993 resultados para right-angle prism


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Thermosetting polymer blends of poly(ethylene oxide) (PEO) and bisphenol-A-type epoxy resin (ER) were prepared using 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) as curing agent. The miscibility and crystallization behavior of MCDEA-cured ER/PEO blends were investigated by differential scanning calorimetry (DSC). The existence of a single composition-dependent glass transition temperature (Tg) indicates that PEO is completely miscible with MCDEA-cured ER in the melt and in the amorphous state over the entire composition range. Fourier-transform infrared (FTIR) investigations indicated hydrogen-bonding interaction between the hydroxyl groups of MCDEA-cured ER and the ether oxygens of PEO in the blends, which is an important driving force for the miscibility of the blends. The average strength of the hydrogen bond in the cured ER/PEO blends is higher than in the pure MCDEA-cured ER. Crystallization kinetics of PEO from the melt is strongly influenced by the blend composition and the crystallization temperature. At high conversion, the time dependence of the relative degree of crystallinity deviated from the Avrami equation. The addition of a non-crystallizable ER component into PEO causes a depression of both the overall crystallization rate and the melting temperature. The surface free energy of folding σe displays a minimum with variation of composition. The spherulitic morphology of PEO in the ER/PEO blends exhibits typical characteristics of miscible crystalline/amorphous blends, and the PEO spherulites in the blends are always completely volume-filling. Real-time small-angle X-ray scattering (SAXS) experiments reveal that the long period L increases drastically with increasing ER content at the same temperatures. The amorphous cured ER component segregates interlamellarly during the crystallization process of PEO because of the low chain mobility of the cured ER. A model describing the semicrystalline morphology of MCDEA-cured ER/PEO blends is proposed based on the SAXS results. The semicrystalline morphology is a stack of crystalline lamellae; the amorphous fraction of PEO, the branched ER chains and imperfect ER network are located between PEO lamellae.

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We examine efficient computer implementation of one method of deterministic global optimisation, the cutting angle method. In this method the objective function is approximated from values below the function with a piecewise linear auxiliary function. The global minimum of the objective function is approximated from the sequence of minima of this auxiliary function. Computing the minima of the auxiliary function is a combinatorial problem, and we show that it can be effectively parallelised. We discuss the improvements made to the serial implementation of the cutting angle method, and ways of distributing computations across multiple processors on parallel and cluster computers.

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Many problems in chemistry depend on the ability to identify the global minimum or maximum of a function. Examples include applications in chemometrics, optimization of reaction or operating conditions, and non-linear least-squares analysis. This paper presents the results of the application of a new method of deterministic global optimization, called the cutting angle method (CAM), as applied to the prediction of molecular geometries. CAM is shown to be competitive with other global optimization techniques for several benchmark molecular conformation problem. CAM is a general method that can also be applied to other computational problems involving global minima, global maxima or finding the roots of nonlinear equations.

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An angle measuring device using a high performance and very compact accelerometer provides a new and exciting method for producing highly compact and accurate angle measuring devices. Accelerometers are micro-machined and are able to measure acceleration to a very high accuracy. By using gravity as a reference these compact devices can also be used for measuring angles of rotation. The inherent problem with these devices is that their response characteristic changes with temperature which is detrimental to measurement accuracy. This paper describes an effective method to overcome this problem using a temperature sensor and intelligent software to compensate for this drift characteristic. In order to demonstrate the effectiveness of this work, experiments have been developed and conducted with the results and analysis provided at the end
of this paper for discussion.

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Cultural diversity in tertiary classrooms is integral to the current university scene. Teachers must incorporate different methods of delivery and
assessment to cater for an increasingly international student population. This paper explores the notion of plagiarism from two perspectives: the law
and English as a Second Language (ESL) writing theory.

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In this paper we discuss the ghost node problem found when triangulation of 2 or more nodes is required. We present and discuss a simple algorithm, termed ABLE (Angle Based Location Estimation), that will position randomly placed emitters in a wireless sensor network using a mobile antenna array. The individual nodes in the network are relieved of the localization task by the mobile antenna system and require no modifications to account for location determination. Furthermore, no beacon nodes (i.e. nodes that know their own position) are required. We provide analysis that indicates a reasonably small number of measurements are required to guarantee the successful
localization of the emitting nodes and demonstrate our results through simulation.

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The use of willingness to pay to value the benefits of health care is increasing. Much of this work assumes that health preferences are well formed or complete and readily revealed if the right question is asked in the right way. We examined this assumption, seeking evidence in a mixed-methods study that explored the meaning and implications of vague responses to a payment-scale based willingness to pay exercise.

One-half of the sample said that their vagueness meant that their maximum willingness to pay was actually greater than the amount that they had previously said it was. Thirty percent agreed that they would probably pay £10 more than a sum that they had previously said they would most definitely not pay, if they found this to be the cost of the vaccine. Interview data supported the view that the payment scale had failed to elicit the maximum willingness to pay and that some participants used the information on cost to help clarify their values, in contrast to the theory underpinning willingness to pay. The results suggest a need to consider values-clarification in health economic evaluations. Copyright © 2002 John Wiley & Sons, Ltd.

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This paper introduces the concept of terminal attitude guidance as an alternative to precision guidance and uses fuzzy control ideas in designing a control strategy for a pursuer in countering a manoeuvreing target. The fuzzy controller uses only angle measurements in the control strategy and produces satisfactory results in comparison to the LQR or H∞ type guidance controllers, although they were addressed in a precision guidance context. Both 2D and 3D cases have been considered.

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This article explores the tacit understanding of teachers in the field of gifted educational practices after their participation in gifted education professional development. The data for this article are drawn from a single-case qualitative study where semi-structured interviews were held with teachers, administrators and support staff in a metropolitan Victorian primary school. The findings lead to two main arguments: first, that some teachers preserved their deeply entrenched beliefs and assumptions about the gifted, the talented and intelligence[s]; and second, that teachers, without critical examination, eagerly adopted and adapted Gardner's Multiple Intelligences theory, overlaid with Bloom's Revised Taxonomy of Thinking as a means for addressing individual differences in the classroom. The article argues that teachers welcomed the Gardner/Bloom matrix for its 'tick-the-box' simplicity, with little insight into the theoretical models. Whilst the matrix had an immediate value in the mixed ability classrooms, in the long term it did not support the learning needs of gifted students. [Author abstract]

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In this paper, we examine the geometric relations between various measured parameters and their corresponding errors in angle-measurement based emitter localization scenarios. We derive a geometric constraint formulating the relationship among the measurement errors in such a scenario. Using this constraint, we formulate the localization task as a constrained optimization problem that can be performed on the measurements in order to provide the optimal values such that the solution is consistent with the underlying geometry.

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The capability of an employee to violate the policy of an organization is a concern for an employer. Monitoring is a measure taken by an employer to discourage an employee from acting inappropriately. However, current monitoring techniques tend to raise privacy issues because they violate the privacy rights of employees. Applying a monitoring technique without violating the privacy of employees is the aim of this paper. We propose a design and a protocol which give an employer the opportunity to monitor employee email in order to detect company policy violations. This can be achieved without violating the privacy of honest employees, while at the same time revealing evidence about the illegal actions of dishonest employees.

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What does it comfort any of us to insist that an individual shall be a man, when for the purposes of ordinary life that individual can only be, and be recognised, as a woman? What pride can there be for a law which vetoes the attitudes dictated by ordinary humanity?[1]

Those suffering from gender dysphoria have been described in the following simple language:

People with gender dysphoria or gender identity disorder live with a conviction that their physical anatomy is incompatible with their true gender role. They have an overwhelming desire to live and function in the opposite biological sex.