Construction Effect on Load Transfer along Bored Piles

The load transfer behavior along bored piles is affected by details of pile construction particularly those imposing stress and moisture changes to the surrounding soils. An investigation involving moisture migration tests, in situ horizontal stress measurements, and borehole shear and pressuremeter tests shows clear effects of construction that lead to subsequent changes in soil properties. The construction of bored piles in Singapore and the region often involves casting of concrete either in unsupported “dry” boreholes or in “wet” boreholes filled with water. It is necessary to differentiate these two extreme construction conditions in bored pile design. Based on triaxial compression and pressuremeter tests on the residual soil of the Jurong Formation in Singapore, the variation of soil modulus with shear strain can be described by a hyperbolic function. A procedure is recommended for assessing the combined effect of stress relief and soaking on soil modulus by introducing a modulus reduction factor. Modulus degradation curves from pressuremeter tests with the borehole conditions properly simulated are found capable of producing load transfer curves that are comparable to those deduced in the field.     

用scanf()函数输入浮点数出现问题的解决办法

本文讨论了用scanf()函数输入浮点数出现的问题,并分析了该问题产生的原因,最后文章重点给出了针对这类问题的4种解决方案。     

Morphologies and Properties of Micro-Arc Oxidation on Plate and Cylinder 2024 Al Alloy

Samples with two different shapes of 2024 aluminum alloy were treated with micro-arc oxidation (MAO), and the formation process and mechanism of oxidation film was analyzed. The results show that different geometrical curvature of the material has an influence upon the uniformity of films and the corrosion-resistance.     

Lanthanum Distribution and Oxygen Vacancy Concentration in SrBi4-x Lax Ti4O15

The Raman and X-ray photoemission spectroscopy of lanthanum-doped SrBi4Ti4O15 (SBLT -x, x =0.00, 0. 05, 0. 10, 0. 25, 0.50, 0. 75 and 1.00) ferroelectric ceramics were investigated to explore the La substitution site and the influence of La-doping on the oxygen vacancy concentration. The results suggest that La3 ions behave pronounced site selectivity for the A site in the case of x ≤ 0.10, and they are incorporated into Bi2O2 layers at higher content. The oxygen vacancy concentration declines with La-doping, and the decrease seems saturated as La content is higher than 0.10.     

Connectivity oriented fast Hough transform for tool wear monitoring

Tool wear monitoring can be achieved by analyzing the texture of machined surfaces. In this paper, we present the new connectivity oriented fast Hough transform, which easily detects all line segments in binary edge images of textures of machined surfaces. The features extracted from line segments are found to be highly correlated to the level of tool wear. A multilayer perceptron neural network is applied to estimate the flank wear in various machining processes. Our experiments show that this Hough transform based approach is effective in analyzing the quality of machined surfaces and could be used to monitor tool wear. A performance analysis of our Hough transform is also provided.     

300MW汽轮发电机组径向可倾瓦轴承性能研究

本文详细分析了热弹变形对轴承性能的影响，结果表明热变形对轴承性能的影响较小，而热弹变形对轴承性能的影响较大。     

弧齿锥齿轮铣齿机切削系统时序辨识

为了提高弧齿轮加工精度和切齿效率，提出弧齿锥齿轮铣齿机切削系统的时序分时建模系统辨识方法，通过对Y2250型铣齿机工件主轴垂直和水平方向的振动测试，应用研制开发的时间序列分时建模程序包，得出该机床固定安装法的切削系统模型，并进行了模态分析及时序谱分析。噪声方差很小，辨识结果具有较高的可信度。     

Symmetry in electron diffractions from helical structures

In this work, we elucidate the regular rule of the symmetry in electron diffraction patterns from helical structures. It is affected by the value of the dominating Bessel function orders for the layer lines and relative orientation of the samples with respect to the electron beam. For Single-Walled Carbon nanotubes (SWCNTs), we use analytic analysis and computer simulations to demonstrate that the 2mm symmetry of the electron diffraction may break down not only from an achiral SWCNT, but also from a chiral SWCNT. Also, the simulation work for B-DNA is presented to corroborate the theoretical analysis.     

用混沌优化方法进行平面四杆机构的函数发生器综合

利用混沌运动的遍历性、内在随机性、“规律性”等特点，结合MATLAB5．3．1高级程序设计语言的优化工具箱，提出了一种混沌约束优化算法。运用该算法编写了MATLAB程序，对平面四杆机构的函数发生器综合问题进行了研究，从而找到了实现最大精确点时该问题的全部解，为实际机构的设计提供了多种选择方案。