冲击回波信号的波形结构特征提取及分类研究

针对典型的非均质材料混凝土内部缺陷大小无损检测这一难题,利用人的听觉系统的生理学和心理学的研究成果,基于ＥＩＨ模型建立了进行时域波形结构特征提取的方法,并用结构自适应模糊聚类神经网络对提取的特征进行了分类试验,结果表明该特征提取方法能较好地解决从冲击反射时域信号来进行肃离缺陷大小识别问题。     

生态混凝土的研究现状与展望

生态混凝土是一种新型的生态建筑材料，具有广阔的应用前景。介绍了生态混凝土的概念、分类以及国内外研究、应用现状，并指出了生态混凝土的意义及其发展趋势。     

植被生态混凝土制备工艺研究进展

介绍了植被生态混凝土的定义及分类,以及这类混凝土的应用现状;通过总结前人针对制备方法的研究成果,包括配比设计、搅拌、成型、养护等步骤,提出了各个工艺需要掌握的关键因素;阐述了定量化衡量植被生态混凝土制备性能指标,并基于此性能指标讨论了影响因素与检测方法;阐明了植被型生态混凝土今后的发展方向。     

生态混凝土的应用研究及存在问题

生态混凝土具有良好的环境协调性而逐渐被重视和应用于透水混凝土、植被混凝土和净水混凝土等方面,在综述生态混凝土设计施工、强度与耐久性、碱环境的改善与透水性能的保持的基础上,根据生态混凝土的结构和性能特点提出其配合比设计方法、碱环境与耐久性改善、孔隙性质保持的研究思路.     

浅谈混凝土耐久性

混凝土的耐久性是指混凝土在实际使用条件下抵抗各种破坏因素的作用,长期保持强度和外观完整性的能力。影响结构耐久性的因素很多,砼质量及其保护层是内在因素;环境与载荷作用则是外在因素,不同的原因会造成不同的后果。首先讨论了混凝土耐久性的概念。接着分析了混凝土冻融作用破坏机理分析、混凝土缺陷检测、提高混凝土耐久性的措施,最后做了总结。     

关于城市河道整治中的生态护坡技术分析

本文分析了建设生态型河道的要求和特征,阐述了生态型河道建设的必然性,介绍了三维植被网护坡和植被型生态混凝土护坡技术在南京市河道整治中的应用,分析了这两种生态护坡技术的质量控制要点及在实际应用中应注意的问题。     

超声法检测混凝土内部缺陷的实例分析

超声法检测混凝土内部缺陷,具有探测距离大、不破坏结构性能、探伤灵敏度较高、周期短、成本低、操作简单、效率高等优点,该方法在建筑工程领域被广泛的应用。同时由于超声法对工作表面要求平滑、要求检验人员富有经验、对缺陷没有直观性等缺点,因此在使用超声法检测混凝土内部缺陷的过程中,应综合考虑各种因素,根据结构的具体形式,灵活运用检测方法,提高检出率,避免出现漏判和误判。超声波探伤混凝土内部缺陷影响因素较多,本文通过工程实例分析了混凝土内钢筋配制对检测结果的影响。     

生态混凝土应用研究进展

当今社会经济的不断发展,各种建筑材料对环境带来了不同程度的污染。随着人们环境保护意识逐渐提升,近年来,生态混凝土得到了广泛运用,在工程防护、植被绿化、美化环境、节约资源等方面发挥着重要作用。本文主要介绍生态混凝土的概念、优缺点、国内外的研究现状、制备工艺及其检测、力学性能、孔隙率、水质净化以及在各行业中的运用情况。通过各研究总结了解生态混凝土,以及整理出相关实验的制作过程,为日后生态混凝土的制作研究提供方法与思路。     

浅谈日欧生态水泥混凝土材料与技术——访日技术交流

摘要：生态混凝土是减轻地球环境负荷、与生态体系协调发展、创造舒适生活环境的混凝土材料。二战结束后,日本和德国等国对废弃混凝土进行了开发研究和再生利用,提出混凝土必须生态化、绿色化,同时开始利用废弃混凝土做骨料生产再生混凝土,并对其强度、耐久性、经济性等进行了研究。近年来我国也已经意识到生态水泥混凝土材料和技术是今后水泥混凝土行业发展的大趋势,这样才能使水泥混凝土行业走向可持续发展的道路。     

蒸压加气混凝土的孔结构及表征方法研究进展

蒸压加气混凝土因其质轻、保温性好、环保等优点而受到人们的重视。作为一种典型的宏观多孔建筑材料,蒸压加气混凝土的孔结构特征与其微观结构和性能有密切的关系。钙硅比、水料比、铝粉及工艺参数是影响蒸压加气混凝土孔结构的重要因素,孔隙率、孔径分布等孔结构特征与蒸压加气混凝土的强度、吸水性、干燥收缩、导热性能及耐久性等性能有紧密的联系。本文重点阐述了蒸压加气混凝土的孔结构特征及影响孔结构的主要因素,孔结构对蒸压加气混凝土性能的影响,并简述了蒸压加气混凝土孔结构现阶段主要采用的表征方法。     

Eco-concrete for sustainability: utilizing aluminium dross and iron slag as partial replacement materials

Emphasis on utilizing the industrial waste/discarded materials can be brought about by discovering innovative methods of disposal. One such a way of waste disposal can be through utilizing them in concrete production as a filler material or pozzolana. In this regard, the present study proposes to use the aluminium dross and granular iron slag as partial replacement materials for cement and natural sand, respectively, to develop eco-concrete. Nine mixes were produced with different proportions of cement, aluminium dross, sand and granular iron slag content. The aluminium dross was replaced at 5, 10, 15 and 20% of the weight of the cement. Initially, the optimal substitution percentage of aluminium dross was found without the substitution of iron slag based on the strength results. Later, by adopting the optimal aluminium dross percentage with cement, the granular iron slag was partially substituted at 10, 20, 30 and 40% of natural sand to find the overall optimal blend. The strength and durability properties of the M40 grade concrete employing these two admixture combinations were analysed. It was noticed that the strength and durability properties of the eco-concrete produced by incorporating aluminium dross ?5% and iron slag ?20% were comparable to that of conventional concrete. Furthermore, from the toxicity analysis, it was seen that the leaching of heavy and trace elements from the eco-concrete was negligibly small and within the limits. In near future, the cost-effective, eco-friendly materials and technologies can be opted as a perpetual strategy to overcome severe material shortages for resource conservation and economy.     

国内植生混凝土研究现状与展望

文章对植生混凝土的概念进行了准确界定,并对植生混凝土的物理、力学性能的影响因素进行了阐述,还对国内外植生混凝土的研究历史和现状进行了总结。对所能查询到的植生混凝土的研究成果文献进行了分析、归纳和总结,指出了植生混凝土研究的不足,并展望了未来植生混凝土的研究前景。     

Gradation characteristic analysis of vegetation‐type porous concrete

Porosity acts as a key role in realizing the planting function of vegetation‐type porous concrete. However, the porosity depends on the aggregate gradation characteristic. Then, compared with the gradation characteristic of normal concrete, the gradation characteristic of vegetation‐type porous concrete is discussed. Furthermore, the porosity calculation of vegetation‐type porous concrete with three kinds of grain‐size‐ranges (9.5 mm‐16 mm, 16 mm‐19 mm and 19 mm‐26.5 mm) is deduced. Results present that the stacking theory is more suitable than the filling theory to describe the aggregate accumulation pattern. Besides, the calculation formula is deduced, which can effectively calculate the porosity of vegetation‐type porous concrete.     

Spectral matching factors between Super S25 and New S25 photo cathodes and reflective radiation of objects

According to the response of photoelectric device to a light source, the formula of spectral matching factor of photo cathode-object combination is deduced. The spectral matching factors of Super S25 and New S25 photo cathodes for green vegetation and rough concrete are calculated and compared. For Super S251, the spectral-matching factors for green vegetation and rough concrete are 0.707 and 0.743, respectively, under the full-moon radiation and are 0.504 and 0.577, respectively, under the clear-star radiation. For Super S252, the full-moon factors are 0.561 (green vegetation) and 0.732 (rough concrete), and those for clear-star radiation are 0.338 (green vegetation) and 0.471 (rough concrete). For New S25, the full-moon factors are 0.741 (green vegetation) and 0.762 (rough concrete), and those for clear-star radiation are 0.603 (green vegetation) and 0.657 (rough concrete). An analysis of results shows that the spectral-matching factor has influence on the performance of a low-light level night vision system and is essential for evaluating the visual range of a night-vision system.     

Research on structural compatibility of eco-porous concrete and vegetation

To investigate the structural compatibility of eco-porous concrete (EPC) and vegetation, a simulation method (sand penetration coefficient) of structure compatibility between the eco-porous concrete (EPC) and vegetation was put forward. Furthermore, the relation between sand penetration coefficient and pore characteristics were analyzed, and the technology of acquiring equivalent pore size was optimized. The results present that the new simulation method, characterized by sand penetration coefficient, can effectively assess the ability of eco-porous concrete (EPC) to allow the root system to pass through. In addition, the real pore structure shape by “rubbing technology” can be easily and quickly obtained.     

Life cycle cost savings analysis on traditional drainage systems from low impact development strategies

Areas that are covered with natural vegetation have been converted into asphalt, concrete, or roofed structures and have increased surface impermeability and decreased natural drainage capability. Conventional drainage systems were built to mimic natural drainage patterns to prevent the occurrence of waterlogging in developed sites. These drainage systems consist of two major components: 1) a stormwater conduit system, and 2) a runoff storage system. Runoff storage systems contain retention basins and drywells that are used to store and percolate runoff, whereas conduit systems are combination of catch basins and conduit pipes used to collect and transport runoff. The construction of these drainage systems is costly and may cause significant environmental disturbance. In this study, low impact development (LID) methods that consist of extensive green roofs (GRs) and permeable interlocking concrete pavements (PICPs) are applied in real-world construction projects. Construction project documents were reviewed, and related cost information was gathered through the accepted bidding proposals and interviews of specialty contractors in the metropolitan area of Phoenix, Arizona. Results indicate that the application of both LID methods to existing projects can save an average of 27.2% in life cycle costs (LCC) for a 50-year service life and 18.7% in LCC for a 25-year service life on the proposed drainage system, respectively.     

用SIR-C航天飞机双频极化干涉雷达估计植被高度的方法研究

基于重复轨道航天飞机SIR—C的L和C波段极化干涉雷达数据,提出了一种将三阶段反演方法(Three—Stage Inversion)和ESPRIT(Estimation of Signal Parameters via Rotational Invariance Techniques)算法相结合的新的相位基植被高度估计方法。首先,基于L波段极化干涉数据,用三阶段反演方法获取植被覆盖地表下地形有效散射中心的相位;接着,基于c波段极化干涉数据,用ESPRIT算法估计植被冠层有效散射中心的相位;最后,对二者的相位差进行相位到高度的转换得到植被的高度。根据研究区域的实测林相数据,对该算法估计的植被高度结果进行了比较和验证,结果表明：该方法具有足够高的植被高度估计精度,如果能得到P和X波段的双频极化干涉雷达数据,该方法估计植被高度的精度将会得到进一步的提高。     

智能混凝土与结构

智能混凝土是通过将极少量具有某种特殊功能的材料复合于传统的混凝土材料中形成的具有多功能特性或某一种特殊功能特性的新型土木工程结构材料。与其他智能材料相比,智能混凝土是多功能本征性智能材料,可从本质上提高工程结构的性能。自感知混凝土(纳米混凝土、碳纤维混凝土)、自阻尼混凝土和自愈合混凝土等是智能混凝土研究的热点。总结了近年来作者在智能混凝土的制备、性能、机理,以及智能混凝土结构等方面的研究成果,并指出需进一步研究的问题。