苏州古城区绿道构建策略与分析

随着社会经济的不断发展古城苏州面临着来自旅游、交通等多方面的压力与日俱增,对绿道的需求也不断增加,相对密织的传统街巷为苏州古城绿道建设提供了得天独厚的条件,但同时古城区局促街巷空间与现代出行和旅游需求之间的矛盾日显突出,传统街巷的文化与特点也逐渐丢失。本文从苏州古城区现状与问题入手,结合苏州古城区水陆双棋盘等地方特色分析及古城区绿道线路选择影响因素分析,提出构建苏州古城区绿道系统设想与策略。     

溶气气浮-炭砂过滤工艺处理低温低浊水质试验研究

采用溶气气浮-炭砂过滤工艺处理北方某原水水质,通过对工艺各项参数进行优化,优选聚合氯化铝铁为最佳混凝剂,其最佳投药量为5 mg/L（以Al^3＋计）,气浮单元最优回流比为10%,适合炭砂滤柱的进水负荷为8 m^3/（m^2·h）。该工艺长期运行结果表明,在低温低浊进水条件下,溶气气浮-炭砂过滤工艺对浊度、CODMn、UV254、TOC的平均去除率分别达到99%,60%,55%和45%,出水水质可达到《生活饮用水卫生标准》（GB 5749—2006）中的限值要求。     

基于零相位误差滤波的局部放电故障识别

开关柜局部放电放电信号中混有较大的噪声信号,传统的有限冲激响应(finite impulse response,FIR)滤波方法会造成滤波后信号相位的偏移,从而影响以功率谱为特征量的故障识别的正确率。针对这种情况,提出了基于零相位误差滤波方法的局部放电故障识别方法。首先,通过高速电流互感器采集局部放电信号。然后,采用零相位误差滤波(zero phase error filtering,ZPEF)滤除放电信号中的噪声。其次,通过FFT变换分析放电信号的功率谱,取1.0~1.5 MHz和2.5~3.0 MHz 2个频段的功率谱构造故特征向量。最后,采用最小二乘支持向量机对局部放电信号进行故障识别。实验结果表明,采用ZPEF可以提高局部放电故障的识别率。由此也得出一个推论:在确保相同的故障识别率的情况下,采用ZPEF可以提高故障的识别速度。     

Experimental study on shear mechanism of reinforced concrete beams with stirrups

为研究钢筋混凝土有腹筋梁的受剪机理，以剪跨比、混凝土强度等级、配箍率为变量，完成了集中荷载作用下16根钢筋混凝土简支梁受剪性能试验。为了避免过高的纵筋配筋率，采用HRB600级钢筋作为纵向受拉钢筋。通过在箍筋内部开槽预埋电阻应变片测量箍筋的应变，分别得到钢筋混凝土有腹筋梁中混凝土和箍筋承担的剪力。试验结果表明：剪跨比和混凝土强度等级对混凝土和箍筋分担的剪力在总剪力中所占比例有显著影响，且二者呈相反的变化趋势；当剪跨比较小时，配箍能提升混凝土的受剪承载力，但箍筋本身承担的剪力较小，箍筋甚至不能屈服;当剪跨比较大时，斜裂缝倾角小于45°，实际与裂缝相交的箍筋数量多于按45°计算的数量，箍筋承担的剪力增大。与无腹筋梁相比，大剪跨比（剪跨比为3）有腹筋梁中混凝土承担的剪力减小。在试验研究的基础上，收集了国内外369根有腹筋梁受剪承载力的试验数据，采用统计分析方法得到了有腹筋梁受剪承载力计算公式，其较GB 50010—2010《混凝土结构设计规范》计算公式更加合理，计算结果也偏于安全。     

刚性路面板模型试验研究

针对工程中水泥混凝土路面板足尺试验难度较大的问题 ,提出采用相似理论进行刚性路面板的荷载和应力的试验研究方法 ,探讨混凝土路面板研究中相关基础理论问题。通过对 9块不同相似比的刚性路面板的试验研究 ,得到了几何尺寸相似的弹性地基板在静载作用下 ,力学性能相似的初步结论。     

Creep deformation mechanism of magnesium-based alloys

Two heat-resistant magnesium alloys AJC421 and Mg-2Nd were prepared. Both as-cast Mg-2Nd and AJC421 alloys exhibited good creep resistance in comparison with commonly used magnesium alloys. The improvement in creep properties through Nd addition to pure magnesium is attributed to both solid solution and precipitation hardening. The stress exponents of 4.5–5.5 and activation energies of 70.0–96.0 kJ/mol obtained from the as-cast Mg-2Nd alloy at low temperatures and low stresses indicate the five power law can be used for predicting the creep mechanism. The additions of alkaline earth elements Sr and Ca into Mg–Al alloys suppress the discontinuous precipitation of Mg₁₇Al₁₂ and form thermal-stable intermediate phases at grain boundaries, leading to effective restriction to grain boundary sliding and migration. However, the mechanism responsible for creep deformation of Mg–Al based alloys with Ca and Sr additions is not consistent with the results of microstructure observations performed on the alloys before and after creep tests.     

Spline-Discretization-Based Free Vibration Analysis for Orthotropic Plates

Extensive numerical analysis indicates that the conventional spline functions semidiscretization analysis for orthotropic plates and shells reported by Li et al. (Journal of Engineering Mechanics, 2003) cannot be directly employed in the vibration analysis of orthotropic rectangular plates with the free (F) and/or guided (G) edges. The modified spline function based method then is presented in this paper to cope with the vibration analysis of isotropic and orthotropic rectangular plates with possible combinations of the free (F), simply supported (S), clamped (C), and guided (G) edges at the four bounds. Through dividing the rectangular plate into N and M equal subintervals along the x and y directions, the modified spline functions consisting of N+3 and M+3 local B3 spline functions with respect to N+1 points and two extended additional points in the x direction and M+1 points and two extended additional points in the y direction, in which the first and last three local B3 spline functions have been modified for accommodating to any one of the F, S, C, and G boundary conditions, are used as the displacement trial functions. Employing the modified spline functions, only one unknown coefficient is required to be determined for the deflection and its first and second derivatives, respectively, at a certain bound. The modified spline function matrix based characteristic equation of the orthothopic rectangular plate is derived using its potential energy functional. In comparison to the finite-element method and the spline finite strip method (SFSM), the present method has remarkably fewer numbers of degrees of freedom, and thus it is computatively more efficient. Likewise, the computational program with minimal preparation of input data can be easily developed through the present formulation. The results indicate that the present method can render both very high accuracy and fast convergence.     

盐析—树脂吸附法处理D-对羟基苯甘氨酸生产废水

采用盐析-树脂NDA-99吸附组合工艺处理D-对羟基苯甘氨酸生产过程中排放的高浓度含酚废水.实验确定的最佳工艺条件:(1)盐析剂为无水Na2SO4,其投加质量浓度为140 g/L,温度40℃,搅拌时间30 min;(2)采用双柱串联吸附,吸附流量10 ml/h,处理水量150 mL/批次.实验结果表明:在最佳工艺条件下对该废水进行处理,出水无色透明,CODCr挥发酚、TOC去除率分别为41.31B～98%、61.28%～64.07%、39.09%～40.46%.     

中国电解金属锰产业成本分析

从电解金属锰的成本构成出发,介绍了目前国内锰矿的资源现状和市场情况,分析了电力、硫酸、二氧化硒对电解金属锰成本的影响。从选矿、还原、制粉和电解等工艺方面展望了电解金属锰的新技术、新工艺的发展方向,对全面把握行业的发展趋势有一定的借鉴意义。     

氧化应激在糖代谢紊乱中的作用

为探讨氧化应激和糖尿病发生／发展的相互关系,由四氧嘧啶诱导建立糖尿病大鼠模型,进行抗氧化干预。动物经此化学诱导剂处理后,血糖／血脂和硫代巴比妥酸反应产物升高,ＳＯＤ降低,再经抗氧化干预,即可发生逆转恢复。试验结果表明糖／脂代谢调节和氧化应激密切相关。