Modeling of LiFePO_4 battery open circuit voltage hysteresis based on recursive discrete Preisach model

This paper focuses on the modeling of LiFePO4 battery open circuit voltage(OCV) hysteresis. There exists obvious hysteresis in LiFePO4 battery OCV, which makes it complicated to model the LiFePO4 battery. In this paper, the recursive discrete Preisach model(RDPM) is applied to the modeling of LiFePO4 battery OCV hysteresis. The theory of RDPM is illustrated in detail and the RDPM on LiFePO4 battery OCV hysteresis modeling is verified in experiment. The robust of RDPM under different working conditions are also demonstrated in simulation and experiment. The simulation and experimental results show that the proposed method can significantly improve the accuracy of LiFePO4 battery OCV hysteresis modeling when the battery OCV characteristic changes, which conduces to the online state estimation of LiFePO4 battery.     

Study of beam-fanning hysteresis in photo- refractive SBN:Ce: light-induced and primary scattering as functions of polar structure

We study light-induced scattering (beam-fanning) in the photorefractive crystal SBN:Ce as a function of the polar structure of the crystal. The spatial structure of the beam-fanning is measured at different externally applied electric fields, and an optical hysteresis is found in the scattering. It is shown that the scattering hysteresis results from a polarization hysteresis typical for ferroelectrics in the polar phase. New information about primary scattering in SBN is obtained, and a corresponding model of its origin is proposed. It is shown that the intensity and angular distribution of the primary scattering strongly depend on the polar structure of the crystal and can be affected by the subsequent action of an external field and coherent illumination. Received: 27 August 2002 / Revised version: 19 December 2002 / Published online: 26 March 2003 RID="*" ID="*"Corresponding author. E-mail: mirco.imlau@uni-osnabrueck.de     

自发极化强度对VFLC电光迟滞曲线影响的电路级模拟

提出了关于V字型铁电液晶(V-shaped Ferroelectric Liquid Crystal,VFLC)的等效电路模型,旨在将EDA技术引入对VFLC光电集成系统进行研究、开发和设计。该模型考虑了由铁电液晶盒多层结构和驱动电路引起的阻抗分配效应,以及极化与非极化锚定能对VFLC光电响应特性的影响。演示了电光迟滞曲线的反常迟滞、V字型及正常迟滞状态,并着重就自发极化强度对电光迟滞曲线的影响给出了模拟结果和分析。结果表明:强制电压随驱动信号频率的提高而增加,但增加速度随自发极化强度的提高而减慢;强制电压和迟滞反转频率随自发极化强度的变化均存在一个拐点,强制电压在自发极化强度为80nC/cm2时取到最小值(-0.084V),迟滞反转频率在自发极化强度为90nC/cm2时达到最大值(6.4Hz);自发极化强度小于80nC/cm2时,迟滞反转频率随自发极化强度准线性增加。模拟结果从量级和趋势上均与实验结果吻合。     

Size effects upon phase transitions in vanadium oxide nanocomposites

A phenomenological model has been proposed for the formation of the major thermal hysteresis loop of optical parameters upon the semiconductor-metal phase transition in vanadium oxide nanocomposites. It has been demonstrated that the effects associated with the influence of nanocrystallite sizes on the phase transition temperature in an individual nanocrystallite, which is determined by the width of the elementary hysteresis loop and the position of the phase equilibrium temperature on the temperature scale, manifest themselves in the form of pronounced features in the loop shape. In particular, the size effects for VO₂ polycrystalline films are observed in the formation of a trapezoidal shape of the optical thermal hysteresis loop with a wide lower base, whereas these effects for nanocomposites based on porous glasses with VO₂ nanocrystals are revealed in the form of the optical hysteresis loop with a narrow lower base (wide upper base). The proposed model also explains the symmetric shape of the major hysteresis loop for vanadium oxide nanocomposites based on opals. The size effects in opal nanocomposites with strictly fixed sizes of pores and, therefore, nanocrystallite sizes manifest themselves in the form of well-defined steps in the heating and cooling branches of the major hysteresis loop.     

荷控忆阻器等效电路分析模型及其电路特性研究

忆阻器是物理上新实现的具有记忆特性的基本二端电路元件. 根据φ-q关系式的泰勒级数形式构建了荷控忆阻器等效电路分析模型, 以三次非线性荷控忆阻器模型为例, 对不同参数条件下的荷控忆阻器进行了伏安关系、有无源性等电路特性的理论分析. 结果表明: 荷控忆阻器的伏安关系具有斜体“8”字形紧磁滞回线特性, 随其参数符号的不同, 荷控忆阻器呈现出无源性和有源性, 导致其电路特性发生相应的变化; 相比无源荷控忆阻器, 有源荷控忆阻器更适用于作为二次谐波信号产生电路使用. 制作了荷控忆阻器特性分析等效电路的实验电路, 实验测量结果很好地验证了理论分析结果. 关键词： 荷控忆阻器 等效电路 伏安关系 电路特性     

基于有源广义忆阻的无感混沌电路研究

采用常见元器件等效实现一个广义忆阻器, 进而制作出一个电路特性可靠的非线性电路, 有助于忆阻混沌电路的非线性现象的实验展示及其所产生的混沌信号的实际工程应用. 基于忆阻二极管桥电路, 构建了一种无接地限制的、易物理实现的一阶有源广义忆阻模拟器; 由该模拟器并联电容后与RC桥式振荡器线性耦合, 实现了一种无电感元件的忆阻混沌电路; 建立了无感忆阻混沌电路的动力学模型, 开展了相应的耗散性、平衡点、稳定性和动力学行为等分析. 结果表明, 无感忆阻混沌电路在相空间中存在分布2个不稳定非零鞍焦的耗散区和包含1个不稳定原点鞍点的非耗散区; 当元件参数改变时, 无感忆阻混沌电路有着共存分岔模式和共存吸引子等非线性行为. 研制了实验电路, 该电路结构简单、易实际制作, 实验测量和数值仿真两者结果一致, 验证了理论分析的有效性.     

A Network of Analog Metal Oxide Semiconductor Circuits for Motion Detection with Local Adaptation to a Background Image

Inspired by a mechanism of biological vision systems, a model and a network of analog metal oxide semiconductor (MOS) circuits are proposed which display an optical flow with local adaptation to the relative velocity of a background image. A function of displaying an optical flow successfully worked as a result of simulations using the simulation program with integrated circuit emphasis (SPICE). A function of varying an optical flow at a certain instant by local adaptation was also demonstrated. The proposed network is suitable for the realization of a large-scale integrated circuit (LSI), which displays an optical flow with local adaptation to the local velocity of a background.     

Circuit model for analysis of SOA-based photonic switch

This paper presents an equivalent lumped element electric circuit model for traveling wave semiconductor optical amplifier (SOA) in integrated circuit applications. The model facilitates incorporation of chip and package parasitic elements of SOA. The model is used to represent an all optical 2 × 2 switch based on cross gain modulation in SOA capable of operating at an ultra fast speed. SPICE simulation of the switch with the proposed circuit model provides bit error rate (BER) values at the switch output which agrees well with the experimentally measured values at 10 Gb/s. The degradation of switching performance has been examined in terms of bit error rate, modulation bandwidth and switching time in the presence of chip parasitic elements of SOA.     

Polarization encoded all-optical quaternary successor with the help of SOA assisted Sagnac switch

The application of multi-valued (non-binary) signals can provide a considerable relief in transmission, storage and processing of large amount of information in digital signal processing. Optical multi-valued logical operation is an interesting challenge for future optical signal processing where we can expect much innovation. A novel all-optical quaternary successor (QSUC) circuit with the help of semiconductor optical amplifier (SOA)-assisted Sagnac switch is proposed and described. This circuit exploits the polarization properties of light. Different logical states are represented by different polarization state of light. Simulation result confirming described method is given in this paper. Proposed all-optical successor circuit can take an important and significant role in designing of all-optical quaternary universal inverter and modulo arithmetic unit (addition and multiplication).     

Discontinuity of mode transition and hysteresis in hydrogen inductively coupled plasma via a fluid model

A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to investigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures,by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determinative role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase(decrease) at the E to H(H to E) mode transition, indicating an improved(worsened) inductive power coupling efficiency.     

Synthesis algorithm of a multi-channel lattice-form optical delay-line circuit

A novel synthesis algorithm for multi-channel (M?2) lattice form optical delay-line circuit is presented in this paper. This circuit offers multi-port FIR optical filter with delay time of N Δτ (Δτ: unit delay time). Synthesis algorithm is based on division of total transfer matrix into unit blocks. Developed method confirms that 1×M optical delay-line circuit offers same transmission characteristics as 1×M FIR digital filter. Band-pass flat group delay type filter is considered as an example in this paper. It is also confirmed that proposed delay-line circuit can realize 100% power transmittance.     

有源-吸收分段式脊型波导半导体激光器的光双稳激射特性

本文报道了一种脊型波导有源-吸收分段结构半导体激光器中的光双稳输出特性的实验研究结果及其理论分析.给出了实验中发现的获取最大光滞回线宽度(Hysterisis)、所对应的器件结构参数以及电注入水平.此外,一种光线近似理论模型被采用来求解光输出特性从而得到了与实验近似一致的结果.     

Small and large signal analysis using circuit model of InGaAs/InP based uni-travel carrier photodiode

An equivalent circuit model of uni-traveling carrier photodiode (UTC-PD) is developed from integral carrier density rate equation and few important properties of the device such as the electrical and optical characteristics are evaluated by employing advanced device physics. Circuit model incorporates chip and package parasitic of the device quite simply to provide practical behaviour of UTC-PD. We have developed small signal ac circuit model which is useful for the analysis of low power modulation characteristics of the device and dc circuit model which is advantageous to find wavelength dependent responsivity fairly accurately. At high optical input power the device bandwidth is found to be increased through enhancement of self-induced field in the absorption region and high output power can be derived from the device when absorption width is large. Such condition calls for large signal analysis. We have developed large signal circuit model by combining few mathematical transformations with small signal circuit model with different circuit element values. Our large signal model is unique that the same circuit can be used for both small and large signal analysis. With large signal model the optical power induced bandwidth improvement and output photocurrent saturation are explained. Large signal model is validated through linearity and IP3 analysis which found close agreement with the measured results.     

A neural networks based model of inverse hysteresis

A novel and simple approach based on transformation using neural networks is proposed in this paper to model the inverse behavior of hysteresis. In this approach, a continuous transformation is used to construct an elementary inverse hysteresis operator (EIHO), which can extract the change tendency of inverse hysteresis. Then based on the EIHO, an expanded input space is constructed to transform the multi-valued mapping of inverse hysteresis into a one-to-one mapping. Based on the constructed expanded input space, a neural network is employed to approximate the inverse hysteresis. Both experiment and simulation are implemented to validate the effectiveness of the proposed approach. These results indicate that the proposed approach has derived satisfactory modeling performance.     

利用光杠杆法测量金属丝的弹性滞后环

利用大学物理实验中的光杠杆法测定金属丝弹性模量的原理和设备,对具有超弹性的NiTi丝的弹性滞后环进行了测定结果表明,此种方法可以很好地测定NiTi丝的弹性滞后环,而且操作简单使用方便,是一种非常有效的测定金属细丝弹性滞后环的方法.     

Automatic Alignment of Optical System Using Shape Memory Alloy

Properties of the shape memory alloy of 29 μm thick Ni-Ti foil are investigated as an actuator to align optical elements. Since the intrinsic properties of the Ni-Ti foil are not satisfactory in reproducibility and hysteresis, a simple feedback control is used. A pinhole integrated with a surrounding position sensor is proposed to realize a confocal optical system having an automatic alignment function. Large displacement (mm) and precision at the level of the optical wavelength are found to be possible.Present at 1996 International Workshop on Interferometry (IWI ‘96), August 27-29, Saitama, Japan.     

Ultrafast All-Optical Serial-to-Parallel Conversion and Its Application to Optical Label Processing

A novel scheme for all-optical serial-to-parallel conversion (SPC) is proposed for label recognition of ultrafast asynchronous burst optical packets. Compact SP converter modules were developed using a fiber array or a surfaceemitting planar lightwave circuit, and 1-Tbit/s and 40-Gbit/s SPC for 16-bit optical packets is demonstrated using the modules. The key device in the converter is a spin-polarized surface-reflection all-optical switch (LOTOS) with an ultrafast switching time (250 fs) and an extremely high on/off ratio (>30 dB). Label recognition of 40-Gbit/s 16-bit burst-mode optical packets is experimentally confirmed using an optical clock-pulse generator and a complementary metal-oxide-semiconductor (CMOS) electronics circuit as well as the all-optical SP converter. 1 x 4 self-routing is also demonstrated using 2-channel control signals generated from the CMOS circuit according to a routing table.     

Realizing reliable logic and memory function with noise-assisted Schmitt trigger circuits

Schmitt trigger is a comparator circuit with hysteresis, implemented by applying positive feedback to a noninverting input. Recently, it has been verified that noise under certain condition can help nonlinear circuit to realize reliable logical stochastic resonance (LSR). In this letter, we demonstrate that, without any modifications, Schmitt trigger can operate flexibly both as logic operation and latch operation in an optimal noise range. In traditional Schmitt trigger, the hysteresis is designed for resisting noise. In the new design, the hysteresis tends to enhance the LSR effect in Schmitt trigger with the help of noise and helps the system to perform better at higher noise levels. Thus, our results extend the application scope and generality of the traditional Schmitt trigger.     

Dynamical switching and memory via incoherent pump assisted optical bistability

We analyze the dynamical behavior of all-optical switching and memory based on tunable optical bistability in a three-level Λ-type atomic system driven by a probe field circulating in an optical ring cavity, a coherent coupling field and an incoherent pump field outside cavity. Owing to the incoherent pump process, the absorption and Kerr nonlinearity near the atomic resonance change dramatically as a result of varied population distribution and atomic coherence, and then the switch-up and switch-down thresholds, as well as the width (or area) of bistable curve, can be manipulated effectively. By tuning the intensity of either coherent coupling field or incoherent pump field, we can make the system output flip between the lower and upper branches of different bistable hysteresis loops while the cavity input keeps to a constant value. Accordingly, all-optical switching and memory can be implemented via dynamical control of the bistable behavior under the assistance of incoherent pump. The proposed scheme can find potential applications in all-optical communication and computation.