高效减水剂改良与发展

介绍了各种混凝土对高效减水剂的要求与改良的必要性，阐述了改性机理，指出了高效减水剂改性方法。     

Continuous monitoring of short term dissolved oxygen and algal dynamics

Dissolved oxygen (DO) in coastal bays with frequent algal blooms can undergo significant diurnal changes. Short-term DO and algal dynamics in a sub-tropical, nitrogen-limited, marine ecosystem are studied by means of a specially designed telemetry system. The high resolution data show clearly the importance of the vertical DO structure, and its relationship with environmental variables (solar radiation, water temperature, wind, tidal current) and phytoplankton dynamics. The design, instrumentation and calibration, and operational experience of the system are described. The simple and robust system has proved useful in (i) providing continuous data for full testing of water quality models, and (ii) the planning of field experiments to study algal dynamics.     

大温差粘弹性阻尼器试验研究

粘弹性阻尼材料对温度非常敏感,用一种粘弹性材料来满足大温差范围内的使用是很难的,为此提出了大温差粘弹性阻尼器,它由分别适用于高温与低温的两种粘弹性材料串联而成。通过试验发现,大温差粘弹性阻尼器可在较大的温度范围内保持较好的性能。用数理统计方法,得出大温差粘弹性阻尼器的基本参数表观剪切模量及损耗因子与高、低温粘弹性阻尼材料所占比例关系,为设计适用于不同温度范围的粘弹性阻尼器提供参考。     

萘系高效减水剂的合成

萘系高效减水剂是一种用途较广性能优越的高效减水剂。探讨了它的合成方法、反应控制因素、成品对混凝土性能的影响。     

清式天花彩画（本期中心彩色插页）说明

古代匠师广泛地选用天花装饰题材，创造了很多成功的天花装饰形式。此次介绍其中两种清式天花：沥粉贴金升降龙天花和六字真言天花。本文具体介绍此两种清式天花工艺做法和使用范围。     

大流动性高强机制砂混凝土的研究

本文论述了通过掺加矿物掺合料、高效减水剂的技术途径,利用机制砂作为混凝土的细集料,在实验室配制出了大流动性的高强机制砂混凝土。     

Sub-micrometer particulate air pollution and cardiovascular mortality in Beijing, China

Background

While the link between particulate matter and cardiovascular mortality is well established, it is not fully investigated and understood which properties of the aerosol might be responsible for the health effects, especially in polluted mega-city areas.

Objectives

Our goal was to explore the association between daily cardiovascular mortality and different particle metrics in the sub-micrometer range in Beijing, China.

Methods

We obtained daily counts of cause-specific cardiovascular deaths in the Beijing urban area for the period March 2004 to August 2005. Concurrently, continuous measurements of particle number size distributions were performed. Particle number concentrations (NC) between 0.003 μm and 0.8 μm were converted to particle mass and surface area concentrations assuming spherical particles. Semi-parametric Poisson regression models adjusting for trend, seasonality, day of the week, and meteorology were used to estimate immediate, delayed and cumulative particle effects. Additionally, effect modification by air mass origin was investigated.

Results

We observed associations between daily cardiovascular mortality and particle NC for a 2-days delay. Moreover, nearly all particle metrics showed 2-days delayed associations with ischemic heart disease mortality. The strongest association was found for particle NC in the size range 0.03-0.1 μm (7.1% increase in daily mortality with a 95%-confidence interval of 2.9%-11.5%, per an increase of 6250 particles/cm³). Results for surface and mass concentrations with a lag of two days indicated effect modification by air mass origin, whereas effects of particle NC were not modified.

Conclusions

Results show an elevated risk of cardiovascular mortality in Beijing from short-term exposure to particulate air pollution in the sub-micrometer range. Results also indicate that locally produced smaller particles and regionally transported particles may exhibit different effects in Beijing.     

四类常见边坡岩石类别识别和边界范围确定的方法

岩质边坡岩石的分类与边界范围的确定对于边坡稳定性的分析至关重要,目前人工方法效率低且受主观因素影响,所以基于Tensorflow建立了岩质边坡图像集分析的卷积神经网络模型,通过卷积操作和池化操作分别对80000张岩质边坡图像进行特征信息的提取和压缩,然后对网络模型进行训练从而实现了岩质边坡岩石的自动识别与分类;采用训练集和测试集中的岩质边坡图像对模型进行检验分析,训练集准确率达到了98%,测试集准确率达到了90%,显示了训练之后的网络模型具有良好的鲁棒性,达到了理想的训练效果。接下来以边坡不同岩石的颜色为主要区分依据,利用深度学习回归操作对岩质边坡不同种类岩石的范围进行确定,为验证算法效果,选取标准彩色岩质边坡图像进行仿真试验,边界检测效果准确。最终采用深度学习建立的网络模型,实现了岩质边坡岩石识别与边界范围划分的快速化、自动化,为后续将图像识别获取的岩质边坡信息导入团队自主研发的GeoSMA-3D软件中,作为对岩质边坡等级判定的重要参数。     

天然气转换中LPG灶具改造的试验研究

在对家用LPG灶具进行改造试验的基础上,提出改用天然气后灶具的改造方案。研究表明,燃气灶具的喷嘴进行改造后,可以满足燃用天然气的要求。     

基于分数阶Fourier变换的远程水声通信技术研究

针对水声通信中所采用的窄带信号传输距离近和抗干扰能力不足的问题,提出一种采用线性调频( LFM)作为载波信号,采用分数阶Fourier变换作为解码方式的水声通信方案.该方案采用在时域进行LFM信号的码元分割,在分数阶变换域借用脉冲位置调制(PPM)进行解码的方法进行通信,并通过Rake接收机进行路径分集接收抑制水声信道...