Consistency check of degradation mechanism between natural storage and enhancement test for missile servo system

Reliability enhancement testing(RET) is an accelerated testing which hastens the performance degradation process to surface its inherent defects of design and manufacture. It is an important hypothesis that the degradation mechanism of the RET is the same as the one of the normal stress condition. In order to check the consistency of two mechanisms, we conduct two enhancement tests with a missile servo system as an object of the study, and preprocess two sets of test data to establish the accelerated degradation models regarding the temperature change rate that is assumed to be the main applied stress of the servo system during the natural storage. Based on the accelerated degradation models and natural storage profile of the servo system, we provide and demonstrate a procedure to check the consistency of two mechanisms by checking the correlation and difference of two sets of degradation data. The results indicate that the two degradation mechanisms are significantly consistent with each other.

Thermodynamic Consistency Test for Binary Gas ＋ Water Equilibrium Data at Low and High Pressures

Phase equilibrium in binary gas + water mixtures over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. For modeling, the Peng-Robinson equation of state was used and the Wong-Sandler mixing rules were incorporated into the equation of state parameters. In the Wong-Sandler mixing rules the van Laar model for the excess Gibbs energy was applied. In addition, a reasonable and flexible method is applied to test the thermodynamic consistency of pressure-temperature-concentration(P-T-x) data of these binary mixtures.Modeling is found acceptable in all cases, meaning that deviations in correlating the pressure and the gas phase concentration are low. For all cases the thermodynamic consistency method gives a clear conclusion about consistency or inconsistency of a set of experimental P-T-x data.

Data Consistency Tests through the Use of Neural Networks and Virial Equation. Application of the Proposed Methodology to Critical Study of Density Data

This paper focuses on a very important point which consists in evaluating experimental data prior to their use for chemical process designs. Hexafluoropropylene P, ρ, T data measured at 11 temperatures from 263 to 362 K and at pressures up to 10 MPa have been examined through a consistency test presented herein and based on the use of a methodology implying both neural networks and Virial equation. Such a methodology appears as very powerful to identify erroneous data and could be conveniently handled for quick checks of databases previously to modeling through classical thermodynamic models and equations of state. As an application to liquid and vapor phase densities of hexafluoropropylene, a more reliable database is provided after removing out layer data.

CONSISTENCY OF MLE OF THE PARAMETER OF EXPONENTIAL LIFETIME DISTRIBUTION FOR RANDOM CENSORING MODEL WITH INCOMPLETE INFORMATION

In this paper, we have discussed a random censoring test with incomplete information, and proved that the maximum likelihood estimator(MLE) of the parameter based on the randomly censored data with incomplete information in the case of the exponential distribution has the strong consistency.

Image segmentation by level set evolution with region consistency constraint

Image segmentation is a key and fundamental problem in image processing,computer graphics,and computer vision.Level set based method for image segmentation is used widely for its topology flexibility and proper mathematical formulation.However,poor performance of existing level set models on noisy images and weak boundary limit its application in image segmentation.In this paper,we present a region consistency constraint term to measure the regional consistency on both sides of the boundary,this term defines the boundary of the image within a range,and hence increases the stability of the level set model.The term can make existing level set models significantly improve the efficiency of the algorithms on segmenting images with noise and weak boundary.Furthermore,this constraint term can make edge-based level set model overcome the defect of sensitivity to the initial contour.The experimental results show that our algorithm is efficient for image segmentation and outperform the existing state-of-art methods regarding images with noise and weak boundary.

Model Checking-Based Testing of Web Applications

A formal model representing the navigation behavior of a Web application as the Kripke structure is proposed and an approach that applies model checking to test case generation is presented. The Object Relation Diagram as the object model is employed to describe the object structure of a Web application design and can be translated into the behavior model. A key problem of model checking-based test generation for a Web application is how to construct a set of trap properties that intend to cause the violations of model checking against the behavior model and output of counterexamples used to construct the test sequences. We give an algorithm that derives trap properties from the object model with respect to node and edge coverage criteria.

On consistency and ranking of alternatives in uncertain AHP

This paper introduces uncertainty theory to deal with non-deterministic factors in ranking alternatives. The uncertain variable method (UVM) and the definition of consistency for uncertainty comparison matrices are proposed. A simple yet pragmatic approach for testing whether or not an uncertainty comparison matrix is consistent is put forward. In cases where an uncertainty comparison matrix is inconsistent, an algorithm is used to generate consistent matrix. And then the consistent uncertainty comparison matrix can derive the uncertainty weights. The final ranking is given by uncertainty weighs if they are acceptable;otherwise we rely on the ranks of expected values of uncertainty weights instead. Three numerical examples including a hierarchical (AHP) decision problem are examined to illustrate the validity and practicality of the proposed methods.

Consistency analysis of accelerated degradation mechanism based on gray theory

A fundamental premise of an accelerated testing is that the failure mechanism under elevated and normal stress levels should remain the same. Thus, verification of the consistency of failure mechanisms is essential during an accelerated testing. A new consistency analysis method based on the gray theory is pro- posed for complex products. First of all, existing consistency ana- lysis methods are reviewed with a focus on the comparison of the differences among them. Then, the proposed consistency ana- lysis method is introduced. Two effective gray prediction models, gray dynamic model and new information and equal dimensional （NIED） model, are adapted in the proposed method. The process to determine the dimension of NIED model is also discussed, and a decision rule is expanded. Based on that, the procedure of ap- plying the new consistent analysis method is developed. Finally, a case study of the consistency analysis of a reliability enhancement testing is conducted to demonstrate and validate the proposed method.

高超声速飞行器热-结构试验若干关键技术

热-结构试验是高超声速飞行器研制过程中不可或缺的环节。本文在给出热-结构试验内涵与特征的基础上,结合热-结构试验典型科目介绍,呈现了热-结构试验体系总体架构,为全面了解热-结构试验提供参考;其次重点分析了当前热-结构试验中亟待突破的时变超高温热载实现、局部热载大梯度模拟以及时/频域载荷协同等7大关键技术。

14台POCT血气分析仪与中心实验室检测结果的一致性分析

目的分析14台床旁检测(POCT)血气分析仪和中心实验室血气分析仪检测结果的一致性。方法采用中心实验室血气分析仪及14台POCT血气分析仪分别检测3个浓度水平质控品,每天检测2次,连续检测4 d,共24次,根据检测结果计算pH、动脉血二氧化碳分压(PCO_(2))、动脉血氧分压(PO_(2))、K^(+)、Na^(+)、Cl^(-)、Ca^(2+)的均值、标准差和变异系数等;计算14台POCT血气分析仪检测结果与中心实验室检测结果的偏倚及偏倚率;应用ANOVA检验、Passing-Bablok回归分析对14台POCT血气分析仪与中心实验室检测结果一致性进行分析评价。结果14台POCT血气分析仪各比对项目检测结果的变异系数均小于生产商声明的性能范围。14台POCT血气分析各比对项目的检测结果与中心实验室的偏倚均小于国家卫生健康委员会临床检验中心室间质量评价标准。14台POCT台血气分析各比对项目的检测结果比较,差异均无统计学意义(P>0.05)。14台POCT血气分析仪检测结果与中心实验室pH值、PCO_(2)、PO_(2)、K^(+)、Na^(+)、Cl^(-)、Ca^(2+)检测结果模拟回归方程的截距和斜率均在95%置信区间,且P>0.05,与中心实验室检测结果具有高度的一致性。结论14台POCT血气分析仪具有良好的精密度,且14台POCT血气分析仪之间及与中心实验室间均具有较好的一致性。

区间划分改进相似性的发动机剩余寿命预测

针对传统相似性匹配方法易引入伪相似发动机导致预测精度不高的问题,提出一种结合发动机性能退化特点与相似性匹配特点的区间划分改进相似性剩余寿命(RUL)预测方法。利用堆栈自编码器基于选择的参数构建健康指数;根据测试发动机的已知运行循环进行区间划分,利用传统相似性匹配方法进行初步筛选;对于不同区间下的测试发动机,分别使用不确定性修正和退化一致性检验去除初选参考发动机中的异常发动机,得到最终的剩余寿命预测结果。利用NASA的C-MAPSS数据集进行验证,结果表明:所提方法的预测精度比当前相似性匹配方法提升了34%,证明了方法的有效性。

2021—2023年高考物理试题与《课程标准》一致性研究

采用SEC模式,对2021—2023年高考物理全国甲卷、乙卷与《课程标准》进行一致性研究。结果表明:6套试卷中的重点知识和主干知识内容与《课程标准》的一致性程度较高,认知水平与《课程标准》的一致性也较高,符合高考这一选拔性考试的特点;试卷内容主题呈现了集中度较高、稳定性较强的特点,注重考查重点和主干知识;试卷整体认知水平与《课程标准》一致性较高,符合学业质量标准要求,但不同模块试题的认知水平与《课程标准》的一致性存在偏差。基于此,建议物理教学严格依据《课程标准》要求,强化必备知识教学,培养学生核心素养;创设丰富的教学情境,聚焦学生物理能力与思维品质;合理设计教学梯度,注重学习进阶发展,提升学业质量水平。

爱丁堡观察性步态评估量表在脑性瘫痪儿童中的信度与效度检验

目的:研究爱丁堡观察性步态评估量表(Edinburgh visual gait score,EVGS)的信度,并与三维步态分析进行比较,评价其有效性;同时分析EVGS各项内部以及与脑性瘫痪(cerebral palsy,CP)儿童粗大运动功能分级系统(gross motor function classification system,GMFCS)的相关性,为EVGS在临床应用提供客观依据。方法:从2019年至2021年所有在同济大学附属养志康复医院三维步态分析实验室进行三维步态分析的727例痉挛型CP儿童中随机抽取20例CP,分别由4名不同经验背景的评估者采用EVGS对20例CP的步行视频进行评估,并在间隔1个月后再次评估同一视频。采用同类相关系数分析(intragroup correlation coefficient,ICC)检验4名评估者的间信度,以及同一评估者的重测信度;采用Spearman等级相关系数检验EVGS总分及各项与三维步态分析数据和GMFCS之间的相关性。结果:评估者间第一次评估ICC值为0.947(P<0.001),第二次评估ICC值为0.952(P<0.001),两次评定结果均显示不同评估者对同一组视频采用EVGS的一致性结果较好。各评估者前后两次重测结果显示ICC系数均≥0.75(P<0.0010),表明间隔1个月,同一评估者前后两次评估结果具有较高一致性。相关性分析结果发现,EVGS与三维步态分析结果为中等相关,在校学生评估的总分与校标相关性最大。EVGS与GMFCS等级具有相关性。EVGS各项内相关性分析结果表明,足、骨盆及躯干控制的评估分项对EVGS评估整体步态的结果具有影响。结论:EVGS量表的评估者间信度以及同一评估者重测信度均具有较高可信性,未有丰富的临床经验背景下的评估者使用EVGS同样可以达到较高信效度。相关性分析结果表明,EVGS评估结果的准确性仍存在不足,EVGS评估结果与CP儿童运动功能障碍水平具有相关性,在设备有限情况下,EVGS可以作为步态分析的替补工具,是目前较为可靠的观察性步态评估量表之一。

微动敏感床垫式睡眠监测系统诊断阻塞性睡眠呼吸暂停及睡眠参数一致性评价

目的评价微动敏感床垫式睡眠监测系统(MSMSMS)在阻塞性睡眠呼吸暂停(OSA)诊断及睡眠评估中多参数与多导睡眠监测(PSG)相比的一致性。方法67例拟诊OSA的受试者同步使用PSG及MSMSMS记录多导睡眠参数,比较两者在OSA诊断及分度上的一致性,以及分别在呼吸事件、血氧事件、睡眠基本信息及睡眠结构参数上的一致性。计量资料采取了配对t检验,Bland-Altman分析以及组内相关系数(ICC),等级资料采取了weighted kappa分析。结果MSMSMS与PSG对照,诊断轻度以上、中度以上、重度OSA的曲线下面积分别为1、0.999和0.967(P<0.001);两种分层诊断结果的weighted kappa系数为0.841(95%CI:0.766~0.928,P<0.001)。其中呼吸暂停低通气指数(AHI)、呼吸暂停指数(AI)以及血氧指标组内相关系数分别为0.967(0.943,0.980)、0.937(0.900,0.961)、0.900(0.837,0.939)和0.936(0.891,0.962);两者在除低通气指数(HI)[0.181(-0.032,0.387),P=0.036]外的其他呼吸事件和血氧指标判读上具有很高的一致性(P<0.001);在睡眠结构的判读上,两者在浅睡眠比例和时间、深睡眠时间上具有中等程度的一致性。结论MSMSMS与PSG在OSA诊断和分度中具有高的敏感度和特异度。除了呼吸事件和血氧指标具有较强的一致性外,MSMSMS在评判OSA患者的睡眠结构上也有一定的意义。

固体火箭发动机真实热环境下EPDM绝热层烧蚀计算与试验研究

基于Hertz弹性碰撞理论和Thornton弹塑性假设,导出了粒子碰撞炭层过程中的压痕硬度理论表达式,根据弯管试验数据和试件扫描电镜分析提出了临界速度模型,对于三元乙丙橡胶(EPDM)炭化后形成的多孔炭化结构,结合裂纹侵蚀理论提出了两相流非完全弹性碰撞多孔炭化层体烧蚀计算模型。设计了用于验证烧蚀计算模型的模拟发动机旋转过载试验,保证了模拟发动机和真实发动机的天地一致性。结果表明:在模拟发动机真实飞行过程的热环境下,计算结果与实测结果能够基本吻合。研究结果对固体火箭发动机绝热结构的设计具有工程指导意义。

基于近红外光谱一致性检验模型鉴别银杏叶提取物片

目的 利用近红外光谱(NIR)法建立进口药品银杏叶提取物片的一致性检验模型。方法 通过对国外A企业生产的46批银杏叶提取物片进行光谱采集,运用OPUS7.8光谱分析软件对建模光谱图进行二阶导数和矢量归一化预处理,并采用国产不同企业同规格银杏叶片验证模型,建立银杏叶提取物片的近红外一致性检验模型。结果 建立的国外A企业样品近红外一致性模型能鉴别该厂家生产的银杏叶提取物片。结论 利用一致性检验方法,成功建立了国外A企业生产的银杏叶提取物片一致性检验模型,适用于该品牌银杏叶提取物片快速筛查。

鸡白痢沙门氏菌自制抗原的制备及检测效果评价

为了评价鸡白痢沙门氏菌自制抗原的检测效果,试验从通过特异性凝集试验和非特异性凝集试验筛选结果中随机选择1株鸡白痢沙门氏菌临床分离株SP-41,与鸡白痢沙门氏菌标准菌株CVCC1792按照1∶1比例混合,采用平板凝集试验和微量凝集试验两种方法分别制备染色抗原和凝集抗原,并以100份鸡血清样品为检测对象,比较了自制抗原、鸡白痢鸡伤寒多价染色平板凝集试验抗原(以下简称为商品染色抗原)的检测结果及其与D群沙门氏菌抗体ELISA试剂盒检测结果的一致性。结果表明:商品染色抗原、自制染色抗原、自制凝集抗原和D群沙门氏菌抗体ELISA试剂盒检测的阳性率分别为50%、78%、40%和72%。商品染色抗原Cohen’s kappa系数仅为0.08,提示一致性较差;自制染色抗原和自制凝集抗原的Cohen’s kappa系数为分别为0.363和0.375,一致性一般。自制染色抗原检测结果的阳性符合率最高,可达87.50%;而自制凝集抗原的阴性符合率更高,可达96.43%。说明试验成功制备了鸡白痢沙门氏菌染色抗原和凝集抗原;与商品染色抗原相比,自制抗原与D群沙门氏菌抗体ELISA试剂盒的检测结果一致性更高。

含有机质土-金属界面黏附特性与机制研究

土中有机质的存在对土-金属界面黏附有显著影响,但其影响规律及机制尚缺乏系统研究。通过在蒙脱石、伊利石和高岭土中添加泥炭,配置了不同矿质、有机质含量的黏性土样。利用MC-100型拉力试验机测试了不同含水率土-金属界面黏附力。试验结果表明:在塑限至液限含水率范围内,黏附力F与含水率w的关系曲线为典型的“钟型”;有机质含量wu增大会导致F-w曲线由高陡变扁平;土样峰值黏附力Fmax随有机质含量wu变化可分为3个阶段:波动或缓慢下降(上升)阶段、急剧下降阶段和趋于稳定阶段。利用傅积平法测试了3种黏土矿物对有机质的饱和吸附量,从而明确了有机质在土中赋存形态随有机质含量变化的过程。机理分析表明:除了有机质含量外,有机质在土中的赋存形态对土样宏观黏附力也有显著影响。最后对分布于昆明地铁5号线沿线的天然泥炭土-金属界面黏附力进行了测试,得出其黏附力较小、黏附风险较小的结论,盾构机穿越泥炭土层没出现严重黏附刀盘或堵塞现象验证了该结论。

黄土区无水文资料小流域设计洪水计算方法

兰州地区大部分季节性沟道没有相应水文资料,无法获取准确的洪峰流量,给沟道治理和管理带来很多不便。因此,建立适用于黄土区无水文资料小流域设计洪峰流量计算方法对流域防灾减灾工作具有重要意义。以甘肃兰州地区无水文资料山洪沟道为研究对象,结合甘肃省科学院地质自然灾害防治研究所调查评价数据,通过Kendall协同系数检验和灰色关联分析,分别对沟道流域特征参数的一致性和特征参数与设计洪水计算相关性进行检验分析,选取沟道面积与主沟道长两个特征参数建立适用于兰州市山洪沟道设计洪峰流量计算经验公式。结合兰州市洪水经验公式法和“铁一院”法对比分析,3种计算方法两两对比均值误差分别为:新经验公式法-兰州洪水经验公式相对误差均值约14.4%、新经验公式法-“铁一院”法相对误差均值约17.8%、兰州洪水经验公式法-“铁一院”法相对误差均值约20.3%,新经验公式计算结果介于兰州洪水经验公式与“铁一院”法之间,具有一定准确性及合理性,能够更加高效、便捷地进行设计洪峰流量推求。同时新经验公式推求设计洪峰流量仅涉及两个特征参数且可准确量化。

层次分析法中判断矩阵应用的场景化教学设计——以供应商综合评价为例

判断矩阵是层次分析法的核心,在多因素综合评价决策中有着重要应用。然而,现有关于判断矩阵的教学,忽略了一致性检验未通过应当如何重新构建的问题,致使学生难以形成系统认知,进而影响学生的实际应用。文章根据学生对判断矩阵的学习与掌握逻辑,从判断矩阵的概念、性质、构建、检验与调整等知识点进行了系统化梳理,并通过编制的“供应商综合评价”案例,特意设置一些有违一致矩阵性质的数据,让学生体会判断矩阵的构造原则、检验步骤和调整思路,加深对判断矩阵的构建与检验要点的理解,能熟练应用判断矩阵解决多因素综合决策问题。