线性切换系统的采样数据输出调节问题

本文基于采样控制,解决了线性切换系统的输出调节问题.首先考虑了外部输入信号是常数的情况,给出了采样周期与平均驻留时间的关系.通过构造一类Lyapunov-Krasovskii泛函,使得闭环系统内部稳定且调节输出趋于零.其次考虑了外部输入信号是导数有界且时变的情况,给出了采样数据状态反馈控制器,并依据采样周期和平均驻留时间关系给出的切换条件得到了切换系统实用输出调节问题可解的充分条件.最后通过两个数值例子验证了方法的有效性.     

基于改进差分进化的稀土萃取能效分离系数优化

基于机理模型的稀土萃取工艺流程没有考虑萃取槽中搅拌机的能效,导致求解得到的各级组分含量与工业实际生产数据有较大误差.通过引入能效分离系数概念,建立符合实际萃取工艺的各萃取槽稀土元素组分含量模型,构建求解能效分离系数的优化目标函数.针对该优化目标函数多峰、多变量的特点,提出一种种群规模线性减小的混沌双变异自适应差分进化改进算法(LCTADE).首先,将混沌序列嵌入改进算法中生成初始种群,增强种群多样性;其次,针对进化不同阶段对突变策略性能要求不同,提出基于DE/current-to-pbest/1和DE/rand/1的双变异策略方法;最后,采用参数自适应方法分别设置F、CR及NP值.在仿真实验中,将所提出的LCTADE方法针对CEC 2017的函数进行测试并与其他算法比较,显示出其优越性,并通过求解基于能效分离系数的稀土萃取工艺流程优化目标函数,表明所提出方法的有效性.     

Exploring the tidal effect of urban business district with large-scale human mobility data

Business districts are urban areas that have various functions for gathering people, such as work, consumption, leisure and entertainment. Due to the dynamic nature of business activities, there exists significant tidal effect on the boundary and functionality of business districts. Indeed, effectively analyzing the tidal patterns of business districts can benefit the economic and social development of a city. However, with the implicit and complex nature of business district evolution, it is non-trivial for existing works to support the fine-grained and timely analysis on the tidal effect of business districts. To this end, we propose a data-driven and multi-dimensional framework for dynamic business district analysis. Specifically, we use the large-scale human trajectory data in urban areas to dynamically detect and forecast the boundary changes of business districts in different time periods. Then, we detect and forecast the functional changes in business districts. Experimental results on real-world trajectory data clearly demonstrate the effectiveness of our framework on detecting and predicting the boundary and functionality change of business districts. Moreover, the analysis on practical business districts shows that our method can discover meaningful patterns and provide interesting insights into the dynamics of business districts. For example, the major functions of business districts will significantly change in different time periods in a day and the rate and magnitude of boundaries varies with the functional distribution of business districts.     

植入式脑机接口技术向医疗器械转化的问题与挑战

该文回顾了过去几十年脑机接口技术取得的成果,以及脑机接口科研成果向临床医疗器械转化过程中,将会面临的挑战。对此,该文首先介绍了脑机接口技术常用的信号源,包括脑电图、皮层电图和皮层内电信号及其特点;其次叙述了对商用脑机接口产品的解码能力和信息双向闭环的考量,讨论了目前脑机接口商用机设计中存在的稳定性、生物相容性挑战;最后阐述了植入式脑机接口向医疗器械转化过程中,产业化发展的政策、资金和技术路线的协同发展问题。     

Point cloud completion via structured feature maps using a feedback network

Computational Visual Media - In this paper, we tackle the challenging problem of point cloud completion from the perspective of feature learning. Our key observation is that to recover the...     

考虑风险管理的电力市场多时段均衡分析方法

均衡分析方法是电力市场运行效率分析及机制设计论证的有力工具,而如何计及差价合同和市场主体风险偏好的影响,以及高效求解多时段均衡模型,已成为使电力市场均衡分析方法实用化亟待解决的问题。从差价合同的确定、考虑风险偏好的电力市场均衡建模、基于多智能体深度强化学习的求解等方面,提出了考虑风险管理的电力市场多时段均衡分析方法。在模型框架方面,分别针对市场化差价合同和政府授权差价合同,提出了基于市场均衡结果合理确定合同价格及其曲线的方法;采用条件风险价值评估市场风险,并建立了发电商报价决策的随机优化模型;结合前瞻性安全约束机组组合和经济调度模型建立了现货市场出清模型,以保证结果的合理性。在求解算法方面,通过改进深度强化学习方法,提出了基于风险管理的多智能体深度强化学习算法,并对模型进行迭代求解。最后,通过算例验证了均衡分析方法的合理性和有效性,并剖析了不同比例市场化差价合同或政府授权差价合同,以及不同风险偏好对市场均衡的影响。     

Harmonic control of a dual-valve hydraulic servo system with dynamically allocated flows

Modern industries face increasing demands to improve the precision and workability of equipment, leading to stringent requirements for hydraulic servo systems in terms of flow, accuracy, and output power. High-flow servo valves and multi-valve synchronous control methods have seen more applications in the industry to meet these demands. However, high-flow servo valves are expensive and have unsatisfactory performance, and synchronous control methods require servo valves to have the same hydraulic characteristics, resulting in higher cost and lower accuracy of high-flow hydraulic servo systems. Also, very little has been conducted on controlling single actuators using multiple valves. In this study, we design a novel dual-valve hydraulic servo system structure with a high-flow proportional directional valve that is connected in parallel with a low-flow servo valve and further develop the mathematical model of this dual-valve system. Next, a harmonic control scheme was proposed, which included a flow allocation layer and trajectory tracking layer. Thereby, we achieved optimal control of two valves, and robust performance was guaranteed. Finally, we investigate the relationships between the flows of two valves, the deadband of the proportional directional valve, and trajectory tracking errors. Experimental results show that the proposed control scheme can effectively adjust the output flow of each valve dynamically according to the tracking trajectory and the hydraulic characteristics of the two valves, and the tracking performance of the servo system is significantly improved. This method is promised to enable the realization of an economical, high-flow, high-precision hydraulic servo system that can be generally used in various fields, such as marine engineering and construction.     

基于模拟退火的动态缆线型优化北大核心CSCD

动态电缆在水中的线型对确保电缆的合理受力,保证疲劳寿命具有重要的作用。文中针对浮式风电动态缆的陡波线型,基于经典悬链线方程,以远位张力与近位曲率的利用率之和作为线型优化的目标,采用模拟退火算法对线型进行优化,分析了不同浮力系数对线型优化的影响。文中结论对线型工程设计具有一定参考和指导意义。     

海战场态势生成技术发展综述

未来的战争必将是多兵种、多域联合作战,战场态势作为未来联合作战的重要支撑,旨在为联合作战提供精准、高效的统一态势图,而如何将多平台、同/异构传感器信息及其他情报信息与战场环境融合生成准确可靠的战场态势是亟需解决的技术难题。鉴于现代海战场对高精度、强实时、全要素战场态势图的迫切需求,对海战场态势生成技术进行了综述。首先梳理了海上态势生成项目的发展历程及能力水平;然后详细介绍了通用作战图/通用战术图等典型项目,在态势生成部分中通过态势图的要素组成、态势生成流程及关键技术对态势生成技术进行了阐述;最后对未来海战场态势生成技术的发展趋势进行了预测,希望可以为态势生成相关研究提供参考。     

面向植被边坡的地基SAR高相干点选择

基于高相干点进行相位分析,才能有效保证地基SAR（Synthetic Aperture Radar,合成孔径雷达）形变测量的准确性。在差分干涉测量领域中,广泛使用幅度离差法,可以有效地选择出岩石、建筑物等PS（Permanent Scatterer,永久散射体）点作为高相干点,但对于植被边坡,采用该方法选择出高相干点数量较少,不利于差分干涉处理。在星载SAR领域,普遍采用StaMPS方法解决植被边坡的高相干点选择问题。本文探索了StaMPS方法在地基SAR领域的适用性,提出采用非PS点来计算相干系数门限,并引入DS（Distributed Scatterer,分布式散射体）选择技术,进一步提高了高相干点的数量。对一处植被边坡的实验结果表明,相比于幅度离差法和StaMPS方法,改进方法在提高高相干点数量的同时,有效保证了其相位质量。