Measurement system for wind turbine acoustic noise assessment based on IEC standard and Qin′s model

A novel measurement system specially used in noise emission assessment and verification of wind turbine generator systems is presented that complies with specifications given in IEC 61400-11 to ensure the process consistency and accuracy. Theory elements of the calculation formula used for the sound power level of wind turbine have been discussed for the first time, and detailed calculation procedure of tonality and audibility integrating narrowband analysis and psychoacoustics is described. With a microphone and two PXI cards inserted into a PC, this system is designed in Qin′s model using VMIDS development system. Benefiting from the virtual instrument architecture, it′s the first time that all assessment process have been integrated into an organic whole, which gives full advantages of its efficiency, price, and facility. Mass experiments show that its assessment results accord with the ones given by MEASNET member.     

Pitch and time, tonality and meter: How do musical dimensions combine?

The authors examined how the structural attributes of tonality and meter influence musical pitch–time relations. Listeners heard a musical context followed by probe events that varied in pitch class and temporal position. Tonal and metric hierarchies contributed additively to the goodness-of-fit of probes, with pitch class exerting a stronger influence than temporal position (Experiment 1), even when listeners attempted to ignore pitch (Experiment 2). Speeded classification tasks confirmed this asymmetry. Temporal classification was biased by tonal stability (Experiment 3), but pitch classification was unaffected by temporal position (Experiment 4). Experiments 5 and 6 ruled out explanations based on the presence of pitch classes and temporal positions in the context, unequal stimulus quantity, and discriminability. The authors discuss how typical Western music biases attention toward pitch and distinguish between dimensional discriminability and salience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition priming in music.

The authors explore priming effects of pitch repetition in music in 3 experiments. Musically untrained participants heard a short melody and sang the last pitch of the melody as quickly as possible. Each experiment manipulated (a) whether or not the tone to be sung (target) was heard earlier in the melody (primed) and (b) the prime-target distance (measured in events). Experiment 1 used variable-length melodies, whereas Experiments 2 and 3 used fixed-length melodies. Experiment 3 changed the timbre of the target tone. In all experiments, fast-responding participants produced repeated tones faster than nonrepeated tones, and this repetition benefit decreased as prime-target distances increased. All participants produced expected tonic endings faster than less expected nontonic endings. Repetition and tonal priming effects are compared with harmonic priming effects in music and with repetition priming effects in language. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Development of Tonal Centres and Abstract Pitch as Categorizations of Pitch Use

Modelling how people establish a sense of tonality and encode pitch invariance are important elements of research into musical cognition. This paper describes simulations of processes that induce classifications of pitch and interval use from a set of nursery-rhyme melodies. The classifications are identified with keys and degrees of the scale. The extractive process has been implemented in various forms of shunting, adding and tracking memory, and ART2 networks, Kohonen feature maps and feedforward nets are used as classifiers, in modular combinations. In the model, stable tonal centres emerge as general categories of pitch use over the short to medium term, while degree categories emerge from classifying interval use over the longer term. The representations of degree reflect the similarity relations between degrees. Overall, this research is concerned with the problem of how to abstract representations of sequences in a way that is both resilient and adaptive. It uses various extractive processes cooperatively to derive consistent representations from sequences of pitches, and shows that by using information generated within one process it is possible to guide the development of another, in this case functional representation.     

低频噪声有调度计算模型分析

对于低频噪声,信号中心频率附近声压级较高的有调音部分发生变化时,包括谱峰的声压级增高和谱峰的形状变尖,会使主观有调感明显提高。因此在考虑有调度计算模型时,一定要充分考虑峰值信号部分产生的影响。现有的有调度计算模型虽然在此部分有所考虑,但是由于模型中的带宽计权因子不能恰当描述这一特征,因而不能准确描述相应的主观感觉,并且计算模型不稳定。通过实验研究与分析得到影响主观有调感最大的因素是有调音部分的声压级大小和谱峰形状,据此进一步从纯音的窄带频率调制信号的主观评价实验出发,通过实验所得的有调度评分值反演出有调度的带宽计权因子,从而对现有模型中的带宽计权因子进行了修正,增加了峰值尖锐程度对有调度的影响,提高了有调度模型的准确性,而且增强了计算的鲁棒性。     

一种基于音调的语音/音乐实时分类算法

语音／音乐的实时分类,在语音／音乐通用编码器中是尤其重要的。分析了语音和音乐的区别性特征,提出了一种利用音调分布特性和频谱倾斜度对语音和音乐进行实时分类的算法,并对分类结果进行简单平滑,使分类更为合理,从而提高音质。实验结果表明,此算法复杂度低,而且分类准确率高,实用性强。     

音乐控制法改善车内声品质的试验研究

以4种类型汽车内采集到的32个不同噪声样本为评价对象,通过试验研究建立了以心理声学客观参数描述主观评价结果的车内声品质模型,并对声品质较差的噪声样本实施了音乐掩蔽控制试验,试验结果表明,车内噪声的低沉度下降,音调度上升。研究结果表明音乐掩蔽控制法用于改善汽车声品质的可行性和有效性。     

Colour tonality inspection using eigenspace features

In industrial quality inspection of colour texture surfaces, such as ceramic tiles or fabrics, it is important to maintain a consistent colour shade or tonality during production. We present a multidimensional histogram method using a novelty detection scheme to inspect the surfaces. The image noise, introduced by the imaging system, is found mainly to affect the chromatic channels. For colour tonality inspection, the difference between images is very subtle and comparison in the noise dominated chromatic channels is error prone. We perform vector-ordered colour smoothing and extract a localised feature vector at each pixel. The resulting histogram represents an encapsulation of local and global information. Principal component analysis (PCA) is performed on this multidimensional feature space of an automatically selected reference image to obtain reliable colour shade features, which results in a reference eigenspace. Then unseen product images are projected onto this eigenspace and compared for tonality defect detection using histogram comparison. The proposed method is compared and evaluated on a data set with groundtruth. Xianghua Xie is currently a Ph.D. student and a research assistant in the Department of Computer Science, University of Bristol, U.K. Prior to this, he received an M.Sc. degree in advanced computing with commendation from the University of Bristol in 2002 and a B.Sc. degree in environmental engineering from the Tongji University, Shanghai, P.R. China, in 2000. His current research interests are texture analysis, image segmentation, surface inspection, deformable models and historical document analysis. He is a student member of the BMVA, the IEE and the IEEE. Majid Mirmehdi received the B.Sc. (Hons.) and Ph.D. degrees in computer science in 1985 and 1991 respectively, from the City University, London. He has worked both in industry and in academia. He is currently a Reader in the Department of Computer Science at the University of Bristol, UK. His research interests include texture analysis, colour image analysis, medical imaging and document recognition. He has over 100 refereed conference and journal publications in these areas. He is an associate editor of the Pattern Analysis and Applications Journal. He is a member of the IEE, IEEE and a member and the Chairman of the British Machine Vision Association.     

改进的风力发电机组噪声音调评估方法

摘要：针对目前风力发电机组（Wind Turbine,WT）噪声音调评估方法的不足,提出了相应的改进方法。首先,采用Gabor阶比分量提取技术从WT运行状态下采集的噪声数据中,提取出与WT本身音调相关的噪声信号,消除了用停机状态下背景噪声修正开机状态下的WT噪声所造成的误差;然后,利用基于转速的最优分割法将一分钟WT噪声信号划分为尽可能平稳的子段信号,避免了由非平稳信号FFT变换引起的频率混叠现象;最后,采用基于谱平面的音调判定法代替IEC标准中基于心理声学模型的音调估计法,消除了初始音调预测的误差并简化了音调辨识的过程。新疆达坂城的试验研究表明,提出的音调改进技术能够消除IEC中音调辨识方法的不确定性和不一致性,在WT的音调噪声评估中具有良好的应用前景。     

色彩设计在网页中的实际应用

色彩是一个网页给人的最初印象.它对网页的可读性、视觉舒适性都会产生极大的影响.本文主要探讨在网页设计中如何进行色彩设计的问题.归纳出了四种常用的色彩设计手段,通过范例讲解了具体操作方法.同时对网页的不同色彩带给浏览者不同的视觉感受进行了简单的论述.