沙颍河流域水资源利用量与经济发展匹配特征

根据沙颍河流域河南段情况确定各地市水资源可利用量,基于数列的匹配度计算方法,对流域内10个地市2014—2018年水资源利用量与经济发展关系进行研究,分析各地市用水量、水资源可利用量与GDP关联程度。结果表明：由于气候条件等因素差异,水资源可利用量差距较大,其中漯河市和周口市单位面积水资源可利用量较多;在研究年限内,各地市水资源可利用量与用水量匹配情况差异较大;在时间维度上,各地市用水量与GDP匹配程度较好,而在空间维度上,开封市匹配情况最差,漯河等城市较好;各地市水资源可利用量与GDP匹配情况存在明显的时空差异。     

Unsupervised Scale-Consistent Depth Learning from Video

International Journal of Computer Vision - We propose a monocular depth estimation method SC-Depth, which requires only unlabelled videos for training and enables the scale-consistent...     

Identifying epidemic spreading dynamics of COVID-19 by pseudocoevolutionary simulated annealing optimizers

Neural Computing and Applications - At the end of 2019, a new coronavirus (COVID-19) epidemic has triggered global public health concern. Here, a model integrating the daily intercity migration...     

VPX总线标准研究及其在无人机中的应用展望

军用无人机以其低成本高效能、体积小隐身性能强、零伤亡等优势,被广泛应用于作战的各个阶段;但随着军事职能的拓展,传统无人机已无法满足在超恶劣战场环境下,完成多任务、分布式数据处理和大容量数据传输的要求,迫切需要一种新的、基于高性能传输总线的、支持多任务处理的无人机设备;VPX标准作为VME标准的升级版本,在国外无人机领域已有所应用;作为新一代军用加固总线产品,它满足串行、千兆高速数据率,支持PowerPC架构且扩展灵活,以其搭建无人机系统,完全可以满足现在乃至未来的需求;通过对无人机未来发展趋势及相关技术驱动因素分析,详细介绍了VPX及其后续OPENVPX标准,将其与之前版本总线进行比较,认为其在无人机系统各领域具有广泛的应用前景,最后给出一种基于VPX总线的无人机系统模型。     

基于改进扩展关联模型的飞机组件测试性研究

多信号流图模型是一种简单而有效的系统建模方法,已广泛地应用于测试性分析和故障诊断领域;为了减少飞机维修过程中组件的不必要更换,提高维修效率,对多信号流图模型的建模方法进行研究,以飞机音频管理组件(AMU)为例,建立多信号流图模型,构建故障一测试关联矩阵和故障一故障关联矩阵;为与实际出现的组件故障信息相匹配,对故障一故障矩阵进行改进,构建了实际故障信息一故障关联矩阵,对组件模型进行测试性分析;由实际维修经验可知,该信号模型可快速地定位故障,给出相应的维修措施,减少通常维修中采取的不必要措施,降低了人为因素的影响,大大地缩短了维修时间.     

基于自由摆的平板精确控制与激光追踪系统

以TI公司的MSP430F5438单片机为控制核心,结合步进电机和精密电位器WDD35D-4,实现了基于自由摆的平板控制与激光追踪系统。当摆杆摆角为45°～60°时,平板可以承载8枚一元硬币,并在5个摆动周期内维持稳定;当摆杆摆角为30°～60°时,固定在摆杆平板上的激光笔可以在15s内找到并跟踪1.5m远处的靶心。     

Optimal tracking performance of MIMO discrete‐time systems with communication constraints

The optimal tracking problem for multiple‐input multiple‐output linear‐time‐invariant discrete‐time systems with communication constraints in the feedback path is studied in this paper. The tracking performance is measured by the energy of the error signal between the output of the plant and the reference signal. The objective is to obtain an optimal tracking performance, attainable by all possible stabilizing compensators. It is shown that the optimal tracking performance consists of two parts, one depends on the nonminimum phase zeros and zero direction of the given plant, as well as the reference input signal direction, and the other depends on the nonminimum phase zeros, unstable poles, and pole direction of the given plant, as well as the bandwidth and additive white Gaussian noise of the communication channel. It is also shown that, if the constraint of the communication channel does not exist, the optimal tracking performance reduces to the existing tracking performance of the control system without communication constraints. A typical example is given to illustrate the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimal Performance in Tracking Stochastic Signal Under Disturbance Rejection

The analysis method of optimal tracking performance is proposed for multiple‐input multiple‐output (MIMO) linear time‐invariant (LTI) systems under disturbance rejection. An H₂ criterion of the error signal between the output of the plant and the reference signal is used as a measure for the tracking performance. Spectral factorization is applied to obtain the optimal solution of the system tracking error. The explicit expressions are derived for this minimal tracking error with respect to random reference signals under disturbance rejection. It is shown that the nonminimum phase zeros, the zero direction, the unstable poles, the pole direction of a given plant, statistical characteristics of the reference input signal, and disturbance signal have a negative effect on a feedback system's ability to reduce the system error with disturbance rejection. The results show that the optimal tracking performance will further be damaged because of disturbance rejection. Some typical examples are given to illustrate the theoretical results.     

A new admissibility condition of discrete-time singular systems with time-varying delays

This paper gives a novel delay-dependent admissibility condition of discrete-time singular systems with time-varying delays. For convenience, the time-varying delay is assumed to be the sum of delay lower bound and the integral multiples of a constant delay. Specially, if the constant delay is of unit length, the delay is an interval-like time-varying delay. The proposed admissibility condition is presented and expressed in terms of linear matrix inequality (LMI) by Lyapunov approach. Generally, the uncertainty of time-varying delay would lead to conservatism. In this paper, this critical issue is tackled by accurately estimating the time-varying delay. Consequently, the proposed admissibility condition is less conservative than the existing results, which is demonstrated by a numerical example.     

保持几何特征的自适应弹性二次曲线模型

物体形状特征的准确提取往往受到图像获取、目标分割等过程中各种因素的影响,因而需要构造一种鲁棒的形状表现来保有其本质特征。揭示弹性二次曲线(EQW)模型中能量权重因子和样条重叠度因子与形状几何特性间的关系,提出一种自适应保持几何特征的EQW形状表现模型,并将该模型与交互式Live Wire算法相结合,应用至图像分割中,对于各种模态图像中的目标进行分割实验。直观上,本文方法能够在去除噪声同时较好地保持目标形状的显著特征;量化结果方面,交互式分割误差保持在较小稳定范围内,引入EQW模型带来的时间开销亦在可接受范围内。