城市地下管网建设要综合统筹

在城市的基础设施中,地下管线在最大程度上保证了城市的正常运转。在我国飞速发展的背景及城镇化进程逐渐加快的背景下,由于各种管网建设管理不善而发生了诸多的问题,本文主要研究的是城市地下管网建设的综合统筹。     

浅析市政道路工程施工质量问题及防治措施

随着我国市场经济体制的不断完善,市政道路作为经济发展的关键基础设施日益发挥着重要的作用。市政道路工程的施工是复杂的经济技术活动,涉及社会主体和自然因素。基于此,本文研究了市政道路施工质量问题及防治措施。     

采煤工作面局部风流雾化降温效果分析

为分析低温雾化喷淋对高温采煤工作面局部风流的降温效果,采用Eulerian-Lagrangian二相流描述方法,通过液滴与湿空气的双向耦合作用,对高温风流的降温效果进行了数值计算,计算结果表明：1次降温后,风流温度约有4℃的急剧降低,1排喷嘴的有效作用距离为10 m,10 m后,风流温度又逐渐升高1.5℃,总体上,回采面风流的温度呈现出阶跃性的上升趋势;拟合得到的风流降温效果随喷嘴流量呈负指数变化;液滴喷射角在70°~90°范围时,降温效果较明显,而细水雾的高压雾化喷嘴能明显提高降温效果。     

吐温-85对冷轧钢在盐酸溶液中的缓蚀性能

用失重法研究了吐温-85(聚氧乙烯山梨醇三油酸酯)对冷轧钢在盐酸溶液中的缓蚀作用,详细考察了缓蚀剂质量浓度(10～100mg/L)、温度(20～50℃)、腐蚀浸泡时间(6～144h)和盐酸浓度(1.0～8.0mol/L)对缓蚀性能的影响.结果表明:吐温-85对冷轧钢在1.0mol/L HCl溶液中具有良好的缓蚀作用,缓蚀率随缓蚀剂质量浓度的增加而增大,但随温度和盐酸浓度的增加而减小.通过Arrhenius公式和Mathur经验动力学公式分别求出了相应的腐蚀动力学参数(表观活化能Ea, 指前因子A,速率常数k, 动力学常数B),并根据这些参数讨论了吐温-85的缓蚀行为.     

室温脱钴对PCD微观结构及力学性能的影响

为提高PCD使用过程中的热稳定性,选用硫酸-过氧化氢混合溶液在室温下对PCD进行脱钴处理,研究其脱钴机理及脱钴对PCD微观结构及力学性能的影响。通过SEM观察到PCD在室温脱钴48 h后表面出现较大深度的腐蚀坑,钴相基本被去除,上下表面脱钴深度分别为176 μm和162 μm;通过EDS可确定脱钴层剩余钴的质量分数为0.93%,而未脱钴层钴的质量分数为7.64%,表明87.83%的钴在实验中被硫酸-过氧化氢混合溶液溶解而去除。对PCD样品进行残余应力测量,脱钴之前的残余压应力为483.91 MPa,脱钴之后的残余压应力为330.35 MPa,后者相对前者减少31.73%,说明脱钴可以有效降低PCD内部残余压应力。      

基于动态规划的电池储能系统削峰填谷实时优化

削峰填谷是电池储能系统的基本功能之一。为了更好地发挥储能系统作用、延长电池使用寿命,削峰填谷优化需综合考虑电池容量和充放电次数、变流器出力、实时负荷曲线、与储能系统其他控制功能相配合等因素。文中提出一种基于动态规划的实时修正优化控制策略,可在优化模型中引入充放电次数限制和放电深度限制等非连续约束条件,并通过将电池电量离散化等方法解决含有非连续约束的优化问题。同时,针对电网扰动等因素引起的储能系统其他控制功能动作导致的电池可用容量不确定变化,通过在线修正的方法加以解决。上述控制算法已成功应用于南方电网兆瓦级锂离子电池储能示范工程。以该系统所在的深圳碧岭站负荷实测数据为基础,对所设计控制策略进行了验证,说明了其良好的优化效果。     

我国电站燃煤锅炉CO_2排放状况及减排措施

我国燃煤发电的CO2年排放量逐年增加,同时CO2年减排量也逐年提高,因此CO2排放强度逐年降低。统计表明,1949～2010年我国燃煤发电累计CO2排放量约397.79亿t,CO2减排量约6.437亿t,占CO2排放量的1.62%。目前,燃煤发电CO2排放强度已由原来的3 301g/(kW.h)降到973g/(kW.h),下降了70.52%;对应GDP产值的CO2排放强度从8.091t/万元降到0.835t/万元,下降了89.68%。建议推行发电企业竞价上网,进一步降低CO2排放强度。     

Interface-based crystal particle autoselection via membrane crystallization: From scaling to process control

Accurate crystallization control is an essential aspect for chemical engineering and separation processes. Herein, we demonstrated the novelty of membrane crystallization (MCr) on the interfacial based-crystal particle autoselection aimed for nucleation regulation and process control. With the proposed model based on a van der Waals-friction-hydrodynamic force field and classical nucleation theory, the motion mechanisms of heterogeneously induced nucleation were illustrated. The defined particle detachment criterion K revealed the control mechanism of the crystal particle motion behavior: temporary adherence, detachment, and perpetual adherence (scaling) at the membrane interface. For the first time, the function region of MCr (nucleation detection, scaling control, and crystallization regulation) was systematically illustrated and validated with the directly observed laboratory demonstration. These findings also demonstrate the potential applications of the uniform size distribution, morphology modified particle manufacture, and in situ nucleation detection. © 2018 American Institute of Chemical Engineers AIChE J, 65: 723–733, 2019     

Germination improves the functional properties of soybean and enhances soymilk quality

The effects of soybean variety and germination time on structural changes, antinutritional factor content, antioxidant activity of germinated soybean, and on the functional properties of soymilk were comprehensively investigated. The results showed that the antioxidant activity increased with increasing germination time. The content of antinutritional factors decreased with increasing germination time. Soybean varieties with the lowest tannin and trypsin inhibitor content were DN690 and HJ1. Lipoxygenase activity and phytic acid content showed no significant differences among soybean varieties. The content of α-helices and β-turns in soybean protein decreased with increasing germination time, while the content of β-sheets was increased. Soybean protein was progressively broken down into smaller molecular peptides during the germination process. The digestion and content of soluble protein in soymilk increased with germination. In summary, we show that germination is an effective, cheap, and green method that improves the functional properties of soybean and soymilk.