基于周期势系统随机共振的轴承故障诊断

提出基于普通变尺度和周期势自适应随机共振理论,检测噪声背景下轴承滚动体的故障特征.在具体实施过程中,首先用普通变尺度的方法满足随机共振中小参数的条件,然后用随机权重粒子群优化算法作为自适应随机共振参数寻优的优化算法,同时用改进的信噪比作为评价指标.噪声背景下含轴承滚动体故障的实验信号经过普通变尺度下的自适应随机共振处理和优化后,微弱的故障特征可以有效的提取出来.将普通变尺度下的双稳态自适应随机共振和周期势自适应随机共振进行了对比,结果表明周期势自适应随机共振比双稳态自适应随机共振能进一步提高信噪比,并且比双稳态自适应随机共振迭代次数少,用时短.这说明提出的基于普通变尺度和周期势系统自适应随机共振的轴承滚动体故障诊断方法具有优越性,尤其是在工程实际中,故障监测所需的数据量大,计算时间长,如能较早的预警,可以提高诊断效率并减少不必要的损失.因此,这种轴承滚动体故障诊断方法对提高机械设备故障诊断效率具有参考价值.     

等效岩体三维随机节理网络模型构建及其在两河口水电站中的应用

节理的存在对水电高陡岩质边坡的力学性质有重要影响,如何构建反映三维节理分布特征的等效岩体计算模型,是分析与评价岩体力学特性的关键。本文基于损伤力学和统计强度理论,在三维岩石破裂过程分析（RFPA3D）软件的基础上,提出了一种计算等效岩体三维随机节理网络模型的新方法。首先,基于Baecher模型和Monte-Carlo方法,在RFPA3D软件中实现了三维随机离散节理网络（Discrete fracture network,DFN）模型的重构。然后,利用RFPA3D软件内嵌DFN模型,赋予节理和岩石不同的力学参数,构建了工程尺度等效岩体三维随机节理网络模型,实现了三维随机节理岩体破裂过程、变形和强度等力学性质的分析。最后,以两河口水电站左岸边坡坝址区下游节理岩体为研究对象,验证了三维随机DFN模型的准确性,开展了研究区内节理岩体尺寸效应研究,并获得了研究区内岩体的表征单元体（Representative elementary volume,REV）和等效力学参数。该研究成果为等效岩体力学行为分析提供一种新方法。      

二阶线性非散度型抛物方程解的局部正则性估计

发展了Acerbi等的方法,得到了一类具有小BMO系数的二阶线性非散度型抛物方程解的二阶偏导数在Orlicz空间中的局部正则性估计.这种正则性估计可以应用于W2P,1解的存在性问题.     

Linear Stochastic Dynamical System under Uncertain Load: Inverse Reliability Analysis

The reliability of a linear dynamical system driven by a partially known Gaussian load process, specified only through its total average energy, is studied. A simple dynamic parallel and series system reliability network is investigated for the failure analysis using the crossing theory of stochastic processes. The critical input power spectral density of the load process which maximizes the mean crossing rate of a parallel or series system network emerges to be fairly narrow banded and hence fails to represent the erratic nature of the random input realistically. Consequently, a tradeoff curve between the maximum mean crossing rate of the reliability network and the disorder in the input, quantitatively measured through its entropy rate, is generated. Mathematically, the generation of the tradeoff curve of nondominated solutions, known as the Pareto optimal set, leads to a nonlinear, nonconvex, and multicriteria optimization problem with conflicting objectives. A recently developed Pareto optimization technique, implemented through genetic algorithm, has been successfully exploited to solve the optimization problem. A suitable exploitation of stochastic process theory circumvents the task of handling an apparent robust optimization problem (i.e., optimization under uncertainty) and at the same time, reduces the dimensionality of the multiobjective optimization scheme in view of both the multiobjectivity and constraints in the aforementioned methodology. The optimally disordered inputs which simulate the worst performance of the system of a spring-supported coupled rod assembly, has been studied as a numerical illustration of the mathematical formulation.     

铝电解净化系统中的噪声危害及其控制

本文对工业噪声的危害进行了分析论述,并分析论述了铝电解烟气净化系统中噪声的来源与种类,提出了相应的治理和控制意见,对铝电解烟气净化系统的设计、运行管理具有一定的指导意义。     

Dynamic Coupling Effects in Frictional Geomaterials—Stochastic Resonance

Nonlinear, dynamic coupling effects and the manifestation of stochastic resonance are explored in the context of frictional geomaterials. The first experiment is designed to study a single interface between two mineral surfaces. Results demonstrate that as the amplitude of the driving signal approaches the threshold of static frictional resistance, the noise level required to cause slippage decreases and the peak output signal-to-noise ratio increases, inducing stochastic resonance. The second experimental study is conducted with sand specimens. While the classical signature of stochastic resonance is not observed in these multiinterface systems, nonlinear energy coupling effects appear. The effect of signal interaction through the nonlinear behavior of the medium is further studied by simultaneously exciting the specimen with two sinusoidal signals of different frequencies. The output response at the frequency of the primary driving signal increases as the amplitude of the secondary “noise” signal increases. Coupling increases as the driving signal brings the specimen to its nonlinear regime. The results highlight the interaction between friction and vibration in geomaterials, and suggest potential implications to experimental studies, construction operations, and dynamic phenomena such as seismic response and landslides.     

Stochastic Response of an Inclined Shallow Cable with Linear Viscous Dampers under Stochastic Excitation

Considering the coupling between the in-plane and out-of-plane vibration, the stochastic response of an inclined shallow cable with linear viscous dampers subjected to Gaussian white noise excitation is investigated in this paper. Selecting the static deflection shape due to a concentrated force at the dampers location and the first sine term as shape functions, a reduced four-degree-of-freedom system of nonlinear stochastic ordinary differential equations are derived to describe dynamic response of the cable. Since only polynomial-type terms are contained, the fourth-order cumulant-neglect closure together with the C-type Gram-Charlier expansion with a fourth-order closure are applied to obtain statistical moments, power spectral density and probabilistic density function of the cable response, whose availability is verified by Monte Carlo method. Taking a typical cable as an example, the influence of several factors, which include excitation level and direction as well as damper size, on the dynamic response of the cable is extensively investigated. It is found that the sum of mean square in-plane and out-of-plane displacement is primarily independent of the load direction when the excitation level and viscous coefficient of the damper are fixed. Moreover, the peak frequency and half-band width of the spectra of both the in-plane and the out-of-plane displacements are increasing with excitation level when the damper size is constant. It is also observed that, even though the actual optimal damper size is slightly greater than the one obtained by the complex modal theory, the difference of statistical moment of the cable caused by these two damper size is negligible, so the vibration reduction effect provided by the theoretical optimal viscous coefficient is satisfactory.     

一种RSA公钥体制的数学模型及应用

通过具体案例说明RSA公钥体制的算法过程及RSA体制在加密和数字签名中的应用.     

燃气混合工艺系统分析及在泰钢的应用

介绍了燃气稳压定比、燃气加压定比及燃气热值检测和反馈混合系统的组成及工艺流程。泰钢30万t冷轧薄板项目采用燃气稳压定比煤气混合系统,由于气源压力波动范围大、煤气用量小,系统不能正常运行;60万t冷轧项目采用热值检测和反馈混合系统,该系统运行良好。同时提出了燃气混合系统的改进建议,即采用燃气双级稳压定比混合系统、双混合管路加压定比混合系统。     

降低液压系统噪音的探讨

分析了液压系统振动与噪声的声源,介绍了液压系统振动与噪音的测定。在简述机械噪音、流体噪音的控制方法后,论述了降低液压泵及液压系统噪音的措施。     

变电站综合自动化系统及应用

阐述了变电站综合自动化系统结构和功能,通过具体实例,介绍了一种基于微机保护装置的分层分布式变电站综合自动化系统在变电站中的应用,并探讨了变电站综合自动化的发展方向。     

智能控制系统发展综述及其应用

智能控制是当今控制学领域研究和发展的热点之一。本文论述了智能控制的一般概念,探讨了智能控制在铜电解联动机组的应用。