Modified filter for mean elements estimation with state jumping

To investigate the real-time mean orbital elements(MOEs)estimation problem under the influence of state jumping caused by non-fatal spacecraft collision or protective orbit trans-fer,a modified augmented square-root unscented Kalman filter(MASUKF)is proposed.The MASUKF is composed of sigma points calculation,time update,modified state jumping detec-tion,and measurement update.Compared with the filters used in the existing literature on MOEs estimation,it has three main characteristics.Firstly,the state vector is augmented from six to nine by the added thrust acceleration terms,which makes the fil-ter additionally give the state-jumping-thrust-acceleration esti-mation.Secondly,the normalized innovation is used for state jumping detection to set detection threshold concisely and make the filter detect various state jumping with low latency.Thirdly,when sate jumping is detected,the covariance matrix inflation will be done,and then an extra time update process will be con-ducted at this time instance before measurement update.In this way,the relatively large estimation error at the detection moment can significantly decrease.Finally,typical simulations are per-formed to illustrated the effectiveness of the method.

A simplified two-dimensional boundary element method with arbitrary uniform mean flow

To reduce computational costs, an improved form of the frequency domain boundary element method（BEM） is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitrary orientation. The boundary integral equation（BIE） representation solves the two-dimensional convected Helmholtz equation（CHE） and its fundamental solution, which must satisfy a new Sommerfeld radiation condition（SRC） in the physical space. In order to facilitate conventional formulations, the variables of the advanced form are expressed only in terms of the acoustic pressure as well as its normal and tangential derivatives, and their multiplication operators are based on the convected Green＇s kernel and its modified derivative. The proposed approach significantly reduces the CPU times of classical computational codes for modeling acoustic domains with arbitrary mean flow. It is validated by a comparison with the analytical solutions for the sound radiation problems of monopole,dipole and quadrupole sources in the presence of a subsonic uniform flow with arbitrary orientation.

STUDY ON THE SEPARATION AND EXTRACTION MECHANISM OF RARE EARTH ELEMENTS BY MEANS OF REVERSED-PHASE PAPER CHROMATOGRAPHY

Reversed-phase paper chromatography technique is used for study on the extraction mechanism and sep- aration of rare earth elements.As the stationary phase,chromatographic paper strips are impregnated with a solution of monomyristyl phosphoric acid (MPA) in chloroform.Mineral acids are used as developers. The effect of concentration of acids and/or salts upon R_f has been investigated.According to the re- sults of R_f values for a given rare earth element in various acids,the order of extraction ability is HCl>HNO_3>H_2SO_4.A tetrad effect is clearly observed.for the R_f value of rare earth elements.The effects of other parameters on the R_f value,such as the quantities of extractant retained by the paper and the temperature are also examined.Based on the determination of the molar ratio of MPA to rare earth elements and the number of H^+ ions released in extraction reaction,a reasonable mechanism is proposed.The mutual separation of heavy rare earth elements will be better than that of the light rare earth group because of the larger separation coefficient of the former.A mixture of Ho-Er-Tm-Lu is successfully separated by the present method.

Short-Term Orbit Prediction with J₂and Mean Orbital Elements

An analytical theory for calculating perturbations of the orbital elements of a satellite due to J2 to accuracy up to fourth power in eccentricity is developed. It is observed that there is significant improvement in all the orbital elements with the present theory over second-order theory. The theory is used for computing the mean orbital elements, which are found to be more accurate than provided by Bhatnagar and taqvi’s theory (up to second power in eccentricity). Mean elements have a large number of practical applications.

基于D-S证据理论的岩爆预测方法研究

为了有效预测岩爆,提出基于D-S证据理论的岩爆预测方法.首先,选取与岩爆发生相关的6个指标因素作为证据体,并通过模糊物元框架和正态型隶属度函数构建证据体的基本概率分配.然后,利用K均值将证据体分类,并提出簇内证据用传统方式融合而簇间证据用权重方式融合的组合融合规则,以减轻高冲突证据融合的不利影响.最后,将模型应用在秦岭终南山公路隧道2号竖井工程,且与经验方法对比.为了分析预测过程的不确定性和估计岩爆发生概率,采用蒙特卡洛模拟进行抽样仿真,并通过Spearman秩相关系数衡量输入指标的全局敏感性.研究结果表明:输入指标在不同的岩爆案例的影响程度差异较大且方向不同;5个岩爆案例的发生概率在40.8%~70.1%之间.该模型表现出优异的预测分类性能,可为深埋地下工程岩爆预测提供参考.

基于模糊C-means聚类的地球化学数据分析

采用数据挖掘技术中模糊C-means聚类算法,以地球化学元素为数据对象、样品分析结果为属性值,对某已知金矿区和锡矿区岩石样品的元素组合特征进行了分析。聚类分析得出的元素组合关系与已知地质资料相一致,表明模糊C-means聚类算法能够客观、有效地发现地球化学元素的组合特征。同时,对位于内蒙古地区某多金属成矿带的地球化学采样数据进行了分析,根据聚类结果推断该地区是寻找金、银多金属矿产资源的目标区域。

数据要素推进新质生产力实现的内在机制与路径研究

数据作为新型生产要素的价值越发凸显,会推动新质生产力的形成。数据要素通过自身作用及与其他生产要素融合发生作用,并渗透在生产、流通、消费、分配等社会生产过程,不仅在国内发挥出数据乘数效应,还通过跨境数据流通发挥出开放乘数作用,会显著地催生新质劳动资料、孕育新质劳动对象、创造新质劳动力,进而推动新质生产力涌现。然而,数据要素发展面临诸多障碍,如有效供给不足、市场化缓慢、科技创新不足、规范化偏弱、数字劳动力供给不足等问题,都在影响并制约着新质生产力的实现。为此,建议加强数据要素市场开发、推进数据要素市场化、加快数据规则规范构建、加快数据高质量人才培育,以期充分发挥出数据要素赋能效应,助力新质生产力的生成与发展。

中古“牵拉”概念场词义的演变分析

选取中古时期“牵拉”义词“引”“牵”“曳”“拽”“拖”“挽”六词为研究对象,从共时角度梳理使用情况并得出“牵”“引”为主导词,“挽”“曳”为主要词汇,“拖”“拽”为边缘词汇。进而分析概念要素并辨析词义差别:“引”指不限方向的广义牵拉;“牵”指拉着向前走;“曳”“拽”“拖”指横牵不能或不愿移动之物;“挽”指牵动无法移动的重物。并从认知角度揭示出“引”“牵”“拽”通过隐喻方式衍生出“牵拉”义。

基于改进犹豫模糊C-均值的图像分割

犹豫模糊C-均值(hesitant fuzzy C-means,HFCM)聚类算法在一定程度上处理了图像中不同像素块之间的不确定性,但由于其目标函数中不包含任何局部空间信息,因此对噪声比较敏感,当噪声较大时无法获得较好的分割精度.针对上述问题,提出了一种改进犹豫模糊C-均值(improved hesitant fuzzy C-means,IHFCM)的图像分割方法.首先给出了犹豫模糊元(hesitant fuzzy element)的补齐方法,然后提出了犹豫模糊元之间的相似性度量,利用犹豫模糊元之间的相似性度量构造了新颖的模糊因子融合到HFCM的目标函数中,新的模糊因子不仅考虑了局部窗口中的空间信息而且考虑了像素间的相似性,平衡噪声带来的影响且保留了图像细节.最后,在合成图像、BSDS500数据集图像以及自然图像上的分割实验结果表明,所提出的IHFCM算法对噪声有良好的鲁棒性,提升了分割精度.

黔西市50年主要气候要素变化趋势分析

文章以黔西市国家基本气象站1971-2020年主要气象要素观测值为研究资料,采用数理统计、线性回归、5年滑动平均、MK突变检验等方法分析50年平均气温、极端最高气温、极端最低气温、降水量、平均相对湿度、日照时数、蒸发量、平均风速等气象要素的年际变化特征、距平值、气候倾向率和突变检验。结果表明:黔西市1971-2020年平均气温、极端最高气温、极端最低气温、降水量、平均相对湿度、日照时数、蒸发量、平均风速的多年平均值分别为14.82℃、32.79℃、-4.15℃、956.25 mm、81.08%、1 129.54 h、1 063.08 mm、1.31 m/s;气候倾向率分别为0.026℃/a、0.033℃/a、0.40℃/a、-0.786 mm/a、-0.25%/a、-4.038 h/a、-11.243 mm/a、0.003 m/s/a;年平均气温、极端最高气温、极端最低气温的变化趋势在进入21世纪前期有明显的突变升高,降水量在2007年、平均相对湿度在1977年、日照时数在1991年、蒸发量在1992年有浅显的突变减少趋势,多年平均风速随着年份的变化没有明显的突变特征。

微分中值定理中思政元素的探讨

数学分析课程不仅传授数学知识,而且蕴含着丰富的思政元素。以微分中值定理教学为例,通过细致解读三大中值定理的核心内容,并结合实际问题中的应用,巧妙地融入哲学思想、价值观教育和科学家精神等思政元素。在教学实践中,通过将思想政治教育与数学分析教学的有机结合,旨在培养学生的数学思维品质,使其树立正确的世界观、人生观和价值观,同时激发学生对数学分析课程的学习兴趣和热情。

大体积混凝土底板微振动控制能力的测试与分析

为测试北京光源这一精密科学设施中大体积混凝土底板的微振动控制能力,通过在建设现场进行短期测试和24 h长期监测的方式对底板微振动水平和微振动控制能力进行了评估。结果表明:在2次短期测试过程中,底板表面微振动位移有效值主要分布在10~50 nm之间,而在24 h监测过程中,底板表面微振动位移有效值主要在分布20 nm以下;大体积混凝土底板对10 Hz以上垂直于地面方向的微振动及5 Hz以上水平向的微振动体现出较好的控制作用;大体积混凝土底板最大能够将垂直地面方向微振动水平降低24%,水平向微振动水平降低34%,底板对水平向微振动控制能力略优于对竖向微振动的控制能力。建立了二维简化有限元模型,讨论了改变混凝土层密度、刚度及厚度对底板微振动控制能力的影响,模拟结果表明在现有激励条件下,增大底板配筋层厚度或素混凝土层密度对底板竖向微振动控制能力无明显影响,但对水平向微振动控制能力产生不利影响。

变压器局部放电传播特性及监测点位的优化研究

局部放电超声波信号在电力变压器设备外壳上衰减严重,导致不同位置传感器接收的局部放电信号存在巨大差异,极大地影响了其在现场应用时的测量精度和检测效率。为此,本文采用有限元仿真软件建立油浸式电力变压器分区模型,得到局部放电超声波信号在油箱主面的分区规律,并形成变压器空间声压和分区声压的分布图谱。基于Pearson相关系数与K-means聚类的监测点位优化方法,优选出空间声压与分区声压敏感度最佳的监测点位,并进行对比测试。结果表明:A等级监测点的平均检测效率为86.0%,实现了变压器局部放电的高效检测,为超声波传感器布置点位的选择提供了新方法。

非法经营罪的教义学限缩

非法经营罪由于越权司法解释及法官滥用自由裁量权而在司法实践中不断异化扩张,对其进行刑法教义学限缩具有现实紧迫性。非法经营罪的异化扩张主要表现为司法者混淆本罪与他罪客体界限,对罪状要素存在任意解释和扩大解释现象。非法经营罪异化的根源在于司法,而不在立法,司法者过度重视刑法的法益保护机能,忽视自由保障功能,有悖罪刑法定原则,并且过度灵活的司法适用有滋生刑法工具主义之风险。刑法教义学的司法适用功能及立法促进功能为限缩本罪提供了有效的解决方案,对非法经营罪堵截条款的理解应遵循同质解释规则,并从体系解释的视角确立“明确罪名优先适用”的规则以解决法条竞合问题,在解释的过程中对立法进行体系内的反思,从而推动在立法上进一步限缩本罪的适用范围。

Geochemical and Geostatistical Studies for Estimating Gold Grade in Tarq Prospect Area by K-Means Clustering Method

Tarq geochemical 1:100,000 Sheet is located in Isfahan province which is investigated by Iran’s Geological and Explorations Organization using stream sediment analyzes. This area has stratigraphy of Precambrian to Quaternary rocks and is located in the Central Iran zone. According to the presence of signs of gold mineralization in this area, it is necessary to identify important mineral areas in this area. Therefore, finding information is necessary about the relationship and monitoring the elements of gold, arsenic, and antimony relative to each other in this area to determine the extent of geochemical halos and to estimate the grade. Therefore, a well-known and useful K-means method is used for monitoring the elements in the present study, this is a clustering method based on minimizing the total Euclidean distances of each sample from the center of the classes which are assigned to them. In this research, the clustering quality function and the utility rate of the sample have been used in the desired cluster (S(i)) to determine the optimum number of clusters. Finally, with regard to the cluster centers and the results, the equations were used to predict the amount of the gold element based on four parameters of arsenic and antimony grade, length and width of sampling points.

STOCHASTIC BOUNDARY ELEMENT METHOD IN ELASTICITY

The stochastic boundary element method is developed to analyze elasticity problems with random material and/or geometrical parameters and ran- domly perturbed boundaries. Based on the first-order Taylor series expansion, the boundary integration equations concerning the mean and deviation of the displace- ments are derived, respectively. It is found that the randomness of material param- eters is equivalent to a random body force, so the mean and covariance matrices of unknown boundary displacements and tractions can be obtained. Furthermore, the mean and covariance of displacements and stresses at inner points can also be obtained. Numerical examples show that the proposed stochastic boundary element method gives satisfactory solutions, as compared with those obtained by theoretical analysis or other numerical methods.

基于改进K-means算法的时间和地点识别

事件要素识别主要包括时间要素和地点要素的识别。目前,时间和地点要素的识别主要是利用机器学习的方法,但是基于机器学习的方法容易受到语料稀疏性的影响。提出了基于改进K-means算法的时间和地点识别。该方法主要是对K-means算法进行改进,先利用Canopy算法求出聚类的K值,再根据改进的算法进行聚类分析,最后利用词性进行优化处理,并得到实验结果。

“山水”泛指万物的易学探微

“山水”常被用以泛指一切自然景象,这与《周易》立象尽意的象征观念和天人交感的“三才”思想有着微妙的关系。由于天地玄远,不可骤观,古人在天人交感的具体实践中,受阴阳五行学说的影响,逐渐以“山水”作为“天地”的象征,“山水”由此成为以天地之象统摄万物的符号媒介。

Language Teaching and the Visual Element

Visual methods in language teaching have come in very quickly; their introduction has been hastened by the development of the electronic and mechanical means for displaying visual materials. And the learning of language and the teaching of meaning have been a long-lasting and significant topic in applied linguistics. In this paper several aspects of language teaching including main features of language learning, different ways for teaching of meaning etc. have been discussed. Then, the visual element in language teaching and different kinds of visual materials such as sound film, audio-visual courses, television will be introduced with an application of visual materials in real language class. Then, after the above discussion, the final conclusion will be arrived that the ultimate goal of language teaching is meaning and visual element can be of great importance in the creation of a real situation in language teaching.

考虑接触问题的多边形有限元重力坝抗震断裂研究

抗震断裂问题是混凝土重力坝的重要研究内容,数值模拟则是针对此类问题的主要研究方法,现有断裂算法存在计算效率较低,大多未考虑接触等问题。为此,构造了高效的平均值坐标插值多边形单元和接触薄层单元,并将二者耦合后用于结构裂缝扩展的数值模拟。该方法将具有奇异特性以及复杂几何区域网格自适应性强的多边形有限元方法与平均值坐标插值方法、局部多边形网格策略结合起来模拟裂缝扩展;通过等参子三角形方法进行数值积分,求解刚度矩阵;基于最大周向应力准则,采用混合断裂强度因子作为起裂判据;针对裂缝面间的接触问题,引入张剪状态下的黏聚力模型以及压剪状态下的光滑接触模型。基于上述方法,通过Matlab编程的方式开发出一套能模拟裂缝扩展的程序,并通过对含边裂缝的PMMA板试验和含预设裂缝的四点剪切梁试验的模拟,验证了程序的准确性与有效性。最后,以含有预设裂缝的柯伊纳混凝土重力坝为例,对其在是否考虑接触问题下裂纹扩展的情况进行了对比分析,结果表明该程序模拟裂缝真实准确,具有计算速度快、结果文件小等独特优势。