Real time remaining useful life prediction based on nonlinear Wiener based degradation processes with measurement errors

Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.

A Replication of the Effect of Error-based Grammar Instruction on Fourth-graders' Writing

Shoudong Feng made a study of the error-based grammar instruction on fifth-graders' writing. Both the short and long-term gains proved to be significant in all three major categories (mechanical,sentence structure and usage). This study explored whether the results Feng presented at the 2004 Annual Meeting of MSERA,U.S would be replicable in rural settings at different grade levels. Participants were 35 fourth-grade students in a rural elementary school. Students were asked to write an essay on the topic given by the researcher. Samples from the pretest were collected and analyzed for grammar errors. Then the researcher designed lessons based on the results and taught the lessons by using errors from the sample. Students wrote on a similar topic in the posttest. The researcher analyzed the grammar errors and compared the results. The results showed the number of errors reduced significantly,esp. the errors of spelling,sentence fragment,S-V agreement and homophone confusion. The probability that the difference was due to chance was less than 5%. The findings supported the hypothesis that the error-based grammar instruction has a positive effect on the accuracy of fourth-graders' writing.

NEW APPROACH FOR RELIABILITY-BASED DESIGN OPTIMIZATION:MINIMUM ERROR POINT

Conventional reliability-based design optimization （RBDO） requires to use the most probable point （MPP） method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as the minimum error point （MEP） method or the MEP based method, for reliability-based design optimization, whose idea is to minimize the error produced by approximating performance functions. The MEP based method uses the first order Taylor＇s expansion at MEP instead of MPP. Examples demonstrate that the MEP based design optimization can ensure product reliability at the required level, which is very imperative for many important engineering systems. The MEP based reliability design optimization method is feasible and is considered as an alternative for solving reliability design optimization problems. The MEP based method is more robust than the commonly used MPP based method for some irregular performance functions.

Applying DNA Computation to Error Detection Problem in Rule-Based Systems

As rule-based systems (RBS) technology gains wider acceptance, the need to create and maintain large knowledge bases will assume greater importance. Demonstrating a rule base to be free from error remains one of the obstacles to the adoption of this technology. In the past several years, a vast body of research has been carried out in developing various graphical techniques such as utilizing Petri Nets to analyze structural errors in rule-based systems, which utilize propositional logic. Four typical errors in rule-based systems are redundancy, circularity, incompleteness, and inconsistency. Recently, a DNA-based computing approach to detect these errors has been proposed. That paper presents algorithms which are able to detect structural errors just for special cases. For a rule base, which contains multiple starting nodes and goal nodes, structural errors are not removed correctly by utilizing the algorithms proposed in that paper and algorithms lack generality. In this study algorithms mainly based on Adleman’s operations, which are able to detect structural errors, in any form that they may arise in rule base, are presented. The potential of applying our algorithm is auspicious giving the operational time complexity of O(n*(Max{q, K, z})), in which n is the number of fact clauses;q is the number of rules in the longest inference chain;K is the number of tubes containing antecedents which are comprised of distinct number of starting nodes;and z denotes the maximum number of distinct antecedents comprised of the same number of starting nodes.

ANALYSIS OF TOOTH FORM ERROR OF EQUAL BASE CIRCLE BEVEL GEAR

The basic principle of equal base circle bevel gear (EBCBG) is illustrated simply Thetooth surface equation of EBCBG manufactured by end milling cutter with involute profile is de-rived. The tooth form error is analyzed on the basis of spherical involute

ON THE ERROR OF QUADRATURE FORMULAE FOR CAUCHY PRINCIPAL VALUE INTEGRALS BASED ON PIECEWISE INTERPOLATION

We consider the computation of the. Cauchy principal value mtegral by quadrature formulaeof compound type, which are obtained by replacing f by a piecewise defined function F,[;]. The behaviour of the constants m the estimates where quadrature error) is determined for fixed i and which means that not only the. order, but also the coefficient of the main term of is determined. The behaviour of these error constants is compared -with the corresponding ones obtained for the. method of subtraction of the singularity. As it turns out, these error constants have, in general, the same asymptotic behaviour.

Enriched goal-oriented error estimation for fracture problems solved by continuum-based shell extended finite element method

An enriched goal-oriented error estimation method with extended degrees of freedom is developed to estimate the error in the continuum-based shell extended finite element method. It leads to high quality local error bounds in three-dimensional fracture mechanics simulation which involves enrichments to solve the singularity in crack tip. This enriched goal-oriented error estimation gives a chance to evaluate this continuum- based shell extended finite element method simulation. With comparisons of reliability to the stress intensity factor calculation in stretching and bending, the accuracy of the continuum-based shell extended finite element method simulation is evaluated, and the reason of error is discussed.

无机化学中“酸碱解离”教学内容的重构探讨

依据素质教育中知识-能力-素质有机融合的思想指导,对《无机化学》酸碱解离内容进行重组,构建新的课程设计模块。内容重组扩充为5个模块,包括电解质溶液基础、酸碱理论概述、酸碱强度、弱酸弱碱解离平衡和酸碱滴定与误差基本概念。教学内容的重构在保证基本面知识结构完整的前提下与时俱进,从专业能力方面促进学生发展。

CBL联合纠错教学应用于妇产科规范化培训中的价值

目的分析以案例为基础的教学法(Case Based Learning,CBL)联合纠错教学应用于妇产科规范化培训中的价值。方法选取2022年1月—2023年12月在潍坊医学院附属医院妇产科轮转的40名规范化培训医师为研究对象,采用随机数表法将其分为两组,每组20名。对照组实施传统规范化培训,观察组实施CBL联合纠错教学规范化培训,对比两组医师专业理论知识考试成绩、临床技能操作考核成绩及满意度。结果观察组专业理论知识考试成绩高于对照组,差异有统计学意义(P<0.05);观察组病例问询、查体、病例分析、治疗计划分数及总分均高于对照组,差异有统计学意义(P均<0.05);观察组教学模式、学习兴趣、自学能力、表达沟通能力、团队协作能力评分均高于对照组,差异有统计学意义(P均<0.05)。结论在妇产科规范化培训中,采用CBL联合纠错教学方法具有显著的价值,能够提高住培医师的专业理论知识水平,增强他们在实践中的能力,并促进他们的自主学习和团队合作能力。

适用于智能家居的格上基于身份多方认证密钥协商协议

随着物联网应用的日益普及,物联网设备终端数量激增、种类多样、层次复杂,常处于不可控的环境之中,因此,确保数据传输过程的安全性和隐私性至关重要。对基于物联网架构的智能家居服务进行探讨得出,启用智能家居应用需涉及多个方面,如用户、云、物联网智能集线器(the IoT smart hub,ISH)和智能设备,它们需要多方验证以进行安全通信。由此提出了一种针对智能家居应用的格上基于身份多方认证密钥协商协议,并证明在eCK模型下是安全的。其安全性可以归约到环上带误差学习(ring learning with errors,RLWE)问题的困难性,能够抗量子计算攻击。所提协议由一个格上基于身份的加密方案转换而成,无须公钥证书,避免了部署一个庞大的公钥基础设施(public key infrastructure,PKI)。通过信息交互实现显式认证,且可具有一定的匿名性质,与其他相关的后量子格上多方认证密钥协商协议方案相比,该协议在安全性和执行效率方面更具优势。

Python在酸碱滴定分析教学中的应用

基于Python自主设计开发的图形用户界面(GUI)酸碱滴定学习软件,实现了一元强酸(碱)、一元弱酸(碱)、多元酸(碱)和混合酸(碱)等不同酸碱体系滴定曲线图像的可视化绘制,化学计量点和滴定突跃范围以及滴定误差的计算。软件的运用使得教学内容更加直观、形象化,有助于获得滴定曲线变化的感性认识,深刻理解其概念与原理。

Auxiliary Model Based Multi-innovation Stochastic Gradient Identification Methods for Hammerstein Output-Error System

Special input signals identification method based on the auxiliary model based multi-innovation stochastic gradient algorithm for Hammerstein output-error system was proposed.The special input signals were used to realize the identification and separation of the Hammerstein model.As a result,the identification of the dynamic linear part can be separated from the static nonlinear elements without any redundant adjustable parameters.The auxiliary model based multi-innovation stochastic gradient algorithm was applied to identifying the serial link parameters of the Hammerstein model.The auxiliary model based multi-innovation stochastic gradient algorithm can avoid the influence of noise and improve the identification accuracy by changing the innovation length.The simulation results show the efficiency of the proposed method.

基于多传感器的紧耦合三维室内定位与建图

即时定位与地图构建(SLAM)因其可以解决未知环境中的定位与地图构建问题,广泛应用于移动机器人领域。本文使用雷达、相机、IMU和轮式里程计提出了一种名为3D-MultiFus的SLAM方法。其中雷达-IMU-里程计子系统(Ls)快速构建全局地图的几何结构,通过最小化点到平面误差估计系统位置状态。相机-IMU-轮式里程计子系统(Vs)可剔除被遮挡或深度不连续的特征点,以最小化帧间地图光度误差进一步估计位姿状态,并可实现子图中点云地图的着色渲染。IMU与里程计融合后的数据、雷达系统点到平面误差和相机系统中光度误差以基于误差状态的迭代卡尔曼方式(ESIKF)实现数据紧耦合,从而在保证精度和鲁棒性的同时,实现快速定位与建图。为了验证本文算法的定位与建图精度,布置了室内运动实验场景并将3D-MultiFus算法与相关算法比较。仿真和实验结果表明,3D-MultiFus算法完成一次数据处理需185 ms,在运行效率上优于其他算法。在复杂的室内场景下,长时间运行定位首末位置误差仅0.0856 m,3D-MultiFus移动机器人的全局地图精度得到了较大的提升,所构建的全局地图具有较好的一致性。证明了所提出算法能够在室内场景中稳健可靠的工作。

酸碱滴定终点误差及软件解析

酸碱滴定的终点误差是分析化学理论教学中的重点和难点之一,目前通行的教材均按照不同的滴定体系,导出大量公式进行误差计算,不仅过程复杂,而且大都为近似计算。本文尝试推导一种统一以滴定剂体积表达的终点误差公式,并将滴定剂在到达计量点和滴定终点时所对应的体积予以数值化,以准确求取滴定终点误差值。相关实例显示,该法可大大降低计算难度,有效减轻教学负担。此外,本文提出采用MATLAB将算法程序化,以进一步提升教学效率。

星基增强系统单频服务性能评估方法

针对星基增强系统(SBAS)用户差分距离误差(UDRE)完好性参数评估时双频无电离层组合放大观测噪声的问题,提出伪距域完好性评估方法,该方法反映了SBAS电离层改正数和星历时钟改正数的综合影响。利用240天共100个国际全球导航卫星系统(GNSS)服务组织(IGS)测站的数据对美国广域增强系统(WAAS)和欧洲地球静止轨道导航重叠服务(EGNOS)的性能进行评估。结果表明:WAAS和EGNOS格网电离层垂直误差(GIVE)参数的完好性分别为99.96%和99.91%,电离层延迟改正精度达到0.56 m。WAAS和EGNOS伪距域完好性优于99.999%,经改正后的GPS用户测距误差(URE)精度达到0.34 m。WAAS 95%的水平和垂直定位误差为1.19 m和1.72 m,EGNOS的则为1.18 m和1.68 m。评估时段内均未发生完好性风险事件,验证了测地型接收机用于SBAS服务性能评估的可行性。WAAS在一类垂直引导进近(APV-I)阶段的定位精度平均可用性为99.9%,二类垂直引导进近(APV-II)阶段在服务中心区域的定位精度可用性为80%~95%;EGNOS APV-I阶段平均定位精度可用性为99.9%,APV-II阶段平均定位精度可用性为94.2%,可用性较高,主要是由于EGNOS评估测站多处于服务区中心。SBAS定位精度可用性在服务区边缘部分下降较明显。

深度学习在DNA存储读段重建的应用

DNA存储技术是一项着眼于未来的具有划时代意义存储技术,它将数字信息编码为核苷酸序列,然后通过化学合成将序列写入DNA分子,最后通过DNA测序技术读取信息。相较于电子存储技术,其在信息密度、数据安全性以及保存年限等方面具有极大的优势。然而在DNA存储技术的数据读取端,测序读段存在着大量碱基替换、插入和删除错误,因此需进行读段重建来恢复原始数据。读段重建方法要求高成功率以及一定的时效性,以实现文件可靠存取并提高DNA存储技术的读写效率。文章介绍了现有的基于深度学习的读段重建模型,通过对模型架构、重建理念以及纠错能力等方面的比较指出了目前研究的局限性,并展望了未来深度学习在读段重建中可能的研究方向。

基于ELM-AE和BP算法的极限学习机特征表示方法

基于极限学习机自编码器(extreme learning machine based autoencoder,ELM-AE)和误差反向传播(back propagation,BP)算法,针对ELM提出了一种改进的特征表示方法。首先,使用ELM-AE以无监督的方式学习紧凑的特征表示,即ELM-AE输出权重;其次,利用ELM-AE输出权重来初始化BP神经网络的输入权重,然后对BP网络进行监督训练;最后,用微调的BP网络输入权重初始化ELM的输入权重参数。在MNIST数据集上的实验结果表明,采用BP算法对ELM-AE学习的参数进行约束,可以得到更紧凑且具有判别性的特征表示,有助于提高ELM的性能。

5G非地面网络相关误差矢量幅度标准测试模型分析

针对泛在通信和万物智联的发展需求,地面5G蜂窝通信系统和非地面网络系统实现优势互补、融合发展、资源共享。非地面网络是一种全新的形态,文中先讨论5G非地面网络系统元素及相关应用场景,接着根据5G基站的测试方法和一致性要求,来分析误差矢量幅度测试的方法及相关指标,通过自主设计的程序生成的测试波形与商业软件生成的测试波形进行比对,从信噪比、信道带宽以及子载波间隔三个方面分析其对误差矢量幅度的影响。为非地面网络设备的设计研发提供基于3GPP最新标准的测试方法,可为相关设备大规模量产节省开销。

地基空间目标监视雷达大气折射误差修正方法研究

大气介质垂向非均匀分布会使穿行其中的电磁波发生折射现象,尤其是其中的对流层和电离层,可造成电磁波传播延迟及路径弯曲,进而导致地基空间目标监视雷达测距和测角误差。本文基于射线追踪法实现了大气折射误差建模,推导了雷达测距和测角误差关于大气折射指数垂向分布的精确表达式,并详细阐述了地基空间目标监视雷达大气折射误差修正原理及流程,相比于传统的误差近似模型及修正方法,本文所提出的误差模型更准确、修正方法更有效。基于对流层和电离层模型获取大气折射指数垂向分布特性曲线,进行大气折射误差数值仿真,结果表明,本文方法在大气分层不同间隔取值下的误差补偿精度更高、性能更稳健,特别是在低仰角情况下,其性能优势更加明显。

BGG^(+)14属性基加密方案的模数分析

目的 分析BGG^(+)14属性基加密方案中模数的选取对其安全性的影响。方法 通过假定模数为合数及设定联合差错向量,利用BGG^(+)14属性基加密方案的密文结构,根据模数的分解特点展开模运算。结果与结论运算结果表明,如果模数是合数,且有一个小因数,则没有解密权限的用户可以成功得到明文,验证了模数为素数的必要性,为格上属性基加密方案的设计提供理论参考。