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991.
An electrochemical mass spectrometry technique was developed based on a homemade analytical device for sequential analysis of the heavy metals with various speciations in the scales. Four speciations(e.g., water-soluble speciation, organic speciation, indissoluble speciation and elemental speciation) of heavy metals are sequentially extracted by H2O, CH3OH, EDTA-2Na and electrolysis for online electrospray ionization mass spectrometry(ESI-MS) detection. The method takes significant advantages, such as requiring no tedious offline sample pretreatment, high speed of analysis(20 min), high throughput (multi-metals), good sensitivity(0.5 μg/L) and rich chemical information(four speciations). As a result, the rapid comprehensive characterization of four speciations of Pb, Ni, Cu, Zn, Fe, Ba, Mn, Cr and Ca in water pipe scales has been qualitatively achieved. It demonstrated that the present method is a powerful tool for the effective assessment of potential hazards in drinking water, which provides a new analytical idea for evaluating water quality. 相似文献
992.
Javier Gmez-Gmez Rafael Carmona-Cabezas Elena Snchez-Lpez Eduardo Gutirrez de Rav Francisco Jos Jimnez-Hornero 《Entropy (Basel, Switzerland)》2021,23(2)
The last decades have been successively warmer at the Earth’s surface. An increasing interest in climate variability is appearing, and many research works have investigated the main effects on different climate variables. Some of them apply complex networks approaches to explore the spatial relation between distinct grid points or stations. In this work, the authors investigate whether topological properties change over several years. To this aim, we explore the application of the horizontal visibility graph (HVG) approach which maps a time series into a complex network. Data used in this study include a 60-year period of daily mean temperature anomalies in several stations over the Iberian Peninsula (Spain). Average degree, degree distribution exponent, and global clustering coefficient were analyzed. Interestingly, results show that they agree on a lack of significant trends, unlike annual mean values of anomalies, which present a characteristic upward trend. The main conclusions obtained are that complex networks structures and nonlinear features, such as weak correlations, appear not to be affected by rising temperatures derived from global climate conditions. Furthermore, different locations present a similar behavior and the intrinsic nature of these signals seems to be well described by network parameters. 相似文献
993.
A set of simplified boundary conditions for a flexible beam connected to a rigid body at one end and free at the other end is presented and applied to the case of a fluid-conveying, fluid-immersed pipe. These boundary conditions represent an analytically tractable approximation to those of a submersible which uses a combination of jet action and flutter instability induced tail motion to produce thrust. The boundary conditions are made non-dimensional, and the effect of the non-dimensional mass of the rigid body on system stability is assessed. The neutral stability of this system is determined within a two-parameter space consisting of the velocity of the fluid within the tail, and the forward speed of the submersible. Equations in the literature, derived using slender-body theory, were used to compute the sign of the thrust produced by the tail and the tail's Froude efficiency for the neutrally stable waveforms of the beam. 相似文献
994.
构造了一类步数为2(k+1)的次黎曼流形,给出其上连接原点和t轴上一点测地线的条数和相应测地线的长度,同时得到其中最短的测地线. 相似文献
995.
A strategy for the systematic design of polymeric superlattices with tailor‐made mini‐bandgaps and carrier mini‐effective masses is described and computationally implemented by means of an envelope crystalline‐orbital method, which is a straightforward adaptation for molecules of the envelope‐function approximation widely used in solid‐state physics. Such strategy relies on the construction of π‐conjugated periodic block copolymers from well‐characterized parent polymers, in such a way that the aforementioned electronic parameters can be predicted from the lengths of the blocks. Illustrative calculations for prototypical (PPPx‐PDAy)n superlattices demonstrate the plausibility of the strategy and the advantages of the computational implementation used. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2532–2540, 2010 相似文献
996.
本文提出了一种新的基于水平衰减全反射-傅里叶变换红外光谱(HATR-FTIR)的小波特征提取与反向传播人工神经网络模式分类方法以提高FTIR对早期大鼠结肠癌的诊断准确率.对60只DMH诱导的SD大鼠,44只诱导鼠的第二代鼠,36只正常SD大鼠的结肠正常组织、异常增生、早癌及进展期癌组织所获得的的HATR-FTIR,利用连续小波多尺度分析法提取12个特征量,采用反向传播人工神经网络进行分类,识别准确率分别为100%、94%、97.5%及100%.实验结果表明此方法对早期结肠癌具有较高的诊断率. 相似文献
997.
In this paper a class of polynomial interior-point algorithms for horizontal linear complementarity problem based on a new parametric kernel function, with parameters p[0,1] and σ≥1, are presented. The proposed parametric kernel function is not exponentially convex and also not strongly convex like the usual kernel functions, and has a finite value at the boundary of the feasible region. It is used both for determining the search directions and for measuring the distance between the given iterate and the μ-center for the algorithm. The currently best known iteration bounds for the algorithm with large- and small-update methods are derived, namely, and , respectively, which reduce the gap between the practical behavior of the algorithms and their theoretical performance results. Numerical tests demonstrate the behavior of the algorithms for different results of the parameters p,σ and θ. 相似文献
998.
Summary: A novel accelerated fracture mechanics extrapolation procedure based on cyclic test with cracked round bar (CRB) specimens was verified by a correlation of real pipe failure time to simulated failure times at a temperature of 60 °C. The procedure was applied to predict the long-term failure of modern PE 80 and PE 100 pipes 23 °C. Moreover, the used stress intensity factor concept also allows to consider the impact of arbitrary additional loading situations like soil loads or point loads and to assess pipe lifetime under complex loading situations. 相似文献
999.
针对测量船传统实时水平测量方法精度较低(≥10.0″)的问题,引入了基于光学测量手段的动态实时船体水平姿态测量方法。采用"光学编码精密测角+惯性同步复示平台+水平误差检测工具"的设计模式,保证了跟踪的稳定性,提高了测量精度。实验结果表明:提出的方法可以提供比传统惯导系统更稳定、精度更高(纵摇5.37″,横摇3.60″)的船体水平姿态数据;可以作为一种普遍适用的运动载体精密水平测量监测手段,为运动载体实时提供高精度的水平基准信息,或用于运动载体惯导水平精度鉴定等。 相似文献
1000.