Nonlinear Dynamics of Particles Excited by an Electric Curtain

The use of the electric curtain (EC) has been proposed for manipulation and control of particles in various applications. The EC studied in this paper is called the 2-phase EC, which consists of a series of long parallel electrodes embedded in a thin dielectric surface. The EC is driven by an oscillating electric potential of a sinusoidal form where the phase difference of the electric potential between neighboring electrodes is 180 degrees. We investigate the one- and two-dimensional nonlinear dynamics of a particle in an EC field. The form of the dimensionless equations of motion is codimension two, where the dimensionless control parameters are the interaction amplitude ($A$) and damping coefficient ($\beta$). Our focus on the one-dimensional EC is primarily on a case of fixed $\beta$ and relatively small $A$, which is characteristic of typical experimental conditions. We study the nonlinear behaviors of the one-dimensional EC through the analysis of bifurcations of fixed points. We analyze these bifurcations by using Floquet theory to determine the stability of the limit cycles associated with the fixed points in the Poincar\'e sections. Some of the bifurcations lead to chaotic trajectories where we then determine the strength of chaos in phase space by calculating the largest Lyapunov exponent. In the study of the two-dimensional EC we independently look at bifurcation diagrams of variations in $A$ with fixed $\beta$ and variations in $\beta$ with fixed $A$. Under certain values of $\beta$ and $A$, we find that no stable trajectories above the surface exists; such chaotic trajectories are described by a chaotic attractor, for which the the largest Lyapunov exponent is found. We show the well-known stable oscillations between two electrodes come into existence for variations in $A$ and the transitions between several distinct regimes of stable motion for variations in $\beta$

Combating Militant Islamism with Psychological Operations: Influencing Adversary Behavior

This research serves as an evaluation of the United States’ Psychological Operations (PSYOP) strategy in combating militant Islamist groups. Department of Defense doctrinal publications are the authority in this thesis for defining PSYOP. The research considers past U.S. employment of PSYOP to demonstrate its plausible effectiveness in achieving national security objectives. Analysis supports the idea of PSYOP being an appropriate means to combat militant Islamism. A thorough look into the authoritative texts that militant Islamist groups use to support their ideology leads to the conclusion that the U.S.’s current employment of PSYOP is misdirected and subsequently ineffective. The researcher concludes that an alternative approach involving the use of PSYOP to discredit the militants’ stated ideological source, namely the Quran and Hadith, rather than attempting to simply discredit their interpretation of the texts, would be more effective in influencing adversarial thoughts and behavior to support U.S. national security objectives

How Volcanic Explosions Interface with Infrastructure: A Brief Analysis of Volcano Infrasound\u27s Influence on Fuego Observatory Near Fuego Volcano, Guatemala

In 2022, roughly 9 kilometers from the summit of the volcano at Fuego Observatory in Guatemala, our team deployed two arrays of low frequency microphones (infrasound sensors) to capture the effects of Fuego Volcano’s semi-active period explosions on the observatory building. We hypothesized a discernible differential pressure signal and frequency spectra content between sensors placed inside and outside of the observatory. The peak force exerted on a building by volcano infrasound, depending upon the strength of the explosion and distance from it, may be enough to damage windows or even entire buildings if they are poorly built/kept. This presentation aims to contextualize volcanic explosion emitted infrasound as a potential geophysical hazard capable of harming infrastructure

Are multiphase competition & order-by-disorder the keys to understanding Yb2Ti2O7?

If magnetic frustration is most commonly known for undermining long-range order, as famously illustrated by spin liquids, the ability of matter to develop new collective mechanisms in order to fight frustration is no less fascinating, providing an avenue for the exploration and discovery of unconventional properties of matter. Here we study an ideal minimal model of such mechanisms which, incidentally, pertains to the perplexing quantum spin ice candidate Yb2Ti2O7. Specifically, we explain how thermal and quantum fluctuations, optimized by order-by-disorder selection, conspire to expand the stability region of an accidentally degenerate continuous symmetry U(1) manifold against the classical splayed ferromagnetic ground state that is displayed by the sister compound Yb2Sn2O7. The resulting competition gives rise to multiple phase transitions, in striking similitude with recent experiments on Yb2Ti2O7 [Lhotel et al., Phys. Rev. B 89 224419 (2014)]. Considering the effective Hamiltonian determined for Yb2Ti2O7, we provide, by combining a gamut of numerical techniques, compelling evidence that such multiphase competition is the long-sought missing key to understanding the intrinsic properties of this material. As a corollary, our work offers a pertinent illustration of the influence of chemical pressure in rare-earth pyrochlores.Comment: 9 page

Freedom of Conscience: A Communal-based Approach

Despite the plethora of freedom of religion literature (under section 2(a) of the Canadian Charter of Rights and Freedoms), the corresponding literature on the freedom of conscience is minimal. To further the discussion on the freedom of conscience, I rely heavily on the philosophical literature to make an important distinction; the difference between individual- based and communal-based conceptions of conscience. Whereas the former is plagued with subjectivity, making it difficult to conceptualize a working framework for the Charter right, the latter offers a promising foothold to rise above subjectivity and find a firm footing based on communal relations. In emphasizing the importance of the dialogical nature of human beings and the relational necessity undergirding moral judgements, I argue that the concept of conscience should be understood and practiced in community, rather than individually