基于仿生技术的高强度复合材料的研究进展

自然界造物的方式是人们制备高强度复合材料的榜样,自然材料的优异特性可以归结为长期自然进化和自然选择条件下所形成多尺度的多级组装结构。阐述了目前研究较多的仿生技术的特点,挖掘了这几类仿生材料的主要组成成分和多级结构实现高强度的机制,重点论述四大类仿生高强度复合材料:基于植物的仿生复合材料、基于动物的仿生复合材料、基于细菌的仿生复合材料、基于天然矿石的仿生复合材料的制备过程和增强机制的研究;揭示了通过仿生手段实现复合材料高强度的原理,并指出其应用领域和目前研究中存在的问题。     

Analysis of synergy degree and its influencing factors in hydropower EPC project management

The use of engineering procurement construction (EPC) mode is currently a trend in hydropower engineering construction. The clarification of the internal relationship between hydropower EPC projects and the realization of synergy has great significance in improving management efficiency and implementation effect. In this work, a three-dimensional system and a system model of hydropower EPC project management synergy are constructed. The mechanism and factors that influence the degree of management synergy are analyzed on the basis of management synergy theory. Furthermore, the evaluation index system and the degree of synergy model are established, and grey relational analysis is utilized to identify the key factors that affect the synergy degree. Thus, this study aims to facilitate the hydropower EPC project management synergy, provide a quantitative method for synergy degree evaluation, and propose corresponding promotion strategies. Results show that the order degree of each subsystem presents a steady upward trend. Specifically, the order degree of the subsystem at the trial operation stage is low, which is the major restriction on the further improvement of the synergy degree of EPC project management. The key factors in improving the synergy level of hydropower EPC project management are mainly concentrated in the information and organization synergy subsystems, including the construction degree of information platform, the performance of functions, the timeliness of information transfer, and the functions of the information platform.     

基于场协同理论的冷藏展示柜内流体对流换热分析

目的研究冷藏柜内对流换热机理,增强冷藏柜内流体对流换热效果,提高冷气流冷却效率。方法从冷藏柜出风口角度出发,建立数学模型,通过Ansys流体分析软件对冷藏柜内流场进行模拟仿真,应用场协同理论研究冷藏柜内流体流动及传热机理。结果出风口角度在30°附近时冷藏柜内换热效率较高且温度分布较为均匀,此时商品壁面的存在改变了冷气流流动方向。在壁面增加半圆突起后,气流沿圆弧切线方向流动,改善了速度与温度梯度之间的协同程度,从速度场、温度场及其相互作用的角度增强了冷藏柜内的对流换热效果,整体换热效率提高了38.65%。结论冷藏柜内流体流动及传热强化的根本在于流体的扰动,而出风口角度的改变和壁面凸起的存在加强了商品对流体的扰动,两者共同作用改变了冷藏柜内场的分布,进而提高了冷藏柜整体的冷藏效率,该研究可为冷藏柜的工厂化生产提供参考价值。     

多向协同布孔法爆破拆除深基坑支撑梁的应用

随着城市建设的快速发展,地下空间的高效利用受到广泛关注,而深基坑钢筋混凝土支撑梁的安全、高效拆除是工程建设的关键环节。为此,提出一种沿支撑梁轴向、垂直向同时预制炮孔的多向协同布孔技术及其装药方法,并将其应用于某深基坑支撑梁爆破拆除项目。应用结果表明,在传统垂直向布孔方式基础上,同时布置轴向弧形炮孔;借助牵引装置在轴向孔内敷设导爆索,采用空气间隔装药结构并进行分区延时爆破,可有效降低爆破危害效应,提高爆破作业安全性与拆除效率,改善爆破拆除效果,研究成果可为类似爆破拆除工程提供借鉴。     

Ross LPD型静态混合器内湍流传热与混合强化特性

在湍流状态Re=2640~17600下,采用恒热通量传热实验与数值模拟相结合的方法,系统研究Reynolds数Re和交错角对Ross LPD型静态混合器内湍流流动与传热性能影响,采用Nusselt数、Darcy摩擦系数、综合传热系数、速度场与温度梯度和压力梯度协同角等参数评价混合器内传热强化性能;基于CFD与LPT相耦合分析混合器内流体微元拉伸率。研究结果表明：SST k-ω模型预测Ross型静态混合器湍流阻力及传热结果与实验结果具有很好一致性;Ross混合器流场内形成与流场尺度较为接近的纵向涡,其涡心在圆形截面与半圆形截面中心间周期性迁移,横截面内湍流分散混合效率是Kenics的3.36~1.72倍;当Re>7040时,Ross LPD综合传热性能明显优于KSM;当叶片夹角为30°时,综合传热性能系数具有最大值;Ross LPD内插件具有高效低阻的技术优势和结构改进潜力。     

Photocatalytic partial oxidation of methylpyridine isomers on TiO2 particles under an anaerobic condition

Photocatalytic oxidation of methylpyridine isomers (2-methylpyridine, 3-methylpyridine, and 4-methylpyridine) was investigated in a mixed solution of acetonitrile and water or acetonitrile using various kinds of TiO₂ powders as photocatalysts. The main products from methylpyridine isomers were pyridinecarboxaldehyde isomers (2-pyridinecarboxaldehyde, 3-pyridinecarboxaldehyde, and 4-pyridinecarboxaldehyde). Rutile large TiO₂ particles showed the highest level of activity for oxidation of 2-methylpyridine probably because band bending was necessary for the oxidation of 2-methylpyridine. On the other hand, a fine particle having an anatase or rutile phase showed a higher level of activity than large TiO₂ particles for oxidation of 3-methylpyridine. A rutile fine particle showed the highest level of activity for the reaction. It was found that pure rutile or pure anatase particles were inactive for oxidation of 4-mathylpyridine. If the particles are not extremely small, pure rutile and pure anatase powders show fairly high levels of activity, and those containing both anatase and rutile phases show the highest level of activity. The activity of pure rutile particles was also enhanced by physically mixing them with a small amount of small anatase particles, which were inactive for this reaction. These results can be explained by the synergism between rutile and anatase particles. All of these reactions effectively proceeded even under anaerobic conditions. Photocatalytic reduction of methylpyridine isomers concomitantly proceeded on TiO₂ particles under the conditions used. These results suggest that the activities of TiO₂ photocatalysts for oxidation of methylpyridine isomers are dominated by the oxidation potential of alkylpiridine and band bending of TiO₂ particles.     

Numerical simulation of heat transfer of latent functionally thermal fluid in tubes with coaxially inserted cylindrical bars in laminar

The heat transfer of latent functionally thermal fluid in three kinds of tubes with coaxially inserted cylindrical bars is numerically researched using equivalent specific heat model, and the flow fields are analyzed with field synergy field. It is found that in the tubes with coaxially inserted cylindrical bars, the heat transfer effects of functionally thermal fluid become more and more pronounced with the Ste decreasing. This is similar to be case of functionally thermal fluid flowing in smooth straight tubes. Compared with the results receiving from smooth straight tubes, the heat transfer of functional thermal fluid in tubes with coaxially inserted cylindrical bars has been significantly enhanced. And this effect becomes more apparent as the diameter of coaxially inserted cylindrical bars increases meanwhile, however, energy consuming of the tubes shows the same trend. Supported by the Key Project of National Natural Science Foundation of China (Grant No. 50436020)     

高效除尘除雾器在超低排放中应用的技术经济分析

脱硫系统协同除尘技术路线在最大限度利用现有设备的前提下,实现烟尘超低排放。通过对三级屋脊式除雾器、管式除尘除雾装置及冷凝式除尘除雾装置技术比较可知,三级屋脊式除雾器运行稳定、成熟可靠、应用广泛。同等改造条件下三级屋脊式除雾器改造费用低于其他两种除尘除雾装置。     

基于PERE区域协同发展的城市成长——简论南京城市成长中的几个主要问题

PERE区域协同是城市成长的基础和实现手段,是健康、顺利,快速发展的前提条件,是建设和谐社会的客观要求。PERE区域协同发展不是即生的,它是通过对原有区域不断调整、评价,周而复始逐步实现的。本文在分析区域协同发展的基础上,从基于PERE系统的区域协同的视角对城市成长的内涵、动因进行了重新阐释并提出了相关建议。     

水平管外沸腾强化换热的数值模拟与场协同分析

应用FLUENT软件对制冷剂R134a在光管和横纹槽管水平管外沸腾传热进行三维数值模拟,得到其饱和泡状沸腾过程中体积含气率的分布规律,并比较它们的换热系数。结果表明横纹槽管外侧能够很好地强化沸腾传热。此外,还通过改变边界条件分析质量流量、热流密度的变化对横纹槽管管外沸腾换热系数的影响。最后应用场协同理论,从局部换热角度分析其强化机制。研究表明,横纹槽管水平管外沸腾换热得到强化的原因是其凹槽前后的速度场与温度梯度场之间夹角较小,协同程度更好。