Doing the first loop of planning for sustainable urban drainage system retrofits: A case study from Odense,Denmark

The planning and implementation of sustainable urban drainage systems (SUDS) requires intensive collaboration between professions and institutions. To improve the conditions for such practice in Denmark, the first loop of a SUDS-based retrofitting project was completed in Odense over a 6-month period. The project involved officials from the City of Odense and Odense Water Ltd., as well as university researchers. Studies of hydrological, environmental and socio-cultural aspects were developed by disciplinary teams and used to draft integrated solutions for two selected city districts. Albeit sewer surcharge was the initial catalyst, the main driver for the drafted solutions was urban planning. An assessment of the impact 1.5 years after completion indicated that the employed approach is valuable. In Odense, a planning procedure reflecting the loop process has become new practice. The project represents a key reference for the introduction of SUDS in Denmark.     

升温机制对膨胀型防火涂层隔热性能的影响

对水溶性(W型)和溶剂型(S型)这2种膨胀型钢结构防火涂层在ISO 834标准火及3条非标准火升温曲线下的隔热性能进行了试验研究,其中3条非标准火曲线的升温速率及最高温度均低于标准火.试验结束后对不同升温机制下防火涂层的膨胀倍率和膨胀层的泡孔结构进行定性对比分析,并根据隔热性能试验中温度的测量结果计算防火涂层的等效导热系数,用以对不同升温机制下防火涂层的隔热性能进行定量分析.分析结果表明:升温速率影响膨胀-固化阶段气体的逸出率,进而对防火涂层的膨胀倍率产生影响;升温速率不同,发泡剂分解释放气体的时间与熔融态涂层黏滞性的匹配度不同,炭层的泡孔尺寸不同;膨胀倍率越大,泡孔尺寸越小,炭层的隔热性能越好;与标准火下防火涂层的等效导热系数相比,非标准火下防火涂层的等效导热系数均有不同程度的提高,最大差异为65%(W型)和35%(S型);用标准火下膨胀型防火涂层隔热性能的检测结果来指导非标准火(火场温度和升温速率均比标准火低)下防火涂层的设计将导致不安全的结果.     

合理设计岩屑规程保证正常钻进条件——金刚石钻进技术专题之一

论述了正常钻进的条件，提出了合理岩屑规程是保证正常钻进的关键和设计钻头的主要依据之一，讨论了岩屑规程与金刚石钻头唇面工作状态、孔底表面粗糙度和岩屑粒度的关系，提出了相应的建议。     

地下水动态数值模拟中随机方法研究进展

地下水水流运动有很大的随机性,随机理论方法把地下水系统中的参数看成具有空间分布的随机场,可以对水流的不确定性和空间变异性进行模拟。该文介绍了地下水动态数值模拟中随机方法的原理、适用条件及存在的问题,重点讨论了国内外地下水动态随机模型的研究应用以及各种随机估参方法。文章还提出了此领域今后的发展方向,具有一定的借鉴意义。     

Code performance with improved two-group interfacial area concentration correlation for one-dimensional forced convective two-phase flow simulation

In gas–liquid two-phase flow simulation for reactor safety analysis, interfacial momentum transfer in two-fluid model plays an important role in predicting void fraction. Depending on flow conditions, a shape of the two-phase interface complicatedly evolves. One of the proposed approaches is to quantify the gas–liquid interface information using interfacial area transport equation. On the other hand, a more simplified and robust approach is to classify bubbles into two-groups based on their transport characteristics and utilize constitutive equations for interfacial area concentration for each group. In this paper, interfacial drag model based on the two-group interfacial area concentration correlations is implemented into system analysis code, and void fractions were calculated for the evaluation of numerical behaviors. The present analysis includes (1) comparison of one-group and two-group relative velocity models, (2) comparison with separate effect test database, (3) uncertainty evaluation of drag coefficient, (4) numerical stability assessment in flow regime transition, and (5) transient analysis for simulating the prototypic condition. Results showed that utilization of interfacial drag force term using constitutive equations of two-group interfacial area concentration yields satisfactory void fraction calculation results. The proposed solution technique is practical and advantageous in view of reducing the computational cost and simplifying the solution scheme.     

Investigation of fluidized bed behaviour using electrical capacitance tomography

The temporal and cross-sectional distributions of particles in a 127 mm diameter fluidized bed have been obtained using a new generation, high-speed electrical capacitance tomography. Two planes of eight electrodes were used and mounted at 160 and 660 mm from the gas distributor which was a 3 mm thick porous plastic plate (maximum pore size of 50-70 μ m). 3 mm diameter, nearly-spherical polyethylene granules made up the bed. Experiments at sampling frequencies of 200-2000 cross-sections per second and gas superficial velocities from just below the minimum fluidization to 83% above minimum fluidization velocities were used. The time series of the cross-sectional average void fractions have been examined both directly and in amplitude and frequency space. The last two used probability density functions and power spectral densities. The information gathered shows that the fluidized bed was operating in the slugging mode, which is not surprising given the size of the particles. It has been found that an increase in the excess gas velocity above the minimum fluidization velocity resulted in an increase in the mean void fraction, an increase in the length and velocity of the slug bubbles as well as the bed height, and a slight decrease in the slug frequency. The results are presented in a level of detail suitable for comparison with later numerical simulation.     

同位素测年新发展:81Kr测定古老地下水年龄理论

自从1966年Loosli&Oeschchger测定出大气中的81Kr,就已经有人设想放射性81Kr(半衰期为(2.29±0.11)×105年)可能成为测定古老地下水年龄(105~106年)的有效工具。但一直没有付诸实践,直到2000年,Collon等人首次利用81Kr同位素确定澳大利亚大自流盆地(GAB)的古老地下水年龄。本篇文章中主要介绍了影响81Kr同位素测年的因素,81Kr的取样制样分析过程,回旋加速质谱仪分析81Kr同位素的原理。     

基于特色培养的水利工程类专业教学改革探析

以扬州大学水文与水资源工程专业人才培养,以及该专业目前的办学定位和培养规格分析为基础,从明确专业培养目标与任务、加强教学体系建设、注重实践教学环节、完善核心课程与主干课程体系设计、构建学科专业交叉融合机制、注重人才队伍培养与学科建设,以及完善教育质量评估与保障措施等方面探讨了以特色培养为导向的水文专业教学改革措施。     

往复运动下圆凹坑形表面织构减摩性能研究

为研究圆凹坑形表面织构在往复运动下的减摩性能,尤其是织构面积率对摩擦因数和润滑状态的影响,在UMT-Ⅲ型摩擦试验机上进行往复式摩擦试验.试验中采用的摩擦副材料为Cr12与45#钢,在45#钢上加工出面积率为2％、6％、10％的圆凹坑形织构.保持运动频率不变,在不同载荷下试验,研究织构面积率在不同载荷下的减摩性能;然后改变往复运动频率,在固定载荷下试验,采用频率参数作为速度参数计算动压参数,绘制Stribeck曲线,研究织构面积率对润滑状态的影响.结果表明:当载荷较小时,较大面积率的表面织构减摩效果较好,当载荷较大时,表面织构具有增大摩擦力的作用,即表面织构的减摩效果对载荷敏感;在较小的载荷下,面积率较大的表面织构可以在较低的运动频率下进入流体润滑状态.     

基于激光电磁超声的裂纹检测研究

为检测内裂纹,建立了一套基于脉冲激光激发、电磁超声探头接收的非接触型超声检测系统。为避免在试件表面产生烧蚀损伤,采用热弹性模式激发超声,采用EMAT探头接收信号。利用出平面EMAT探头和内平面EMAT探头,分别研究了横波与纵波在半圆铝制试块的传播情况。最后,结合阴影法,使用该试验系统测量了试件背面的裂纹,检测得到的裂纹深度与实际深度非常接近。证明在热弹性模式下,激光激发、EMAT探头接收信号的方法对于内裂纹的检测是可行的。