考虑底部隆起的浅埋隧道围岩压力计算分析

针对浅埋隧道开挖后底部隆起变形现象,应用极限分析上限法构造了考虑底部隆起变形的围岩压力计算模型,结合线性Mohr-Coulomb准则等推导出极限围岩压力的理论表达式。通过约束条件将围岩压力的计算转化为数学中的最优化问题,编制程序进行了优化计算。将计算结果与工程实测数据及文献计算结果进行了对比,验证了当前方法的可靠性。同时,指出在运用极限分析法处理浅埋隧道围岩压力问题过程中应将隧道底部一同考虑,对隧道底部支护会对整个围岩压力产生影响,有助于隧道结构的整体稳定。研究可以为浅埋隧道的开挖、支护提供一定的理论指导.     

评价矿井突水危险性的关键层方法

将煤层底板至含水层间承载能力最大的一层岩层看作起阻水作用的关键岩层（简称关键层），并把它简化为薄板，利用板的理论解确定该岩层的破断跨距，用以评价底板突水的危险性．实例分析表明，这种预测突水危险性的方法是简明有效的．     

钢框架中组合楼盖的面内变形

为了研究影响钢-混凝土组合框架中组合楼盖隔板性能的因素,以楼板厚度、框架侧移刚度以及结构平面刚度布置为参数对钢框架中的组合楼盖进行了弹性有限元分析．分析结果表明,除长宽比外,组合楼盖的隔板性能还与其面内刚度以及支撑体系的特性有关．根据分析结果提出了组合楼盖隔板性能的评价方法, 并与试验结果进行了验证．该方法可以为工程实践中评价组合楼盖的隔板性能作参考．     

Effects of timber skidding on chemical characteristics of herbaceous cover, forest floor and topsoil on skidroad in an oak (Quercus petrea L.) forest

This paper examines the effects of timber harvesting by skidding on some soil properties (sand, silt, clay, pH, organic carbon, bulk density and compaction), herbaceous cover (unit mass) and forest floor (unit weight) properties. Also N (%), P, K, Na, Ca, Mg, Fe, Zn, Cu and Mn (ppm) were determined in all herbaceous cover, forest floor and two soil depth (0–5 cm and 5–10 cm) on skidroad of an oak (Quercus petrea L.) stand in Istanbul Belgrad Forest – Turkey. In this study, obtained results are; the forest floor and the herbaceous cover amount on the skidroad have been found considerably lower than undisturbed area. There were some crucial changes in the characteristics of the soil which has been investigated down to 10 cm depth. Soil bulk density was found quite high in the samples taken from the skidroad subject to compaction compared to the ones on the undisturbed area. Nevertheless, no important difference had been detected between the skidroad and the undisturbed area at both soil depths in terms of organic carbon contents. Moreover, the soil acidity (pH) values showed noteworthy differences in the analysis of soil samples taken from both soil depths on the skidroad and on the undisturbed area. Fe and Cu contents of herbaceous samples on skidroad were significantly higher than undisturbed area. Forest floor on skidroad had significantly higher K content, and significantly lower Zn, Mn and N content compared to undisturbed area. P, Fe, Zn and Mn contents were found significantly lower in 0–5 cm soil depth on skidroad than undisturbed area. In 5–10 cm soil depth, concentrations of N, P, Fe, Zn and Mn were significantly lower, while Mg and Cu contents were significantly higher than undisturbed area. Results indicate that long-term harvest using skidding techniques on these sites had adversely affected soil cation concentrations, physical soil conditions and mass of herbaceous cover and forest floor.     

Pricing caps with HJM models: The benefits of humped volatility

In this paper we compare different multifactor HJM models with humped volatility structures, to each other and to models with strictly decreasing volatility. All the models are estimated on Euribor and swap rates panel data maximizing the quasi-likelihood function obtained from the Kalman filter. We develop the analysis in two steps: first we study the in-sample properties of the estimated models, then we test the pricing performance on caps. We find the humped volatility specification to greatly improve the model estimation and to provide sufficiently accurate cap prices, although the models has been calibrated on interest rates data and not on cap prices. Moreover, we find the two-factor humped volatility model to outperform the three-factor models in pricing caps.     

Flexural reinforcement of concrete floor slabs by carbon fiber textiles

The effect of carbon fiber textile for flexural reinforcement to deteriorated reinforced concrete floor slab is tested in laboratory by cutting out six specimens from existing structure aged more than 70 years. The repair method between concrete and carbon fiber textile is used as experimental parameter. From the test results, deformation, bond characteristic of carbon fiber textile and the applicability of carbon fiber textiles to flexural reinforcement of floor slabs are discussed.     

室内低温地板辐射采暖的温度分布及湍流流动数值模拟

采用k-ε模型和壁面函数法耦合辐射模型对低温地板辐射采暖房间进行了数值模拟,通过分析室内温度分布特征及流动特性,得出了室内空气温度分布随室内高度的变化关系、围护结构表面温度及热流的分布特性,数值结果表明了在室内主流区域空气温度分布均匀,其温差在1℃左右,从而说明了低温地板辐射采暖舒适性的原因,数值模拟结果也表明了辐射在地板采暖中的重要性,辐射热流达到了总热流的50%-60%。     

低温地板辐射采暖系统的传热分析与仿真

建立了低温地板辐射供暖系统的传热过程的数学模型,用有限元法对数学模型进行求解。以一个动态仿真程序得出了不同供回水平均温度和排管间距下的地板表面最高温度和单位面积的热流量,阐明了系统的舒适和节能特性,为工程设计提供了理论依据。     

基于动态地场和元胞自动机的自行车流建模

针对现有自行车流模型对车辆间作用考虑不足的问题,在原多车道元胞自动机模型的基础上引入动态地场,在模型中纳入了排斥力,并充分考虑了前车速度对后车行驶的影响,体现了自行车的灵活性等特征,提出了换道成本的概念并建立了新的基于比较交通环境的换道规则. 数值仿真结果表明：1）该模型能更准确地描述自行车流,反映自行车流的特征,得到的数据符合实际;2）单位车道宽度的通行能力随着车道数的增加有小幅下降;3）激进的驾驶风格使得换道次数大幅增加,通行能力下降. 关键词： 自行车流 元胞自动机 动态地场 仿真     

Evaluation of a bioluminescence method, contact angle measurements and topography for testing the cleanability of plastic surfaces under laboratory conditions

Detection of adenosine triphosphate (ATP) by bioluminescence is used, for instance, in the food industry and in hospitals to assess the hygiene status of surfaces. The aim of this laboratory study was to investigate the feasibility of the ATP method for estimating the cleanability of resilient floor coverings from biological soil. The surfaces were worn using a Soiling and Wearing Drum Tester, and soiled and cleaned with an Erichsen Washability and Scrubbing Resistance Tester. In the laboratory test carried out with the bioluminescence method, most of the new and worn floor coverings that were biologically soiled were cleaned efficiently. According to this study, the semiquantitative ATP screening method can be used for hygiene monitoring of flooring materials. No correlation was found between cleanability and contact angles or surface topography measured using a profilometer. However, by revealing local irregularities and damage on surfaces, scanning electron micrographs appeared useful in explaining differences in cleanability.