基于能值分析的城市物质代谢研究

采用能值分析方法,构建了基于城市物质代谢通量指标、代谢存量指标和代谢效率指标的城市物质代谢指标体系,并以北京、天津、上海和重庆四个直辖市为例计算了2005年四城市物质代谢状况。分析结果表明:北京市代谢效率最低;上海市代谢通量和代谢存量最大,但是代谢效率不容乐观;重庆市代谢通量和代谢存量在四个城市中居于末位,但是代谢效率最高;天津市在四个城市中代谢呈中等水平。最后根据分析结果对城市今后的可持续发展提出了意见和建议。     

模糊语言视角下城市轨道交通施工风险评价

为了降低城市轨道交通工程在施工过程中的风险,从模糊语言视角对城市轨道交通施工风险进行分析.首先,通过文献分析和现场调查,建立风险评价指标体系;其次,利用区间直觉模糊区间熵计算专家权重和准则权重;然后,利用区间直觉模糊不确定语言集进行风险因素排序和风险评价;最后,以西安地铁1号线五路口车站施工为例,与FANPCE方法进行对比分析,验证所构建模型的可行性和有效性.研究表明,所构建模型有助于同时表达风险数据的模糊性和语言描述性,计算结果采用区间值的形式能够弱化风险数据的不确定性,使计算结果更符合工程实际,有助于更准确地预知主要风险因素和风险状态.     

基于博弈论组合赋权的航道水域通航安全评价

为有效降低航道水域通航过程中发生事故的风险,将组合赋权方法应用于航道水域通航安全评价中.通过调研和查阅资料确定了航道通航安全评价指标体系,基于该指标体系建立了基于博弈论组合赋权法的航道水域通航安全评价模型.利用博弈论将层次分析法、熵权法、可拓学3种方法计算所得权重进行最优组合,兼顾专家决策者的主观属性及数据蕴含的不确定性和动态可拓性,然后基于可拓学关联度的概念对航道关于各评价等级的关联关系进行综合评价,得到最终评价结果,并对计算结果从权重角度进行灵敏度分析,考察结果的稳定性和可靠性.最后,以宁波-舟山港为例,选取部分航道对该安全评价模型进行验证,结果表明该评估模型合理、有效.     

脉动通风在螺旋隧道施工期的应用研究

为提高施工期通风排除污染物效率,将脉动通风方法应用于螺旋隧道中,通过理论分析研究脉动通风在隧道施工期排除污染物的原理,采用FLUENT软件模拟不同脉动幅值、脉动频率下隧道内污染物浓度变化情况。研究结果表明:脉动通风可有效减少螺旋隧道内涡流区面积,优化隧道风流流场;脉动通风方式可使积聚在涡流区内的污染物产生纵向脉动速度,并加强风流横向脉动;脉动通风对爆破后排出CO气体效果不明显,但对降低喷浆过程粉尘浓度效果显著,数值模拟与理论研究结果吻合;排除污染物效果与脉动幅值无明显关系,与频率关系显著,且频率较小时效果更好。     

用于湿法净化黑烟表面活性剂筛选的数学模型研究

湿法净化燃煤窑炉中的黑烟,关键在于表面活性剂对炭黑的润湿、增溶和降低表面张力作用.根据研究筛选的数学模型,计算AEO-9和SDBS混合表面活性剂溶液的亲水亲油平衡值HLB、临界胶束浓度CMC与胶束形成吉布斯自由能ΔG0mf.通过实验测得不同配比AEO-9和SDBS溶液的CMC和处于该CMC时黑烟的去除效率η,分析混合溶液中HLB、CMC、ΔG0mf与η的关系,建立新的数学模型.结果表明,理论CMC与实测CMC吻合度较好;HLB与ln[CMC]线性相关;ΔG0mf与η存在二次函数关系.降低CMC可以有效增大HLB,增加溶解度,减小形成胶束的吉布斯自由能,降低表面张力,使形成胶束的反应更容易自发进行,有效提高黑烟去除效率.     

Removal of antimony from antimony mine flotation wastewater by electrocoagulation with aluminum electrodes

Antimony (Sb) has received increasing environmental concerns due to its potential toxic and carcinogenic properties. In the present work, the electrocoagulation technique was used to treat the flotation wastewater from a heavy antimony polluted area, and the mechanism of removing Sb was also investigated. The study focused on the effect of operation parameters such as current density, initial pH and standing time on the Sb removal efficiency. Antimony concentration of below 1 mg/L in the treated wastewater was achieved, which meets the emission standards established by State Department of Environmental Protection and State Administration of China for Quality Supervision and Inspection and Quarantine of China.     

Simultaneous removal of chromium and arsenate from contaminated groundwater by ferrous sulfate: Batch uptake behavior

Chromium and/or arsenate removal by Fe(II) as a function of pH, Fe(II) dosage and initial Cr(VI)/As(V) ratio were examined in batch tests. The presence of arsenate reduced the removal e ciency of chromium by Fe(II), while the presence of chromate significantly increased the removal e ciency of arsenate by Fe(II) at pH 6–8. In the absence of arsenate, chromium removal by Fe(II) increased to a maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH. The increment in Fe(II) dosage resulted in an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidic conditions. Chromium removal by Fe(II) was reduced to a larger extent under neutral and alkaline conditions than that under acidic conditions due to the presence of 10 mol/L arsenate. The presence of 20 mol/L arsenate slightly improved chromium removal by Fe(II) at pH 3.9–5.8, but had detrimental e ects at pH 6.7–9.8. Arsenate removal was improved significantly at pH 4–9 due to the presence of 10 mol/L chromate at Fe(II) dosages of 20–60 mol/L. Elevating the chromate concentration from 10 to 20 mol/L resulted in a further improvement in arsenate removal at pH 4.0–4.6 when Fe(II) was dosed at 30–60 mol/L.     

Pretreatment of heterocyclic pesticide wastewater using ultrasonic/ozone combined process

Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe diameter, initial pH and O3 dosage on the COD removal were studied. The results showed that the ultrasonic/O3 process significantly improved the biodegradability and reduced the biological toxicity of the wastewater. The ratio of BOD5/COD was increased from 0.03 to 0.55 and the EC50 increased from 11% to 52% under ultrasonic/O3 treatment. Low ultrasonic frequency brought better COD removal. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable. The influences of ultrasonic power and probe diameter were small. With an increase in O3 dosage, COD removal was e ectively improved. The optimal operational parameters for the combined process on COD removal were ultrasonic frequency 20 kHz, initial pH 9.00, ultrasonic power 300Wand dosage of O3 454.8 mg/(L min), under which the e ciency of COD removal reached 67.2%.     

模糊层次分析法在储罐施工HSE风险中的应用

储罐施工过程中存在各种潜在的风险,为了做好储罐施工过程中的HSE管理工作,进行风险评估是关键.本文以新疆某联合站储罐施工工程为例,从“人、物、环、管理”四个方面对储罐施工中可能出现的风险进行了识别,建立了基于模糊层次分析法的风险评估指标体系,计算出各递阶层次风险指标的权重值与层次u的权重值及总排序,并制定了具有针对性的...     

测定总氮的影响因素探讨

针对测定总氮过程中空白值偏高的问题,重点分析了实验环境、实验用水、试剂、玻璃器皿、消解过程等因素对空白值的影响,并提出减少空白值偏高的相应对策.