Carbonation of low heat portland cement paste procured in water for different time

The carbonation technique was applied to accelerate the hydration of low heat portland cement (LHC). Before carbonation, the demoulded pastes were precured in water for 0, 2, 7, and 21 d, respectively. The results show that procuring time in water strongly influences the carbonation process. The phenolphthalein test indicates that the paste precured in water for a shorter time is more quickly carbonated than that for a longer time. The content of calcium hydroxide increases with increasing the procuring time in water, whereas, the amount of absorbed carbon dioxide changes contrarily. Scanning electron microscope (SEM) observation shows that portlandite always fills up big air bubbles in the paste during precuring in water, and the mercury intrusion porosimetry (MIP) results show that there are less large capillary pores in the paste precured in water for a longer time. It is found that the paste without precuring in water has more carbon dioxide absorption during curing in carbon dioxide atmosphere, and its total pore volume decreases remarkably with an increase in the carbonation time than that precured in water. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses indicate that the carbonate products are vaterite and calcite; CxSHy,, formed from carbonation has low BET surface area in comparison with that of C-S-H formed from curing in water.     

粉煤灰复合水泥浆体干燥收缩与孔结构关系的研究

采用氮吸附法研究了不同掺量粉煤灰对水泥浆体孔结构的影响,分析了干燥收缩与孔径分布、孔隙率、比表面积的关系。结果表明:粉煤灰的掺入使复合水泥浆体孔隙率、比表面积增加,细化样品孔结构的同时使较小毛细孔的比例减小,从而一定程度抑制了干燥收缩。     

不同结构特性ZrO2的制备及表征

采用沉淀法,通过控制合成条件制备出了具有不同晶相结构和孔结构特性的ZrO2。采用N2吸附、XRD、NH3-TPD及CO2-TPD等不同测试技术对ZrO2的晶相结构和孔结构特性进行了系统的表征研究。结果表明:较高温度和长时间老化沉淀物所制备的ZrO2,经焙烧后倾向于形成四方相;而常温及短时间老化沉淀物所制备的ZrO2,经焙烧后则倾向于形成单斜相。随着ZrO2焙烧温度的升高,其孔径增大,而比表面积、孔容和表面酸碱性减小。     

养护制度对粉煤灰复合水泥浆体干燥收缩及孔径分布的影响

将水泥试件在水中养护6天和13天后放入干燥养护箱中,测定其质量损失和干燥收缩。采用氮吸附方法测定不同龄期时的孔径分布。结果表明:粉煤灰复合水泥浆体,干燥收缩早期变化较为明显,随着龄期延长,变化逐渐变缓;水养时间延长,干燥收缩减小;不同水养时间养护后,粉煤灰复合水泥浆体4-40nm孔径体积含量减小,相应干燥收缩减小。     

污泥停留时间对SMBR净化受污染水源水的影响

为考察用于饮用水处理的浸没式膜生物反应器（SMBR）中适宜的污泥停留时间（SRT）,在平行运行的条件下对比研究了80d和20d两种SRT下SMBR净化受污染水源水的效能.结果表明,在80d的SRT下,SMBR对DOC、UV254、TOC、CODMn的去除率分别为19.6%、13.4%、27.7%和30.7%;而当SRT...     

三峡库区低水位运行期库尾支流筑坝对其水体CO2分压及排放的影响

为探究三峡库区低水位运行期间库尾支流河坝对其上下游水体CO₂分压、水气界面扩散通量的影响,于2019年8月对三峡库区库尾典型筑坝支流御临河进行采样研究。原位测定关键理化环境因子,采用顶空平衡法,结合亨利定律和薄边界层理论计算水体CO₂分压（p_CO2）及水气界面扩散通量（Flux（CO₂））。结果表明,库区低水位运行期御临河水体表层p_CO2为54.55~336.73 Pa,均值为206.68 Pa,Flux（CO₂）为1.65~67.84 mmol/（m²·d）,均值为39.01 mmol/（m²·d）,表现为大气CO₂排放源排放水平显著高于三峡库区中下游支流。御临河受其下游筑坝影响,河坝上游较近河段表现为湖泊型水体（流速v<0.05 m/s）,上游较远河段和下游表现为过渡型水体（v=0.05~0.2 m/s）。湖泊型水体p_CO2和Flux（CO₂）显著低于过渡型水体,且p_CO2随水深增加迅速增大。相关性分析及多元逐步回归分析表明,库区低水位运行期御临河p_CO2及Flux（CO₂）受水温、pH、DO、Chl-a等理化环境指标影响显著,Chl-a是影响p_CO2的最主要因素,p_CO2是影响Flux（CO₂）的最主要因素。     

Development of a drill energy utilization index for aiding selection of drill machines in surface mines

Drill machines used in surface mines, particularly in coal, is characterized by a very poor utilization(around 40%) and low availability(around 60%). The main purpose of this study is to develop a drill selection methodology and simultaneously a performance evaluation technique based on drill cuttings produced and drilling rate achieved. In all 28 blast drilled through were investigated. The drilling was accomplished by 5 different drill machines of Ingersoll-Rand and Revathi working in coal mines of Sonepur Bazari(SECL) and Block-II(BCCL). The drills are Rotary and Rotary Percussive type using tricone rock roller bits. Drill cuttings were collected and sieve analysis was done in the laboratory. Using Rosin Ramler Diagram, coarseness index(CI), mean chip size(d), specific-surface area(SSA) and characteristic particle size distribution curves for all the holes drilled were plotted. The predictor equation for drill penetration rate established through multiple regressions was found to have a very good correlation with an index of determination of 0.85. A comparative analysis of particle size distribution curves was used to evaluate the drill efficiency. The suggested approach utilises the area under the curve, after the point of trend reversal and brittleness ratio of the respective bench to arrive at drill energy utilization index(DEUI), for mapping of drill machine to bench. The developed DEUI can aid in selecting or mapping a right machine to right bench for achieving higher penetration rate and utilizations.     

高温水冷后循环加卸载条件下花岗岩的渗透性

针对水下隧道火灾喷水灭火降温过程中围岩的渗透性问题,对高温水冷后循环加卸载条件下花岗岩的渗透性开展了试验研究.以高温(25、400和900 ℃)水冷后的花岗岩试样为研究对象,通过轴向压应力循环加卸载过程中气体渗透性试验,研究花岗岩渗透率变化规律.结果表明:轴向压应力循环加卸载试验过程中,花岗岩试样的卸载模量随着高温水冷处理温度升高而减小,随着轴向压应力增大,卸载模量总体呈上升趋势,气体渗透率随温度升高而增大;花岗岩BET比表面积与BJH孔体积在900 ℃高温水冷后明显减小.     

沿海缺水灌区地表水地下水联合调配管理信息系统

根据沿海地区实际情况,集成以往的研究成果及相关数据,建立沿海缺水灌区地表水地下水联合调配管理信息系统.该系统具有友好的界面,是地理信息系统、数据库技术以及水资源·系统模拟优化等多技术综合集成的动态管理系统.模型具有一定的通用性,可为沿海缺水灌区地表水地下水规划管理服务,也可为各级水管部门准确及时提供水资源信息.     

皖南地区二叠系页岩储层微观孔隙特征及影响因素

皖南地区二叠系发育一定规模的富有机质泥页岩。为了深入研究该套泥页岩储层的微观孔隙特征,选取两口钻井岩芯样品进行了氮气吸附、压汞、氩离子抛光扫描电镜试验,结合泥页岩地球化学、有机岩石学和矿物组成特征探讨了微观孔隙发育的影响因素。结果表明:龙潭组和孤峰组泥页岩总体厚度大,总有机碳高,成熟度适中,矿物成分以石英、伊利石、长石和黄铁矿为主;龙潭组泥页岩有机质以固体沥青和镜质组为主,类型为Ⅱ Ⅲ型,其形态表现为片层状、条带状或块状,优势孔隙类型为晶间孔和微裂缝,有机孔发育较差,页岩比表面积和孔隙度分别介于6.80～41.62 m^2.g^-1和0.68%～4.44%,主要来自中孔;孤峰组泥页岩有机质以腐泥组和固体沥青为主,类型为Ⅱ型,其形态主要为薄膜状或填隙状,优势孔隙类型为有机孔,也发育一定的晶间孔和微裂缝,页岩比表面积介于3.12～49.45 m^2.g-¹,主要来自微孔,孔隙度介于0.86%～21.08%,主要来自中孔和大孔;总有机碳是这两套泥页岩比表面积的主要影响因素,但是对孔隙度起着明显的抑制作用;伊利石含量与比表面积之间存在一定的负相关性,与孔隙度之间无明显相关性。     

谱聚类在给水管网分区优化中的应用

利用图划分技术和图论算法实现给水管网分区。根据给水管网分析,确定分区数量,建立权重邻接矩阵并计算图拉普拉斯矩阵及其特征向量,通过多路图划分对隐藏在特征向量中的聚类信息进行数据挖掘,采用遗传算法和K均值方法实现最佳节点聚类。利用PageRank和最短路径算法确定水表和阀门位置,最终实现给水管网优化分区。实际给水管网模型分区实例表明所提方法在给水管网分区的有效性。     

GaAs中碳受主局域振动模光吸收特性

在ＧａＡｓ中碳受主局域振动模光吸收主带的低能侧发现一个吸收边带。研究了该边带的起因及其对主吸收带积分面积测定和主吸收带积分面积温主关系的影响。     

苛碱浓度对种分产品粒度变化规律的影响

氢氧化铝产品粒度存在周期性爆发性细化是我国氧化铝生产中拜耳法部分固有的现象,它严重干扰了拜耳法系统的正常运行.为探明产品粒度周期性细化的机理,在实验室模拟工业条件,结合激光粒度分析仪与扫描电子显微镜,研究了苛碱浓度对种分过程产品粒度周期性细化的影响规律.结果表明：铝酸钠溶液苛碱浓度增加,产品粒度波动的振幅变大,细化时间延长;苛碱浓度降低,产品粒度发生爆发性二次成核时间较早,但细化后粒度恢复为粗颗粒的速度较快.溶液浓度的变化对溶液分解率也有较大影响,降低溶液浓度能提高铝酸钠溶液的分解率.