浅谈岩土工程勘察质量在工程建设中的重要性

通过某大型工程建设实例阐述了岩土工程勘察资料的准确性对工程建设的影响,及其在工程建设中的重要性.     

导向钻进非开挖铺管技术的应用

介绍了导向钻进非开挖铺管技术的工作原理和工程实例，同时提出了在施工中应注意的问题。     

低压电气设备防误操作装置的设计与实现

文中就我们所研制的ＤＦＳ型低压电气设备防误操作装置的功能特点、设计思路、工作原理及需要改进的问题进行了说明与探讨。     

电气运行实践教学改革的研究与实施

根据当前工作现场对人才的要求,提出以能力培养为核心的素质教育作为运行实习应努力改进的方向,通过对以往教学的分析和研究,结合当前运行实习中的具体情况,确定运行实习教学改革的思路、目标和方法.经过几年具体实施,确实取得了一定的成效,毕业学生在运行岗位上受到用人单位的肯定.     

铬渣堆场污染土壤中重金属铬的存在形态

采用Tessier连续提取ICP-AES法对湖南某厂铬渣堆场土壤中重金属铬的存在形态(水溶性铬、交换态铬、碳酸盐结合态铬、有机结合态铬、铁锰结合态铬和残渣态铬)进行分析.研究结果表明,铬渣堆场土壤铬污染严重;铬渣堆场下土壤中大部分铬以铁锰结合态形式存在,在铬渣堆场周围和离铬渣堆场5 km处未污染土壤中铬大部分以残渣态的形式存在;交换态铬和碳酸盐结合态铬在土壤各剖面层次的含量相差不是很大,而可溶性铬和残渣态铬在0~40 cm土层富集,有机结合态铬和铁锰结合态铬在40~60 cm土层富集.     

关于拟动态安全域的理论分析

本文引入拟动态安全域来刻画电力系统稳定性。若电力系统当前运行状态位于拟动态安全域内,则该系统经历事故后仍然是稳定的。太文通过分析事故中系统轨道的性质,讨论了拟动态安全域的拓扑性质,为拟动态安全域的应用提供了理论基础。     

Optimization of Cr（VI） bioremediation in contaminated soil using indigenous bacteria

Bench-scale soil column experiments were carried out to evaluate the effectiveness of Cr(VI) bioremediation process in soils by using indigenous bacteria with the addition of bacteria nutrient media. Effects of particle size, spray intensity, initial Cr(VI) concentration, circulation mode and soil depth on Cr(VI) remediation were studied. Results show that soils after 6 d remediation with spray intensity controlled in the range of 29.6-59.2 mL/min could well fulfill the requirement of concrete aggregate and roadbed material usage, for the leaching toxicity concentration of the Cr(VI) in treated soils under the chosen condition is far less than 5 mg/L. The leaching toxicity and fractions of both hexavalent chromium and trivalent chromium from remediated soils were determined and compared with that of untreated soil. The results show that water soluble Cr(VI) declines from 1520.54 mg/kg to 0.68 mg/kg, exchangeable Cr(VI) decreases from 34.83 mg/kg to 0.01 mg/kg and carbonates-bonded Cr(VI) falls from 13.55 mg/kg to 0.68 mg/kg. Meanwhile, a corresponding increase in carbonate-bonded Cr(III), Fe and Mn oxides-bonded Cr(III) and organic matter-bonded Cr(III) are found. It reveals that indigenous bacteria can leach out water soluble Cr(VI), exchangeable Cr(VI) and carbonates-bonded Cr(VI) from contaminated soil followed by converting into carbonate-bonded Cr(III), Fe and Mn oxides-bonded Cr(III), organic matter-bonded Cr(III) and residual Cr(III).     

CFRP-PCPs复合筋混凝土柱偏压柱受力性能的试验研究

通过15根碳纤维预应力棱柱体复合筋(Carbon Fiber Reinforced Plastics Prestressed Concrete Prisms,简称"CFRPPCPs复合筋")混凝土柱进行偏心受压试验,考虑相对偏心距、复合筋配筋率、CFRP筋张拉控制应力和普通钢筋配筋率4个变化参数对复合筋混凝土柱受力性能的影响。观察了试件的受力过程及破坏形态,获取了试件开裂荷载、极限承载力、荷载-侧向变形曲线等重要数据,分析了4个变化参数对CFRP-PCPs复合筋混凝土柱偏心受压作用下的开裂荷载和极限承载力的影响规律。研究结果表明:CFRP-PCPs复合筋混凝土偏压柱与普通钢筋混凝土偏压柱的受力过程及破坏形态相似,试件的开裂荷载和极限承载力均随相对偏心距的增大而降低;提高CFRP筋张拉控制应力、增大复合筋配筋率和普通钢筋配筋率均能有效提高CFRP-PCPs复合筋混凝土柱的开裂荷载和极限承载力。     

Removal of Cr（Ⅲ） and Cr（Ⅵ） from aqueous solution by adsorption on sugarcane pulp residue

Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(III) and Cr(VI)) from wastewater. In this work, the kinetics, isotherms of Cr(III) and Cr(VI) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(VI) and Cr(III) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr(VI) removal differs from that of the Cr(III) removal. The Cr(VI) removal percentage decreases with increasing pH values, while the Cr(III) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(VI) and Cr(III) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr(VI) and 3.446 mg/g for Cr(III). Moreover, SPR reveals higher adsorption capacity for Cr(III) than that for Cr(VI), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(VI)-containing wastewater treatment. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

Thermodynamic study on reaction path of Hg（ II ） with S（ II ） in solution

The mercury sulfidation experiments were conducted in the pH range from 1 to 13. The results show that Hg(Ⅱ) reacted with equimolar S(Ⅱ) has the lowest remained Hg(Ⅱ) concentration (9.7 μg/L) at pH 1.0 and the highest remained concentration (940.8 ug/L) at pH 13.0. Meanwhile, the changes of pH values were monitored exactly, which reveal that solution pH values change when mixing the same pH value solutions of HgCl_2 and Na_2S. In order to explain the phenomena and determine the reaction paths of Hg(Ⅱ) reacting with S(Ⅱ) in the solution, the concerned thermodynamics was studied. Species of S(Ⅱ)-H_2O system and Hg(Ⅱ)-H_2O system at different pH values were calculated, and then the species distribution diagrams of S(Ⅱ)-H_2O system, Hg(Ⅱ)-H_2O system and Hg(Ⅱ)-Cl~-0H~~-H_2O system were drawn. Combining the experimental data and thermodynamic calculation, the mechanism of Hg(Ⅱ) reacting with S(Ⅱ) was deduced. The results indicate that different species of S(Ⅱ) and Hg(Ⅱ) have the diverse reaction paths to form HgS precipitate at different pH values and the standard Gibbs free energies change(△_rG_m~Θ) of those equations are also calculated, which can provide a guidance for mercury-containing wastewater treatment with Na_2S.