对称消声器传递损失测量及误差修正

为了提高对称消声器传递损失的测量效率，基于声学理论分析，提出了一种单负载法传递损失计算模型。针对反射系数较大的吸声末端，导致该方法在实际测量中存在较大误差的问题，推导出了一种能够消除测试管道末端反射声波在上、下游形成多次反射的修正公式。通过自制阻抗管进行试验测试，结果表明：在末端声学负载吸声性能良好的情况下，单负载法传递损失计算模型能够精确计算出对称消声器的传递损失；修正公式能够有效地消除末端负载所引起的反射波对传递损失计算的影响，降低对末端声学负载吸声性能的要求，保证单负载传递损失计算模型的适用性。     

测井曲线标准化方法研究

由于长岭凹陷区经过近60年的勘探开发,再加上井场井眼条件的差异、测井系列、仪器刻度、测量时间及操作者不同等因素,使得各测井曲线存在系统误差。因此在开展储层参数研究和有效厚度划分时,为消除这些非地层因素对原始资料的影响,有必要对测井曲线进行标准化,以保证解释结果的合理性与可靠性。测井曲线标准化方法可以分为定性和定量两种类型。其中定性方法主要包括直方图法标准化校正、均值法标准化校正和重叠图法标准化校正;定量方法则为趋势面分析校正法。本论文利用Matlab软件,采用趋势面方法对研究区域内的井进行测井曲线标准化。结果表明经过趋势面法标准化校正能够消除不利因素,准确的提取出测井曲线中的各种有用地质信息。     

一种新的风电场复杂下垫面场地校准模型

针对现有方法模型简单、气象因素考虑不足和缺少异常数据检测等问题,提出一种基于相对密度离群因子（relative RDOF）异常检测和支持向量回归（SVR）组合的场地校准模型。首先,通过RDOF与四分位法对测风塔与风电机组距下垫面相同高度风速间的风速比进行异常数据检测,间接实现风速预处理;同时,根据测风塔与风电机组相同高度风切变序列的相关性,动态引入大气稳定度等级,与多种常规自然因素共同作为模型输入。然后,建立SVR场地校准模型修正风速。最后,通过算例验证,并与国际电工委员会（IEC）标准方法进行对比。结果表明,该方法可有效提升场地校准模型的风速修正精度。     

Influence of physical and biological variability and solution methods in fruit and vegetable quality nondestructive inspection by using imaging and near-infrared spectroscopy techniques: A review

Over the past decades, imaging and spectroscopy techniques have been rapidly developing and widely applied in nondestructive fruit and vegetable quality assessment. The physical properties (including size, shape, color, position, and temperature) and biological properties (including cultivar, season, maturity level and geographical origin) of fruits and vegetables vary from one to another. A great variety of physical and biological properties of agricultural products influence the optical propagation properties and interaction behaviors with incident light, thus decreasing the quality inspection accuracy. Many attempts have been made in image correction and spectral compensation methods to improve the inspection accuracy. This paper gives a detailed summary about influence of physical and biological variability, as well as the correction and compensation methods for eliminating or reducing the effects in fruit and vegetable quality nondestructive inspection by using imaging and spectroscopy techniques. The advantages and disadvantages of the solution methods are discussed and summarized. Additionally, the future challenges and potential trends are also reported.     

An efficient nonlinear polynomial color characterization method based on interrelations of color spaces

A well-known color characterization method is to take an image of a color chart and then to find the mapping matrix from the digital RGBs to the corresponding known CIEXYZs. However, the prediction errors are generally large in CIELAB color space because of the nonlinear transformation from CIEXYZs to CIELABs. In this article, we propose an efficient and simple nonlinear method for the color characterization of input devices. The approach for deriving a colorimetric mapping between digital RGB signals and CIELAB tristimulus values uses the polynomial modeling by considering the interrelations among the standard CIE color spaces. Furthermore, to improve the accuracy of solution, we take the polynomial root terms extension. Our algorithm is simple to implement because only a least-squares mapping should be solved. Various computational results are given to demonstrate the efficiency and capability of the proposed method.     

输气管道仿真模型校正技术研究进展

为了解决输气管道仿真系统存在计算值与实际值偏差的问题,对解决该问题的模型校正技术展开国内外调研。提出造成仿真计算不精准的三个主要误差来源:输入参数测量误差、缓变参数误差、手工输入误差。最后通过分析国内外仿真模型校正技术研究现状,建议在动态仿真的基础开展输气管道的模型校正技术研究,以避免输气管道系统数据波动带来的误差。     

Analysis and improvement of the influence of sample shape on Pu measurement results

ABSTRACT

The analysis method of Fast Neutron Multiplicity Counting (FNMC) plays an increasingly important role in the measurement of nuclear material properties. Based on the assumption of point model, fast neutron multiplicity measurement equation is derived which can be used to measure the mass of Pu sample. However, the deviation of the simulated measurement of 1 kg Pu sample reaches 16.6% and increases with mass. Because nonpoint source samples of different shapes do not fully satify the hypothesis. To correct this deviation, a set of fast neutron multiplicity counters was built by Geant4 to simulate and study the mass attribute of Pu samples.The cylindrical sources of different shapes and different masses were simulated, the self-multiplication factor and α coefficient were corrected.And the corresponding third-order polynomial fitting equation was obtained, the goodness of fit was greater than 0.970. In the same way, the spherical and spherical shell source samples in the mass range of 0–5 kg were analyzed, the corrected mass deviation of samples was less than 10% in this interval. The results show that the combination of the fast neutron multiplicity counter and parameter correction can accurately measure the sample mass attribute.     

钛合金TA16弹塑性修正因子数值分析方法研究

本文对核级规范提供的奥氏体不锈钢材料的弹塑性修正因子（KE）的各种敏感因素进行数值验算，确定了不锈钢材料Z2CND18.12(控氮)简化弹塑性疲劳分析所需KE与规范限值之间最小保守裕量为12%。基于钛合金TA16的单轴拉伸、应变循环和应力循环试验，确立了TA16在30 ℃和350 ℃的Chaboche本构模型参数。基于TA16的本构模型参数，对TA16开展各种敏感因素下的弹塑性分析，并参考奥氏体不锈钢的KE表达式和Z2CND18.12(控氮)的KE最小保守裕量迭代计算出TA16的相关系数。TA16的相关系数A、B、C、m、n分别为1.37、1.26、1.37、2.0和0.25。     

Modified transform-based gamma correction for MRI tumor image denoising and segmentation by optimized histon-based elephant herding algorithm

Medical image processing is typically performed to diagnose a patient's brain tumor prior to surgery. In this study, a technique in denoising and segmentation was developed to improve medical image processing. The proposed approach employs multiple modules. In the first module, the noisy brain tumor image is transformed into multiple low- and high-pass tetrolet coefficients. In the second module, multiple low-pass tetrolet coefficients are applied through a modified transform-based gamma correction method. Generalized cross-validation is used on multiple high-pass tetrolet coefficients to obtain the best threshold value. In the third module, all enhanced coefficients are applied to the partial differential equation method. In the final module, the denoised image is applied to Atanassov's intuitionistic fuzzy set histon-based fuzzy clustering method with centroid optimization using an elephant herding method. Accordingly, the tumor part is segmented from the nontumor part in the magnetic resonance imaging brain images. The method was assessed in terms of peak signal-to-noise ratio, mean square error, specificity, sensitivity, and accuracy. The experimental results showed that the suggested method is superior to traditional methods.     

基于KJADE的列车轴承轨边声学诊断方法研究

为在线诊断运行列车的轴承状态,提出一种基于核特征矩阵联合近似对角化(kernel joint approximate diagonalization of eigen-matrices,简称KJADE)的列车轴承轨边声学故障诊断方法。首先,从校正后的轨边信号中提取原始特征,将其通过非线性映射函数映射到高维特征空间;其次,对特征空间的核矩阵进行四阶累积量的特征分解,获得新融合特征,并采用支持向量机分类器对融合特征进行辨识;最后,对轴承外圈、内圈、滚子故障和正常4种状态下的列车轨边声学信号进行分析。结果表明,该方法可以有效实现对列车轴承轨边声音信号的非线性特征提取,提高了故障的识别率。