An improved kernel correlation filter for complex scenes target tracking

Multimedia Tools and Applications - Video tracking technology employed to achieve efficient and accurate tracking of targets in complex scenes has often been one of the challenges to be tackled....     

The Contributions of Climate Changes and Human Activities to Long-Term Variations in Lake Sediments Based on Results from Generalized Additive Models

Water Resources Management - Climate changes and human activities can influence lake sediments, which may lead to disruptions in aquatic environments. A better understanding of these effects is...     

电动帆改进推力模型及深空探测性能分析

电动太阳风帆(简称电动帆)是一种利用太阳风动能冲力飞行的新兴无质损飞行器.针对电动帆传统推力模型中忽略了姿态对推力幅值影响的问题,本文推导得出了一种解析形式的改进推力模型,并与最新的多项式拟合改进推力模型进行了对比.对比结果显示两种改进推力模型数值结果很接近,但本文的解析改进推力模型形式更简单.为了重新评估电动帆在深空探测中的性能,以地球至火星的飞行任务为算例,分别采用传统推力模型和解析改进推力模型进行了电动帆轨迹优化仿真.仿真结果显示,在相同特征加速度情况下,采用改进解析推力模型完成任务所需时间,大于采用传统推力模型所用时间.上述现象的原因在于传统推力模型中忽略了姿态改变对推力加速度大小的影响,并高估了电动帆所能产生的最大推进角.     

Containment Control of Fractional Order Multi-Agent Systems With Time Delays

In complex environments, many distributed multiagent systems are described with the fractional-order dynamics. In this paper, containment control of fractional-order multiagent systems with multiple leader agents are studied. Firstly, the collaborative control of fractional-order multi-agent systems (FOMAS) with multiple leaders is analyzed in a directed network without delays. Then, by using Laplace transform and frequency domain theorem, containment consensus of networked FOMAS with time delays is investigated in an undirected network, and a critical value of delays is obtained to ensure the containment consensus of FOMAS. Finally, numerical simulations are shown to verify the results.      

多样化实时刚体破碎模拟

目的 现有刚体破碎仿真模拟中,基于物理受力分析的方法往往难以应用在对实时性要求较高的场景中;而基于非物理方法的破碎模拟,破碎效果大多缺乏多样性。为了使得破碎模拟同时满足实时性和破碎效果多样化,提出了一种多样化实时刚体破碎模拟方法。方法 进行破碎模拟时首先由选定的种子点生成类型得到种子点集,采用Sweep Plane算法生成Voronoi图后基于Voronoi图信息对模型进行空间剖分;然后选择破碎时行为模拟方式,对物体破碎时所受外力进行模拟;最后对破碎时碰撞检测及碰撞后碎片的运动过程进行模拟并渲染显示。结果 通过组合不同的种子点生成类型和破碎时行为模拟方式,得到了多样化的刚体破碎效果。对单个刚体进行破碎模拟时,碎片数目不超过200个时帧率可以达到75帧/s,满足实时性的需求;对多个可破碎目标同时存在的复杂场景,破碎仿真模拟的平均帧率可以达到50帧/s,同样满足实时性要求;与现有方法对比的结果也验证了本文方法在计算效率和破碎效果多样性两方面达到了较好的平衡。结论 本文方法在满足实时性要求的同时,丰富了刚体破碎的效果,不同种子点生成类型和破碎时行为模拟方式的组合可以实现破碎效果多样性。     

A decomposition technique of generalized degrees of freedom for mixedmode crack problems

The numerical manifold method (NMM) builds up a unified framework that is used to describe continuous and discontinuous problems; it is an attractive method for simulating a cracking phenomenon. Taking into account the differences between the generalized degrees of freedom of the physical patch and nodal displacement of the element in the NMM, a decomposition technique of generalized degrees of freedom is deduced for mixed mode crack problems. An analytic expression of the energy release rate, which is caused by a virtual crack extension technique, is proposed. The necessity of using a symmetric mesh is demonstrated in detail by analysing an additional error that had previously been overlooked. Because of this necessity, the local mathematical cover refinement is further applied. Finally, four comparison tests are given to illustrate the validity and practicality of the proposed method. The aforementioned aspects are all implemented in the high‐order NMM, so this study can be regarded as the development of the virtual crack extension technique and can also be seen as a prelude to an h‐version high‐order NMM. Copyright © 2017 John Wiley & Sons, Ltd.     

Adoption of combined detection technology of tumor markers via deep learning algorithm in diagnosis and prognosis of gallbladder carcinoma

This study was to explore the application value of back propagation (BP) neural network (BPNN) and genetic algorithm (GA) in the combined detection and prognosis of tumor markers in patients with gallbladder cancer. 446 patients with gallbladder cancer were included in the experimental group, 279 patients with benign gallbladder disease were included in the control group, and 188 healthy people were selected and included in the blank group. Serum tumor markers (CA242, CA199, CEA, and CA125) of the three groups were detected by electrochemical luminescent immune analyzer, and follow-up data for 5 years after surgery were collected. Based on BPNN and GA, an optimization algorithm for multi-tumor markers was constructed and applied to the combined detection of tumor markers in patients. The artificial neural network (ANN), dynamic network biomarker (DNB), auxiliary diagnosis algorithm of the support vector machine (SVM) based on the particle swarm optimization (PSO) (PSO-SVM), matched-pairs feature selection (MPFS) based on the machine learning, and the BPNN were introduced to compare with the algorithm constructed. The diagnostic performances of the algorithms were evaluated with the fivefold cross-validation method. The results showed that the levels of CanAg (CA) 242, carcinoma embryonic antigen (CEA), CA199, and CA125 and positive rates in the experimental group were significantly higher than those in the control group and the blank group (P?<?0.05); but the differences between control group and blank group were not visible (P?>?0.05). The sensitivity (91.72%) and specificity (87.49%) in detecting CA242 and CA199 based on the proposed algorithm were the highest; the sensitivity (0.9186), specificity (0.8622), and accuracy (94.94%) of the proposed algorithm were higher than those of the conventional algorithms. The postoperative follow-up survival rate of patients in the experimental group was reduced from 41.72% in the first year to 4.28% in the fifth year; tumor node metastasis (TNM) stage IV, neck gallbladder cancer, and CA199 were significantly correlated with the survival rate of patients in the experimental group (P?<?0.05). In summary, the combined detection technology of multiple tumor markers based on deep learning algorithms showed excellent diagnostic and prognostic performance for gallbladder cancer. The occurrence of gallbladder cancer was related to the tumor markers CA242, CA199, CEA, and CA125, showing better detection effects by combination of CA242 and CA199. The TNM stage IV, neck gallbladder cancer, and CA199 were independent risk factors for the decrease in survival rate of patients with gallbladder cancer.