基于X射线荧光光谱法测定少量样品的主次元素

在某些实验中,由于样品来源的有限性,导致样品数量有限,因而有必要探讨少量样品中主次元素的测定方法。X射线荧光光谱法具有样品制备简单、分析速度快、重现性好、测量范围宽和多元素同时进行分析的特点,目前在众多领域中得到了广泛的应用。基于回归曲线法、经验系数法和康普顿散射线内标法求取了各待测元素的工作曲线常数、元素间效应的影响系数和谱重叠系数,并对4 g(32 mm内径,常规)和1 g(10 mm内径,少量)样品测量的精密度和准确度进行了比较分析。结果表明,4 g(32 mm内径,常规)样品测量平均精密度约为1%,1 g(10 mm内径,少量)样品的平均精密度约为3%。测定结果基本能够满足覆盖区多目标地球化学调查样品的质量要求。     

江苏及邻近地区地震视应力特征研究

采用江苏省数字地震台网记录的地震波形资料,利用震源位移谱低频水平与拐角频率计算了2000~2010年江苏及邻近地区561个ML≥1.5中小地震视应力值。结果显示,江苏及邻近地区的地震视应力平均值为0.91 MPa,与中国大陆的平均水平相当。视应力与震级无明显的线性关系,在震级相对较大时表现出一定的高震级对应高视应力的特点。视应力高值地区主要集中在江苏中部至南黄海海域,次高值集中分布在郯庐断裂带中南段的苏鲁交界地区、安徽段固镇至定远附近地区和肥东、巢湖一带,反映了以上地区较高的地震活动水平及地壳应力状态。不同区域ML2震级档视应力的差异性基本反映了区域地质环境、构造活动等特征的差异。     

国产旋转导向及随钻测井系统在渤海某油田的应用

旋转导向和随钻测井系统可在精确、高效控制井眼轨迹和快速识别地层性质的同时大幅度提高作业效率,降低作业成本。尤其在海上油气开发过程中具有较好的提效效果,但是长期以来该领域均被国外石油公司垄断且租赁价格高昂。中海油国产化研制的Welleader旋转导向系统、Drilog随钻测井系统经过多次试验达到了入井应用要求,在渤海某平台调整井钻井作业中进行了应用,结果表明该套系统旋转导向系统轨迹控制满足定向井轨迹要求、测斜数据准确、测井质量符合标准要求,能够实现钻井过程中的轨迹控制和测井要求。     

横断山区垂直带谱的分布模式与坡向效应

根据收集到的横断山区山地垂直带谱数据,对山地垂直带的坡向效应和空间分布规律进行了分析和研究.结果表明:1)主要的垂直带和垂直带界线如林线、暗针叶林带、雪线等的纬度和经度地带性分布规律明显并且分布模式都相似,纬向上呈开口向下的二次曲线分布模式,经向上呈开口向上的二次曲线分布模式,两者共同形成"双曲抛物面"分布模式,充分反映了横断山区的环境与生态的复杂性和独特性,也进一步丰富和发展了山地垂直带谱的二次曲线假说; 2)横断山区山地垂直带谱表现出明显的基于水分驱动的坡向效应,主要表现为同一山体的东、西坡往往具有不同的基带和带谱结构,相同类型的带谱出现的海拔和分布范围不同,迎风坡表现出较为湿润的类型和带谱结构,而背风坡则表现出更为干旱的类型和组成结构;横断山区的坡向效应主要是由于山体对当地盛行季风的影响,造成迎风坡和背风坡水热条件相差很大,从而发育不同的山地垂直带谱类型.从横断山区山地垂直带谱的空间分布规律来看, 28°～29°N、98°～101°E范围内,即大致在澜沧江以东-雅砻江以西,山地垂直带谱普遍表现出干热的特点,为横断山区干热气候的核心地带.但如何定量分析山地的坡向效应尚有待于进一步的研究和讨论.此外、数据质量和数据误差也对分析的结果,尤其是空间分布模式的数学模拟结果产生一定的影响,在以后的研究中尚需进一步完善.     

时变功率谱空间变化性分析

基于我国台湾地区SMART-1密集台阵强震记录资料和Kameda的时变功率谱模型,利用多重滤波技术和非线性最小二乘法拟合得到每条记录的Kameda模型参数值;通过分析模型参数随频率变化的散点图分布规律,建立了时变功率谱模型参数随频率变化的随机模型。采用随机振动理论和多元统计分析方法,分析了沿波传播方向距离、垂直于波传播方向距离及测点所在位置土层厚度等局部空间位置变化对时变功率谱模型参数的影响规律,探讨了时变功率谱模型参数的空间分布形式,建立了各模型参数随空间坐标变化的随机预测模型,从而为重大工程多点输入地震动参数的确定和多点输入加速度时程的合成提供实用模型。     

Rapidly installed temporary gauging for hurricane waves and surge,and application to Hurricane Gustav

Hurricanes can produce extreme nearshore waves and surge, but permanent gauging stations are often much sparser than is desired. This paper describes the rationale behind and outline for rapidly installed temporary coastal gauges, and presents results during Hurricane Gustav (2008). Within 48 h prior to landfall, twenty self-recording pressure gauges were deployed in depths of 1.4–23 m over more than 700 km of coastline, using helicopters to cover the large distances. Results showed a complex picture that was strongly dependent on location. East of the Mississippi Delta, open coast waves were large, and surge reached 3.8 m NAVD88 in marshes. West of the delta but near landfall, waves and surge were generally smaller as the river levees blocked flow from East to West. West of landfall, both waves and surge were very small and the most prominent feature was a water level drawdown that reached 1.5 m. Wave spectra varied strongly depending both on location and time from landfall.     

Study on elastic response of structures to near-fault ground motions through record decomposition

Accelerograms recorded near active faults have some important characteristics that make them different from those recorded in far-fault regions. High-frequency components in acceleration records and long-period velocity pulses are among notable specifications of such ground motions. In this paper, a moving average filtering with appropriate cut-off frequency has been used to decompose the near-fault ground motions into two components having different frequency contents: first, Pulse-Type Record (PTR) that possesses long-period pulses; second, the relatively high-frequency BackGround Record (BGR), which does not include large velocity pulses. Comparing the results with those extracted through wavelet analysis shows that moving average filter is an appropriate and efficient tool for near-fault records decomposition. The method is applied to decompose a suite of 91 selected near-fault records and the elastic response of structures is examined through their response to the decomposed parts. The results emphasizes that in contrast with ordinary far-fault earthquake records, response spectra of near-fault ground motions typically have two distinct local peaks, which are representatives of the high- and low-frequency components, i.e., BGR and PTR, respectively. Moreover, a threshold period is identified below which the response of structures is dominated by BGR while PTR controls the response of structures with periods longer than this period.     

A neural network based methodology to predict site-specific spectral acceleration values

A general neural network based methodology that has the potential to replace the computationally-intensive site-specific seismic analysis of structures is proposed in this paper. The basic framework of the methodology consists of a feed forward back propagation neural network algorithm with one hidden layer to represent the seismic potential of a region and soil amplification effects. The methodology is implemented and verified with parameters corresponding to Delhi city in India. For this purpose, strong g...     

土非线性参数变异性对标准设计谱的影响

岩土工程中存在许多不确定性,建筑物抗震规范设计中的标准设计谱实际代表着一种平均结果,并没有考虑到场地土体非线性参数的变异性。文中采用数值模拟的方法研究了土非线性参数变异性对标准设计谱的影响。给出了考虑土非线性参数变异性的概率设计谱。结果表明,土非线性参数变异性对标准设计谱的影响显著;粘性土和无粘性土的动剪切模量比对标准设计谱的影响决定于土非线性参数的概率水准,同时也取决于概率设计谱的频段;烈度7度、8度和9度下土体动剪切模量比变异性使标准设计谱平台最大变化50%、80%和100%,阻尼比变异性使标准设计谱平台最大变化40%、45%和60%。     

导向钻机液压管路的优化设计

导向钻机液压管路的尺寸直接影响着能量损失以及管路体积、质量的大小。采用优化设计方法,综合考虑能量损失及管路体积2方面的影响,建立了导向钻机吸油管路的目标函数,经编程求解,确定了管路的合理尺寸。