Proportional integral-fractional filter controller design for first order lag plus time delay system

In this work, a design approach of proportional integral-fractional filter (PI-FF) controller for first order plus time delay (FOPTD) system is proposed in order to enhance the feedback control system performances characteristics. The controller design method is drawn up such that the transfer function of the overall closed-loop system is equivalent to the transfer function of the general fractional Bagley–Torvik reference model whose behaviour ranges from relaxation to oscillation for different values of the fractional order derivative and the damping ratio-like parameter. The tuning parameters of the PI-FF controller are derived analytically from the FOPTD process model and the general fractional Bagley–Torvik reference model parameters. Illustrative examples were presented to test the effectiveness and the usefulness of the proposed PI-FF controller on the feedback control system performance characteristics enhancement.     

贴壁细胞超声脱壁技术研究

细胞从培养皿表层脱壁是贴壁细胞传代的必须操作,目前,胰蛋白酶消化法是细胞脱壁的主要方法,但该方法操作复杂,难以实现自动化细胞培养。此外,胰蛋白酶还会对细胞蛋白造成不可逆的伤害,造成细胞产量下降及自修复时间长等问题。超声脱壁技术使用物理手段完成细胞脱壁,可以避免损伤细胞蛋白,实现脱壁过程的自动化。该文研究了一种超声脱壁技术,采用基于亮场显微镜的细胞融合度检测方法,对超声脱壁技术的脱壁效果进行评估,以人脐带间充质干细胞为目标细胞,研究了贴壁细胞超声脱壁技术的关键控制参数。实验结果显示,当超声换能器输入电压为 255 V、超声频率为 159～161 kHz 扫频、超声时间为 2 min 时,将细胞与超声换能器距离调至 3 mm,使用 12 mL 生理盐水作为震荡液体,可以使 T75 瓶中细胞脱壁面积达到 95%,细胞成活率达到 70%。     

基于HH模型的心肌细胞电模型

提出了一种心肌细胞电生理模型的建模仿真方法。通过借助Hodgkin-Huxley模型对单个心肌细胞建立细胞膜的等效电路模型,利用四阶Rouge-Kutta算法,研究并分析了心肌细胞膜内外离子电流及电位差变化。然后用C语言完成了对细胞膜等效电路模型的编程,利用Matlab软件平台进行了计算机仿真,得到了心肌细胞电生理学模型在不同刺激下的仿真实验结果。     

A family of approximate inertial manifolds for a Van der Pol/FitzHugh–Nagumo perturbation problem

We investigate the stability of a family of approximate inertial manifolds (AIMs) obtained from an ODE containing a perturbation parameter. For two choices of the parameter, the dynamics associated with the equations are already well known: in one case, we have a Van der Pol equation, while in the other setting we obtain a FitzHugh–Nagumo equation. Recently, it has been shown that (a modified version of) each equation admits a sequence of AIMs which converges to the inertial manifold. We show that our model admits a family of AIMs depending on the perturbation parameter. We then investigate the stability of the family of AIMs as the perturbation parameter approaches two different vanishing coefficient limits. These results are intended to shed insight into the continuity properties of inertial manifolds.     

Novel passivity criteria for neural networks with discrete and unbounded distributed time-varying delays

Novel passivity criteria are presented for the passivity of a class of cellular neural networks with discrete and unbounded distributed time-varying delays. Two types of uncertainty are considered: one is time-varying structured uncertainty while the other is interval uncertainty. The Gu's discretized Lyapunov–Krasovskii functional method is integrated with the technique of introducing the free-weighting matrix between the terms of the Leibniz–Newton formula. The integrated method leads to the establishment of new delay-dependent sufficient conditions in form of linear matrix inequalities for passivity of delayed neural networks. A numerical simulation study is conducted to demonstrate the obtained theoretical results, which shows their less conservatism than the existing passivity criteria.     

A linearly semi-implicit compact scheme for the Burgers–Huxley equation

In this paper, a linearly semi-implicit compact scheme is developed for the Burgers–Huxley equation. The equation is decomposed into two subproblems, i.e. a Burgers equation and a nonlinear ODE, by the operator splitting technique. The Burgers equation is solved by a linearly self-starting compact scheme which is fourth-order accurate in space and second-order accurate in time. The nonlinear ODE is discretized by a third-order semi-implicit Runge–Kutta method, which possesses good numerical stability with low computational cost. The numerical experiments show that the scheme provides the expected convergence order. Finally, several experiments are conducted to simulate the solutions of the Burgers–Huxley equation to validate our numerical method.     

Single‐cell‐gap transflective liquid‐crystal display and the use of photoalignment technology

Abstract— In this paper, transflective liquid‐crystal‐display (LCD) technology will be reviewed, and several new single‐cell‐gap transflective LCD configurations are proposed. Photoalignment technology is studied especially for transflective‐LCD applications. In order to realize the optimal performance of the display as well as a matched transmittance/reflectance voltage curve (TVC/RVC) for the transflective configurations, two different single‐cell‐gap transflective‐LCD approaches will be discussed. The first one is the dual‐mode single‐cell‐gap approach, in which different liquid‐crystal modes are applied to the transmissive and reflective subpixels of the transflective LCD. The other approach is the single‐mode s ingle‐cell‐gap approach, in which an in‐cell retardation film is applied to adjust the performance and TVC/RVC matching of a transflective LCD. Photoalignment technology is used to fabricate the dual‐mode liquid‐crystal cell in the first approach and also the in‐cell retardation film in the second approach. Prototypes of the proposed configurations have been fabricated, which show good performance and a matched TVC/RVC.     

一种水清洁阳极的基于甲醇渗透的浓度传感器

提出一种基于膜电极(MEA)结构的驱动模式甲醇浓度传感器。甲醇溶液从MEA阴极流过,通过MEA渗透到阳极,Nafion膜既是电解质膜又是甲醇渗透膜。由于引入水清洁阳极,有效避免了甲醇的累积,提高了该传感器稳定性和重现性。该传感器测量范围最大可以达到5 mol/L,适合于直接甲醇燃烧电池(DMFC)系统中甲醇的监测。