Adaptive multi-mode switching strategy for the spherical underwater robot with hybrid thrusters

The conventional autonomous cruise and tracking system cannot transition and change its motion mode according to the underwater environment during operation, so it is of great significance to study the multi-mode switching of cruise control for Autonomous Underwater Vehicles (AUVs). In this paper, a Multi-Mode Adaptive Switching (MMAS) strategy for the Spherical Underwater Robot with Hybrid Thruster (HPSUR) was proposed, which provided the possibility for the robot to choose optimal control mode according to the unpredictable operating environment. Then, the dynamic and force of the hybrid thruster are analyzed to improve the accuracy of multi-mode switching, and the MMAS strategy is developed linking the attitude adjustment and switching problems. Furthermore, a series of multi-mode switching experiments were conducted using water-jet mode, propeller mode and hybrid mode. Finally, the experimental result was discussed, which verified the effectiveness and accuracy of the proposed MMAS strategy. The proposed control strategy has a certain reference value for the multi-mode switching of propulsion devices.     

Coordinated scheduling of production and logistics for large-scale closed-loop manufacturing using Benders decomposition optimization

This paper studies coordinated scheduling of production and logistics for a large-scale closed-loop manufacturing system by integrating its manufacturing and recycling process. In addition to the forward manufacturing process, different recycling units in reverse recycling process are also studied. A decentralized network is designed to formulate the coordinated scheduling problem as a mixed integer programming model with both binary and integer variables. As the problem for closed-loop manufacturing is large-scale and computational-consuming in nature, the model is divided into integer variable sub-models and complex binary variable sub-models for preprocessing and reprocessing respectively. An iterative solution approach by Benders decomposition is developed to accelerate the solving efficiency in large-scale case by updating custom constraints. A case study is conducted to investigate the managerial implications of the decentralized network for the closed-loop manufacturing system. Computational experiments demonstrate the validity and efficiency of the proposed iterative solution approach for the large-scale scenarios.     

基于MATLAB的同步发电机PSS与励磁系统仿真

在分析同步发电机励磁控制系统模型的基础上,研究了以电力系统稳定器（Power System Stabilizer—PSS）为辅助控制的同步发电机励磁控制方式,并基于MATLAB／SIMULINK构建了包含PSS的励磁控制系统的仿真模型。根据仿真结果分析在电力系统出现不同故障（三线短路以及断线故障）情况下带有PSS的励磁控制系统的控制性能,并与不加载PSS的励磁系统进行了比较,得到了在同步机励磁系统中加载PSS的必要性,为励磁系统的设计提供了依据。     

基于离散随机技术的Madaline敏感性近似计算研究

本文系统地讨论了离散型前向神经网络Madaline的输出对网络参数扰动的敏感性计算.首先,根据神经元Adaline的离散特性,提出了一种离散随机技术方法,推导了Adaline敏感性近似计算公式.该方法从理论上解决了已有的连续随机技术方法无法处理的情况,取消了过强的限制条件,并使得从理论上对Adaline敏感性近似计算进...     

A node-based smoothed finite element method (NS-FEM) for upper bound solution to visco-elastoplastic analyses of solids using triangular and tetrahedral meshes

A node-based smoothed finite element method (NS-FEM) was recently proposed for the solid mechanics problems. In the NS-FEM, the system stiffness matrix is computed using the smoothed strains over the smoothing domains associated with nodes of element mesh. In this paper, the NS-FEM is further extended to more complicated visco-elastoplastic analyses of 2D and 3D solids using triangular and tetrahedral meshes, respectively. The material behavior includes perfect visco-elastoplasticity and visco-elastoplasticity with isotropic hardening and linear kinematic hardening. A dual formulation for the NS-FEM with displacements and stresses as the main variables is performed. The von-Mises yield function and the Prandtl–Reuss flow rule are used. In the numerical procedure, however, the stress variables are eliminated and the problem becomes only displacement-dependent. The numerical results show that the NS-FEM has higher computational cost than the FEM. However the NS-FEM is much more accurate than the FEM, and hence the NS-FEM is more efficient than the FEM. It is also observed from the numerical results that the NS-FEM possesses the upper bound property which is very meaningful for the visco-elastoplastic analyses which almost have not got the analytical solutions. This suggests that we can use two models, NS-FEM and FEM, to bound the solution, and can even estimate the global relative error of numerical solutions.     

基于ARM7的油罐区测控系统的研究与设计

针对油罐区测控系统实时动态监控的需要,介绍了一种基于ARM7嵌入式微处理器的油罐区测控系统。以LPC2119为核心,采用罐区分布式结构,并用压力变送器和温度传感器分别对油罐的液位和温度进行实时在线检测和控制。软件设计中移植了μC/OS-Ⅱ操作系统,采用多任务设计方法,缩短了软件的开发进程,并有效地将LPC2119强大的管理功能和CAN总线的优点结合起来,使得通信部分能有效地将数据发送到上位机。该系统已应用于作业现场,运行可靠,取得良好的效果。     

Note on “The induced continuous ordered weighted geometric operators and their application in group decision making”

In this short communication, we will show that the condition of the theorem does not hold in general cases in a recent paper “The induced continuous ordered weighted geometric operators and their application in group decision making” [Computers & Industrial Engineering 56 (2009) 1545–1552] by Wu et al., and also illustrate an example to show that we cannot construct a consistent interval multiplicative preference relation according to the condition of theorem in general case. Furthermore, we present a more reasonable condition to satisfy Theorem 1 so that we can construct a consistent interval multiplicative preference relation.     

Uncertainty propagation in puff-based dispersion models using polynomial chaos

Atmospheric dispersion is a complex nonlinear physical process with numerous uncertainties in model parameters, inputs, source parameters, initial and boundary conditions. Accurate propagation of these uncertainties through the dispersion models is crucial for a reliable prediction of the probability distribution of the states and assessment of risk. A simple three-dimensional Gaussian puff-based dispersion model is used as a test case to study the effect of uncertainties in the model parameters and initial conditions on the output concentration. A polynomial chaos based approach is used to numerically investigate the evolution of the model output uncertainties due to initial condition and parametric uncertainties. The polynomial chaos solution is found to be an accurate approximation to ground truth, established by Monte Carlo simulation, while offering an efficient computational approach for large nonlinear systems with a relatively small number of uncertainties.     

路网数据流的预测聚集查询新方法研究

时空数据流的聚集查询技术已经成为数据库领域的研究热点。到目前为止,还没有一种有效的全时态聚集索引适用于非欧氏空间的路网数据流聚集查询。实现路网数据流的全时态聚集查询,必须解决:(1)路网的非欧氏空间特性问题;(2)路网上移动对象的重复计数、非均匀分布以及预测聚集问题。Sketch RR-tree解决了非欧氏空间特性和重复计数问题;为解决非均匀分布问题,借鉴草图划分思想,提出动态草图索引结构DynSketch:采用AMH智能划分Sketch RR-tree,使每个划分区域内车辆均匀分布,以提高聚集查询质量;同时,基于DynSketch,结合ES预测模型,提出了路网数据流的预测聚集查询算法。     

Identification of relationship between sunspots and natural runoff in the Yellow River based on discrete wavelet analysis

Annual natural runoff is an important index of a river, which may be affected by solar activities. In this study, 304 years of annual natural runoff at the Sanmenxia station located in the Yellow River and the sunspot relative number are decomposed with the application of a Complex Morlet. According to the results of real part, modulus and second power of modulus, the annual runoff series at the Sanmenxia station has an obvious periodic oscillation on 90–100, 50–80, 35–50, 15–35, about 10, and less than 10-year scales. Also, there are obvious periodic variability with 60–90 years, 30–50 years and about 10 years. There are two centers of energy: one is about 1840–1850 on 7–11-year scale and the other is about 1825–1925 on 60–70-year scale. From the wavelet variance, 3, 26, 46, 68 year periods are detected within a 100-year scale, and the 68-year period is the most significant. Similar analyses are conducted for the sunspot relative number within the same period 1700–2003. The sunspot series shows 11- and 60-year period variation, as well as eight energy centers. Then, the correlation analyses for 11- and 60-year serial scales are computed. From a long-term period (1700–2003) view, there is no notable correlation between the natural runoff and the sunspot relative number; however, it is evident that the correlations exist within a short-term period. The results also indicate that the relationships between solar activities and the natural runoff in the Yellow River are complicated.