进气噪声产生机理分析及其降噪

在正确分析进气噪声产生机理的基础上,采用旁支型赫姆霍兹共振腔有效地使该轿车加速噪声从原来的80dB(A)降至74dB(A),效果显著。     

Should traffic-related air pollution and noise be considered when designing urban bicycle networks?

This study was motivated by an interest in capturing the factors affecting the exposure of cyclists to ambient Ultrafine Particles (UFP), Black Carbon (BC), and noise (LA_eq) across the entire bicycle network of the City of Toronto. Measurements were conducted along 270 km of unique roads, and we developed land use regression models and exposure surfaces. Median UFP, BC and noise levels recorded were 19,848 part/cm³, 1224 ng/m³, and 72.9 dB respectively. The average UFP and BC exposures along the biking routes (18,900 part/cm³ and 1130 ng/m³) were higher than the average levels measured at a fixed station located in downtown Toronto (13,300 part/cm³ and 809 ng/m³). The highest UFP and BC levels were experienced on dedicated bicycle tracks (30,000 part/cm³ and 1600 ng/m³ as median concentrations), while the highest noise levels occurred on major roads (median of 74 dB). In contrast, median levels on trails were 13,200 part/cm³, 535 ng/m³ and 70.2 dB, for UFP, BC, and noise. The exposure surfaces developed for the air pollutants and noise were intersected with the planned extensions to the bicycle network in the City of Toronto to evaluate the distributions of exposures expected across the future cycling network. We observe that the mean and median UFP, BC, and noise levels across planned facilities are equal to or significantly higher than the levels across the current network.     

Transportation planning and quiet natural areas preservation: Aircraft overflights noise assessment in a National Park

Global transportation growth causes several disproportionate impacts on the environment as, for instance, noise pollution which is related to negative effects on human health but also to quiet natural areas decline and biodiversity loss. Besides, sound is a component of ecosystems severely threatened by transportation noise disturbance which is related to negative effects on ecosystem functions. This study deals with aircraft noise impact on natural environments from a multiple innovative perspective. It complementarily combines: noise modeling, field measurements, soundscape audibility, human perception and spatial pattern tools for assessing the chronic growing outdoor noise pollution of ecosystems at landscape scale. Firstly, noticeable soundscape degradation from aircraft overflights has been found causing severe acoustic fragmentation and disruptions in the quietness of a national park in Spain (European Union). Air traffic caused sound pressure levels to increase by approximately 8 decibels from natural ambient levels. Secondly, spatial pattern tools together with noise mapping have been found to be useful in providing decision support for decisions-making through anthropogenic noise impact assessment on the natural environment. Finally, public opinion did not perceive aircraft noise-disruption as being as relevant as that quantified by technical procedures. Although 82% of visitors agree that anthropogenic noise pollution may negatively impact on conservation.     

Estimation of airport noise impacts on public health. A case study of İzmir Adnan Menderes Airport

The air transport industry is showing rapid growth in line with the call for meeting the requirements of a rising population. Noise mapping is more useful than surveys and measurements to estimate the effects of noise on public health. In this paper, noise levels for the day, evening and night time slices around İzmir Adnan Menderes Airport were calculated by use of the SoundPLAN 7.2 software according to the European Noise Directive, and the “ECAC Doc. 29-Interim” method was applied for the computation of the aircraft noise. Air traffic data of year 2012, technical information about the airport and geographical data including the layers of elevation, residential buildings, auxiliary buildings, hospitals and schools were used as the main inputs for the model developed in the study. The model was found to perform well for the areas closer to the airport. The results of the study suggested that the area at the north side of the airport, where the city center of İzmir is located, is more affected than other areas. The threshold value of 55 dB(A) was found to be exceeded in 0.3% of the land area covered by İzmir City center during the time slice “day”. The results showed that about 2% of the resident population was exposed to noise levels of 55 dB(A) or higher during day-time in İzmir. In addition, it was understood that the number of people who are potentially exposed to high noise levels and threatened by several illness such as hypertension and sleep disturbances is significant in the surrounding area of the airport. It is thought to be important for airport operators to manage the airport capacity based on the flight schedules in order to control the noise exposure level around the airport.     

基于地理信息系统的高速铁路噪声地图绘制技术

为推动噪声地图在高速铁路噪声管理中的应用,研究噪声预测模型与地理信息系统(GIS)相结合的高速铁路噪声地图绘制技术。首先,根据高速铁路噪声源分布特征和线路结构特征,优化高速铁路多等效声源预测模型和声屏障插入损失计算方法;其次,在GIS软件中搭建某高速铁路三维地理信息模型,二次开发基于该模型的铁路噪声预测技术;然后,进行离散节点的噪声计算,并通过空间插值绘制连续的噪声分布地图。研究结果表明:采用该技术绘制的我国某高速铁路噪声地图与实测结果对比误差小于1 dB (A),验证了该高速铁路噪声地图的准确性和实用性,可作为铁路噪声管理部门制定噪声控制对策的参考依据。     

Impact of simulation-based traffic noise on rent prices

This paper is part of ongoing research on incorporating environmental aspects in microscopic integrated land use/transport models. The long-term goal is to add scenario sensitivity for noise emissions in a new modeling suite. Therefore, as a first step, the influence of simulated car traffic noise on real rent prices in the study area in question is analyzed and compared to existing studies. It is shown that modeled noise values from the transportation model are able to explain significant impacts on rent prices when using a hedonic pricing regression. When using noise as a continuous variable, price discounts of 0.4% per dB(A) are found. A discount of up to 9.6% for particularly loud locations is estimated when noise is used as a categorical variable. Care should be taken when controlling for accessibilities that may correlate with noise. The results are in line with results of previous studies and confirm that environmental aspects can and should be considered in integrated models.     

铁道行业噪声作业岗位危害程度评价

在调查的２２８个典型岗位中，具有噪声危害的岗位为７１个，占调查总岗位数的３１．１％；其中Ⅰ级有害岗位占噪声有害岗位数的５０．８％Ⅱ级占２５．３％；Ⅲ级占２１．１％；Ⅳ级占２．８％。     

提速列车车厢内噪声,振动改变的探讨

对３种提速列车进行了车厢内噪声、振动测试，噪声测试结果符合车速每提高１０ｋｍ／ｈ，声级相应增加１～２ｄＢ（Ａ）的规律，噪声频谱峰值主要集中在低频段３１．５Ｈｚ及６３Ｈｚ倍频程中心频率，振动测试Ｚ向振级明显大于Ｙ向，Ｙ向大于Ｘ向，部分车厢座椅无减振作用。     

高速铁路隧道壁吸声材料降噪效果仿真分析

应用SYSNOISE软件建立列车-隧道-隧道内壁吸音板结构的二维边界元模型,研究隧道内壁吸声结构不同铺设方案下的降噪效果。根据高速铁路列车通过时隧道内壁吸声结构不同铺设面积、铺设位置等因素,分析其对列车通过时噪声的降噪效果,并综合考虑工程经济性等因素,计算4个较为典型的隧道内壁吸声结构的铺设方案。计算结果表明:在隧道内壁全部铺设吸声材料的情况下,铺设隧道吸声结构对隧道内声压级的降噪效果约为14.3dB。随着隧道内壁吸声材料铺设面积的增加,隧道内的降噪效果越好。在计算选取的4个方案中,内壁整体铺设方案降噪效果最佳,内壁部分铺设方案降噪效果最差,两者的组合方案降噪效果适中,实际工程应用中应综合各方面因素对降噪方案进行选取。     

摩托车发动机风扇噪声分析

风扇啸叫声在频谱上可看作是一条随转速升高的谐次噪声,风扇叶片数决定噪声的谐次,风扇叶片不规则分布能降低风扇啸叫声;风扇叶尖的形状影响风扇噪声,合理的叶尖形状设计能大大降低风扇啸叫噪声;不同风扇叶尖形状会使周围空气的流速变化量不同,并产生不同的湍动能,最终产生不同的噪声。