Corrosion resistance evaluation of highly dispersed MgO-MgAl2O4-ZrO2 composite and analysis of its corrosion mechanism: A chromium-free refractory for RH refining kilns

The corrosion resistance behavior of a highly dispersed MgO-MgAl₂O₄-ZrO₂ composite refractory material is examined by testing with high-basicity and low-basicity RH (Ruhrstahl-Hereaeus) slags. The composite material exhibits greater resistance to the RH slags than the traditional MgO-Cr₂O₃ composite, MgO-ZrO₂ composite, and MgO-MgAl₂O₄-ZrO₂ composite. On the basis of the microstructural analysis and mechanisms calculations, the corrosion resistance behavior of the MgO-MgAl₂O₄-ZrO₂ composite is attributable to its highly dispersed structure, which helps protect the high activity of ZrO₂. When in contact with the slag, ZrO₂ reacts with CaO to form the stable phase CaZrO₃, which protects MgAl₂O₄ against corrosion, thereby enhancing the corrosion resistance of the composite.     

Discovery of marine fossils in the upper part of the Permian Linxi Formation in Lopingian, Xingmeng area, China

Two important geological issues have a long history of debate in the Xingmeng area. The first concerns the final closure of the North China plate, Siberia plate and several intermediate massifs in the area, and the other con- cerns the folding and lifting of the Xingmeng Trough. Dis- agreements arise because of issues involving the tectonic- palaeogeographical environment of the Upper Permian deposits of the Linxi Formation. The Linxi Formation （Upper Permian） is generally considered to be either an exclusively continental deposit or separated into marine- terrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period. However, in this study, large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia. At the same time, abun- dant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Tao- huayingzi Formation from the Taohuayingzi section in Ar Horqin Banner, and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county, Jilin Province. These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian. This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes chan- ges in the approach towards research, exploration and development of oil and gas, shale gas （oil）, and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.     

Evolution of stomatal and trichome density of the Quercus delavayi complex since the late Miocene

A fossil oak species,Quercus tenuipilosa Q.Hu et Z.K.Zhou,is reported from the upper Pliocene Ciying Formation in Kunming,Yunnan Province,southwestern China.The establishment of this species is based on detailed morphologic and cuticular investigations.The fossil leaves are elliptic,with serrate margins on the apical half.The primary venation is pinnate,and the major secondary venation is craspedodromous.The tertiary veins are opposite or alternate-opposite percurrent with two branches.The stomata are anomocytic,occurring only on the abaxial epidermis.The trichome bases are unicellular or multicellular.The new fossil species shows the closest affinity with theextant Q.delavayi and the late Miocene Q.praedelavayi Y.W.Xing et Z.K.Zhou from the Xiaolongtan Formation of the Yunnan Province.All three species share similar leaf morphology,but differ with respect to trichome base and stomatal densities.Q.tenuipilosa.Q.praedelavayi,and Q.delavayi can be considered to constitute the Q.delavayi complex.Since the late Miocene,a gradual reduction in trichome base density has occurred in this complex.This trend is the opposite of that of precipitation,indicating that increased trichome density is not an adaptation to dry environments.The stomatal density(SD)of the Q.delavayi complex was the highest during the late Miocene,declined in the late Pliocene,and then increased during the present epoch.These values show an inverse relationship with atmospheric CO_2 concentrations,suggesting that the SD of the Q.delavayi complex may be a useful proxy for reconstruction of paleo-CO_2 concentrations.     

Stratigraphy and age of the Daohugou Bed in Ningcheng, Inner Mongolia

Recent fieldwork has extended the distribution of the Daohugou Bed deposits from the Daohugou Village to its several neighboring areas. The fossil-bearing Daohugou deposits uncomformably overlie complex bedrocks, and comprise three major parts. The red shales in the lower part were misidentified as belonging to the Tuchengzi Formation. Field excavation has indicated that the shales of upper part of the bed are the major fossil-bearing horizon. Due to strong tectonic activities, sediments were often folded with the sequences inverted in the region. Some newly recognized contacts between the Daohugou Bed and the volcanic rocks showed that the ignimbrite of the Tiaojishan Formation （159-164 Ma） underlies the Daohugou deposits, rather than overlying the latter as previously proposed. Thus, the age of the Daohugou deposits should be younger than the age of the ignimbrite, and thus it was incorrect to correlate the Daohugou Bed with the Middle Jurassic Jiulongshan Formation. Although biostratigraphic studies based on conchostracans and insects support a Middle Jurassic-early Late Jurassic age for the Daohugou deposits, vertebrate fossils such as Liaoxitriton, Jeholopterus and feathered maniraptorans show much resemblance to those of the Yixian Formation. In other words, despite the absence of Lycoptera, a typical fish of the Jehol Biota, the Daohugou vertebrate assemblage is closer to that of the Early Cretaceous Jehol Biota than to any other biota. We propose that the Daohugou fossil assemblage probably represents the earliest evolutionary stage of the Jehol Biota based on both vertebrate biostratigraphy and the sedimentological and volcanic features which suggest the Daohugou deposit belongs to the same cycle of volcanism and sedimentation as the Yixian Formation of the Jehol Group.     

内抹调湿砂浆外墙吸放湿特性及对负荷影响分析

本文从建筑围护结构节能出发,以内抹WSE（木质纤维Wood fibre、海泡石Sepiolite、膨胀珍珠岩Expanded perlite）基复合调湿保温砂浆外墙为研究对象,将其与内抹普通砂浆外墙对比,分析吸放湿特性及其对负荷的影响. 研究使用COMSOL Multiphysics有限元软件的建筑材料热湿耦合模型,分析环境湿度变化与外墙之间的湿迁移变化,以及与外墙的传热传质. 以夏热冬冷典型气候地区长沙为例,分析内抹WSE基复合调湿保温砂浆外墙的负荷及潜热负荷占比,同时选取夏热冬暖地区广州和寒冷地区北京对比分析外墙的全年能耗. 研究发现,内抹WSE基复合调湿保温砂浆外墙的吸放湿速率远大于内抹普通砂浆的外墙,并能长时间保持高速的吸放湿状态,同时比内抹普通砂浆墙体节省22.31%~23.85%的全年负荷. 墙体在吸湿过程中,温升与吸湿速率能力体现出一致性,表明墙体内表面湿迁移对温度有着重要影响,并且湿迁移越大对温度影响越大. 墙体在放湿过程中,温度迅速下降是放湿速率快的表现. 内抹WSE基复合调湿保温砂浆墙体具有优良的吸放湿特性和节能潜力,可用于建筑围护结构节能.     

盐酸浸泡后的铁在空气中氧化及缓蚀剂防护作用的穆斯堡尔谱研究

用内转换电子穆斯堡尔谱(CEMS)分析了铁经盐酸或加有缓蚀剂的盐酸(缓蚀盐酸)浸泡后在空气中的氧化物,以及盐酸中的缓蚀剂对浸泡后铁在空气中氧化的防护作用.结果表明,盐酸或缓蚀盐酸浸泡后的铁在空气中的氧化物主要是γ-FeOOH,有少量β-FeOOH;盐酸中缓蚀剂对浸泡后的铁在空气中氧化具有防护作用.而且在盐酸中对铁的缓蚀性能较好,在空气中对铁的防氧化性能也较好.最后对缓蚀剂的防氧化作用机理进行了讨论.     

Symbols detection for frequency-selective V-BLAST OFDM systems

1.INTRODUCTION TheverticalBellLabslayeredspace time(V BLAST)architecture[1]isonemostpromisingspace timecoding(STC)technique.Theprovisioningca pacityoftheV BLASTarchitecturecanmorenear thetheoreticalupper limitofchannelcapacity[2].Therefore,quiteanumberofresearchersproposedto deploytheV BLASTarchitectureinwirelesslocal loop(WLL)andwirelesslocalareanetwork(WLAN)[3].Conventionally,themultiple inputmultiple out put(MIMO)wirelesschannelsintheV BLASTar chitectureareassumedtobefl…     

Robust H∞ Filter Design for a Class of Uncertain Linear Systems with Time—delayed Measurement

A robust H∞ approach to filtering for a class of uncertain linear systems with time-delayed measurement is investigated.The parameter uncertainties are described by real time-varying norm-bounded form.A methodology is developed for designing linear filters such that the filtering process remains robustly stable and the transfer function from the disturbance inputs to error state outputs meets the prescribed H∞-bound constraints.The filter can be obtained and parameterized by solving two Riccati equations based on the lemma of robust stability for control system with delay.Simulation example proves the method to be effective and feasible.     

Cortical Bone Model with a Microcrack under Tensile Loading

The fracture mechanics of cortical bone has received much attention in biomedical engineering.It is a fundamental question how the material constants and the geometric parameters of the cortical bone affect the fracture behavior of the cortical bone.In this work,the plane problem for cortical bone with a microcrack located in the interstitial tissue under tensile loading was considered.Using the solution for the continuously distributed edge dislocations as Green ’ s functions,the problem was fo...     

Implementation of Abstract MAC Layer Under Jamming

In the past decades, with the widespread implementation of wireless networks, such as the Internet of Things, an enormous demand for designing relative algorithms for various realistic scenarios has arisen. However,with the widening of scales and deepening of network layers, it has become increasingly challenging to design such algorithms when the issues of message dissemination at high levels and the contention management at the physical layer are considered. Accordingly, the abstract medium ac...