光力学方法在机械设计上的应用

对机械设计方法进行研究,可进一步明确机械设计的发展趋势与发展方向,进而促进我国机械设计的发展,生产出更多性能优良、功能完善的机械设备与产品。如今,随着高新技术的不断发展与快速迭代,机械类产品的设计理念与方法也在不断推陈出新,借助计算机和信息化等新型方法,可提升产品的结构稳定性,在这些新型方法中,光力学法是典型代表。为此,文章从现代机械设计出发,在详细阐述机械运行状态的基础上,针对机械设计中光力学法的具体应用进行了讨论,以期为广大从业者提供参考。     

胶体中动态光散射的微观机制研究

根据Brownian运动的统计特性和经典电磁场理论,详细地计算了胶体中动态光散射的自相关函数,并将所碍的若干结果应用到有外电场存在的情况中,讨论了有外电场和无外电场两种情况下相应的频谱密度的不同之处。指出所得结果可用于实验中并认为它可定量分析多分散系统。     

基于光干涉法的主轴径向跳动和偏转测量系统仿真与分析

为解决机床主轴实时动态实时测量中加入标准件而引入的误差干扰测量结果,同时存在精度与量程之间的相互制约的问题,提出采用双光束干涉法测量车床主轴偏转状态的变化参数,利用主轴外圆面反射光与参考光产生干涉图样进行分析对比并进行跟踪测量。系统包含探测部分、转动部分、俯仰部分和移动部分,分别用以测量车床主轴偏转方位、偏转角和径向位移,并进行测量精度理论分析和软件仿真,同时还设计光路折叠组件,以进一步提高测量精度和测量范围。     

基于线结构光的钢领内表面圆度测量方法

针对钢领内表面圆度在人工接触式测量中存在主观干扰及自动化程度低等问题,提出一种基于线结构光的钢领内表面圆度测量方法。通过构建图像掩模提取钢领内表面线结构光条纹的感兴趣区域,采用基于主成分分析的改进Steger方法,通过计算条纹法线方向的二阶泰勒展开得到亚像素级条纹中心,提升算法效率。由线结构光条中心坐标相机内外参数、光平面方程及旋转轴方程重构钢领内表面三维点云数据,根据圆度评价方法建立基于点云数据的钢领内表面圆度的测量模型。实验结果表明,本文方法所测最大偏差为5.8μm,与文献中投影法所测结果相比更加精确,重复性测量标准差为0.725,且算法运行时间小于40 ms。     

基于介质损耗因数的红小豆含水率测量方法研究

以红小豆为对象,研究测量信号频率(1kHz～1MHz)、含水率(13.8%～21.8%)、容积密度(747～851kg/m3)和温度(5～40℃)对介质损耗因数的影响规律,从理论上分析介质损耗因数的变化原因,建立500kHz条件下红小豆的介质损耗因数、容积密度和温度与含水率的数学模型,并验证模型的正确性。结果表明：在1kHz～1MHz频段内,红小豆的介质损耗因数随测量信号频率的增大而减小,却随含水率、容积密度和温度的增大而增大;可用三元二次方程表征含水率与介质损耗因数、容积密度和温度之间的关系,模型的决定系数为0.9882。     

基于温度反馈的旋转容积灌装机精度研究

通过对旋转容积灌装机灌装控制流程的研究,解决容积式灌装受油温影响大的难题,进一步提高灌装精度。设计了一套基于西门子PLC的伺服在线调整机构,通过检测油温变化及灌装重量,按一定算法实时调整环形槽的倾斜度,从而控制灌装精度。灌装精度得到改善,灌装精度及速度均达到要求。该设备经实际应用,工作可靠,有效地提高了生产效率。     

食源性混合病原菌生物被膜行为对金黄色葡萄球菌毒素因子转录水平的影响

以食源性病原菌(金黄色葡萄球菌、大肠杆菌和肠炎沙门氏菌)形成的混合菌生物被膜为研究对象,对其定性和定量检测,通过实时荧光定量PCR方法分别检测单一菌和混合菌生物被膜中金黄色葡萄球菌28种目的 毒素基因转录水平的变化.结果 表明,结晶紫染色法、银染法和扫描电镜法均表明混合菌在培养24 h时达到最大黏附度;混合菌生物被膜中...     

转光膜的制备及性能研究

为了研究转光膜的光学特性和机械性能,将两种不同的转光剂(A、B)添加到聚乙烯树脂中,采用母料法制备转光膜.通过测试转光膜的荧光光谱和机械性能,得出以下结论:与普通薄膜相比,转光膜有明显的转光效果;添加转光剂A制备的薄膜转光效果较好;添加少量的转光剂对薄膜的机械性能影响不大.     

混合式教学模式下大学英语教师的写作评改反馈研究

英语写作是制约大学英语教学效果的瓶颈。针对在大学英语教学中出现的学生的写作兴趣不足、写作任务敷衍、写作水平不高等现象,分析了在大学英语写作教学过程中教师对学生写作的评改反馈方面存在的问题,提出了大学英语线上和线下相结合的混合式教学模式下教师应该转变教学观念、重视语言输出,采用灵活性、准时性、持续性、靶向性的多模式作文评改反馈模式,帮助学生真正提高英语写作水平,进而提高大学英语的整体教学效果。     

转光膜性能研究相关问题的探讨

转光膜是一类可转换光波波长的功能膜,依据不同转光剂的转光原理、转光膜的制备工艺和主要性能及其应用效果,重点分析并总结了转光剂、转光母料和转光膜生产工艺中存在的主要问题,并提出了有效解决转光膜研究和应用问题的建议.     

一种新的半定规划的Mehrotra型预估矫正算法

Salahi等人提出了线性规划的一种新的Mehrotra型预估矫正算法．针对该算法在线性规划上具有很好的实际计算效果,本文将该算法推广到半定规划问题上．基于NT方向,利用Lya—punov算子,最后证明了算法的O（√nL）迭代复杂性．     

一种新型苹果果实特征提取算法

针对当前苹果特征提取常用的Hough算法存在运算复杂、实时性差等缺陷,提出了一种新型苹果果实特征提取算法。该算法利用一个滑动的高斯模板和苹果图像进行卷积运算提取苹果的圆形。试验及仿真结果表明,该方法可以实现单一、相邻和重叠3种情况下,苹果果实检测的高准确率,且在相邻并重叠的复杂情况下,其识别准确率也能达到94.1%,而在单个苹果的情况下,苹果果实的检测准确率可达96.6%,完全满足苹果实时、高效分级的需要。     

A machine learning-based algorithm for estimating the original corneal curvature based on corneal topography after orthokeratology

ObjectiveTo estimate the original corneal curvature after orthokeratology by applying a machine learning-based algorithm.MethodsA total of 497 right eyes of 497 patients undergoing overnight orthokeratology for myopia for more than 1 year were enrolled in this retrospective study. All patients were fitted with lenses from Paragon CRT. Corneal topography was obtained by a Sirius corneal topography system (CSO, Italy). Original flat K (K1) and original steep K (K2) were set as the targets of calculation. The importance of each variable was explored by Fisher’s criterion. Two machine learning models were established to allow adaptation to more situations. Bagging Tree, Gaussian process, support vector machine (SVM), and decision tree were used for prediction.ResultsK2 after one year of orthokeratology (K2_after) was most important in the prediction of K1 and K2. Bagging Tree performed best in both models 1 and 2 for K1 prediction (R = 0.812, RMSE = 0.855 in model 1 and R = 0.812, RMSE = 0.858 in model 2) and K2 prediction (R = 0.831, RMSE = 0.898 in model 1 and R = 0.837, RMSE = 0.888 in model 2). In model 1, the difference was 0.006 ± 1.34 D (p = 0.93) between the predictive value of K1 and the true value of K1 (K1_before) and was 0.005 ± 1.51 D(p = 0.94) between the predictive value of K2 and the true value of K2 (K2_before). In model 2, the difference was −0.056 ± 1.75 D (p = 0.59) between the predictive value of K1 and K1_before and was 0.017 ± 2.01 D(p = 0.88) between the predictive value of K2 and K2_before.ConclusionBagging Tree performed best in predicting K1 and K2. Machine learning can be applied to predict the corneal curvature for those who cannot provide the initial corneal parameters in the outpatient clinic, providing a relatively certain degree of reference for the refitting of the Ortho-k lenses.     

块三对角线性方程组的并行迭代解法

提出了一种求解系数矩阵为块三对角矩阵的线性方程组的适合于MIMD分布式存储的并行迭代算法.该算法将一个分块三对角线性方程组的系数矩阵进行适合并行计算的不完全分解,从而形成迭代格式.整个计算过程只在相邻处理机之间进行3次通信.并从理论上给出了该算法收敛的一个充分条件,最后在HP rx2600集群上进行了数值实验.结果表明,此算法是可行的,具有较好的收敛性与并行效率.     

一种用于无线传感器网络的基于距离的节点自定位算法

针对现存定位机制中定位误差大或有较高的硬件要求问题和无线传感器网络低成本、低功耗的特点,在TDOA技术的基础上,提出了一种用于无线传感器网络的基于距离的节点自定位算法.该算法采用限制测距信号的跳数和重复运行的方式,使定位更精确,减少网络流量和负载.     

A textile- based optical fiber sensor design for automotive seat occupancy sensing

In our previous publications, the response of perfluorinated (PF) graded index (GI) POFs (62.5/750, 62.5/490 μm) to bending, tensile loading, and cyclic loading was investigated. The results showed that Cytop-1 (62.5/750 μm) was more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to Cytop-2 (62.5/490 μm). In this study, a textile-based optical fiber sensor was designed and the effect of automotive seat covering including face material and foam backing on a sensor’s performance was analyzed. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21 N/cm², where PF GI POF (62.5/750 μm) was used as the POF material. The responses of the sensor in this interval were observed to be accurate and reproducible. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor response. Artificial neural network (ANN) was used for data analysis, and Qwiknet (version 2.23) software was used to develop ANNs. According to the results of Qwiknet, the prediction performances for training and testing data-sets were 75 and 83.33%, respectively.     

分块周期三对角矩阵逆矩阵的新算法

研究了分块周期三对角矩阵的逆问题.利用递归方法,将高阶分块周期三对角矩阵的求逆转化为低阶分块周期三对角矩阵的求逆,给出了求分块周期三对角矩阵的逆矩阵的一种新算法.通过算法的计算量的比较,新算法比直接求逆算法的计算量小.新算法的算法复杂度为4n2+0(n)次,而直接求逆的算法复杂度是5.5n2+0(n)次.算例表明新算法...     

Use of multivariate factor analysis to define new indicator variables for milk composition and coagulation properties in Brown Swiss cows

The aim of this study was to elucidate the structure of relationships between milk yield, composition, and coagulation properties of Brown Swiss cattle. Multivariate factor analysis was used to derive new synthetic variables that can be used for selection purposes. For this reason, genetic parameters of these new variables were estimated. Individual records on milk yield, fat and protein percentages, casein content, lactose percentage, somatic cell count, titratable acidity, and pH were taken on 1,200 Italian Brown Swiss cows located in 38 herds. Factor analysis was able to extract 4 latent variables with an associated communality equal to 70% of the total original variance. The 4 latent factors were interpreted as indicators of milk composition, coagulation, acidity, and mammary gland health, respectively. Factor scores calculated for each animal exhibited coherent patterns along the lactation and across different parities. Estimation of genetic parameters of factor scores carried out with a multiple-trait Bayesian hierarchical model showed moderate to low heritabilities (raging from 0.10 to 0.23) and genetic correlations (from −0.15 to 0.46). Results of the present study support the hypothesis of a simpler structure that controls, at least in part, the covariance of milk composition and coagulation properties. Moreover, extracted variables may be useful for both breeding and management purposes, being able to represent, with a single value for each animal, complex traits such as milk coagulation properties or health status of the mammary gland.     

A new candidate protein for high lysine content in wheat grain

Lysine is the most limiting essential amino acid in cereal grains, so that grain lysine content is important for human nutrition and livestock growth. Translation elongation factor 1α (EF‐1α) from cereal embryo was recently reported to be rich in lysine, and the possibility of using this protein as a marker for feed quality was explored in maize. In this study we used immunochemical methods to investigate the relationship between the content of EF‐1α and other proteins from wheat germ and lysine content in both hexaploid (bread) wheats and diploid wheat progenitors to the wheat A‐genome. The levels of grain lysine, as well as their variation between lines or cultivars, were greater for the diploid wheats. While there was a significant correlation between the levels of EF‐1α and grain lysine content, the binding of antibodies to a protein of M_r 37 000 showed a higher correlation. This protein was characterised by amino acid sequencing as fructose 1,6‐bisphosphate aldolase. The possibility of using fructose 1,6‐bisphosphate aldolase as a marker for feed quality and development of a simple ELISA for quantification of lysine in wheat is demonstrated. © 2000 Society of Chemical Industry     

硫酸盐木浆新型漂序及自动化操作控制

新型漂序A/DO-EOP-D1-P的A段能够去除桉木硫酸盐浆中80%以上的己烯糖醛酸,该漂序可降低二氧化氯消耗30%左右,废水COD可达25kg/t,AOX含量0.2kg/t.采用补偿卡伯因子、补偿白度控制原理,进行自动化操作控制稳定生产过程,使漂白浆质量稳定、消耗达到最低.树脂障碍、白度返黄、结垢、纤维束尘埃是生产中经常会遇到的问题,可采取工艺技术措施加以调整控制.