Enhanced resistive switching properties of HfAlOx/ZrO2- based RRAM devices

Resistive Random-Access Memory (RRAM) devices are recognized as potential candidates for next-generation memory devices, due to their smallest cell size, high write/erase speed, and endurance. Particularly, the resistive switching (RS) characteristics in oxide materials have offered new opportunities for developing CMOS-compatible high-density RRAM devices. In this study, the RS behavior of HfAlO_x/ZrO₂ thin films sandwiched structure between TiN bottom electrode and Au top electrodes were investigated. It was found that Au/HfAlO_x/ZrO₂/TiN stacks were superior in terms of RS performance when compare to Au/HfAlO_x/TiN memory stacks. The devices demonstrated a good resistance ratio of high resistance state and low resistance state ～10³ for Au/HfAlO_x/TiN and ～10⁵ for Au/HfAlO_x/ZrO₂/TiN stacks, respectively. Both stacks showed good retention characteristics (>10⁴ ?s) and endurance (>10³ cycles). The experimental current-voltage characteristics fitted with different conducting mechanisms, the linear lower bias region is dominated by ohmic conductivity, whereas the non-linear higher bias region was dominated by space-charge limited current conduction mechanism.     

一维稳态导热过程中的传递

依据热力学第二定律和傅里叶导热定律，建立了一维稳态导热过程中的传递方程及损方程，并分析了传递与热传递的本质区别。     

裂隙连通性研究的重正化群方法——以一个二维裂隙模式为例

文章提出一种二维裂隙网络模式，依据标度不变性原理，运用重正化群技术求取了裂隙网络模型连通概率的临界值为０．２９２８９３３，对应的单条裂隙导通的临界概率Ｐ０ｃ为０．３５８１２０９。当单条裂隙的导通概率Ｐｂ小于Ｐ０ｃ时，网络连通仅是局部的；而当单条裂隙的连通概率Ｐｂ大于Ｐ０ｃ时，则整个裂隙网络是连通的。同时求取了关联长度指数值和分维。     

Windows95与DOS、Windows3.x双重引导的实现方法

利用OS／2操作系统硬盘分区功能，在同一硬盘上建立两个主分区，再在两个主分区上安装两个操作系统称为双重引导。本文详细介绍了这一方法，为解决现有某些软件和硬件与Windows95不兼容问题，找到了较好的途径。     

粘土空心砖的热物理性能分析

本文提出热物理性能应作为粘土空心砖的主要性能指标，并对粘土空心砖的传热过程和热导率进行了分析。     

Conduction of the impulse in the ischemic myocardium — implications for malignant ventricular arrhythmias

Summary Ventricular arrhythmias occurring consequent to regional disturbances of myocardial perfusion are the most frequent cause of sudden cardiac death. They are related to marked changes of impulse propagation in the ischemic region, which consist of circulating excitation with re-entry. Mapping of the impulse during ventricular tachycardias and ventricular fibrillation shows that the circus movements change their shape and localization from beat to beat. Zones of tissue which block the impulse during one beat may conduct the impulse at a fast rate during the next beat. The main cause underlying this behavior is the depression of the ischemic action potential. This depression is caused by the partial inactivation and the prolonged recovery of the rapid sodium inward current. In addition to the decrease in resting potential, other factors, such as acidosis, contribute to the inactivation of the inward currents generating the upstroke of the action potential. An increase of coupling resistance between myocardial cells and/or an increase of extracellular resistance appear to be less important for explaining conduction disturbances in acute ischemia.     

Cu_xS法导电PAN纤维的导电耐久性研究

本文对CU_xS法导电PAN纤维的导电耐久性不理想的表现和原因进行了分析。提出一系列提高导电耐久性的措施,指出活化预处理和多硫化物后处理对提高导电耐久性具有明显的效果,并对其作用机理进行了探讨。在此基础上制得了导电耐久性优良的导电PAN纤维。     

有相变及无相变情况下导热相似分析的进一步发展

相变导热和很多实际工程问题有关.例如铸件的凝固,宇宙飞船回收地面时的相变冷却,以及相变储能等.到目前为止只有一维的相变导热才有精确的解析解.即stefan问题.本文通过相似分析对更接近实际的二维相变导热进行了研究。本文首次把导热问题中温度场的相似分析推论到积分热流量,从而简化了热流量的计算.其次文章对有相变及无相变情况下楔形物体导热的相似性作了研究,获得下述规律;对边界恒温的楔形物体在时间t_1时通过任意楔形边界面r_1的积分热流量等于在时间t_2时通过扩大了的边界面r_2的积分热流量.其中r和t构成一个无因次相似变量。这一相似性进一步引伸出相变导热中有“楔形不变量”的的存在. 运用积分热流量的相似概念本文提出了热流量计算的简化公式.     

Impulse propagation from the SA-node to the ventricles

Summary Normally the pacemaker of the mammalian heart is located in the sinus node. In the rabbit the sinus node can be subdivided into two regions, the center of the node where the impulse originates and the border zone through which the impulse is conducted towards the atrium. Conduction properties of both regions were investigated. It appeared that conduction velocity increases and refractoriness decreases when one goes from the nodal center towards the atrium. The tissue mass of the atrium is large in comparison to the sinus node and normally the resting membrane potential of atrial fibers is more negative than that of nodal fibers; consequently, a potential difference exists causing a current flow between both areas. Evidently this hyperpolarizing current flow depresses impulse formation in the border zone fibers which have better intrinsic pacemaker properties than fibers in the nodal center. If the impulse has reached the atrium it is conducted with a relatively high safety factor and will reach the AV node in principle without difficulty. The AV node, if deprived of sinus nodal dominance, develops spontaneous activity originating from the lower nodal fibers. Also in this structure, electrotonic depression by surrounding tissue causes deceleration of the pacemaker.