We have made off-resonant nonlinear optical measurements of PTS polydiacetylene in a Fabry-Perot cavity. The measurement was made by a pump-probe technique using 90 ps pulses at 1.06 mu m wavelength. The change in tra...
We have made off-resonant nonlinear optical measurements of PTS polydiacetylene in a Fabry-Perot cavity. The measurement was made by a pump-probe technique using 90 ps pulses at 1.06 mu m wavelength. The change in transmission at specific bias points on the F-P fringe, was measured as a function of time delay between the pump and probe. Large (similar to 50%) changes in transmission with a pulse-with-limited response time, were observed at low optical intensities. The magnitude of n(2) as measured (similar to 10(-5) cm(2)/MW) and the negative sign are consistent with our Z-scan measurement of PTS at this wavelength. The results of the measurement on the F-P cavity clearly demonstrate possibilities of applications of PTS in ultrafast (sub-picosecond) all-optical switching and logic operations using this device geometry. This is the first time that all-optical switching with time resolution has been demonstrated for an organic material.
Computer programming has become an essential technical proficiency needed by companies especially within the Information Technology industry. To prepare graduates with the required skills and knowledge, many universit...
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ISBN:
(纸本)9781728114606
Computer programming has become an essential technical proficiency needed by companies especially within the Information Technology industry. To prepare graduates with the required skills and knowledge, many university courses have integrated modules that teach students such concepts. However, learning programming languages was found to be challenging to students as concepts are abstract, making it difficult for students to understand. In order to address such challenges and to innovate from traditional learning techniques, tangible user interfaces (TUI) could potentially be used to enhance learning experience. However, limited work has been done to investigate the use of TUI for students to learn the programming languages. Due to this limitation, the usability of such systems has not been well studied even though this quality attribute is important to investigate so as to improve adoption of systems by end users. This study delves into the usability of a TUI system for teaching basic java programming concepts. To achieve this purpose, a prototype was developed using Processing and ReacTIVision. The usability of the proposed prototype was evaluated through application of the System Usability Scale. Results revealed that the system is acceptable on the scale used although different limitations were identified.
Building time series models for ecological systems that can be physically interpreted is important both for understanding the dynamics of these natural systems and the development of decision support systems. This wor...
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Building time series models for ecological systems that can be physically interpreted is important both for understanding the dynamics of these natural systems and the development of decision support systems. This work describes the application of an evolutionary computation framework for the discovery of predictive equations and rules for phytoplankton abundance in freshwater lakes from time series data. The suggested framework evolves several different equations and rules, based on limnological and climate variables. The results demonstrate that non-linear processes in natural systems may be successfully modelled through the use of evolutionary computation techniques. Further, it shows that a grammar based genetic programming system may be used as a tool for exploring the driving processes underlying freshwater system dynamics. (C) 2001 Elsevier Science B.V. All rights reserved.
In this paper, we propose a defected core hexagonal lattice structure photonic crystal fiber (PCF) design which has optical properties like high nonlinearity, high birefringence and increased negative dispersion in th...
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ISBN:
(纸本)9781467366762
In this paper, we propose a defected core hexagonal lattice structure photonic crystal fiber (PCF) design which has optical properties like high nonlinearity, high birefringence and increased negative dispersion in the wavelength range 1300 nm- 1800 nm. The full vectorial finite element method is used to characterize the proposed design. An anisotropic perfectly matched layer is used to accurately account for the confinement loss. It has been shown theoretically that the proposed PCF exhibits high birefringence of 3.22 x 10(-2) with high nonlinear coefficient of 39.2 W(-1)km(-1) and negative dispersion coefficient of -346 ps/nm/km at the wavelength of 1550 nm. The variation of structural parameters is also studied to determine the tolerance of the fabrication. Due to the novel optical characteristics, the proposed PCF can be considered as a useful candidate in supercontinuum generation, dispersion compensation and sensing applications.
The methods of nonlinear adaptation based on an analytical design of aggregated regulators and modal control are discussed for solving the problem of nonlinear control over a robotic arm operating under the conditions...
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We have recently concentrated our theoretical effort on two methods of producing submillimeter radiation with intense relativistic electron beams. The cyclotron maser instability and the magneto-resonant scattering of...
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The concept of robustness as the probability mass of a design-dependent set has been introduced in the literature. Optimization of robustness can be seen as finding the design that has the highest robustness. The refe...
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The concept of robustness as the probability mass of a design-dependent set has been introduced in the literature. Optimization of robustness can be seen as finding the design that has the highest robustness. The reference method for estimating the robustness is the Monte Carlo (MC) simulation, and the drawback for its direct use in nonlinear optimization is the lack of derivative information and the appearance of discontinuities. An alternative for MC is presented, called the smoothed Monte Carlo estimation. It is proved that the resulting estimate function is made continuous in relevant design points and facilitates the use of standard nonlinear optimization algorithms. The whole procedure is illustrated numerically.
We consider a generalized Ornstein-Uhlenbeck process described by a nonlinear Fokker-Planck equation related to the one-parametric, nonextensive Gaussian entropy, which is a special case of the two-parametric Sharma-M...
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We consider a generalized Ornstein-Uhlenbeck process described by a nonlinear Fokker-Planck equation related to the one-parametric, nonextensive Gaussian entropy, which is a special case of the two-parametric Sharma-Mittal entropy. We derive the entire hierarchy of distribution functions for that process and, in doing so, derive a complete description of a stochastic process related to a nonextensive entropy measure. (C) 2004 Elsevier B.V. All rights reserved.
This work proposes extensions to Wubby (a device-level software platform for IoT devices, a technology developed by Econais A.E.) to support wireless modules for mobile networks (4G / LTE-A, and also supporting the fo...
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ISBN:
(纸本)9783319676364;9783319676357
This work proposes extensions to Wubby (a device-level software platform for IoT devices, a technology developed by Econais A.E.) to support wireless modules for mobile networks (4G / LTE-A, and also supporting the forthcoming 5G). The proposed extension leverages the use of such modules, as it allows easy programming and existing code re-use. It thus adds a compatibility layer across the different modules as it a common set of classes for the wireless modules. The system can be used to support the networking aspects of a variety of IoT applications, including applications for Smart Cities, using a variety of IoT devices. This work suggests such a case focusing on air quality monitoring.
The performance and application of Active Power Filter (APF) in power system is closely linked to the control strategy. The paper proposes a novel nonlinear passivity-based algorithm for APF based on Euler-Lagrange (E...
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