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Dispersion-engineered silicon nitride waveguides for mid-infrared supercontinuum generation covering the wavelength range 0.8-6.5 mu m
We numerically demonstrate the generation of a mid-infrared supercontinuum (SC) through the design of an on-chip complementary metal oxide semiconductor (CMOS) compatible 10-mm-long air-clad rectangular waveguide made using stoichiometric silicon nitride (Si 3 N 4 ) as the core and MgF 2 glass as its lower cladding. The proposed waveguide is optimized for pumping in both the anomalous and all-normal dispersion regimes. A number of waveguide geometries are optimized for pumping at 1.55 μ m with ultrashort pulses of 50-fs duration and a peak power of 5 kW. By initially keeping the thickness constant at 0.8 μ m, four different structures are engineered with varying widths between 3 μ m and 6 μ m. The largest SC spectral evolution covering a region of 0.8 μ m to beyond 6.5 μ m could be realized by a waveguide geometry with a width of 3 μ m. Numerical analysis shows that increasing width beyond 3 μ m by fixing thickness at 0.8 μ m results in a reduction of the SC extension in the long wavelength side. However, the SC spectrum can be enhanced beyond 6.5 μ m by increasing the waveguide thickness beyond 0.9 μ m with the same peak power and pump source. To the best of our knowledge, this is first time report of a broad SC spectral evolution through numerical demonstration in the mid-infrared region by the silicon nitride waveguide. In the case of all-normal dispersion pumping, a flatter SC spectra can be predicted with the same power and pump pulse but with a reduced bandwidth spanning 950–2100 nm
Ab-initio study of the bandgap engineering of Al(1-x)Ga(x)N for optoelectronic applications
A theoretical study of Al(1-x)Ga(x)N, based on full-potential linearized
augmented plane wave method, is used to investigate the variations in the
bandgap, optical properties and non-linear behavior of the compound with the
variation of Ga concentration. It is found that the bandgap decreases with the
increase of Ga in Al(1-x)Ga(x)N. A maximum value of 5.5 eV is determined for
the bandgap of pure AlN which reaches to minimum value of 3.0 eV when Al is
completely replaced by Ga. The static index of refraction and dielectric
constant decreases with the increase in bandgap of the material, assigning a
high index of refraction to pure GaN when compared to pure AlN. The refractive
index drops below 1 for photon energies larger than 14 eV results group
velocity of the incident radiation higher than the vacuum velocity of light.
This astonishing result shows that at higher energies the optical properties of
the material shifts from linear to non-linear. Furthermore, frequency dependent
reflectivity and absorption coefficients show that peak value of the absorption
coefficient and reflectivity shifts towards lower energy in the UV spectrum
with the increase in Ga concentration. This comprehensive theoretical study of
the optoelectronic properties of the alloys is presented for the first time
which predicts that the material can be effectively used in the optical devices
working in the visible and UV spectrum.Comment: 18 pages, 7 figure
Event by Event Analysis of High Multiplicity Events Produced in 158 A GeV/c 208 Pb- 208 Pb Collisions
An extensive analysis of individual high multiplicity events produced in 158
A GeV /c 208Pb- 208Pb collisions is carried by adopting different methods to
examine the anomalous behavior of these rare events. A method of selecting the
events with densely populated narrow regions or spikes out of a given sample of
collision events is discussed.Employing this approach two events with large
spikes in their eta- and phi- distributions are selected for further analysis.
For the sake of comparison, another two events which do not exhibit such spikes
are simultaneously analyzed. The findings suggest that the systematic studies
of particle density fluctuations in one- and two-dimensional phase-spaces and
comparison with those obtained from the studies of correlation free Monte Carlo
events, would be useful for identifying the events with large dynamical
fluctuations. Formation of clusters or jet like phenomena in multihadronic
final states in individual events is also discussed and the experimental
findings are compared with the independent particle emission hypothesis by
carrying out Monte Carlo simulations
Market Power and Efficiency of Islamic Banking and Conventional Banking in Indonesia
ASEAN Economic Community (AEC) of banking industry requires both Islamic and conventional banking to improve their efficiency because the competition in banking market industry will be more intense. Therefore, this study aims to identify the type of hyphotesis of industrial organization which exists in Islamic and conventional banks in order to investigate their readiness for AEC. The research sampling consists of 10 Islamic banks and 10 conventional banks from January 2009 to December 2016. To measure x-efficiency and scale efficiency, this research uses Data Envelopment Analysis (DEA). Meanwhile, the concentration is measured by Lerner index. The hypothesis is tested by using panel regression. The result shows SCP (Structure-Conduct-Performance) hypothesis is closely applied to Islamic and conventional banks because market concentration significantly influences profitability. RMP (Relative Market Power) hypothesis is also closely applied to Islamic and conventional banking, this indicates Indonesian banking has market power in determining prices and this condition makes the profit higher. RES (Relative Efficiency Structure) and SES (Scale Efficiency Structure) hypothesis do not exist in both conventional and Islamic banks because x-efficiency and scale efficiency do not affect profitability, concentration, and market share simultaneously. Market power and efficiency researches are commonly conducted in conventional banking, however there are only a few research in Islamic banking area. The novelty of this study is the comparison between conventional and Islamic banking in the term of market structure and efficiency
Complexity in manufacturing systems and its measures: a literature review
Complexity in manufacturing systems still remains a challenge and leads to operational issues and increased production cost. In this paper, drivers of complexity and typical symptoms of complex manufacturing systems are identified. A comprehensive review of studies published within the last two decades to assess manufacturing system complexity are presented. The key contributions of this review are: 1) a classification of complexity assessment methods based on perceived complexity symptoms; 2) a comprehensive review of assessment methods with cross-evaluation to identify appropriate use based on available data; 3) recommendations for the wider academic and industrial community, based on research trends identified in the literature, as to how complexity assessment should be addressed in the future. It is concluded that the assessment of complexity is necessary so that it can be controlled effectively, however the industry suffers from a lack of practical tools to support in this endeavour
A Lightweight Approach for Human Factor Assessment in Virtual Assembly Designs: An Evaluation Model for Postural Risk and Metabolic Workload
© 2016 The Authors. The assessment and optimisation of postural stress and physical fatigue can be challenging and is typically conducted only after the design of manual operations has been finalised. However early assessment of manual operations and identification of critical factors that are deemed outside of an appropriate envelope can avoid the time and costs often associated with re-designing machines and layout for operator work processes. This research presents a low cost software solution based on a simplified skeleton model that uses operator position and workload data extracted from a simulation model used for virtual manufacturing process planning. The developed approach aims to assess postural stress and physical fatigue scores of assembly operations, as they are being designed and simulated virtually. The model is based on the Automotive Assembly Worksheet and the Garg's metabolic rate prediction model. The proposed research focuses on the integration of virtual process planning, ergonomic and metabolic analysis tools, and on automating human factor assessment to enable optimisation of assembly operations and workload capabilities at early design stage
Design Evaluation of Automated Manufacturing Processes Based on Complexity of Control Logic
Complexity continues to be a challenge in manufacturing systems, resulting in ever-inflating costs, operational issues and increased lead times to product realisation. Assessing complexity realizes the reduction and management of complexity sources which contributes to lowering associated engineering costs and time, improves productivity and increases profitability. This paper proposes an approach for evaluating the design of automated manufacturing processes based on the structural complexity of the control logic. Six complexity indices are introduced and formulated: Coupling, Restrictiveness, Diameter, Branching, Centralization, and Uncertainty. An overall Logical Complexity Index (CL) which combines all of these indices is developed and demonstrated using a simple pick and place automation process. The results indicate that the proposed approach can help design automation logics with the least complexity and compare alternatives that meet the requirements during initial design stages
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