循环流化床烟气脱硫塔入口结构改进的数值模拟

采用商用Fluent软件提供的k-ε湍流模型对循环流化床脱硫塔内部流场进行了数值模拟,重点考察入口结构对脱硫塔内气相速度分布均匀性的影响,并用速度不均匀度定量描述了流场的均匀性。结果表明,当前使用90°弯管进气结构的脱硫塔内部流场存在明显的不均匀性,主要是入口处气流90°转向造成的。为此采用组合弯管进气结构代替90°弯管进气结构,以改善脱硫塔内流场不均匀性。入口结构改为组合弯管进气结构后,脱硫塔内流场不均匀性得到很大改善,速度分布的不均匀度明显减小,因此组合弯管进气结构有利于烟气与脱硫剂的充分混合反应,提高脱硫效率。     

Design parameters for solar light pipes in the Brazilian context

In Brazil, there are few studies investigating the performance and guidelines parameters of solar light pipes from the national perspective. This paper aims to analyse the performance of a solar light pipe prototype installed in a test house in the city of Curitiba/PR, Brazil and to indicate a set of parameters for the design of solar light pipes for the Brazilian social housing context. The performance of a solar light pipe provided with different lighting devices to control and redirect light was analysed. The best performance for diffusers was obtained during partially covered skies. Light redirection devices presented the best efficiency during clear sky conditions with direct sunlight, on working-planes closer to the prototype. The developed prototype with the lighting control devices produced a considerably enhanced lighting performance, complementing natural lighting in indoor environment. Based on the results, recommendations and guidelines to enhance solar light pipe configurations are proposed.     

自生动态膜-生物反应器结构优化的研究

针对自生动态膜-生物反应器内部结构进行了动力学运行的理论分析,通过能量平衡机理对自生动态膜-生物反应器体系进行了讨论,基于体系总能耗最小的原理推导出液相循环流动方程.建立的混合液流速与清水流速之间的关系模型可以很好地反映混合液流速与清水流速之间的关系.通过建立的清水流速测定方法得出反应器结构与清水膜面错流流速之间的关系：调整降流区横截面积(A_d)与底部通道截面积(A_b)的比值为0.7以及升流区横截面积(A_r)与顶部通道截面积(A_u)的比值为0.9,调整降流区横截面积与升流区横截面积的比值在1.2～1.5范围内以及增加反应器的有效高度H_D都可以在不改变曝气强度的条件下增加膜面错流速度,此结果与推导出的循环流动方程可以很好地吻合.     

Passive convergence-permeable reactive barrier (PC-PRB): An effective configuration to enhance hydraulic performance

● A novel PRB configuration based on passive convergent flow effect was proposed. ● A 2D finite-difference hydrodynamic model, PRB-Flow, was developed. ● PC-PRB can significantly enhance the hydraulic capture capacity of PRB. ● The PRB geometric dimensions and materials cost are effectively reduced. ● The dominant influential factor of the PC-PRB capture width is pipe length, L_p. A novel permeable reactive barrier (PRB) configuration, the so-called passive convergence-permeable reactive barrier (PC-PRB), is proposed to overcome several shortcomings of traditional PRB configurations, such as high dependency to site hydrogeological characteristics and plume size. The PC-PRB is designed to make the plume converge towards the PRB due to the passive hydraulic decompression-convergent flow effect. The corresponding passive groundwater convergence (PC) system is deployed upstream of the PRB system, which consists of passive wells, water pipes, and a buffer layer. A two-dimensional (2D) finite-difference hydrodynamic code, entitled PRB-Flow, is developed to examine the hydraulic performance parameters (i.e., capture width (W) and residence time (t)) of PC-PRB. It is proved that the horizontal 2D capture width (W_h) and vertical 2D capture depth (W_v) of the PC-PRB remarkably increase compared to that of the continuous reactive barrier (C-PRB). The aforementioned relative growth values in order are greater than 50% and 25% in this case study. Therefore, the PRB geometric dimensions as well as the materials cost required for the same plume treatment lessens. The sensitivity analysis reveals that the dominant factors influencing the hydraulic performance of the PC-PRB are the water pipe length (L_p), PRB length (L_PRB), passive well height (H_w), and PRB height (H_PRB). The discrepancy between the W_h of PC-PRB and that of the C-PRB (i.e., ΔW_h) has a low correlation with PRB parameters and mainly depends on L_p, which could dramatically simplify the PC-PRB design procedure. Generally, the proposed PC-PRB exhibits an effective PRB configuration to enhance hydraulic performance.     

Using a social learning configuration to increase Vietnamese smallholder farmers’ adaptive capacity to respond to climate change

Social learning is crucial for local smallholder farmers in developing countries to improve their adaptive capacity and to adapt to the current and projected impacts of climate change. While it is widely acknowledged that social learning is a necessary condition for adaptation, few studies have systematically investigated under which conditions particular forms of social learning are most successful in improving adaptive capacity of the most vulnerable groups. This study aims to design, implement and evaluate a social learning configuration in a coastal community in Vietnam. We make use of various methods during four workshop-based interventions with local smallholder farmers: interviews with key farmers and commune leaders, farmer-to-farmer learning, participatory observations and focus group discussions. The methods for evaluation of social learning configuration include in-depth interviews, focus group discussions and structured survey interviews. Our findings show that the social learning configuration used in this study leads to an increased problem ownership, an enhanced knowledge-base with regard to climate change impacts and production adaptation options, improved ability to see connections and interdependencies and finally, strengthened relationships and social cohesion. The results suggest that increased social learning in the community leads to increase in adaptive capacity of smallholder farmers and improves both their economic and environmental sustainability. We discuss the key lessons for designing learning configurations that can successfully enhance adaptive capacity and smallholder farmers’ agency and responsiveness to the challenges posed by climate change impacts.     

城市道路隔离带绿化模式对人行道空气质量的影响评价

探讨城市道路绿化隔离带对于污染物的阻滞效应,以减少城市道路污染向两侧横向扩散,保护道路行人免受来自机动车道污染物的伤害具有重要的现实意义.因此,本研究在太原市区选择16条主干道(28个监测样点),以4种绿化植物配置模式(乔木+灌木+低绿篱、乔木+低绿篱、乔木、低绿篱)为研究对象,在无风或者微风(风速小于2 m·s-1)条件下对SO2、NOx、TSP和PM10等5种污染物进行现场监测.研究结果表明,城市道路绿化隔离带对于控制机动车道的主要污染物向非机动车道的扩散具有明显作用,绿化隔离带的植物模式差异会影响绿化带吸附和阻隔污染物能力的强弱.在此基础上,通过构建一个新的评价指标来比较各个模式在阻滞污染物方面的能力.结果显示,与其他模式相比,低绿篱模式和乔木+灌木+低绿篱模式分别对NH3和PM10具有更高的降低能力.对于SO2、NH3、NOx等气态污染物,以乔木(T)为配置模式的绿化带效果最佳,而对于TSP、PM10等颗粒污染物,乔木+灌木+低绿篱(TSH)模式的阻滞净效应最高.新评价指标能够准确定量评价绿化带植物对污染物阻滞效应能力的大小,具有较好的应用性.     

电除尘器反电晕现象的模拟试验研究

研究了电除尘过程中的反电晕现象及其对ESP工作的影响，对现有抑制反电晕的措施进行了分析总结，提出了使用合理的极配方式来减弱反电晕的影响，以期能促进ESP在收集高比电阻粉尘方面的应用。     

机器人精确轨迹控制方法的研究

研究了一种六关节机器人通过奇异位形时新型解的方法。当机器人接近奇异位形时 ,操作空间内微小的运动 ,会引起关节速度趋向无穷大 ,导致机器人失去控制。该方法应用线几何理论和反螺旋理论 ,识别出机器人线性相关的关节轴线和操作空间的不可行运动。通过对相应Jacobian矩阵的行和列进行重新整合 ,使机器人在奇异点时 ,工作空间可行运动与关节运动仍保持一一对应关系 ,从而得到机器人的精确轨迹控制。最后 ,使用上述方法 ,对PUMA机器人作了实例分析 ,结果证明了该方法的有效性     

运用系统原理提升装备技术状态管理监督效能研究

为解决装备技术状态管理控制质量不高、效率低下等问题,全面提高某装备领域技术状态管理水平,运用系统原理的理论,从军方管理与监督角度,识别了装备技术状态管理监督系统的特征,从系统的要素、结构、功能、运行与环境等方面,对装备技术状态管理监督系统特性进行了深入分析。指出偏离系统目标影响系统功能发挥、管理体制与运行机制不协调、运行规则制定缺乏系统考虑以及系统没有主动适应环境变化等四个方面,是造成装备技术状态管理控制效果不好、执行效率不高等问题的主要原因。提出了应坚持系统目标的引领作用、坚持系统结构与运行合理匹配、坚持系统功能一体化协调和坚持系统综合适应环境变化等四个方面建议。     

普通旋风除尘器结构尺寸优化设计

以Ｌｅｉｔｈ设计法为基础，考虑除尘效率和压降等因素的影响，以除尘效率为理想目标，以一些流体力学特性和实际限制、经验值为约束，建立数学模型，用数学规划论的方法进行旋风除尘器结构尺寸的优化，以此设计的旋风除尘器应用到现场既可节约投资，又可降低能耗，设计方法通用性好．