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噪声测量时点数量对8h等效声级估算误差影响的模拟研究 被引量:2
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作者 吕旌乔 曾琳 +3 位作者 李会娟 成小如 李玉秦 赵一鸣 《工业卫生与职业病》 CAS CSCD 北大核心 2008年第3期149-152,共4页
目的探讨噪声测量时点数量与工作日噪声暴露(LAeq·8h)评估准确性的关系。方法采用SH126型记录式声级计,在某纺织厂测量59个8h工作班次的噪声水平,其中挡车班次25个、机修班次34个。对每一班次的测量均按10min间隔顺序记录48个1... 目的探讨噪声测量时点数量与工作日噪声暴露(LAeq·8h)评估准确性的关系。方法采用SH126型记录式声级计,在某纺织厂测量59个8h工作班次的噪声水平,其中挡车班次25个、机修班次34个。对每一班次的测量均按10min间隔顺序记录48个10min等效连续A声级(LAeq·10min)。为模拟日常工作中根据特定时点短时噪声测量结果估算LAeq·8h的方法,应用区组随机抽样程序进行8轮抽样,分别从59组数据中抽取1、2、3、4、5、6、7、8个LAeq·10min,根据抽样结果估算8个LAeq·8h用估算LAeq·8h与真实LAeq·8h(根据全部48个LAeq·10min计算得出)之差的绝对值反映LAeq·8h估算误差,评价增加测量时点对LAeq估算误差的影响。结果挡车工、机修工噪声暴露方式明显不同,前者为典型稳态噪声暴露,而后者表现为非稳态噪声暴露。当测量时点为1时,挡车工暴露估算误差为(1.00±1.33)dB,而机修工为(8.62±11.90)dB。两类暴露LAeq·8h估算误差均随测量时点增加而下降,在测量时点数达3~4个时,下降曲线逐渐平坦。测量时点数目相等时,机修工暴露估算误差均大于挡车工。结论按单一时点的测量结果估算非稳态噪声LAeq·8h可能会导致较大误差,增加测量时点可减少估算误差。就稳态噪声暴露而言,增加测量时点去除LAeq·8h估算误差的意义较小。 展开更多
关键词 工业噪声 测量时点 8 h等效连续A声级
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Investigations of 3D Surface Roughness Characteristic's Accuracy
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作者 Maris Kumermanis Janis Rudzitis Anita Avisane 《Journal of Mechanics Engineering and Automation》 2013年第10期632-640,共9页
The existing surface roughness standards comprise only two dimensions. However, the real roughness of the surface is 3D (three-dimensional). Roughness parameters of the 3D surface are also important in analyzing the... The existing surface roughness standards comprise only two dimensions. However, the real roughness of the surface is 3D (three-dimensional). Roughness parameters of the 3D surface are also important in analyzing the mechanics of contact surfaces. Problems of mechanics of contact surfaces are related to accuracy of 3D surface roughness characteristic. One of the most important factors for 3D characteristics determination is the number of data points per x and y axes. With number of data points we understand its number in cut-off length. Number of data points have substantial influence on the accuracy of measurement results, measuring time and size of output data file (especially along the y-axis direction, where number of data points are number of parallel profiles). Number of data points must be optimal. Small number of data points lead to incorrect results and increase distribution amplitude, but too large number of data points do not enlarge range of fundamental information, but substantially increase measuring time. Therefore, we must find optimal number of data points per each surface processing method. 展开更多
关键词 Surface topography roughness assessment accuracy measurement instruction.
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