Ni2V2O7 dandelion microsphere for a high-performance electrocatalyst in water splitting

Water splitting is an effective way to produce hydrogen to solve the energy crisis problem, and inorganic metal compounds are widely used in electrocatalysis field due to efficient hydrogen evolution reaction (HER). Herein, we synthesize Ni₂V₂O₇ dandelion microsphere from nickel nitrate and vanadium pentoxide by “one-step hydrothermal” way, which exhibits large specific surface area of 102.74 m² g⁻¹. The as-prepared Ni₂V₂O₇ microsphere shows good electrocatalysis performances including OER overpotential of 358 mV and good stability, as well as HER overpotential of 195 mV. Furthermore, the Ni₂V₂O₇ microsphere electrode is assembled to Ni₂V₂O₇ microsphere//Ni₂V₂O₇ microsphere system, showing the water splitting voltage of 1.50 V at 10 mA cm⁻² by two-electrode method, which is much lower than those of commercial RuO₂//Pt/C system and most of spinel oxides electrocatalysts. Our work opens up a new and facile avenue for fabricating inorganic microsphere electrocatalyst in hydrogen production field.     

新三维分段线性混沌系统

提出了一个新三维分段线性混沌系统,研究了新系统的对称性和不变性、耗散性和吸引子的存在性、平衡点及稳定性等基本动力学特性。利用相轨图、庞加莱映射、李雅普诺夫指数谱和分岔图等数值仿真手段,验证了该系统能运行在混沌和周期轨道,具有丰富的动力学行为,并能通过一个常数控制器控制到不同形状混沌吸引子的混沌轨道或周期轨道或一个有界点。     

基于朴素基因表达式编程挖掘紧致函数

基因表达式编程(GEP)是一种基因型和表现型相分离的进化新模型,为了挖掘紧致的函数关系,分析了进化系统各因素对挖掘紧致函数的影响,提出了带紧致压力的适应度函数来进化函数紧致解。实验表明,带有紧致压力的适应度函数能自动进化计算机程序,适合挖掘的紧致关系,在挖掘紧致函数中,朴素基因表达式编程(NGEP)比GEP提高效率21.7%,与不带压力的系统相比,GEP的平均压缩了31.2%,NGEP系统平均压缩了42.5%;NGEP较GEP更容易发现紧致解,且函数表达形式更容易理解,丰富了NGEP理论.     

决策粗糙集属性约简算法与属性核研究

属性约简是粗糙集理论的重要研究内容之一。在Pawlak粗糙集模型中,正区域大小随着属性增多而变大,呈现单调性。然而,在决策粗糙集模型中,概率正区域与属性集之间不具有单调性,从而产生各种属性约简定义。为此,深入研究了决策粗糙集属性约简问题,阐述了几种约简定义之间的关系,证明了保持局部最大概率正区域的约简具有较大的代价,指出了保持所有对象的正决策不变的约简呈现稳定性和存在属性核。     

DynamicCloudSim: Simulating heterogeneity in computational clouds

Simulation has become a commonly employed first step in evaluating novel approaches towards resource allocation and task scheduling on distributed architectures. However, existing simulators fall short in their modeling of the instability common to shared computational infrastructure, such as public clouds. In this work, we present DynamicCloudSim which extends the popular simulation toolkit CloudSim with several factors of instability, including inhomogeneity and dynamic changes of performance at runtime as well as failures during task execution. As a validation of the introduced functionality, we simulate the impact of instability on scientific workflow scheduling by assessing and comparing the performance of four schedulers in the course of several experiments both in simulation and on real cloud infrastructure. Results indicate that our model seems to adequately capture the most important aspects of cloud performance instability. The source code of DynamicCloudSim and the examined schedulers is available at https://code.google.com/p/dynamiccloudsim/.     

几种开发通用题库管理系统方法的比较

研究了几种通用题库管理系统开发中的试题输入与输出方法,对这几种方法的优缺点进行比较,并给出了对应的程序代码。同时提出了自己开发通用题库管理系统中的试题的输入与输出方法,实验结果表明此方法比其它方法稳定性要好、处理效率要高。     

Bifunctional Edge-Rich Nitrogen Doped Porous Carbon for Activating Oxygen and Sulfur

Oxygen reduction reaction (ORR) and sulfur reduction reaction (SRR) play key roles in advanced batteries. However, they both suffer from sluggish reaction kinetics. Here, an interesting nitrogen doped porous carbon material that can simultaneously activate oxygen and sulfur is reported. The carbon precursor is a nitrogen containing covalent organic framework (COF), constituting periodically stacked 2D sheets. The COF structure is well preserved upon pyrolysis, resulting in the formation of edge-rich porous carbon with structure resembling stacked holey graphene. The nitrogen containing groups in the COF are decomposed into graphitic and pyridinic nitrogen during pyrolysis. These edge sites and uniform nitrogen doping endow the carbon product with high intrinsic catalytic activities toward ORR and SRR. The COF derived carbon delivers outstanding performances when assembling as cathodes in the Li-S and Li-O₂ batteries. Simultaneous activation of oxygen and sulfur also enables a new battery chemistry. A proof-of-concept Li-S/O₂ hybrid battery is assembled, delivering a large specific capacity of 2,013 mAh g⁻¹. This study may inspire novel battery designs based on oxygen and sulfur chemistry.     

一种基于行为的移动机器人目标人跟踪控制方法

针对室内复杂环境,对于智能服务移动机器人,设计一个连续稳定的目标人跟踪算法是必要的.为此提出一种室内环境下基于行为的移动机器人对运动目标人进行跟踪的控制方法,该方法综合优先级裁决方法与模糊行为融合法选取移动机器人的控制行为,较好地解决跟踪过程中存在多种行为以及行为冲突问题,在完成运动避障的同时保持对运动目标的跟踪.对避...     

蔡氏电路方程的离散化与数字电路实现*

本文提出了一种蔡氏电路方程的数字电路实现方法。利用欧拉算法、改进型欧拉算法和四阶龙格-库塔算法进行离散化近似处理,分别得到了一般混沌系统的离散迭代模型,由此导出了蔡氏电路方程在不同近似精度下的离散迭代模型。基于微控制器实现的混沌系统嵌入式数字集成平台,生成了所期望的蔡氏混沌信号,并比较了基于不同算法的蔡氏电路方程的数字电路实现的性能。数值仿真和数字电路实验结果与蔡氏混沌电路结果一致,验证了本文数字电路实现方法的可行性。     

一种由代谢方程构建网络的方法及其实现

代谢网络的拓扑结构分析和可视化是系统生物学研究的热点。如何自动合理地由数量众多的代谢方程构建代谢网络是研究者首先面临的问题。基于二部图模型,采用节点唯一化和忽略高度节点策略,提出一种由代谢方程直接构建代谢网络的方法,并给出MATLAB实现步骤,最后使用生物网络模拟软件可视化生成的代谢网络,结果表明这种方法能用来构建复杂代谢网络,并具有较好展现网络模块和拓扑结构的特点,适用于由大量代谢反应方程自动构建复杂代谢网络的一般应用需求。该方法的MATLAB源码和说明文档可以通过http://bioinf.jiangnan.edu.cn/在线获得。