城市道路交通噪声烦恼度社会调查

本文以烦恼度为主观反应指标,采用三种5级程度衡量尺度,对西安市内三条主要干道和两类典型交叉口附近区域内的道路交通噪声进行了烦恼度问卷调查。此次调查针对人口统计学因素(性别、年龄、文化程度、身体健康状况)上的个体差异与等级描述词不同的程度尺度可能对道路交通噪声烦恼度调查结果的影响,以及特定路况条件下的噪声烦恼度与不同机动车辆的行驶噪声烦恼度展开了研究。通过对调查数据的分析处理,发现并初步总结出:与选取不同的烦恼度尺度相比,人口统计学因素对调查结果的影响更加显著;人口统计学因素与特定路况条件下的噪声烦恼度及不同机动车辆的行驶噪声烦恼度无明显相关;但不同机动车辆的行驶噪声烦恼度不同,实际研究中需对摩托车噪声加以重视并区别对待。     

典型城市地铁站台噪声满意度*

地铁是城市轨道交通重要组成部分,地铁站台噪声对乘客身心健康有重要影响。以合肥轨道交通一号线为例,具体选择地下侧式、地下双岛式和地下岛式3个典型空间类型的地铁站台为研究对象,通过噪声测量和问卷调查相结合的方法,针对地铁在不同运营时段的乘客站台噪声满意度与噪声声元素舒适度进行评价,探讨性别、声元素舒适度以及站台噪声对乘客噪声满意度的影响。结果表明：对地铁站台噪声满意度评价,乘客性别差异不显著;在乘车高峰期时段,地铁站台广播提示声、地铁工作人员吹哨声、列车进站声和列车出站声是影响乘客站台噪声满意度主观评价的主要噪声声元素;乘客噪声满意度主观评价与站台噪声值呈强负相关,噪声值越高,满意度越低;乘客噪声满意度为可接受时的地铁站台噪声阈值,在乘车高峰期时段为74 dB(A),非高峰期时段为67 dB(A)。该文工作可为城市地铁站台噪声满意度评价及其空间结构设计提供科学参考。     

滨海公共空间声环境感知评价及影响因素*

滨海公共空间是滨海城市人居环境的重要组成部分,其声环境质量是影响公共空间环境体验的关键因素。本研究以青岛沿海岸线四类滨海公共空间（步道类、广场类、公园类、沙滩类）的声环境为对象,通过问卷调查和实地测量探索滨海公共空间声环境的特征、感知评价及其影响因素。结果表明：（1）滨海公共空间当前环境噪声水平基本不超过国家标准限值55dB(A) ,各类空间声环境客观特征显著不同：公园噪声水平最低,自然声源丰富;广场噪声水平最高,各种城市噪声较多;步道噪声水平较低,但受到交通噪声的影响;沙滩噪声水平较高,但以中低频的海浪声为主,比较稳定。（2）各类滨海公共空间的声源感知以自然声为主,但是广场的自然声源感知较少。此外,声环境的愉悦感评价普遍较高,但在事件感、吵闹度和总体满意度评价上具有显著差异：沙滩声环境总体评价最好,其次是公园,广场和步道的声环境则亟待改善。（3）交通噪声和最大声级Lmax对声环境的负面影响最为显著,此外受访者年龄也是影响滨海公共空间声环境感知评价的关键因素。研究结论可以为滨海公共空间声环境的优化设计提供理论依据。     

汉传佛教寺院声环境安静度评价及其影响因素研究*

本文通过在4个汉传佛教寺院的调查和分析,对寺院声环境安静度评价及其主客观影响因素进行研究。首先实地测量各寺院的总体声环境,并针对寺院声环境及安静度评价的各个因素,在寺院内发放调查问卷。研究结果表明4个寺院全天平均声级差别不大,70%的人对寺院声环境总体评价为安静或比较安静。客观因素中实测A声级和不同寺院环境同声安静度评价显著相关,当寺院的声级超过61dBA时大部分人会有造成吵闹的感觉,且声级和安静度评价的相关性大幅提高。被调查者特征中年龄、职业、教育程度、信仰因素同其对寺院内声安静度评价显著相关,性别和来寺院的次数对声安静度评价没有显著相关。     

利用卷积网络的高速列车主观声品质预测*

随着高速列车在中国的高速发展,乘客对舒适性的要求也在提高,因此高速列车内声学舒适性是一个需要研究和解决的问题。首先,本文基于声学人工头设备,获取了高速列车行驶在350 km/h速度下不同车厢不同区域的双耳噪声样本,并对其分别开展了主观声学评价和基于响度、尖锐度、粗糙度和抖动度等参数的客观声品质分析。结果表明,350 km/h速度下高速列车车内噪声能量集中在3000 Hz以内,风挡区域是舒适性评价较差的位置,而响度是影响主观评价最大的因素。其次,利用卷积神经网络算法将主观评价结果与高速列车噪声样本相关联,建立了车内噪声主观声品质预测模型,并与基于BP神经网络的预测模型进行了对比。结果表明,基于卷积神经网络的主观声品质预测模型具有更高的预测精度,可以用于指导高速列车车内声学舒适性的优化设计。     

车内噪声品质主客观评价探究式教学实验

基于探究式教学思想,针对"汽车噪声分析与控制技术及应用"课程,面向车辆工程专业学生设计了汽车车内噪声品质主客观评价探究式教学实验,且开发了车内噪声心理声学评价指标分析计算的辅助教学软件,可在实际汽车内先通过丹麦B&K公司3560型噪声采集系统进行实验测试,然后在实验室内回放进行车内声品质的主客观分析评价. 实验过程中学生在了解车内噪声心理声学主、客观评价指标的基础上,主动参与车内噪声测量和主、客观评价两部分实践环节,促进对理论课相关知识的理解.     

语音特性及声场因素对老年人警报语音可懂度和主观感受的影响*

警报语音广播是紧急情况时提高建筑物内疏散效率的有效手段。通过实验室研究的方法,研究了语音特性及声场因素对老年群体警报语音可懂度和主观感受的影响。主观感受选取了听音容易程度和感知紧迫性两个维度。研究结果表明,老年人警报语音可懂度和听音容易程度评价主要受语速、信噪比和混响时间的影响,且呈现一致的变化趋势,即随着语速和混响时间降低以及信噪比的增加,老年人可懂度和听音容易程度得分均升高,而声压级(最低设置为60dB)、有无警铃和噪声类型没有显著影响。感知紧迫性随语速和声压级的增加而显著增加,信噪比、混响时间及有无警铃声对感知紧迫性并无显著影响。采用人声播报的警报语音其可懂度和感知紧迫性显著高于合成声。比较老年人和年轻人群体的结果发现,在语速、声压级和噪声类型对主观评价的影响上有显著差异。为建立老年人理想且安全的声环境,应采用人声播报并适当降低语速以保证可懂度,同时混响及信噪比条件两方面的改善都是必要的。     

采用生理响度感知机制的车内噪声声品质预测

现有车内噪声声品质预测的响度计算中没有考虑真实人耳生理解剖结构的传声特性,因此提出了一种基于生理响度感知模型的车内噪声声品质预估方法。首先,采集两款轿车的车内噪声样本,并通过主观评价试验得到车内噪声的主观评价烦恼度。之后,整合中耳集总参数模型与耳蜗传输线模型,构建生理响度模型。然后,以生理响度模型的响度计算值为主要参数,结合尖锐度、粗糙度与车内噪声的主观评价值,通过TabNet模型构建了车辆声品质预测模型。最终,对比分析了所构建声品质模型与基于现有标准响度模型所构建的声品质模型的预测效果。结果表明,采用生理响度模型的声品质预测平均误差百分比仅有4.73%,优于采用Moore响度(6.13%)与Zwicker响度(6.94%)的声品质预测结果。此外,所构建的TabNet声品质预测模型的平均误差百分比也低于基于BP神经网络模型的平均误差百分比(7.60%)。采用生理响度模型的TabNet声品质预测能够提高车内噪声声品质客观评价的准确率。     

某汽车传动系扭振测试、诊断与数据处理分析

本文针对某轻型卡车由于传动系扭振导致加速过程中驾驶室内出现异常振动与轰鸣噪声现象进行研究。首先,为弄清车内振动噪声产生机理,对整车的扭振和车内振动噪声进行了实车道路试验;其次,对整车试验异常数据进行后处理,通过低通滤波和设置电压波动缓冲区的方法对其进行去噪和再生成,消除了加速工况下转速曲线失速和异常峰值的现象;最后,通过分析转速、振动和噪声数据得出：样车加速过程中发动机2阶激励频率达到整车传动系的固有频率时,引起了传动系扭转共振,连同传动轴的不平衡转动自振,通过悬置、中间支撑和后桥板簧传入到车内,引起驾驶室异常振动和轰鸣噪声。     

试析PBL教学法对《大学物理》学习效果的影响

为探索PBL教学法在大学物理学习中的应用效果,抽取安阳师范学院2013级电气工程及其自动化专业两个班级作为试验组、对照组,两班年龄、成绩差异无统计学意义,运用PBL教学法和传统教学法完成教学任务后,进行理论、实践成绩分析并进行调查问卷。结果显示PBL教学组学生理论、实践成绩均高于对照班,差异具有显著性(P0.05)。调查问卷显示此教学法对学生综合素质的提高具有促进作用。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.