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.     

Radiation induced decontamination of Cr(Ⅵ), Cu(Ⅱ) and phenol in some tannery effluents

Industrialization has led to a number of environmental problems, such as release of toxic metals and other toxic organic and inorganic compounds to the environment. Among all, the rapid expansion of leather related industries in Pakistan have resulted in considerable environmental problems and effluents from processing of both domestic and imported hides and skins have increased pollution to alarming levels. Some tannery effluents of Peshawar area investigated in the present study showed high concentrations of Cr(Ⅵ) (2.7-12.6 mg/L), Cu(Ⅱ) (2.6-11.4 mg/L) and phenol (0.1-4.2 mg/L). These contaminants are very toxic and must be removed from effluents before releasing into water bodies. A new technique of gamma irradiation has been investigated to decrease the load of COD and concentrations of Cr(Ⅵ), Cu(Ⅱ) and phenol associated with tannery effluents to the permitted values. It was observed that concentration of Cr(Ⅵ) in the effluents can be brought to the permitted level by applying radiation dose of 3 kGy. A radiation dose of 2.5 kGy was required to remove more than 95% of Cu(Ⅱ) and 100 % degradation of phenol in tannery effluents could be achieved by only one kGy of radiation dose.     

浮阀塔板气液相界面积

研究了浮阀塔板上的气液接触状况以及相界面积。同时根据湍流液体中气泡变形与破碎的机理,建立了计算浮阀塔板相界面积的理论模型。该模型可用于比较不同浮阀结构对相界面积的影响。在理论研究的基础上,设计了一种新型浮阀——导向菱形浮阀。通过实验证明该浮阀塔板的相界面积得到显著提高。     

崩落采矿形成冰碛补给型泥石流相似模拟试验

崩落采矿法形成的冰碛补给型泥石流作为发育在高寒山区的特殊地质灾害类型,给矿山的安全高效开采造成了严重影响.为研究崩落空间发展过程与泥石流之间的关系,开展了相似模拟试验,模拟降雨条件下崩落采矿法的放矿过程,研究矿石、冰碛物、水等3种因素对泥石流形成的影响,结果表明:随着放矿的进行,矿石中混有地表冰碛物的量越来越多,放出的...     

浅谈城市住宅小区景观绿化工程项目管理

通过对上海浦东盛世年华住宅小区景观绿化管理的切身体验,探讨如何搞好住宅小区景观绿化管理.     

京津地区人口增长与分布的时空间演化分析

在Arcgis9.0地理信息系统的支持下,采用普通克立格插值和反距离加权插值两种方法研究京津地区人口的分布规律,结果表明:在主城区点效应和主干道交通的廊道效应作用下,该区的人口分布趋势是以北京和天津的中心城区为高密度人口聚集区域,并沿主要交通动脉由中心向周围地区呈梯度递减变化,在两城市间沿京津交通廊道形成了一个人口持续增长和密集分布的廊道区域。近几年该区域的中心城区人口密度逐渐减少,城市外围区人口增加,人口郊区化发展迅速。     

煤炭自燃标志性气体预测指标的实验研究

设计并研制了氧化热解实验模拟装置,通过对峰峰矿区小屯矿工作面采空区煤样的氧化热解模拟实验,绘制了各氧化热解气体CO2、O2、C2H6和CO等气体浓度随温度的变化曲线,并对其分析找出了该矿采空区煤炭自燃的标志性气体预测指标,从而为掌握工作面采空区煤炭自燃的规律和制定有效合理的煤炭自燃发火的防治措施提供依据,为煤矿的高效生产提供安全保障。     

功能混合住区功能构成比例量化研究 ——以天津市为例

在注重布局合理、和谐宜居的新型城镇化理念下,功能混合住区能够避免单一功能住区带来的生活不便、职住 分离、空间割据、环境污染等城市问题,也能更好的顺应城市发展和居民日常生活的需要。通过对天津市24 个功能 混合住区样本的实地调研与统计学研究,探索了功能混合住区功能构成比例的一般规律。结果表明：功能混合住区中 居住功能所占比例约为50%~70%,非居住功能约为30%-50%。并以此提出建议与讨论,对当前国内功能混合住区 的规范制定及开发建设提供借鉴与参考。     

三峡库区木鱼包滑坡不同库水升降速率变形响应离心模型试验研究

本文采用地表位移监测和离心机模型试验研究了木鱼包滑坡在不同库水升降速率条件下的变形响应规律,取得以下认识:(1)木鱼包滑坡在重力和库水等因素作用下,促滑段不断挤压抗滑段而发生推移式蠕滑变形.(2)木鱼包滑坡变形主要受库水位高程和升降速率影响,降雨对滑坡的变形影响有限.165 ～ 175 m水位时,较高的库水上升速率才能...     

浅析混凝土结构中的钢筋代换

钢筋代换是混凝土结构施工中经常遇到的问题,本文介绍了钢筋代换的几种原则,根据(CB50010 -2002)《混凝土结构设计规范》,并结合工程实例分析影响钢筋代换的主要因素,提出在钢筋代换中应注意的几个问题。