建材研究的新热点——黄河淤泥沙综合利用进展及前景展望

简要介绍了黄河淤泥沙的特性及相关情况,论述了黄河於泥综合利用研究的进展及主要成果,概述了其工业化开发的现状,分析了其存在的问题,对其发展前景进行了预测。黄河淤泥沙综合利用工作是关系到国计民生、千秋万代的大事,具有重要的现实意义和深远的历史意义。     

建材研究的新热点——黄河沙综合利用进展及前景展望

简要介绍了黄河淤泥沙的特性及相关情况,论述了黄河泥综合利用研究的进展及主要成果,概述了其工业化开发的现状,分析了其存在的问题,对其发展前景进行了预测,黄河淤泥沙综合利用工作是关系到国计民生、千秋万代的大事,具有重要的现实意义和深远的历史意义。     

工艺参数对淤泥沙合成O′-Sialon-SiC-Fe3Si粉的影响

以天然的可再生资源淤泥沙为主要原料,以固体废弃物金属矿尾矿为调剂料,利用炭黑作还原剂,采用碳热还原氮化法合成了O′-Sialon-SiC-Fe3Si粉。用X射线衍射法测定了产物相组成及相对含量,研究了合成温度和恒温时间对反应过程的影响。结果表明,合成温度对O′-Sialon-SiC-Fe3Si粉体的合成过程影响显著,随着合成温度的升高,产物中O′-Sialon相含量增大,1500℃时O′-Sialon相含量最大,是最佳的合成温度。恒温时间对产物相组成的影响不十分显著,但较长的恒温时间可以使还原氮化反应进行得更充分,恒温6h的试样中O′-Sialon相含量达到了83%,是较理想的恒温时间。合成过程中SiO的挥发导致试样较大的质量损失,且随着合成温度的升高和恒温时间的延长而增大。     

工艺参数对淤泥沙合成O＇-Sialon-SiC-Fe3Si粉的影响

以天然的可再生资源淤泥沙为主要原料,以固体废弃物金属矿尾矿为调剂料,利用炭黑作还原剂,采用碳热还原氮化法合成了O＇-Sialon-SiC-Fe3 Si粉.用X射线衍射法测定了产物相组成及相对含量,研究了合成温度和恒温时间对反应过程的影响.结果表明,合成温度对O＇-Sialon-SiC-Fe3Si粉体的合成过程影响显著,随着合成温度的升高,产物中O＇-Sialon相含量增大,1500℃时O’-Sialon相含量最大,是最佳的合成温度.恒温时间对产物相组成的影响不十分显著,但较长的恒温时间可以使还原氮化反应进行得更充分,恒温6h的试样中O＇-Sialon相含量达到了83％,是较理想的恒温时间.合成过程中SiO的挥发导致试样较大的质量损失,且随着合成温度的升高和恒温时间的延长而增大.     

水利工程软土地基处理方法

软土地基是指压缩层主要由淤泥、淤泥质土或其他高压缩性土构成的地基。承载能力很低,一般不超过50KN每平方米。本文介绍了多种软土地基的处理方法,并对其质量控制进行分析。     

羟乙基纤维素接枝聚己内酯的生物降解性能

通过三甲基硅(TMS)基团改性保护技术,成功制备了羟乙基纤维素(HEC)接枝聚己内酯(HEC-g-PCL)聚合物,利用红外光谱及核磁共振波谱对合成产物进行了结构验证。利用微生物降解法与活性淤泥法分别对HEC-g-PCL进行了生物降解实验。结果表明,经过霉菌不同时间降解,扫描电子显微镜(SEM)观测产物的表观形貌发生了明显变化;活性淤泥降解HEC-g-PCL产物表明,HEC-g-PCL在中性淤泥状具有自然活性的土壤中,经四周时间,降解率达到8.0%。     

压力灌浆在加固公路路基中的应用及问题

公路路基主要由填土、淤泥或淤泥质土、粉、细砂组成。文章介绍了加固高速公路路基的工艺原理、工艺流程及结果。本文结合高速公路某段高填土路基沉降工程治理,说明灌浆法的施工程序和方法,并对以后的公路路基中的应用提出了新的期望。     

淤泥地质管道顶管施工技术研究

本文针对淤泥地质地下水位高、土质差、易塌方的特点,着重介绍了淤泥地段的管道顶管穿越时顶管方式的筛选.对全断面土压平衡掘进式顶管和全断面土压平衡挤压式顶管的施工技术进行了阐述,总结了各自施工技术的要点.     

爆炸法处理软基在深淤泥港口工程中的应用

介绍爆炸法在外海深淤泥港口工程中的应用及质量检测结果，显示了爆炸法处理深淤泥软基的优势，具有良好的经济技术价值。     

利用钢渣和淤泥烧制陶粒的研究

介绍了以钢渣和淤泥为原料烧制陶粒的工艺,研究了钢渣掺量、烧成温度以及焙烧时间对陶粒性能的影响.结果表明,在淤泥中掺入一定量的钢渣可以烧制出符合标准规定的陶粒,所得陶粒吸水率很低,但钢渣掺量不宜过高.     

高聚物基骨替代材料复合技术的研究进展

概述了高聚物基骨替代材料复合技术的研究现状，着重介绍了高聚物基体和增强材料的选择要求，注射模塑成型、仿生沉积、原位复合等复合技术，并评价了不同基体材料的生物学性能。     

On the “Colloidal Retentivity“ of Gelatin against Silver Halide

The term colloidal retentivity is introduced as a measure of the ripening characteristics of photographic gelatins and for describing the progress of the ripening of photographic emulsions. A diluted emulsion is allowed to sediment in a cell for a few minutes. The cell is then alternately illuminated from above and below the cell. The intensity of the light scattered in a horizontal plane when the cell is illuminated from above is defined as the colloidal retentivity. It is influenced by the more rapidly setting grains which attenuate the beam from below.     

Sediment flux and the Anthropocene

Data and computer simulations are reviewed to help better define the timing and magnitude of human influence on sediment flux--the Anthropocene epoch. Impacts on the Earth surface processes are not spatially or temporally homogeneous. Human influences on this sediment flux have a secondary effect on floodplain and delta-plain functions and sediment dispersal into the coastal ocean. Human impact on sediment production began 3000 years ago but accelerated more widely 1000 years ago. By the sixteenth century, societies were already engineering their environment. Early twentieth century mechanization has led to global signals of increased sediment flux in most large rivers. By the 1950s, this sediment disturbance signal reversed for many rivers owing to the proliferation of dams, and sediment load reduction below pristine conditions is the dominant signal today. A delta subsidence signal began in the 1930s and is now a dominant signal in terms of sea level for many coastal environments, overwhelming even the global warming imprint on sea level. Humans have engineered how most water and sediment are discharged into the coastal ocean. Hyperpycnal flow events have become more common for some rivers, and less common for other rivers. Bottom trawling is now widespread, suggesting that even continental shelves have received a significant but as yet quantified Anthropocene impact. The Anthropocene attains the level of a geological climate event, such as that seen in the transition between the Pleistocene and the Holocene.     

黄河泥沙颗粒分析回归数学模型的探讨

黄河泥沙颗粒级配是研究水利工程及河床演变中泥沙问题的基本资料 ,黄河泥沙颗粒级配分析是一项重要的基础性研究工作。本文结合引进国际先进的激光粒度分析仪 ,开发应用于黄河泥沙颗粒分析工作的实际 ,研究解决了激光法测量泥沙级配资料换算到传统法测量泥沙级配资料的问题 ,探讨运用数学回归的方法 ,建立了回归数学公式 ,并对其合理性进行了检验分析 ,为保证黄河历史泥沙颗粒分析资料的连续性、完整性、一致性开展了探索性工作。     

Adaptive conversion of a high-order mode beam into a near-diffraction-limited beam

We present a new method for efficiently transforming a high-order mode beam into a nearly Gaussian beam with much higher beam quality. The method is based on modulation of phases of different lobes by stochastic parallel gradient descent algorithm and coherent addition after phase flattening. We demonstrate the method by transforming an LP11 mode into a nearly Gaussian beam. The experimental results reveal that the power in the diffraction-limited bucket in the far field is increased by more than a factor of 1.5.     

On the role of surface energy and surface stress in phase-transforming nanoparticles

The role of surface energy and surface stress has been a topic of extensive discussion since the seminal work by Gibbs [Gibbs JW. The scientific papers of J. Willard Gibbs. Vol. I: Thermodynamics. New York and Bombay:Longmans, Green, and Co; 1906; Gibbs JW. Collected works. New Haven:Yale University Press; 1957]. Both quantities have the same value for liquids, but not for solids. The distinction between these terms is of special importance for phase transforming nanoparticles (precipitates, transforming or melting/solidifying single particles), since surface quantities scale as the inverse of the particle size relative to volume quantities.

Continuum mechanics and, especially, the concept of configurational forces (stresses) provide a convenient framework for distinguishing between “surface energy”, “surface tension” and “surface stress”. Therefore, this progress report gives a rather detailed introduction into the continuum mechanics and thermodynamics of a moving surface.

The transformation conditions for the cases where an entire nanoparticle transforms suddenly and when the transformation is interface-driven are discussed. A global transformation condition for a sudden phase-transforming nanoparticle is explained. For the interface-driven transformation, the concept of configurational forces is applied to derive a local transformation condition in a material point at the phase interface.

Four examples of nanoparticles (growing precipitate, growing solid nucleus in liquid, melting particle, solidifying particle) are studied in detail. The surface energy and surface stress are shown to contribute to the thermodynamic driving force on the interface in different ways. These contributions are quantified and discussed with respect to the case of a sudden transformation of the nanoparticle.     

Effect of vortex formation on sediment transport at dual pipe intakes

Vortex formation and subsequent sediment transport into the intake due to sea water withdrawal is one of the problems in coastal engineering. The effect of vortex formation on rate of sediment transport at coastal dual pipe intakes was investigated using a scaled physical model. Experiments were performed on dual pipe intakes at three common intake withdrawal directions (vertical, horizontal and with angle of 45°). In each experiment, the class of vortex with respect to its strength was determined. Particle tracking velocimetry (PTV) was employed to measure tangential velocity of vortices. Results indicated that the rate of sediment transport was considerably affected by the strength of formed vortices. The rate of transported sediment was increased by increasing the strength of formed vortex. Moreover, amount of sediment transport was affected by angle of pipe intakes. It could be concluded that the minimum and maximum rates of sediment transport occur for inclined and horizontal intakes, respectively.     

Determination of naphthenic acids in crude oils using nonaqueous ion exchange solid-phase extraction

A method is presented for the routine, rapid, and quantitative analysis of aliphatic and naphthenic acids in crude oils, based on their isolation using nonaqueous ion exchange solid-phase extraction cartridges. The isolated acid fractions are methylated and analyzed by gas chromatography and gas chromatography/mass spectrometry. The method is effective on both light and heavy oils and is capable of providing mechanistic information of geochemical significance on the origin of the acids in the oils. Analysis of oils that were solvent extracted from laboratory and field mesocosm marine sediment oil degradation studies indicate that this new method of analyzing the products of hydrocarbon biodegradation may be a useful tool for monitoring the progress of bioremediation of oil spills in the environment.     

Allocating reforestation areas for sediment flow minimization: an?integer programming formulation and?a?heuristic solution method

Policy and decision makers dealing with environmental conservation and land use planning often require identifying potential sites for contributing to minimize sediment flow reaching riverbeds. This is the case of reforestation initiatives, which can have sediment flow minimization among their objectives. This paper proposes an Integer Programming (IP) formulation and a Heuristic solution method for selecting a predefined number of locations to be reforested in order to minimize sediment load at a given outlet in a watershed. Although the core structure of both methods can be applied for different sorts of flow, the formulations are targeted to minimization of sediment delivery. The proposed approaches make use of a Single Flow Direction (SFD) raster map covering the watershed in order to construct a tree structure so that the outlet cell corresponds to the root node in the tree. The results obtained with both approaches are in agreement with expert assessments of erosion levels, slopes and distances to the riverbeds, which in turn allows concluding that this approach is suitable for minimizing sediment flow. Since the results obtained with the IP formulation are the same as the ones obtained with the Heuristic approach, an optimality proof is included in the present work. Taking into consideration that the heuristic requires much less computation time, this solution method is more suitable to be applied in large sized problems.     

Vertical distribution of polychlorinated biphenyl congeners in sediment core from Thane Creek area of Mumbai, India

In recent years there has been a growing concern all over the globe about the marine pollution due to persistent organic pollutants. Sediments, which is an important component of marine environment can serve as sorbent or concentrator for various persistent organic pollutants including Polychlorinated Biphenyls (PCBs). Transport and fate of PCB congeners in sediment depends on their physicochemical characteristics. In this study, the depth profile of accumulated PCBs in Thane Creek sediments of Mumbai, India, was studied. The sediment core samples were collected using a gravity corer, processed and analysed for different PCB congeners. Analysis of PCBs in the sediment samples were carried out using gas chromatography system equipped with electron capture detector. The study on vertical distribution of PCBs in sediment could reflect the geochemical history including changes due to anthropogenic releases into the system. The surface segment shows the downward trend for these compounds, indicating slow phase out of PCBs after ban. The concentration and composition of different homologues varies at different depth. An attempt has also been made to find out the various sources of PCBs which could have contributed to these compounds by performing factor analysis over the observed concentrations of the PCB compounds in the core sediment.