725 research outputs found
Review—Group III-Nitride-Based Ultraviolet Light-Emitting Diodes: Ways of Increasing External Quantum Efficiency
No full textThere is a rapidly growing demand for highly efficient ultraviolet (UV) light sources for a wide variety of applications. In particular, state-of-the-art AlGaN deep UV light-emitting diodes (DUV LEDs) exhibit inadequately low external quantum efficiencies (EQEs). The low efficiencies are attributed to the inherent material properties of high-Al-content AlGaN including strained epitaxial layers, low carrier concentrations, and strong transverse magnetic (TM)-polarized light emission. Extensive efforts have been made to tackle these challenging issues and technological developments have been achieved and enabled the fabrication of reasonable EQE LEDs. In this review, recent advances in the growth of high-quality AlGaN epitaxial layers, transparent and reflective ohmic contacts, and light extraction for AlGaN-based UV LEDs are reviewed. (C) The Author(s) 2017. Published by ECS. All rights reserved.1117Nsciescopu
Network planning guidelines for DVB-T network rollout in Sri Lanka
No full textA dissertation submitted to the Department of Electronic and Telecommunication Engineering for the MSc in TelecommunicationThere has been a clear prospect internationally for some years that existing analogue
television broadcasting will be replaced by digital transmissions. Terrestrial digital
broadcasting offers a range of benefits in comparison to terrestrial analogue
broadcasting such as efficient spectrum utilization, improved audio & video quality,
portable & mobile reception capability etc. Sri Lanka being a developing country it is
high time to make timely entry to digital broadcast era, through establishment of
requisite infrastructure with a view to future dividends derivable from an advanced
digital infrastructure.Therefore the first section of this research discuss the inherent technical strengths of
digital terrestrial broadcasting and analyse candidate technology standards in digital
video broadcasting. further it propose the most suitable technology standard for DTT
rollout in Sri Lanka by analysing technical capabilities as well as degree of
compatibility with existing analog broadcast technology deployed in Sri LankaThe second section discuss the methodology for network planning, by proposing a set
of guidelines for efficient planning of digital video broadcast networks to achieve
nationwide coverage & thereby full access to viewers without any interruption during
DVB-T rollout by specifically analysing Sri Lankan deployment scenarios. Further it
has discussed various propagation models suitable for DVB-T network planning &
step by step guidelines for in-depth coverage estimations & network simulations by
optimizing DVB-T system parameters.
The final section of this research has in detail discussed DVB-T network
implementation issues in practical point of view by critically analysing factors such as
co-location of analog & digital transmission infrastructures, interference issues &
primary distribution architectures. Finally it provides set of recommendations, wherebroadcast network operators can follow when deploying DVB-T networks in SriLanka
Electrochemical Correlation Spectroscopy (ECS) in Nanofluidic Channels
No full textKavli Institute of NanoscienceApplied Science
The meaning of environmental control systems (ECS) for people with spinal cord injury: An occupational therapist explores an intervention
No full textEnvironmental Control Systems (ECS), enable people with high cervical Spinal Cord Injury (high SCI) to control and access everyday electronic devices. In Ireland, however, access for those who might benefit from ECS is limited. This study used a qualitative approach to explore the insider experience of an ECS starter-pack developed by the author, an occupational therapist. The primary research questions: what is it really like to live with ECS, and what does it mean to live with ECS, were explored using a phenomenological methodology conducted in three phases.
In Phase 1 fifteen people with high SCI met twice in four focus groups to discuss experiences and expectations of ECS. Thematic analysis (Krueger & Casey, 2000), influenced by the psychological phenomenological approach (Creswell, 1998), yielded three categories of rich, practical, phenomenological findings: ECS Usage and utility; ECS Expectations and The meaning of living with ECS.
Phase 1 findings informed Phase 2 which consisted of the development of a generic electronic assistive technology pack (GrEAT) that included commercially available constituents as well as short instructional videos and an information booklet. This second phase culminated in a one-person, three-week pilot trial.
Phase 3 involved a six person, 8-week trial of the GrEAT, followed by individual in-depth interviews. Interpretative Phenomenological Analysis IPA (Smith, Larkin & Flowers, 2009), aided by computer software ATLAS.ti and iMindmap, guided data analysis and identification of themes. Getting used to ECS, experienced as both a hassle and engaging, resulted in participants being able to Take back a little of what you have lost, which involved both feeling enabled and reclaiming a little doing.
The findings of this study provide substantial insights into what it is like to live with ECS and the meanings attributed to that experience. Several practical, real world implications are discussed
Increased Cycling Efficiency of Lithium Anodes in Dimethyl Sulfoxide Electrolytes For Use in Li-O-2 Batteries
No full textHigh lithium cycling efficiencies are required if a metal anode system is to be considered for use in Li-O-2 batteries. In this work electrolyte additives (0.3 M LiNO3 and 0.14 M VC) were used to increase the efficiency from 25 to 82.5% in the topical DMSO based electrolyte. Furthermore, we show that oxygen also acts to improve the cycling efficiency to 87%. This work highlights the importance of anode considerations in the development of metal O-2 batteries in alternative solvents (DMSO, Acetonitrile and DMA) and suggests realistic strategies for performance improvements. (C)The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved
Open access archiving and article citations within health services and policy research
Get PDFPromoting uptake of research findings is an objective common to those who fund, produce and publish health services and policy research. Open access (OA) is one method being employed to maximize impact. OA articles are online, free to access and use. This paper contributes to growing body of research exploring the “OA advantage” by employing an article-level analysis comparing citation rates for articles drawn from the same, purposively selected journals. We used a two-stage analytic approach designed to test whether OA is associated with (1) likelihood that an article is cited at all and (2) total number citations that an article receives, conditional on being cited at least once. Adjusting for potential confounders: number of authors, time since publication, journal, and article subject, we found that OA archived articles were 60% more likely to be cited at least once, and, once cited, were cited 29% more than non-OA articles
Communication-Anisotropic Electrochemical Etching of Porous Gallium Nitride by Sub-Bandgap Absorption Due to Franz-Keldysh Effect
No full textAnisotropic electrochemical etching of porous GaN structures by utilizing charge carriers generated by sub-bandgap absorption has been developed. Sub-bandgap light with a photon energy below the bandgap energy was transmitted through bulk GaN, but a certain type of photo-absorption additively occurred at the pore tip due to the Franz-Keldysh effect. The photocurrents observed when the reverse bias was applied to n-GaN were well reproduced by calculation taking into account the Frantz-Keldysh effect. The pore diameter was not changed that much, but the pore depth could be successfully controlled by the intensity and irradiation time of the sub-bandgap light. (C) The Author(s) 2019. Published by ECS
Application of a bottom-up approach for the analysis of rolling contact fatigue in the Dutch high speed line
No full textThis paper describes the use of big data analytics for understanding the Rolling Contact Fatigue (RCF) phenomena at the High Speed Line (HSL Zuid) in The Netherlands. The authors developed a data model to investigate the impacting parameters in train-track interaction. This has been done to gain more insightabout the circumstances under which RCF occurs and to conclude why some track sections are severely affected and others not.To evaluate the worst affected areas by RCF, the methodology proposes a bottom-up approach. By focusing on the worst affected sections with RCF, a set of characteristic parameter values are defined to describe different types of hotspots. Then, a comparison between the hotspots is performed. Themethodology has been applied using real-life data of the Dutch High-speed line, where certain sections had been heavily affected by RCF. Findings concluded that slow running traffic through curves on a highspeed line is likely to contribute to the appearance of RCF.Integral Design & ManagementRailway EngineeringMaterials and Environmen
A 19.8-mW Eddy-Current Displacement Sensor Interface with Sub-Nanometer Resolution
No full textThis paper presents an eddy-current sensor (ECS) interface intended for sub-nanometer (sub-nm) displacement sensing in hi-tech applications. The interface employs a 126-MHz excitation frequency to mitigate the skin effect, and achieve high resolution and stability. An efficient on-chip sensor offset compensation scheme is introduced which removes sensor-offset proportional to the standoff distance. To assist in the ratiometric suppression of noise and drift of the excitation oscillator, the ECS interface consists of a highly linear amplitude demodulation scheme that employs passive capacitors for voltage-to-current (V2I) conversion. Using a printed circuit board-based pseudo-differential ECS, stability tests were performed which demonstrated a thermal drift of <7.3 nm/°C and long-term drift of only 29.5 nm over a period of 60 h. The interface achieves an effective noise floor of 13.4 pm Hz which corresponds to a displacement resolution of 0.6 nm in a 2-kHz noise bandwidth. The ECS interface is fabricated in TSMC 0.18- μm CMOS technology and dissipates only 19.8 mW from a 1.8-V supply.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Potential environmental and human health risks caused by antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs) and emerging contaminants (ECs) from municipal solid waste (MSW) landfill
Get PDFFunding Information: The author V.T. would like to thank the Department of Science and Technology (DST), Science and Engineering Research Board (SERB), Government of India (file no ECR/2017/001809) for financial support. Publisher Copyright: © 2021 by the authors. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.The disposal of municipal solid waste (MSW) directly at landfills or open dump areas, without segregation and treatment, is a significant concern due to its hazardous contents of antibioticresistant bacteria (ARB), antibiotic resistance genes (ARGs), and metal resistance genes (MGEs). The released leachate from landfills greatly effects the soil physicochemical, biological, and groundwater properties associated with agricultural activity and human health. The abundance of ARB, ARGs, and MGEs have been reported worldwide, including MSW landfill sites, animal husbandry, wastewater, groundwater, soil, and aerosol. This review elucidates the occurrence and abundance of ARB, ARGs, and MRGs, which are regarded as emerging contaminants (ECs). Recently, ECs have received global attention because of their prevalence in leachate as a substantial threat to environmental and public health, including an economic burden for developing nations. The present review exclusively discusses the demands to develop a novel eco-friendly management strategy to combat these global issues. This review also gives an intrinsic discussion about the insights of different aspects of environmental and public health concerns caused due to massive leachate generation, the abundance of antibiotics resistance (AR), and the effects of released leachate on the various environmental reservoirs and human health. Furthermore, the current review throws light on the source and fate of different ECs of landfill leachate and their possible impact on the nearby environments (groundwater, surface water, and soil) affecting human health. The present review strongly suggests the demand for future research focuses on the advancement of the removal efficiency of contaminants with the improvement of relevant landfill management to reduce the potential effects of disposable waste. We propose the necessity of the identification and monitoring of potential environmental and human health risks associated with landfill leachate contaminants.Peer reviewe
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