基于自适应噪声滤波的视频对象分割算法

介绍了基本的视频运动对象分割算法,针对变化区域检测算法中固定阈值滤噪的不足,提出了自适应噪声滤波的方法,同时利用计算机图形学中的扫描线填充思想得到变化区域的具体位置,实现视频对象的分割.实验证明了算法的有效性.     

5×100m3/min空压站排空放散噪声治理

文章阐述了空压机排空放散噪声产生机理及特点,采用迷宫室式消声器治理后,取得了明显效果.     

一种新颖的低电源噪声电荷泵

本文提出一种新颖的低电源噪声电荷泵DC-DC变换器。该电路采用电流模控制方式来调整电荷泵充放电电流,并运用差动运放大信号输入时的电流开关特性,使得电荷泵充放电电流不受输入电源电压影响,在稳定状态下和升压过程中都基本维持恒定,有效地减小了输入电流的变化幅度,达到了减小电源噪声的目的。基于Hynix0.5μmCMOS工艺,利用HSPICE对电荷泵整体电路进行仿真验证。结果显示,在2倍模式下电荷泵输入电流仅变化3mA。     

Identification of a Distribution of Stiffness Reduction in Reinforced Concrete Slab Bridges Subjected to Moving Loads

The method for identifying arbitrary stiffness reduction in damaged reinforced concrete slab bridges under moving loads is proposed and dynamic signals measured at several points are used as response data to reflect the properties of the moving loads sensitivity. In particular, the change in stiffness in each element before and after damage, based on the system identification method, is described and discussed by using a modified bivariate Gaussian distribution function. The proposed method in this work is more feasible than the conventional element-based damage detection method from the computational efficiency because the procedure of finite-element analysis coupled with microgenetic algorithm using six unknown parameters irrespective of the number of elements are considered. The validity of the technique is numerically verified using a set of dynamic data obtained from a simulation of the actual bridge modeled with a three-dimensional solid element. The numerical calculations show that the proposed technique is a feasible and practical method that can prove the exact location of a damaged region as well as inspect the complex distribution of deteriorated stiffness, although there is a modeling error between actual bridge results and numerical model results as well as a measurement error like uncertain noise in the response data.     

Vegetation height estimation from Shuttle Radar Topography Mission and National Elevation Datasets

A study was conducted to determine the feasibility of obtaining estimates of vegetation canopy height from digital elevation data collected during the 2000 Shuttle Radar Topography Mission (SRTM). The SRTM sensor mapped 80% of the Earth's land mass with a C-band Interferometric Synthetic Aperture Radar (InSAR) instrument, producing the most complete digital surface map of Earth. Due to the relatively short wavelength (5.6 cm) of the SRTM instrument, the majority of incoming electromagnetic energy is reflected by scatterers located within the vegetation canopy at heights well above the “bald-Earth” surface. Interferometric SAR theory provides a basis for properly identifying and accounting for the dependence of this scattering phase center height on both instrument and target characteristics, including relative and absolute vertical error and vegetation structural attributes.An investigation to quantify the magnitude of the vertical error component was conducted using SRTM data from two vegetation-free areas in Iowa and North Dakota, revealing absolute errors of −4.0 and −1.1 m, respectively. It was also shown that the relative vertical error due to phase noise can be reduced significantly through sample averaging. The relative error range for the Iowa site was reduced from 13 to 4 m and for the North Dakota site from 7 to 3 m after averaging of 50 samples. Following error reduction, it was demonstrated that the SRTM elevation data can be successfully correlated via linear regression models with ground-measured canopy heights acquired during the general mission timeframe from test sites located in Georgia and California. Prior to outlier removal and phase noise reduction, initial adjusted r² values for the Georgia and California sites were 0.15 and 0.20, respectively. Following outlier analysis and averaging of at least 20 SRTM pixels per observation, adjusted r² values for the Georgia and California sites improved to 0.79 (rmse=1.1 m) and 0.75 (rmse=4.5 m), respectively. An independent validation of a novel bin-based modeling strategy designed for reducing phase noise in sample plot data confirmed both the robustness of the California model (adjusted r²=0.74) as well as the capacity of the binning strategy to produce stable models suitable for inversion (validated rmse=4.1 m). The results suggest that a minimum mapping unit of approximately 1.8 ha is appropriate for SRTM-based vegetation canopy height mapping.     

Self-tuning decoupled information fusion Wiener state component filters and their convergence

For the multisensor systems with unknown noise variances, using the modern time series analysis method, based on on-line identification of the moving average (MA) innovation models, and based on the solution of the matrix equations for correlation function, the on-line estimators of the noise variances are obtained, and under linear minimum variance optimal information fusion criterion weighted by scalars for state components, a class of self-tuning decoupled fusion Wiener filters is presented. It realizes the self-tuning decoupled local Wiener filters and self-tuning decoupled fused Wiener filters for the state components. A new concept of convergence in a realization is presented, which is weaker than the convergence with probability one. The dynamic error system analysis (DESA) method is presented, by which the problem of convergence in a realization for self-tuning fusers is transformed into the stability problems of non-homogeneous difference equations, and the decision criterions of the stability are also presented. It is strictly proved that if the parameter estimation of the MA innovation models is consistent and if the measurement process is bounded in a realization or with probability one, then the self-tuning fusers will converge to the optimal fusers in a realization or with probability one, so that they have the asymptotic optimality. They can deal with the systems with the non-stationary or Gaussian measurement processes. They can reduce the computational burden, and are suitable for real time applications. A simulation example for a target tracking system with 3-sensor shows their effectiveness.     

二维空码索引调制算法

针对正交空间调制（QSM）提升传输速率时天线的使用数量增加,需要耗费大量资源且实现困难的问题,提出二维空码正交索引调制（SCOIM）。发射端信息比特分别映射为伪随机（PN）码的索引、天线的索引以及调制符号,调制符号的同相部分和正交部分再分别选择激活的PN码进行扩频,并各自通过激活的天线将信号发射出去。分析和仿真结果表明,相同传输速率时,SCOIM比正交空间调制节约至少一半的索引资源且随着传输速率的提升节约效果成倍增加,并且当误码率为10^-4时具备约5 dB的性能优势。     

Hybrid procedure to determine optimal workforce without noise hazard exposure

Hearing loss is a major occupational health problem among industrial workers. Repetitive exposure to loud noise increases the risk of hearing loss. An administrative noise control such as job rotation can help to reduce workers’ daily noise exposures. In a case where noise levels are excessively high, it is often necessary to assign additional workers to the current workforce to alleviate daily noise exposures that individual workers receive. This paper presents four solution algorithms (three approximations and one exact) to determine a minimum number of workers and their work assignments to attend noisy workstations without noise hazard exposure (that is, daily noise exposure does not exceed 90 dBA). Then, a hybrid procedure which utilizes the four algorithms successively is proposed to improve the solution procedure. Based on a computational experiment on 300 test problems, it is found that the hybrid procedure outperforms all four algorithms (when utilized separately) and is able to find an optimal solution for 88% of the test problems.     

Does risk recognition affect workers’ hearing protection utilisation rate?

In industrial environments, it is very likely to find several workers sharing the same workplaces and being exposed to the same noise pressure levels, who have different perceptions of the risks they are exposed to. These different perceptions could lead to different workers’ attitudes and behaviours. The present study was carried out with a sample of 434 industrial workers exposed to noise pressure levels greater than the action level defined in Portuguese legislation (85 dB(A)). The study aims to analyse the role of individual risk recognitions in hearing protection devices’ (HPD) utilisation rates. A questionnaire was developed to assess workers’ risk perception of high-noise exposure and their utilisation of HPD. The multivariate data analysis of the several variables considered revealed that risk recognition in general and self-efficacy in particular, plays a significant role as a predictor of workers’ behaviour with respect to the use of HPD. Furthermore, these results do suggest that risk recognition should be considered as an essential issue in the design and implementation of any Hearing Conservation Program, in particular in what concerns workers’ training.

Relevance to industry

Results obtained do suggest that workers’ risk recognition could have an important impact on noise exposure protective behaviours and these could be used to design and conceive successful industrial Hearing Conservation Programs.     

形状自适应变换在基于对象编码中的应用

形状自适应DCT(SA-DCT)在低码率时编码效果欠佳,且重建图像块效应明显。针对该问题,提出一种基于形状自适应全相位双正交变换(SA-APBT)的编码系统框架,采用APBT取代DCT进行编码。实验结果表明,该方法在低码率时的编码性能优于SA-DCT,且块效应明显减小。