甲烷化技术国产化研究进展

甲烷化是焦炉气制天然气、煤制天然气生产流程的关键步骤,为打破国外技术垄断,国内研究机构积极进行技术开发。系统梳理了甲烷化技术的国产化研究进展,分析了焦炉气甲烷化技术的应用现状,探讨煤制天然气甲烷化技术的应用前景,并就降低首次工程应用风险提出几点建议。国内甲烷化技术已经实现广泛开发,焦炉气甲烷化技术成功实现工业化应用,其国内市场占有率高于国外技术。煤制天然气甲烷化技术已成功开发,工业化应用前景广阔,首次工程应用时应注重经验借鉴、安全分析及设备选型等。     

Synchronous Growth of High‐Quality Bilayer Bernal Graphene: From Hexagonal Single‐Crystal Domains to Wafer‐Scale Homogeneous Films

The precise control of the domain structure, layer thickness, and stacking order of graphene has attracted intense interest because of its great potential for nanoelectronics applications. Much effort has been devoted to synthesize semiconducting Bernal (AB)‐stacked bilayer graphene because of its tunable band structure and electronic properties that are unavailable to single‐layer graphene. However, fast growth of large‐scale bilayer graphene sheets with a high AB‐stacking ratio and high mobility on copper poses a tremendous challenge, which has to overcome the self‐limiting effect. This study reports a low‐cost but facile method to rapidly synthesize bilayer Bernal graphene by atmospheric pressure chemical vapor deposition using polystyrene as the feedstock. The bilayer graphene grains and continuous film obtained are of high quality and exhibit field‐effect hole mobilities as high as 5700 and 2200 cm² V^?1 s^?1 at room temperature, respectively. In addition, a synchronous growth mechanism of bilayer graphene is revealed by monitoring the growth process, resulting in a high surface coverage of nearly 100% for a near‐perfect AB‐stacking order. This new synthesis route is significant for industrial application of bilayer graphene and investigation of the growth mechanism of graphene by the chemical vapor deposition process.     

Solution‐Processed Nanoporous Organic Semiconductor Thin Films: Toward Health and Environmental Monitoring of Volatile Markers

Porous materials are ubiquitous in nature and have found a wide range of applications because of their unique absorption, optical, mechanical, and catalytic properties. Large surface‐area‐to‐volume ratio is deemed a key factor contributing to their catalytic properties. Here, it is shown that introducing tunable nanopores (50–700 nm) to organic semiconductor thin films enhances their reactivity with volatile organic compounds by up to an order of magnitude, while the surface‐area‐to‐volume ratio is almost unchanged. Mechanistic investigations show that nanopores grant direct access to the highly reactive sites otherwise buried in the conductive channel of the transistor. The high reactivity of nanoporous organic field‐effect transistors leads to unprecedented ultrasensitive, ultrafast, selective chemical sensing below the 1 ppb level on a hundred millisecond time scale, enabling a wide range of health and environmental applications. Flexible sensor chip for monitoring breath ammonia is further demonstrated; this is a potential biomarker for chronic kidney disease.     

SDICA方法在单通道信号故障分类中的研究

提出了一种针对工程单通道信号的子带分解独立分量分析(subband decomposition independent component analysis,简称SDICA)故障分类方法。利用经验模态分解方法(empirical mode decomposition,简称EMD)得到的多个基本模式分量作为子带信号,对子带信号进行独立分量分析(independent component analysis,简称ICA),在ICA方法过程中提取了分离过程特征中产生的残余互信息值,在估计子带信号中计算各自的近似熵值,并把残余互信息和近似熵值作为特征参数,输入广义回归神经网络实现故障分类。SDICA方法在单通道信号故障分类中引入了ICA理论,成功实现了工程单通道轴承信号3种故障高精度的识别,验证了具有良好表征故障能力的残余互信息值和估计子带近似熵能够成为故障分类的重要参数。     

开口截面钢-混凝土组合梁弯扭性能的理论分析与试验研究

对 3根不同扭弯比的开口截面组合梁弯扭进行试验分析得出组合梁的弯型和扭型两种破坏形态。将组合梁划分成三维 8结点实体单元 ,用有限元方法对组合梁在弯扭作用下的工作性能进行了弹性理论分析 ,建立了弯扭强度M -T相关公式。通过编制组合梁截面的弯矩 -曲率全过程计算程序 ,得出了混凝土翼板受力与截面弯矩之间的关系 ,从而阐明了弯扭共同作用下组合梁的受力机理 ,建立了极限状态的弯扭强度M -T相关公式 ,并分析了组合梁截面参数对相关曲线的影响。     

钢-混凝土组合梁的疲劳问题

到目前为止 ,我国在钢 -混凝土组合梁疲劳方面的研究工作仍然较少 ,为了给钢 -混凝土组合梁的疲劳设计提供参考和依据 ,对国际上有关钢 -混凝土组合梁疲劳的试验研究、计算方法以及相应规范进行了综述和分析评价 ,可供在进行组合梁疲劳方面的试验研究、设计和制订规范时借鉴和参考。     

城市产业类历史建筑及地段的改造再利用

在城市发展历程上,产业类建筑及地段具有功不可没的历史地位,由其所产生的独特的“产业景观”是城市重要组成部分之一。本文较系统地阐述和剖析了世界城市产业类历史建筑及地段的基本概念、分类、再开发利用的方式和改造设计的技术措施。     

胥虹桥上部结构计算分析

胥虹桥为三孔刚架拱桥，主孔净跨为６０ｍ，全桥长度为１５５．９８ｍ，该桥于１９９２年６月建成，从竣工后延续至今，相继出现桥面裂缝，拱肋开裂，墩台变位，桥面下沉等病害。本文着重分析该桥病害发生的上部结构的原因。     

深圳华润中心月牙形中庭大跨钢-混凝土组合结构

本文简要地介绍了深圳华润中心工程月牙形中庭大跨钢-混凝土组合结构设计。工程实践表明,钢-混凝土组合梁用于大跨结构,具有显著的技术经济效益和社会效益。     

高强混凝土配合比正交设计方法

采用Cement-FA(Fly Ash）-SF（Silica Fume）三元胶凝材料系统及正交设计手段配制高强混凝土，以混凝土的抗压强度为指标，利用数学软件SAS统计分析系统，定量地分析胶凝材料总量，矿物掺和料比例、水胶比、砂率等因素及其不同的掺量水平对混凝土强度发展历程的影响，结果表明，正交设计的分析结果与试验结果有良好的一致性，可为高强混凝土的配合比设计提供方向与定量化分析手段。