纳米氧化铝弥散强化铜涂层硬度的研究

采用大气等离子喷涂制备了氧化铝弥散强化铜涂层,对涂层2小时600℃真空热处理前后的硬度进行了对比,并对涂层显微组织进行了分析。结果表明,热处理前后涂层的硬度基本没有发生变化,宏观硬度平均值在83HR15Y～84HR15Y之间,显微硬度平均值在216HV0.05～219HV0.05之间。涂层中纳米氧化铝颗粒均匀分布,尺寸在40～200nm之间。纳米弥散强化颗粒对位错的阻碍作用是涂层硬度保持不变的主要原因,而影响弥散强化效果的主要因素是颗粒尺寸和弥散分布程度。     

基于高速摄像技术的旋流器空气柱特征研究

利用高速摄像技术研究了不同锥角和进口流量下旋流器内空气柱的结构特征。结果表明,旋流器内空气柱的形状、弯扭程度因旋流器锥角和进口流量不同而不同,不能单纯用柱状、麻花状、正弦曲线状等来描述。因此,为减少空气柱对旋流器分离效率的影响,旋流器应采用合适的锥角及与之相匹配的最佳进口流量。     

中国煤炭消耗及其对环境影响的评估分析

分别从整体、年代、省际、部门的视角分析了1953～2006年间我国煤炭的消耗状况。50多年来,我国煤炭的消耗量除1960年代出现减少趋势外,其余年份均呈现不同程度不同趋势的增加。我国煤炭的消耗大省多集中于北方,且主要集中在电力、热力生产供应业、石油加工炼焦及核燃料加工业、黑色金属冶炼及压延加工业等工业部门。采用相关文献中的参数计算出1953～2006年间我国由于燃煤所产生的CO2、SO2、NO2与灰尘的累计量分别为8212807.24,51330.05,18821.02万t与376420.33万t。     

Optimizing the energy and exergy of building integrated photovoltaic thermal (BIPVT) systems under cold climatic conditions

Building integrated photovoltaic thermal (BIPVT) system has the potential to become a major source of renewable energy in the urban environment. In this paper, the system has been used as the roof top of a building to generate higher electrical energy per unit area and to produce necessary thermal energy required for space heating. One-dimensional transient model has been developed using basic heat transfer equations. On the basis of this model, an analysis has been carried in order to select an appropriate BIPVT system suitable for the cold climatic conditions of India. The PV performances, net energy gain and exergy of the building are determined. The results show that for a constant mass flow rate of air the system connected in series gives a better performance whereas for a constant velocity of air flow the system connected in parallel gives a better performance. The BIPVT system, fitted on the rooftop in an effective area of 65 m², is capable of annually producing the net electrical and thermal exergies of 16,209 kW h and 1531 kW h, respectively, at an overall thermal efficiency of 53.7%.     

Impact of climate change on commercial sector air conditioning energy consumption in subtropical Hong Kong

Past and future trend of electricity use for air conditioning in the entire commercial sector in subtropical climates using 1979–2008 measured meteorological data as well as predictions for 2009–2100 from a general circulation model (MIROC3.2-H) was investigated. Air conditioning consumption showed an increasing trend over the past 30 years from 1979 to 2008. Principal component analysis (PCA) of measured and predicted monthly mean dry-bulb temperature, wet-bulb temperature and global solar radiation was conducted to determine a new climatic index Z for 1979–2008 and future 92 years (2009–2100) based on two emissions scenarios B1 and A1B (low and medium forcing). Through regression analysis, electricity use in air conditioning for the 92-year period was estimated. For low forcing, average consumption in 2009–2038, 2039–2068 and 2069–2100 would be, respectively, 5.7%, 12.8% and 18.4% more than the 1979–2008 average, with a mean 12.5% increase for the entire 92-year period. Medium forcing showed a similar increasing trend, but 1–4% more. Standard deviations of the monthly air conditioning consumption were found to be smaller suggesting possible reduction in seasonal variations in future years.     

Virtual models of indoor-air-quality sensors

A data-driven approach for modeling indoor-air-quality (IAQ) sensors used in heating, ventilation, and air conditioning (HVAC) systems is presented. The IAQ sensors considered in the paper measure three basic parameters, temperature, CO₂, and relative humidity. Three models predicting values of IAQ parameters are built with various data mining algorithms. Four data mining algorithms have been tested on the HVAC data set collected at an office-type facility. The computational results produced by models built with different data mining algorithms are discussed. The neural network (NN) with multi-layer perceptron (MLP) algorithms produced the best results for all three IAQ sensors among all algorithms tested. The models built with data mining algorithms can serve as virtual IAQ sensors in buildings and be used for on-line monitoring and calibration of the IAQ sensors. The approach presented in this paper can be applied to HVAC systems in buildings beyond the type considered in this paper.     

采空区自燃带宽度理论分析

治理煤矿自燃对矿井生产至关重要。在分析煤矿采空区支承压力的分布和空气流动状态的基础上,推导了采空区中部空气流速分布规律,用数值方法确定出特定条件下自燃带宽度。经分析可知：燃烧区域靠近工作面,燃烧宽度随距工作面距离变化小;工作面越长,燃烧区域越靠近工作面,燃烧宽度基本不变;采空区支承压力变化率越小,燃烧区域距工作面距离随宽度的增加而增大。     

福岛核事故期间浙江地区空气中放射性水平应急监测

福岛核事故发生后,浙江省辐射环境监测站在浙江省境内开展了空气中放射性水平的应急监测.本文介绍此次应急监测的内容,对测量结果进行了分析,为类似辐射应急监测提供了几点建议.     

光干涉法高精度材料线膨胀系数测量

中国计量科学研究院研制的高精度材料线膨胀系数测量装置,满足温度范围为5～40 ℃、被测件长度在20～1 000 mm之间的线膨胀系数测量。采用激光干涉法测量被测件长度变化量,用高精度温度传感器测量温度值。设计了热平衡式干涉镜,利用空气折射率修正和零位误差补偿技术,保证在5～40 ℃变温范围内激光干涉仪的测量精度。以500 mm标准量块作为测量对象,线膨胀系数测量结果与德国物理技术研究院(PTB)测量结果的相对偏差为0.2%。材料线膨胀系数测量不确定度达到3×10^-8K^-1。