基于通信网络机车分布式系统实时控制的分析与研究

针对基于通信网络的机车控制系统实时性要求及网络传输的可能影响,通过对列车通信网络(TCN)技术特点以及车载分布式控制应用要求的分析,总结了基于网络的实时控制的处理;在分析各个环节的延时成因及影响的基础上,重点对轨道车辆分布式控制系统实时性能进行了分析及研究,得出基于通信网络的实时控制系统必须考虑网络的影响,特别是传输延迟的影响,同时根据应用实践提出了改善基于通信网络的车载分布式控制系统实时性的原理及方法,并进行了测试及验证。     

改性淀粉抑制赤铁矿反浮选石英的作用机理研究

通过矿物浮选试验、动电位测定以及吸附量测试,考察了4种淀粉抑制剂对赤铁矿和石英浮选性能的影响,并探讨了其作用机理。在碱性条件下,改性淀粉抑制剂对赤铁矿抑制效果明显,且以改性玉米淀粉效果最佳,改性磷酸酯淀粉、改性羧甲基淀粉的抑制效果次之,而普通淀粉抑制作用一般。同时4种淀粉抑制剂对主要脉石矿物石英的抑制效果均不明显。pH=10~12.5条件下,改性玉米淀粉因其羟基氧和裸露在赤铁矿表面的铁元素发生了化学键合,因而选择性抑制能力最佳。分子动力学模拟表明,改性玉米淀粉片段与赤铁矿作用更为紧密,验证了改性淀粉能更好地抑制赤铁矿。     

Model based laser-ultrasound determination of hardness gradients of gas-carburized steel

Gas carburizing is a common industrial process utilized for case hardening of low carbon steels. However, there is a lack of non-destructive evaluation systems for the measurement of hardness-depth profiles. We propose a novel measurement method for the determination of hardness-depth profiles of two-step gas carburized steel specimens. The method is based on the measurement of broadband laser excited Rayleigh waves. Rayleigh waves were generated by a pulsed Nd: YAG laser in the thermoelastic regime and measured with a heterodyne Mach-Zehnder interferometer in the near-field. From two measurements with different source to receiver distances the dispersion diagrams were calculated by means of the phase spectral analysis method. In order to simulate the observed dispersive behavior of the Rayleigh waves, first the two-step gas carburizing process was simulated using solutions of the diffusion equation. The resulting continuous hardness profile was then discretized into up to 100 layers. Thereafter the Rayleigh wave dispersion diagram was calculated from the discretized stack of layers using a delta-matrix formulation of the Thomson-Haskell transfer matrix method. In order to obtain best fitting hardness profiles, the simulated dispersion diagrams were fitted to measurements with a curve fitting algorithm. Comparison of the Rayleigh wave inversion method with destructively obtained Vickers hardness profiles shows good quantitative agreement.     

城市地铁安全监测数据分析与处理

城市地铁深基坑开挖引起的变形给周边环境带来不利影响。地铁施工地处城市繁华区域,复杂的施工环境易导致监测数据异常。本文提出采用置信区间检验并判定监测数据异常,通过总结沉降监测数据异常的3种类型,结合工程实际进行成因分析,进而判定监测数据的正确与否。采用小波分析模型对监测数据存在误差或者粗差进行去噪处理,从而客观反馈周边环...     

Stochastic finite element analysis of shells

In the present paper the stochastic formulation of the triangular composite (TRIC) facet shell element is presented using the weighted integral and local average methods. The elastic modulus of the structure is considered to be a two-dimensional homogeneous stochastic field which is represented via the spectral representation method. As a result of the proposed derivation and the special features of the element, the stochastic stiffness matrix is calculated in terms of a minimum number of random variables of the stochastic field giving a cost-effective stochastic matrix. Under the assumption of a pre-specified power spectral density function of the stochastic field, it is possible to compute the response variability of the shell structure. Numerical tests are provided to demonstrate the applicability of the proposed methodologies.     

基于模糊多属性决策模型的边坡支护设计方案优选

从模糊多属性决策基本理论出发, 建立了边坡支护设计方案优选的评价体系; 根据工程评价特点, 采用层次分析法和变异系数法相结合来确定评价指标的权重, 构造出边坡支护设计方案优选的决策与评价模型, 并把该模型用于某公路边坡支护设计方案优选过程中。实例应用表明, 该模型计算简便, 具有较好的通用性和可操作性, 其结果真实有效。     

化学振荡实验数据采集系统的研制

化学振荡技术目前已应用于多个领域。尤其在分析化学中可以用来测定某些金属离子和阻抑剂,灵敏度很高,然而传统的X-Y记录仪记录的结果精度不够,且无法采用数字化方法进行数据分析,所以设计了一种基于AD620的高精度数据采集系统,可以将化学振荡实验与计算机紧密结合,大大提高实验效率和准确性。     

Time series ground subsidence inversion in mining area based on CRInSAR and PSInSAR integration

The subsidence of the mining area was monitored by analyzing the phase of permanent scatters （PS） which maintained high coherence in magnitude of SAR images.A hew method of spatial unwrapping was presented which used the subsidence rates calculated on comer reflector （CR） points as constraints for PS network to perform the spatial unwrapping using the parametric adjustment method.The algorithm achieved the integration of CR data and PSInSAR algorithm.The colliery dense distributed area around Baisha reservoir was chosen as the study area in the experiment.The time series of subsidence from February in 2007 to February in 2010 is successfully inversed by using the periodic function to simulate the linear and nonlinear components of the deformation.The simulation results show that the accuracy can be ± 2.1 mm with the leveling data being used as the external validation data.     

Improvement of image characteristics in high-voltage computed tomography (CT) by applying a compressed-sensing (CS)-based image deblurring scheme

We have established a high-voltage computed tomography (CT) system with a 1–3 MV LINAC x-ray generator for industrial nondestructive testing. However, reconstructed CT images are typically blurred, limiting its image performance, mainly due to the finite focal spot size of the x-ray source, aspects inherent to detector such as the detector pixel size and the detector resolution, and the reconstruction procedure as well. Thus the recovery of the reconstructed CT images from their degraded version is essential for improving the image characteristics. In this work, we investigated the compressed-sensing (CS)-based deconvolution scheme for more accurate image deblurring in CT. We implemented the proposed image deblurring algorithm for CT and performed a systematic simulation and experiment to demonstrate its viability. Our results indicate that the proposed deblurring scheme appears to be effective for the blurring problems in CT and is applicable to improve its present image characteristics.     

Evaluating the grain size in curved components using the ultrasonic attenuation method with diffraction correction

Ultrasonic wave propagation in curved components was simulated based on the Multi-Gaussian beam theory to eliminate the negative influence of the surface curvature and water path on grain size attenuation evaluation. The multi-frequency weighted attenuation evaluation model with diffraction correction was introduced into the measured attenuation spectrum to control the systematic error. The experimental results show that for 6 blocks with different curvatures and the same mean grain size, the relative error was reduced from 15.41% to 4.28% by using the presented method, and the standard deviation of the error was 15.92% of that of the traditional method.