载锌NaY分子筛对FCC汽油吸附脱硫性能的影响

采用液相离子交换法将锌离子负载到NaY分子筛上,得到ZnY分子筛脱硫吸附剂。考察了锌离子负载浓度和不同焙烧温度对ZnY分子筛吸附脱硫性能的影响。研究脱硫实验中吸附温度和吸附空速对FCC汽油脱硫性能的影响,样品中的硫含量通过微库仑综合分析仪进行测定。结果表明,Zn(NO₃)₂负载浓度0.30 mol·L^-1、焙烧温度500 ℃、吸附温度30 ℃和吸附空速0.5 h^-1条件下对吸附脱硫性能最有利,脱硫率超过80%。考察两种方法对吸附剂进行再生。     

Gradient Based Aura Feature Extraction for Coral Reef Classification

Wireless Personal Communications - Millimeter wave (mmWave) has been regarded as a candidate cellular band for future 5G networks. It exhibits an extension for current cellular bands, where its...     

Comparison of black smoke and PM2.5 levels in indoor and outdoor environments of four European cities

Recent studies on separated particle-size fractions highlight the health significance of particulate matter smaller than 2.5 microm (PM2.5), but gravimetric methods do not identify specific particle sources. Diesel exhaust particles (DEP) contain elemental carbon (EC), the dominant light-absorbing substance in the atmosphere. Black smoke (BS) is a measure for light absorption of PM and, thus, an alternative way to estimating EC concentrations, which may serve as a proxy for diesel exhaust emissions. We analyzed PM2.5 and BS data collected within the EXPOLIS study (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) in Athens, Basel, Helsinki, and Prague. 186 indoor/outdoor filter pairs were sampled and analyzed. PM2.5 and BS levels were lowest in Helsinki, moderate in Basel, and remarkably higher in Athens and Prague. In each city, Spearman correlation coefficients of indoor versus outdoor were higher for BS (range rspearman: 0.57-0.86) than for PM2.5 (0.05-0.69). In a BS linear regression model (all data), outdoor levels explained clearly more of indoor variation (86%) than in the corresponding PM2.5 model (59%). In conclusion, ambient BS seizes a health-relevant fraction of fine particles to which people are exposed indoors and outdoors and exposure to which can be assessed by monitoring outdoor concentrations. BS measured on PM2.5 filters can be recommended as a valid and cheap additional indicator in studies on combustion-related air pollution and health.     

Resilient Distributed Computing

A control abstraction called atomic action is a powerful general mechanism for ensuring consistent behavior of a system in spite of failures of individual computations running in the system, and in spite of system crashes. However, because of the ``all-or-nothing' property of atomic actions, an important amount of work might be abandoned needlessly when an internal error is encountered. This paper discusses how implementation of resilient distributed systems can be supported using a combination of nested atomic actions and stable checkpoints. Nested atomic actions form a tree structure. When an internal atomic action terminates, its results are not made permanent until the outermost atomic action commits, but they survive local node failures. Each subtree of atomic actions is recoverable individually. A checkpoint is established in stable storage as part of a remote request so that results of such a request can be reclaimed if the requesting node fails in the meantime, The paper shows how remote procedure call primitives with ``at-most-once' semantics and recovery blocks can be built with these mechanisms.     

应用范围不断扩大的弹力纱整经机

描述了德国利巴公司最近推出的两款改进型弹力纱整经机,型号是EXPANDER 23E-560 NCL Ⅱ（图1）和EXPANDER 24E-1280 NCL Ⅱ,分条经轴盘直径为762 mm（30 in）的23E-NCL Ⅱ型分条整经机的幅宽达560 mm,24E-NCL Ⅱ型可达1280 mm。最高整经速度可达700 m/min,是筒子最大运转速度的两倍。纱线的最大预牵扯伸比率可达300%,在分条经轴上的最终牵伸率最高可达100%。     

P, As, Sb, Mo, and other elements in sedimentary Fe/Mn layers of Lake Baikal

Distinct layers with accumulated iron and manganese oxyhydroxides are found in the recent sediments of Lake Baikal (Siberia). In the South and Central Basins, these concretions accumulate close to the sediment-water interface. In northern Lake Baikal and the area of Academician Ridge, however, massive Fe/Mn crusts are formed within several thousand years at redox fronts 10 to 15 cm below the sediment surface. In some places, precipitated iron and manganese oxyhydroxides are spatially separated. The patterns are a result of secondary iron and manganese oxide precipitation. This natural long-term experiment allows the analysis of competitive adsorption and coprecipitation of trace elements with iron and manganese oxides in sediments. Background concentrations in the sediment of oxoanions (P, As, Sb, Mo); of trace metals (Cr, V, Cu, Zn, Cd, Pb); and of Mg, Ca, Sr, La, Ce, Pr, Nd, and Sm were analyzed by inductively coupled plasma mass spectrometry. Despite the differences in catchment geology of the many tributaries, they are remarkably uniform in sediment cores from different basins of Lake Baikal. Enrichment factors of P and As within Fe crusts revealed concentrations up to 14 and 58 times higher than the background, respectively. No enrichment of P and As was found in the Mn layers. By contrast, Mo accumulated exclusively in the Mn layer with up to 35-fold enrichment. Sb was only slightly enriched in both the Fe and the Mn layers. Among the trace metals studied, only Cd was found at elevated concentrations with a preference for the Mn layer. Ca and Sr were correlated with both Fe and Mn accumulations. The study quantifies the well-known specific adsorption and coprecipitation of P and As at authigenic iron oxides and of Mo on manganese oxides. In addition, the enrichment of Cd at manganese oxides in contrast to the conservative behavior of Zn and Pb reveals highly selective accumulation processes.