温度变化对水泥土强度特性和破坏性状的影响

为研究温度对水泥土强度和破坏性状的影响,选用粘土和粉土这两种素土制成水泥土试样,分别在25°C±2°C、10°C±2°C和0°C±2°C的温度下进行养护,随后测试各龄期试样的单轴抗压强度,并观测各试样的破坏特征。研究表明:随着龄期的增长,温度变化对峰值应变的影响在减小;龄期较短(1~5天)时,水泥土单轴抗压强度对温度变化不敏感,在龄期7~40天,提高养护温度,水泥土单轴抗压强度显著增大;随着温度的升高,水泥土强度显著提高,但增长的趋势越来越缓慢;低温情况下水泥粘土的强度都比水泥粉土低,而一旦提高温度,水泥粘土的强度便超过水泥粉土;较低温度下养护的水泥土表现出比较明显的脆性破坏,迅速产生裂缝。     

轻钢龙骨复合墙体抗剪承载力计算

轻钢龙骨复合墙体抗剪承载能力是轻钢龙骨体系建筑设计的关键参数。轻钢龙骨复合墙体由结构罩面板通过自攻螺钉与龙骨相连构成,其抗剪承载力与钢龙骨、结构板、自攻螺钉均有关系,影响因素较多,主要依赖试验确定,计算理论尚不成熟。本文借鉴木龙骨墙体抗剪承载力的确定方法,推导了轻钢龙骨复合墙体抗剪承载力的计算公式,并与试验结果进行了比较。结果表明,所推出的公式是合理可信的,可用于轻钢龙骨体系建筑中复合墙体的抗剪承载力计算。     

水泥基材固化含油污泥的析出性能

以水泥作为固化剂对中原油田文一污的含油污泥进行了固化处理,固化块的强度随着水泥量／污泥量的增大而增大,当水泥量／污泥量为2．0时,强度为16．07Mpa。通过正交试验。确定了浸泡时间及水泥量／污泥量是影响固化块浸出液中含油量的两个主要因素。在25℃、浸泡时间120h、水泥量／污泥量在1．0～1．8,浸出液含油量低于5mg／L。浸出液的有毒元素含量符合GB5085．3-1996的要求。     

激光表面处理对工业级锆基块体非晶合金弯曲变形和缺口韧性的影响

目的 改善块体非晶合金的弯曲力学性能,同时考虑航空结构材料选材的经济性,研究激光表面处理工艺对工业级Zr_49.7Ti₂Cu_37.8Al₁₀Er_0.5块体非晶合金弯曲变形和缺口韧性的影响规律。方法 采用低纯原料和低真空制备条件获得工业级Zr_49.7Ti₂Cu_37.8Al₁₀Er_0.5块体非晶合金试样,考虑到弯曲条件下试样受到拉伸和压缩2种正应力状态,研究不同处理工艺和激光处理表面对试样弯曲变形和缺口韧性的影响。结果 当激光处理表面位于弯曲试样的2个侧表面时,其对试样的塑性变形能力和断裂强度没有明显的影响,但会显著降低试样的缺口韧性,从(56.4±3.4)MPa·m^1/2降低到(26.2±4.8)MPa·m^1/2;激光处理表面位于弯曲试样的受拉侧时,试样的弯曲断裂强度从2 150 MPa降低到1 800 MPa;当激光处理表面位于...     

FX-4和FX-17典型橡胶密封圈加速老化性能研究

目的 研究FX-4和FX-17典型橡胶密封圈的加速老化性能。方法 对初始压缩率为14%和20%的FX-4和FX-17这2种橡胶密封圈,进行5个温度点不同时长的加速老化试验,通过试验测定FX-4和FX-17橡胶密封圈的拉伸强度、扯断伸长率、硬度以及压缩永久变形等4个性能指标,并进行分析和比较。结果 硬度指标随老化温度以及老化时间的变化不明显。拉伸强度与扯断伸长率在200℃老化试验后,均出现明显的下降趋势,但在同一老化温度下老化10、70d后,拉伸强度与扯断伸长率未发生明显的变化。在较低的老化温度时,压缩永久变形率随老化温度以及老化时间的变化不明显;在150、200℃温度老化后,压缩永久变形率随着老化时间的增加而呈上升趋势。结论 FX-4与FX-17橡胶密封圈的压缩永久变形率在老化温度点较低时,受温度的影响不显著,在同一温度下随老化时间的增加呈上升趋势;在老化温度点较高时,压缩永久变形率随着老化时间的增加而呈上升趋势。     

Levels and major sources of PM2.5 and PM10 in Bangkok Metropolitan Region

This research was the first long-term attempt to concurrently measure and identify major sources of both PM₁₀ and PM_2.5 in Bangkok Metropolitan Region (BMR). Ambient PM₁₀ and PM_2.5 were evaluated at four monitoring stations and analyzed for elemental compositions, water-soluble ions, and total carbon during February 2002–January 2003. Fifteen chemical elements, four water-soluble ions, and total carbon were analyzed to assist major source identification by a receptor model approach, known as chemical mass balance. PM₁₀ and PM_2.5 were significantly different (p < 0.05) at all sites and 24 h averages were high at traffic location while two separated residential sites were similar. Seasonal difference of PM₁₀ and PM_2.5 concentrations was distinct between dry and wet seasons. Major source of PM₁₀ at the traffic site indicated that automobile emissions and biomass burning-related sources contributed approximately 33% each. Automobiles contributed approximately 39 and 22% of PM₁₀ mass at two residential sites while biomass burning contributed about 36 and 28%. PM₁₀ from re-suspended soil and cooking sources accounted for 10 to 15% at a residential site. Major sources of PM_2.5 at traffic site were automobile and biomass burning, contributing approximately 32 and 26%, respectively. Biomass burning was the major source of PM_2.5 mass concentrations at residential sites. Meat cooking also accounted for 31% of PM_2.5 mass at a low impact site. Automobile, biomass burning, and road dust were less significant, contributed 10, 6, and 5%, respectively. Major sources identification at some location had difficulty to achieve performance criteria due to limited source profiles. Improved in characterize other sources profiles will help local authority to better air quality.     

长江南京段水体及市政自来水中多种OPEs的分布特征

采用HPLC-MS/MS法监测长江南京段横断面水、水源水、出厂水中12种有机磷酸酯类化合物(OPEs)残留,考察其分布特征及自来水厂对其处理效果。结果表明:12种OPEs在采集的横断面水和水源水水样中8种被检出,自来水出厂水水样中除TEHP外其余11种OPEs均为检出,OPEs暴露于水源水与地表水程度相似;除TCPP、TDCP、TCEP浓度出现降低外,其余OPEs浓度水平均未出现明显的处理效果;生态风险评估显示长江南京段横断面水、水源水、出厂水主要检出物质OPEs的风险熵值均低于1,表明不具有环境生态高风险。     

动态固相微萃取-气相色谱质谱法测定水中多种异味有机物

采用动态固相微萃取技术富集水样中2-异丙基-3-甲氧基吡嗪、2-异丁基-3-甲氧基吡嗪、2-MIB、β-环柠檬醛、2,4,6-三氯苯甲醚、GSM、α-紫罗酮和β-紫罗酮等8种异味有机物,并用气相色谱质谱法测定。通过优化试验条件,使方法在2. 00 ng/L～100 ng/L范围内线性良好,方法检出限为1. 0 ng/L～4. 4 ng/L。空白水样3个质量浓度水平的加标回收率为81. 0%～121%,6次测定结果的RSD为1. 7%～8. 9%。将该方法用于一水库实际水样的测定,结果 2-MIB、β-环柠檬醛、α-紫罗酮和β-紫罗酮检出,其余均为未检出。     

Receptor modeling for source apportionment of polycyclic aromatic hydrocarbons in urban atmosphere

This study reports source apportionment of polycyclic aromatic hydrocarbons (PAHs) in particulate depositions on vegetation foliages near highway in the urban environment of Lucknow city (India) using the principal components analysis/absolute principal components scores (PCA/APCS) receptor modeling approach. The multivariate method enables identification of major PAHs sources along with their quantitative contributions with respect to individual PAH. The PCA identified three major sources of PAHs viz. combustion, vehicular emissions, and diesel based activities. The PCA/APCS receptor modeling approach revealed that the combustion sources (natural gas, wood, coal/coke, biomass) contributed 19–97% of various PAHs, vehicular emissions 0–70%, diesel based sources 0–81% and other miscellaneous sources 0–20% of different PAHs. The contributions of major pyrolytic and petrogenic sources to the total PAHs were 56 and 42%, respectively. Further, the combustion related sources contribute major fraction of the carcinogenic PAHs in the study area. High correlation coefficient (R ² > 0.75 for most PAHs) between the measured and predicted concentrations of PAHs suggests for the applicability of the PCA/APCS receptor modeling approach for estimation of source contribution to the PAHs in particulates.     

C、D、M_f值综合异常交汇区在华北及其西部地区中强震前的中期异常变化

在华北及其西部地区用描述地震分布时、空、强基本特点的空间集中度C、地震危险度D、地震强度因子Mf 进行交汇寻找综合异常区预测未来中强震 ,预测震中位置在 1 5°半径之内。以实例显示综合异常区存在的稳定性和对未来较强地震的可预测性 ,并对比分析了大华北地区不同区域的应用效果 ,认为其差异是由资料详尽程度决定的。