等效连续A声级检测结果不确定度评定

本文通过对等效连续A声级Leq测量中五个不确定度分量的评定,得出了噪声测量结果的不确定度评定报告。     

功能区噪声测量值的代表性分析

功能区噪声的变化是没有规律的,在日常的功能区噪声监测中,通常将每季度最后一个月月初的一昼夜的监测结果,作为该季度的功能区噪声值。为了检验此方法的代表性,作者选择了六天分别在四个功能区进行24小时噪声监测。通过对六天监测结果的统计分析和六日平均值的置信区间的计算分析,以及对一日测量值的可信限分析,总结出各类区一日测量值的可信限,证明了用一日测量值来代表功能区的季度噪声值具有较好的代表性。     

基于OTPA方法的直升机舱内噪声分析

论述了运行工况传递路径分析(OTPA)方法的基本原理。建立了直升机的OTPA分析模型,并进行了实际运行工况下的测量。使用估计的传递函数计算了噪声合成值,与实测运行工况值对比验证了传递函数的准确性。分析量化了各噪声源对直升机舱内噪声的贡献量,表明对直升机舱内噪声影响更大的成分是结构噪声,源自主减速器和发动机。分析结果为该型直升机的噪声控制提供了有效的依据。     

基于双因素模型的股票市场噪声交易风险测度

在传统资产定价理论的基础上,通过数理推导的方式将影响资产定价的公司横截面因素与资本市场因素结合形成双因素模型,用其贝塔值代替传统CAPM模型的贝塔值测度噪声交易风险,用改造的噪声交易量指数NTVI测度噪声交易风险中的行为贝塔值。通过沪深两市A股的股票进行实证检验,结果表明我国股票市场存在噪声交易风险,双因素CAPM模型测量的噪声交易风险与收益的可决系数大于传统CAPM模型测量的噪声交易风险与收益的可决系数,显示双因素CAPM模型对噪声交易风险的测度优于传统CAPM模型。     

公园环境噪声及游人主观反应

1990年6月至1991年1月,作者对杭州市柳浪闻莺公园和植物园的环境噪声进行了测量,得到各测点的L_N和L_(eq)值。在测量的同时,对游人进行了环境噪声主观调查。本文就公园的环境噪声及游人对噪声的主观反应进行分析和讨论。     

水平阵测量水中目标辐射噪声的阵倾斜校准研究

水平直线阵测量水中目标辐射噪声已被广泛使用.在合作目标情况下,当直线阵倾斜时,直接测量的目标方位角与真实值之间有一个偏差.本文对这一偏差产生的波束形成器性能下降情况进行了仿真,并给出了目标方位角的补偿方法.     

基于DSP与PTR2000的智能路灯节电系统设计与研究

针对道路照明设备的特殊要求,结合PTR2000无线通信技术,提出一种根据照度和噪声测量值,运用模糊控制算法优化路灯系统的节能措施,并对系统进行软硬件设计。     

长春师范学院环境噪声调查与分析

对长春师范学院校园环境噪声进行了实地调查和测量,通过测量数据的处理与分析,了解了该区域环境噪声的时空分布特征,并对其声环境质量做出了客观的评价。     

强噪声背景下微弱信号检测装置的一种可行性方案的研究

在测量微弱信号被掩盖在强噪声中的信号时,锁相放大器(Lock-in Amplifier,LIA)表现出了良好的性能.但是由于其本生存在中心频率不稳定、带宽不能太窄及对信号缺乏跟踪能力等缺点,造成对测量微弱信号的限制.对锁相放大器进行一些分析的基础上,设计出一个双相位锁相放大器(Dual Phrase Lock-in Amplifier),并用Pspice/OrCAD进行了实验性的论证.结果表明该放大器可以实现微伏(μV)级别的信号识别,噪声信号的均方根值约为1mV,幅值识别准确率在0.5％以内.     

ARJ-700飞机噪声适航试飞中差分GPS的应用

在ARJ-700飞机的噪声适航试飞中,需要使用飞机自身系统以外的测试系统来测量飞机的航迹,用于噪声数据的修正和飞行有效性判断,经过对几种常见的航迹测量方法的对比分析,选取并搭建了具有精度高、操作使用便捷的特点的差分GPS(DGPS)航迹测量系统,进行了精度验证试验,并在试飞中成功应用。     

The time-delay digital tanlock loop: performance analysis in additive Gaussian noise

Recently, a new non-uniform sampling digital phase-locked loop, the time-delay digital tanlock loop (TDTL), has been proposed. We have analyzed in a previous work the first- and second-order TDTLs under noise-free conditions. In this work, we analyze the performance of the TDTL in the presence of additive Gaussian noise for different values of the loop parameters. It is shown that the expected value of the steady-state phase errors at the input and the output of the phase error detector are equal to the noise-free steady-state values, while the variance is significantly reduced when the signal-to-noise ratio is increased or the phase shift introduced by the time-delay approaches 90°. The locking ranges of the TDTL parameters under noise-free conditions are unchanged by the presence of noise.     

A robust super-resolution method with improved high-frequency components estimation and aliasing correction capabilities

In this paper, we have proposed a robust super-resolution high-frequency component estimation (RS-HFCE) method, which can efficiently estimate lost high-frequency components and correct aliasing effects of low-frequency components of an image. The fundamental principle of operation of the proposed method is based on the idea that, when a baseband band-limited image signal of known bandwidth in a high-resolution lattice is iteratively low-pass filtered in the frequency domain, the unknown values in the lattice can be interpolated, thus correcting the aliasing for the low-frequency components. If this process is done along with adjusting the amplitudes of the known pixel values, some high-frequency components of an image are automatically extrapolated. In order to provide simultaneous edge preservation and noise removal capabilities of the super-resolved images, an improved version of an adaptive Perona–Malik (PM) model is incorporated into the process. One of the characteristics of the proposed method is its high level of tolerance capabilities to reconstruction errors and noise caused by an increase in the reconstruction scaling factors. High quality images of higher resolution are still appreciably reconstructed when greater magnification factors are used. From a couple of experiments on real images, and using both subjective and objective image quality assessment measures, it is demonstrated that the proposed method outperforms most of other classical methods.     

基于改进的Canny算子图像信息提取算法研究

研究文本定位与特征提取问题。针对传统的Canny算子图像检测算法的不足,提出了一种改进的Canny算子图像信息特征提取算法。研究方法是:首先对彩色图像进行高斯金字塔分解,然后用Canny算子检测彩色图像,提取边缘图像,再经过通二值化,去噪方差投影定位文本区域。实验结果表明,本文提出的方法有效、实用。     

蓝细菌体系中外噪音维持的生物钟

采用数值模拟方法 ,研究了外部色噪音对蓝细菌生物钟体系的影响。结果表明,外噪音可以在体系的确定性稳态区诱导产生振荡和相干共振;在确定性振荡区,外噪音对振荡起到了破坏性作用,但是振荡的周期并没有随着外噪音的增加而明显变化,说明体系对外噪音具有鲁棒性;而在右侧分叉点附近的确定性振荡区,也发现了外噪音诱导相干共振现象。另外,研究了噪音相关时间的影响,发现其与噪音强度起相反的作用。     

潜艇主要噪声源分离技术综述

潜艇主要噪声源的分离技术对于指导潜艇降噪措施的正确实施和辅助水下噪声系统的声学设计和噪声预报有着重要意义;本文从潜艇主要噪声源产生机理及其传播途径入手,讨论潜艇噪声源识别研究的特点;然后在综合分析国内外相关研究成果的基础上,给出一些潜艇主要噪声源分离技术前瞻。     

控制交通噪声声屏障的发展历程及发展趋势

随着交通运输业的发展,交通噪声污染越来越严重。研究经验表明,声屏障作为一种降噪设施,能有效地控制交通噪声。文中介绍了声屏障的降噪机理和发展历程,并综述了声屏障的研究现状和发展趋势。     

内燃机噪声测试系统设计

内燃机的开发利用给我们带来巨大便利的同时,也给我们带来烦躁的噪音,文章通过分析内燃机噪声产生原因,提出降噪措施,并通过采用朗德DATaRec 4 DIC24模块采集系统,开发出一套先进的多通道内燃机噪声测试系统,为内燃机降噪提供准确数据。     

Some Properties of the Log-Likelihood Ratio

The detection of a deterministic signal in additive noise is considered. The log-likelihood ratio is studied for three cases: stationary white noise process, stationary Markov noise process, and noise process with independent increments. Procedures leading to realizable optimum detection schemes and related examples are given. An approximation to the log-likelihood ratio, which leads to the locally optimum detector, is also presented for the white noise case.     

柴油发电机组噪声控制研究

柴油发电机组噪声强,发热量大。针对此,采用隔声、吸声、消声、通风散热等具体措施。实践证明：方案设计合理,达到了预期的降噪效果,符合工业企业噪声排放标准。     

Dynamic stochastic resonance-based grayscale logo extraction in hybrid SVD-DCT domain

This paper presents a novel dynamic stochastic resonance (DSR)-based technique for robust extraction of a grayscale logo from a tampered watermarked image. The watermark embedding is done on the singular values (SV) of the discrete cosine transform (DCT) coefficients of the cover image. DSR is then strategically applied during the logo extraction process where the SV of DCT coefficients are tuned following a double-well potential model by utilizing the noise introduced during attacks. The resilience of this technique has been tested in the presence of various noises, geometrical distortions, enhancement, compression, filtering and watermarking attacks. The proposed DSR-based technique for logo extraction gives noteworthy robustness without any significant trade-off in perceptual transparency of the watermarked image. A maximization approach has been adopted for the selection of bistable double-well parameters to establish noise-enhanced resonance. When compared with existing watermark extraction techniques based in SVD, DCT, SVD-DCT domains, as well as with their combination with DSR, the results suggest that remarkable improvement of robustness is achieved by using DSR on singular values of DCT.