基于制备超细复合含能材料的对置受限式撞击流反应器微观混合性能

由于对置受限式撞击流反应器较高的传热及混合效率，能够制备出粒径小、均匀且分布范围窄的超细颗粒。本文采用碘化物-碘酸盐平行竞争反应体系研究入射速度、结构尺寸对对置受限式撞击流反应器微观混合效果的影响规律，并将混合腔尺寸同等比例放大一倍进行对比研究。结果表明，随着入射速度的增大，离集指数减小，微观混合效果提高。喷嘴间距与喷嘴直径比的增大使得离集指数增大，微观混合效果降低。离集指数随着混合腔高度、混合腔出口尺寸的增大呈现先增大后减小的趋势，且混合腔高度对混合效果的影响较混合腔出口尺寸显著。将对置受限式撞击流反应器混合腔尺寸扩大一倍，离集指数增加到原来的2.4倍，微观混合效果显著下降，但是在较大入射速度下，两种结构的混合效果差距减小。研究结果可为纳米复合含能材料的制备提供高效、安全的技术支持。     

组合赋权的TOPSIS在冲击地压危险性评价中的应用

为了合理准确地评价煤矿冲击地压危险性,在现有评价冲击地压危险性实例的基础上,从煤矿地质因素和开采因素2个方面,选取10个主要的影响指标,利用熵权法和指标相关性权重法分别计算影响冲击地压危险性的各评价指标权重,再根据组合赋权的方法得出各指标的综合权重,构建基于逼近理想解理论的冲击地压危险性评价模型。以重庆砚石台煤矿为例,选取20组评价冲击地压危险性样本数据进行分析,确定评价冲击地压危险性的最优和最劣状况,然后计算出各个评价方案与最优和最劣状况的距离,最后综合最优与最劣距离,确定评价对象的相对贴近度。应用结果表明:评价结果与实际情况一致,且该模型相较其他模型的评价结果更加科学准确,表明该方法有良好的实用价值。     

乙醇汽油燃料特性对直喷增压乘用车性能影响研究

使用纯汽油与4种乙醇体积分数为10%的乙醇汽油,在一辆缸内汽油直喷乘用车上研究不同燃料对整车性能的影响。试验结果表明:在新欧洲驾驶循环下,燃用乙醇汽油会增加汽车运行时的百公里油耗,但燃用乙醇汽油汽车的当量油耗则可以低于纯汽油汽车的油耗,说明燃用乙醇汽油燃料的汽车可以实现更高的热效率、更低的碳排放、更低的颗粒物排放和更良好的加速性能。5种燃料中,随芳烃含量升高,汽车油耗、颗粒数、NO_x排放整体会呈现上升趋势。综合性能来看,通过燃料优化可以使乙醇汽油高效清洁地应用于整车,但在低车速、冷起动工况下因发动机运转温度较低,其CO排放比纯汽油要高,HC排放比纯汽油低。     

基于地表温度和植被指数的黑龙江省旱情遥感动态监测

干旱灾害是一种影响范围广、时间跨度大的自然灾害,对社会经济发展尤其是给农业生产造成重大损失。遥感技术具有观测空间尺度大、实时性强的特点,有利于大范围、实时、动态的旱情监测。利用MODIS的LST和NDVI遥感数据,依托站点实测土壤含水率数据,分析土壤含水率与地表温度和植被指数之间的关系,考虑土壤类型,构建温度植被多项式模型,进行表层土壤水分反演,基于此开展2018年3~7月黑龙江省旱情遥感监测应用研究。监测结果显示,监测期内黑龙江省经历了两次规模较大的干旱过程,干旱的核心区域为黑龙江省西南部区域,与实际情况相吻合。研究表明,考虑土壤类型的温度植被多项式模型对旱情遥感监测具有良好的应用效果。     

Food insecurity and nutrition index: Disaggregation and evidence for Brazilian states

Food security and nutrition is a multidimensional theme consisting of three pillars: food access, availability, and sufficiency. Given food security and nutrition's extent, its measures are usually limited. To address these limitations, this paper proposes the creation of a disaggregated food insecurity index for Brazilian states, with the three dimensions in mind. The results show that while food availability elevates the average of the index, the sufficiency still is a problem. Even though the distribution of and access to food in Brazil has increased in the last years, it was not combined with policies that guarantee its safety and quality, reinforcing the need for specific interventions considering regional particularities.     

基于双谱特征的行星齿轮箱故障诊断方法

为了研究行星齿轮箱齿面磨损全生命周期实验的退化过程,使用了可以抑制高斯噪声和对信号中产生的频率耦合进行解耦的双谱方法去进行故障特征提取,提出了两个基于双谱的特征指标,双谱熵以及非高斯强度,并通过特征指标评价方法去检验其指标性能。结果表明基于双谱熵具有良好的指标性能,而且对于行星齿轮箱齿面磨损的早期微弱故障十分敏感,适用于行星齿轮箱齿面磨损的故障诊断。     

Thermal history and its implications: A case study for ion exchange

Glasses containing monovalent species can be chemically strengthened by the replacement of smaller ions in the glass with larger external ions in the near glass surface. This type of ion exchange puts glass surface under high compressive stress (CS). Glass mainly fails from tension with the presence of surface flaws. Chemical strengthening can change the stress at the flaw tip from tension to compression and further stop the flaw from propagating. Glass damage resistance is therefore significantly improved. For the same glass composition, glass thermal histories can affect the magnitude and depth of the CS generated during ion exchange. In this study, the impact of thermal history on glass physical properties and ion exchange attributes in one alkali-containing glass formed by fusion draw process was investigated. Multiple thermal treatments were done to rewrite the glass thermal histories. Glass density, refractive index, and ion-exchange properties as a function of the thermal treatment were studied. It is concluded that ion exchange-related properties change dramatically with the glass thermal history.     

NDQ催化剂在400 kt/a Spheripol聚丙烯工业装置上的应用

以三乙基铝为助催化剂,环已基甲基二甲氧基硅烷为外给电子体,使用NDQ催化剂在400 kt/a的Spheripol聚丙烯工业装置上试生产了注塑专用聚丙烯HA8012和HP-M12。结果表明:试生产期间,装置运行平稳,聚合工艺参数可控可调,聚丙稀细粉含量低;采用NDQ催化剂生产的HA8012和HP-M12具有较宽的相对分子质量分布(6.0~6.5)、较低的二甲苯可溶物含量(质量分数为1.5%~2.0%)、较高的拉伸强度(大于38 MPa)和弯曲模量(1.8~2.2 GPa)。     

Classification and identification of gas–liquid dispersion states in a jet bubbling reactor

Three gas–liquid dispersion states including flooding, loading, and complete dispersion are observed sequentially in a jet bubbling reactor with an increase of the liquid jet velocity at the nozzle outlet (u_j). The gas–liquid dispersion states are identified through the slope (k) of the curve of fluctuation distribution index (FI) versus u_j as follows: (a) under the flooding, k = 0; (b) under the loading, k > 0; (c) under the complete dispersion, k < 0. In particular, the u_j at the transition points from flooding to loading and from loading to complete dispersion are referred to flooding jet velocity (u_jf, the transition point between k = 0 and k > 0) and complete dispersion jet velocity (u_jcd, the transition point from k > 0 to k < 0), respectively. The average relative deviations of the u_j at the transition points obtained through the acoustic emission measurement and visual observation are less than 5%.     

催化裂化催化剂形貌分析方法的建立

结合显微镜观察,通过分析毫米级颗粒、微米级Duke粒子及催化裂化催化剂,研究动态数字图像分析仪CamsizerX2分析颗粒形貌的合理准确性。考察分散方式、分散压力和记录颗粒数量因素的影响,建立了催化裂化催化剂球形貌分析方法。