42,450 research outputs found
A memristor SPICE model accounting for synaptic activity dependence
No full textIn this work, we propose a new memristor SPICE model that accounts for the typical synaptic characteristics that have been previously demonstrated with practical memristive devices. We show that this model could account for both volatile and non-volatile memristance changes under distinct stimuli. We then demonstrate that our model is capable of supporting typical STDP with simple non-overlapping digital pulse pairs. Finally, we investigate the capability of our model to simulate the activity dependence dynamics of synaptic modificationand present simulated results that are in excellent agreement with biological results
Correlated resistive/capacitive state variability in solid TiO<sub>2</sub> based memory devices
No full textIn this work, we experimentally demonstrated the correlated resistive/capacitive switching and state variability in practical TiO2 based memory devices. Based on filamentary functional mechanism, we argue that the impedance state variability stems from the randomly distributed defects inside the oxide bulk. Finally, our assumption was verified via a current percolation circuit model, by taking into account of random defects distribution and coexistence of memristor and memcapacitor
Origin of stochastic resistive switching in devices with phenomenologically identical initial states
No full textNanoscale resistive switching devices are nowadays widely employed in applications of storage, logic and computing. The switching mechanism of metal oxide based devices is normally assumed to be the filamentary formation and rupture within the devices’ active cores but the origin of filaments growth is still controversial. Previous research has already demonstrated that initial filamentary states could significantly affect the devices’ switching dynamics and final resistance distributions. Here we demonstrate the relation between pristine resistive states and distribution of filaments via modeling the switching dynamics by utilizing a current percolation circuit. We show that devices with identical initial resistive states could attain distinct plausible filamentary distributions and correspondingly manifest very dissimilar switching dynamics even when biased with similar stimuli
Assessment of Self-Archiving in Institutional Repositories: Depositorship and Full-Text Availability
No full textThis research evaluates the success of open access self-archiving in several well-known institutional repositories. Two assessment factors have been applied to examine the current practice of self-archiving: depositorship and the availability of full text. This research discovers that the rate of author self-archiving is low and that the majority of documents have been deposited by a librarian or administrative staff. Similarly, the rate of full-text availability is relatively low, except for Australian repositories. By identifying different practices of self-archiving, repository managers can create new strategies for the operation of their repositories and the development of archiving policies
Stochastic switching of TiO<sub>2</sub>-based memristive devices with identical initial memory states
No full textIn this work, we show that identical TiO2-based memristive devices that possess the same initial resistive states are only phenomenologically similar as their internal structures may vary significantly, which could render quite dissimilar switching dynamics. We experimentally demonstrated that the resistive switching of practical devices with similar initial states could occur at different programming stimuli cycles. We argue that similar memory states can be transcribed via numerous distinct active core states through the dissimilar reduced TiO2-x filamentary distributions. Our hypothesis was finally verified via simulated results of the memory state evolution, by taking into account dissimilar initial filamentary distribution
Coexistence of memory-resistance and memory-capacitance in TiO2 solid state devices
No full textThis work exploits the coexistence of both resistance and capacitance memory effects in TiO2 based two terminal cells. Our Pt/TiO2/TiOx/Pt devices exhibit an interesting combination of hysteresis and non-zero crossing in their current-voltage (I-V) characteristic that indicate the presence of capacitive states. Our experimental results demonstrate that both resistance and capacitance states can be simultaneously set via either voltage cycling and/or voltage pulses. We argue that these states modulations occur due to bias induced reduction of the TiOx active layer via the displacement of ionic species
The optimal equilibrium operation between power generation and ecology of Qingjiang cascade hydropower stations
No full textEcological operation of cascade hydropower stations is one of the most important methods for the ecological restoration of a river system. In order to balance the benefits between power generation and ecology of Qingjiang cascade hydropower station, an optimal equilibrium operation method is proposed in this paper. Firstly, the range of ecological flow of the Qingjiang cascade is calculated by using ten-day frequency calculation method. Secondly, an optimal equilibrium operation model by considering the balance between power generation and ecology is established. And then, in order to solve this complex model, a particle swarm optimization based model solution method is proposed, and the evaluation index system of operation schemes is established. Finally, through operation calculation in 2008-2010 years, the results show that compared with the operation scheme considering only power generation benefit, the optimal equilibrium operation scheme increases the runoff ecological dispersion coefficient by 6.90%，reduces the cascade ecological overflow by 7.739 billion m3 and the cascade ecological water shortage by 130 million m3, while the cascade power generation decreases slightly by 1.83%. This study provides an effective scientific method for the optimal operation of Qingjiang cascade under the background of Yangtze River protection
Joint Operation of the Multi-Reservoir System of the Three Gorges and the Qingjiang Cascade Reservoirs
No full textOptimal utilization of available water resources has become more urgent due to the rapid growth of the economy and population. The joint operation of the Three Gorges cascade and Qingjiang cascade reservoirs in China was studied in this paper. Choosing maximization of hydropower generation and hydropower revenue as objective functions respectively, optimal models were established for individual and joint operation of the cascade reservoirs. The models were solved by the progressive optimality algorithm. The storage and electric compensation benefits among cascade reservoirs were analyzed. The daily inflow data of consecutive hydrological years of 1982–1987 were selected for a case study. Compared with the design operation rule, the joint operation of the multi-reservoir system can generate 5.992 billion kWh of extra power or an increase of 5.70% by the objective function of maximum hydropower generation. Through reservoir storage compensation, the spilled water of the Three Gorges and Qingjiang cascade reservoirs was decreased by 78.741 and 5.384 billion m3, respectively
Length-weight relationships of nine fish species from the Qingjiang River, Yangtze River basin, China
No full textThis study presents the first report of length-weight relationships (LWRs) for five fish species (Parabotia fasciata, Megalobrama mantschuricus, Plagiognathops microlepis, Rhodeus sinensis, Rhodeus fangi) and maximum total lengths for four species from the Qingjiang River, Yangtze River basin, China. Specimens were sampled in six sections along the Qingjiang River over a period of 1 year between April 2016 and March 2017 with gill nets (150 x 10 m; mesh size: 1-14 cm), benthic fyke nets (mouth opening: 12 x 12 cm; 10 m; mesh size: 1 cm) and stationary lift nets (10 x 10 m; mesh size: 0.8cm)
Information Literacy and Librarian-Faculty Collaboration: A Model for Success:
No full textIn the age of information explosion and technological advancement, issues of information storage, organization, access, and evaluation have become necessarily important in our societies. Addressing issues of information literacy and designing how they can be best integrated in students' learning process are of critical importance. Library professionals in the United States, particularly in the academia, have realized the importance of information literacy and have attempted in various ways to address these issues. The ultimate goal is to make information literacy an integral part of the academic curriculum, thus helping students to succeed not only during their years in college but also for their lifelong career choices. This article will look at ways of how information literacy can best be incorporated into students' academic experience, and how this process can make students' learning meaningful and successful. Specifically, the author will examine the model of librarian-faculty collaboration in integrating information literacy into the curriculum, as demonstrated in the Ohio Five Colleges' Information Literacy Program.Publisher version of this article is available at: http://www.white-clouds.com/iclc/cliej/cl24.ht
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