基于损伤演化方程的混凝土寿命预测方法

基于混凝土的冻融或腐蚀损伤演化方程,提出了一套预测混凝土结构使用寿命的基本方法与理论体系;用单一冻融因素作用下的大量试验数据验证了混凝土的损伤演化方程;通过专门设计的盐湖卤水腐蚀单一因素和(干湿循环+盐湖卤水腐蚀)双重因素、3.5％质量浓度的NaCl盐冻试验,研究了青海盐湖钾肥和北京城市立交桥主体结构混凝土的使用寿命预测问题.结果表明:青海盐湖钾肥工程不宜采用普通混凝土和高强混凝土;C60引气高性能混凝土在盐冻作用下满足北京城市立交桥50年的使用要求.     

建筑能源审计中暖通系统能耗拆分方法的讨论

暖通空调能耗在建筑能耗中所占比重较大,同时,暖通空调系统庞大、用能设备多、使用较为分散。通过对两个建筑和能耗数据的分析,采用两种不同的暖通空调拆分方法,计算出建筑分项能耗指标。通过两种方法的应用,认为能源审计的拆分应根据建筑能耗的特点变换不同的拆分方法,最终将不影响能耗拆分质量。     

Long-term balanced fertilization decreases arbuscular mycorrhizal fungal diversity in an arable soil in North China revealed by 454 pyrosequencing

A balanced fertilization can increase crop yields partly due to stimulated microbial activities and growths. In this study, we investigated arbuscular mycorrhizal fungi (AMF) in arable soils to determine the optimal practices for an effective fertilization. We used pyrosequencing-based approach to study AMF diversity, as well as their responses to different long-term (>20 years) fertilizations, including OM (organic manure) and mix chemical fertilizers of NP (nitrogen-phosphorus), NK (nitrogen-potassium), and NPK (nitrogen-phosphorus-potassium). Results revealed that 124,998 of 18S rRNA gene fragments were dominated by Glomeromycota with 59,611 sequences, generating 70 operational taxonomic units (OTUs), of which the three largest families were Glomeraceae, Gigasporaceae and Acaulosporaceae. In Control and NK plots, AMF diversity and richness significantly decreased under long-term P fertilizations, such as NP, NPK, and OM. Concomitantly, the AMF community structure shifted. Supported by canonical correspondence analysis, we hereby propose that long-term balanced fertilization, especially P fertilizer with additional N fertilizer, helps the build-up of soil nutrients. Consequently, some AMF community constituents are sacrificed, propelled by the self-regulation of plant-AMF-microbes system, resulting in an agro-ecosystem with a better sustainability. This knowledge would be valuable toward better understandings of AMF community in agro-ecosystem, and long-term ecosystem benefits of the balanced fertilization.     

Humic acid facilitates the transport of ARS-labeled hydroxyapatite nanoparticles in iron oxyhydroxide-coated sand

Hydroxyapatite nanoparticles (nHAP) have been widely used to remediate soil and wastewater contaminated with metals and radionuclides. However, our understanding of nHAP transport and fate is limited in natural environments that exhibit significant variability in solid and solution chemistry. The transport and retention kinetics of Alizarin red S (ARS)-labeled nHAP were investigated in water-saturated packed columns that encompassed a range of humic acid concentrations (HA, 0-10 mg L(-1)), fractional surface coverage of iron oxyhydroxide coatings on sand grains (λ, 0-0.75), and pH (6.0-10.5). HA was found to have a marked effect on the electrokinetic properties of ARS-nHAP, and on the transport and retention of ARS-nHAP in granular media. The transport of ARS-nHAP was found to increase with increasing HA concentration because of enhanced colloidal stability and the reduced aggregate size. When HA = 10 mg L(-1), greater ARS-nHAP attachment occurred with increasing λ because of increased electrostatic attraction between negatively charged nanoparticles and positively charged iron oxyhydroxides, although alkaline conditions (pH 8.0 and 10.5) reversed the surface charge of the iron oxyhydroxides and therefore decreased deposition. The retention profiles of ARS-nHAP exhibited a hyperexponential shape for all test conditions, suggesting some unfavorable attachment conditions. Retarded breakthrough curves occurred in sands with iron oxyhydroxide coatings because of time-dependent occupation of favorable deposition sites. Consideration of the above effects is necessary to improve remediation efficiency of nHAP for metals and actinides in soils and subsurface environments.     

海上摄像平台运动对目标在靶面成像位置影响的分析

布置在海面上的摄像平台的运动难免会对目标在摄像系统中的成像位置产生影响。分析这些运动对目标成像位置的影响,为是否需要采用稳定装置和采用什么样的稳定装置提供了理论依据,因此具有较大的应用价值。     

连续多年施用硫酸钾肥对烟田土壤及烟株硫素含量的影响

为明确连续施用硫酸钾肥对烟田土壤及烟株硫含量及硫分配的影响,设置并开展了3年的硫酸钾肥定位试验。研究结果表明,根际土的有效硫含量受烤烟生育期及施肥量的影响较小,但根外土有效硫随施肥量的增加而增加,且以旺长期最高。土壤全硫含量受烟草根系及施肥量的影响,根际土中含量显著低于根外土,且两者均随施肥量的增加而显著增加（对照的根际土除外）。硫酸钾肥显著增加了叶部全硫含量及其积累量,并且随施用量的增加而增加;其对茎部的影响次之,对根部影响最小,但施肥量对成熟期各部位全硫分配率的影响较小。连续3年施用含硫量达125．4kg／hm0的肥料后,各叶位的含硫量均达到0．7％及以上。因此,应根据烟田土壤及烟叶硫含量的实际情况,合理规范硫酸钾类肥料在烟草生产中的施用量。     

一起110kV电缆终端爆炸事故分析

针对发生的一起110 kV电缆终端爆炸事故,通过事故情况调查,对故障电缆终端的解剖、分析,认为电缆终端生产密封工艺存在缺陷是终端爆炸事故的主要原因,并针对这种情况提出了相应的对策,避免再次发生此类事件。     

硅粉密相气力输送技术在多晶硅生产中的应用

介绍某多晶硅厂对硅粉加料采用密相气力输送技术的输送方式和工艺流程,分析了该气力输送系统中主要设备和管道、阀门选型及设计时的考虑因素。     

改良剂对重金属复合污染土壤的钝化修复研究

研究了泥炭、凹凸棒土及不同施用方式对土壤重金属有效态的影响。结果表明:各处理对土壤溶液的pH值影响不大;泥炭的钝化效果明显比凹凸棒土好,但在和凹凸棒土配合施用后,其钝化效果有所下降,而表施处理对DTPA提取态重金属的钝化效果并不明显。     

Preparation of mesoporous NiO with a bimodal pore size distribution and application in electrochemical capacitors

Mesoporous nickel oxide with a porous structure exhibiting a bimodal pore size distribution (2.6 and 30.3 nm diameter pores) has been synthesized in this paper. Firstly, a mesoporous precursor of coordination complex Ni₃(btc)₂·12H₂O (btc = 1,3,5-benzenrtricarboxylic acid) is synthesized based on the metal-organic coordination mechanism by a hydrothermal method. Then mesoporous NiO with a bimodal size distribution is obtained by calcining the precursor in the air, and characterized by transmission electron microscopy and N₂ adsorption measurements. Such unique multiple porous structure indicates a promising application of the obtained NiO as electrode materials for supercapacitors. The electrochemical behavior has been investigated by cyclic voltammogram, electrochemical impedance spectra and chronopotentiometry in 3 wt.% KOH aqueous electrolyte. The results reveal that the prepared NiO has high-capacitance retention at high scan rate and exhibits excellent cycle-life stability due to its special mesoporous character with bimodal size distribution.