Self-deflection of Three-dimensional Optical Beams by a Thin Nonlinear Layer with Saturable Dispersive and Absorptive Nonlinearity

Abstract

This paper describes self-deflection effects arising from the propagation of symmetric and asymmetric three-dimensional scalar optical beams through thin nonlinear layers. The model of nonlinearity used includes both saturation and absorption. In several cases, significant differences are observed between the present three-dimensional results and previous two-dimensional results based on the Kerr model of nonlinearity. Also, the existence of a large axial component of the self-deflected beam for a three-dimensional geometry against the absence of this component for a two-dimensional geometry is discussed.     

Holographically corrected telescope for high-bandwidth optical communications

We present a design for an optical data communications receiver-transmitter pair based on the holographic correction of a large diameter, poor-quality, reflecting primary mirror. The telescope has a narrow bandwidth (<0.1 nm) with good signal frequency isolation (>60 dB) and is scalable to meter-class apertures. We demonstrate the correction of a reflector telescope with over 2000 waves of aberration to diffraction-limited operation, capable of handling data transmission rates up to 100 GHz.     

Development and application of a novel class of hierarchicaltangential vector finite elements for electromagnetics

Tangential vector finite elements (TVFEs) overcome most of the shortcomings of node-based finite elements for electromagnetic simulations. For a triangular element, this paper proposes a class of hierarchical TVPEs that differ from traditional TVFEs. The hierarchical nature of the proposed TVFEs makes them ideally suited for employing an efficient selective field expansion (the lowest order TVFE employed within part of the computational domain and a higher order TVFE employed within the remaining part of the computational domain). This is an attractive feature not shared by nonhierarchical TVFEs for which a more traditional approach (the same TVFE employed throughout the computational domain) must be applied. For determining the scattering by composite cylinders, this paper argues that the performance (in terms of accuracy, memory, and, in most cases, CPU time) of the proposed class of hierarchical TVFEs when applying selective field expansion is superior to that of the lowest order TVFE and a traditional nonhierarchical TVFE. This is the case when an artificial absorber as well as a boundary integral is used for truncating the computational domain. A guideline is given as to how lowest and higher order TVFEs shall be combined for optimal performance of the proposed class of hierarchical TVFEs     

THERMODYNAMICS OF ASPHALTENE PRECIPITATION AND DISSOLUTION INVESTIGATION OF TEMPERATURE AND SOLVENT EFFECTS

Petroleum asphaltenes have been precipitated in solvent mixtures of n-heptane and toluene at various temperatures, likewise n-heptane asphaltenes have been dissolved in under similar conditions. This give added evidence to apparent hysteresis phenomenon between the two processes. The Asphaltenes have been characterized showing that although data is scattered convergence to certain structural parameters as incipient flocculation is approached. The asphaltenes are seen to consist of an associating and a non-associating part. The solubility of asphaltenes has been correlated/modelled using the Flory-Huggins equation using two different terms for the Flory parameter. A process for evaluation of best choice of solubility parameter and molar volume for the asphaltenes is proposed. Dissolution processes are seen to be best fitted by the equations. Based on these findings the asphaltenes are proposed to be formed by a colloidal and a true solution part.     

美国核工业对辐射防护进行有益改进的观点

当前的辐射防护框架为保护工作人员,保护公众和保护环境提供了足够的基础,然而国际的和国家的辐射防护组织目前正致力于改进、澄清和强化辐射防护的原则,这也正是我们在辐射安全护领域不断改进,追求卓越的文化。因此,核能工业界感谢有机会对这一努力提出自己的观点。核能工业界从三个方面提出自己的观点：作为运营者,承担着保护人的健康与安全和保护环境的主要职责;作为许可证持有者,负责遵守政府的法规;作为能源生产者,负责为消费者提供安全、可靠和经济的电力生产。对于如何改进辐射防护原则,目标是帮助促成在科学上有明确表述依据的成果;这些成果在当前和未来的被审管的广泛活动中的应用是灵活的;它的实施和维持是可行的,有成本效益的。     

Circular array of outward sloping monopoles for vehicular diversityantennas

A circular array of outward-sloping monopoles is analyzed as a diversity antenna for vehicle rooftop mounting. The monopoles are assumed to approximate minimum scattering antennas, have sinusoidal current distributions, and reside on an infinite, perfectly conducting ground plane. The envelopes of the received signals are considered Rayleigh distributed. The advantage of the array configuration is that the feedpoint spacing can be made almost arbitrarily small, even for a large number of branches. A three-element array with element lengths of 0.6 wavelengths and feedpoint spacing 0.1 wavelengths operating at 463 MHz was field-tested and the results are in good agreement with the analysis     

Acoustic beam position monitor for microanalysis of particles in the 10 nm range in a TEM-SCAN system

This paper describes the principle and use of a simple equipment which makes it possible to keep the electron beam in the centre of a small particle analysed by X-ray microanalysis in a STEM system. A deviation from the correct beam position introduced by drift or other deficiencies is monitored by an audible change in a sound frequency and corrected for by a convenient manual operation.     

User profiling and virtual agents: a case study on e-commerce services

The main contribution of this work is the design of an application framework based on both conversational agents and user profiling technologies for the development of e-commerce services. User profiles are exploited by conversational agents to help customers in retrieving potentially interesting products from a catalogue. Three techniques were used for collecting data for a usability test: eye-movement tracking, questionnaire, and recording the user-system dialogue. The main outcomes of the experimental sessions are: (1) the dialogue capabilities of the agent facilitate the interaction between the user and the e-commerce site; and, (2) user profiles improve the retrieval capabilities of the agent. Finally, some limitations of the user profiling techniques adopted in the framework are discussed and a more sophisticated content-based profiling technique is proposed.     

Estrogenic personal care products in a greywater reuse system.

The occurrence and fate of parabens in a greywater system was assessed. The potential for removal of residual paraben concentrations in effluent greywater with chlorine dioxide was also investigated. The influent to the greywater plant was characterised by considerable variation, with concentrations from below the detection limit to 40 microg/L and the five commonly used parabens in consumer products were frequently detected. After the biological treatment only two paraben were detected with concentration from 65-120 ng/L. Chlorine dioxide treatment of the biologically treated effluent with dosages down to 0.75 mg/L resulted in more than 97% reduction of all parabens. Formation of the by-product chloroform was insignificant from the chlorine dioxide treatment.     

Resolving crises through automated bilateral negotiations

We describe the development of an automated agent that can negotiate efficiently with people in crises. The environment is characterized by two negotiators, time constraints, deadlines, full information, and the possibility of opting out. The agent can play either role, with communications via a pre-defined language. The model used in constructing the agent is based on a formal analysis of the crises scenario using game-theoretic methods and heuristics for bargaining. The agent receives messages sent by its opponent, analyzes them and responds. It also initiates discussion on one or more parameters of an agreement. Experimental results of simulations of a fishing dispute between Canada and Spain indicate that the agent played at least as well as, and in the case of Spain, significantly better than a human player.