城市“达标仍烦恼”开放区域声环境质量评价指标研究

大部分城市区域居住环境为2类声功能区，昼间声级在60 d B以内，尽管能被2类区中大部分人接受，但还有部分人在该类声环境中有烦恼的感觉，这被称为“达标仍烦恼”现象。为了找出该现象背后的声学原理，即人群的烦恼度与等效A声级以及其他声学特征的内在联系，从人群主观感知角度出发，针对人口、交通密集型城市开放空间“达标仍烦恼”区域声环境质量评价开展研究，拓展现有单一A声级评价指标，确定“达标仍烦恼”区域的声级区间以及影响该区域声环境质量评价的“烦恼指标”。基于对上海市整体开放空间声环境主观满意度评价结果中的烦恼度区间划分，结合前期研究得到的5个独立声环境客观特征参量：等效连续A声级L_A、噪声中值与环境本底值的差值L₅₀-L₉₀、A声级与C声级的差值L_C-L_A、波动度F以及尖锐度S等，得到城市“达标仍烦恼”区域L_A的区间，即L_A∈[53.6,60]，并构建上海市2类声环境功能区“达标仍烦恼”区域“特征参量-主观满意度”样本集。进而，采用Pears...     

基于降维-回归的车内声品质时变烦躁度评价

用心理声学参量表征声品质评价指标,可直观描述人对噪声信号的主观感觉。相比于听审团评分,它具有简单快速、效率高的优点,在此基础上将多个客观参量降维到低维空间,用少数具有代表性的参量定量表征主观感受,有利于声品质评价的标准化。通过采集轿车车内噪声信号,以等间隔不同车速状态和怠速状态下的噪声样本作为研究对象,考虑汽车车内噪声特性的时变效应,分别计算出噪声样本的心理声学客观参数时变算术平均值。提出以“时变烦躁度”作为主观评价指标,以语义细分法结合数字等级评分法作为主观评价方法进行主观评价试验。用因子分析对6种客观参量进行降维,结合显著相关性分析确定出响度(Z)、粗糙度、AI指数3个客观参量,并用多元回归建立声品质烦躁度评价预测数学模型。预测结果显示：回归预测三参量模型的相对误差率在5%以下,比六参量模型相对误差率低,预测效果比较理想,说明这3个参量可以有效表征主观烦躁度,同时证明噪声声品质的时变烦躁度评价预测模型是有效的。     

汽车发动机启动声品质评价与分析

以驾驶员耳处采集的乘用车发动机启动时声样本为对象,分析了其时频域分布,计算了声样本的基本物理参数、心理声学参数和烦恼度指标。运用成对比较法进行了声样本主观评价实验,得出各声样本主观偏好性得分。通过主、客观参数的相关分析和回归分析表明:烦恼度模型能正确预测声样本的主观偏好性,双耳响度和粗糙度是影响主观偏好性评价的主要客观参量,用对数变换后的拟合模型能更好的描述主观评价结果与客观参量之间的关系。     

响度感知特征研究进展

响度是反映人耳对声音强弱感知的最基本参量,它是分析计算很多其它心理声学参量的基础。响度特征的研究不仅在噪声评价、心理学及声品质方面有重要的应用,还广泛应用于语音信号处理等方面。在此从等响曲线、双耳异响条件下的响度感知特征以及纯音和复音时变信号响度感知特征等三个方面介绍了近年来的研究结果。     

国内森林旅游者声景喜好特征分析

为了考察中国游客对森林声景的喜好特征，对森林景观规划设计与旅游管理提供指导，通过设计与发放Likert量表与语义细分量表，结合聚类分析与因子分析，就中国游客对于森林环境中单一声源与整体声环境的偏好特征进行分类统计。研究发现，在森林环境中，自然声的整体喜好度最高，交通声最低，但针对具体的声源有不同的评价，不能一概而论。此外，选取20组语义评价指标对森林声环境进行7级尺度评价，发现影响森林声环境喜好的4个主要因子为休闲娱乐、空间特性、声音的音质与动态以及环境知觉。所提取的主导因子对全部指标参量的覆盖率为61.054%，结果较为理想。因此在森林景观规划设计中，需突出游客评价值较高的声源，同时重点关注对森林声环境主观感知评价起主导作用的因子，进而实现降维和简化问题的目的。     

高速动车组噪声声品质实验及其客观评价方法

在高速动车组减振降噪设计中,声品质已成为舒适性评价的重要指标之一。Zwicker提出了对噪声进行主观评价的客观量化方法,本文以其理论为基础,深入分析4种噪声客观评价参量（响度、尖锐度、粗糙度、抖动度）的计算方法,并且以高速铁路动车组车内噪声为例进行相关参量的试验测试。得出车内典型位置不同运行速度时各心理声学参量的现状和分布规律,其结论为高速铁路动车组车内声品质研究提供依据。     

高速动车组噪声测试及其声品质客观参量分析

在高速动车组减振降噪设计中,声品质已成为舒适性评价的重要指标之一。以Zwicker提出的对噪声进行主观评价的客观量化方法为基础,通过响度、尖锐度、粗糙度和抖动强度4种噪声客观评价参量计算方法对某高速铁路动车组车内噪声试验测试数据进行分析,得到车内典型位置不同运行速度时各心理声学参量的现状和分布规律,可为高速铁路动车组车内声品质研究提供参考依据。     

重型商用车噪声测试及声品质客观评价分析

在重型商用车减振降噪设计中,声品质已成为舒适性评价的重要指标之一。以Zwicker提出的对噪声进行主观评价的客观量化方法为基础,通过响度、尖锐度、粗糙度、抖动强度、音调度和语言清晰度6种噪声客观评价参量计算方法对某国产重型商用车加速工况车内噪声试验测试数据进行分析,得到车内副驾驶员各项心理声学参量的变化规律,可为商用车车内声品质研究提供参考依据,并对建立加速工况下商用车声音品质烦躁度的客观量化模型提供参数基础。     

基于多特征融合的乐器声品质评价方法研究

在乐器声品质研究中,以往研究主要是从乐器的结构以及物理特性出发,忽略了乐音本身的重要性以及客观评价测量的不易实现性.为此,提出了一种基于多特征融合的乐器声品质评价方法.通过主观评价法获取乐器琵琶的声品质评价结果,建立具有主观评价的乐音信号库作为实验对象;提取乐音信号的相关系数(CC)、常数Q变换(CQT)和梅尔频率倒谱系数(MFCC)作为单一特征输入,以及多特征融合输入;并构建基于BP神经网络的乐器声品质评价模型.实验结果表明,该方法可以很好地应用于乐器声品质评价.     

声环境评价的双耳听觉适应方法

声环境评价涉及到许多的参量。有声学量也有听觉量。听觉量一般需通过听觉实验来测量，这在实际中常常是很难实现的。本文介绍的“声环境评价的双耳听觉适应方法”，通过模拟人的左右两耳的拾音及听觉系统的双耳信号处理过程，按人的主观判断标准，用物理测量的方法估计听觉量的大小。本方法尚处于发展之中。     

法向振动对Burridge-Knopoff模型Stick-Slip运动影响数值研究#br#

Burridge-Knopoff 模型是研究地震和其他机械系统动力学行为的实用模型。考虑到摩擦力的影响,Burridge-Knopoff 模型运动呈现出动力学非线性,Stick-Slip 运动是这种模型的典型运动特征。滑块法向振动对这种模型运动行为的影响规律尚未被有效研究,为此建立一种考虑了滑块法向振动影响的Burridge-Knopoff 模型。Stribeck 模型被用来刻画依赖于滑块与传送带之间相对速度的摩擦力。采用数值方法分析系统的典型运动规律,研究法向振动的频率和相位对系统运动模式的影响规律,考虑法向振动的Burridge-Knopoff 模型存在混沌和分岔现象得到证实。     

Ultrasonic Velocity Studies of Drug Parvon-spas in Mixed Alcohol–Water Solvent Systems at 25°C

Ultrasonic velocities and densities of the drug Parvon-spas in binary mixtures of water with methanol (MeOH), ethanol (EtOH), and propan-1-ol (1-PrOH) have been measured over the complete solvent composition range at 10 mol% intervals at 25°C. Various acoustic parameters such as the acoustic impedance (Z), adiabatic compressibility (β), intermolecular free length (L_f), relative association (R.A.), molar volume (V_m), and molar sound velocity (R_m) have been calculated. In addition, excess functions, i.e., excess adiabatic compressibility (β^E), excess intermolecular free length (L_f^E), excess molar volume (V^E), excess ultrasonic velocity (U^E), and excess acoustic impedance (Z^E) for these three solvent mixtures in the absence and presence of the drug have been calculated. A different behavior of these parameters in these alcohol systems has been discussed in terms of the length of the alcohol molecule, the molecular volume, as well as inter/intramolecular interactions of these molecules.     

Transferring biological sequence analysis tools to break-point detection for on-line monitoring: A control chart based on the local score

The Lindley process defined for the queuing file domain is equivalent to the cumulative sum (CUSUM) process used for break-point detection in process control. The maximum of the Lindley process, called local score, is used to highlight atypical regions in biological sequences, and its distribution has been established by different manners. I propose here to use the local score and also a partial maximum of the Lindley process over the immediate past to create control charts. Stopping time corresponds to the first time where the statistic achieves a statistical significance less than a given threshold α in ]0,1[, the instantaneous first error rate. The local score p value is computed using existing theoretical results. I establish here the exact distribution of the partial maximum of the Lindley process. Performance of the control charts is evaluated by Monte Carlo estimation of the average run lengths for an in-control process (ARL₀) and for an out-of-control process (ARL₁). I also use the standard deviation of the run length (SdRL) and the extra quadratic loss (EQL). Comparison with the usual and recent control charts present in the literature shows that the local score control chart outperforms the others with a much larger ARL₀ and ARL₁ smaller or of the same order. Many interesting openings exist for the local score chart: not only Gaussian model but also any of them, Markovian dependance of the data, both location and dispersion monitoring at the same time can be considered.     

Experimental study on the packing densification of mixtures of spherical and cylindrical particles subjected to 3D vibrations

To identify the dense packing of cylinder–sphere binary mixtures (spheres as filling objects), the densification process of such binary mixtures subjected to three-dimensional (3D) mechanical vibrations was experimentally studied. Various influential factors including vibration parameters (such as vibration time t, vibration amplitude A, frequency ω, vibration acceleration Γ) as well as particle size ratio r (small sphere vs. large cylinder), composition of the binary mixtures X_L (volume fraction of cylinders), and container size D (container diameter) on the packing density ρ were systematically investigated. The results show that the optimal vibration parameters for different binary cylinder–sphere mixtures are different. The smaller the size ratio, the less vibration acceleration is needed to form a stable dense packing. For each binary mixture, high packing density can be obtained when the volume fraction of large cylindrical particles is dominant. Meanwhile, increasing the container size can decrease the container wall effect and get higher packing density. The proposed analytical model has been proved to be valid in predicting the packing densification of current cylinder–sphere binary mixtures.     

Analytic approximation of the interval of Bayes actions derived from a class of loss functions

Due to a lack of time or limited information, a precise determination of the loss function, and the computation of the associated Bayes action is not always possible. For these reasons, statisticians use mathematically tractable losses instead of subjective ones. We study the legitimacy of such lossesl ₀ with specific properties, by first constructing a class aroundl ₀ which contains all plausible subjective losses, and then computing the setA ^π of Bayes actions associated with this class. We derive an analytic approximation toA ^π. We apply these results whenl _o is the quadratic, LIXEX and entropy loss. Finally, we investigate robustness characteristics using the analytic expression ofA ^π.     

钛合金蠕变损伤的非线性Lamb波检测

金属材料在高温高压服役过程中会发生蠕变损伤,检测和评价金属材料的早期蠕变损伤具有重要工程意义。针对Ti60钛合金蠕变损伤采用非线性Lamb波进行检测,分别选择Lamb波S_1-S_2模式对和A_4-S_8模式对开展钛合金蠕变损伤试样的实验测量,并采用归一化非线性参数来表征钛合金的蠕变损伤状态。研究结果表,明两种模式对的归一化非线性参数随着材料蠕变损伤程度的加剧均表现出"上升-下降"的变化趋势,且A_4-S_8模式对归一化非线性参数变化率比S_1-S_2模式对更大,说明该模式对对Ti60钛合金蠕变损伤更为敏感。     

Professional culture and risk perception: Coping with danger on board small fishing boats and offshore service vessels

This paper discusses the relationships between subjective risk perception and individuals’ adaptation to high-risk working conditions. It is based on a study carried out among personnel on offshore service vessels in the North Sea and Norwegian fishermen. Risk perception, fatality rates and the discrepancy between subjective risk perception and formal risk levels are compared. The results of these comparisons are discussed by using the concept of culture, and indicate that a correlation between formal risk estimation and subjective perception does not necessarily exist. In fact, subjective risk perception may be seen as a reflection of interactional conventions developed among employees dealing with their working conditions, more than as a reflection of the formal estimated risk level.     

基于声学客观参量的车内烦恼度评价

研究车内噪声客观参量与主观感受之间的影响关系。根据车辆安装5种排气系统后在8种不同档位不同转速行驶工况下的车内烦恼度主观评价分值以及11项声学客观参量,采用多元统计的聚类分析根据相似程度将客观参量分类,结合因子分析和相关分析分别提取出了在中低转速和中高转速下最能表征烦恼度的客观参量,将主观烦恼度与客观声学参量相关联,最后采用多元线性回归建立了基于声学客观参量的中低转速和中高转速下车内烦恼度预测模型,相关分析显示,其预测结果与主观评价值之间有较高的相关性。因此,基于声学客观参量的车内烦恼度评价是可行的。     

Effects of creep properties of materials on unified creep constraint parameter Ac for cracked pipes

Extensive finite element analyses of cracked pipes with different crack sizes and orientations have been conducted to investigate effects of creep properties of materials on the unified creep constraint parameter A_c. The results show that the constraint parameter A_c is independent on Norton’s coefficient A, and it is only affected by the creep exponent n of materials. For a given crack size, with increasing n, A_c decreases and constraint level increases. The A_c of lower constraint cracks is more sensitive to n. The unified correlation equations between A_c and n have been obtained for cracked pipes with a wide range of crack sizes and constraint levels. They may be used to estimate the constraint parameter A_c at different positions along the crack fronts in cracked pipes made of materials with different n values. The two-parameter C*-A_c approach for assessing creep life of cracked pipes has also been discussed.     

A general equation of state for dense fluids

A general equation of state, originally proposed for compressed solids by Parsafar and Mason, has been successfully applied to dense fluids. The equation was tested with experimental data for 13 fluids, including polar, nonpolar, saturated and unsaturated hydrocarbons, strongly hydrogen bonded, and quantum fluids. This equation works well for densities larger than the Boyle density ρ_B [1/ρ_B=T _B d B ₂(T _B)/T], where B₂(T_B) is the second virial coefficient at the Boyle temperature, at whichB ₂=0 and for a wide temperature range, specifically from the triple point to the highest temperature for which the experimental measurements have been reported. The equation is used to predict some important known regularities for dense fluids, like the common bulk modulus and the common compression points, and the Tait-Murnaghan equation. Regarding the common points, the equation of state predicts that such common points are only a low-temperature characteristic of dense fluids as verifed experimentally. It is also found that the temperature dependence of the parameters of the equation of state differs from those given for the compressed solids. Specifically they are given byA ₁ (T)=a ₁+b₁T+c₁T²-d₁ T ln (T).