Study and design of a cryogenic propellant acquisition system

The development of an acquisition system for supplying subcooled liquid hydrogen and liquid oxygen under in-orbit conditions is discussed. The system will be applied to the integrated cryogenic feed requirements for space systems such as a space shuttle cryogenic auxiliary propulsion system (APS) and main propulsion for an advanced spacecraft propulsion module (ASPM). Concepts that use the favorable surface tension characteristics of fine mesh screens are emphasized. The specific objectives of the program are: (1) to evolve conceptual designs for candidate acquisition systems, (2) to formulate the analytical models needed to analyze the systems, and (3) to generate parametric data on overall candidate system performance, characteristics, and operational features in sufficient depth to establish critical design problems and criteria to support a sound system design and evaluation

Study and design of cryogenic propellant acquisition systems. Volume 2: Supporting experimental program

Areas of cryogenic fuel systems were identified where critical experimental information was needed either to define a design criteria or to establish the feasibility of a design concept or a critical aspect of a particular design. Such data requirements fell into three broad categories: (1) basic surface tension screen characteristics; (2) screen acquisition device fabrication problems; and (3) screen surface tension device operational failure modes. To explore these problems and to establish design criteria where possible, extensive laboratory or bench test scale experiments were conducted. In general, these proved to be quite successful and, in many instances, the test results were directly used in the system design analyses and development. In some cases, particularly those relating to operational-type problems, areas requiring future research were identified, especially screen heat transfer and vibrational effects

Studies of radioactive nuclei and their role in the cosmos

Producing and accelerating radioactive nuclei in the laboratory provides a unique tool for the study of nuclear reactions involving these isotopes in the energy regime of interest for astrophysics. We briefly review some recent developments with accelerated radioactive ion beams and their impact for astrophysics. © Copyright owned by the author(s)

What do (and don\u27t) we understand about explosive nucleosynthesis?

Isotopic abundances reflect both nuclear structure and environmental history. Observations are providing new evidence that is helping us to understand astrophysical phenomena, the chemical history of the Galaxy, and the origins of the diverse isotopic abundances found on earth. What we infer from observations, however, depends upon a robust understanding of the underlying nuclear physics. The difficulties involved in producing and studying short-lived isotopes are particularly problematic for understanding stellar explosions. While new facilities and experimental techniques have recently spurred significant progress in our understanding of the light, proton-rich nuclei that are important for understanding novae, studies of heavier exotic nuclei that are crucial for understanding more energetic explosions and the origins of the heavy elements are still quite challenging. We briefly survey recent progress in experimental nuclear physics that is important for understanding explosive nucleosynthesis and outline some of the major outstanding questions and the prospects for future advances

Students’ Experiences with Community in an Open Access Course

Online open access courses have become regular offerings of many universities. Building community and connectedness is an important part of branding and success of such offerings. Our goal was to investigate students’ experiences with community in an open access course. Therefore, in this study, we explored the sense of community of 342 participants in an open access chemistry course. We found that participants did not rate a sense of community as important to them, and did not report feeling very connected to the online course. We will discuss opportunities for building community features in such courses in the future

Relating Peak Optical Luminosity and Orbital Period of Stellar-Mass Black Holes in X-ray Binaries

We compare the peak optical luminosity with the orbital period for a sample of 22 stellar-mass black hole candidates with good measurements of both quantities. We find that the peak absolute magnitude for the outbursts follows a linear relation with $M_{V,peak}=3.48 (\pm 0.85)-3.89 (\pm 0.91) {\rm log}P_{orb}$, which corresponds to a $L_V \propto P_{orb}^{1.56\pm 0.36}$ power law relation. Excluding V4641 Sgr which is a strong outlier and not likely to have outbursts produced by the standard disc instability model, in addition to BW Cir and V821 Ara -- both of which have highly uncertain distances; the new correlation for the 19 sources is found to be $M_{V,peak}= 3.01\;(\pm 0.93)-3.21\;(\pm 1.04){\rm log}P_{orb}$, which corresponds to $L_V \propto P_{orb}^{1.28 \pm 0.42}$. This is an analogous relationship to the "Warner relation" between orbital period and peak luminosity found for cataclysmic variables. We discuss the implications of these results for finding black hole X-ray binaries in other galaxies and in our own Galaxy with the Large Synoptic Survey Telescope and other future large time domain surveys.Comment: 6 pages, 2 figures, submitted to MNRA

Study and design of cryogenic propellant acquisition systems. Volume 1: Design studies

An in-depth study and selection of practical propellant surface tension acquisition system designs for two specific future cryogenic space vehicles, an advanced cryogenic space shuttle auxiliary propulsion system and an advanced space propulsion module is reported. A supporting laboratory scale experimental program was also conducted to provide design information critical to concept finalization and selection. Designs using localized pressure isolated surface tension screen devices were selected for each application and preliminary designs were generated. Based on these designs, large scale acquisition prototype hardware was designed and fabricated to be compatible with available NASA-MSFC feed system hardware

Making the Connection: Using Mobile Devices and PollEverywhere for Experiential Learning for Adult Students

Technology integration has significantly influenced the way students access and retain knowledge gained in the classroom (Ahmed, 2016). This is particularly relevant in classrooms for adult learners who engage in continuing education. This paper used a descriptive case study (Yin, 2014) to share how an instructor utilized mobile learning with a web-based polling tool, PollEverywhere, to gamify experiential learning for adult students in various roles within a southeastern state’s court administration—prosecutors, defense lawyers, magistrates, and jail administrators—and improve students’ engagement in the course and connection to course material

Teaching Online, Challenges and Motivations: A Research Synthesis

Millions of students are enrolled in online classes, and while some faculty members are still concerned about the medium, other faculty members are excited about the possibilities of online learning. In order to gauge what hinders or motivates faculty members’ online teaching, I conducted a research synthesis to examine the literature from 2002 to the present that addressed the motivations and concerns of instructors around the world. Although the time from 2002 until the present marks a little over 10 years of work related to online teaching, faculty members’ concerns and motivations have not changed much during that time

Unbound states of 32Cl and the 31S(p,\gamma)32Cl reaction rate

The 31S(p,\gamma)32Cl reaction is expected to provide the dominant break-out path from the SiP cycle in novae and is important for understanding enrichments of sulfur observed in some nova ejecta. We studied the 32S(3He,t)32Cl charge-exchange reaction to determine properties of proton-unbound levels in 32Cl that have previously contributed significant uncertainties to the 31S(p,\gamma)32Cl reaction rate. Measured triton magnetic rigidities were used to determine excitation energies in 32Cl. Proton-branching ratios were obtained by detecting decay protons from unbound 32Cl states in coincidence with tritons. An improved 31S(p,\gamma)32Cl reaction rate was calculated including robust statistical and systematic uncertainties