基于MATLAB的GPS周跳探测与修复

在GPS观测过程中,信号会受到遮挡等原因发生跳变现象,引起很大误差甚至是粗差,为了解决这一问题,文中利用MATLAB软件,根据电离层残差法和Melbourne-Wübbena组合法的优缺点,结合这两种方法进行GPS载波相位观测值的周跳探测,然后根据周跳探测结果进行修复,结果表明:利用组合方法编制的MATLAB周跳探测与修复的程序能很好的探测和修复GPS周跳.     

The effect of alkali metal oxide on the properties of borosilicate fireproof glass: Structure,thermal properties,viscosity, chemical stability

The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R₂O–CaO–B₂O₃–SiO₂) systematically. Because the glass would emulsify when Li₂O was added to the glass batch, this article did not discuss Li₂O. The results showed that when the amount of Na₂O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na₂O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased.     

石峡遗址玉琮形制与纹饰设计流变解读

通过梳理石峡遗址玉琮不同阶段形制与纹饰设计的变化,以及良渚文化和同时期其他地区玉琮的形制、纹饰和功能的分析,发现广东境内出土的玉琮与良渚文化关系极为密切,石峡遗址的多节玉琮更是直接来自于太湖地区,而那些纹饰设计出现颠倒或发生较大改变者应为本地仿制品。龙山时代,玉琮虽然传播和辐及的范围十分广泛,但是在大部分地区其功能都发生了变化,只有广东地区的玉琮仍最大程度地坚守着传统与信仰。石峡遗址玉琮形制与纹饰设计流变,所反映出的这种文化传播方式、接收程度与再创作,突出地体现了一种强势文化在对外传播和扩散的过程中,因地因时而制宜。这或许可以提示我们,利用传统文化元素进行再设计,欲意达到传统与现代的融合与契合,更理应如此。     

Multi-grained encoding and joint embedding space fusion for video and text cross-modal retrieval

Multimedia Tools and Applications - Video-text cross-modal retrieval is significant to computer vision. Most of existing works focus on exploring the global similarity between modalities, but...     

Laser-assisted preparation of monolithic acidic catalysts for biomass conversion

5-(Hydroxymethyl)furfural (5-HMF) is a vital platform molecule from which a variety of high-value-added fine chemicals and polymerizable monomers can be prepared. The use of solid acids to catalyze the conversion of biomass into 5-HMF is environmentally friendly and economical. However, exploiting the high yield of 5-HMF in a highly concentrated reactant system is challenging. Herein, we present a laser-assisted method for preparing highly acidic monolithic acidic catalysts. A monolithic acidic catalyst based on metal Zr sheets was synthesized and used to catalytically convert 30 wt% fructose into 5-HMF (conversion rate: 96%; yield: 95%). The catalyst was immediately separated from the reaction solution by direct removal at the end of the reaction. Catalytic efficiency was largely unaffected after 10 cycles of use, and the same catalytic efficiency was observed after laser-regeneration, highlighting the potential industrial applicability of the developed catalyst.     

Trimetallic NiFeCr-LDH/MoS2composites as novel electrocatalyst for OER

The development of efficient and stable oxygen evolution reaction (OER) catalysts is an ongoing challenge. In order to solve the problem of low oxygen evolution efficiency of the current OER catalysts, a novel material was synthesized by the incorporation of NiFeCr-LDH and MoS₂, and its structural and electrochemical properties were also investigated. The introduction of MoS₂ improves the electrochemical performance of NiFeCr-LDH. The polarization curve shows that the potential of composite material is only 1.50 V at a current density of 10 mA cm^?2, which is far superior to commercial precious metal catalysts. In addition, the stability experiment shows that the composite material has excellent stability, and the current density has little change after 500 cycles. Furthermore, we found that some metal ions, such as Ni, Cr and Mo, exist in the form of high valence on the surface of NiFeCr-LDH@MoS₂, which is also conducive to the occurrence of oxygen evolution reaction.     

某大型工业运输钢桁架通廊振动测试分析

皮带机运输通廊钢桁架作为工业运输通道最为常用的大跨结构形式,因其结构存在自身稳定性能差、刚度小、质量轻等特点,在皮带机高速运营过程中结构易产生振动.为确保运营安全,该文以某皮带机运输通廊钢桁架为例,对该通廊结构在各种运行工况下进行现场振动测试并结合理论分析找出结构振动原因,同时对其运行状态安全性作出验算分析,为进一步进行结构减振控制研究及加固处理提供依据.     

Cu-assisted induced atomic-level bivalent Fe confined on N-doped carbon concave dodecahedrons for acid oxygen reduction electrocatalysis

Atomically dispersed transition metals anchored on N-doped carbon have been successfully developed as promising electrocatalysts for acidic oxygen reduction reaction (ORR). Nonetheless, how to introduce and construct single-atomic active sites is still a big challenge. Herein, a novel concave dodecahedron catalyst of N-doped carbon (FeCuNC) with well confined atomically dispersed bivalent Fe sites was facilely developed via a Cu-assisted induced strategy. The obtained catalyst delivered outstanding ORR performance in 0.5 M H₂SO₄ media with a half-wave potential (E_1/2) of 0.82 V (vs reversible hydrogen electrode, RHE), stemming from the highly active bivalent Fe-N_x sites with sufficient exposure and accessibility guaranteed by the high specific surface area and curved surface. This work provides a simple but efficient metal-assisted induced strategy to tune the configurations of atomically dispersed active sites as well as microscopy structures of carbon matrix to develop promising PGM-free catalysts for proton exchange membrane fuel cell (PEMFC) applications.     

建筑工程地下停车场加固改造施工技术

在高层建筑中,地下工程很常见.在当今的建筑工程中,地下工程的施工包括大型设备房、机房、外墙套管等项目.由于高层建筑自身楼层较高,对建筑体的地下室的承载力要求较高,为了保证高层建筑的稳定性,需要对高层建筑地下室结构采取一定的加固措施.结合实例,主要分析了地下停车场工程新旧结构交接节点、地下室剪力墙、梁增大截面等加固改造施工技术,旨在帮助项目提高策划能力,增强过程管控能力,提升实施阶段的精细化管理水平.     

Waste sugar solution polymer-derived N-doped carbon spheres with an ultrahigh specific surface area for superior performance supercapacitors

Waste sugar solution (WSS), a waste by-product of manufacturing vitamin C, contains abundant waste acids and organics. In this work, a N/O-enriched copolymer was synthesized via a facile polymerization via the hydrogen bonding of O-containing functional groups and melamine and the crosslinking of aldehyde groups. Subsequently, N-doped carbon spheres were prepared by a typical carbonation/activation method. Remarkably, benefiting from an ultrahigh specific surface area (3612 m²/g) and rich heteroatom content (4.3% for N, 8.8% for O), the carbon spheres deliver a high specific capacitance of 387 F/g at 50 mA/g and 283 F/g at 5 A/g with 6 M KOH in two-electrode system. The assembled symmetric electric double-layer capacitor exhibits high energy density of 10.83 Wh/kg at 11.10 W/kg. This research provides a facile method for preparing N/O-doped carbon spheres by WSS, and confirms the excellent electrochemical performance of WSS-derived carbons in energy storage applications.