交换式以太网用于现场实时通信的研究

基于网络演算理论对FCFS调度和IEEE802.1P调度的交换式以太网实时性进行了分析,根据用于过程控制和运动控制领域的工业以太网实时要求及特点对交换式以太网在工业实时性满足方面进行了具体说明.对于用于过程控制现场的工业以太网并不需要对抖动进行严格控制,实时要求没有用于离散控制工业以太网的苛刻,同时商用网络软硬件技术还在不断发展,可以探索基于交换式以太网的新技术进行过程工业实时通信以太网的构建.     

交换机在工业以太网中的应用探讨

分析传统的商用以太网用于工业现场出现的问题，以及交换机在工业以太网中的应用，提出交换机用于工业现场需要注意的问题。     

单控制器多任务网络化控制系统采样点调度研究

针对单控制器多任务的交换式以太网控制系统数据传输和控制性能优化问题,提出了传感器主动退避冲突采样时间点的调度优化方法。使用True Time2.0工具箱搭建了单控制器多任务的交换式以太网控制系统仿真平台进行仿真研究,并与未采用此方法的传统系统进行了对比。仿真结果验证了其可行性。     

使用遗传算法划分交换式工业以太网

针对交换式工业以太网的数据通信特点,采用遗传算法来寻找其网络划分问题的次优解。将网络划分问题等价为一个多目标优化问题,即一方面要减少子网间通信量,同时需要平衡各个子网的通信负荷;此外交换机物理条件的限制也为该优化问题设置了约束条件。在设计遗传算法的适应度函数和遗传算子时,充分考虑了控制网络的通信特点:如控制器的存在和现场设备通信的单向性。最后通过仿真验证了该算法的有效性。     

以太网在工业应用中的实时能力分析

以工业控制过程为背景，详细分析以太网端到端的通信延迟，给出排队延迟的期望表达式，发送延迟和传输延迟的计算方法；通过仿真，分析网络节点数目、帧的长度和通信速率对以太网实时能力的影响，并提出以太网在工业应用中改善实时能力的方法。     

基于交换式以太网的专家控制系统

介绍一种基于交换式以太网的专家控制系统 ,该系统具有简单经济、灵活可靠、易于实现、维护方便等特点 ,有利于专家控制在中小规模企业中的推广与应用。     

千兆校园网解决方案初探

本文中的千兆校园网以1000M以太网为骨干网，从用户需求的角度对交换机、服务器、网络软件和网络安全方面进行了详细的探讨和设计，使校园进入信息高速公路。     

GE最新加固型6U OpenVPX10千兆以太网交换机

GE智能平台近日宣布推出NETemity TMGBX460加固型6U OpenVPX数据面板交换机模块，这是首个针对部署国防和航空航天应用的10干兆以太网解决方案，支持10GigE处理节点之间的处理器问高吞吐量通信（IPC）。     

EDF调度方法在交换式工业以太网中的实现

针对工业以太网的数据特点 ,通过在以太网数据帧中引入IEEE80 2 .1Q优先级字段来区分周期性实时数据和非实时数据 ,并对前者优先进行传送。同时还在周期性数据帧中引入截止期限字段来区分其不同的紧急程度 ,并对其采用非中断的EDF调度方法来改善周期性数据帧的端到端延迟。最后通过仿真试验验证了该方法的可行性。     

Moxa将工业以太网交换机带入下一代10GbE连接时代

Moxa推出10GbE以太网工业核心交换机产品家族。Moxa ICS—G7000系列—ICS G7826／G7828 3层和ICS-G7526／G75282层24口千兆高端口密度以太网交换机．提供更大灵活性和扩展的电源输入和网络冗余，确保不问断系统运行。无风扇设计确保长期持久性，通过使用最多4个IOGbE以太网口．使系统高性能达到一个新的水平。     

基于观测器的网络切换模糊系统的鲁棒镇定

研究一类系统状态不可测的不确定性网络切换模糊系统的鲁棒镇定问题。考虑单包传输且没有数据包丢失的情况,建立网络切换模糊系统的离散模型,使用切换技术及多Lyapunov函数方法,设计模糊观测器及反馈控制器,并以矩阵不等式的形式给出使系统渐近稳定的条件。最后仿真结果表明方法的有效性。     

Dielectric relaxation and resistive switching of Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4 thin films with different thicknesses of the Bi0.96Sr0.04Fe0.98Co0.02O3 layer

Bi_0.96Sr_0.04Fe_0.98Co_0.02O₃/CoFe₂O₄(BSFCO/CFO) bilayered thin films with different thicknesses of the BSFCO layer are synthesized on FTO/glass substrates by chemical solution deposition method (CSD). The influence of BSFCO thickness on the microstructure, dielectric relaxation, ferroelectric properties and resistive switching (RS) of the thin films are researched. Strain exists in the prepared thin films and gives rise to structural distortion, which has an effect on charged defects and ferroelectric polarization. Dielectric relaxation that is closely related to the interfacial polarization at the BSFCO/CFO interface is observed, and the dielectric loss peaks along with decreasing intensity shift to high frequency with decreasing strain. The Maxwell-Wagner two-layer model is adopted to investigate the mechanism of dielectric relaxation, and the relaxation time τ is calculated and it shown to be directly proportional to the strain. It is found that the dielectric properties, including low dielectric loss, can be improved by controlling the BSFCO layer thickness. The ferroelectric properties improve with the decreasing strain, the 12-BSFCO/CFO thin film possesses a large P_r ~ 102.9?μC/cm² at 660?kV/cm. The observed resistive switching (RS) behavior is attributed to the interfacial conduction mechanism, it is found that strain-dependent the ferroelectric polarization switching modulates the width of depletion layer and the height of potential barrier at the interface, resulting in the different resistance states.     

Carrier transport mechanism and bipolar resistive switching behavior of a nano-scale thin film TiO2 memristor

A titanium dioxide (TiO₂) based memristor device having an active layer thickness of 10?nm was fabricated using radio frequency (RF) reactive sputtering and its resistive switching characteristics and carrier transport mechanisms were investigated. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to confirm the structural properties of the device. Measurement of the time-dependent current-voltage (I-V-t) was used to characterize resistive switching and memristive behavior. The characteristic pinched hysteresis I-V loops of the memristor were apparent. Bipolar and homogeneous resistive switching characteristics and a forming voltage of 2?V were detected in the device. The retention time exceeded 10³ s and the endurance test was reasonably acceptable. In addition, the carrier transport mechanism of the device was revealed. The linear region of the low electric field demonstrated ohmic behavior, whereas the non-linear high electric field region was dominated by a Schottky emission carrier transport mechanism. A Poole-Frenkel emission mechanism acted as a secondary conduction mechanism. It was proposed that the Poole-Frenkel and Schottky emission mechanisms were associated with oxygen vacancies in the TiO₂.     

Polymer memories: Bistable electrical switching and device performance

As an emerging area in organic electronics, polymer memories have become an active research topic in recent years. Polymer memories based on bistable electrical switching are likely to be an alternative or supplementary technology to the conventional memory technology facing the problem in miniaturizing from micro- to nano-scale. In this article, an account of our recent work on bistable electrical switching in a series of processable electroactive polymers is given. The polymers can provide the required electronic properties within a single macromolecule for memory device applications. Bistable electrical switching phenomena arising from four processes, viz., trapping-detrapping, charge transfer, conformational change and nanocomposite redox effects, in electroactive polymers are described. In each case, three aspects of the memory effect, viz., (i) materials and structural features, (ii) conductance switching and current-voltage characteristics, and (iii) operating mechanism and electronic transitions are emphasized. Finally, the performance of these polymer memories is summarized.     

Resistance switching in electrodeposited polycrystalline Fe3O4 films

Resistance random access memory (RRAM) is an emerging nonvolatile memory that offers advantages of scalability, fast switching, and low voltages. Magnetite, Fe₃O₄, has been shown to exhibit resistance switching in nanoscale architectures such as superlattices. Here, we show that electrodeposited polycrystalline films of Fe₃O₄ exhibit multistate resistance switching. Experiments suggest that the insulator-to-metal transition may be facilitated by the presence of a thin nano-crystalline layer which is critical for resistance switching to occur at lower bias. We also show that the switching behavior can be tuned through the applied deposition potential. The multiple resistance states accessible in these simple architectures open up new possibilities for multi-bit data storage and retrieval.     

Transparent AlON ceramic combined with VO2 thin film for infrared and terahertz smart window

Transparent AlON ceramics are intriguing window materials with excellent mechanical strength and superb optical transparency from the near ultraviolet to the mid-infrared range. However, previous studies focused their investigations in the visible range; therefore, the application of transparent AlON ceramics to tunable windows has yet to be reported. In this work, a VO₂ thin film with a characteristic semiconductor-metal phase transition (SMT) was fabricated on a transparent AlON ceramic, which exhibited remarkable tunable switching properties in the infrared and terahertz ranges. The transparent AlON ceramic was prepared by a two-step method, which included carbothermal reduction and pressureless sintering. The resulting ceramic exhibited high transparency of over 70% in the visible-infrared range and a notable THz transmission of 64.5–73.9% at 0.1–1.5?THz. The VO₂ thin film was prepared on a transparent AlON ceramic using the sol-gel method and showed excellent optical and electric switching performance. The square resistance variance was close to four orders of magnitude, and an infrared switching ratio of over 40% was obtained. Furthermore, the combined structure showed an efficient THz switching ratio of approximately 70.9%. This study proposes a composite material combined with a transparent ceramic and a phase transition oxide and provides great insights into their application in infrared and terahertz smart windows as well as in switching devices.     

Forming-free bipolar resistive switching in nonstoichiometric ceria films

The mechanism of forming-free bipolar resistive switching in a Zr/CeO _x /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO _y layer at the Zr/CeO _x interface. X-ray diffraction studies of CeO _x films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO _x film and in the nonstoichiometric ZrO _y interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).     

基于ABPLC的玻壳成型冗余自控系统的设计

介绍基于美国AB公司PLC的玻壳成型冗余自控系统。控制技术通过软冗余方式实现,网络通信采用Profibus-DP、MPI及Ethernet方式。     

Abnormal coexistence of unipolar,bipolar, and threshold resistive switching in an Al/NiO/ITO structure

This paper reports an abnormal coexistence of different resistive switching behaviors including unipolar (URS), bipolar (BRS), and threshold switching (TRS) in an Al/NiO/indium tin oxide (ITO) structure fabricated by chemical solution deposition. The switching behaviors have been strongly dependent on compliance current (CC) and switching processes. It shows reproducible URS and BRS after electroforming with low and high CC of 1 and 3 mA, respectively, which is contrary to previous reports. Furthermore, in the case of high-forming CC, TRS is observed after several switching cycles with a low-switching CC. Analysis of current-voltage relationship demonstrates that Poole-Frenkel conduction controlled by localized traps should be responsible for the resistance switching. The unique behaviors can be dominated by Joule heating filament mechanism in the dual-oxygen reservoir structure composed of Al/NiO interfacial layer and ITO. The tunable switching properties can render it flexible for device applications.     

多层次结构模型预测控制系统的层次间模型切换方法

引言实际的工业过程对象,大部分都呈现出很强的非线性特性,其控制过程十分复杂。虽然近年来,对非线性技术的研究已经取得了很多的成果。但是非线性系统精确建模困难[1]、非线性微分方程求解