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测量水中微气泡尺度分布的图像处理 被引量:7
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作者 孙春生 张晓晖 韩宏伟 《光电工程》 CAS CSCD 北大核心 2012年第1期7-11,共5页
针对水中微气泡尺度分布参数在线测量的需求,提出了一种测量水中微气泡尺度分布的图像处理与分析方法。以在实验室显微照相拍摄的水中微气泡图像为研究对象,阐述了该方法所采用的图像增强、图像分割、图像形态学处理和图像颗粒测量的具... 针对水中微气泡尺度分布参数在线测量的需求,提出了一种测量水中微气泡尺度分布的图像处理与分析方法。以在实验室显微照相拍摄的水中微气泡图像为研究对象,阐述了该方法所采用的图像增强、图像分割、图像形态学处理和图像颗粒测量的具体手段,给出了其中单幅微气泡图像的尺度分布测量结果。实验与分析结果表明,该方法能有效地获取水中微气泡的尺度分布,并能分离粘连气泡,可应用于水中气泡群参数的在线检测。 展开更多
关键词 图像处理 微气泡 尺度分布 颗粒测量
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A Study of Hygiene in Swedish Schools and Pre-Schools-Sources of Air Pollution 被引量:1
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作者 Thomas Alsmo Catharina Alsmo 《Journal of Environmental Protection》 2013年第12期1349-1359,共11页
Poor indoor air quality is a large problem in Swedish schools, since the health of occupants may be affected. The building itself is often in focus and other building-related problems may be neglected. The hypothesis ... Poor indoor air quality is a large problem in Swedish schools, since the health of occupants may be affected. The building itself is often in focus and other building-related problems may be neglected. The hypothesis of this study is that factors other than the building itself have decisive influence on indoor environment. An assessment of these nonspecific building-related reasons for bad indoor environment has been made in the present work using surveys combined with particle measurements and comfort measurements (air humidity and air temperature). People are experiencing poor indoor air quality, the air is too dry and the temperature is uneven and uncomfortable indoors in the winter. It is important to highlight the problem of indoor environments with high particulate emissions especially in the range from 5.0 microns and larger since they are conveyers of allergens and bacteria, combined with dry air. An interesting observation regarding the ventilation system is that mechanical systems are tending to generate drier indoor air than the natural ventilation system. Results show that it is possible to decrease emissions through eliminating activity-related sources of airborne contaminants and better the comfort indoors with relatively simple measures. 展开更多
关键词 HYGIENE HYGIENE and Health Air Quality Sick Building Syndrome (SBS) particle Implication particle measurements INDOOR ENVIRONMENT INDOOR Humidity INDOOR Temperature particle Size particle Amount Physical ENVIRONMENT
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A Comparison of Relative Humidity between Two Swedish Buildings with Different Ventilation Solutions 被引量:1
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作者 Thomas Alsmo Catharina Alsmo 《Journal of Environmental Protection》 2016年第6期855-873,共19页
This project is based on measurements of the parameter relative humidity, RH (%), in two buildings: one with natural ventilation and one with mechanical ventilation. Both buildings are located in central Sweden, which... This project is based on measurements of the parameter relative humidity, RH (%), in two buildings: one with natural ventilation and one with mechanical ventilation. Both buildings are located in central Sweden, which constitutes a representative climate zone with respect to Swedish conditions. An important factor for the indoor environment, which affects human health and well-being, is the level of the relative humidity, RH (%). Research studies show that the healthiest level should be in the range of 40% - 60%. Surveys have revealed that about 70% of the employees at Swedish offices, schools and kindergartens experience that the air is too dry during the winter season. Previous studies show that the level of relative humidity in the indoor environment influences the prevalence of respiratory infections and allergies. The purpose of this study is to investigate how the relative humidity differ between the two buildings, and if this may be a cause of the health problems that users are affected by. During many years, users have complained about the environment in the building with mechanical ventilation and that they suffer from health problems. The method used in the study is air measurements of the two parameters, relative humidity and air temperature in the two buildings using data loggers. The indoor environment is affected by the outdoor climate and therefore instruments are placed outdoors to record seasonal variations. The measurements were carried out during the period October 2014 to September 2015 to include all of Sweden’s four seasons with completely different climatic conditions. The results of this study show that the relative humidity in the mechanically ventilated building is consistently significantly lower than in the building with natural ventilation whatever the time of year and temperature indoors. This study shows that mechanical ventilation in buildings affects the indoor environment negatively with respect to human health during most time of the year and this fact must be taken into consi 展开更多
关键词 HYGIENE Hygiene and Health Air Quality Sick Building Syndrome (SBS) particle Implication particle measurements Indoor Environment Indoor Humidity Indoor Temperature particle Size particle Amount Physical Environment
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轴流泵非稳定工况下叶轮进口流场试验研究 被引量:19
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作者 杨华 孙丹丹 +1 位作者 汤方平 张雪峰 《排灌机械工程学报》 EI 2011年第5期406-410,共5页
在小流量工况下,由于轴流泵不稳定工况区(马鞍区)的存在,使其稳定运行的范围大大缩小.详细测量了轴流泵能量性能参数,获得了'双马鞍'形的扬程-流量曲线,采用PIV技术对0.73Qd,0.55Qd0,.43Qd及0.33Qd流量工况下的叶轮进口轴面流... 在小流量工况下,由于轴流泵不稳定工况区(马鞍区)的存在,使其稳定运行的范围大大缩小.详细测量了轴流泵能量性能参数,获得了'双马鞍'形的扬程-流量曲线,采用PIV技术对0.73Qd,0.55Qd0,.43Qd及0.33Qd流量工况下的叶轮进口轴面流场进行了二维流速测量.结果表明:小流量工况下,在叶轮进口靠近壁面处存在明显回流,回流区域随流量的减小而增大,同时叶轮进口轴面内湍流强度也随着流量减小而增大;相同工况下,轴向流速的湍流强度低于径向流速的湍流强度,靠近叶轮外壳处的湍流强度大于靠近轮毂处的湍流强度;通过流道壁面上的丝线示踪,显示了随着流量的减小,叶轮进口外壁处的流体由轴向流动向周向流动的演化过程.研究结果表明小流量工况下,轴流泵叶轮进口流场不稳定导致水泵效率偏低,为进一步提高水泵性能提供了参考. 展开更多
关键词 轴流泵 非稳定工况 PIV测量 流场 小流量
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PIVS方法测雾滴粒径的影响因素及其实验验证 被引量:4
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作者 王喜世 廖光煊 秦俊 《热科学与技术》 CAS CSCD 2004年第3期229-233,共5页
在分析讨论 PIVS ( particle image velocimetry and sizing)方法测量喷雾场粒子粒径的影响因素的基础上 ,通过建立基于标准粒子的粒子场实验模拟装置 ,对 PIVS系统粒径测量结果进行了验证。结果表明 :现有系统只适用于对大粒子 (如平... 在分析讨论 PIVS ( particle image velocimetry and sizing)方法测量喷雾场粒子粒径的影响因素的基础上 ,通过建立基于标准粒子的粒子场实验模拟装置 ,对 PIVS系统粒径测量结果进行了验证。结果表明 :现有系统只适用于对大粒子 (如平均粒径大于 1 1 5μm)粒径的精确测量 ,要实现对小粒子 (如粒径小于 5 0μm)粒径的测量 ,仍需改善其成像系统的性能。 展开更多
关键词 两相流 粒径测量 PIV/PIVS 流体力学 喷雾燃烧 景深 衍射 空间分辨率
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基于质点振速测量的薄板瞬态力重建方法
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作者 胡龙 张永斌 +1 位作者 张小正 毕传兴 《机械工程学报》 EI CAS CSCD 北大核心 2022年第1期108-115,共8页
基于质点振速测量重建了作用于薄板表面的瞬态力。首先根据薄板的运动方程推导了板表面上力谱与振动速度谱之间的脉冲响应函数,再联立板表面上振动速度谱和全息面上质点振速谱之间的脉冲响应函数,在波数域-时域中构建了力谱和质点振速... 基于质点振速测量重建了作用于薄板表面的瞬态力。首先根据薄板的运动方程推导了板表面上力谱与振动速度谱之间的脉冲响应函数,再联立板表面上振动速度谱和全息面上质点振速谱之间的脉冲响应函数,在波数域-时域中构建了力谱和质点振速谱之间的传递关系;在此基础上,以全息面上测量的质点振速作为输入,重建出了每一个波数点处的力谱,并通过对力谱作空间Fourier逆变换得到了板表面上的瞬态力。数值仿真和实验结果验证了基于质点振速测量重建瞬态力方法的可行性和有效性,它不仅能定位出激振力的位置,而且可以重建出力的时间历程。同时,与现有的基于声压测量的重建方法相比,本文方法可以获得相似的重建精度,但重建过程更简单。该方法提供了一种实时、非接触式的测量方式来获取薄板所受的瞬态力,且建立的力和声辐射间的直接联系有助于进一步探索噪声产生的机理。 展开更多
关键词 力重建 瞬态力 薄板 质点振速测量
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沙漠沙的筛分粒径与粒径计粒径的比较实验 被引量:5
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作者 吴世亮 倪晋仁 李振山 《泥沙研究》 CSCD 北大核心 2002年第1期60-65,共6页
筛分法与粒径计法是两种重要的颗粒分析方法。本文通过较为系统的实验发现采用这两种方法所得到的实验结果之间存在较大的偏差。采用粒径计法测得的样品粒径较之用筛分法所得的结果明显偏大 ,说明用这两种原理不同的颗分方法所测出的粒... 筛分法与粒径计法是两种重要的颗粒分析方法。本文通过较为系统的实验发现采用这两种方法所得到的实验结果之间存在较大的偏差。采用粒径计法测得的样品粒径较之用筛分法所得的结果明显偏大 ,说明用这两种原理不同的颗分方法所测出的粒径数据不能不加换算地直接采用。由于目前有关筛分粒径与粒径计粒径转换关系的研究结果并不一致 ,所以文中比较了几家代表性研究成果之间的差异 ,重点讨论了采用不同沉降速度公式进行计算时所得粒径计粒径之间的差异 ,探讨了各家结果不同的原因 。 展开更多
关键词 沙漠 颗粒分析 筛分粒径 粒径计粒径 筛分法 粒径计法
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