济南污水处理厂噪声评价与治理

济南污水处理厂曝气送风系统噪声污染严重,厂界噪声超过国家标准值达30.5dB(A)。曝气送风系统噪声包括罗茨风机噪声和管道噪声、水流噪声等,经过噪声分析评价,认定管道再生噪声为主要噪声源。根据噪声分析评价,在不改变原有设备位置条件下,采取了在罗茨风机排气口、主送风道入口处加接阻抗复合式消声器,减少汇流管与主送风管道截面变化,增大它们的截面面积,将管壁较薄的不锈钢管道更换为管壁较厚的普通碳钢管等措施,有效地降低了管道再生噪声。还采取了将原罗茨风机隔声罩进气口由室外改至室内、由罩上部移至下部,提高风机房围护结构隔声能力等综合治理措施,成功地降低了罗茨风机噪声污染。治理后,厂界噪声测量值为43.5dB(A),达到国家标准要求。     

实验室通风系统风机噪声的综合治理

实验室通风系统在保证良好的室内空气质量的同时,往往会带来一定程度的噪声污染.济南市供排水监测中心综合实验室通风系统对室外环境造成了严重的噪声污染.文章对该实验室通风系统的噪声特性进行了测试与分析,结果表明:位于室外屋顶的风机为主要噪声源;阐述了针对风机噪声采用综合运用隔声罩、阻抗式消声器和隔声包扎等治理措施;提出了使用计算机模拟的方法用于噪声治理措施的选择与评价.项目竣工后,其噪声污染已控制到国家允许标准以下.     

南京市区交通噪声污染及控制对策

通过对南京市3条主要道路的部分路段环境噪声的实地监测,采用等效声级模型,对所得数据进行比较和研究,结果表明所选各个测点等效连续A声级均超过昼间70dB（A）,夜间55dB（A）.按交通噪声污染分级,其中有27%测点的道路交通昼间噪声污染属于恶化等级,73%属于坏等级.同时分析了造成交通噪声污染的主要原因,根据目前国内外噪声的各种控制方法,结合实际情况,提出了减轻噪声污染的一些措施和建议.     

CA6145i型卧式车床噪声测试与降噪处理

目的对新机型CA6145i卧式车床样机进行噪声攻关试验并进行降噪处理.方法通过精密声级计B＆K2230对噪声进行频谱分析找到噪声源，利用B＆K2148双通道便携式信号分析仪采取相应的措施降低噪声并且消除杂声.结果测试结果表明样机噪声声压级超标，并且主轴箱中伴有不规则的杂声.经降噪处理后，CA6145i型卧式车床整机噪声正常，主轴正转为82.0dB（A），主轴反转为82.5dB（A），符合国家标准GB9061-88金属切削机床通用技术条件的要求.结论CA6145i卧式车床的噪声主要来源于主轴部件、Z65/Z48齿轮及挂轮副，对其进行调整后能有效地降噪.     

螺杆压缩机振动噪声的控制

为了改善工作环境,针对某型号螺杆压缩机噪声严重超标,极大地危害工人身心健康问题,对机组振动、噪声源进行了详细分析.在其正常运转条件下进行噪声测试,最终确定出合理的噪声治理方案,即采用隔振方法降低噪声,利用消声器、空间吸声体、隔声罩等一系列措施控制螺杆压缩机的噪声.结果表明,通过上述改造,噪声值由原来的104dB降至78dB,实际结果与理论基本符合,达到了国家标准.     

锅炉房噪声控制及预评价

本文提出如何以较经济的措施控制锅炉房噪声污染问题,结合工程实例,总结了一些成功经验。重点探讨了对锅炉房主要噪声源——风机和水泵的噪声综合控制技术以及在设计中对噪声污染和治理效果的预评价计算方法。     

环境影响评价中有关冷却塔噪声问题的探讨

针对尚处于规划阶段或者初步设计阶段的民用建筑,在冷却塔方案尚未确定时,结合环境影响评价实例,从环评角度对冷却塔进行估算选型及噪声分析.根据某办公楼的实际情况,对冷却塔不同设置形式的噪声进行评价,垂直风流方向噪声较小;结合建筑物本身及周围状况对冷却塔提出合理的降噪措施,采取降噪措施后,冷却塔噪声可有效衰减20dB（A）左右.     

CXW-180-JXD28型吸油烟机振动和噪声测试分析

根据国家标准,在半自由声场的振动和噪声实验条件下,对CXW-180-JXD28型吸油烟机进行了噪声和振动测试,分析相关测试数据,找出主要振动和噪声源,并探讨了改进措施.该机型的主要振动和噪声源为离心风机和箱体,可以通过合理选型、优化风机结构、控制机械噪声等措施减少噪声与振动的产生.     

地铁线路对车内噪声的影响分析

对上海地铁9号线运行于高架段、敞开段和隧道段时的噪声分别进行了测试.从所测数据结果的分析总结中得到对地铁车内噪声影响最大的是轮轨噪声,并测得列车在通过隧道内道岔时的噪声可达95 dB(A),由此提出了车内噪声的治理措施和控制手段.     

大流量三叶罗茨风机的流量特性及噪声分析

介绍大流量三叶罗茨风机的流量特性,内泄漏、外泄露、压力比对容积效率的影响.根据回流压力的变化规律,采取异型排气口、预进气结构等措施减小回流冲击.实例说明风机的气体动力性噪声、机械噪声,比较三叶与两叶罗茨风机的进气流量脉动,分析噪声产生原因及采取的降噪措施.     

高速铁路周边建筑物环境振动现场测试与分析

对高速铁路列车引起的周边建筑物与地面环境振动响应进行现场测试,利用频谱分析方法研究高速列车引起的周边地面与建筑物环境振动特性,结合城市铁路振动控制标准对高铁环境振动影响进行分析与评价。研究结果表明：时速270 km/h的高速列车产生的环境振动频率主要集中在25~60 Hz范围内;建筑物垂直振动大于水平振动,建筑物铅垂Z振级最高可达70.62 dB,建筑物二次振动具有明显的高度放大效应,建筑物顶层铅垂Z振级约为室内地面的1.094倍;周边地面振动明显大于建筑物振动,但两者表现出相似的变化规律,周边地面分频振级最高可达92.0 dB,而建筑物分频振级最大值仅为80 dB;高速铁路环境噪声值高达92.8 dB,超过城市环境噪声重度污染标准。高速铁路产生的环境噪声污染远大于环境振动影响,须采取相应的隔声降噪措施,以重点控制高速铁路环境噪声污染。     

Review of recent progress in studies on noise emanating from rail transit bridges

In recent years, there has been rapid growth of Chinese rail transit networks. Many of these networks require elevated bridges. This results in a bridge-borne noise source, which occurs in addition to the main noise source (i.e., wheel–rail interactions). Bridge-borne noise is attracting increasing attention because of its low-frequency noise characteristics. This review paper first analyzes the space distribution, spectral characteristics, and sound pressure levels of noise radiated by all-concrete, steel–concrete composite, and all-steel bridges, mainly according to experimental studies. Second, this paper reviews existing theoretical prediction models of noise emanating from bridges: the semianalytical method, the Rayleigh integral method, the boundary element method, and statistical energy analysis. Several case studies are reviewed, and their results are discussed. Finally, according to the results of the current review, the main factors affecting bridge-borne noise are analyzed, several noise reduction measures are proposed for different types of bridges, and their effectiveness is demonstrated.

     

Vibro-acoustic performance of steel–concrete composite and prestressed concrete box girders subjected to train excitations

Owning to good mechanical properties, steel–concrete composite (SCC) and prestressed concrete (PC) box girders are the types of elevated structures used most in urban rail transit. However, their vibro-acoustic differences are yet to be explored in depth, while structure-radiated noise is becoming a main concern in noise-sensitive environments. In this work, numerical simulation is used to investigate the vibration and noise characteristics of both types of box girders induced by running trains, and the numerical procedure is verified with data measured from a PC box girder. The mechanism of vibration transmission and vibro-acoustic comparisons between SCC and PC box girders are investigated in detail, revealing that more vibration and noise arise from SCC box girders. The vibration differences between them are around 7.7 dB(A) at the bottom plate, 19.3 dB(A) at the web, and 6.7 dB(A) at the flange, while for structure-radiated noise, the difference is around 5.9 dB(A). Then, potential vibro-acoustic control strategies for SCC box girders are discussed. As the vibro-acoustic responses of two types of girders are dominated by the force transmitted to the bridge deck, track isolation is better than structural enhancement. It is shown that using a floating track slab can make the vibration and noise of an SCC box girder lower than those of a PC box girder. However, structural enhancement for the SCC box girder is extremely limited in effects. The six proposed structural enhancement measures reduce vibration by only 1.1–3.6 dB(A) and noise by up to 1.5 dB(A).

     

银川市城市环境质量状况及污染防治

运用环境科学的基本理论，分析了银川市的环境空气质量状况，城市噪声功能区的划分与噪声源的现状，银川市水环境的状况和主要排水沟的现状及固体废弃物的排放、利用情况。指出银川市环境空气质量中的主要污染物质是总悬浮颗粒物，及造成此种污染的原因；说明银川市的城市噪声源是随着城区面积的扩大，活动人群的密集，噪声幅度的增加而小幅增加的。由于水资源的需求快速增长，污染物的排放及措施的不力，使水资源面临多方压力。造成水质的主要污染因子是氨氮；水质污染类型为有机污染、无机盐类污染；银川市固体废弃物的产生量为全区第三位，工业固体废弃物综合利用率为全区首位。提出了银川市环境质量污染的防治措施。     

用数学方法对郑州城市主要空气污染物预测的机理研究

基于郑州市2003-2011年主要空气污染物的监测数据,利用灰色理论、移动平均法、指数平滑法、最小二乘法等4种数学方法,对2013—2016年郑州市空气污染物的浓度值进行预测计算．通过对4种数学方法及计算结果的分析得知,PM10仍将是未来郑州城市空气首要污染物,NO2在未来几年呈现微降趋势,SO2预测值不超出国家二级标准．     

Research on Noise Control for Ventilators with Resonance

A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz, A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB（A） in the daytime from 69.8dB（A） and to 48.4dB（A） at night from 65.8dB（A）.     

KDJ-75型晶闸管无级调压电加热机

本文作者采用一种新型触发电路,研制出晶闸管无级调压电加热机,取代以往对圆钢用煤炉加热再热压成型的旧工艺。实践证明,用晶闸管交流调压电路控制变压器输出电压,可以连续控制加热工件的温度,使产品质量显著提高,同时消除了噪声和污染,减轻了劳动强度。