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排序方式: 共有1636条查询结果,搜索用时 109 毫秒
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Biorealistic Implementation of Synaptic Functions with Oxide Memristors through Internal Ionic Dynamics 下载免费PDF全文
Chao Du Wen Ma Ting Chang Patrick Sheridan Wei D. Lu 《Advanced functional materials》2015,25(27):4290-4299
Memristors have attracted broad interest as a promising candidate for future memory and computing applications. Particularly, it is believed that memristors can effectively implement synaptic functions and enable efficient neuromorphic systems. Most previous studies, however, focus on implementing specific synaptic learning rules by carefully engineering external programming parameters instead of focusing on emulating the internal cause that leads to the apparent learning rules. Here, it is shown that by taking advantage of the different time scales of internal oxygen vacancy (VO) dynamics in an oxide‐based memristor, diverse synaptic functions at different time scales can be implemented naturally. Mathematically, the device can be effectively modeled as a second‐order memristor with a simple set of equations including multiple state variables. Not only is this approach more biorealistic and easier to implement, by focusing on the fundamental driving mechanisms it allows the development of complete theoretical and experimental frameworks for biologically inspired computing systems. 相似文献
33.
In this paper we consider the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential. By the Lp type estimates and the theory of Morrey spaces, we prove the HSlder continuity of the solutions. Then we obtain the existence of global classical solutions. The present work can be viewed as an extension to the previous work on the Cahn-Hilliard equation with concentration dependent mobility and potential. 相似文献
34.
Mechanistic insights into the structure‐dependent selectivity of catalytic furfural conversion on platinum catalysts 下载免费PDF全文
Qiu‐Xia Cai Jian‐Guo Wang Yang‐Gang Wang Donghai Mei 《American Institute of Chemical Engineers》2015,61(11):3812-3824
The effects of surface structures on the selectivity of catalytic furfural conversion over platinum (Pt) catalysts in the presence of hydrogen have been studied using first principles density functional theory (DFT) calculations and microkinetic modeling. Three Pt model surface structures, that is, flat Pt(111), stepped Pt(211), and Pt55 cluster are chosen to represent the terrace, step, and corner sites of Pt nanoparticle. DFT results show that the dominant reaction route (hydrogenation or decarbonylation) in furfural conversion depends strongly on the structures (or reactive sites). Using the size‐dependent site distribution rule, our microkinetic modeling results indicate the decarbonylation route prevails over smaller Pt particles less than 1.4 nm while the hydrogenation is the dominant reaction route over larger Pt catalyst particles at T = 473 K and = 93 kPa. This is in good agreement with the reported experimental observations. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3812–3824, 2015 相似文献
35.
filtering for switched discrete‐time systems under asynchronous switching: A dwell‐time dependent Lyapunov functional method 下载免费PDF全文
Weiming Xiang Jian Xiao Magdi S. Mahmoud 《International Journal of Adaptive Control and Signal Processing》2015,29(8):971-990
In this article, the filtering problem for switched discrete‐time linear systems under asynchronous switching is addressed in the framework of dwell time, where ‘asynchronous switching’ covers more general and practical cases, for example, the switching lags caused by mode identification process are taken into consideration. Firstly, a novel dwell‐time dependent Lyapunov function (DTDLF) is introduced to solve stability and ?2 gain analysis problems. The main advantage of DTDLF approach is that the derived conditions are all convex in system matrices, so it is convenient to be applied into filter design with performance instead of weighted performance as many other previous results. Thus, on the basis of DTLDF, a dwell‐time dependent filter with time‐varying structure is proposed to achieve the desirable non‐weighted filtering performance. It is notable that the proposed approach can also easily characterize the relationships among filtering performance, dwell time, and asynchronous time. Two examples are provided to validate the theoretical findings in this paper. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
36.
Oxidative Metabolism of Ferrocene Analogues of Tamoxifen: Characterization and Antiproliferative Activities of the Metabolites 下载免费PDF全文
Dr. Marie‐Aude Richard Dr. Didier Hamels Dr. Pascal Pigeon Dr. Siden Top Dr. Patrick M. Dansette Hui Zhi Shirley Lee Dr. Anne Vessières Dr. Daniel Mansuy Prof. Gérard Jaouen 《ChemMedChem》2015,10(6):981-990
Ferrociphenols have been found to have high antiproliferative activity against estrogen‐independent breast cancer cells. The rat and human liver microsome‐mediated metabolism of three compounds of the ferrocifen ( FC ) family, 1,1‐bis(4‐hydroxyphenyl)‐2‐ferrocenyl‐but‐1‐ene ( FC1 ), 1‐(4‐hydroxyphenyl)‐1‐(phenyl)‐2‐ferrocenyl‐but‐1‐ene ( FC2 ), and 1‐[4‐(3‐dimethylaminopropoxy)phenyl]‐1‐(4‐hydroxyphenyl)‐2‐ferrocenyl‐but‐1‐ene ( FC3 ), was studied. Three main metabolite classes were identified: quinone methides ( QM s) deriving from two‐electron oxidation of FC s, cyclic indene products ( CP s) deriving from acid‐catalyzed cyclization of QM s, and allylic alcohols ( AA s) deriving from hydroxylation of FC s. These metabolites are generated by cytochromes P450 (P450s), as shown by experiments with either N‐benzylimidazole as a P450 inhibitor or recombinant human P450s. Such P450‐dependent oxidation of the phenol function and hydroxylation of the allylic CH2 group of FC s leads to the formation of QM and AA metabolites, respectively. Some of the new ferrociphenols obtained in this study were found to exhibit remarkable antiproliferative effects toward MDA‐MB‐231 hormone‐independent breast cancer cells. 相似文献
37.
Zachary B. Walters 《Computer Physics Communications》2011,(4):935-939
This paper presents a new technique to calculate the evolution of a quantum wavefunction in a chosen spatial basis by minimizing the accumulated action. Introduction of a finite temporal basis reduces the problem to a set of linear equations, while an appropriate choice of temporal basis set offers improved convergence relative to methods based on matrix exponentiation for a class of physically relevant problems. 相似文献
38.
A fuzzy multi‐objective water resources management model is developed to determine the satisfactory water allocation plan in a coastal city of Northeast China. The imprecise predicted values of parameters are represented by fuzzy numbers, and seven fuzzy objectives of maximizing the possibilities of satisfying the water requirements for six users and total cost less than the expected value are considered. After weighted summation method (WSM) is used to transform the multi‐objective model into a single‐objective model, the satisfactory water allocation plan is efficiently derived according to decision makers' preferences by using a hybrid solution procedure of combining genetic algorithm with fuzzy simulation technique. Results of sensitivity test imply that the interval [0.2, 0.6] of cutting level, surface water and groundwater supplies have the most sensitive influence on results of the model. Moreover, results of discussion demonstrate that the assumption of linearity can be accepted, and membership function of fuzzy number has little influence on results of the model. 相似文献
39.
This paper deals with the estimation of the intensity of a planar point process on the basis of a single point pattern, observed in a rectangular window. If the model assumptions of stationarity and isotropy hold, the method of block bootstrapping can be used to estimate the intensity of the process with confidence bounds. The results of two variants of block bootstrapping are compared with a parametric approximation based on the assumption of a Gaussian distribution of the numbers of points in deterministic subwindows of the original pattern. The studies were performed on patterns obtained by simulation of well‐known point process models (Poisson process, two Matérn cluster processes, Matérn hardcore process, Strauss hardcore process). They were also performed on real histopathological data (point patterns of capillary profiles of 12 cases of prostatic cancer). The methods are presented as worked examples on two cases, where we illustrate their use as a check on stationarity (homogeneity) of a point process with respect to different fields of vision. The paper concludes with various methodological discussions and suggests possible extensions of the block bootstrap approach to other fields of spatial statistics. 相似文献
40.