Simplified Mixture Design for Production of Self-Consolidating Concrete

In this work, a methodology to achieve ordinary-, medium-, and high-strength self-consolidating concrete (SCC) with and without mineral additions is proposed. The inclusion of Class F fly ash increases the density of SCC but retards the hydration rate, resulting in substantial strength gain only after 28 days. This delayed strength gain due to the use of fly ash has been considered in the mixture design model. The accuracy of the proposed mixture design model is validated with the present test data and mixture and strength data obtained from diverse sources reported in the literature.

Micromechanical analysis of self compacting concrete

The micro-level properties of different self compacting concrete (SCC) mixes with and without mineral admixures are studied. The study considers SCC as a two phase material consisting of matrix and aggregate. Micro indentation technique is employed to obtain the hardness of individual phases and to compute the micro-property (modulus of elasticity). Using a self consistent homogenization procedure, the micro-property is scaled-up to obtain the macro-property which is shown to agree with the experimentally obtained macro values. It is seen that there exists a smaller interfacial transition zone at different ages of curing across all the mixes due to the presence of more fines in SCC. Also, there is no significant change in the property of the SCC having no fly ash or silica fume beyond 28 days whereas a substantial change in the micro and macro properties are seen in the SCC having fly ash and silica fume.

Envolvimento cardíaco e pulmonar na esquistossomose aguda e crônica de camundongos alimentados com dieta hiperlipídica

O objetivo desse trabalho foi avaliar as alterações no tecido cardíaco e pulmonar de camundongos dislipidêmicos, esquistossomóticos e seus controles que haviam sido eutanasiados com 9 (fase aguda) e 17 (fase crônica) semanas de infecção. Foram estudados quatro grupos de camundongos, segundo a dieta e tempo de infecção: dieta padrão (SCa e SCc), dieta hiperlipídica (HFCa e HFCc), dieta padrão infectados (ISCa e ISCc) e dieta hiperlipídica infectados (IHFCa e IHFCc). O coração e o pulmão foram retirados, seccionados e os fragmentos foram submetidos a processamento histológico e corados com Hematoxilina e Eosina e Picrosirius red. Foram realizadas análises histopatológicas dos dois órgãos, além de estudos estereológico (dissector óptico) e morfométrico (vasos, cardiomiócitos e quantificação de colágeno) do coração. Os grupos foram comparados pelos Testes T de Student e/ou ANOVA. Todos os animais com dieta hiperlipídica, infectados ou não, apresentaram menor densidade de número e número total de cardiomiócitos (p<0,05), além de vasos intramiocárdicos com lúmen mais reduzido e paredes mais espessas que os controles, independente da semana em que foram eutanasiados. Os cardiomiócitos dos grupos IHFCa e IHFCc estavam mais hiperplásicos (p<0,0001) e continham mais colágeno ao redor (p<0,05) que os dos demais grupos estudados. Os corações dos grupos IHFC, nas duas fases, apresentaram maior quantidade de nichos inflamatórios, inúmeras regiões contendo coagulação de fibras cardíacas, maior número de áreas com desaparecimento de fibras e proliferação de fibroblastos quando comparados aos grupos ISC. Os pulmões de camundongos do grupo IHFCc apresentaram aumento do número de reações granulomatosas e infiltrados perivasculares quando comparados aos demais grupos infectados. Esses dados sugerem que a infecção por S. mansoni causa danos às estruturas miocárdica e pulmonar que se intensificam com a interação com a dieta rica em lipídios.

Durability of similar self-compacting concrete batches produced in two different EU laboratories

The present study intends to evaluate the sensitivity of self-compacting concrete (SCC) mixtures, cast in two different laboratories of the European Union, with a focus on rheological parameters, mechanical characteristics and durability properties. Six SCC mixtures with different water-to-binder ratios and silica fume levels of cement replacement and two normally vibrated concrete (NVC) mixtures have been compared. It has been found that the reproducibility of similar mixtures is possible, when using different constituent materials that conform to the European Standards. Comparable rheological, mechanical and durability properties can be achieved. Open porosity and sorptivity appear to be more sensitive than chloride penetrability. © 2012 Elsevier Ltd. All rights reserved.

Reproducibility of self-compacting concrete batches between two different EU laboratories

Self Compacting Concrete (SCC) offers a wide variety of advantages during casting. Considering the worldwide uniformity of guidelines concerning the composition and casting instructions for the production of fresh SCC, there is a need to explore the reproducibility of similar self-compacting concrete batches between different countries. In the present study, the fresh properties of similar SCC batches produced in two different laboratories of the European Union are being compared and evaluated.

Durability performance of self-compacting concrete

Although self compacting concrete (SCC) is currently used in many countries, there is a fundamental lack of the intrinsic durability of the material itself. This article presents the outcomes from a research program on principal indicators that define the durability of SCC (sorptivity, porosity and chloride ion permeability) and compares these indicators with the corresponding parameters of conventional concrete. The results show, for the first time, that there is a correlation between the various durability indicators for the specific filler additives used in the mix designs incorporated in this paper. Such a correlation may be used to assess the durability of SCC without the need to rely on time consuming artificial weathering experimental procedures. © 2012 Elsevier Ltd. All rights reserved.

Determination of the rheological parameters of self-compacting concrete matrix using slump flow test

The classification of a concrete mixture as self-compacting (SCC) is performed by a series of empirical characterization tests that have been designed to assess not only the flowability of the mixture but also its segregation resistance and filling ability. The objective of the present work is to correlate the rheological parameters of SCC matrix, yield stress and plastic viscosity, to slump flow measurements. The focus of the slump flow test investigation was centered on the fully yielded flow regime and an empirical model relating the yield stress to material and flow parameters is proposed. Our experimental data revealed that the time for a spread of 500 mm which is used in engineering practice as reference for measurement parameters, is an arbitrary choice. Our findings indicate that the non-dimensional final spread is linearly related to the non-dimensional yield-stress. Finally, there are strong indications that the non-dimensional viscosity of the mixture is associated with the non-dimensional final spread as well as the stopping time of the slump flow; this experimental data set suggests an exponential decay of the final spread and stopping time with viscosity. © Appl. Rheol.

基于编译器的瞬时故障容错技术研究与实现

随着计算机芯片的速度不断提升，器件的门限电压越来越低，因此单粒子翻转的瞬时故障越来越容易发生。特别是在太空环境中的计算机系统，在宇宙射线的影响下，瞬时故障更为频繁，系统可靠性面临更突出的考验。 为了提高计算机系统的可靠性，一般有硬件冗余容错和软件冗余容错两种方法。相对硬件容错而言，软件容错的优点是价格便宜，性价比高，配置灵活等，缺点是会带来额外的时间和空间开销，而且给程序员带来编写额外的容错代码的工作量。近来出现了一些基于编译的软件容错方法，可在编译的过程中自动加入冗余容错逻辑，但是这类编译容错方法仍然会带来显著的时间空间开销。如何在保持容错能力的同时尽量降低时空开销，是有待继续研究的问题。 本文在编译容错方向上进行了进一步研究和实现，提出利用源代码中的变量信息对冗余容错逻辑进行了剪裁，在保证容错能力的同时降低了时空开销，对内存和寄存器中的数据进行保护。具体内容有： 1. 提出了一个容错编译环境SCC的设计蓝图，构建了一个容错编译工具的远 景目标。 2. 提出了一种指令级的编译容错检测方法VarBIFT ，提供检测瞬时故障的能力。平均只利用0.0069倍的时间损耗和0.3620倍的空间损耗就将发生瞬时故障时，程序正确执行和检测到故障的概率总和平均从39.1%提升到76.9%， 3. 提出了一种指令级的编译容错恢复方法VarRIFT ，提供从瞬时故障中恢复正确数据的能力。平均只增加0.043倍的时间损耗和0.69倍的空间损耗就将发生瞬时故障时，程序仍然正确执行的概率平均从44.8%提升到了78.7%。 4. 基于开源编译器LCC，实现了上述两个编译容错方法VarBIFT 和VarRIFT 。在容错方法的实现中只修改了跟具体CPU指令相独立的中间逻辑，所以这两个实现能够方便得移植到SPARC、MIPS等其他CPU架构上。 5. 开发了一个故障注入工具，并用它测试了上述两个编译容错方法VarBIFT和VarRIFT 的容错能力。

铀酰化合物的结构

本文用HMPA、TBPO与LIO_2(NO_3)_2 6H_2O和HPMBP反应，制备了LIO_2(NO_3)_2 2HMPA、LIO_2(PMBP)_2HMPA和LIO_2(PMBP)_2TBPO。分析了LIO_2(NO_3)_22HMPA的电子光谱，中红外、远红外及拉曼光谱，~1HNMR谱，并测定了晶体结构，说明了HMPA在配合物中的配位状况。对于LIO_2(PMBP)_2 HMPA和LIO_2(PMBP)_2TBPO，从测定的红外光谱及~1HNMR谱中可判断二者具有类似的结构。对前者晶体进行了X射线分析，获得了配合物的空间结构。将中性配体HMPA、TBPO、TPPO、DSMO和DMF加入到LIO_2(OX)_2的THF溶液中，制备了LIO_2(OX)_2 L的系列配合物。分析了它们的电子光谱和红外光谱。选择了系列化合物中的LIO_2(OX)_2 TBPO测定了晶体结构，证实了从光谱中所得的结构信息。以上所表征的配合物的结构与堆积模型的预测一致。从而实验证明了堆积模型的正确性。用HMPA、TPPO与LIO_2Ac_2 2H_2O和HOX作用，制备了LIO_2Ac_2·HMPA·THF、LIO_2Ac_2 TPPO·THF和LIO_2(OX)_2 TPPO；前两个为同系物，LIO_2Ac_2 TPPO THF的单晶结构分析表明其为双聚形式存在。从堆积模型出发，分析了产生双聚结构的原因以及游离的THF在晶体形成过程中的作用，对LIO_2(OX)_2 TPPO·THF和LIO_2(OX)_2·TPPO进行堆积模型分析，预测了它们的双聚及三聚结构特征。这些与LIO_2(OX)_2 TPPO的初步结构分析结果是一致的。本工作还进行了铀酰配合物电子结构的SCC-DV-X_α方法计算。结合LIO_2Ac_3Na的光电子能谱，分析了LIO_2Ac_3~-的结构特征。给出了堆积模型的理论基础，解释了堆积饱和及堆积均匀规律。并分析了该模型在铀酰配合物中正确性的原因。

硫酸盐还原菌和极化电位对海洋结构用钢在海泥中应力腐蚀开裂敏感性的影响

海洋设施长期处于恶劣的腐蚀环境中，如不加以防护，一旦发生应力腐蚀开裂（SCC），损失就会极为惨重。海底泥土区环境十分重要，因为管线和平台桩腿等都埋在海底泥中。海底泥中硫酸盐还原菌（SRB）十分活跃，而且为了防止腐蚀，海泥中的设施无一例外地采取了阴极保护，相当于设施处在长期稳定的充氢状态。因此非常有必要研究海泥中的活性SRB和极化电位对海洋结构用钢在海泥中的氢渗透行为和SCC敏感性造成的影响，弄清SCC发生和发展的过程以便采取相应的措施减缓或防止SCC。 本文通过慢应变速率拉伸实验（SSRT）、电化学阻抗谱（EIS）技术、动电位扫描极化曲线测定实验和氢渗透实验等研究了海泥中SRB和极化电位对16Mn钢和管线钢X56（API X56）的SCC敏感性造成的影响。 从渤海海泥中富集得到SRB菌种，并做出了SRB在海泥中的生长曲线；在荧光显微镜下观察SRB为弧状，可以归为脱硫弧菌属，为革兰氏阴性菌；海泥中活性SRB数量与硫电位等主要腐蚀环境因子具有一定的对应关系。 SSRT结果表明，施加阴极极化电位可以使试样断裂脆性特征明显，SCC敏感性增大；海泥中活性SRB浓度越高，断裂脆性特征越明显，SCC敏感性越大。在含SRB海泥中或阴极极化电位条件下，两种钢都容易发生SCC，氢脆（HIC）起主要作用。 随着浸泡天数的增加，试样在灭菌海泥中的Rp一直增大；在含SRB海泥中Rp先增大，又变小，并呈现出显著的Warburg阻抗特征；在灭菌海泥中，两种试样在阳极电位范围内无SCC敏感区，而在阴极电位范围内有明显的SCC敏感区；在含SRB海泥中，在阳极电位范围和阴极电位范围内均有SCC敏感区；SRB代谢产物既有阳极去极化作用，又有阴极去极化作用，能使腐蚀电流密度增加。 活性SRB的存在能够促进试样在海泥中的氢渗透；在实海工程应用中，两种钢在含SRB海泥中的氢渗透电流密度大约是在不含SRB海泥中的3~4倍。阴极极化电位能够促进试样在灭菌海泥中的氢渗透。在含SRB海泥中对试样施加阴极极化电位，氢渗透电流密度大于不加阴极极化电位时的氢渗透电流密度，也大于在不含SRB的海泥中的氢渗透电流密度。

Corrosion failure of marine steel in sea-mud containing sulfate reducing bacteria

The corrosion failure behavior of marine steel is affected by stress, which exists in offshore structures at sea-mud region. The sulfate reducing bacteria (SRB) in the sea-mud made the steel more sensitive to stress corrosion cracking (SCC) and weaken the corrosion fatigue endurance. In this paper, a kind of natural sea-mud containing SRB was collected. Both SCC tests by slow strain rate technique and corrosion fatigue tests were performed on a kind of selected steel in sea-mud with and without SRB at corrosion and cathodic potentials. After this, the electrochemical response of static and cyclic stress of the specimen with and without cracks in sea-mud was analyzed in order to explain the failure mechanism. Hydrogen permeation tests were also performed in the sea-mud at corrosion and cathodic potentials. It is concluded that the effect of SRB on environment sensitive fracture maybe explained as the consequences of the acceleration of SRB on corrosion rate and hydrogen entry into the metal.

The synergy between deformation and anodic dissolution of an austenitic stainless steel in acidic chloride solution

In corrosion medium, metals can deform under tensile stress and form a new active surface with the anodic dissolution of the metals being accelerated. At the same time, the anodic dissolution may accelerate the deformation of the metals. The synergy can lead to crack nucleation and development and shorten the service life of the component. Austenitic stainless steel in acidic chloride solution was in active dissolution condition when stress corrosion cracking (SCC) occurred. It is reasonable to assume that the anodic dissolution play an important role, so it's necessary to study the synergy between anodic dissolution and deformation of austenitic stainless steels. The synergy between deformation and anodic dissolution of AISI 321 austenitic stainless steel in an acidic chloride solution was studied in this paper. The corrosion rate of the steel increased remarkably due to the deformation-accelerated anodic and cathodic processes. The creep rate was increased while the yield strength was reduced by anodic dissolution. The analysis by thermal activation theory of deformation showed a linear relationship between the logarithm of creep rate and the logarithm of anodic cur-rent. Besides, the reciprocal of yield strength was also linearly dependent on the logarithm of anodic current. The theoretical deductions were in good agreement with experimental results.

Stress corrosion cracking of AISI 321 stainless steel in acidic chloride solution

The stress corrosion cracking (SCC) of LambdaISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) technique and fracture mechanics method. The fractured surface was characterized by cleavage fracture. In order to clarify the SCC mechanism, the effects of inhibitor KI on SCC behaviour were also included in this paper. A study showed that the inhibition effects of KI on SCC were mainly attributed to the anodic reaction of the corrosion process. The results of strain distribution in front of the crack tip of the fatigue pre-cracked plate specimens in air, in the blank solution (acidic chloride solution without inhibitor KI) and in the solution added with KI measured by speckle interferometry (SPI) support the unified mechanism of SCC and corrosion fatigue cracking (CFC).

城市发展与地质环境相互作用机制及数量分析—北海市可持续发展战略研究

Based on a viewpoint of an intricate system demanding high, this thesis advances a new concept that urban sustainable development stratagem is a high harmony and amalgamation among urban economy, geo-environment and tech-capital, and the optimum field of which lies in their mutual matching part, which quantitatively demarcates the optimum value field of urban sustainable development and establishes the academic foundation to describe and analyze sustainable development stratagem. And establishes a series of cause-effect model, a analysissitus model, flux model as well as its recognizing mode for urban system are established by the approach of System Dynamics, which can distinguish urban states by its polarity of entropy flows. At the same time, the matter flow, energy flow and information flow which exist in the course of urban development are analyzed based on the input/output (I/O) relationships of urban economy. And a new type of I/O relationships, namely new resources-environment account, are established, in which both resource and environment factors are considered. All above that settles a theoretic foundation for resource economy and environment economy as well as quantitative relationships of inter-function between urban development and geoenvironment, and gives a new approach to analyze natinal economy and urban sustainable development. Based on an analysis of the connection between resource-environmental construct of geoenvironment and urban economy development, the Geoenvironmental Carrying Capability (GeCC) is analyzed. Further more, a series of definitions and formula about the Gross Carrying Capability (GCC), Structure Carrying Capability (SCC) and Impulse Carrying Capability (ICC) is achieved, which can be applied to evaluate both the quality and capacity of geoenvironment and thereunder to determine the scale and velocity for urban development. A demonstrative study of the above is applied to Beihai city (Guangxi province, PRC), and the numerical value laws between the urban development and its geoenvironment is studied by the I/O relationship in the urban economy as following: · the relationships between the urban economic development and land use as well as consumption of underground water, metal mineral, mineral energy source, metalloid mineral and other geologic resources. · the relationships between urban economy and waste output such as industrial "3 waste", dust, rubbish and living polluted water as well as the restricting impact of both resource-environmental factors and tech-capital on the urban grow. · Optimization and control analysis on the reciprocity between urban economy and its geoenvironment are discussed, and sensitive factors and its order of the urban geoenvironmental resources, wastes and economic sections are fixed, which can be applied to determine the urban industrial structure, scale, grow rate matching with its geoenvironment and tech-capital. · a sustainable development stratagem for the city is suggested.

Estimation of soil organic partition coefficients: from retention factors measured by soil column chromatography with water as eluent

The retention factors (k) of 104 hydrophobic organic chemicals (HOCs) were measured in soil column chromatography (SCC) over columns filled with three naturally occurring reference soils and eluted with Milli-Q water. A novel method for the estimation of soil organic partition coefficient (K-oc) was developed based on correlations with k in soil/water systems. Strong log K-oc versus log k correlations (r>0.96) were found. The estimated K-oc values were in accordance with the literature values with a maximum deviation of less than 0.4 log units. All estimated K-oc values from three soils were consistent with each other. The SCC approach is promising for fast screening of a large number of chemicals in their environmental applications. (C) 2002 Elsevier Science B.V. All rights reserved.