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开展道路交通噪声监测是为了反映城市道路交通噪声源强,宏观评价城市平均道路交通噪声水平,并分析道路交通噪声级与车流量、路况等影响因素之间的关系。随着城市道路结构及其噪声影响日益复杂,现行方法难以满足噪声管理及防治需求,本文从监测方法和评价方法两个方面对新方法改进的要点深入分析与探讨。 相似文献
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高速铁路噪声对人群影响评价问题的探讨 总被引:3,自引:1,他引:2
实现运输高速化是我国铁路发展的重要战略目标,本文基于环境保护和卫生学分析,对高速铁路噪声影响中的人群反应,评价标准,评价方法等进行了初步探讨,以期对高速铁路噪声防治提供参考依据。 相似文献
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各种矿产资源的开发和利用是我国经济发展过程中不可缺少的重要组成部分,但是由于人类对于经济利益的过度追求,使得我国的资源问题与环境问题日益恶化,面对这样的局面,我国政府和相关工作人员,必须采取积极的措施,来进行治理和维护,这样才能够实现经济与环境效益的双增长,本文首先对我国煤炭资源的开采环境进行了总体分析,进而又对环境的影响与评价方法进行了论述。 相似文献
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通过对室内噪声的成因分析、室外声经地面传递至室内的各频段声级衰减特征以及典型固定设施噪声在房间内的噪声传递特征分析,认为对于上海市的住宅室内固定设施噪声的研究定义频段应在20~250 Hz以内,以低频噪声为主;为客观反映室内人的主观感受,参照国内外文献,结合对本市不同区域的实测室内声环境“dB(C)~dB(A)”差值对比,建议在制定上海市住宅室内固定设施噪声排放限值标准时采用"dB(C)~dB(A)的差值超过15 dB"指标预判是否存在低频噪声影响,进而再对20~250 Hz间的频谱进行限值控制。通过对低频为主的固定设备噪声特征分析,为本市住宅建筑内固定设施的噪声制定提出限值建议,为住宅室内环境治理及监管提供科学依据。 相似文献
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本文以等响处理后的车内噪声为研究对象,进行噪声声品质的主观评价研究。研究发现,人群分类处理对于揭示噪声声品质的主观感知属性起着重要的作用。对于评价者分类处理之后,两类评价者对于车内噪声的偏好性均可采用一个维度表示,并可直接采用成对比较法的直接排序法获得;一类评价者的偏好性与低沉度成正比,而另一类评价者与低沉度成反比。如果未进行人群分类处理,则不能很好地解释其主观感知属性。 相似文献
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调查收集了某城市环境噪声污染监测的历史数据,应用指数平滑法建立了预测城市环境噪声污染的数学模型,并计算了不同平滑系数时数学模型的精度,同时应用建立的数学模型对该市10 n内的噪声污染进行了预测.结果发现,噪声污染呈逐年加剧趋势,到2015年区域环境噪声和交通噪声污染分别达55.51dB(A)和70.51 dB(A).指数平滑法的应用效果与平滑系数的选取关系密切,应用时要根据指数平滑法建立的物理意义正确地分析和选取平滑系数,并对预测的精度进行分析. 相似文献
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A new implementation of the conjugate gradient method is presented that economically overcomes the problem of severe numerical noise superimposed on an otherwise smooth underlying objective function of a constrained optimization problem. This is done by the use of a novel gradient‐only line search technique, which requires only two gradient vector evaluations per search direction and no explicit function evaluations. The use of this line search technique is not restricted to the conjugate gradient method but may be applied to any line search descent method. This method, in which the gradients may be computed by central finite differences with relatively large perturbations, allows for the effective smoothing out of any numerical noise present in the objective function. This new implementation of the conjugate gradient method, referred to as the ETOPC algorithm, is tested using a large number of well‐known test problems. For initial tests with no noise introduced in the objective functions, and with high accuracy requirements set, it is found that the proposed new conjugate gradient implementation is as robust and reliable as traditional first‐order penalty function methods. With the introduction of severe relative random noise in the objective function, the results are surprisingly good, with accuracies obtained that are more than sufficient compared to that required for engineering design optimization problems with similar noise. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Wladyslaw Gardziejczyk Pawel Gierasimiuk 《International Journal of Pavement Engineering》2018,19(12):1061-1076
The texture of pavements influences the tyre/road noise. This refers especially to cement concrete pavements. This article presents the results of studies on sound level on concrete pavements in Poland, which were textured using burlap drag, broom drag and exposed aggregate methods. It was established that on exposed aggregate cement concrete, the maximum aggregate size, which is a key factor in the surface’s macrotexture, has a significant influence on tyre/road noise. It should not exceed 8 mm in the upper layer. When using aggregate size 11 mm, the maximum sound level of a passing-by car increases by approximately 2 dB. Pavements textured using the broom drag and burlap drag methods turned out to be not a beneficial solution due to the sound levels emitted by heavy vehicles moving at a speed above 80 kph. Pavement texturing using the transverse broom drag emits sound levels from heavy vehicles which are approximately 3 dB higher in comparison to values noted on SMA11. The methods of pavement texturing using diamond grinding, used in some countries, point towards the possibility of obtaining beneficial acoustic properties. 相似文献
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Jonghoon Bin Minwoo Kim Soogab Lee 《International journal for numerical methods in engineering》2008,75(8):964-991
A numerical study on impulsive noise generation produced by complex flows discharging from a muzzle is achieved and the basic structures generating impulsive noise are analyzed. Complex flow features by a muzzle flow and noise generation mechanisms by several sources of noise are discussed from numerical simulations. Two‐dimensional axisymmetric Euler equations are used for governing equations. High‐order dispersion relation preserving finite difference method and an optimized four‐level marching method are used for spatial discretization and time integration, respectively. In order to show the capability of this method to capture blast waves and to examine the basic generation mechanism of acoustic waves from a muzzle, the interaction between a shock/blast wave and a vortex ring is implemented. From the numerical simulation of the 7.62‐mm NATO rifle G3 with a DM‐41 round in the near field, complex blast waves, jet flow, various vortices and their interaction phenomena are described and noise generation mechanism due to the interaction of complex flow structures is observed. The present results demonstrate that numerical simulation using computational aeroacoustic methods provides not only a reliable way to determine the blast wave dynamics of the muzzle flow but also allows an opportunity to study the physics and detailed mechanisms of the noise generation and propagation due to the interaction of complex flow structures generated from a muzzle system. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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以中心输入式双环减速器为研究对象,综合考虑齿轮内部动态激励以及环板不平衡惯性激励,建立了减速器传动系统及结构系统的动力有限元分析模型,应用ANSYS软件对双环减速器进行固有模态及动态响应数值仿真。以振动位移作为边界条件,建立减速器箱体的声学边界元分析模型,在SYSNOISE软件中用直接边界元法计算了箱体表面声压及场点的辐射噪声。利用传动系统试验台对双环减速器进行振动加速度及辐射噪声测试,并与数值仿真结果对比分析,两者吻合良好。 相似文献
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为了获得热力膨胀阀的瞬态噪声特性,采用试验方法对不同温包充注、不同阀内结构的膨胀阀的啸叫噪声进行研究。获得了系统开机过程中热力膨胀阀啸叫噪声与温包充注、阀内结构的关系。结果表明:采用交叉充注,低蒸干压力充注,在阀内安装碟形弹簧有利于降低膨胀阀啸叫噪声。 相似文献