共查询到18条相似文献,搜索用时 750 毫秒
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对乙烯装置裂解炉安全阀噪声源强理论计算方法进行介绍,主要为API STD 521、噪声与振动控制工程手册及工程噪声控制理论和实践的理论计算公式。通过选取API STD 521方法进行计算,同时考虑实际工作情况的管道距离衰减、自由空间距离削减、指向性削减及A声级修正等方法,进行操作人员位于裂解炉工作平台区域噪声限值模拟计算分析与研究,最终满足操作人员工作区域噪声限值要求。 相似文献
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调查了测量20多家大,中,小氮肥厂的噪声状况,分析了氮肥厂机械设备噪声的声级分布范围和噪声源特性,探讨了氮肥厂所特有的几种噪声源的现状,对如何所肥厂噪声提出了基本对策。 相似文献
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1 前言 目前,我国水泥企业普遍存在多种噪声源,其中粉碎机(破碎机和磨机)、风机、空压机、包装机、输送机等设备以及窑头点火装置的噪声,大部分均超过国家允许的85dB(A)噪声级(见表1)。噪声严重影响人的神经和听力,甚至可引发心血管和消化系统的疾病。因此,控制和解决水泥厂的噪声污染已成为当前劳动保护和环境保护刻不容缓的任务。笔者在这一方面进行了探索和研究,现简介如下。 相似文献
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(一)概述 随着高速、大型、大功率设备和运输工具的使用,噪声已成为矿山环境的主要污染源。据统计,目前井下工龄10年以上的凿岩工有20%听力暂时衰退,80%职业性耳聋。 据测定和调查,矿山井下噪声存在有声源多、声级高、频谱宽、连续噪声多、衰减慢等特点,各种设备噪声级都在95~110分贝(A),有的超过150分贝(A),噪声频谱呈高,中频,噪声级超过国家颁布的标准。图为矿山主要机械设备的声级范围。 相似文献
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简要介绍了水泥厂的主要噪音源、噪声级;对噪声治理的基本原理和技术线路进行了逐一分析介绍;最后就水泥厂主要噪声的形成原因及其针对性的治理措施进行了一一列举。 相似文献
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An investigation was carried out on the features of potential electrochemical potential noise of stressed AISI321 stainless steel in solution 0.5 mol/L Na2SO4 + 5 × 10−3 mol/L H2SO4 under constant-strain-rate-testing (CSRT) conditions. The results showed that the strained steel exhibited a white noise feature at low frequencies and the amplitude of potential fluctuation depended on elongation of the steel. Power spectral density (PSD) of the noise increased with increasing strain level. The noise level in the elastic region of the steel was relatively low, which increased with elongation. After the steel yielded, the electrochemical noise level became higher but it increased less significantly with increasing strain. In the fracture region, the potential noise reached the maximum level. In addition to the dependence of electrochemical noise on strain level, it was also found that the electrochemical noise level increased with increasing strain rate. To interpret the generation mechanism of electrochemical noise, a simple model was proposed based on an assumption that strain results in breakdown and repairing of the passive film on the steel. With this model, the dependence of electrochemical potential noise and its power spectral density on strain level and strain rate can be successfully explained. 相似文献
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城市交通干线和居民区的矛盾日愈明显,市民对交通噪声的投诉也日愈增加.文章作者通过分析大量的实测数据,探讨城市交通干线边的高层(34层,约100米)建筑物,其交通噪声的分布规律.统计分析发现,不同楼层的噪声差别不大,其中2~11层(约30米以下)逐步小幅度升高,最大值出现在11层(约30米),再往上逐步小幅度降低;不同朝向的噪声差别较大,朝路一侧明显高于背路一侧. 相似文献
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《Carbon》2013
Transport properties of single-walled carbon nanotube (CNT) structures with Pd contacts were studied using noise spectroscopy. The high values of the mobility and low noise level are characteristic of high-quality CNT material. The detailed analysis of the transport and noise properties of the CNT structure with back gate topography allows us to study the transport determined by Schottky barriers and by pure CNT channel conductivity and to establish their separate contribution to the total conductivity of the structure. It was demonstrated that at small gate overdrive the main source of flicker noise is related to the Schottky barriers of the CNT–FETs. With increasing gate voltage, the magnitude of flicker noise decreases and at a certain gate voltage it is only determined by the transport properties of carbon nanotubes with a noise level lower by one order of magnitude. In contrast to previous studies where flicker noise determined the excess noise of CNT-based structures, we registered generation–recombination noise components in our structures and studied their behavior in a wide temperature range. This allowed us to investigate the origin of traps capturing the carriers, which considerably affects the noise and transport properties of CNT structures. 相似文献
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研究横向细沟槽对轮胎胎面花纹噪声的影响.结果表明,无论加刻什么类型的横向细沟槽,声压级都大幅升高;速度对声压级的影响程度大于负荷;在3种类型的横向细沟槽中,S形直沟槽噪声较小,且正、反转时声压级差异小;15°斜沟槽声压级较0°与15°交替排列沟槽略高,但0°与15°交替排列沟槽的正转和反转声压级差异较大. 相似文献