3,661 research outputs found
Algorithms for fitting cylindrical objects to sparse range point clouds for rapid workspace modeling
Asymmetric scattering and non-orthogonal mode patterns in optical micro-spirals
Quasi-bound states in an open system do in general not form an orthogonal and
complete basis. It is, however, expected that the non-orthogonality is weak in
the case of well-confined states except close to a so-called exceptional point
in parameter space. We present numerical evidence showing that for passive
optical microspiral cavities the parameter regime where the non-orthogonality
is significant is rather broad. Here we observe almost-degenerate pairs of
well-confined modes which are highly non-orthogonal. Using a non-Hermitian
model Hamiltonian we demonstrate that this interesting phenomenon is related to
the asymmetric scattering between clockwise and counterclockwise propagating
waves in the spiral geometry. Numerical simulations of ray dynamics reveal a
clear ray-wave correspondence.Comment: 8 pages, 10 figure
Long Memory and FIGARCH Models for Daily and High Frequency Commodity Prices
Daily futures returns on six important commodities are found to be well described as FIGARCH fractionally integrated volatility processes, with small departures from the martingale in mean property. The paper also analyzes several years of high frequency intra day commodity futures returns and finds very similar long memory in volatility features at this higher frequency level. Semi parametric Local Whittle estimation of the long memory parameter supports the conclusions. Estimating the long memory parameter across many different data sampling frequencies provides consistent estimates of the long memory parameter, suggesting that the series are self-similar. The results have important implications for future empirical work using commodity price and returns data.Commodity returns, Futures markets, Long memory, FIGARCH
Intrinsic Electrical Transport Properties of Monolayer Silicene and MoS2 from First Principles
The electron-phonon interaction and related transport properties are
investigated in monolayer silicene and MoS2 by using a density functional
theory calculation combined with a full-band Monte Carlo analysis. In the case
of silicene, the results illustrate that the out-of-plane acoustic phonon mode
may play the dominant role unlike its close relative - graphene. The small
energy of this phonon mode, originating from the weak sp2 bonding between Si
atoms, contributes to the high scattering rate and significant degradation in
electron transport. In MoS2, the longitudinal acoustic phonons show the
strongest interaction with electrons. The key factor in this material appears
to be the Q valleys located between the {\Gamma} and K points in the first
Brillouin zone as they introduce additional intervalley scattering. The
analysis also reveals the potential impact of extrinsic screening by other
carriers and/or adjacent materials. Subsequent decrease in the actual
scattering rate can be drastic, warranting careful consideration. Finally, the
effective deformation potential constants are extracted for all relevant
intrinsic electron-phonon scattering processes in both materials
Phase Response Curves of Coupled Oscillators
Many real oscillators are coupled to other oscillators and the coupling can
affect the response of the oscillators to stimuli. We investigate phase
response curves (PRCs) of coupled oscillators. The PRCs for two weakly coupled
phase-locked oscillators are analytically obtained in terms of the PRC for
uncoupled oscillators and the coupling function of the system. Through
simulation and analytic methods, the PRCs for globally coupled oscillators are
also discussed.Comment: 5 pages 4 figur
Pattern Formation in a Two-Dimensional Array of Oscillators with Phase-Shifted Coupling
We investigate the dynamics of a two-dimensional array of oscillators with
phase-shifted coupling. Each oscillator is allowed to interact with its
neighbors within a finite radius. The system exhibits various patterns
including squarelike pinwheels, (anti)spirals with phase-randomized cores, and
antiferro patterns embedded in (anti)spirals. We consider the symmetry
properties of the system to explain the observed behaviors, and estimate the
wavelengths of the patterns by linear analysis. Finally, we point out the
implications of our work for biological neural networks
The Factors of Influence towards Knowledge Sharing Among TVET Educators: A Study on TVET Educators within Hulu Langat District
Similar to other higher education institutions, knowledge sharing among highly skilled instructors and other instructors is important in improving the quality of training and skills development in the Technical Vocational Education and Training (TVET) institutions. In this borderless world, information technology enables knowledge sharing activities to be carried out more efficiently, quickly and widely. Understanding the influencing factors of knowledge sharing activities in TVET institutions is important since a number of failures have been reported due to the lack of awareness in contributing new knowledge. Therefore, this study is conducted to identify the factors that influence knowledge sharing activities among instructors in TVET institutions and to propose a framework to the knowledge sharing activities. A quantitative study involving 96 respondents was conducted and the data that was analysed using multiple regression analysis found that there are four (4) factors that contribute to knowledge sharing activities in TVET institutions: organizational, content, cooperation and technological. The proposed framework is expected to assist in the development of a repository of knowledge sharing among instructors in TVET institutions
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