纳米尺度MOSFET过剩噪声的定性分析

最近实验表明纳米尺度MOSFET中的过剩噪声主要为散粒噪声,而此前研究认为MOSFET中不存在散粒噪声,短沟道MOSFET中的过剩噪声为热噪声. 本文基于器件电流模型分析散粒噪声取代热噪声成为过剩噪声主要成分的转变条件,根据该条件对纳米尺度MOSFET噪声特性的预测与文献报道的实验现象、模拟结果以及介观散粒噪声相关结论相符合. 关键词： 散粒噪声 过剩噪声 纳米尺度MOSFET     

光电耦合器件1/f噪声和g-r噪声的机理研究

对光电耦合器件1/f噪声和g-r噪声(产生－复合噪声) 的偏置特性及其产生机理进行了实验和理论研究.结果表明：在低频段,光电耦合器件的g-r噪声通常表现为叠加1/f噪声,且两者均随输入电流的增加呈现先增大后减小的规律.通过测量前级噪声和后级噪声,发现光电耦合器件的g-r噪声源为后级光敏三极管.理论分析表明：光电耦合器件的1/f噪声主要为表面1/f噪声,g-r噪声则源于光敏三极管发射结空间电荷区的深能级对载流子的俘获和发射.     

环境噪声对儿童短时记忆力和注意力的影响

通过实验室研究探讨了不同噪声源在不同声压级条件下对儿童短时记忆力和注意力的影响。在每一个实验中都选取了30名710岁的儿童作为被试,在他们完成相应认知任务的同时,用耳机随机播放3565 dBA的交通噪声、白噪声和空调噪声,考察各种噪声条件对被试认知成绩和主观烦恼度的影响。研究结果表明,噪声对儿童的影响主要体现在主观烦恼度的变化上,不同的噪声条件并没有引起作业成绩的显著差异。影响儿童主观烦恼度的主要因素是声压级,随着声压级的增大,儿童的烦恼度会增加,当声压级在4550 dBA时,儿童对噪声开始产生烦恼感,当声压级在6065 dBA时,儿童对噪声产生了较显著的烦恼感。声压级对儿童烦恼度的影响没有随着噪声源的改变而改变。在相同的噪声条件下,短时记忆力实验中儿童的主观烦恼度都高于注意力实验,说明随着认知过程复杂程度的增加,噪声引起的烦恼度会相应增加。      

Correlated noise induced spatiotemporal coherence resonance in a square lattice network

The effects of additive correlated noise, which is composed of common Gaussian white noise and local Gaussian colored noise, on a square lattice network locally modelled by the Rulkov map are studied. We focus on the ability of noise to induce pattern formation in a resonant manner. It is shown that local Gaussian colored noise is able to induce pattern formation, which is more coherent at some noise intensity or correlation time, so it is able to induce spatiotemporal coherence resonance in the network. When common Gaussian white noise is applied in addition, it is seen that the correlated noise can induce coherent spatial structures at some intermediate noise correlation, while this is not the case for smaller and larger noise intensities. The mechanism of the observed spatiotemporal coherence resonance is discussed. It is also found that the correlation time of local colored noise has no evident effect on the optimal value of the noise strength for spatiotemporal coherence resonance in the network.     

An analysis of quasi-frequency-modulated noise and random-sideband noise as comparisons for amplitude-modulated noise

Experiments were performed to determine under what conditions quasi-frequency-modulated (QFM) noise and random-sideband noise are suitable comparisons for AM noise in measuring a temporal modulation transfer function (TMTF). Thresholds were measured for discrimination of QFM from random-sideband noise and AM from QFM noise as a function of sideband separation. In the first experiment, the upper spectral edge of the noise stimuli was at 2400 Hz and the bandwidth was 1600 Hz. For sideband separations up to 256 Hz, at threshold sideband levels for discriminating AM from QFM noise, QFM was indiscriminable from random-sideband noise. For the largest sideband separation used (512 Hz), listeners may have used within-stimulus envelope correlation in the QFM noise to discriminate it from the random-sideband noise. Results when stimulus bandwidth was varied suggest that listeners were able to use this cue when the carrier was wider than a critical band, and the sideband separation approached the carrier bandwidth. Within-stimulus envelope correlation was also present in AM noise, and thus QFM noise was a suitable comparison because it made this cue unusable and forced listeners to use across-stimulus envelope differences. When the carrier bandwidth was less than a critical band or was wideband, QFM noise and random-sideband noise were equally suitable comparisons for AM noise. When discrimination thresholds for QFM and random-sideband noise were converted to modulation depth and modulation frequency, they were nearly identical to those for discrimination of AM from QFM noise, suggesting that listeners were using amplitude modulation cues in both cases.     

Inquiry on noise causing complaints in residential areas near chemical plants

Industrial noise may lead to noise annoyance in residential areas, in particular when such areas are located close to industrial plants. Specific reduction of noise requires detailed knowledge of the complaints from the residential neighbourhood and their relation to the noise source.The membership companies of the German Federation of Chemical Industry have recorded 230 noise complaints from 1977 to 1979. In relation to these complaints, parameters, e.g. nature of noise source, noise character, time of noise occurrence, meteorological conditions, were investigated and statistically evaluated.Fifty complaints out of the 230 were quantitatively evaluated with respect to the background and noise level at the location of complaint. It resulted, that only 16% of the complaints are based on broad band noise, whereas 84% on impulse noise and single tones. Broad band noise causes complaints beginning at 65 dB(A), impulse noise at 56 dB(A) and single tones at 50 dB(A).     

填充系数对脉冲爆轰发动机爆轰噪声影响的实验研究

为探索不同填充系数下气液两相脉冲爆轰发动机爆轰噪声特点,搭建了能够准确调节气液两相脉冲爆轰发动机填充系数的噪声测试实验系统,对800 mm和3000 mm处不同角度下脉冲爆轰发动机爆轰噪声特性进行了研究。结果表明,随着填充系数的增加,冲击噪声幅值与射流噪声幅值随之增大,但射流噪声幅值与冲击噪声幅值的比值降低;在爆燃与爆轰的转折点,冲击噪声幅值与射流噪声幅值显著增加;爆燃阶段下的冲击噪声幅值与射流噪声幅值增加速率小于爆轰阶段;随着距离的增加,填充系数对冲击噪声与射流噪声的增强作用有所减弱,冲击噪声的衰减速度快于射流噪声;随着填充系数的增加,当距离较小时指向性明显,当距离较大时指向性不明显。      

基于改进中值滤波和提升小波变换的阈值去噪方法研究

对于实际拍摄的一些图像信噪比低,噪声密度大,且含有混合噪声,而现有算法大多只能去除单一噪声的问题。针对混合噪声中含有的脉冲噪声和高斯噪声,提出基于改进中值滤波和提升小波变换去噪相结合的方法。去噪过程中,使用中值滤波器提取脉冲噪声并采用中值滤波算法滤波后,构造提升小波,采用改进阈值函数提升小波阈值去噪方法去除高斯噪声。实验结果表明,当噪声值(,)=(0.4, 20)时,采用本文去噪方法,峰值信噪比（PSNR）为34.002 1,平均绝对误差（MAE）为2.365 3。     

Predicting the noise level in rock sawing from the physico-mechanical and mineralogical properties of rocks

Millions of employees in the World are exposed to noise at work. Block cutting machine is one of the most important noise sources in the stone processing plants. In this study, the predictability of the noise from the block cutting machines in the stone processing plants was investigated by using the physico-mechanical and mineralogical properties of rocks. The noise levels of some block cutting machines were firstly measured during the cutting of the three different rocks. Then, the core samples of the same rocks were cut by an automatic cutting machine in the laboratory and the noise levels were measured. A conversion factor was obtained by dividing the site noise levels by the laboratory noise levels. Then, nineteen different rocks were cut by the automatic cutting machine in the laboratory and the noise levels were measured. Strong correlations were found between the laboratory noise level and the rock properties. The noise level increases with increasing rock strength, abrasive mineral content, and density. However, increasing porosity decreases the noise level. It was concluded that the laboratory noise level for a new rock type to be cut can be estimated using the derived relations. Then, the laboratory noise level can be converted to the site noise level using the derived conversion factor.     

光纤1/f热噪声的实验研究

光纤热噪声是限制光纤传感、测量系统性能的最终因素.但是低频区域呈1/f谱特性的光纤热噪声的形成机制迄今仍然存在争论.实验研究了光纤1/f热噪声水平与光纤内杂质离子浓度和光纤施加张力的关系,验证了这类热噪声来源于光纤内部的机械耗散引起的长度自发抖动,符合热机械噪声的理论假设.     

The correlation between intrinsic noise and extrinsic noise

The correlation between intrinsic noise and extrinsic noise in a stochastic system is reviewed in this paper. And the contribution of the correlation between intrinsic noise and extrinsic noise to the power spectrum is quantified by simulation through a model in a stochastic system. In addition, the effects of the correlations between intrinsic noise and extrinsic noise to the power spectrum are analyzed clearly. Finally, it is shown that our results can be used to describe the transmission of the noise in modules in more complex stochastic systems.     

The role of noise sensitivity in the noise-response relation: a comparison of three international airport studies

In order to examine the role of noise sensitivity in response to environmental noise, this paper presents detailed comparisons of socio-acoustic studies conducted around international airports in Amsterdam, Sydney, and London. Earlier findings that noise sensitivity moderates the effect of noise on annoyance were examined to see if they could be replicated in each of the datasets, independent of the technique of measuring noise sensitivity. The relation between exposure to aircraft noise and noise annoyance was studied separately for groups of individuals with low, medium, and high noise sensitivity, with statistical adjustment for relevant confounders. Results support the previous findings that noise sensitivity is an independent predictor of annoyance and adds to the prediction of noise annoyance afforded by noise exposure level by up to 26% of explained variance. There is no evidence of a moderating effect, whereby the covariation between noise exposure level and annoyance is weak for people who score at the extreme high or low end of the sensitivity scale, and strong for people who score in the middle of the sensitivity scale. Generally, noise sensitivity appears to increase annoyance independently of the level of noise exposure after adjustment for relevant confounders. These findings were consistent across the three datasets.     

基于搜索平均法的气象观测数据的非线性去噪

介绍了一种新型基于相空间重构和返回图法的非线性降噪方法——搜索平均法，首先将该方法应用于被高斯白噪声所污染的Henon映射时间序列，说明根据降噪理论所编写的计算程序的正确性；然后应用于中国气象局公布全国435站1960—2000年的逐日气温观测时间序列，并利用非线性预报方法衡量降噪的效果，验证了该方法的有效性.     

隧穿磁电阻效应磁场传感器中低频噪声的测量与研究

基于隧穿磁电阻效应(TMR)的磁场传感器具有很高的磁场灵敏度, 但同时噪声也较大,有效抑制TMR磁场传感器的噪声, 尤其是低频噪声的抑制对于其在高灵敏度要求场合的应用具有重要的意义. 本文采用高精度数据采集卡搭建了噪声测量系统, 测量了全桥结构TMR磁场传感器的噪声频谱图, 发现TMR传感器的噪声在低频段表现为1/f特性, 同时噪声功率谱密度与工作电流平方成正比关系; 低频噪声在自由层翻转区间内噪声急剧增大, 证明了1/f噪声主要来源于磁噪声, 这一结果为TMR磁场传感器的噪声特性优化指明了方向.     

Sleep disturbance effects of traffic noise—A laboratory study on after effects

Body movements during sleep and subjective sleep quality, as well as mood and performance were investigated after exposure to intermittent and continuous traffic noise during the night. In a first experiment, six young subjects slept in the laboratory for five nights; in a second experiment 12 subjects slept six consecutive nights in the laboratory. A good dose-response relationship was obtained between intermittent noise and subjective sleep quality: i.e., the higher the noise level, the poorer the sleep quality. A similar dose-response relationship was found for body movements immediately following noise peaks during nights with intermittent noise. Performance and mood tended to be worse after intermittent noise. However, these effects did not increase with an increase in noise levels. Compared with intermittent noise, continuous noise had a significantly smaller effect on sleep quality. Mood and performance were not worse after continuous noise. The results suggest that increased attention should be paid to peak noise levels when standards for nocturnal noise are set.     

Viewing the noise propagation mechanism in a unidirectional transition cascade from the perspective of stability

Noise and noise propagation are inevitable and play a constructive role in various biological processes. The stability of cell homeostasis is also a critical issue. In the unidirectional transition cascade of colon cells, stem cells (SCs) are the source. They differentiate into transit-amplifying cells (TACs), and TACs differentiate into fully differentiated cells (FDCs). Two differentiation processes are irreversible. The stability factor is introduced so that the noise propagation mechanism from the perspective of stability is studied according to the noise propagation formulas. It is found that the value of the stability factor corresponding to the minimum noise in FDCs may be the best choice to enable colon cells to maintain high stability and low noise of the cascade. Moreover, for the source cell, the total noise only includes intrinsic noise; for the downstream cell with self-proliferation capability, the total noise mainly depends on its intrinsic noise and transmitted noise from upstream cells, and its intrinsic noise is dominant. For the downstream cell without self-proliferation capability, the total noise is mainly determined by transmitted noises from upstream cells, and there is a minimum value. This work provides a new approach for studying the mechanism of noise propagation while considering the stability of cell homeostasis in biological systems.     

Decision-based adaptive morphological filter for fixed-value impulse noise removal

A novel adaptive switching morphological filter for removing fixed-value impulse noise is proposed. The proposed filter firstly identifies noise pixels using the two-stage morphological noise detector, in which the initial noise detection is used to identify the noise candidates based on the morphological gradients and the refined noise detection based on the combined conditional morphological operators is adopted to further classify the noise candidates as the noise pixels or noise-free pixels. Then the detected noise pixels are removed by the adaptive morphological filter using the conditional rank-order morphological operators while the noise-free pixels are left unaltered. Extensive simulations show that the proposed filter outperforms a number of existing switching-based filters because of its excellent performance in terms of noise detection and image restoration.     

Preferred listening level for speech disturbed by fluctuating noise

This paper is a sequel to an earlier one in which we investigated, among other things, the influence of stationary background noise on preferred listening level. The influence of fluctuations in noise level on preferred listening level was compared with the influence of stationary noise. It turned out that the preferred listening level for a read-aloud text, adjusted by listeners against a background of noise, is hardly influenced by fluctuations in the noise, provided the equivalent noise level (L_eq) in dB(A) remains the same. This holds both for systematically modulated noise down to 0·1 Hz and more randomly fluctuating noise such as traffic noise. Average preferred listening level proved to be an accurate measure for evaluating various conditions, such as modulation frequency and noise level, in a single experiment.     

Noise impact assessment by utilizing noise map and GIS: A case study in the city of Chungju, Republic of Korea

In this study, a scheme to develop a noise map and noise impact assessment method using GIS has been suggested. After developing a road-traffic noise map for the city of Chungju, Republic of Korea, noise impact assessment was performed through analyzing the map. A 3-dimensional terrain model was generated using digital maps and building models were prepared using the information from draft and digital maps. To develop a noise evaluation model, a noise-source map for each road was generated. The noise levels at 25 locations close to roads were measured and compared with the expected noise levels to verify the developed noise map. An excess noise map was generated by comparing the road-traffic noise map with a noise-standard map. Using the excess noise map, the areas exceeding environmental noise standards were effectively evaluated through a GIS space analysis. The 3-dimensional facade noise map was generated to calculate the number of people exposed to a certain noise level.     

Effect of background noise levels on community annoyance from aircraft noise

A study of community annoyance caused by exposures to civil aircraft noise was carried out in 20 sites around Gimpo and Gimhae international airports to investigate the effect of background noise in terms of dose-effect relationships between aircraft noise levels and annoyance responses under real conditions. Aircraft noise levels were mainly measured using airport noise monitoring systems, B&K type 3597. Social surveys were administered to people living within 100 m of noise measurement sites. The question relating to the annoyance of aircraft noise was answered on an 11-point numerical scale. The randomly selected respondents, who were aged between 18 and 70 years, completed the questionnaire independently. In total, 753 respondents participated in social surveys. The result shows that annoyance responses in low background noise regions are much higher than those in high background noise regions, even though aircraft noise levels are the same. It can be concluded that the background noise level is one of the important factors on the estimation of community annoyance from aircraft noise exposure.