忆阻逾渗导电模型中的初态影响

逾渗网格模型是当前忆阻器件机理分析研究领域的热点之一, 但现有模型缺乏对初态设定的讨论. 本文对逾渗网格模型进行了简化, 并基于此, 通过电压激励步进的方式, 研究了不同初态对单极性忆阻开关元件中逾渗导电通道形成的影响, 分析了形成通道的动态过程以及相应的物理意义, 验证了忆阻开关元件高低阻态的阻值实际表现为高斯分布而非理想双值稳态; 而不同初态条件下, 忆阻开关元件导电通道的形状存在着不同的"树形"结构, 进而影响着其阻值的分布. 研究成果有助于进一步揭示忆阻器尚未明确的导电机理, 为今后对具体不同类型的忆阻元件的初态分析提供指导性作用. 关键词： 忆阻器 开关元件 逾渗模型 初态分析     

有限时区非线性系统的最优切换控制

This paper proposes a optimal control problem for a general nonlinear systems with finitely many admissible control settings and with costs assigned to switching of controls. With dynamic programming and viscosity solution theory we show that the switching lower-value function is a viscosity solution of the appropriate systems of quasi-variational inequalities(the appropriate generalization of the Hamilton-Jacobi equation in this context) and that the minimal such switching-storage function is equal to the continuous switching lower-value for the game. With the lower value function a optimal switching control is designed for minimizing the cost of running the systems.     

随机系统的Peuteman-Aeyels指数稳定性定理

把Peuteman-Aeyels指数稳定性定理从确定性系统推广到随机系统.并借此讨论了随机混杂系统的均方指数镇定问题,得出了系统在同步切换下可镇定的充分必要条件.     

High throughput N-modular redundancy for error correction design of memristive stateful logic

Memristive stateful logic is one of the most promising candidates to implement an in-memory computing system that computes within the storage unit. It can eliminate the costs for the data movement in the traditional von Neumann system. However, the instability in the memristors is inevitable due to the limitation of the current fabrication technology, which incurs a great challenge for the reliability of the memristive stateful logic. In this paper, the implication of device instability on the reliability of the logic event is simulated. The mathematical relationship between logic reliability and redundancy has been deduced. By combining the mathematical relationship with the vector-matrix multiplication in a memristive crossbar array, the logic error correction scheme with high throughput has been proposed. Moreover, a universal design paradigm has been put forward for complex logic. And the circuit schematic and the flow of the scheme have been raised. Finally, a 1-bit full adder (FA) based on the NOR logic and NOT logic is simulated and the mathematical evaluation is performed. It demonstrates the scheme can improve the reliability of the logic significantly. And compared with other four error corrections, the scheme which can be suitable for all kinds of R-R logics and V-R logics has the best universality and throughput. Compared with the other two approaches which also need additional complementary metal-oxide semiconductor (CMOS) circuits, it needs fewer transistors and cycles for the error correction.     

Memristance controlling approach based on modification of linear M–q curve

The memristor has broad application prospects in many fields, while in many cases, those fields require accurate impedance control. The nonlinear model is of great importance for realizing memristance control accurately, but the im- plementing complexity caused by iteration has limited the actual application of this model. Considering the approximate linear characteristics at the middle region of the memristance-charge （M-q） curve of the nonlinear model, this paper pro- poses a memristance controlling approach, which is achieved by linearizing the middle region of the M-q curve of the nonlinear memristor, and establishes the linear relationship between memristances M and input excitations so that it can realize impedance control precisely by only adjusting input signals briefly. First, it analyzes the feasibility for linearizing the middle part of the M-q curve of the memristor with a nonlinear model from the qualitative perspective. Then, the lin- earization equations of the middle region of the M-q curve is constructed by using the shift method, and under a sinusoidal excitation case, the analytical relation between the memristance M and the charge time t is derived through the Taylor series expansions. At last, the performance of the proposed approach is demonstrated, including the linearizing capability for the middle part of the M-q curve of the nonlinear model memristor, the controlling ability for memristance M, and the influence of input excitation on linearization errors.     

Computation of the locus crossing point location of MC circuit

In this paper, the crossing point property of the i-v hysteresis curve in a memristor-capacitor （MC） circuit is analyzed. First, the ideal passive memristor on the crossing point property of i-v hysteresis curve is studied. Based on the analysis, the analytical derivation with respect to the crossing point location of MC circuit is given. Then the example of MC with linear memristance-versus-charge state map is demonstrated to discuss the drift property of cross-point location, caused by the frequency and capacitance value.     

脑血栓形成病人用精制蝮蛇抗栓酶治疗前后微量元素和体液免疫的变化及临床疗效的观察

用精制蝮蛇抗栓酶(Svate-3)治疗了108例急性期脑血栓形成病人,治疗前后分别测定病人血清微量元素锌、铜、铬、锰、硒及体液免疫指标 IgG, IgA, IgM及循环免疫复合物(CIC), 同时设定对照组观察 Svate-3的临床疗效.观察结果表明,治疗组疗效优于对照组.测定结果表明,Svate-3能使脑血栓病人血清 Zn增加(P＜0.05),血清 Cu减少(P＜0.05 ), Zn/Cu比值增加(P＜0.05),Svate-3可使体液免疫 IgA增加(P＜0.01) .     

生物转化生产1,3-丙二醇的研究进展

综述了近几年生物转化生产1,3－丙二醇的研究进展,介绍了1,3－丙二醇工业生产的现状、生物转化的菌种及其生产能力、生物转化1,3－丙二醇的代谢途径、甘油的同底物发酵及基因工程对菌种的改造,展望了今后研究的发展方向。     

基于吹气分离富集的异烟酸-巴比妥酸分光光度法测定水中痕量氰化物

鉴于氰化物转化成氯化氰是HJ 484-2009中异烟酸-巴比妥酸分光光度法测定氰化物的独立中间环节,利用氯化氰沸点低(14℃)、稳定性好的特性,提出了基于吹气分离富集的异烟酸-巴比妥酸分光光度法测定水中痕量氰化物含量的方法。以空气为载气,以异烟酸质量浓度为17.20 g·L^-1、巴比妥酸质量浓度为8.40 g·L^-1的溶液为吸收液(pH 5.85),利用特定的分离富集装置,完成空气净化、氰化物转化成氯化氰、氯化氰分离、氯化氰吸收及转化成聚甲炔染料等一系列过程,采用分光光度计测定吸收液在600 nm处的吸光度。结果表明：当样品、吸收液的体积分别为60.0,5.00 mL,空气流量为0.10 L·min^-1,采用3级吸收,以总吸光度作为响应值时,氰化物转化系数为94.2%,富集倍数为11.3倍,检出限(3s/k)为0.1μg·L^-1,测定线性范围为0.4～28.3μg·L^-1;方法用于井水及河水中痕量氰化物的测定,氰化物质量浓度为1.2～8.9μg·L^-1,回...     

基于蒙特卡洛方法的钛氧化物忆阻器辐射损伤研究

纳米钛氧化物忆阻器有望成为新一代阻性存储器基本单元并应用于辐射环境中的航天器控制及数据存储系统. 辐射能量, 强度, 方向, 持续时间等要素发生改变均可能对钛氧化物忆阻器受到的辐射损伤构成影响, 然而, 目前尚无相关具体研究. 基于以蒙特卡洛方法为核心的SRIM仿真, 本文针对宇宙射线主体组成部分——质子及 α射线定量研究了各个辐射要素与钛氧化物忆阻器辐射损伤的关联, 依据器件实测数据研究了辐射要素与导通阻抗, 截止阻抗及氧空缺迁移率等忆阻器主要参数的关系, 进一步利用SPICE仿真讨论了辐射对杂质漂移与隧道势垒共存特性的影响, 从而为评估及降低钛氧化物忆阻器辐射损伤, 提高器件应用于辐射环境的可靠性提供依据.