Controls and Interfaces

Reliable powering of accelerator magnets requires reliable power converters and controls, able to meet the powering specifications in the long term. In this paper, some of the issues that will challenge a power converter controls engineer are discussed.Comment: 16 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201

High temperature refractory member with radiation emissive overcoat

A radiation type heat dissipator for use in a plasma engine is formed of a refractory metal layer upon which there is deposited a radiation emissive coating made of a high emissivity material such as zirconium diboride. The radiation emissive coating has a surface emissivity coefficient substantially greater than the emissivity coefficient of the refractory metal and thereby enhances the optical radiating efficiency of the heat dissipator

Finding Their Why : Examining the Development of Sense of Purpose During the University Years and Its Role in Student Well-Being

Nearly 20 million students were expected to be enrolled for college or university studies during the 2020-2021 academic year. These institutions often advertise to prospective students that, in addition to advancing their education, they will discover their purpose. Given previous work and current interest in sense of purpose, additional attention on sense of purpose in the university setting is worthwhile. In addition, as many university stakeholders are concerned about an ongoing mental health crisis, a further examination into a developmental construct (i.e. sense of purpose) thought to provide a “sheltering fortress in a world of constant threat” seems especially relevant. In the present two-study dissertation, Study 1, a quantitative study, was designed to examine sense of purpose as a potential buffer between university-related stress and psychological distress. Results from this study suggest sense of purpose moderates the relationship between stress and burnout for sophomores but not other years in school. Study 2, a qualitative study, was designed to provide an in-depth exploration into the perceptions of graduating seniors on the development of their sense of purpose during the university experience. Results from this study highlight that participants’ perceptions that the university played a key role in exposing them to a broader world, helping further establish identity and values, while providing structure and support. Independently, the studies possess the potential to offer unique contributions to current understanding of sense of purpose and inform meaningful research directions in the future. Considered together, the results have the potential to offer important practical considerations for college and university staff and administrators involved with student well-being and retention

Stillbirth: A Phenomenological Exploration of the Clinical Encounter for Couples

With approximately 65 stillbirths occurring each day in the United States, a significant number of parents are left to navigate a difficult grieving process. An event like stillbirth presents many individual and relational challenges. For this study, researchers focused on the hospital experience for couples following notification of stillbirth. Interviews were held with 8 couples that had experienced stillbirth within the past 10 years. Researchers wanted to know what similarities and differences existed in how mothers and fathers described the clinical encounter. The data for this study were collected through interviews. Couples were encouraged to share as much or as little as they’d like about the hospital experience. Couples were also asked to describe how they experienced the clinical encounter as individuals and as a couple. Participants in this study were also given the opportunity to provide feedback on what doctors and other hospital staff could do to assist individuals and couples during this difficult time. Participants discussed how hospital staff helped to shape the experience. This was done both in their interactions with staff and the accommodations that were made. Some parents described hospital staff as “gems” or their “angels” while others reported the pain of hospital staff invalidating their experience. While similarities existed in how parents experienced the clinical encounter, each participant’s experience was unique. Studies should continue to be conducted in an effort to further develop evidence-based practices in hospitals meant to help parents navigate this difficult experience

The NASA Electric Propulsion Program

The NASA OAST Propulsion, Power, and Energy Division supports an electric propulsion program aimed at providing benefits to a broad class of missions. Concepts which have the potential to enable or significantly benefit space exploration and exploitation are identified and advanced toward application in the near and far term. This paper summarizes recent program progress in mission/system analysis; in electrothermal, electrostatic, and electromagnetic propulsion technologies; and in propulsion/spacecraft integration

Corrections to Tribimaximal Mixing from Nondegenerate Phases

We propose a seesaw scenario that possible corrections to the tribimaximal pattern of lepton mixing are due to the small phase splitting of the right-handed neutrino mass matrix. we show that the small deviations can be expressed analytically in terms of two splitting parameters($\delta_1$ and $\delta_2$) in the leading order. The solar mixing angle $\theta_{12}$ favors a relatively smaller value compared to zero order value ($35.3^\circ$), and the Dirac type CP phase $\delta$ chooses a nearly maximal one. The two Majorana type CP phases $\rho$ and $\sigma$ turn out to be a nearly linear dependence. Also a normal hierarchy neutrino mass spectrum is favored due to the stability of perturbation calculations.Comment: 19 pages 6 figures, Accepted by Mod. Phy. Lett.

Thermal design improvements for 30kWe arcjet engine

Two thermal design improvements for 30 kWe arcjet engines are described. A ZrB2 high temperature coating was used to increase the surface emissivity of the nozzle radiating surface, enabling lower temperature operation, which should lead to longer nozzle life. The ZrB2-coated engine operated 120 C cooler than the uncoated baseline engine indicating a 30 percent increase in the surface emissivity. An engine design which has fewer active seals than previous designs and operates at lower overall component temperatures is described. The nozzle on the engine operated at 1950 C at 30 kWe while the baseline engine nozzle reached 2000 C at 23 kWe. The back of the engine was more than a factor of two cooler when compared to the baseline engine

Quark and Lepton Mass Patterns and the Absolute Neutrino Mass Scale

We investigate what could be learned about the absolute scale of neutrino masses from comparisons among the patterns within quark and lepton mass hierarchies. First, we observe that the existing information on neutrino masses fits quite well to the unexplained, but apparently present regularities in the quark and charged lepton sectors. Second, we discuss several possible mass patterns, pointing out that this quite generally leads towards hierarchical neutrino mass patterns especially disfavoring the vacuum solution.Comment: final version to be published in PRD, 5 pages, 2 figures, RevTe

Supersymmetric Hybrid Inflation with Non-Minimal Kähler potential

Minimal supersymmetric hybrid inflation based on a minimal Kahler potential predicts a spectral index n_s\gsim 0.98. On the other hand, WMAP three year data prefers a central value n_s \approx 0.95. We propose a class of supersymmetric hybrid inflation models based on the same minimal superpotential but with a non-minimal Kahler potential. Including radiative corrections using the one-loop effective potential, we show that the prediction for the spectral index is sensitive to the small non-minimal corrections, and can lead to a significantly red-tilted spectrum, in agreement with WMAP.Minimal supersymmetric hybrid inflation based on a minimal Kahler potential predicts a spectral index n_s\gsim 0.98. On the other hand, WMAP three year data prefers a central value n_s \approx 0.95. We propose a class of supersymmetric hybrid inflation models based on the same minimal superpotential but with a non-minimal Kahler potential. Including radiative corrections using the one-loop effective potential, we show that the prediction for the spectral index is sensitive to the small non-minimal corrections, and can lead to a significantly red-tilted spectrum, in agreement with WMAP.Minimal supersymmetric hybrid inflation based on a minimal Kähler potential predicts a spectral index ns≳0.98 . On the other hand, WMAP three year data prefers a central value ns≈0.95 . We propose a class of supersymmetric hybrid inflation models based on the same minimal superpotential but with a non-minimal Kähler potential. Including radiative corrections using the one-loop effective potential, we show that the prediction for the spectral index is sensitive to the small non-minimal corrections, and can lead to a significantly red-tilted spectrum, in agreement with WMAP