BP神经网络在扬声器异常音检测中的应用

提出一种采用人工神经网络判断扬声器是否存在异常音的方法。首先简单介绍了获取扬声器异常音曲线的方法和人工神经网络中的BP模型及其训练方法,并比较了基本BP算法和共轭梯度法两种训练方法的差异。再将所获得的异常音曲线作为人工神经网络的输入向量,将听音员的听测结果作为目标向量,并使用共轭梯度法进行网络的训练。最后通过已训练好的人工神经网络判断扬声器是否存在异常音。实验结果表明,该方法可替代传统的人工设置门限的方法,并可大幅降低扬声器异常音检测的虚警率。     

一种扬声器异常音的时域特征检测方法

扬声器的异常音故障常见于生产过程中,通常可由有经验的听音员凭人耳听音检测出来。与人耳听测异常音的机理类似,一种在时域检测异常音的方法被提出。通过对声响应信号进行经验模态分解得到本征模态函数,再根据本征模态函数与激励信号的瞬时频率差对各模态去混淆处理,可得到包含异常振动信息的模态函数,据此可判断是否存在异常音。算法验证分为仿真和实验两部分。仿真验证中分析了模拟的合格扬声器与故障扬声器的声响应,结果表明算法对于摩擦和碰触导致的异常音是灵敏的。实验验证中检测了20只扬声器,测量得到的故障频率与用高阶谐波失真法得到的结果一致。且对于不同异常音故障,可在经验模态函数的局部特征中观察到不同的时域特征。     

VMD-Hilbert变换在扬声器异常声检测中的应用

针对基于时频分析的扬声器异常声检测方法中短时傅里叶变换、小波包变换存在的不足,提出了一种基于变分模态分解-希尔伯特(Variational Mode Decomposition and Hilbert,VMD-Hilbert)变换的扬声器异常声检测方法。首先通过仿真信号分析,研究了VMD-Hilbert变换的时频特性,并与其他三种时频分析进行了对比,结果表明VMD-Hilbert变换具有更好的自适应性、能量聚焦性与时频分辨率。然后,对实测扬声器声响应信号进行VMD-Hilbert变换,求得被测扬声器单元的时频矩阵与标准时频矩阵之间的特征距离,并与其它三种时频分析下的特征距离进行对比。实验结果表明,VMD-Hilbert变换下的类间特征距离的离散度较大,便于更好地设定阈值,从而验证了VMD-Hilbert变换能更好地表征异常声的时频特征,以及其在处理非线性、非平稳的扬声器声响应信号时的优越性。     

基于短时傅里叶变换的异常音检测方法

提出一种基于短时傅里叶变换的扬声器异常音检测方法,该方法首先对由扫频信号激励的扬声器声响应信号进行短时傅里叶变换,然后根据扬声器异常音信号的特点将所获得的时频图分割为若干区域,并提取各个区域内的时频图所对应的矩阵,最后通过计算被测扬声器声响应信号所对应区域内的矩阵与黄金样品所对应的矩阵之间的距离来判断该扬声器是否存在异常音。还简要介绍了基于该方法实现的扬声器异常音在线检测仪,实验室及企业生产线初步检验结果表明,该方法简单有效,可用于部分种类扬声器的异常音在线检测。     

从掩蔽效应和鸡尾酒效应探究听觉

掩蔽效应和鸡尾酒效应是人耳听觉效应里两个非常重要的部分。很多人都认为,掩蔽效应和鸡尾酒效应是两个完全不相同的概念,甚至有人曾经明确地指出过,掩蔽效应是关于听觉生理上的一种现象,鸡尾酒效应是关于人的听觉心理上的一种表现;也有一部分人将鸡尾酒效应认为是人耳掩蔽效应的一种。对于各种不同的解释,下面希望能通过一些更深人和清晰的了解去探究一下两者的关系。同时,通过一些非常独特的视角,来重新审视它们。     

车内噪声听觉时域掩蔽主动控制LMS算法

在传统噪声主动控制LMS算法基础上,考虑人耳听觉感知的后掩蔽效应,推导出Post-masking LMS算法。以汽车车内噪声主动降噪为例,分别采用LMS与Post-masking LMS算法,在Matlab环境中对实测的不同车速下车内噪声信号进行有源噪声控制仿真试验,结果表明Post-masking LMS算法能在传统LMS算法的基础上进一步降低车内噪声响度水平,具有更好的降噪效果和主观听觉感受。     

视频监控中的快速异常检测与分析

异常检测是视频监控中目标识别与跟踪的基础。本文提出了一种快速异常检测与分析算法,主要进行了有条件背景替换的检测,并采用分块的方法进行视频分析。同时提出了视频异常检测算法的评价准则,构造了检测标准视频序列。最后给出了实验结果。     

电—声类比在扬声器系统设计中的应用

《音响技术》杂志的各位编辑：您们好！我是一个音响技术的爱好者和贵刊的忠实读者,虽然现在远在美国留学,也不忘请亲朋好友从国内寄来每一期《音响技术》。目前,我在读声学方向的ＰｈＤ,我对电声学和音响尤为感兴趣,我觉得利用电声类比的等效电路来分析频响是个很...     

应用变分模态分解和随机森林特征选择算法的扬声器异常声分类

为了提高扬声器异常声分类的精度,提出了基于变分模态分解(variational mode decomposition, VMD)和随机森林特征选择算法的扬声器异常声分类方法。首先利用VMD分解采集到的扬声器声响应信号,之后对得到的一系列模态分量提取时域和频域特征;然后利用随机森林特征计算提取特征的重要性,通过递归特征消除算法提取出相关性较强的特征构造出最优特征子集;最后将最优特征子集输入至随机森林分类器中,实现扬声器异常声的分类识别。试验结果表明,该方法可以筛选出规模较小且识别度较高的低维特征数据集,同时具有更好的平均识别准确率,平均识别准确率为98.61%。     

环绕声拾音技术在影视同期录音中的应用

本文通过对环绕声拾音技术的分析,结合影视同期录音的特点和要求,探讨适合影视同期录音使用的环绕声拾音方法,并通过实践检验,分析使用中的优缺点。     

道路交通事故受害者生活质量的损失计量方法

生活质量的损失是道路交通事故经济损失的重要部分，文章分析了国际上道路交通事故受害者生活质量损失的研究，提出了适合我国国情的生活质量损失综合评价指标体系，构造了生活质量经济损失的计量模型，并对北京市１９９３年道路交通事故受害者的生活质量的损失进行了实际测算。     

道路交通事故受害者生活质量的损失计量方法

生活质量的损失是道路交通事故经济损失的重要部分 ,文章分析了国际上道路交通事故受害者生活质量损失的研究 ,提出了适合我国国情的生活质量损失综合评价指标体系 ,构造了生活质量经济损失的计量模型 ,并对北京市 1 993年道路交通事故受害者的生活质量的损失进行了实际测算     

质量屋中顾客需求向技术特征映射的一种方法

在利用质量功能配置(QualityFunctionDeployment,QFD)进行产品规划决策时,根据顾客需求选取技术特征,是实现产品规划中顾客域到技术特征域转换进而进行产品规划的关键。建立了资源约束下最大化顾客满意程度和最大化技术特征集表现度的整数规划模型,实现了顾客需求域到技术特征域的映射,从而确定出质量屋决策中需重点考虑的技术特征项,并给出了实例。     

An application of cost-effective fuzzy inventory controller to counteract demand fluctuation caused by bullwhip effect

This paper develops a fuzzy inventory model to counteract the demand fluctuation in supply demand networks, which combines fuzzy logic controller with (s,?S) policy based on economic order quantity (EOQ) model. Following a literature review and a discussion of counteractions to the bullwhip effect and the obstruction of general counteraction in supply demand networks, a multi-echelon fuzzy inventory model in supply demand networks is proposed. A simulation model with one- and two-echelon supply demand network is built and tested for (s, S) policy based on the classical EOQ model and the proposed fuzzy inventory model. Based on the simulation, results of the relevance performance are presented and discussed, which show that the proposed multi-echelon fuzzy inventory model provides not only a cost-effective management of inventory (e.g. lower inventory levels and cost) in market uncertainty, but also another effective alternative for counteracting demand fluctuation. In particular, the proposed multi-echelon fuzzy inventory model shows benefit in counteracting demand fluctuation in multi-echelon supply demand networks. Finally, some conclusions and suggestions for further research works are presented.     

Interdisciplinary safety analysis of complex socio-technological systems based on the functional resonance accident model: An application to railway trafficsupervision

This paper presents an application of functional resonance accident models (FRAM) for the safety analysis of complex socio-technological systems, i.e. systems which include not only technological, but also human and organizational components. The supervision of certain industrial domains provides a good example of such systems, because although more and more actions for piloting installations are now automatized, there always remains a decision level (at least in the management of degraded modes) involving human behavior and organizations. The field of application of the study presented here is railway traffic supervision, using modern automatic train supervision (ATS) systems. Examples taken from railway traffic supervision illustrate the principal advantage of FRAM in comparison to classical safety analysis models, i.e. their ability to take into account technical as well as human and organizational aspects within a single model, thus allowing a true multidisciplinary cooperation between specialists from the different domains involved.A FRAM analysis is used to interpret experimental results obtained from a real ATS system linked to a railway simulator that places operators (experimental subjects) in simulated situations involving incidents. The first results show a significant dispersion in performances among different operators when detecting incidents. Some subsequent work in progress aims to make these “performance conditions” more homogeneous, mainly by ergonomic modifications. It is clear that the current human-machine interface (HMI) in ATS systems (a legacy of past technologies that used LED displays) has reached its limits and needs to be improved, for example, by highlighting the most pertinent information for a given situation (and, conversely, by removing irrelevant information likely to distract operators).     

密切值法用于纸或纸板的综合性质量评价

采用密切值法对同一等级的5种纸袋的质量进行处理,进而求出各纸袋与最好、最差质量的距离,得到综合评价反映最差和最好质量距离两者水平的综合参数--密切值,并根据密切值的大小进行排序.实例计算表明,密切值法充分全面地考虑了各评价指标之间的影响关系,它用于纸或纸板的质量评价和排序是完全可行的,比传统的一些方法更有效、客观和可靠.     

线阵CCD测量技术在烟草物理检测中的应用

论述线阵CCD技术及其在几何尺寸测量中的应用,对线阵CCD的特点和信号的处理方法进行了较为详细的描述。针对CCD信号二值化这一关键技术,提出了更为合理、精确的算法。并结合这一技术在卷烟厂中有关烟支长度的检测,进一步论述线阵CCD技术在大尺寸测量中的具体应用。     

面向宽带流媒体的接入汇聚路由器中缓冲区容量的选取研究

根据宽带流媒体的突发性和自相似特点及接入汇聚路由器（ACR）对预留宽带的严格控制,建立了用分形布朗运动（FBM）来表示输入流量模型的自相似模型,用其定量分析了ACR中缓冲区容量与分组丢失率的关系。分析结果表明,为支持其有良好服务质量的宽带流媒体业务,必须确保每路视频流的丢失率小于一个定值,在此条件下,所需缓冲压的容量与媒流体的自相似系数及链路平均利用率成正比,在实际工程实践中可以根据系统丢失率的要求计算需要预留的缓冲区容量,以此来保证视频传输的服务质量。     

How to register geographical indications in the European Community

Geographical indications (GIs) are names associated with quality products coming from specific places when the geographical origin of the products gives them specific qualities, characteristics and reputation. Geographical indications are known to be the earliest type of trademarks. Historically, they have existed as long as, if not longer than, trademarks. GIs are intended to highlight special qualities of the products through indication of their origin. They also preserve cultural traditions and, therefore, are rightly associated with protection of traditional knowledge and community rights. Since the consumers appreciate quality goods, the use of GIs allows producers to obtain market recognition and a premium price for their goods. This is one of the reasons why adequate protection of this intellectual property type is required. In the EU, GIs for agricultural products and foodstuffs are protected by EC Regulation 510/2006. In order to be protected in accordance with the Regulation, GIs must be registered. This article briefly explains the nature and benefits of GIs, and explains in more detail the registration system in the EU for European and foreign GIs established by Regulation 510/2006. This issue is significant due to the importance of protection of GIs, as part of the EU quality policy in agriculture. Reference is made to the relevant database for information on EU GIs.