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

Performance analysis with network-enhanced complexities: On fading measurements, event-triggered mechanisms, and cyber attacks

Copyright © 2014 Derui Ding et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Nowadays, the real-world systems are usually subject to various complexities such as parameter uncertainties, time-delays, and nonlinear disturbances. For networked systems, especially large-scale systems such as multiagent systems and systems over sensor networks, the complexities are inevitably enhanced in terms of their degrees or intensities because of the usage of the communication networks. Therefore, it would be interesting to (1) examine how this kind of network-enhanced complexities affects the control or filtering performance; and (2) develop some suitable approaches for controller/filter design problems. In this paper, we aim to survey some recent advances on the performance analysis and synthesis with three sorts of fashionable network-enhanced complexities, namely, fading measurements, event-triggered mechanisms, and attack behaviors of adversaries. First, these three kinds of complexities are introduced in detail according to their engineering backgrounds, dynamical characteristic, and modelling techniques. Then, the developments of the performance analysis and synthesis issues for various networked systems are systematically reviewed. Furthermore, some challenges are illustrated by using a thorough literature review and some possible future research directions are highlighted.This work was supported in part by the National Natural Science Foundation of China under Grants 61134009, 61329301, 61203139, 61374127, and 61374010, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany

Integrating vocational training in culinary arts and Islamic studies at juvenile rehabilitation centres: Malaysian experience

The Juvenile Rehabilitation Centres (JRC) in Malaysia aims to provide shelter, counselling and skills training to juveniles specifically for those who wish to transform themselves from the regrettable misdeeds they have committed. At JRCs, an integrated Culinary Vocational Training and Islamic education forms part of their training curriculum. The skills acquired should enable trainees to secure jobs upon completion of training. However, there are some training institutions that lack systematic training structures resulting in trainees becoming less skilful in both vocational and Islamic education. The objective of this research is to identify the effectiveness of an integrated Culinary and Islamic Education curriculum implemented at JRCs in Malaysia. This is a descriptive survey and data was obtained using questionnaire and interview. Respondents comprised 92 trainees, four managers, four culinary trainers and four Islamic education teachers, all from four different JRCs. The findings show that the trainees are happy with their trainings that brought about positive effects for them. Some suggestions have been made to provide improvements in the implementation of the course among them the inclusion of prayers in the Islamic education syllabus

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

Coherent Topological Charge Structure in CPN−1CP^{N-1} Models and QCD

In an effort to clarify the significance of the recent observation of long-range topological charge coherence in QCD gauge configurations, we study the local topological charge distributions in two-dimensional $CP^{N-1}$ sigma models, using the overlap Dirac operator to construct the lattice topological charge. We find long-range sign coherence of topological charge along extended one-dimensional structures in two-dimensional spacetime. We discuss the connection between the long range topological structure found in $CP^{N-1}$ and the observed sign coherence along three-dimensional sheets in four-dimensional QCD gauge configurations. In both cases, coherent regions of topological charge form along membrane-like surfaces of codimension one. We show that the Monte Carlo results, for both two-dimensional and four-dimensional gauge theory, support a view of topological charge fluctuations suggested by Luscher and Witten. In this framework, the observed membranes are associated with boundaries between ``k-vacua,'' characterized by an effective local value of $\theta$ which jumps by $\pm 2\pi$ across the boundary.Comment: 26 page

A Review on Reconfigurable Low Pass Bandstop Filter Based on Technology, Method and Design

Abstract-Reconfigurable filter technology is in robustness development. Due on the tunable and reconfigurable capability will contribute a various advantages in wireless applications. This tuning selectivity consist a numerous method, for example using varactor, micromachines, and PINdiodes.This review paper discussed PIN diodes as a switching element. The design and development of different types of switching element were then described. This paper presents of reconfigurable low pass bandstop filter WLAN, UWB bands applications for the past few years that operatedbetween1 to 5.6GHz. Most of the studies were focus on Chebyshev filter because of the excellent selectivity and the response is easy to be analyzed. Different types of method have been introduced in reconfigurable low pass bandstop filter, design and performance of the filter will then be compared

A Review on Reconfigurable Low Pass Bandstop Filter Based on Technology, Method and Design

Abstract-Reconfigurable filter technology is in robustness development. Due on the tunable and reconfigurable capability will contribute a various advantages in wireless applications. This tuning selectivity consist a numerous method, for example using varactor, micromachines, and PINdiodes.This review paper discussed PIN diodes as a switching element. The design and development of different types of switching element were then described. This paper presents of reconfigurable low pass bandstop filter WLAN, UWB bands applications for the past few years that operatedbetween1 to 5.6GHz. Most of the studies were focus on Chebyshev filter because of the excellent selectivity and the response is easy to be analyzed. Different types of method have been introduced in reconfigurable low pass bandstop filter, design and performance of the filter will then be compared