14 research outputs found
Electrochemical investigation of single-walled carbon nanotubes for hydrogen storage
No full textElectrodes made of purified and open single walled carbon nanotubes behave like metal hydride electrodes in Ni-MH batteries, showing high electrochemical reversible charging capacity up to 800 mAh g(-1) corresponding to a hydrogen storage capacity of 2.9 wt% compared to known AB(5), AB(2) metal hydride electrodes. (C) 2000 Elsevier Science Ltd. All rights reserved
Bundles of aligned carbon nanotubes obtained by the pyrolysis of ferrocene-hydrocarbon mixtures: role of the metal nanoparticles produced in situ
No full textAligned nanotube bundles have been produced by the pyrolysis of ferrocene along with methane, acetylene or butane. Ferrocene-acetylene mixtures are found to be ideal for the production of compact aligned nanotube bundles. The nanotube bundles are associated with iron nanoparticles of diameters in the range 2-13 nm. These nanoparticles are ferromagnetic, showing low saturation magnetization compared to bulk iron. The ferromagnetism of the transition metal nanoparticles is likely to be responsible for the alignment of the nanotubes
A Wavelet Multiplexing to Reduce Phase Noise Effects in OFDM based DVB-t
No full textAbstractOrthogonal Frequency Division Multiplexing (OFDM) is a highly recommended multiplexing/modulation scheme for high data rate communications due to its high spectrum efficiency and robustness against Inter Symbol Interference (ISI). The OFDM is based on dividing the available spectrum into narrow band orthogonal subcarriers and modulating data on each subcarrier. Due to long symbol period, OFDM system is more sensitive to phase noise of the oscillator compared to single carrier systems. The Phase noise of oscillators used in the transmitters & receivers results in two effects, Common Phase Error (CPE) & Inter Carrier Interference (ICI). These effects results in increasing SNR requirement at the receiver to achieve certain BER. The design & simulation of OFDM based DVB-t system with wavelet multiplexing & demultiplexing and analysis of phase noise effects on BER is presented in this paper. The performance of simulated DVB-t system is analysed by considering SNR requirement to achieve certain BER in the presence of oscillator instabilities on AWGN & mobile radio channels. The modelled Wiener phase noise is generated for different 3dB bandwidths of noise spectrum. The simulation results shows that, the SNR required to achieve a bit rate of 10-2 in wavelet multiplexing is around 6dB lower as compared to FFT counterpart. The result also reveal that PAPR is also less, however wavelet multiplexing computational intensive
Direct synthesis of nanostructured V2O5 films using solution plasma spray approach for lithium battery applications
No full textMicrosturcutre Effects on Electrochemical Characteristics for Plasma Spray Deposited LiFePO4 Films
No full textThe electrochemical behavior of composite electrodes used in Li ion batteries is influenced by factors such as microstructural characteristics (e.g. particle size, crystallinity, porosity etc.) and composition. For optimal performance of electrodes these factors are of utmost concern and serve as motivation for research in this field. In this report, we investigated LiFePO4 films synthesized by a novel plasma spray deposition method, which has capability for direct deposition of LiFePO4 films with carbon. This enables electrode characterizations to be carried out at the film level, without recourse to steps involving powder material handling. In this report microstructure and electrochemical properties of LiFePO4 films were investigated to elucidate their unique characteristics. Our studies show that factors such as porosity and microstructure of the films affect the electrochemical properties. The mechanical compression and thermal annealing experiments are shown to affect the electrochemical characteristics of LiFePO4 films. We show that annealing treatment leads to a drastic improvement in impedance and charge-discharge capacities for the LiFePO4 films. These treatments could serve to improve the electrode properties of porous film based materials for Li ion batteries and help us develop new film based materials for energy storage applications
Single-walled nanotubes by the pyrolysis of acetylene-organometallic mixtures
No full textGas-phase pyrolysis of acetylene along with a metallocene or with a binary mixture of metallocenes in flowing Ar or Ar+H2 at 1100°C yields single-walled carbon nanotubes. Pyrolysis of Fe(CO)5-acetylene mixtures in Ar at 1100°C also gives single-walled nanotubes. The diameter of the nanotubes is generally around 1 nm, showing thereby that on pyrolysis under the dilute conditions employed, the organometallic precursors give rise to very fine metal particles essential for the formation of such nanotubes
The Origin of Long-Period Lattice Spacings Observed in Iron-Carbide Nanowires Encapsulated by Multiwall Carbon Nanotubes
No full textThe authors acknowledge financial support from the SouthEast Physics Network and from the Engineering and Physical Sciences Research Council
Mapping of Global Publications on Artificial Intelligence: A Scientometric Analysis
No full textObjective: Artificial Intelligence (AI) has emerged as an innovative technology with the potential to revolutionize various industries. This study uses a scientometric methodology to evaluate the current research in artificial intelligence comprehensively. Design/Methodology/Approach: This study employed scientometric indicators to identify key trends, patterns, and research gaps in the existing literature. A comprehensive dataset of 1803 academic papers on artificial intelligence, published between 2003 and 2023, was assembled and assessed using the Scopus database. Various scientometric instruments, such as Biblioshiny and VOSviewer, have significantly improved this study. Results/Discussion: The study's results provide substantial insights. The research indicated that the peak number of publications occurred in 2021, totaling 601 (33.33%), with the predominant document type being articles at 771 (42.76%), succeeded by conference articles at 428 (23.74%). Journal articles demonstrated the highest prevalence among various publication categories, comprising 771 (42.76%), followed by conference papers at 428. The United States emerged as the foremost contributor with 405 articles, followed by India with 234 publications. Conclusions: The University of Birmingham emerged as the most distinguished affiliation, boasting 17 publications and 1,670 citations. The "Lecture Notes in Computer Science (including the subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)" series is the most productive source, releasing 100 papers, of which 97 were cited. The author, Liu Xiaoxuan, is a distinguished figure with an h-index of 13 and a g-index of 14. Contribution: To assess the state of AI scientific production in the period 2021-2023, to contribute to scientific research
Encapsulated Molecules in Carbon Nanotubes: Structure and Properties
No full textWe encapsulate a number of fullerenes inside single-walled carbon nanotubes (SWNTs) including La2@C80 and ErxSc3-xN@C80(x=0-3). The structural properties of these nanoscopic hybrid materials are described using high resolution transmission electron microscopy and electron diffraction. It is found that the encapsulated fullerenes selfassemble into long, one-dimensional chains. The thermal stability of these supramolecular assemblies are studied and large variations are found. The behavior is nominally consistent with the mass of the encapsulated metallofullerenes
Production of bundles of aligned carbon and carbon–nitrogen nanotubes by the pyrolysis of precursors on silica-supported iron and cobalt catalysts
No full textPyrolysis of acetylene over iron or cobalt nanoparticles well dispersed on silica substrates gives copious yields of aligned carbon nanotube bundles. By carrying out the pyrolysis of pyridine over these catalyst surfaces, good quantities of aligned carbon–nitrogen nanotube bundles have been produced. The composition of the carbon–nitrogen nanotubes varies between C10N and C33N, depending on the catalyst
