139,719 research outputs found
Direct numerical simulation of 'short' laminar separation bubbles with turbulent reattachment
No full textDirect numerical simulation of the incompressible Navier–Stokes equations is used to study flows where laminar boundary-layer separation is followed by turbulent reattachment forming a closed region known as a laminar separation bubble. In the simulations a laminar boundary layer is forced to separate by the action of a suction profile applied as the upper boundary condition. The separated shear layer undergoes transition via oblique modes and [Lambda]-vortex-induced breakdown and reattaches as turbulent flow, slowly recovering to an equilibrium turbulent boundary layer. Compared with classical experiments the computed bubbles may be classified as ‘short’, as the external potential flow is only affected in the immediate vicinity of the bubble. Near reattachment budgets of turbulence kinetic energy are dominated by turbulence events away from the wall. Characteristics of near-wall turbulence only develop several bubble lengths downstream of reattachment. Comparisons are made with two-dimensional simulations which fail to capture many of the detailed features of the full three-dimensional simulations. Stability characteristics of mean flow profiles are computed in the separated flow region for a family of velocity profiles generated using simulation data. Absolute instability is shown to require reverse flows of the order of 15–20%. The three-dimensional bubbles with turbulent reattachment have maximum reverse flows of less than 8% and it is concluded that for these bubbles the basic instability is convective in nature
5.6 kW peak power, nanosecond pulses at 274 nm from a frequency quadrupled Yb-doped fiber MOPA
No full textDataset for the paper:
He, J, Lin, D, Xu, L, Beresna, M, Zervas, M, Alam, S-U & Brambilla, G (2018) '5.6 kW peak power, nanosecond pulses at 274 nm from a frequency quadrupled Yb-doped fiber MOPA' in Optics Express
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Interdependent multi-issue negotiation for energy exchange in remote communities
No full textWe present a novel negotiation protocol to facilitate energy exchange between off-grid homes that are equipped with renewable energy generation and electricity storage. Our protocol imposes restrictions over negotiation such that it reduces the complex interdependent multi-issue negotiation to one where agents have a strategy profile in subgame perfect Nash equilibrium. We show that our negotiation protocol is tractable, concurrent, scalable and leads to Pareto-optimal outcomes in a decentralised manner. We empirically evaluate our protocol and show that, in this instance, a society of agents can (i) improve the overall utilities by 14% and (ii) reduce their overall use of the batteries by 37
Two-dimensional MoS2 negative capacitor transistors for enhanced (super-Nernstian) signal-to-noise performance of next-generation nano biosensors
No full textThe detection of biomolecules by a Field Effect Transistor-based biosensor (BioFET) is dictated by the sensor's intrinsic Signal-to-Noise Ratio (SNR). The detection limit of a traditional BioFET is fundamentally limited by biomolecule diffusion, charge screening, linear charge to surface-potential transduction, and Flicker noise. In this letter, we show that the recently introduced class of transistors called negative capacitor field effect transistors offers nonlinear charge transduction and suppression of Flicker noise to dramatically improve the SNR over classical Boltzmann sensors. We quantify the SNR improvement (approximately two orders of magnitude higher than a classical Si-nanowire biosensor) by interpreting the experimental results associated with the signal and noise characteristics of 2D MoS2-based transistors. The proposed Negative Capacitor BioFET (NC-BioFET) will motivate experimentalists to combine two well-established technologies to achieve high SNR (and to improve the detection limit), fundamentally unachievable by any other sensor technology
Recommendation domains for pond aquaculture: country case study: development and status of freshwater aquaculture in Bangladesh
No full textThis report is an output of the project ôDetermination of high-potential aquaculture development areas and impact in Africa and Asiaö. This monograph is the case study for Bangladesh. Written in three parts, it describes the historical background, practices, stakeholder profiles, production levels, economic and institutional environment, policy issues, and prospects for aquaculture in the country. First, it documents the history and current status of the aquaculture in the country. Second, it assesses the technologies and approaches that either succeeded or failed to foster aquaculture development and discusses why. Third, it identifies the key reasons for aquaculture adoption.Freshwater aquaculture, Economic analysis, Trade, Ecosystems, Pond culture, Fish consumption, Food security, Policies, Regulations, Legislation, Socioeconomic aspects, Yield, Bangladesh,
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Pump it up - Developing a pro-poor mobile pump market
No full textBadrul Alam, Noel P. Magor And Paul Van Mel
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