Oxygen permeation properties and surface modification of acceptor-doped CeO2/MnFe2O4 composites

The preparation and oxygen permeation properties of the (Ce_0.8Pr_0.2)O_2−δ − x vol% MnFe₂O₄ composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce_0.8Pr_0.2O_2−δ, an oxygen flux density of 6 μmol⋅cm⁻²⋅s⁻¹ (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000^∘C. Unlike composites consisting of Gd-doped CeO₂ and MnFe₂O₄, the oxygen permeability of the (Ce_0.8Pr_0.2)O_2−δ – x vol% MnFe₂O₄ composites was almost constant regardless of the volume fraction of MnFe₂O₄; however, the optimum volume fraction of MnFe₂O₄ was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere. In addition, the surface modification of the (Ce_0.8Gd_0.2)O_2−δ – 15 vol% MnFe₂O₄ composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm² on the both side of the 0.3 mm-thick (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm⁻²⋅s⁻¹ in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by a large pO₂ gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition of the LB film.     

模袋混凝土在寒区江河堤防护岸工程中的应用

阐述了模袋混凝土护岸工程的设计与施工方法，通过与混凝土预制板护坡的比较，表明模袋混凝土护坡优于混凝土预制板护坡，有推广应用价值。     

高压定喷在堤防险工的应用

阐述了高压定喷在堤防险工中的应用。探讨了施工期的质量控制及质量检查方法。     

圆柱齿轮优化设计的数学模型变换

采用复合形法对直齿圆柱齿轮传动进行了优化设计，并采用数学模型变换的方法使迭代次数减少，收敛速度增快，从而易于求解成功。设计结果表明，可以明显地减轻圆柱齿轮的重量。     

齐齐哈尔市城市防洪堤险工弱段成险因素分析

在论述堤体、堤基岩性组成的基础上，对险工弱段成险因素进行了分析，提出预防和消险措施。     

浅议堤防的维护与度汛抢险措施

介绍了堤防的过量沉降、裂缝的处理方法，在汛期防止堤防漫顶、防风浪及工程实践中防滑坡的处理措施。     

河道整治工程中的平行作业

河道整治工程各分部工程间的平行作业,对缩短工期,节省投资具有十分重要的意义.文章利用先建工程作后续工程的施工临时建筑物使用,并科学安排各作业面的施工程序和进行技术上的可行性论证,是完全合理的,建议推荐.     

反渗透系统最低透盐率的全微分法元件位置优化

分析了反渗透膜元件3项测试指标的离散性,提出了系统流程中不同测试指标膜元件安装位置优化的概念,描述了膜元件位置优化的全微分计算方法,明确了全微分法元件位置优化对于降低系统透盐率的有效性,并验证了全微分法元件位置优化方案对给水温度等运行参数变化的稳定性。     

梧州市平浪防洪堤总体设计方案选择

介绍了梧州市平浪防洪堤堤线、堤型的选择原则、思路,总体设计方案等基本情况。该设计方案融入可持续发展及生态水利的理念,将环保、人文以及可持续发展等贯彻于设计的全过程,体现了人与自然的和谐共处。     

Hydrodynamic behaviour of a new permeable pavement material under high rainfall conditions

Permeable pavements are among the most effective alternative solutions for sustainable stormwater management. They decrease impervious surfaces in urban areas, reduce the risk of flooding under high rainfall conditions and protect the natural environment against stormwater pollution. In a view to ensuring sustainable stormwater management, a new eco-material has been designed for producing permeable pavements. This material is a mixture of construction wastes (crushed concrete) and organic matter (compost). The crushed concrete is the structural support and the compost is used for retention and the biological treatment of stormwater pollution. The purpose of the research work presented in this paper was to evaluate the hydrodynamic behaviour of a new permeable pavement material under high rainfall conditions. The experimental approach adopted for this research study is a temporal moment analysis. Therefore, for the experimental study, we simulated high rainfall with a return period of 10 years (Torreilles in 2001, France). The rainfall data were provided by Meteo France. The rainfall was maintained at an intensity of 126 mm/h, corresponding to a flow rate of 16 l/h at laboratory apparatus scale. Then, the flow rate was increased three times, to 25 l/h, 50 l/h and finally 100 l/h to subject the material to extreme conditions.