Stator iron loss of tubular permanent-magnet machines

While methods of determining the iron loss in rotating permanent-magnet (PM) machines have been investigated extensively, the study of iron loss in linear machines is relatively poorly documented. This paper describes a simple analytical method to predict flux density waveforms in discrete regions of the laminated stator of a tubular PM machine, and employs an established iron loss model to determine the iron loss components, on both no load and on load. Analytical predictions are compared with the iron loss deduced from finite-element analyses for two tubular PM machine designs, and it is shown that if a machine has a relatively high electrical loading, the on-load iron loss can be significantly higher than the no-load value

Figures of Merit for Testing Standard Models: Application to Dark Energy Experiments in Cosmology

Given a standard model to test, an experiment can be designed to: (i) measure the standard model parameters; (ii) extend the standard model; or (iii) look for evidence of deviations from the standard model. To measure (or extend) the standard model, the Fisher matrix is widely used in cosmology to predict expected parameter errors for future surveys under Gaussian assumptions. In this article, we present a frame- work that can be used to design experiments such that it maximises the chance of finding a deviation from the standard model. Using a simple illustrative example, discussed in the appendix, we show that the optimal experimental configuration can depend dramatically on the optimisation approach chosen. We also show some simple cosmology calculations, where we study Baryonic Acoustic Oscillation and Supernove surveys. In doing so, we also show how external data, such as the positions of the CMB peaks measured by WMAP, and theory priors can be included in the analysis. In the cosmological cases that we have studied (DETF Stage III), we find that the three optimisation approaches yield similar results, which is reassuring and indicates that the choice of optimal experiment is fairly robust at this level. However, this may not be the case as we move to more ambitious future surveys.Comment: Submitted to MNRAS. 12 pages, 9 figure

Understanding the nucleation mechanisms of Carbon Nanotubes in catalytic Chemical Vapor Deposition

The nucleation of carbon caps on small nickel clusters is studied using a tight binding model coupled to grand canonical Monte Carlo simulations. It takes place in a well defined carbon chemical potential range, when a critical concentration of surface carbon atoms is reached. The solubility of carbon in the outermost Ni layers, that depends on the initial, crystalline or disordered, state of the catalyst and on the thermodynamic conditions, is therefore a key quantity to control the nucleation

Discourse and Discography: The Pushback of Female Writers, Characters, and Pop Stars

In my senior thesis, I will be analyzing and comparing early modern literature and contemporary popular music in order to follow the development of women’s ability to gain power. Throughout history, there has been an ongoing struggle for women’s equity in education, publishing, and socially acceptable actions. Though the connection between literature and pop music is unordinary, there are major connections that show a consistent female struggle - the inability to voice one’s true feelings due to the reaction of an educated man or an unchanging society. Overall, the response of female characters, authors, and artists is to show their power by responding to unequal claims concerning their abilities and their right to say how they truly feel; this is a crucial aspect of my research that shows the connection between early modern literature and pop music. My thesis will focus on literary works such as Chaucer’s The Canterbury Tales, Phillips’s “Thoughts on Marriage,” and Swift’s “The Lady’s Dressing Room.” Because opportunities for women to publish their writing were limited due to social constructs of early literary periods, discussions of women’s abilities or opinions often came from the mind of a man. This became problematic as skewed opinions were shared based on bias and antifeminist ideals. Once women were being published more often, the outcry of truly feminine-based thoughts concerning power were known. In addition to early modern literature, I will be focusing on 2000s/2010s popular music artists including Ariana Grande and Taylor Swift. While analyzing lyrics that show direct relation to real-life experiences where these female artists respond to a situation by taking power over it, I will also be exploring problematic actions seen within pop culture that show the objectification and power-hungry wolves that have tried to belittle these women. Connecting these ongoing experiences of women gaining power over a society or man that has tried to hold them back over several centuries brings a new kind of light onto an ever-present struggle

Discourse and Discography: The Pushback of Female Writers, Characters, and Pop Stars

In my senior thesis, I will be analyzing and comparing early modern literature and “pop” music in order to follow the development of women’s ability to gain power. Throughout history, there has been an ongoing struggle for women’s equity in education, publishing, and socially acceptable actions. While it may seem that comparing literature from the 17th Century to current pop lyrics, there are major connections that show a consistent female struggle - the inability to voice one’s true feelings due to the reaction of an educated man or an unchanging society. My thesis will focus on literary works such as Chaucer’s The Canterbury Tales, Philips’s “Thoughts on Marriage,” and Swift’s “The Lady’s Dressing Room.” I will also be focusing on 2000s/2010s popular music artists including Ariana Grande and Taylor Swift. Connecting these ongoing experiences of women gaining power over the last few centuries will bring a new kind of light onto an ever-present struggle

iCosmo: an Interactive Cosmology Package

Aims: The interactive software package iCosmo, designed to perform cosmological calculations is described. Methods: iCosmo is a software package to perform interactive cosmological calculations for the low redshift universe. Computing distance measures, the matter power spectrum, and the growth factor is supported for any values of the cosmological parameters. It also computes derived observed quantities for several cosmological probes such as cosmic shear, baryon acoustic oscillations and type Ia supernovae. The associated errors for these observables can be derived for customised surveys, or for pre-set values corresponding to current or planned instruments. The code also allows for the calculation of cosmological forecasts with Fisher matrices which can be manipulated to combine different surveys and cosmological probes. The code is written in the IDL language and thus benefits from the convenient interactive features and scientific library available in this language. iCosmo can also be used as an engine to perform cosmological calculations in batch mode, and forms a convenient adaptive platform for the development of further cosmological modules. With its extensive documentation, it may also serve as a useful resource for teaching and for newcomers in the field of cosmology. Results: The iCosmo package is described with various examples and command sequences. The code is freely available with documentation at http://www.icosmo.org, along with an interactive web interface and is part of the Initiative for Cosmology, a common archive for cosmological resources.Comment: 6 pages including 2 tables and 4 figures. Accepted and published in Astronomy and Astrophysics. Public code and further resources available at http://www.icosmo.or

Importance of carbon solubility and wetting properties of nickel nanoparticles for single wall nanotube growth

Optimized growth of Single Wall Carbon Nanotubes requires a full knowledge of the actual state of the catalyst nanoparticle and its interface with the tube. Using Tight Binding based atomistic computer simulations, we calculate carbon adsorption isotherms on nanoparticles of nickel, a typical catalyst, and show that carbon solubility increases for smaller nanoparticles that are either molten or surface molten under experimental conditions. Increasing carbon content favors the dewetting of Ni nanoparticles with respect to sp2 carbon walls, a necessary property to limit catalyst encapsulation and deactivation. Grand Canonical Monte Carlo simulations of the growth of tube embryos show that wetting properties of the nanoparticles, controlled by carbon solubility, are of fundamental importance to enable the growth, shedding a new light on the growth mechanisms

Fisher matrix decomposition for dark energy prediction

Within the context of constraining an expansion of the dark energy equation of state w(z), we show that the eigendecomposition of Fisher matrices is sensitive to both the maximum order of the expansion and the basis set choice. We investigate the Fisher matrix formalism in the case that a particular function is expanded in some basis set. As an example we show results for an all-sky weak lensing tomographic experiment. We show that the set of eigenfunctions is not unique and that the best constrained functions are only reproduced accurately at very higher order N≳ 100, a top-hat basis set requires an even higher order. We show that the common approach used for finding the marginalized eigenfunction errors is sensitive to the choice of non-w(z) parameters and priors. The eigendecomposition of Fisher matrices is a potentially useful tool that can be used to determine the predicted accuracy with which an experiment could constrain w(z). It also allows for the reconstruction of the redshift sensitivity of the experiment to changes in w(z). However, the technique is sensitive to both the order and the basis set choice. Publicly available code is available as part of icosmo at http://www.icosmo.or

Figures of merit for testing standard models: application to dark energy experiments in cosmology

Given a standard model to test, an experiment can be designed to (i) measure the standard model parameters, (ii) extend the standard model or (iii) look for evidence of deviations from the standard model. To measure (or extend) the standard model, the Fisher matrix is widely used in cosmology to predict expected parameter errors for future surveys under Gaussian assumptions. In this paper, we present a framework that can be used to design experiments that will maximize the chance of finding a deviation from the standard model. Using a simple illustrative example, discussed in Appendix A, we show that the optimal experimental configuration can depend dramatically on the optimization approach chosen. We also show some simple cosmology calculations, where we study baryonic acoustic oscillation and supernovae surveys. In doing so, we also show how external data, such as the positions of the cosmic microwave background peak measured by Wilkinson Microwave Anisotropy Probe, and theory priors can be included in the analysis. In the cosmological cases that we have studied (Dark Energy Task Force Stage III), we find that the three optimization approaches yield similar results, which is reassuring and indicates that the choice of optimal experiment is fairly robust at this level. However, this may not be the case as we move to more ambitious future survey