上升气泡内气溶胶沉降机理研究

气溶胶池洗过滤是反应堆严重事故中去除放射性源项的重要手段。本文以严重事故条件下上升气泡中气溶胶的滞留过程为背景，设计搭建了可视化单气泡鼓泡实验装置。通过该装置研究了气溶胶在上升气泡中的沉降效率，并与MELCOR中的气溶胶沉降模型计算结果进行了对比。结果表明，气溶胶沉降效率对气泡尺寸的变化较为敏感，当气体流量大于0.1 L/min时，气泡等效直径迅速增加，相应的气溶胶沉降效率快速降低；与MELCOR模型计算结果的对比表明，两者在总体趋势上呈现出较好的一致性，但计算结果低估了液相对气溶胶的实际去除能力，导致这种偏差的主要原因是气泡在上升过程中存在无规则的晃动以及气液界面的波动。     

A Student's t-based density peaks clustering with superpixel segmentation (tDPCSS) method for image color clustering

Image color clustering is a basic technique in image processing and computer vision, which is often applied in image segmentation, color transfer, contrast enhancement, object detection, skin color capture, and so forth. Various clustering algorithms have been employed for image color clustering in recent years. However, most of the algorithms require a large amount of memory or a predetermined number of clusters. In addition, some of the existing algorithms are sensitive to the parameter configurations. In order to tackle the above problems, we propose an image color clustering method named Student's t-based density peaks clustering with superpixel segmentation (tDPCSS), which can automatically obtain clustering results, without requiring a large amount of memory, and is not dependent on the parameters of the algorithm or the number of clusters. In tDPCSS, superpixels are obtained based on automatic and constrained simple non-iterative clustering, to automatically decrease the image data volume. A Student's t kernel function and a cluster center selection method are adopted to eliminate the dependence of the density peak clustering on parameters and the number of clusters, respectively. The experiments undertaken in this study confirmed that the proposed approach outperforms k-means, fuzzy c-means, mean-shift clustering, and density peak clustering with superpixel segmentation in the accuracy of the cluster centers and the validity of the clustering results.     

Comprehensive branching analysis of polyethylene by combined fractionation and thermal analysis

Linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) differ significantly in their branching types and branching distributions. For a comprehensive analysis, preparative temperature rising elution fractionation and/or preparative molar mass fractionation are used to fractionate typical LLDPE and LDPE bulk resins into narrowly distributed fractions. The chain structures of the bulk resins and their fractions are further analysed using SEC, crystallization analysis fractionation, DSC and high‐temperature HPLC to provide detailed information on short chain branching in LLDPE and long chain branching in LDPE. For LDPE it is shown that the multiple fractionation approach is a powerful source of sample libraries that may have similar molar masses and different branching structures or alternatively similar branching but different molar masses. The analysis of these library samples by thermal analysis provides a much deeper insight into the molecular heterogeneity of the samples compared to bulk sample analysis. © 2018 Society of Chemical Industry     

关于<高耸结构设计规范>修编若干问题的探讨

本文根据 10年来《高耸结构设计规范》(GBJ135 90 )的使用情况和科学研究基础 ,结合国家基本规范新一轮的修编状况 ,提出了此次《高耸结构设计规范》修编需修改和补充的若干条款     

导轨式电动整体爬模施工技术

导轨式电动整体爬模是适用于高层建筑的新型架体体系，是一种工效高、劳动强度低、整体性好、安全可靠、适用性强的施工技术，特别是当建筑物高度在80m以上时，经济性更为显著。     

Rising sludge in secondary settlers due to denitrification

High suspended solids concentrations in settler effluents can be caused by rising sludge, which is the effect of flotation of solids by nitrogen gas resulting from biological denitrification. Many factors influence the nitrogen gas bubble evolution. The most important factor is the rate of biological denitrification. Factors like nitrogen gas solubility and oxygen concentration in settler influent only play a minor role. The hydraulic retention time in the bottom part of the settler is, for all practical purposes, so high that sufficient nitrogen gas will be generated at temperatures above 20°C, if the nitrate content in the influent to the settler is above the critical one. For temperatures around 20°C the critical nitrate-nitrogen concentration is 6–8 g NO₃⁻-N/m³. The best measure in order to avoid rising sludge is to denitrify the wastewater in the treatment process ahead of the settler.     

用虚拟仪器技术检测混凝土的绝热温升

介绍了新兴计算机虚拟仪器技术在混凝土绝热温升检测中的应用，包括虚拟仪器各组成部分的设计原理及仪器主要部件的情况，以及采用虚拟仪器检测混凝土绝热温升的试验结果。     

确定混凝土温度特性多参数的试验与反演分析

确定砼绝热温升、表面散热系数试验需昂贵的专用设备 ,另外 ,因试验和工程现场环境差异大 ,试验结果存在较大误差。提出一种新思路 ,采用试验和反演分析相结合的方法 ,既能同时获得多个温度特性参数 ,又使试验设备相对简便 ,很易推广应用     

基于回波峰值拟合的气体超声流量计信号处理

针对从气体超声波流量计回波信号中难以确定到达时刻,而仪表又要求具有较高实时性的问题,提出一种基于回波上升段峰值拟合的气体超声流量计信号处理方法,以及拟合峰值范围的确定方法。首先根据拟合峰值范围,在回波信号的上升阶段,选取若干个峰值点,对各峰值点进行最小二乘拟合,得到特征直线,将该直线与X轴的交点作为特征点,确定回波信号的到达时刻,进而计算出超声波传播时间,得到气体流量。研制实现基于回波上升段峰值拟合的气体超声流量计,进行标定实验,以验证方法和仪表的有效性。     

仲钨酸铵在微波场中的吸波特性和升温特性研究

研究了仲钨酸铵在微波场中的吸波特性和升温行为,采用微波谐振腔法对仲钨酸铵的吸波特性进行测定。研究结果表明:仲钨酸铵在频率2.450 GHz的微波场中具有良好的吸波特性。在微波功率1 000 W、物料量12 g的条件下,仲钨酸铵在微波场中煅烧25 min后,温度达到980℃,平均升温速率为70℃/min,仲钨酸铵在微波场中升温与微波功率成正比关系。