舰船噪声包络谱分析

用希尔伯特变换求舰船噪声信号的包络谱，通过对实测舰船信号的分析，讨论了舰船信号包络谱和功率谱之间的关系。     

A methodology for classification by priority for action: Selecting road stretches for network noise action plans

Road traffic noise is an element of outstanding importance within the overall context of environmental impact. This problem must be technically addressed from an efficient viewpoint, and solutions or alternatives should be considered by means of appropriate and consolidated procedures.Up to now, there is no regulated guideline for establishing well-founded priorities when dealing with the diverse road stretches included in the corresponding Action Plans against noise under the Environmental Noise Directive (2002/49/EC). To this end, the present study proposes a methodology to sort, by priority, road stretches identified by their noise problems and therefore requiring appropriate action. The methodology is based on the so-called “road stretch priority index” (henceforth referred to as RSPI). This index involves a number of variables (called “road stretch priority variables”) that are weighted according to their influence on the road traffic noise problem. Thus, the RSPI makes it possible to prioritize different stretches of the Action Plan. To illustrate the application of the proposed methodology, this paper also describes a real case entailing a difficult choice, applying the proposed methodology to a review of the Action Plan against Noise 2008–2012 in the province of Almería, for the road network of the regional government of Andalusia, Spain.     

交通噪声预测遮挡衰减取值研究

分析了交通噪声预测模式中房屋遮挡衰减量估算中存在的问题。针对不同的公路项目提出了实测和类比两种解决方案。研究结果表明,通过实测法和类比法,可以有效解决房屋遮挡衰减量估算中存在的误差。     

On the dependence of acoustic performance on pavement characteristics

Acoustic-based mix design is still far from achieving a clear and accepted rationale. The three main dominions (generation, absorption, propagation) which affect pavement acoustic performance involve a number of acoustic parameters. Their relationship with pavement properties is scarcely or insufficiently known. In more detail, the parameters that define the acoustic coupling between the two phases that comprise a porous material are: porosity, resistivity, tortuosity, and viscous and thermal factors. Consequently, the spectrum of a pavement absorption coefficient depends, in particular, on tortuosity, whose relationship with HMA (hot mix asphalt) bulk properties is still an issue.Given that, the study described in this paper aimed at: (i) assessing the effect of the tortuosity on the absorption coefficient of a pavement layer; (ii) assessing the dependence of tortuosity on mix design parameters and/or mix properties; (iii) deriving a straightforward algorithm to estimate the effect of tortuosity-related properties on the absorption coefficient.Based on the above issues, an experimental plan was designed and carried out in order to study these relationships and set out a tentative theoretical and practical framework. The relationships between acoustic and traditional bulk properties of pavement mixtures were analysed. Acoustic models and hydraulic analogies were considered and, based on them, relationships were formalised and submitted to experimental validations. A simple relationship to derive tortuosity from nominal maximum aggregate size and thickness was derived. This relationship was used to derive the frequency of the first peak of the absorption spectrum, based on HMA properties. Nominal maximum aggregate size and lift thickness emerged as key factors in patterning peak frequency.Future research will address a number of issues among which the following can be listed: synergetic assessment of the influence of HMA properties on the absorption coefficient over the entire spectrum, synergetic consideration of generation and absorption factors. Practical benefits and outcomes are expected for both practitioners and researchers.     

城市地铁车站钻孔桩旋挖施工噪音对周边环境的影响分析

以北京地铁6号线一期工程南锣鼓巷站为背景,研究了夜间进行钻孔灌注桩旋挖施工对周边房屋所产生的噪音影响。通过对实际检测结果的对比分析得出了夜间进行旋挖施工对周边环境的噪音影响很小,可以正常组织施工,为类似工程提供借鉴经验。     

统计能量法预测铁路声屏障的降噪效果

用统计能量分析（简称SEA）来预测铁路声屏障的降噪效果,并针对某一有声屏障的铁路段进行了SEA模。模型包含列车车体与声屏障之间的声空间以及声屏障2个子结构。计算结果与常用的经验计算方法的预测结果相近。     

高速铁道车辆噪声机理解析

随着金质奖箅辆速度的增加,噪声也随之而加大,噪声传递到车内,会使乘客的乘车舒适度降低,传递到车外,会使铁路沿线两侧的居民深受其害,因此,如何降低车辆噪声具有较高的现实意义。通过对日本新干线高速铁路车辆进行噪声机理解析和现车试验,提出了降低噪声的主要方法。     

基于EMD和ARMA模型桥梁振动信号降噪的处理方法

在桥梁振动信号的采集和传输过程中,针对外界环境的影响可能会在信号中形成局部强噪声干扰,从而造成分析结果的失真以及由于桥梁振动信号通常具有较宽的频谱成分,致使传统的滤波降噪方法存在很大的局限性等问题,基于经验模态分解(EMD)和自回归滑动平均(ARMA)模型提出了一种信号降噪方法。首先,利用EMD把有强噪声干扰的信号分解成不同时间尺度的本征模函数(IMF)和残余项;然后,分别对每个IMF无干扰区段建立ARMA模型,利用各个模型对有干扰区段进行滤波,用滤波后的数据代替原来的数据,对于残余项,拟合为多项式;最后,将所有的IMF及拟合后的残余项叠加,即得到降噪后的信号。通过对实测南京长江大桥有对讲机干扰的应变信号进行分析,结果表明了该方法的可行性及有效性。     

铁路车辆运行噪声的源强参数

通过分析比较，确定了以单节车辆运行的声暴露级LSEO作为铁路列车运行噪声预测的基本源强参量，并给出了确定LSE0的计算方法和测量方法。在现场试验的基础上，确定了客、货列车在基本运行和线路条件下的源强参数值，可用于铁路列车运行噪声的预测。     

SET OPERATOR-BASED METHOD OF DENOISING MEDICAL VOLUME DATA

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