护坡工程空心螺母块立浇及安装施工技术研究与应用

空心螺母块因其外形简单,近年来在河湖生态护坡工程中被广泛应用。但护坡工程使用的空心螺母块数量较多,传统的平浇法预制,所需预制场地大且平整度要求高,螺母块运输安装费时费力、外观质量难以保证。文章针对护坡工程空心螺母块浇筑和安装的特点研究出一种操作简便、切实可行的连续立浇预制安装的施工方法,经过工程实际应用,有效保证了预制块的浇筑质量,提高了预制块的运输铺设效率,节约了预制场地的兴建面积。     

gain bounds for systems with sector bounded and slope‐restricted nonlinearities

This paper proposes a new method for calculating a bound on the gain of a system comprising a linear time invariant part and a static nonlinear part, which is odd, bounded, zero at zero and has a restriction on its slope. The nonlinear part is also assumed to be sector bounded, with the sector bound being (possibly) different from that implied by the slope restriction. The computation of the gain bound is found by solving a set of linear matrix inequalities, which arise from an integral quadratic constraint formulation of a multiplier problem involving both Zames‐Falb and Popov multipliers. Examples illustrate the effectiveness of the results, and comparisons are made against the state‐of‐the‐art. Copyright © 2011 John Wiley & Sons, Ltd.     

Decay rate of critical fluctuations in steam and in dilute steam-NaCl mixtures

The decay rate of critical fluctuations in steam and in a steam-NaCl mixture has been investigated experimentally with the aid of photon correlation spectroscopy. For pure steam, the measurements have been performed along seven isochores [(¦– _c¦)/_c<0.09] as a function of the temperatureT for (T–T_t)<1 K. The results have been compared with the values predicted by the renormalization-group theory written as a modification of the classical mode coupling theory. The agreement between experiment and theory is satisfactory along the critical isochore, but larger deviations are noted for _c when approching the transition temperatureT _t. The decay rate of a 0.1% (molar) dilute mixture of NaCl in H₂O has been measured along some near-critical isochores as a function of temperature. Its behavior, which is very different from that observed for pure steam, is dicussed.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

On the determination of the thermal diffusion factor from column measurements

A new method for experimental determination of the thermal diffusion factor _T for binary gas mixtures with a thermal diffusion column (TDC) is developed, based on A. M. Rozen's equation of TDC. The experimental results for _T are obtained in a reduced form in this approximation. An experimental reference point, determined in the same TDC with a standard gas mixture, is used for the transformation of the results for _T in absolute units. The proposed method is applicable for arbitrary gas mixtures, irrespective of the mass difference of the components.     

Viscosities of nonelectrolyte liquid mixtures. III. Selected binary and quaternary mixtures

This paper is the final in a series of three viscosity and density studies of pure n-alkanes and selected binary and quaternary mixtures. A standard U-tube viscometer was used for viscosity measurements, and a Pyrex flask-type pycnometer was used for density determinations. Results are given here for pure alkane and selected binary mixtures of n-tetradecane + n-octane, for selected quaternary mixtures of n-hexadecane + n-dodecane + n-decane + n-hexane, and for pure and selected quaternary mixtures of n-hexadecane + n-dodecane + n-nonane + n-heptane at 303.16 and 308.16 K. The principle of congruence was tested, as was the Grunberg and Nissan equation, as they have been shown to be useful as prediction techniques for other n-alkane binary mixtures. Comparisons were made between the two groups of quaternary alkane mixtures and the binary n-tetradecane + n-octane mixtures of the same pseudo composition to understand better the dependence of mixture viscosities on the composition parameter.     

Viscosity of binary mixtures. IV. Triethylamine with alkanes and monoalkylamines at 303.15 and 313.15 K

Viscosities and densities of seven binary mixtures of n-hexane, n-octane, isooctane, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine with triethylamine have been measured at 303.15 and 313.15 K. Deviations of viscosities from a linear dependence on the mole fraction and values of excess Gibbs energy of activation G ^*E of viscous flow are attributable to the H-bonding and to the size of the alkylamine and alkane molecules.     

西南山区交通工程弃渣的工程特性评价及其分类

山区交通工程弃渣力学参数的准确测定,一直是弃渣场边坡稳定性评价面临的基础科学问题。在山区交通工程弃渣场运行特点和弃渣固体废弃物特征认知的基础上,探讨弃渣取样和试验代表性问题的物理根源,依托实际工程累计数据尝试提出简单实用的弃渣工程特性评价和分类方法。结果表明:①常规交通工程弃渣的密度、颗粒分析和强度试验,由于弃渣的粒径范围差异大、颗粒空间分布不均、弃渣来源复杂等固体废弃物特征造成取样和试验代表性难题; 用多阶段坡角测量和颗粒分析试验代替传统的弃渣边坡试验,解决了试验和取样代表性难题。②利用弃渣粗细比可将弃渣分为细粒弃渣、混合型弃渣和粗粒弃渣。③根据弃渣粗细比、天然休止角和整形坡率,将西南山区交通工程弃渣分为细粒弃渣、混合型弃渣和粗粒弃渣等3类。细粒弃渣,弃渣粗细比小于0.3,天然休止角小于31.5°,整形坡率为1.00:2.00; 混合型弃渣,弃渣粗细比为0.3～1.0,天然休止角为31.5°～39.5°,整形坡率为1.00:2.00～1.00:1.50; 粗粒弃渣,弃渣粗细比大于1.0,天然休止角大于39.5°,整形坡率为1.00:1.50。④用多阶段坡角测量、颗粒分析试验和无黏性土边坡稳定性系数计算公式代替传统的弃渣边坡试验和稳定性系数计算方法,方法简单,结果保守,可以作为弃渣边坡稳定性评价和安全控制技术的有益补充。     

基于时间序列模式表示的异常检测算法*

提出了一种基于时间序列的模式表示提取时间序列异常值的异常检测算法(PREOV).时间序列的模式表示本身就具有压缩数据、保持时间序列基本形态的功能,并且具有一定的除噪能力.在时间序列模式表示的基础上提取异常值,可以大大提高算法的效率和准确性,达到事半功倍的效果.在本算法中,还使用了一定的剪枝策略,使得算法的时间复杂度进一步降低.该算法计算简单、实现方便、无须训练,可以支持时间序列的动态增长.     

边坡稳定性评价方法研究现状与发展趋势

随着岩土工程技术的进步与相关学科的发展,新的边坡稳定性分析方法不断涌现;另一方面,因对边坡工程地质条件缺乏足够的认识而评价方法选择不当导致工程事故时有发生。因此对边坡稳定性评价方法的原理、假设条件及适用范围进一步疏理很有必要。首先从评价方法的学科领域、基本原理、评价模型的假设条件等角度将其分为工程地质经验评价法、工程力学理论分析法、应用数学理论分析法、试验模拟法和现场监测与预测分析法等五大类。选择代表性的方法介绍每类评价方法的研究现状,指出存在的问题,分析与归纳各类评价方法的优缺点及其适用条件。最后对边坡稳定性研究及其评价方法的发展趋势进行展望。