主成分分析在舰船辐射噪声分类识别中的应用

主成分分析(PCA)是经典的多元统计分析方法,在处理多变量综合问题方面有比较突出的优势。本文主要探讨了主成分分析在舰船辐射噪声信号分类识别中的应用。在经典功率谱的基础上尝试将PCA技术运用在两种不同的方法中,对两种舰船辐射噪声进行了特征提取和分类识别,得到了较好的效果。     

Motorway noise modelling based on perpendicular propagation analysis of traffic noise

A model for motorway traffic noise has been obtained from measurements along the the Bangkok-Chonburi motorway. The model’s parameters include traffic volume and combination, the average spot speed of each type of vehicle and the physical conditions of the motorway in terms of right-of-way width, number of lanes, lane width, shoulder width, and median width for both of the main carriageways and frontage roads. The noise level that is generated by each type of vehicle has been analyzed according to the propagation in the direction perpendicular to the center line of motorway’s carriageway. The total traffic noise is then analyzed from traffic volume of all vehicle types on both sides of carriageways and frontage roads. The basic noise levels used in the motorway traffic noise model are modified according to the effective ground effect along the propagation path. The final result of this study is that a motorway traffic noise model based on the perpendicular propagation analysis technique performs well in a statistical goodness-of-fit test against the field data, and therefore, can be used effectively in traffic noise prediction for related or similar motorway projects.     

Influence of expanding ring roads on traffic noise in Beijing City

The road network in Beijing is expanding in the form of loop-lines. Following the 2nd and 3rd ring roads, the 4th has been completed and come into operation in 2002. Traffic noise surveying and analysis was performed along four main roads in the Beijing urban area—the 2nd, 3rd and 4th ring roads circling the central downtown area and Chang-An Avenue, a major east-west corridor through the heart of the city. Measured noise data along the 2nd, 3rd and Chang-An Avenue were compared with the data surveyed before the completion of the 4th ring road for determining influence of expanding ring roads on traffic noise pattern in Beijing City. The results indicate that these main roads remain overloaded by traffic flow during daytime, and noise levels due to road traffic along these roads exceeds relavent environmental standards by 5 dBA. Reduced traffic noise level was observed along the northern half of the 2nd and 3rd ring roads, and along the central section of Chang-An Avenue. Increased traffic noise level was observed along the southern half of the 2nd and 3rd ring roads, and along the non-central section of Chang-An Avenue. Expanding ring roads mitigate heavy traffic flow in the central part of Beijing City, but spread high traffic noise outwards at the same time.     

A simple formula for evaluating the acoustic effect of balconies in protecting dwellings against road traffic noise

This study explores the noise reducing effect of a balcony and describes the development of a simple theory pertaining to the propagation of traffic noise from a road into a balcony. A new methodology is proposed that is based on the well-known prediction scheme—“Calculation of Road Traffic Noise” (CRTN)—developed in the UK. A geometrical ray theory is developed for the prediction of noise levels inside a balcony due to road traffic. The source level of road traffic noise is obtained as per the standard CRTN methodology. However, road sub-segmentations and new approaches for the prediction of noise levels at illuminated and shadow zones inside a balcony are proposed. Field measurements have been conducted on four different types of balcony to validate the proposed methodology. The insertion loss, defined as the difference in the noise levels with and without the presence of a balcony, has been used to assess the shielding effectiveness of a balcony against road traffic noise. The simple theory is validated by outdoor field measurements. It is also found that a properly designed balcony can provide considerable screening effects in protecting dwellings against road traffic noise.     

Effects of traffic noise on paserine populations in Mediterranean wooded pastures

The effect of traffic noise on the breeding density of 20 passerine species was examined over a 2-year period in three different road types passing through pasture-woodlands in western-central Spain. No statistically significant differences were observed during the 2 years studied. An average of 19.6 birds/10 ha was recorded for the low-traffic road (LT), 21.7 birds/10 ha for the medium-traffic road (MT) and 19.1 birds/10 ha for the high-traffic road (HT). A total of 11 species (55%) did not show any statistically significant differences in breeding density among the different types of roads. By contrast, other species, such as the Blackbird, the Iberian Shrike and the Linnet, did point to differences between the MT and HT roads. House and Rock Sparrows, as well as the Corn Bunting, showed higher breeding densities near the HT road. The opposite effect was observed for the Wheatear, the Iberian chiffchaff and the Woodlark, for which high breeding densities were recorded in the vicinity of the LT road. Our results suggest that traffic noise constitutes a serious problem for at least 15% of the breeding bird community.     

主成分分析结合感知器在医学光谱分类中的应用

基于光谱分析技术的经典理论,应用主成分分析方法对83例(癌症42,非癌41)乳腺患者病理片的紫外吸收光谱进行主成分提取.选用其中44例(癌症22,非癌22)作为训练样本,其余的39例(癌症20,非癌19)作为测试样本,将其主成分数据作为输入向量分别对离散型和连续型感知器神经网络模型进行训练和测试.通过对比发现:离散型感知器模型由于其输出函数值只有{0,1}且算法较为简单,其癌症识别率只有43.3%,非癌识别率为38.7%;而连续型感知器模型将模糊集合理论引进了神经网络系统,将二值{0,1)扩展到隶属度函数的单位区间[0,1]上,结果表明这种模型的癌症识别率为83.6%,非癌的识别率为76.3%,取得了较为理想的识别效果.     

Effects of urban morphology on the traffic noise distribution through noise mapping: A comparative study between UK and China

Due to the rapid urban development and massive population increase in many eastern cities, the difference in urban density and morphology between typical western and eastern cities is becoming significant. This consequently makes the noise distribution in the eastern cities rather different from typical low density European cities. In this research, two representative cities with different urban densities, Greater Manchester in the UK and Wuhan in China, were selected, which have low and high average urban density respectively, and also have considerable differences in building form and traffic pattern. In the mean time, these two cities have similar urban scale and traffic amount. In each city, based on the urban morphological analyses considering urban land-use, building and road density, and noise source distribution, a number of typical urban areas, 500 * 500 m² each, were sampled. A noise-mapping software package was then used to generate generic noise maps, based on existing digital vector maps for terrain and building, and traffic data obtained by on-site measurements. The comparison results show that the average and minimum noise level in Greater Manchester samples is generally higher than that in Wuhan samples, while the maximum noise level in Wuhan samples is mostly higher. By developing a Matlab program, correlations have been analysed between noise distributions and the urban characteristics relating to urban density, such as the road and building coverage ratio. Overall, comparisons between these two typical cities have shown significant effects of urban morphology on the traffic noise distribution.     

Complexity reduced coding of binary pattern units in image classification

The ability to simulate and control complex physical situations in real time is an important element of many engineering and robotics applications, including pattern recognition and image classification. One of the ways to meet specific requirements of a process is a reduction of computational complexity of algorithms. In this work we propose a new coding of binary pattern units (BPU) that reduces the time and spatial complexity of algorithms of image classification significantly. We apply this coding to a particular but important case of the coordinated clusters representation (CCR) of images. This algorithm reduces the dimension of the CCR feature space and, as a consequence, the time and space complexity of the CCR based methods of image classification, exponentially. In addition, the new coding preserves all the fundamental properties of the CCR that are successfully used in the recognition, classification and segmentation of texture images. The same approach to the coding of BPUs can be used in the Local Binary Pattern (LBP) method. In order to evaluate the reduction of time and space complexity, we did an experiment on multiclass classification of images using the “traditional” and the new coding of the CCR. This test showed very effective reduction of the computing time and required computer memory with the use of the new coding of BPUs of the CCR, retaining 100% or a little less efficiency of classification at the time.     

改善船舰噪声听觉辨识的特征注入法

为提高声纳员对舰船噪声的听测识别水平,本文提出了特征注入法及其实现方法。该方法通过对指定子带重构、子带加权重构和特征子带注入法三个核心环节的建模仿真,对船舰噪声进行重构,进而对重构后的舰船噪声进行听测识别和谱分析,并根据分析结果对重构方案进一步优化调整。结果表明,采用合理重构方案的特征注入法能有效改善人耳的听测辨识效果。     

Estimation of increases in noise levels due to installation of transverse rumble strips on urban roads

Increases in noise due to the installation of transverse rumble strips were investigated, by first measuring noise due single vehicles crossing a pilot test field with and without a rumble strip. After that, a procedure was proposed and carried out to estimate increases in noise due to the traffic of vehicles, based on the measurements previously mentioned. This procedure was checked against expressions from the literature that estimate traffic noise as well as measurements in three arterial urban roads without rumble strips installed. Its accuracy was compatible with the ones obtained by applying the literature expressions, the errors lying below 3 dB(A). Then, by taking the aforementioned roads as case studies, estimations were carried out for the increases that would occur in noise levels if rumble strips were installed on them, leading to values between 6 and 7 dB(A). Although such values are dependent on the configuration of the rumble strip employed, the proposed procedure presents generality and could be applied to estimate increases in traffic noise due to installation of rumble strips, by departing from measurements of noise due to single vehicles obtained for a given rumble strip configuration.     

Self-organized patterns and traffic flow in Colonies of organisms: from bacteria and social insects to vertebrates

Flocks of birds and schools of fish are familiar examples of spatial patterns formed by living organisms. In contrast to the patterns on the skins of, say, zebras and giraffes, the patterns of our interest are transient although different patterns change over different timescales. The aesthetic beauty of these patterns has attracted the attention of poets and philosophers for centuries. Scientists from various disciplines, however, are in search of common underlying principles that give rise to the transient patterns in colonies of organisms. Such patterns are observed not only in colonies of organisms as simple as single-cell bacteria, but also in social insects like ants and termites. They are also observed in colonies of vertebrates as complex as birds and fish, and in human societies. In recent years, physicists have utilized the framework of statistical physics to understand these patterns. In this article, we present an overview emphasizing the common trends that rely on theoretical modeling of these systems using the so-called agent-based Lagrangian approach.     

Application of multi-channel spectral analysis to identify the source of a noise amplitude modulation in a diesel engine operating at idle

We are interested in the low frequency amplitude modulation of the noise generated by an engine operating at idle. This phenomenon, perceived inside the car, is particularly annoying. Modulated vibrations are transmitted to the frame mainly by one of the three engine mounts. The combustion is the first potential source to be inspected, but pragmatic observations on consecutive measurements show that it is not the cause of the amplitude modulation. Spectral analysis tools are applied on multi-channel measurements to identify the source of the phenomenon. A sensor is placed on each potential noise and vibration source. A virtual source analysis show that several uncorrelated sources are contributing to the operating response, particularly on frequencies for which a high amplitude modulation is observed. The computation of residual spectra obtained by means of conditioned spectral analysis proves that the diesel pump is involved in the amplitude modulation. Experiments are carried out to validate this diagnosis. Added masses appropriately placed on the injection circuit strongly attenuate the phenomenon.     

Real-time acoustic classification of sperm whale clicks and shipping impulses from deep-sea observatories

The automated real-time detection and classification of cetacean and anthropogenic sounds from deep-sea observatories can play a key role to study cetaceans in the field, to quantify the impact of anthropogenic sounds or to initiate mitigation measures during potentially harmful human activities. In the area of the NEMO-ONDE deep-sea observatory, sperm whales are often present together with heavy shipping. The spatial coincidence of both sound sources allows for the long term monitoring of their interaction. Some ships produce impulsive sounds and the automated separation of these impulses from sperm whale clicks is not a trivial task. As part of a detection, classification and localisation system for acoustic data from marine observatories, we present four modules performing the automated real-time classification of clicks from sperm whales and impulsive sounds produced by ships. First, two modules detect segments that contain impulsive sounds within a specifiable frequency band and return the impulses’ positions. Then, two modules classify the detected impulses as sperm whale clicks or ship impulses. Finally, at the level of 22 s segments, the classification outputs from individual impulses are combined into a decision on the presence of sperm whale clicks or ship impulses. The modules’ reliability was tested on data from the NEMO-ONDE observatory. Training and testing data were separated by more than 2 months, enabling to assess the consistency of the predictions over the long term. The automated separation between segments of the two classes was high with area under the ROC curve (AUC) values between 0.94 and 0.98.     

Simultaneous use of amplitude and phase to improve the validation process in a joint transform correlator

We present an alternative technique to enhance the discrimination performance in a JTC architecture, employed as a validation procedure. We define as complex objects those amplitude objects bonded to random phase masks. When using complex objects as reference inputs in a JTC optical validation system, correlation peak intensity and correlation peak shape become simultaneous key parameters to increase the discrimination ability of the system. Simulation results, comparing amplitude-only objects versus complex objects as inputs to the system, reveal the validity of our approach and show the sensitivity of the JTC architecture to the additional phase structures.     

Detection of functional states by the ‘LAMDA’ classification technique: application to a coagulation process in drinking water treatment

The present Note proposes a learning classification methodology to identify functional states on a coagulation process involved in drinking water treatment. In this work, we chose to carry out the supervised control of this process while using the LAMDA (Learning Algorithm for Multivariate Data Analysis) classification technique. The LAMDA classification technique proposes the interactive participation of the expert operator during the learning phase and in the optimisation of the classification. In this work, all information stemming from the environment process as well as expert knowledge has been aggregated and exploited. The application chosen for state identification is the Rocade drinking water treatment plant located at Marrakech, Morocco. To cite this article: B. Lamrini et al., C. R. Physique 6 (2005).     

Converting the UK calculation of road traffic noise (CORTN) to a model capable of calculating LAeq,1h for the Tehran’s roads

This paper describes the methodology through which the UK calculation of road traffic noise (CORTN) has been converted to the algorithms that are able to calculate hourly A-weighted equivalent sound pressure level (L_Aeq,1h) for the Tehran’s roads. The methodology adopts two different approaches to model calibration and performance test through the holdout validation method on the basis of the database including 52 samples taken from 52 sampling stations located alongside 5 roads of Tehran at distances less than 4 m from the nearside carriageway edge. As to the CORTN manual the distances less than 4 m are considered to be equal to 4 m. In the first approach the model is calibrated through carrying out nonlinear regression parameter estimation using 50% of samples to replace the basic noise level parameters with the new ones that are presumably able to satisfy the objective of the study with an acceptable fitness of the model. In the second approach the model calibration is carried out on the basis of 30 measurements taken from 2 roads. In the next step the other subsets of samples are introduced into the calibrated equations to conduct the performance test. Non parametric goodness of fit tests, i.e. two related samples Wilcoxon and two independent samples Kolmogorov-Smirnov, respectively conducted for the calibration and the performance test steps; indicate satisfactory results for both approaches.