Augmented Eigenvector and Its Orthogonality of Linear Multi-rigid-flexibel-body System

The orthogonality of eigenvector is a precondition to compute the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method. For a linear multi-rigid-flexible-body system, the eigenfunction does not satisfy the orthogonality under ordinary meaning. A new concept--augmented eigenvector is introduced, which is used to overcome the orthogonality problem of eigenvectors of linear multi-rigid-flexible-body system. The constitution method and the orthogonality of augmented eigenvector are expatiated. After the orthogonality of augmented eigenvector is acquired, the coupling of coordinates in dynamics equations can be released, which makes it possible to analyze exactly the dynamic responses of linear multi-rigid-flexible-body system using the classical modal analysis method.

Firey linear combinations of convex bodies

For convex bodies, the Firey linear combinations were introduced and studied in several papers. In this paper the mean width of the Firey linear combinations of convex bodies is studied, and the lower bound of the mean width of the Firey linear combinations of convex body and its polar body is given.

Automated Extraction for Water Bodies Using New Water Index from Landsat 8 OLI Images

The extraction of water bodies is essential for monitoring water resources,ecosystem services and the hydrological cycle,so analyzing water bodies from remote sensing images is necessary.The water index is designed to highlight water bodies in remote sensing images.We employ a new water index and digital image processing technology to extract water bodies automatically and accurately from Landsat 8 OLI images.Firstly,we preprocess Landsat 8 OLI images with radiometric calibration and atmospheric correction.Subsequently,we apply KT transformation,LBV transformation,AWEI nsh,and HIS transformation to the preprocessed image to calculate a new water index.Then,we perform linear feature enhancement and improve the local adaptive threshold segmentation method to extract small water bodies accurately.Meanwhile,we employ morphological enhancement and improve the local adaptive threshold segmentation method to extract large water bodies.Finally,we combine small and large water bodies to get complete water bodies.Compared with other traditional methods,our method has apparent advantages in water extraction,particularly in the extraction of small water bodies.

Effect of Perturbations in Coriolis and Centrifugal Forces on the Non-Linear Stability of <i>L</i>₄in the Photogravitational Restricted Three Body Problem

Effect of perturbations in Coriolis and centrifugal forces on the non-linear stability of the libration point L4 in the restricted three body problem is studied when both the primaries are axis symmetric bodies (triaxial rigid bodies) and the bigger primary is a source of radiation. Moser’s conditions are utilized in this study by employing the iterative scheme of Henrard for transforming the Hamiltonian to the Birkhoff’s normal form with the help of double D’Alembert’s series. It is found that L4 is stable for all mass ratios in the range of linear stability except for the three mass ratios μc1, μc2 and μc3, which depend upon the perturbations ε1 and ε1 in the Coriolis and centrifugal forces respectively and the parameters A1,A2,A3 and A4 which depend upon the semi-axes a1,b1,c1;a2,b2,c2 of the triaxial rigid bodies and p, the radiation parameter.

基于单-多视图优化的足球球员三维姿态和体型估计

足球比赛场景的三维重建有助于观众自由切换视角,增加了互动性和沉浸感。针对足球比赛场景中的足球球员,提出一种三维姿态和体型估计方法。对球员的多视图图像使用训练好的部分注意力回归的三维人体估计(PARE)模型生成初始的三维姿态和体型估计,并使用人工标注的二维关节点作为优化目标。单-多视图优化操作利用蒙皮多人线性模型(SMPL)和正交投影的可微性,将球员的三维姿态和体型参数映射到二维关节点,计算其与人工标注之间的差异,再使用神经网络的反向传播算法更新三维姿态和体型参数,持续这些过程直到差异最小化。在自建的足球球员多视图数据集上的实验结果表明,该方法能够有效估计足球球员的三维姿态和体型,与人体网格恢复、在循环中优化SMPL、PARE等方法相比,二维关节点精度在单视图上提高了9.2%~37.5%,在多视图交叉验证中提高了34.9%~54.1%。

基于线性混合模型树在体质指数纵向轨迹中的应用

目的 探讨江苏省成年人体质指数纵向变化轨迹及分类。方法 基于中国营养健康调查数据,使用线性混合模型树探究江苏省18~65岁人群体质指数的变化轨迹及其分类情况。结果 线性混合模型树生成了13个节点,树的深度为6,分类节点为基线BMI、平均摄入卡路里、基线年龄。结论 线性混合模型树可以识别体质指数的变化轨迹,拓展了纵向数据动态变化的研究方法。

基于LQ模型的原发性肝癌立体定向放射治疗剂量学实验

目的:探讨肝癌立体定向放射治疗(SBRT)的剂量学效应是否符合线性二次(LQ)模型。方法:选取体外培养的人肝癌细胞株HepG2和Hep3B,给予生物有效剂量(BED)照射(6、8、10、12、14 Gy)。照射分割方式包括单次照射(模拟SBRT)和分次照射3次、5次(模拟IMRT)。检测辐照后存活分数反应不同分割方式的损伤效应;绘制生存曲线,观察不同分割方式对细胞增殖的影响;辐照后细胞划痕实验,观察不同分割方式对细胞侵袭和迁移能力的影响。结果:LQ模型在肝癌SBRT放疗的应用体外验证中出现明显的分离效应。对于HepG2细胞和Hep3B细胞,当BED<12 Gy(α/β=10 Gy)时,不同分割方式在损伤效应、增殖能力、侵袭能力上未显示出明显差异,SBRT符合LQ模型;当BED≥12 Gy时,单次分割相对于多次分割,显示出更高的损伤效应,即SBRT损伤效应高于IMRT。结论:SBRT在肝癌中适用LQ模型具有一定的剂量区间,超过该区间损伤效应高于LQ模型预测结果。

基于线性密集台阵的2023年甘肃积石山M_(S)6.2地震断层低速带研究

2023年12月18日,甘肃省积石山县发生M_(S)6.2逆冲型地震。该地震发生在祁连活动地块拉脊山北缘断裂带,在断裂两侧曾发生过20余次5级左右中强地震,地震活动频次高,因此研究拉脊山断裂带特征具有重要意义。根据拉脊山断裂走向和此次地震余震分布,在刘集乡布设一条线性密集台阵,利用不同方位的余震事件计算体波的走时延时和放大效应。结果表明,P波和S波分别存在6个采样点(约0.012 s)和15个采样点(约0.03 s)的走时延时,推断出台阵西侧存在一个约150 m宽近似垂直的断层低速带,且该结果与远震P波相似性系数矩阵结果一致。

刚体定轴转动理论教学中的类比法应用研究

基于刚体定轴转动和质点直线运动具有较为类似的特点,文章主要研究类比法在刚体定轴转动理论教学过程的应用。对于经典运动的两大领域——运动学和动力学,在教学实施的过程中,利用二运动数学形式上的相似性和物理量之间内在的联系,将较为难懂的转动理论中的角量与学生所熟悉的质点直线运动中的线量进行类比,借助理解质点直线运动的思维模式,深入理解刚体定轴转动的各物理量以及相应的物理规律,从而为此部分内容的教学提供一套较为可行的简易化范式。

武禽10肉鸭与亲本连城白鸭生长曲线拟合及肉用性能比较

为研究武禽10肉鸭配套系商品鸭生长发育规律,以亲本连城白鸭为对照,测定0~9周龄体重和9周龄屠宰指标、肉质指标,利用Logistic、Gompertz、Bertalanffy 3种非线性模型对体重进行生长曲线拟合。结果发现:(1)3种曲线模型对武禽10肉鸭配套系商品鸭和连城白鸭体重拟合效果均较好,拟合度均在0.98以上,其中武禽10肉鸭Gompertz模型拟合最佳(公鸭R^(2)=0.999,母鸭R^(2)=0.997),连城白鸭Bertalanffy模型拟合最佳(公鸭R^(2)=0.995,母鸭R^(2)=0.993);(2)武禽10肉鸭Gompertz模型拟合曲线中公、母鸭拐点体重分别为849.9、810.7 g,拐点周龄分别为3.9、4.1 w,最大周增重分别为294.9、268.3 g;连城白鸭Bertalanffy模型拟合曲线中公、母鸭拐点体重分别为528、601 g,拐点周龄分别为4.6、5.7 w,最大周增重分别为135、126 g;(3)屠宰结果显示,武禽10肉鸭较连城白鸭活体重提高80.90%,全净膛率提高2.97%,瘦肉率(胸肌率和腿肌率之和)提高20.31%(P<0.05);(4)肉质测定结果显示,武禽10肉鸭较连城白鸭胸肌蛋白质含量提高4.15%,肌内脂肪含量提高21.55%(P<0.05)。综合分析表明,武禽10肉鸭商品鸭早期生长速度快于连城白鸭,且9周龄产肉性能和肉品质均优于连城白鸭。该研究结论为验证武禽10肉鸭配套系的选育效果及商品鸭的饲养管理提供理论依据。

12月龄短角牛体重与主要体尺指标的相关性分析

本文旨在探究12月龄短角牛体重与主要体尺指标之间的相关性,构建多元回归方程,研究影响短角牛月龄的主要体尺指标。选取12月龄公牛163头,母牛261头,共424头短角牛体重、体高、十字部高、体斜长、胸围的体尺数据,使用最小二乘法对已知数据进行最佳线性拟合,构建多元回归方程并分析其相关性。结果显示,12月龄短角公牛的体重与各体尺指标的平均值均高于母牛;且体重与各体尺指标的回归关系达到极显著水平%(P%﹤0.01),多元线性回归方程拟合度较高。12月龄短角牛无论公母,其体重与各体尺指标之间均呈现不同程度的相关性,其中公牛的体高、十字部高、体斜长、胸围与体重的相关性高于母牛。12月龄短角公牛体重与体高、十字部高、体斜长、胸围呈极显著正相关(P﹤0.01),其中体重与胸围的相关性最大(r=0.902)。12月龄短角母牛的体重与体高、十字部高、体斜长、胸围之间均呈极显著正相关(P﹤0.01),其中体重与胸围相关性最大(r=0.823)。12月龄短角牛的体重与体高、十字部高、体斜长、胸围之间均呈极显著正相关(P﹤0.01),其中体重与胸围相关性最大(r=0.873)。

浅谈机器人异形焊钳电极搓动缺陷排除方法

机器人焊钳是自动化驾驶室拼焊线的一种重要装备,主要由焊接变压器、钳臂、气缸、握杆、电极等组成,焊钳结构通常根据驾驶室车身数模、车身拼焊线焊夹具进行设计。文章中机器人焊钳在驾驶室车身根据产品开发需求中遇到了特殊的结构,设计的机器人焊钳虽然能够完成既定的焊接工作,但是,操作中会出现焊点质量达不到焊接质量标准要求的情况。基于这一问题,文章通过对机器人焊钳结构特征进行分析,设计了一种能够将直线导轨滑块与焊钳结合的焊钳结构,以此来增强焊钳焊接的稳定性,提高驾驶室焊点的外观质量及焊接强度,为企业产品质量管控提供了必要的保障。

穿梭山体的线型项目水土保持方案汇水分析特点难点及方法

本文以沙荷路—盐排高速立交工程(二期)项目为例,对穿梭山体的线型项目的原始地形、工程施工建设新形成的边坡改变地形致使汇水方向发生改变进行了分析,根据排水出口承担的汇水面积对截排水沟规格及沉沙池缓冲沉淀效果进行校核及补充设计,以发挥水土保持效用,使施工期水土流失降至容许范围内。

THE DUAL BRUNN-MINKOWSKI INEQUALITIES FOR STAR DUAL OF MIXED INTERSECTION BODIES

In this article, some dual Brunn-Minkowski inequalities are established for star dual of mixed intersection bodies with respect to the harmonic p-combination and p-radial linear combination.

THE RECIPROCAL THEOREM AND LINEAR ELASTIC VARIATIONAL PRINCIPLES

In this paper classical linear elastic variational principles are systematically derivedfrom the reciprocal theorem and mixed variational principles of variations of boundaryconditions are given.

Restricted Three Body Problem with Stokes Drag Effect

The existence and stability of stationary solutions of the restricted three body problem under the effect of the dissipative force, Stokes drag, are investigated. It is observed that there exist two non collinear stationary solutions. Further, it is also found that these stationary solutions are unstable for all values of the parameters.

Data-Driven Nonlinear Control for Orbit Transfer: From the Earth to Moon and L4/5

From the recent thirty years, scientists will never stop exploring the outer space. To assist the development of travelling into the universe, I devote myself into providing theoretical support and future indications for designing the optimal orbit for satellite to travel in a Three-Body System. This paper offers the optimal orbit for satellite to change path in the earth-moon system. Also, it provides the path for the satellite to use the least fuel to go to the L4 and L5 Lagrange points. These inspiring results are obtained through several steps: to solve the problems caused by the non-linear character of Three-Body System, I use Koopman eigenfunction to change the system into a linear one. Data-driven method is adopted to find the most suitable Koopman eigenfunction to apply control. The traditional LQR operator for linear system is used to design the optimal orbit for the satellite.

Port-Hamiltonian Based Control of the Sun-Earth 3D Circular Restricted Three-Body Problem: Stabilization of the <i>L</i>₁Lagrange Point

In this paper, we use Port-Hamiltonian framework to stabilize the Lagrange points in the Sun-Earth three-dimensional Circular Restricted Three-Body Problem (CRTBP). Through rewriting the CRTBP into Port-Hamiltonian framework, we are allowed to design the feedback controller through energy-shaping and dissipation injection. The closed-loop Hamiltonian is a candidate of the Lyapunov function to establish nonlinear stability of the designed equilibrium, which enlarges the application region of feedback controller compared with that based on linearized dynamics. Results show that the Port-Hamiltonian approach allows us to successfully stabilize the Lagrange points, where the Linear Quadratic Regulator (LQR) may fail. The feedback system based on Port-Hamiltonian approach is also robust against white noise in the inputs.

基于DEM与MFBD双向耦合生物质成型模具疲劳寿命分析

根据环模成型机的实际攫取工况,考虑环模与压辊和物料间存在大量接触和碰撞的非线性力学行为,采用FFlex法建立柔性体动力学模型;建立环模成型机的DEM-MFBD双向耦合的模拟仿真模型,使结果更加接近实际情况。采用正交试验,分析环模转速、模辊间隙、颗粒粒径对颗粒所受压力的影响。结果表明:各因素对试验指标的影响按大小次序排列应当是最小模辊间隙、颗粒粒径、环模转速。分析不同参数对环模最大扭矩的影响,结果表明:环模转速在5~6 rad/s时,环模所受最大扭矩随着环模的转速增加而增加,而环模转速增加到6 rad/s后,环模所受最大扭矩随着环模转速的增加而减小;在颗粒粒径为2~2.4 mm时,随着颗粒粒径的增加,环模最大扭矩也不断增大。将EDEM-RecurDyn耦合得到的数据结果导入到Durability模块进行疲劳寿命分析,结果显示,环模比压辊更容易出现疲劳破坏。

皮山红羊脂尾性状特征及其与体重、体尺的相关性分析

皮山红羊是新疆和田地区的优良地方遗传资源,现存数量少,急需扩繁和选育,为掌握皮山红羊体重与体尺的相关性,试验以成年的皮山红羊为研究对象,通过SPSS 27.0软件分析公母羊的尾体积差异,根据尾体积大小进行分型;利用Persons法分析各性状间的相关性,利用逐步回归法估计公母羊体尺性状的模型决定系数,并构建多元线性回归方程。结果表明,公羊尾体积显著大于母羊(P<0.05),且公母羊尾型均可以分为小尾型、中尾型、大尾型;皮山红羊公羊的平均体尺指数与平均体重均高于母羊。公羊体重(y)与尾长(x_(5))的相关系数最大,为0.792,母羊体重(y)与胸围(x_(3))的相关系数最大,为0.895。公、母羊体重与体尺指标的最佳回归方程分别为:yy公=2.343x_(5)+0.364x_(3)-4.265(R^(2)=0.710,P<0.01)、y母=0.785x_(3)+0.395x_(10)-0.319x_(11)-37.072(R^(2)=0.835,P<0.01)。皮山红羊尾部性状与体重呈极显著正相关(P<0.01),说明皮山红羊尾部性状与体重密切相关,在皮山红羊选育和实际生产过程中,在重视体重选择的同时也应关注尾部性状。