3D Model Retrieval Method Based on Affinity Propagation Clustering

In order to improve the accuracy and efficiency of 3D model retrieval,the method based on affinity propagation clustering algorithm is proposed. Firstly,projection ray-based method is proposed to improve the feature extraction efficiency of 3D models. Based on the relationship between model and its projection,the intersection in 3D space is transformed into intersection in 2D space,which reduces the number of intersection and improves the efficiency of the extraction algorithm. In feature extraction,multi-layer spheres method is analyzed. The two-layer spheres method makes the feature vector more accurate and improves retrieval precision. Secondly,Semi-supervised Affinity Propagation ( S-AP) clustering is utilized because it can be applied to different cluster structures. The S-AP algorithm is adopted to find the center models and then the center model collection is built. During retrieval process,the collection is utilized to classify the query model into corresponding model base and then the most similar model is retrieved in the model base. Finally,75 sample models from Princeton library are selected to do the experiment and then 36 models are used for retrieval test. The results validate that the proposed method outperforms the original method and the retrieval precision and recall ratios are improved effectively.

Accurate calculation of electron affinity for S_3

The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q, 5, or 6), complete basis set extrapolation functions with two-parameters and three-parameters, together with considering the contributions due to the core-valence electron correlation, scalar relativistic effects, spin–orbit coupling, and zero-point vibrational corrections. Our calculations show that both the neutral S_3 and anion S_3^- have open forms with C_(2r) vsymmetry. On the basis of the stable geometries, the adiabatic electron affinity of S_3 is determined to be 19041(11) cm^(-1), which is in excellent agreement with the experimental data(19059(7) cm^(-1)). The dependence of geometries and electron affinity on the computation level and physical corrections is discussed. The present computational results are helpful to the experimental molecular spectroscopy and bonding of S_3.

Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.

Seedling Stage Corn Line Detection Method Based on Improved YOLOv8

[Objective]Crop line extraction is critical for improving the efficiency of autonomous agricultural machines in the field.However,traditional detection methods struggle to maintain high accuracy and efficiency under challenging conditions,such as strong light exposure and weed interference.The aims are to develop an effective crop line extraction method by combining YOLOv8-G,Affinity Propagation,and the Least Squares method to enhance detection accuracy and performance in complex field environments.[Methods]The proposed method employs machine vision techniques to address common field challenges.YOLOv8-G,an improved object detection algorithm that combines YOLOv8 and Ghost‐NetV2 for lightweight,high-speed performance,was used to detect the central points of crops.These points were then clustered using the Affinity Propagation algorithm,followed by the application of the Least Squares method to extract the crop lines.Comparative tests were conducted to evaluate multiple backbone networks within the YOLOv8 framework,and ablation studies were performed to validate the enhancements made in YOLOv8-G.[Results and Discussions]The performance of the proposed method was compared with classical object detection and clustering algorithms.The YOLOv8-G algorithm achieved average precision(AP)values of 98.22%,98.15%,and 97.32%for corn detection at 7,14,and 21 days after emergence,respectively.Additionally,the crop line extraction accuracy across all stages was 96.52%.These results demonstrate the model's ability to maintain high detection accuracy despite challenging conditions in the field.[Conclusions]The proposed crop line extraction method effectively addresses field challenges such as lighting and weed interference,enabling rapid and accurate crop identification.This approach supports the automatic navigation of agricultural machinery,offering significant improvements in the precision and efficiency of field operations.

基于仿射变换的奇异积分自适应单元细分法

边界元法已广泛应用于解决工程实际问题中,精确高效地计算奇异积分对于求解边界积分方程至关重要。为此,提出了一种基于仿射变换的奇异积分自适应单元细分法,用于解决边界积分方程中的奇异性问题。其基本思想是通过仿射变换对单元进行特征分区,并结合自适应二叉树细分技术生成高质量的积分单元。利用仿射变换和特征分区技术将初始单元划分为细分区域和投影区域,不同区域的单元细分算法分别执行、计算效率高。源点附近的细分子块采用Serendipity积分单元构建,其余积分单元则采用传统积分方法进行计算。与传统单元细分方法相比,该方法具有自适应细分、积分精度高、易于实现等优点。数值算例验证了该文方法具有良好的准确性、鲁棒性和可行性。

随机利率与非仿射跳扩散模型下的欧式期权定价

研究了具有随机利率和泊松跳的非仿射随机波动率模型下的欧式期权定价问题.首先,运用扰动法去逼近标的对数资产价格的特征函数,并得到近似的解析式;然后,运用快速Fourier变换等方法推导出欧式期权的定价公式;其次,运用数值计算比较随机利率、固定利率以及非仿射波动率过程分别对欧式看涨期权价格的不同作用,以及分析模型中利率的波动率参数和仿射结构参数对期权价格的影响.结果表明,二者对期权价格结果的影响均是正向的,且非仿射随机波动率模型比仿射随机波动率模型具有更高的灵活性.

New mutational trends in the HA protein of 2009 H1N1 pandemic influenza virus from May 2010 to February 2011

As we enter the year of 2011, the 2009 H1N1 pandemic influenza virus is in the news again. At least 20 people have died of this virus in China since the beginning of 2011 and it is now the predominant flu strain in the country. Although this novel virus was quite stable during its run in the flu season of 2009-2010, a genetic variant of this virus was found in Singapore in early 2010, and then in Australia and New Zealand during their 2010 winter influenza season. Several critical mutations in the HA protein of this variant were uncovered in the strains collected from January 2010 to April 2010. Moreover, a structural homology model of HA from the A/Brisbane/10/2010(H1N1) strain was made based on the structure of A/California/04/2009 (H1N1). The purpose of this study was to investigate mutations in the HA protein of 2009 H1N1 from sequence data collected worldwide from May 2010 to February 2011. A fundamental problem in bioinformatics and biology is to find the similar gene sequences for a given gene sequence of interest. Here we proposed the inverse problem, i.e., finding the exemplars from a group of related gene sequences. With a clustering algorithm affinity propagation, six exemplars of the HA sequences were identified to represent six clusters. One of the clusters contained strain A/Brisbane/12/2010(H1N1) that only differed from A/Brisbane/10/2010 in the HA sequence at position 449. Based on the sequence identity of the six exemplars, nine mutations in HA were located that could be used to distinguish these six clusters. Finally, we discovered the change of correlation patterns for the HA and NA of 2009 H1N1 as a result of the HA receptor binding specificity switch, revealing the balanced interplay between these two surface proteins of the virus.

Lattice Boltzmann simulation of solute transport in a single rough fracture

In this study, the lattice Boltzmann method （LBM） was used to simulate the solute transport in a single rough fracture. The self-affine rough fracture wall was generated with the successive random addition method. The ability of the developed LBM to simulate the solute transport was validated by Taylor dispersion. The effect of fluid velocity on the solute transport in a single rough fracture was investigated using the LBM. The breakthrough curves （BTCs） for continuous injection sources in rough fractures were analyzed and discussed with different Reynolds numbers （Re）. The results show that the rough frac~＇e wall leads to a large fluid velocity gradient across the aperture. Consequently, there is a broad distribution of the immobile region along the rough fracture wall. This distribution of the immobile region is very sensitive to the Re and fracture geometry, and the immobile region is enlarged with the increase of Re and roughness. The concentration of the solute front in the mobile region increases with the Re. Furthermore, the Re and roughness have significant effects on BTCs, and the slow solute molecule exchange between the mobile and immobile regions results in a long breakthrough tail for the rough fracture. This study also demonstrates that the developed LBM can be effective in studying the solute transport in a rough fracture.

An Iterative Relaxation Approach to the Solution of the Hamilton-Jacobi-Bellman-Isaacs Equation in Nonlinear Optimal Control

In this paper, we propose an iterative relaxation method for solving the Hamilton-Jacobi-Bellman-Isaacs equation(HJBIE) arising in deterministic optimal control of affine nonlinear systems. Local convergence of the method is established under fairly mild assumptions, and examples are solved to demonstrate the effectiveness of the method. An extension of the approach to Lyapunov equations is also discussed. The preliminary results presented are promising, and it is hoped that the approach will ultimately develop into an efficient computational tool for solving the HJBIEs.

Characterization and biological activities of lectin isolated from <i>Pinellia ternata</i>

In this paper, Pinellia ternata lectin (PTL) purified from 95% saturated ammonium sulfate precipitation by applying mannose-Sepharose 4B affinity column chromatography was first described. The mannose-Sepharose 4B affinity adsorption gel has already been designed and prepared before the experiments according the combinative characterization between lectin and mannose. Mass spectrometry analysis result shows that PTL is a glycoprotein with the molecular weight of 12.165 kD. It was conclude that PTL had strong agglutination effects on mouse red blood cells, and the minimum reaction concentration was 25 μg/ml according the Hemagglutination. Results of automatic amino acid analysis indicated that PTL mainly contained 15 varieties of amino acids, of which the minimum content was cysteine and aspartate was the maximum. Cell experiment results suggested that PTL of low concentrations (0.004 mg/ml, 0.02 mg/ml and 0.1 mg/ml) promoted HeLa cell proliferation, but the effect weakened with the concentrations and treated-time increasing. However, the HeLa cells pro- liferation was intensively inhibited by higher PTL concentrations (0.5 mg/ml and 1 mg/ml), and the effect increased in a dose and time dependent manner.

Affine particle-in-cell method for two-phase liquid simulation

Background The interaction of gas and liquid can produce many interesting phenomena,such as bubbles rising from the bottom of the liquid.The simulation of two-phase fluids is a challenging topic in computer graphics.To animate the interaction of a gas and liquid,MultiFLIP samples the two types of particles,and a Euler grid is used to track the interface of the liquid and gas.However,MultiFLIP uses the fluid implicit particle(FLIP)method to interpolate the velocities of particles into the Euler grid,which suffer from additional noise and instability.Methods To solve the problem caused by fluid implicit particles(FLIP),we present a novel velocity transport technique for two individual particles based on the affine particle-in-cell(APIC)method.First,we design a weighed coupling method for interpolating the velocities of liquid and gas particles to the Euler grid such that we can apply the APIC method to the simulation of a two-phase fluid.Second,we introduce a narrowband method to our system because MultiFLIP is a time-consuming approach owing to the large number of particles.Results Experiments show that our method is well integrated with the APIC method and provides a visually credible two-phase fluid animation.Conclusions The proposed method can successfully handle the simulation of a two phase fluid.

Self-Affine Fractals and the Fractal Dimension of Fractured Rock Profiles

The measured profiles of laboratory fractured rocks should be self-affine fractal.The scaling properties of these profiles are described by two parameters-the fractal dimension D and the crossover length tc The D values of eight profiles are calculated by the ruler method and by the standard deviation method respectively.It is shown that if tc is far greater than the sampling step tc two methods yield the same results,although if it is far smaller than r,the D by the standard method will be about 1.20,while D by the ruler method will very close to 1.0,because two fractal dimensions,local and global,exist on two sides of tc In order to obtain the local fractal dimension which may be close to that of the standard deviation method,the ruler method must be modified.We propose a way to estimate the tc and to modify the ruler method.Finally,a profile having given D is generated in terms of the principle of non-integer order differential,through which the above two methods are verified and lead to the same

不同级别胶质瘤患者MEK、ERK、CHKα蛋白的阳性表达情况及临床意义

目的探讨不同级别胶质瘤患者胆碱激酶α(CHKα)、细胞外信号调节激酶(ERK)及丝裂原激活蛋白激酶(MEK)蛋白的阳性表达情况及临床意义。方法回顾性分析2019年1月至2022年12月长沙市第四医院神经外科收治的124例胶质瘤患者的临床资料。检测、统计不同级别胶质瘤患者MEK、ERK、CHKα蛋白的阳性表达情况。结果不同肿瘤最大径、年龄、WHO分级及预后胶质瘤患者MEK、ERE、CHKα蛋白的高、低表达情况比较,差异均有统计学意义(P<0.05)。Ⅰ、Ⅱ、Ⅲ、Ⅳ级胶质瘤患者MEK蛋白阳性表达率分别为9.62%、7.69%、94.08%和92.04%,ERK蛋白阳性表达率分别为9.57%、7.49%、94.52%和92.18%,CHKα蛋白阳性表达率分别为9.60%、7.53%、94.71%和92.23%,高、低级别胶质瘤患者MEK、ERK、CHKα蛋白阳性表达率比较,差异均有统计学意义(P<0.05)。随访结束后结果显示,124例患者中死亡52例,失访12例,获得随访112例,随访率为90.32%。结论不同级别胶质瘤患者MEK、ERK、CHKα蛋白的阳性表达情况有明显区别,并且与患者的疾病预后明显相关,对疾病的诊断和预后判断具有重要价值。

核酸适配体筛选中单链DNA制备方法的研究进展

核酸适配体是人工合成的短链核酸,作为分子识别元件,能够与各类靶标物质高特异性、高亲和力的结合,分为单链DNA和RNA两种类型。其中单链DNA适配体由于其稳定性比RNA适配体更好而更受欢迎,因此得到广泛应用。核酸适配体筛选通常是通过配体指数富集系统进化技术(systematic evolution of ligands by exponential enrichment,SELEX)实现的,筛选能否成功在很大程度上取决于其最关键的单链制备步骤,即将双链DNA转化为相应的单链DNA。目前,存在许多方法可以制备单链DNA,包括热变性法、生物素-链霉亲和素亲和分离法、变性胶电泳分离法、核酸外切酶消化法、不对称聚合酶链式反应(polymerase chain reaction,PCR)法等。本文在总结文献报道的基础上,具体阐述了各种单链DNA制备方法的原理、优缺点及近5年的应用情况,并对这些单链DNA制备方法进行了比较和展望,以期能为成功筛选各类靶标的核酸适配体提供参考。

基于点估计仿射可调鲁棒优化的含储能电力系统实时调度

为应对大规模风电的接入,建立一种机组与储能联合参与自动发电控制的电力系统实时调度模型,并提出一种点估计仿射可调鲁棒优化来处理风电不确定性。不同于传统仿射可调鲁棒调度优化基准运行成本,点估计仿射可调鲁棒调度优化期望运行成本以提高系统经济性。提出利用确定性的点估计法来实现对期望运行成本的快速、精确评估。所提模型为一混合整数双线性约束问题,采用一种“预估-矫正”的凸化方法来求解该难题,预估阶段对储能的状态变量进行松弛,而矫正阶段直接对其状态变量进行矫正。最后,引入一种凸函数差优化进一步凸化2个阶段的双线性约束问题,以提高含储能实时调度的求解质量。在IEEE39、118以及300节点3个系统的仿真验证了所提模型及方法的有效性。

基于老年用户心智模型的日常健康管理APP 设计研究

本研究通过分析现有健康管理平台在适老化与包容性设计上的不足,结合用户体验要素,提取其中的弱势因素。以日常健康管理为核心,从“执行”与“评估”行为维度出发,结合“本能”“决策”与“情感”心智活动层级,全面收集老年用户的心智信息。采用亲和图法聚类访谈内容,构建老年用户心智模型,并提出“老有所依”App的设计理念与实践。通过眼动实验及问卷调研验证,“老有所依”App在可用性与满意度方面表现出较高指数,从而证实了设计创新点的有效性。研究表明,结合用户行为与心智活动层级获取老年心智信息,有助于提升App的适老化与包容性。本研究不仅丰富了移动健康管理领域的设计理论,也为未来相关研究提供了参考。

含碳三原子分子结构与电子亲和能的计算

本文分别采用单、双和微扰处理三激发耦合簇方法与自旋非限制的开壳层耦合簇方法对CO_(2),OCS,CS_(2)及其对应阴离子CO_(2)^(-),OCS^(-),CS_(2)^(-)进行高精度的从头算研究.我们计算了这些分子在一系列相关一致基组aug-cc-pV(X+d)Z (X=T,Q,5)以及完全基组极限下的基态平衡几何结构,并研究了芯-价电子相关与标量相对论效应的影响,计算结果与已有文献报道结果吻合较好.基于计算的几何结构,获得了中性分子CO_(2),OCS,CS_(2)的绝热电子亲和能,系统考察了不同基组以及零点能修正对这些分子电子亲和能的影响,给出了考虑各种修正下3种分子准确的电子亲和能.本文将丰富含碳三原子分子的光谱常数和电子亲和能等分子参数的信息,可为实验光谱研究提供重要参考.

基于离散元的颗粒材料中应变局部化形成与演化研究

岩土颗粒材料的应变局部化失效问题广泛存在于工程设计应用中,主要表现为介观尺度上的应变局部化现象和宏观尺度上的剪切带产生,目前在微观尺度上的形成机理尚不明确。为了系统研究颗粒集合体的应变局部化的形成与演化过程,通过使用离散单元法(Discrete Element Method,DEM)模拟了指定平面应变加载路径的真三轴试验,获取了宏观和微观尺度上的颗粒材料几何、运动以及力学信息。为了找出表征应变局部化特性的最佳特征量,比较了颗粒温度、波动位移和局部剪胀角等微观指标,发现波动位移在表征应变局部化方面与其他参数相比相关性更好,并选定其作为应变局部化表征变量。为了量化颗粒集合体从应变局部化开始产生到发育完成的具体应变区间,采用莫兰指数对波动位移的空间分布特征进行统计和分析,确定了颗粒集合体在弹塑性转换阶段的发育区间。进一步对颗粒集合体应变局部化发育区间内的波动位移空间分布进行探究,并统计不同空间区域内波动位移的概率密度函数,发现研究区域外部的局部塑性在过渡阶段停止演化,而内部塑性以逾渗模式发展。最终,通过波动位移的空间分布进行聚类分析,获得了描述介观尺度上应变局部化的团簇体模型。该模型可以将颗粒集合体宏观剪切带的形成与发育和单个颗粒的微观塑性发展相联系,刻画颗粒集合体从介观尺度上的应变局部化出现到宏观尺度上剪切带完全形成的演化过程。