Inspection of Remanent Polarization in the Ferroelectric Ceramic PZT 95/5 Through Pyroelectric Effect

Shock-induced depoling of the ferroelectric (FE) ceramic PZT 95/5 is utilized in a number of pulsed power devices. Nondestructive testing of remanent polarization of PZT 95/5 is developed by pyroelectric effect in this paper. Approximately linear relation between the change of polarization during low- to high-temperature rhombohedral FE phase and the remanent polarization was found through pyroelectricity of a single piece of PZT 95/5 ceramics. The change of polarization of a prototype for shock-driven pulsed power during the FE_HT↔FE_LT phase transformation was also investigated through directly measuring the pyroelectric current. Results indicate that pyroelectric effect caused by the reversible FE_HT–FE_LT phase transition could be used as a non-destructive inspection for the remanent polarization of a prototype about shock-driven pulsed power supply.     

一种基于CloudStack的企业级云资源平台网络优化研究

在对云资源平台的现状进行分析后,提出了一种基于Cloud Stack的企业级云资源平台网络优化方案,通过与现有3种解决方案进行对比,展示了该方案的可靠性和有效性。同时,针对可能存在的风险和不足进行了充分的考虑和论证,并给出了应对措施。     

基于安全隔离的边界防护体系的设计与实现

本文针对电子政务信息系统的特点,设计了基于安全隔离的边界防护体系。将安全隔离技术应用到电子政务中,实现了数据的安全高效实时传输,形成了多方位的安全边界防护体系架构。     

分析计算思维与计算机方法

计算机思维与计算机方法论都有着自己的特点,可相互促进并互补。例如,计算机思维可以为计算机方法论提供参考依据,同时通过计算机方法论的学习、研究,更更好培养出计算机思维。两者各具优势,是值得相互学习的。本文分析了计算思维与方法论的相关概念,同时对两者关系进行简单阐述。     

畜禽精确饲喂控制系统的研究与实施

基于Win CE 6.0平台,开发一套精确饲喂控制系统实现对畜禽的精确饲喂。以每个舍为单元,采用实时监控管理形式。使用耳标对猪进行身份识别。通过人工智能和畜禽养殖专家的知识库,自动计算,鉴别不同时期的畜禽,以此给予不同的喂食量,不同的饲料。系统主要有识别模块,实时监测模块,数据处理模块,人工控制模块,系统参数设定模块等组成。系统较智能化,易操作,可靠性强,易升级,可辅助畜禽养殖场,实现优质高产高效的养殖目的。     

压缩感知算法在阵列测向中的相干信号分辨

现有算法在进行信号重建时,需要原始信号的稀疏信息来控制初始原子集的大小和算法迭代的最大次数,这削弱了重建精度,增加了计算复杂度,限制了其实际应用能力。为了克服这个问题,提出了基于正交匹配追踪算法的改进算法。该算法将阵元个数作为假设稀疏度,在稀疏度未知的初始阶段扩展初始原子集。最后通过对测量信号的幅度进行阈值过滤以实现信号的分辨和信源数的估计。为解决测向人员面对监测软件所指示的多个信号示向度中,无法分辨哪些指示方向是同一个信号源所产生的折反射信号的问题,首次提出了基于压缩感知算法的相干关系分析和相干信号分辨的模型。实测数据结果表明,该算法在不同环境下可以清晰分辨相干信号,并且能够适应多种实验平台。     

基于多通道分离整合的多尺度单幅图像去雨算法

由于密度不同的雨对图像造成的遮挡不同,图像去雨一直都是一项极具挑战性的任务。目前,基于深度学习的图像去雨算法已经成为主流。然而,多数深度学习的架构都是通过堆叠卷积层来设计的,执行去雨任务后图像仍存在着大小不一的雨痕,这些方法并不能很好地关注训练中雨图的局部信息和上下文信息。为了解决上述问题,本文设计一种基于多通道分离整合的卷积神经网络用于图像去雨。第一步通过通道分离,再利用卷积层间的层级连接,构成多尺度模块,最终将不同通道的输出进行整合。该模块可以增大感受野,探索特征图之间的空间信息,更好地提取特征。第二步利用渐进网络来反复计算挖掘上下文信息,能够很好关联到全局特征。整体模型易于实施,可以端对端训练。在常用的数据集以及自建的自动驾驶雨天数据集上的大量实验表明,本文方法比现有方法取得了明显的改进。     

New Robust Stability Criteria for Lur’e Systems with Time-varying Delays and Sector-bounded Nonlinearities

This paper deals with a robust stability problem for uncertain Lur’e systems with time-varying delays and sector-bounded nonlinearities. An improved delay-dependent robust stability criterion is proposed via a modified Lyapunov-Krasovskii functional (LKF) approach. Firstly, a modified LKF consisting of delay-dependent matrices and double-integral items under two delay subintervals is constructed, thereby making full use of the delay and its derivative information. Secondly, the stability criteria can be expressed as convex linear matrix inequality (LMI) via the properties of quadratic function application. Thirdly, to further reduce the conservatism of stability criteria, the quadratic generalized free-weighting matrix inequality (QGFMI) is used. Finally, some numerical examples, including the Lur’e system and the general linear time-delayed system, are presented to show the improvement of the proposed approach.

     

Unified analytical solution for deep circular tunnel with consideration of seepage pressure,grouting and lining

Journal of Central South University - A new unified analytical solution is presented for predicting the range of plastic zone and stress distributions around a deep circular tunnel in a homogeneous...     

Improved Computational Model of Grid Cells Based on Column Structure

To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian-like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real-time positioning results are modified.