14,181 research outputs found
Cultural Values and Cross-cultural Video Consumption on YouTube
Video-sharing social media like YouTube provide access to diverse cultural
products from all over the world, making it possible to test theories that the
Web facilitates global cultural convergence. Drawing on a daily listing of
YouTube's most popular videos across 58 countries, we investigate the
consumption of popular videos in countries that differ in cultural values,
language, gross domestic product, and Internet penetration rate. Although
online social media facilitate global access to cultural products, we find this
technological capability does not result in universal cultural convergence.
Instead, consumption of popular videos in culturally different countries
appears to be constrained by cultural values. Cross-cultural convergence is
more advanced in cosmopolitan countries with cultural values that favor
individualism and power inequality
Evaluation of a fuzzy-expert system for fault diagnosis in power systems
A major problem with alarm processing and fault diagnosis in power systems is the reliance on the circuit alarm status. If there is too much information available and the
time of arrival of the information is random due to weather conditions etc., the alarm activity is not easily interpreted by system operators. In respect of these problems, this thesis sets out the work that has been carried out to design and evaluate a diagnostic tool which assists power system operators during a heavy period of alarm activity in condition monitoring. The aim of employing this diagnostic tool is to monitor and raise uncertain alarm information for the system operators, which serves a proposed solution for restoring such faults.
The diagnostic system uses elements of AI namely expert systems, and fuzzy logic that incorporate abductive reasoning. The objective of employing abductive reasoning is to optimise an interpretation of Supervisory Control and Data Acquisition (SCADA) based uncertain messages when the SCADA based messages are not satisfied with simple logic
alone. The method consists of object-oriented programming, which demonstrates reusability, polymorphism, and readability. The principle behind employing objectoriented
techniques is to provide better insights and solutions compared to conventional artificial intelligence (Al) programming languages. The characteristics of this work involve the development and evaluation of a fuzzy-expert
system which tries to optimise the uncertainty in the 16-lines 12-bus sample power system. The performance of employing this diagnostic tool is assessed based on consistent data acquisition, readability, adaptability, and maintainability on a PC. This diagnostic tool enables operators to control and present more appropriate interpretations effectively rather than a mathematical based precise fault identification when the mathematical
modelling fails and the period of alarm activity is high.
This research contributes to the field of power system control, in particular Scottish Hydro-Electric PLC has shown interest and supplied all the necessary information and data. The AI based power system is presented as a sample application of Scottish Hydro-Electric and KEPCO (Korea Electric Power Corporation)
Numerical Study on Interactional Aerodynamics of a Quadcopter in Hover with Overset Mesh in OpenFOAM
Interactional aerodynamics of a quadcopter in hover is numerically
investigated in this study. The main objective is to understand major flow
structures associated with unsteady airloads on multirotor aircraft. The
overset mesh approach is used to resolve flow structures in unsteady simulation
using the flow solver OpenFOAM. The current computational study demonstrates
that aerodynamic interaction between quadcopter components strongly affects the
rotor wake, generating interesting vortical structures. Multiple rotors in
close proximity generate -shaped vortical structures merged from
rotor-tip vortices. The fuselage of the current quadcopter deflects the wake
flow of the four rotors towards the center of the vehicle. Such interactional
aerodynamics, i.e., rotor-rotor and rotor-fuselage interaction, varies the
inflow condition of a rotor blade during the rotor revolution. Therefore, the
quadcopter experiences unsteady airloads per rotor revolution. Our study
indicates that a typical quadcopter would experience 8/rev thrust variations,
which are a combined outcome from 4/rev thrust variations on the rotor and
2/rev fluctuations on the fuselage. The current understanding of interactional
aerodynamics could help to design reliable and efficient multicopter aircraft
Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts
We have investigated the electrical Hanle effect with magnetic fields applied
at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect,
OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal
measurement scheme. The electrical oblique Hanle signals obtained in
CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes
depending on the spin lifetime of the host SC. Notably, at moderate magnetic
fields, the asymptotic values of the oblique Hanle signals (in both contacts)
are consistently reduced by a factor of cos^2({\theta}) irrespective of the
bias current and temperature. These results are in good agreement with
predictions of the spin precession and relaxation model for the electrical
oblique Hanle effect. At high magnetic fields where the magnetization of CoFe
is significantly tilted from the film plane to the magnetic field direction, we
find that the observed angular dependence of voltage signals in the CoFe/MgO/Si
and CoFe/MgO/Ge contacts are well explained by the OHE, considering the
misalignment angle between the external magnetic field and the magnetization of
CoFe.Comment: 19 pages, 8 figure
Quantum Key Distribution with Blind Polarization Bases
We propose a new quantum key distribution scheme that uses the blind
polarization basis. In our scheme the sender and the receiver share key
information by exchanging qubits with arbitrary polarization angles without
basis reconciliation. As only random polarizations are transmitted, our
protocol is secure even when a key is embedded in a not-so-weak coherent-state
pulse. We show its security against the photon number splitting attack and the
impersonation attack.Comment: Security has been improved upon referee's comment. 4 pages and 2
figure
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