Organic removal by denitritation and methanogenesis and nitrogen removal by nitritation from landfill leachate

A system consisting of a two-stage UASB and anoxic-oxic reactor was used to enhance COD and nitrogen removal from landfill leachate. To improve denitrification efficiency, the raw leachate with recycled final effluent was pumped into the first-stage UASB (UASB1) to carry out simultaneous denitrification and methanogenesis. The results over 180 d show that the maximum organic removal rate in UASB1 and UASB2 was 12.5 and 8.5 kgCODm(-3)d(-1) in the oxic zone of the A/O reactor, respectively. The COD and biochemical oxygen demand (BOD5) removal efficiency of the system was 80-92% and about 99%, respectively. Without controlling temperature (17-30 degrees C) and dissolved oxygen (0.5-4.0 mgL(-1)), the maximum NH4+-N removal rate was 0.68 kg NH4+-Nm(-3)d(-1), and about 99% of NH4+-N removal was obtained by nearly complete nitritation. The 81-93% total nitrogen removal was obtained by complete denitrification in the UASB1 and in the anoxic zone of the A/O reactor. Fluorescence in situ hybridization (FISH) analysis of the sludge samples from A/O reactor showed that ammonia oxidizing bacteria (AOB) consisted 4% of the eubacterium, while nitrite oxidizing bacteria (NOB) counted less than 0.2% of that. The study shows that the main factors achieving and maintaining nitritation are a proper range of free ammonia concentration obtained by dilution recycled final effluent that inhibits NOB but not AOB; effective control on aeration time by indication of "ammonia valley" on pH profile; and highly efficient denitrification and its reproducing alkalinity to result in pH above 8.5.     

增材制造技术在模具制造中的应用研究

介绍了增材制造技术的优点,阐述了增材制造技术在模具制造中的各种制造方法及特点,叙述了利用增材制造技术实现模具复合材料和梯度功能材料的应用,指出了增材制造技术的应用前景。     

柔性砷化镓太阳电池

介绍了柔性砷化镓太阳电池的基本结构;分析了柔性砷化镓太阳电池的制备工艺,即在Ga As衬底上生长一层牺牲层,再在牺牲层上生长Ⅲ-Ⅴ族太阳电池,最后使用选择性高的腐蚀液将牺牲层腐蚀掉,得到薄膜太阳电池以及可重复使用的衬底,以期达到提高太阳电池功率质量比和降低生产成本的目的;对电池有待于进一步研究的问题进行了展望。     

苯部分加氢制环己烯钌基催化剂研究进展

环己烯是重要的化工原料及中间体,广泛应用于合成纤维及其他工业领域。介绍了苯部分加氢制环己烯的技术路线,该技术路线具有安全环保和节能高效的特点,其中,催化反应体系是该技术的关键要素。重点概述了近年来对液相苯部分加氢催化体系中钌基催化剂的研究,包括催化剂前驱体、催化剂制备方法、载体、助催化剂以及添加剂对催化剂性能和产物选择性等的影响。介绍了已工业化的旭化成和神马集团的苯部分加氢工艺。环己烯的市场前景广阔,苯部分加氢工艺是一条经济效益高的工艺路线,实现催化体系的突破对于该工艺至关重要,但存在催化剂成本高、易失活和环己烯收率低的问题。     

Genetic types and geochemical characteristics of natural gases in the Jiyang Depression, China

Natural gases were widely distributed in the Jiyang Depression with complicated component composition, and it is difficult to identify their genesis. Based on investigation of gas composition, carbon isotope ratios,light hydrocarbon properties, as well as geological analysis, natural gases in the Jiyang Depression are classified into two types, one is organic gas and the other is abiogenic gas. Abiogenic gas is mainly magmatogenic or mantlederived CO2. Organic gases are further divided into coaltype gas, oil-type gas, and biogas according to their kerogen types and formation mechanisms. The oil-type gases are divided into mature oil-type gas(oil-associated gas)and highly mature oil-type gas. The highly mature oil-type gases can be subdivided into oil-cracking gas and kerogen thermal degradation gas. Identification factors for each kind of hydrocarbon gas were summarized. Based on genesis analysis results, the genetic types of gases buried in different depths were discussed. Results showed that shallow gases(\1,500 m) are mainly mature oil-type gases, biogas, or secondary gases. Secondary gases are rich in methane because of chromatographic separation during migration and secondary biodegradation. Secondary biodegradation leads to richness of heavy carbon isotope ratios in methane and propane. Genesis of middle depth gases(1,500–3,500 m) is dominated by mature oil-type gases.Deep gases(3,500–5,500 m) are mainly kerogen thermal degradation gas, oil-cracking gas, and coal-type gas.     

Light absorption distribution of prostate tissue irradiated by diffusing light source

Determination of light absorption distribution in the prostate tissue irradiated by diffusing light source is important for the treatment planning.In this paper,a three-dimensional(3D)optical model of human prostate is developed,and the light absorption distribution in the prostate tissue is estimated by Monte Carlo simulation method.Light distribution patterns including 3D distributions in the tissue model irradiated by two diffusing light sources are obtained and compared.Also,the impacts of length and energy of cylinder diffusing light source on the irradiance volume are demonstrated.Those results will be significant for the nondestructive qualitative assessments of photodosimetry in biomedical phototherapy.     

包络变形对阶比分析结果的影响及消除方法

转速变化的滚动轴承故障诊断通常先采用计算阶比跟踪技术消除变转速的影响,再进行阶比分析获得故障特征。然而,等角度重采样会引起冲击包络变形进而导致阶比分析结果产生偏差,在转速变化范围较大时这个偏差必须要受到重视。本文的主要工作是介绍了等角度重采样方法,仿真了包络变形对阶比分析结果的影响,给出了峰值点间隔变化量详细的理论推导,提出了通过修正角度变换值来消除包络变形影响的方法,并进行了实验验证。研究结果显示,包络在宽窄方向的变形对阶比分析结果没有影响;相邻包络峰值点间隔的变化对阶比分析结果产生影响;在角度序列逐点减去峰值点间隔变化量可消除包络变形对阶比分析结果的影响。     

超细晶轻合金的制备及超塑性研究进展

超细晶材料具有优异的超塑性能,综述了通过大塑性变形方法获得镁、铝合金超细晶材料的超塑性能研究进展和通过大塑性变形和热氢处理获得超细晶钛合金的超塑性能,展望了超细晶轻合金的发展趋势。     

建筑工程资料管理中存在的问题及优化措施

在一部分施工企业中,建筑工程资料的管理工作不完善,存在很多问题,使得工程不能尽快完成,最终出现成本超支的情况,因此建筑工程资料的管理是至关重要的内容.基于此,需要提高管理者的管理水平和职业素养,全方面地对管理者进行监管评价.     

潮汐应力对滑坡的触发机理及与时间相关性的研究

滑坡发生的时间具有明显的周期分布规律特征,日月引力潮是其中重要的影响因素。从固体潮汐理论出发,推导作用于坡体的潮汐应力表达式,阐述了潮汐应力对边坡稳定性的影响。通过考虑潮汐应力作用的改进安全系数法,剖析了潮汐应力触发滑坡的机理。以某典型土坡为例,论述潮汐应力的周期性变化,计算边坡安全系数与并分析其与时间的相关性,结果表明,潮汐应力与边坡安全系数均呈明显日周期及半日周期变动,且安全系数的波动反映该边坡接近临界状态。