压制干扰噪声质量数字测定方法研究

为了检验压制噪声干扰机的性能,研究了基于实际噪声样本数据的噪声质量测定方法。通过跟踪噪声干扰技术的最新进展,深入分析Turner、Daly和Taylor提出的三种噪声质量度量方法的基本原理及各自存在的局限性,提出一种改进的噪声质量数字测定方法。该方法继承了Turner噪声质量在时域度量噪声概率密度函数高斯性科学有效的特点,加入一种新的频域噪声功率谱密度均匀性度量的罚函数,解决了Daly频域罚函数低精确性和Taylor频域罚函数的不合理性。仿真结果表明,新提出的噪声质量数字测定方法能够有效克服目前其他几种方法的缺陷,有效地测定包括数字灵巧噪声在内的各种压制干扰噪声的质量系数。

呼和浩特市城市噪声质量现状评价

本文对呼和浩特市的城市区域噪声、道路交通噪声及工业企业噪声这三方面监测数据进行分析,对该市的声环境质量现状进行评价,并对连续两年的结果进行比较说明。通过评价表明呼和浩特市城市区域噪声等级为一般;工业企业噪声的排放基本符合国家规定的3类环境功能区的要求;道路交通噪声的超标路段较长,需进一步改善噪声质量现状。本文还针对呼和浩特市的噪声水平,提出了可行的治理措施。

徐州市1990年环境噪声质量状况

噪声污染是当代世界三大污染之一,并且随着近代工业、交通运输和城市建设的发展,人口不断地增加,城市噪声污染问题变得更加突出。由于我市特殊的地理位置及与外部的经济联系,噪声污染防治工作在我市的环境保护工作中也是重要的一个方面。

ICU患者实施噪声质量管理的效果分析

目的对ICU患者实施噪声质量管理,探讨噪声质量管理的临床可行性。方法采用随机对照试验方法,便利抽样法选取2021年4月至2023年3月在上海市奉贤区中心医院ICU治疗的240例患者为研究对象,按照入院时间分组,2021年4月至2022年3月入院的120例患者为对照组,2022年4月至2023年3月入院的120例患者为干预组,对照组给予常规护理,干预组在常规护理的基础上实施噪声质量管理,比较2组的噪声分贝值、睡眠质量、谵妄发生率及患者满意度。结果干预组患者男69例,女51例,年龄(56.08±5.74)岁;对照组患者男68例,女52例,年龄(56.11±5.72)岁。干预组ICU白天和夜晚的噪声分贝值分别为(42.62±1.33)、(38.72±1.28)dB,低于对照组的(67.49±2.36)、(59.65±2.37)dB,差异均有统计学意义(t=100.57、85.12,均P<0.05);干预组患者睡眠质量总分为(78.40±5.86)分,高于对照组的(60.49±6.25)分,差异有统计学意义(t=24.32,P<0.05);干预组患者谵妄发生率为12.50%(15/120),低于对照组的26.67%(32/120),差异有统计学意义(χ^(2)=7.65,P<0.05);干预组患者满意度为97.50%(117/120),高于对照组的90.00%(108/120),差异有统计学意义(χ^(2)=5.76,P<0.05)。结论ICU患者应用噪声质量管理,有利于改善病房整体环境,改善患者睡眠质量,降低患者谵妄的发生,提高患者满意度。

基于CSF和仿射重建模型的噪声图像质量评价

针对无参考噪声图像质量评价问题,提出基于视觉对比度敏感函数(CSF)和仿射重建模型的噪声图像质量评价方法.引入CSF对待评价噪声图像进行滤波,利用图像分块技术,建立基于最优化问题求解的仿射重建模型,得到图像信号成分,估计出残差信号图像.计算各分块的噪声强度点分布,选取噪声强度点数量分布最多的区间,最终的噪声图像质量评价算子由该强度区间内的所有强度点的均值计算得到.在LIVE、TID2008及CSIQ数据库上开展评价算法主客观一致性评估实验,与其他几种评价算法进行对比,比较算法客观评价性能的表现.实验结果表明,提出的算法具有很好的准确性和主客观评价一致性.

基于小波域峰态值的无参考噪声图像评价算法

随机散布在自然图像里的噪声失真一般会破坏图像的原始概率密度分布。研究发现,无失真自然图像和它对应的噪声图像在离散小波变换(Discrete Wavelet Transform,DWT)系数分布上有很大区别:对于自然图像,其DWT系数分布比较尖锐,峰值高,拖尾短;对于噪声图像,其系数分布则比较扁平,峰值低,拖尾长。作为一种常用的统计特征描述,峰态值可以度量和区分不同失真程度的噪声图像的DWT系数分布,而且,DWT系数分布的峰态值具有很好的频率尺度不变性。基于以上特性,提出了一种无参考噪声图像质量评价模型(Blind Noisy Image Quality Assessment model using Kurtosis,BNIQAK)。实验测试了三个最大的质量评价图像库中的五种噪声失真图像,结果表明,和现有无参考噪声评价模型、一般无参考评价模型和全参考(Full-Reference,FR)评价模型相比,BNIQAK具有更好的评价效果。

浅析城市噪声对中学校园的干扰类型及其防治

以铁岭市银州区为例,根据对市区8所中学校园所受的周边环境噪声干扰的监测结果,运用系统聚类分析方法,将其噪声质量划分为3个等级。并分析了噪声干扰的成因,提出防治方法。

河南省新乡县小冀镇环境噪声的测量与分析

为了了解河南省新乡县小冀镇的环境噪声现状,在小冀镇进行了环境噪声监测,根据监测结果绘制了小冀镇白天环境噪声等值线图,分析了该镇白天环境噪声分布情况和主要的噪声源及噪声污染程度。研究结果显示,小冀镇白天的环境噪声分布于50~95 dB (A)之间,噪声来源以交通噪声和生活噪声为主,大部分区域环境噪声质量处于坏–恶化的级别,只有少数区域噪声环境一般,提出了减少和降低噪声污染的措施,为环境主管部门决策提供科学依据。

无为县城区环境噪声空间分布特征研究

为了了解无为县的环境噪声现状,在无为县进行了环境噪声监测,根据监测结果绘制了无为县白天三个时段的环境噪声等值线图,分析了研究区白天环境噪声分布情况和噪声污染程度,利用公路交通噪声预测模型对无为县主要交通噪声进行了预测.研究结果显示,无为县白天的环境噪声值分布于45.0dB^78.4dB之间,大部分区域环境噪声质量处于坏-恶化的级别,只有少数区域噪声环境较好,选用的公路交通噪声预测模型适用于无为县公路噪声的预测,预测结果显示无为县晚间最大交通噪声值为73.0dB.

含时滞反馈与涨落质量的记忆阻尼系统的随机共振

针对具有记忆效应的欠阻尼系统,存在时滞反馈与涨落质量,本文主要研究了其输出稳态响应振幅的随机共振效应.首先通过引入新变量和运用小时滞近似展开理论,将具有非马尔科夫特性的原系统转化为等价的两维马尔科夫线性系统,再利用Shapiro-Loginov公式和Laplace变换获得了系统响应的一阶稳态矩和稳态响应振幅的解析表达式.结果表明:当系统参数满足Routh-Hurwitz稳定条件时,稳态响应振幅随质量涨落噪声强度、周期驱动信号频率以及时滞的变化均存在随机共振现象,其中随机多共振现象也被观察到.在适当范围内,通过控制时滞反馈,系统的随机共振效应随着时滞的增大而增强,而较长的记忆时间及增大阻尼参数均对共振行为呈现抑制作用.有效调控时滞反馈与记忆效应的变化关系将有助于增强系统对周期驱动信号的响应强度.最后,通过数值模拟计算验证了理论结果的有效性.

顾客体验之于新产品供应链协调的影响

新产品引入市场时,其内在价值很难判断,顾客体验能够降低其接受产品的风险.研究了外生体验与内生体验对供应链协调的影响.考虑了销售补偿合同与回购合同,其中,销售补偿合同是供应商对销售商已销售的产品给予补偿,而回购合同是对未销售的产品进行补偿.结论表明,提升外生体验,即顾客收到的噪声信号质量较高,销售商能制定更高的销售价格,供应链协调利润、供应商利润与销售商利润均增加;相反,提升内生体验,即顾客得到的退货补偿越大,供应链协调利润与供应商利润均减少.销售补偿合同不能协调供应链;而回购合同能协调供应链,并且供应商与销售商通过协商批发价格能任意分割供应链利润.

320排CT冠状动脉成像:100 kV对不同体质量者图像质量、噪声及剂量的影响

目的探讨100 kV对不同体质量者320排CT冠状动脉成像(CTCA)图像质量、噪声及剂量的影响。方法连续搜集采用100 kV进行320排CT冠状动脉成像检查者472例,男254例,女218例,平均年龄(60.5±12.2)岁。其中15例心律不齐,4例频发早搏。心率<65次/min者,曝光70%～80%R-R时间窗;心率>65次/min者,曝光30%～80%R-R时间窗。按体重指数(BMI)<20 kg/m2、20 kg/m2≤BMI≤25 kg/m2、25 kg/m2<BMI≤30 kg/m2分为3组。图像质量采用双盲5分评分法(1分为不能诊断,5分为图像质量优),并计算有效辐射剂量(ED)。以感兴趣区(ROI)大小为2 cm×2 cm进行升主动脉根部层面噪声标准差(SD)的测量。评价每组间图像质量、SD及ED的差异。结果图像质量评分4分以上占90.25%(426/472)。3组图像质量评分、SD及ED分别为(4.71±0.65)分、(4.60±0.78)分、(4.62±0.80)分;(26.13±6.59)HU、(30.25±7.15)HU、(33.94±7.44)HU;(4.80±2.67)mSv、(4.70±3.04)mSv、(4.20±2.81)mSv。3组间比较SD差异有统计学意义(P=0.000),图像质量评分及ED差异无统计学意义(P>0.05)。结论 320排CT在25 kg/m2<BMI≤30 kg/m2时采用100 kV行CTCA,图像质量能够满足临床诊断需求。使用70%～80%R-R时间窗曝光,可进一步有效减少ED。

Pixel and Column Fixed Pattern Noise Suppression Mechanism in CMOS Image Sensor

A double sampling circuit to eliminating fixed pattern noise(FPN) in CMOS image sensor (CIS) is presented. Double sampling is implemented by column switch capacitor amplifier directly, and offset compensation is added to the amplifier to suppress column FPN. The amplifier is embedded in a 64×64 CIS and successfully fabricated with chartered 0.35 μm process. Theory analysis and circuit simulation indicate that FPN can be suppressed from millivolt to microvolt. Test results show that FPN is smaller than one least-significant bit of 8 bit ADC. FPN is reduced to an acceptable level with double sampling technique implemented with switch capacitor amplifier.

A speech enhancement algorithm to reduce noise and compensate for partial masking effect

To enhance the speech quality that is degraded by environmental noise,an algorithm was proposed to reduce the noise and reinforce the speech.The minima controlled recursive averaging(MCRA) algorithm was used to estimate the noise spectrum and the partial masking effect which is one of the psychoacoustic properties was introduced to reinforce speech.The performance evaluation was performed by comparing the PESQ(perceptual evaluation of speech quality) and segSNR(segmental signal to noise ratio) by the proposed algorithm with the conventional algorithm.As a result,average PESQ by the proposed algorithm was higher than the average PESQ by the conventional noise reduction algorithm and segSNR was higher as much as 3.2 dB in average than that of the noise reduction algorithm.

A continuous differentiable wavelet threshold function for speech enhancement

Enhanced speech based on the traditional wavelet threshold function had auditory oscillation distortion and the low signal-to-noise ratio (SNR). In order to solve these problems, a new continuous differentiable threshold function for speech enhancement was presented. Firstly, the function adopted narrow threshold areas, preserved the smaller signal speech, and improved the speech quality; secondly, based on the properties of the continuous differentiable and non-fixed deviation, each area function was attained gradually by using the method of mathematical derivation. It ensured that enhanced speech was continuous and smooth; it removed the auditory oscillation distortion; finally, combined with the Bark wavelet packets, it further improved human auditory perception. Experimental results show that the segmental SNR and PESQ (perceptual evaluation of speech quality) of the enhanced speech using this method increase effectively, compared with the existing speech enhancement algorithms based on wavelet threshold.

Property of Quantum Correlations with Correlated Noise

We analyze the classical and quantum correlation properties of the standard and so-called quasiclassical depolarizing channel with correlated noise and non-Markovian dephasing channel, specifically we use the quantum discord, entanglement, and measurement-induced disturbance （MID） to measure the quantum correlations. For the depolarizing channel, we find that the memory effect has more influence on the MID and quantum discord than entanglement. For the dephasing channel, we show that the non-Markovian dephasing channel is more robust than Markovian dephasing channel against deeoherence. We also find that at first MID and quantum discord take different values, and then after a specific time they will take almost the same value and both decay monotonically in the same way.

Novel Retinex algorithm by interpolation and adaptive noise suppression

In order to improve image quality, a novel Retinex algorithm for image enhancement was presented. Different from conventional algorithms, it was based on certain defined points containing the illumination information in the intensity image to estimate the illumination. After locating the points, the whole illumination image was computed by an interpolation technique. When attempting to recover the reflectance image, an adaptive method which can be considered as an optimization problem was employed to suppress noise in dark environments and keep details in other areas. For color images, it was taken in the band of each channel separately. Experimental results demonstrate that the proposed algorithm is superior to the traditional Retinex algorithms in image entropy.

Compressor Map Prediction by Neural Networks

This paper presents a study where artificial neural networks are used as a curve fitting method applying measured data from an axial compressor test rig to predict the compressor map. Emphasis is on models for prediction of pressure ratio, compressor mass flow and mechanical efficiency. Except for evaluation of interpolation and extrapolation capabilities, this study also investigates the effect of the design parameters such as number of neurons and size of training data. To reduce the effect of noise, the auto associative neural network has been applied for noise filtering of the data from the parameters used to calculate the efficiency. In summary, the results show that artificial neural network can be used for compressor map prediction, but it should be emphasized that the selection of data normalisation scale is crucial for the model where compressor mass flow is predicted. Furthermore, it is shown that the AANN （auto associative neural network） can be used to the reduce noise in measured data and thereby enhance the quality of the data.

具有涨落质量的线性谐振子的共振行为

Brown运动中,环境分子的吸附能力使Brown粒子的质量存在涨落.本文将这一质量涨落建模为对称双态噪声,以考察其对系统共振行为的影响.首先,利用Shapiro-Loginov公式和Laplace变换推导系统稳态响应振幅的解析表达式,并根据相应数值结果,研究系统的共振行为;然后,通过仿真实验对理论与实际的符合情况进行对比分析,验证理论结果的可靠性及其对实际应用的指导意义.理论结果和仿真实验均表明:1)系统稳态响应为频率与外部驱动相同的简谐振动;2)稳态响应振幅随外部驱动频率、振子质量、噪声强度及相关率的变化分别相应出现真实共振、参数诱导共振、随机共振现象;3)质量涨落噪声导致系统共振形式出现多样化现象,包括单峰共振、单峰单谷共振、双峰共振等.