Analytical approach on magnetohydrodynamic Casson fluid flow past a stretching sheet via Adomian decomposition method

Flow phenomena of three-dimensional conducting Casson fluid through a stretching sheet are proposed in the present investigation with the impact of the magnetic parameter in a permeable medium. The adaptation of particular transformations is useful to modify the governing equations into their nondimensional as well as the ordinary form. However, these transformed equations are nonlinear and approximate analytical methods for the solution of the complex form of governing equations. In particular, the Adomian decomposition method is proposed for the solution. The behavior of several variables, such as the magnetic and porous matrix, on the flow profile as well as the rate of shear stress, are discussed via graphs and tables. The conformity of the current result with the earlier study shows a road map for further investigation. The major concluding remarks are; the retardation in the velocity distribution is rendered due to an increase in the Casson parameter moreover, the Casson parameter favors in reducing the rate of shear stress coefficient in magnitude.     

Data quality and uncertainty assessment methodology for pavement LCA

In performing pavement life cycle assessment (LCA), users are facing various reports of energy intensity coefficient (EIC) of pavement materials which differ considerably among data sources and therefore alter the LCA results significantly. Instead of selecting a certain EIC without or of little explanation for the current pavement LCA practices, this study proposed a methodology to build probability density function (PDF) for EIC based on available data-set and their qualities. Each data was first evaluated about the data quality indicator (DQI) through data quality pedigree matrix and converted to PDF in modified Beta distribution form. Three weighting methods, the DQI one, coefficient of variation (COV) one and analytical hierarchy process (AHP) one, were developed to assign weightings for different data. Monte Carlo simulation was run with the weighted PDF of each data as input to obtain the ultimate PDF for EIC. A case study to estimate the bitumen’s EIC with eight data samples were performed using the proposed methodology. It is found (1): the estimates by the proposed methodology is of higher reliability (lower COV) compared to any single data due to utilisation of information of the overall data samples; (2) the AHP weighting method is most favoured despite the results of the three weighting methods are close; (3) the central estimates of bitumen’s EIC are between5.4~5.8 MJ/kg. The proposed methodology is helpful in aiding calculating EICs for pavement materials and capturing uncertainties in LCA results in a statistical sense.     

The effects of porosity,asphalt content and fiberglass incorporation on the tensile strength and resilient modulus of asphalt concrete blends

Asphalt concrete is the prevailing material used for road surface construction. Its adequate characteristics in providing stability, durability and driving safety are controlled by complex interactions between its components. Thus, it is important to estimate the sensitivity of asphalt concrete mechanical properties as a function of its volumetrics. For this study, different combinations between asphalt content (3.5, 5 and 7.5%) and porosity values (above 4%) were used in order to disassociate these properties. The influence of mixing in fiberglass (0.5%) was also analyzed. It was found that porosity is significantly more relevant than the asphalt content in the prediction of tensile strength and resilient modulus of fiber-free asphalt concretes. In fiber-reinforced mixtures, the mechanical properties are improved by increasing the asphalt content, which suggests a better bonding between fibers and aggregates. For both cases, decreasing porosity is beneficial. By grouping both sets of results, it was possible to create a unique theoretical curve for both the tensile strength (q_t) and the resilient modulus (RM). The RM/q_t ratio was 5800 for the fiber-free group, and 3900 for the fiber-reinforced group - suggesting a better fatigue life indicator for asphalt concretes when fibers are added.     

TRIZ创新方法剖析路面渗水仪底座和路面的密封性能

针对路面渗水仪底座和路面的密封性能不良问题，运用TRIZ创新方法的因果链、技术矛盾、物理矛盾、进化分析等工具找到原因，获得解决方案。通过调研及试用，不断优化及调整所选方案，达到最优解决效果。应用效果证明TRIZ理论有助于创新并快速解决工程实际问题。     

贵州省干线公路沥青路面典型病害研究

"十二五"期间,随着贵州省交通建设的飞速发展,干线公路的里程及施工质量也迅速提高。但同时,干线公路沥青路面出现了许多早期病害,并且病害种类也更加多样化。本文对贵州省9个地市的干线公路沥青路面进行了系统调查,并就路面典型病害的成因进行了分析。     

Direct high-purity hydrogen production from ammonia by using a membrane reactor combining V-10mol%Fe hydrogen permeable alloy membrane with Ru/Cs2O/Pr6O11 ammonia decomposition catalyst

The hydrogen production capabilities of the membrane reactor combining V-10 mol%Fe hydrogen permeable alloy membrane with Ru/Cs₂O/Pr₆O₁₁ ammonia decomposition catalyst are studied. The ammonia conversion is improved by 1.7 times compared to the Ru/Cs₂O/Pr₆O₁₁ catalyst alone by removing the produced hydrogen through the V-10mol%Fe alloy membrane during the ammonia decomposition. 79% of the hydrogen atoms contained in the ammonia gas are extracted directly as high-purity hydrogen gas. Both the Ru/Cs₂O/Pr₆O₁₁ catalyst and the V-10 mol% Fe alloy membrane are highly durable, and the initial performance of the hydrogen separation rate lasts for more than 3000 h. The produced hydrogen gas conforms to ISO 14687–2:2019 Grade D for fuel cell vehicles because the ammonia and nitrogen concentrations are less than 0.1 ppm and 100 ppm, respectively.     

Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked.     

软岩与水相互作用研究综述

软岩是一类松散、破碎、软弱及风化膨胀性的强度较低的岩石,在水环境作用下软岩易产生大变形失稳破坏。大多数岩土工程事故都涉及到软岩与水的相互作用,研究软岩与水相互作用对于分析某些由软岩失稳引起的工程事故具有重要的理论和现实意义。针对软岩与水相互作用这一问题,从软岩与水相互作用的分类、软岩吸水特性的影响因素及其软岩吸水失稳机理等方面,对国内外具有代表性的研究成果进行了梳理。结果表明:软岩与水相互作用可分为力学作用、物理作用和化学作用。在各种影响软岩吸水特性的因素中,主要因素是黏土矿物的含量和种类、孔隙结构,其他影响因素有水压变化、软岩的干湿循环次数、软岩的块体尺度(尺度效应)和吸水时间等。软岩吸水失稳的根本原因是吸水后黏土矿物微观结构发生变化,而是否含蒙脱石等吸水性极强的黏土矿物并非直接原因;后者只是对软岩吸水过程起到促进作用。     

海藻酸钙固定化零价铁抗团聚及堵塞的作用机制

以海藻酸钠（SA）、氯化钙、微米零价铁（MZVI）为原料，制备了海藻酸钙（CA）固定化MZVI填料（CAZ），通过静态烧杯实验和动态PRB模型实验，探讨了CA运用对Cr(Ⅵ)的去除性能的影响，并通过电镜扫描分析了CA避免团聚、堵塞机制。实验结果表明，CA凝胶颗粒的运用能显著提升MZVI的除Cr(Ⅵ)性能，CAZ相比MZVI对Cr(Ⅵ)的去除率和反应速率分别提升7.1倍、23.0倍；MZVI利用率的提高是CAZ反应器处理Cr(Ⅵ)水量显著大于MZVI反应器的主要原因，MZVI反应速率的提高是CAZ反应器出水Cr(Ⅵ)浓度显著低于MZVI反应器的主要原因。电镜扫描结果表明，SA与氯化钙交联形成的CA具有丰富的骨架孔道结构，具有骨架支撑作用，能有效克服MZVI颗粒因重力作用导致团聚、降低比表面积的缺陷。CA表层固定的MZVI颗粒与Cr(Ⅵ)反应生成的(Fe_xCr_1-x)(OH)₃ 络合沉淀会冲破CA表层外壳，释放到零价铁-渗透反应墙（Fe⁰-PRB）系统中，导致PRB反应初期出现堵塞现象；大部分MZVI颗粒被固定在CA内部，CA内部有较多孔隙结构，这些孔隙结构会控制(Fe_xCr_1-x)(OH)₃ 络合沉淀释放，从而缓解了Fe⁰-PRB后期长期运行持续堵塞的问题。     

河流护岸多孔生态材料对水体中硝态氮去除试验

为进一步提升护岸材料对面源污染物的净化能力,采用骨料交联法制备了具有较高透水率的多孔生态砌块,研究骨料粒径与砌块透水率的关系,并采用动水挂膜法对不同透水率的生态砌块进行反硝化细菌表面负载,在此基础上,研究所制备的不同骨料粒径的生态砌块的透水率、比表面积等对水体中硝态氮去除率的耦合效应。结果表明:在相同孔隙率条件下生态砌块的透水率随比表面积的增加而降低,且随着骨料粒径的增大而提高;生态砌块对水体中硝态氮的去除率随透水率的增加呈现先增大再减小的趋势,其中骨料粒径为7~11 mm,透水率为6.6 m L/(s.cm~2)的多孔生态砌块对硝态氮的去除率可达90.3%。