铁路噪声预测模式的监测验证与误差分析

为了验证列车通过的等效声级、等效时间及预测模式的正确性,选择了一个开阔的场所,在距离铁路外轨中心线30 m处采用两种不同的方式记录列车通过时的源强及持续时间,然后利用监测值预测60 m处的1h等效连续A声级,并与60 m处的1h等效连续A声级监测值进行对比.结果表明,列车经过身边到离开时的持续时间作为等效时间,经过身边时的最大噪声级作为源强,所得到的预测值与监测值的误差范围在-0.3～0.9 dB(A),方差为0.229,离散度较小,预测值与监测值较吻合,可用于指导设计与规划工作.同时,在分析误差产生原因的基础上,提出了提高预测准确性的建议.     

用程序计算器处理环境噪声评价数据

环境噪声评价数据的处理,目前国内有些单位还用手工计算。对于统计声级 L_(10)、L_(50)、L_(90),手工计数虽慢但甚可靠。对于等效连续 A声级Leq及反映读数波动程度的标准差σ,若用近似公式计算误差过大,而用准确公式计     

PC-1501袖珍计算机应用于长期定点环境噪声监测数据处理的程序设计

一、概述本程序为PC—1501袖珍机处理长期定点环境噪声监测的基础数据而设计,具有下列功能: (1)计算并打印全年四次、每次每个测定时间的L_(10)、L_((?)0)、L_(90)、等效声级Leq、标准偏差σ和该次全天的L_(10)、L_((?)0)、L_(90)算术均值、昼夜等效声级Ldo。     

内燃机发电机组的噪声控制

本文包括两个主要部分。第一部分介绍了内燃机发电机组噪声控制基本原理。提出降低内燃机进排气噪声雷诺数原则。第二部分介绍固定式大马力柴油机发电机组及移动式小马力汽油机发电机级的噪声控制工程实例。应用本文介绍的方法,控制内燃机发电机组的噪声,在通常节约开支的条件下,机房外墙一米的测量点,噪声可控制在60±5dB(A)的范围内。     

关于《工业企业厂界环境噪声排放标准》倍频带声压级结构传播固定设备室内噪声排放限值使用的探讨

根据现行国家噪声排放标准排放限值,文中从噪声危害角度根据噪声评价曲线,论证了结构传播固定设备室内噪声等效声级排放限值与结构传播固定设备室内倍频带声压级的等效关系。     

牡丹江市交通噪声2000年预测研究

目前,噪声预测的模型较多,本文所应用的负指数模型车流噪声预报公式的推广就是设法证明当多车通的车辆分布服从泊松时,并用一等效车道来近似代替多车道,便可将多车道车流简化为行驶在等效车道上的合成流泊松流来考虑。然后分类叠加合成车流中各辆车对测点的声强贡献,通过求声强的累积量母函数和n阶累积量表达式入手,求出声强分布的特征函败。对此特征函数作逆傅氏变换便得出声强分布的概率密度函数。在满足各态历经过程的假设下,根据声强与声压的关系及统计声级的定义求出系统计声级与等效声级。     

柴油发电机噪声与废气治理

一般国产柴油发电机工作噪声声级测定值在９０－１２０ｄＢ（Ａ）之间，安装了消声，废气处理装置后，发电过程的噪声可降至６５ｄＢ（Ａ）以下，有效地控制了废气的排放量。     

室外大型空气压缩机的噪声治理技术

某室外安装的大型空气压缩机对环境造成了严重噪声污染,离机器2m远处噪声高达114 5dB(A)。在不允许停机的情况下,充分利用现场条件,采取了为空气压缩机加隔声罩、进气口滤清器加消声百页和管道作隔声包扎等综合治理措施,相应测点噪声已降至88 7dB(A),厂界噪声降至机器安装前背景值。室外机器的噪声控制方法与室内机器有许多不同,分析了这些差异并重点介绍了所设计的隔声罩在声学、通风、耐气候性和结构等方面的设计要点。     

用单结晶体管时间触发器代替噪声监测中人工报时

进行城市环境噪声监测,需要每隔5秒钟读一个慢档 A 声级瞬时值,连读100个(或200个)数据。初搞噪声测量的人要准确地把握在每5秒末读数比较困难,一般需要三个人(报时、读数、记录各一人)。这给人手少、任务     

土壤非饱和带柴油入渗的试验研究

通过土柱模拟试验研研了0#轻质柴油(简称柴油)在不同含水率和容重的壤土及砂土中的入渗及残留特征.结果表明:(1)相同时间内,柴油在壤土中的润湿锋面下渗距离随含水率的增加不断减小,风干土中柴油穿透时间最短;柴油在砂土中的润湿锋面下渗距离随含水率的增加先增大后减小,含水率为10.0%的砂土中柴油穿透时间最短.土壤含水率对润...     

Impacts of pavement types on in-vehicle noise and human health

Noise is a major source of pollution that can affect the human physiology and living environment. According to the World Health Organization (WHO), an exposure for longer than 24 hours to noise levels above 70 dB(A) may damage human hearing sensitivity, induce adverse health effects, and cause anxiety to residents nearby roadways. Pavement type with different roughness is one of the associated sources that may contribute to in-vehicle noise. Most previous studies have focused on the impact of pavement type on the surrounding acoustic environment of roadways, and given little attention to in-vehicle noise levels. This paper explores the impacts of different pavement types on in-vehicle noise levels and the associated adverse health effects. An old concrete pavement and a pavement with a thin asphalt overlay were chosen as the test beds. The in-vehicle noise caused by the asphalt and concrete pavements were measured, as well as the drivers’ corresponding heart rates and reported riding comfort. Results show that the overall in-vehicle sound levels are higher than 70 dB(A) even at midnight. The newly overlaid asphalt pavement reduced in-vehicle noise at a driving speed of 96.5 km/hr by approximately 6 dB(A). Further, on the concrete pavement with higher roughness, driver heart rates were significantly higher than on the asphalt pavement. Drivers reported feeling more comfortable when driving on asphalt than on concrete pavement. Further tests on more drivers with different demographic characteristics, along highways with complicated configurations, and an examination of more factors contributing to in-vehicle noise are recommended, in addition to measuring additional physical symptoms of both drivers and passengers.Implications: While there have been many previous noise-related studies, few have addressed in-vehicle noise. Most studies have focused on the noise that residents have complained about, such as neighborhood traffic noise. As yet, there have been no complaints by drivers that their own in-vehicle noise is too loud. Nevertheless, it is a fact that in-vehicle noise can also result in adverse health effects if it exceeds 85 dB(A). Results of this study show that in-vehicle noise was strongly associated with pavement type and roughness; also, driver heart rate patterns presented statistically significant differences on different types of pavement with different roughness.     

Traffic noise exposure of high-rise residential buildings in urban area

Noise pollution is a major factor of environmental complaints in many cities, which has significant impacts on human health. As a dominating source of environmental noise, the impact of road traffic noise is increasing. Residents living in high-rise buildings along the main road are severely affected by traffic noise. In order to assess the noise level of urban area along the main road in Guangzhou, three buildings were selected to conduct traffic noise measurements, and the questionnaire about traffic noise impact on human being was completed. Through the questionnaire, around 70% of participants consider the traffic noise has negative effect, and about 60% of participants consider the noise has moderate or much higher impact on physical comfort. Around 65% of participants consider the noise had moderately or much higher impact on their psychological comfort. By analyzing the measured data, all of the measured noise levels in three buildings exceed the recommended limit of 55 dB (A) in the daytime and 45 dB (A) in the night for residence, and the exceeded value can be up to 16 dB (A). By comparing the fitting curve of noise level transfer function on each floor relative to the reference floor, the quadratic polynomial was selected to plot the transfer function rather than cubic polynomial.

     

Implementation of a top-down noise control strategy for a liquefied natural gas peak-shaving facility

There have been many previous noise-related studies on liquefied natural gas (LNG) facilities in the United States; however, noise control of these facilities using a top-down approach has not been explored in detail. Most studies have demonstrated noise compliance to applicable standards by focusing on a combination of treatments and specifications, with less consideration on control technology feasibility, ranking, and cost-effectiveness. The Federal Energy Regulatory Commission (FERC) prohibits natural gas facilities from emitting day-night noise levels in excess of 55 dB(A) (equivalent to 24-hr continuous level of 49 dB(A)) at nearby receivers. A case study was conducted to evaluate a top-down approach to reduce noise at a typical LNG peak-shaving facility under normal operating conditions, accounting for technical feasibility, control effectiveness, and cost implications. A modeling approach (International Organization for Standardization standard ISO 9613-2) was used to predict and evaluate the facility’s noise reduction potential. The study found that the strategy could achieve feasible and environmentally effective reductions up to 11 dB(A) at 500 m from the facility by first identifying source groups with highest-emitting sources and then targeting major noise source contributors per group. This approach is cost-effective because the FERC noise goals can still be achieved by avoiding unnecessary control costs associated with lower-ranked sources. The study identified the following four source groups as the highest noise emitters: (1) liquefaction and instrument air, (2) boil-off gas (BOG) compression, (3) glycol water system (air coolers), and (4) pretreatment. Of all the treatments evaluated, installation of enhanced silencers for gas turbine (GT) package—as well as construction of an acoustical building for the BOG compressors and drivers—resulted in the greatest noise reduction at nearby receivers. The study notes that incremental treatment costs presented in this paper are approximate estimates that may vary depending on factors such as facility size and region.

Implications: This study assessed potential noise reductions associated with implementing a top–down noise control strategy on a typical LNG peak-shaving facility. The study determined the top–down noise control strategy could achieve feasible and environmentally effective reductions up to 11 decibels at receivers within 500 m from the facility’s center. As LNG suppliers need to support potential supply disruptions, some regions of the US, including New England and Gulf Coast with projected increase in LNG exports and growing needs from power sector, may find information in this study useful with regard to evaluating and prioritizing noise reduction potential of their LNG peak-shaving facilities.     

Environmental noise in hospitals: a systematic review

Environmental noise has been growing in recent years, causing numerous health problems. Highly sensitive environments such as hospitals deserve special attention, since noise can aggravate patients’ health issues and impair the performance of healthcare professionals. This work consists of a systematic review of scientific articles describing environmental noise measurements taken in hospitals between the years 2015 and 2020. The researchers started with a consultation of three databases, namely, Scopus, Web of Science, and ScienceDirect. The results indicate that for the most part, these studies are published in journals in the fields of medicine, engineering, environmental sciences, acoustics, and nursing and that most of their authors work in the fields of architecture, engineering, medicine, and nursing. These studies, which are concentrated in Europe, the Americas, and Asia, use as reference values sound levels recommended by the World Health Organization. L_eq measured in hospital environments showed daytime values ranging from 37 to 88.6 dB (A) and nighttime values of 38.7 to 68.8 dB (A). L_eq values for outdoor noise were 74.3 and 56.6 dB (A) for daytime and nighttime, respectively. The measurements were taken mainly inside hospitals, prioritizing more sensitive departments such as intensive care units. There is a potential for growth in work carried out in this area, but research should also include discussions about guidelines for improvement measures aimed at reducing noise in hospitals.

Graphical abstract

     

城市天然气加气站噪声影响分析及噪声控制技术简

城市天然气加气站位于城市道路和居民区周边。由于加气站地理位置特殊，声源复杂，与周边道路对环境的影响叠加，还要考虑通风散热等问题，噪声治理难度大。目前，国内关于城市天然气加气站的噪声控制研究的报道较少。本研究以合肥市长江西路天然气加气站为例，根据城市天然气加气站加气工艺噪声源及邻近交通噪声对周围环境进行叠加影响预测，根据预测结果和通风散热等工艺要求设计冷却塔安装进风、出风消声器和隔声罩，压缩机安装局部通风隔声罩及压缩机房东墙内安装隔声墙及通风隔声窗等措施。经检验，研究结果好于《工业企业厂界噪声排放标准（GB12348-2008）》中的2类标准的夜间50 dB（A）的标准。该研究设计技术工艺、参数先进合理，费用低且实际简单，为国内天然气加气站噪声预测及治理提供较好的示范作用。     

道路交通噪声预测模式预测结果的比较

为了分析实际环境影响评价中常用的各种公路交通噪声预测模型预测结果之间存在的差异,并验证各预测方式与实测值之间的相符性,通过对选取的高速公路和市政快速公路采用各种预测模型计算比较,并用实际监测值对各模型预测结果进行验证,结果发现,不同的预测方式会造成预测结果之间昼间4～9 dB、夜间5～10 dB的差异,采用2006版规范计算车速和单车噪声源强,距离衰减考虑车流量大小的预测方式得到的预测结果与实测值最为接近。     

Use of Noise Attenuation Modeling in Managing Missile Motor Detonation Activities

Abstract

The Sound Intensity Prediction System (SIPS) and Blast Operation Overpressure Model (BOOM) are semiempirical sound models that are employed by the Utah Test and Training Range (UTTR) to predict whether noise levels from the detonation of large missile motors will exceed regulatory thresholds. Field validation of SIPS confirmed that the model was effective in limiting the number of detonations of large missile motors that could potentially result in a regulatory noise exceedance. Although the SIPS accurately predicted the impact of weather on detonation noise propagation, regulators have required that the more conservative BOOM model be employed in conjunction with SIPS in evaluating peak noise levels in populated areas. By simultaneously considering the output of both models, in 2001, UTTR detonated 104 missile motors having net explosive weights (NEW) that ranged between 14,960 and 38,938 lb without a recorded public noise complaint. Based on the encouraging results, the U.S. Department of Defense is considering expanding the application of these noise models to support the detonation of missile motors having a NEW of 81,000 lb. Recent modeling results suggest that, under appropriate weather conditions, missile motors containing up to 96,000 lb NEW can be detonated at the UTTR without exceeding the regulatory noise limit of 134 decibels (dB).     

室内箱式变压器结构声污染及对策

通过对置于住宅楼底层室内箱式变压器引起的结构声污染进行调查实测，在对箱式变压器结构声传播进行声学分析基础上，提出了切实可行的防治对策，经实际工程应用验证，效果较好。对机房正上方住房主卧内降噪量为5.0dB，室内夜间噪声降为30.2dB，各层住户夜间烦恼度普遍从非常烦恼或烦恼降为有点烦恼和不大烦恼。这从噪声污染控制的角度证明了变配电房置于住宅楼等噪声敏感建筑物室内底层甚至更高楼层在技术上是可行性的。同时也为杭州市正在试点推广的箱式变压器置于噪声敏感建筑物底层提供了实践依据。     

Effect of Plantings on Radiation of Highway Noise

The body of information presented in this paper is directed to those individuals concerned with the location of highways relative to either existing or planned residential communities. The paper treats in depth the expected attenuation of automobile and particularly diesel tractor-trailer generated hoise by the interposition of extensive and dense planting of trees and shrubs between the highway and the community. The results of research, by the author and others cited in the paper, gives clear indication that a belt of dense man-made growth of tall trees and underbrush can give as much as 5 to 8 dB truck/car noise reduction per 100 ft of planting depth. Natural growth of deep forests were measured to give from 3 to 5 dB attenuation per 100 ft of planting depth. Planting depth of at least 100 ft is required to give reliable results, with tree heights of 40-50 ft desirable and densities of 50-70 ft visibility needed for good effect.

The paper provides considerable experimental verification by an analysis of the current literature. The types of noise sources in cars and trucks are briefly treated as are community reactions to noise from such sources. The dBA is used as the accepted measure for characterizing truck and automobile noise. Both spherical and cylindrical radiation of sound are discussed for low density and high density traffic, respectively.

The paper concludes with an example of attenuation of a typical truck noise by spherical and cylindrical radiation for low- and high-density traffic and a 200-ft deep planting of dense, mature forest. It is concluded that a mature belt of either coniferous or deciduous forest with underbrush can produce barely acceptable noise levels in the community which is separated by such a noise barrier from a heavily traveled highway.