极震区烈度、极震区烈度和抗震设防烈度之差ΔI、人口密度、人均GDP等5个指标作为输入层节点,将地震灾害的直接经济损失作为输出层节点,通过对1996—2013年的地震灾害损失资料进行训练和仿真分析,构建了Elman神经网络地震经济损失快速估计模型。运用该模型,对近年来的7个破坏性地震的直接经济损失进行评估分析,评估结果和实际直接经济损失有较好的一致性,该方法为地震经济损失快速评估提供了一种新思路。  相似文献