三种化合物浸泡处理对石棉晶格结构和表面电荷的影响

为了研究经柠檬酸铝、混合稀土或亚硒酸钠浸泡处理温石棉对温石棉晶格结构和表面电荷的影响,用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后,通过透射电镜测定其衍射环直径的大小,分析石棉晶格结构的改变,并利用石棉纤维吸附亚甲蓝能力的测定方法,分析温石棉表面电荷。结果显示,用三种化合物处理石棉后,其衍射环直径均增大,而且用三种化合物处理后的石棉对亚甲蓝的吸附能力均明显降低,并且随着化合物剂量的增加其降低愈明显。上述结果表明,用三种化合物处理石棉,均可改变石棉的晶格结构,且可能减少其表面电荷。     

含硬夹矸高瓦斯低透气性煤层多向聚能爆破技术研究

针对在含硬夹矸高瓦斯低透气性煤层开采时，一方面煤层瓦斯抽采困难，另一方面煤层中的坚硬夹矸难破碎的问题，开展含硬夹矸高瓦斯低透气性煤层多向聚能爆破研究。理论上，分析多向聚能装药对爆破的影响，引入多向聚能影响系数，计算得出了不同方向上裂隙的范围。通过相似模拟试验，验证了多向聚能爆破实际效果；利用LS-DYNA数值模拟软件，对不同装药方式爆破作用下煤与夹矸裂隙的发育特征及应力演化规律进行了数值模拟研究。研究结果表明:多向聚能爆破能够将爆破能量积聚在夹矸弱化和煤层增透的方向上，形成以导向裂隙为主，大量分支裂隙为辅的裂隙网，在夹矸弱化和煤层增透方向上的应力峰值分别为普通爆破的1.21倍和1.16倍。多向聚能爆破能够在提高破碎坚硬夹矸能力的同时提升煤体中裂隙的发育程度，从而大幅优化爆破效果。     

天然石英砂的表面络合模型研究

天然泥沙颗粒表面特性复杂,其与营养物质及重金属之间的相互作用,是研究天然水体水环境效应的关键科学问题之一.本文以石英砂为例,在考虑天然泥沙表面形貌引起的电荷非均匀分布的基础上,建立了统计意义上的表面电荷分布-表面电位数学关系,并修正表面络合模型,对表面络合常数采用更合理的静电力校正,模拟营养物质及重金属在天然泥沙颗粒表面的吸附-解吸关系.同时,表面滴定实验及吸附实验数据被用来进行模型验证.结果表明,泥沙颗粒的吸附特性受pH值、水相平衡浓度和背景离子强度等影响,考虑颗粒表面电荷非均匀分布的修正模型,更接近天然泥沙的吸附特性,相比传统表面络合模型,能够更好地模拟吸附结果.     

Unraveling the size distributions of surface properties for purple soil and yellow soil

Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. > 10, 1–10, 0.5–1, 0.2–0.5 and < 0.2 μm) for a purple soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (< 1 μm), and almost half of the specific surface area and surface charge came from the smallest particles (< 0.2 μm). Vermiculite, illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the < 0.2 μm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties.     

横向双极电除尘器性能实验研究

为了提高现有电除尘器的除尘效果,提出一种横向双极电除尘器,将其与常规电除尘器在相同条件下进行伏安特性、压力损失、除尘效率性能对比。结果表明:横向双极电除尘器的压力损失比常规电除尘器约高30%;横向双极电除尘器的伏安特性优于普通电除尘器;在平均场强2.1~3.2 k V/cm,平均风速1.0~1.5 m/s的范围内,常温常压下,对中位径为25.405μm的烧结粉尘的除尘效率,横向双极电除尘器与常规电除尘器相比有显著提高,并且随着电场平均风速的提高,横向双极电除尘器的优势更加明显。     

Characterization of odorous charge and photochemical reactivity of VOC emissions from a full-scale food waste treatment plant in China

Food waste treatment plants (FWTPs) are usually associated with odorous nuisance and health risks, which are partially caused by volatile organic compound (VOC) emissions. This study investigated the VOC emissions from a selected full-scale FWTP in China. The feedstock used in this plant was mainly collected from local restaurants. For a year, the FWTP was closely monitored on specific days in each season. Four major indoor treatment units of the plant, including the storage room, sorting/crushing room, hydrothermal hydrolysis unit, and aerobic fermentation unit, were chosen as the monitoring locations. The highest mean concentration of total VOC emissions was observed in the aerobic fermentation unit at 21,748.2-31,283.3 μg/m³, followed by the hydrothermal hydrolysis unit at 10,798.1-23,144.4 μg/m³. The detected VOC families included biogenic compounds (oxygenated compounds, hydrocarbons, terpenes, and organosulfur compounds) and abiogenic compounds (aromatic hydrocarbons and halocarbons). Oxygenated compounds, particularly alcohols, were the most abundant compounds in all samples. With the use of odor index analysis and principal components analysis, the hydrothermal hydrolysis and aerobic fermentation units were clearly distinguished from the pre-treatment units, as characterized by their higher contributions to odorous nuisance. Methanthiol was the dominant odorant in the hydrothermal hydrolysis unit, whereas aldehyde was the dominant odorant in the aerobic fermentation unit. Terpenes, specifically limonene, had the highest level of propylene equivalent concentration during the monitoring periods. This concentration can contribute to the increase in the atmospheric reactivity and ozone formation potential in the surrounding air.     

Leader–member exchange and job performance: The effects of taking charge and organizational tenure

We theorized and tested the mechanisms by which leader–member exchange (LMX) quality is associated with job performance. The results obtained using 212 employee–supervisor pairs from eight Chinese companies indicated that LMX quality had an indirect and positive relationship with taking charge via psychological empowerment and had an indirect and positive relationship with job performance via taking charge. In addition, organizational tenure significantly moderated the relationship between taking charge and job performance, such that the positive effect of taking charge on job performance became weaker as organizational tenure increased. Furthermore, organizational tenure significantly moderated the indirect positive relationship between LMX quality and job performance via taking charge; the indirect effect became weaker as organizational tenure increased. These results suggest that organizations should encourage managers to develop high‐quality LMX with their subordinates, which may make them feel more empowered and engage in more taking charge, and result in better job performance. Copyright © 2014 John Wiley & Sons, Ltd.     

我国废弃电子电器产品的回收体系研究

分析了废弃电子电器产品的特点，介绍了国内外废弃电丰电器产品的回收处理现状，结合生产者责任延伸制度，从观念、法律、管理、企业、收费等方面对我国废弃电子电器产品回收体系的建设进行了探讨，并提出了建议。     

2种低射速下火炮膛内模块装药烤燃特性的对比与分析

目的 研究火炮多发连续射击后膛内模块装药的受热过程.方法 采用烤燃的思想建立模块装药留膛二维瞬态烤燃模型.以443 K为临界温度,求解火炮在2种低射速工况(以每分钟2、3发)下连续射击至药室内壁温度达到约443 K时的壁面温度分布,并以此为初始温度条件,对模块装药在膛内的烤燃过程进行数值模拟,对比分析2种低射速下火炮膛...     

炮孔轴向不同间隔方式的爆破地震效应研究

不同装药结构爆破的地震效应存在较大差异,对于间隔装药结构而言,当采用的间隔介质相同时,采用什么样的间隔方式的降震效果更好呢?对此,就底部间隔、中部间隔还是顶部间隔装药方式的地震效应进行了比较研究.综合比较地震振动幅值、频率和振动持续时间等主要因素,3种间隔方式中,孔底间隔装药结构的爆破地震效应最小,其次为孔上部间隔,再次为孔中部间隔.