909 research outputs found
Conduction mechanism of Co-doped ZnO transparent memristive devices
No full textThe Co dopant substitutes the Zn atomic position in the hexagonal crystal lattice and generates acceptor defects. These defects play significant role in modulating the conduction mechanism of the memristive device. The devices without Co dopant have high concentration of donor defects so that the electron can flow easily through hopping these donor defects; henceforth, only weak filaments can be formed during the set process. Meanwhile, the increase of the acceptor defects in the films enhances the film resistivity. This acceptor defects also contribute to an increase of barrier height at the electrode/dielectric interface where the electrons require higher energy to overcome this barrier and, eventually, induce the formation of strong filaments during the set process
Annealing induced cation diffusion in TaOx-based memristor and its compatibility for back-end-of-line post-processing
No full textThe effect of annealing on the switching characteristics of memristor devices cannot be overlooked because the thermal process can exhibit both positive and negative effects on the performance of the devices. We investigated the switching behavior of TaOx-based memristors (electrochemical metallization cell type, ECM) that were Ar-ambient annealed under two conditions, with and without the active electrode. We found a high concentration of metal species in the TaOx films, even in the device where the TaOx was annealed without the active top electrode. This indicates that the properties of the annealed films encourage the diffusion of metal species in the oxide. We suggest that the increase in non-lattice oxygen (by 4.1%, indicating a higher concentration of Vo defects) after the annealing process plays a role in this phenomenon. In addition, the concentration of metal species that exist prior to the switching activation as well as the structure of the conducting bridge determines the switching stability of the devices. The device that annealed before top electrode deposition shows the worst stability; conversely, the device that annealed after top electrode deposition has the best coefficient of variation of the LRS and HRS which is 4.69% and 78.8%, respectively. Electrical and materials analyses were conducted to understand this phenomenon. This study provides insight into the compatibility of ECM in CMOS post-processing
Development of collagen scaffold with internal channels via indirect rapid prototyping
No full text202 p.The author would like to take this opportunity to acknowledge the contribution of anumber of people for this project. The realization of the project would not have beenpossible without the advice and assistance from them.The author wishes to express her sincere gratitude and appreciation to A/P Chua CheeKai, A/P Leong Kah Fai and Dr. Margam Chandrasekaran, for their invaluable adviceand motivation throughout the project. Appreciation is also extended to As/P AlastairCampbell Ritchie from the School of Mechanical and Aerospace Engineering, NTU,and Mr Timothy Tan and Dr Peter Lee from DNA Center, NIE, for their guidance inthe project. Heartfelt thanks to Ms Hu Quijun, from SIMTech for her guidance andsupport.DOCTOR OF PHILOSOPHY (MAE
Performance of a self-correlating synchronization and detection scheme for IR-UWB in multi-user multipath environments
No full textOwing to the very low duty cycle of impulse like ultra wideband signals, timing acquisition with acceptable accuracy and complexity has been a constant topic of research. Most acquisition techniques can be broadly classified under two categories: Training based algorithms, which require a specific training sequence at the start of communication and - Blind Acquisition, which relies on the correlation between successive data symbols transmitted and cyclostationarity of the transmitted signal. Amidst algorithms which use a clean template or a noiseless reference, a recent class of techniques named 'Timing based on Dirty Templates' (TDT) has been proposed.
These algorithms rely on the correlation of two adjacent portions of the noisy received signal. One portion of the noisy received signal acts as a template for the other, thus improving the synchronization speeds and accuracy by making the acquisition independent of training sequences. A novel blind TDT algorithm, which we refer to as Agrawal Blind Synchronization scheme (ABS), was proposed for IR-UWB signals. Based on the design of the time hopping code, significant improvements in acquisition speeds have been demonstrated using the ABS scheme, compared to existing blind acquisition schemes.
The objective of this thesis is to analyze the performance capabilities of the selfcorrelating ABS scheme in multi-user multipath environments. Adopting the best performing time hopping pattern, we investigate the effect of multiple interferers on absolute timing error, under various SNR scenarios as well as multiple symbols used for timing acquisition. Link performance is evaluated through bit-error-rate (BER) analysis under various system conditions. Since we use differential methods for timing acquisition as well as symbol detection, significant energy capture can be achieved in a dense multipath scenario due to self-Raking. We also propose modifications to conventional differential detectors to avoid self-Raking of interfering pulses. As a comparison to differential detectors, the detection performance of an ideal Rake receiver was tested with the ABS scheme. Our results indicate that the timing error performance the ABS scheme and thus the BER performance of the detection phase deteriorate notably with increase in the number of users in the system. The effective number of interferers is the limiting factor in both absolute timing error and BER performance. In differential detection, the effect of interference is so large it dominates over the effect of timing errors. The use of the ABS scheme is advantageous when Rake receivers are used, since timing error has a drastic effect of degrading the BER performance. The improvements of using ABS scheme in multi-user multi-path environments become more prominent in the case of ideal Rake reception, as compared to differential detection.M.S.Includes bibliographical references (p. 63-66)
Concept Based Author Recommender System for CiteSeer
No full textThe information explosion in today's electronic world has created the need for information filtering techniques that help users filter out extraneous content to identify the right information they need to make important decisions. Recommender systems are one approach to this problem, based on presenting potential items of interest to a user rather than requiring the user to go looking for them. In this paper we propose a recommender system that recommends research papers of potential interest to the author from the CiteSeer database. For each author participating in the study, we create a user profile based on their previously published papers. Based on similarities between the user profile and profiles for documents in the collection, additional papers are recommended to the author. We introduce a novel way of representing the user profiles as tree of concepts and an algorithm for computing the similarity between the user profiles and document profiles using a tree-edit distance measure. Experiments with a group of volunteers show that our tree based algorithm provides better recommendations than a traditional vector-space model based technique
How do practitioners, PhD students and postdocs in the social sciences assess topic-specific recommendations?
No full text"In this paper we describe a case study where researchers in the social sciences (n=19) assess topical relevance for controlled search terms, journal names and author names which have been compiled by recommender services. We call these services Search Term Recommender (STR), Journal Name Recommender (JNR) and Author Name Recommender
(ANR) in this paper. The researchers in our study (practitioners, PhD students and postdocs) were asked to assess the top n preprocessed
recommendations from each recommender for specific research topics which have been named by them in an interview before the experiment. Our results show clearly that the presented search term, journal name and author name recommendations are highly relevant to the researchers topic and can easily be integrated for search in Digital Libraries. The average precision for top ranked recommendations is 0.749 for author names, 0.743 for search terms and 0.728 for journal names.
The relevance distribution differs largely across topics and researcher types. Practitioners seem to favor author name recommendations while postdocs have rated author name recommendations the lowest. In the experiment the small postdoc group favors journal name recommendations." (author's abstract
Antibacterial activity of neem nanoemulsion and its toxicity assessment on human lymphocytes in vitro
No full textJayakumar Jerobin, Pooja Makwana, RS Suresh Kumar, Rajiv Sundaramoorthy, Amitava Mukherjee, Natarajan Chandrasekaran Centre for Nanobiotechnology, VIT University, Vellore, Tamil Nadu, India Abstract: Neem (Azadirachta indica) is recognized as a medicinal plant well known for its antibacterial, antimalarial, antiviral, and antifungal properties. Neem nanoemulsion (NE) (O/W) is formulated using neem oil, Tween 20, and water by high-energy ultrasonication. The formulated neem NE showed antibacterial activity against the bacterial pathogen Vibrio vulnificus by disrupting the integrity of the bacterial cell membrane. Despite the use of neem NE in various biomedical applications, the toxicity studies on human cells are still lacking. The neem NE showed a decrease in cellular viability in human lymphocytes after 24 hours of exposure. The neem NE at lower concentration (0.7–1 mg/mL) is found to be nontoxic while it is toxic at higher concentrations (1.2–2 mg/mL). The oxidative stress induced by the neem NE is evidenced by the depletion of catalase, SOD, and GSH levels in human lymphocytes. Neem NE showed a significant increase in DNA damage when compared to control in human lymphocytes (P<0.05). The NE is an effective antibacterial agent against the bacterial pathogen V. vulnificus, and it was found to be nontoxic at lower concentrations to human lymphocytes. Keywords: neem, nanoemulsion, antibacterial, lymphocytes, cytotoxicity, genotoxicit
SChuBERT:Scholarly Document Chunks with BERT-encoding boost Citation Count Prediction
No full textPredicting the number of citations of scholarly documents is an upcoming task in scholarly document processing. Besides the intrinsic merit of this information, it also has a wider use as an imperfect proxy for quality which has the advantage of being cheaply available for large volumes of scholarly documents. Previous work has dealt with number of citations prediction with relatively small training data sets, or larger datasets but with short, incomplete input text. In this work we leverage the open access ACL Anthology collection in combination with the Semantic Scholar bibliometric database to create a large corpus of scholarly documents with associated citation information and we propose a new citation prediction model called SChuBERT. In our experiments we compare SChuBERT with several state-of-the-art citation prediction models and show that it outperforms previous methods by a large margin. We also show the merit of using more training data and longer input for number of citations prediction
CiteTracked:A Longitudinal Dataset of Peer Reviews and Citations
No full textScientific dissemination is of central importance for the scientific process. This paper presents CiteTracked, a dataset of peer reviews and citation statistics covering scientific papers from the machine learning community and spanning six years. We describe and analyze the data collection of over 3,000 published papers, their peer review texts and citation counts, and depict possible usage directions. The dataset aims at fertilizing novel interdisciplinary work between fields such as scientometrics, information retrieval, computational linguistics and natural language processing to study the scientific publishing process
CiteTracked:A Longitudinal Dataset of Peer Reviews and Citations
No full textScientific dissemination is of central importance for the scientific process. This paper presents CiteTracked, a dataset of peer reviews and citation statistics covering scientific papers from the machine learning community and spanning six years. We describe and analyze the data collection of over 3,000 published papers, their peer review texts and citation counts, and depict possible usage directions. The dataset aims at fertilizing novel interdisciplinary work between fields such as scientometrics, information retrieval, computational linguistics and natural language processing to study the scientific publishing process
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