图象中的噪声及复原方法研究

阐述了噪声图象的复原方法。介绍了图象中噪声的产生及与图象信号相关的噪声的分类，讨论了用于图象复原的均值滤波、中值滤波、自适应雏纳滤波、形态学滤波和小波去噪的工作原理和适用性。为进一步提高图象质量，提出采用融合技术，通过选择合适的算法进行数据融合以发挥不同滤波器的优势。     

轴流局扇的噪声分析及玻璃钢消声器的研制

分析了轴流式局部通风机气动声源特性，从消声器的设计要求出发，研制一种玻璃钢材料制作的双层微穿孔板消声器，经试验结果表明，具有良好的消声性能，而且对局扇的气动特性的影响也小。     

Nonlinear transient response analysis for double walls with a porous material supported by nonlinear springs using FEM and MSKE method

In this paper, we newly propose a fast computation method for the nonlinear transient responses including coupling between nonlinear springs and sound proof structures having porous materials using FEM. In this method, we extend our numerical method named as Modal Strain and Kinetic Method (i.e. MSKE method proposed previously by Yamaguchi who is one of the authors) from linear damping analysis to nonlinear dynamic analysis. We assume that the restoring force of the spring has cubic nonlinearity and linear hysteresis damping. To calculate damping properties for soundproof structures including elastic body, viscoelastic body and porous body, displacement vectors as common unknown variable are solved under coupled condition. The damped sound fields in the porous materials are defined by complex effective density and complex bulk modulus. The discrete equations in physical coordinate for this system are transformed into nonlinear ordinary coupled differential equations using normal coordinates corresponding to linear natural modes. Further, using MSKE method, modal damping can be derived approximately under coupled conditions between hysteresis damping of viscoelastic materials, damping of the springs and damping due to flow resistance in porous materials. The modal damping is used for the nonlinear differential equation to compute nonlinear transient responses.Moreover, using the proposed method, we demonstrate new vibration phenomena including nonlinear coupling between nonlinear springs and soundproof structures by use of a simplified model. As a typical numerical example of the soundproof structure, we adopt double walls with a porous material. The double walls are supported by nonlinear concentrated springs. We clarify influences of amplitude of the impact force on nonlinear transient responses. We focused on the vibration modes, which magnify the amplitudes of the double walls. In these modes, the internal air of the porous material played a role of a pneumatic spring. Under a very large impact force as a severe condition, there exist the complicated nonlinear couplings between these modes and the super harmonic components of the rigid modes of the whole structure with large deformations in the nonlinear springs.     

浅谈有线电视双向网改造的规划、设计与调试

随着经济、社会的发展,有线电视的服务功能也在不断地拓展和提高。HFC网络所提供的全业务网是一种新型、成熟的宽带业务网,对有线电视运营商具有极大吸引力。本文以福州广电网络建设为例着重介绍网络双向改造设计、施工、调试的思路和方法。     

Assessment Of Noise Impacts At Airports

Airport operation is a major source of community concerns due to aircraft noise emissions particularly in locations close to airports and aircraft flight tracks. The effects of aircraft noise on humans can cause hearing damage for people working at airports and speech and sleep interference which can develop into stress for nearby communities. As such, it becomes essential when locating and designing to expand airports to optimize flight paths in a way to reduce noise exposure to nearby communities. For this purpose, it is required to assess changes in noise levels resulting from new runway configurations, evaluate increased aircraft operation demand, new fleet mix, revised routings and airspace structures, alternative flight profiles, and modifications to other operational procedures. This paper presents a noise impact assessment for the proposed expansion at the Beirut International Airport, Lebanon. Field noise measurements were collected at sensitive noise receptors along selected locations around the airport and the corresponding airport traffic flow was characterized. A mathematical model was then applied to simulate noise levels as a function of the different airplane classes, operations, flight path, and landing characteristics. The model was also used to predict future noise levels, optimize airplane flight path, and assess mitigation measures to minimize potential aircraft noise impacts.     

浅议高速电梯中的减振减噪设计

针对高速电梯引起的振动及噪声,对其源头与传播途径进行分析。通过在曳引机、轿厢、轿架、返绳轮以及导轨等方面采取的减振减噪措施,实现了减少振动及噪声,提高电梯舒适性的效果。     

Damping identification with the Morlet-wave

In the past decade damping-identification methods based on the continuous wavelet transform (CWT) have been shown to be some of the best methods for analyzing the damping of multi-degree-of-freedom systems. The CWT methods have proven themselves to be resistant to noise and able to identify damping at closely spaced natural frequencies. However, with the CWT-based techniques, the CWT needs to be obtained on a two-dimensional, time-frequency grid, and they are, therefore, computationally demanding. Furthermore, the CWT is susceptible to the edge effect, which causes a non-valid identification at the start and the end of the time-series.This study introduces a new method, called the Morlet-wave method, where a finite integral similar to the CWT is used for the identification of the viscous damping. Instead of obtaining the CWT on a two-dimensional grid, the finite integral needs to be calculated at one time-frequency point, only. Then using two different integration parameters, the damping ratio can be identified. A complete mathematical background of the new, Morlet-wave, damping-identification method is given and this results in a root-finding or a closed-form solution.The presented numerical experiments show that the new method has a similar performance to the CWT-based damping-identification methods, while the method is numerically, significantly less demanding, completely avoids the edge effect, and the procedure is straightforward to use.     

用噪声测量方法分析模拟电路故障的研究

提出了一种用噪声测量及分析理论进行模拟电路诊断的方法，即一种因-果逆向推理方法。与传统的因-果推理方法比较，这种方法无需对故障的类型及是否存在作预先限定，且能对复合性故障进行分析诊断。鉴于模拟电路故障的诊断比器件缺陷的检测难度更大，这里论证了模拟电路输出噪声的计算方法，分析了电路故障情况与正常情况时的差别，讨论了电路故障诊断的方法。最后，利用这种方法对一种有源滤波器的电路故障进行了诊断和分析。     

有源降噪声耳罩的发展现状和前景

阐述了有源消声耳罩的特点、历史和现状;探讨了有源耳罩实现技术及产品应用;分析了有源耳罩工程应用中的存在问题和有源消声耳罩的发展前景。