62970 research outputs found
Sort by
The Performance Comparisons of Single Board Computer Clusters
No full textThe rapid growth of edge computing, educational high-performance computing (HPC) environments, and cost-effective prototyping has led to increasing
interest in Single Board Computers (SBCs) as cluster nodes. These devices offer
low power consumption and affordability, but their performance and scalability characteristics across differing architectures have not been adequately studied. This thesis presents a comprehensive performance evaluation of SBC clusters through both architectural comparison and scalability testing using industrystandard benchmarks.
Two experimental cluster systems were developed and benchmarked. The
first is a triarchitecture heterogeneous SBC cluster composed of 12 nodes: four
x86-based Radxa X2L devices, four ARM-based Raspberry Pi Compute Module
4 units, and four RISC-V-based Lichee Pi 4A boards. The second system is
a homogeneous 20-node x86 Radxa X4L cluster, used primarily for multi-node
scalability analysis.
Benchmarks included High-Performance Linpack (HPL) for peak floatingpoint performance, Fast Fourier Transform (FFTW) for signal processing workloads, High-Performance Conjugate Gradient (HPCG) for memory-bound performance, and LAMMPS for molecular dynamics simulations. The results were
collected across varying numbers of threads and nodes to assess execution time,
speedup, GFLOPs, and efficiency.
The findings highlight significant differences in performance characteristics among the x86, ARM, and RISC-V SBC architectures. Although x86 nodes
delivered the highest raw performance, ARM SBCs offered superior performance
per watt and consistent scalability. RISC-V systems showed potential, but lagged
in maturity and performance. On the 20-node Radxa X4L cluster, strong scalability was observed up to 12–16 nodes, beyond which efficiency declined due to
inter-node communication overhead.
This work serves as a reference for researchers and system designers interested in leveraging SBCs for HPC-like workloads. It also provides insights
into architectural trade-offs and cluster scalability in resource-constrained environments
Where Gravity Fades: Adapting CFD Models for Extra-terrestrial Greenhouses
Get PDFLouise Fleischer, Université Clermont Auvergne, FranceLucie Poulet, Université Clermont Auvergne, FranceClaude-Gilles Dussap, Université Clermont Auvergne, FranceJean-Pierre Fontaine, Université Clermont Auvergne, FranceAlexis Paillet, Centre National d’Etudes Spatiales, FranceICES204: Bioregenerative Life SupportThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.This paper investigates the adaptation of computational
fluid dynamics (CFD) models initially developed for
terrestrial greenhouses, for application in
extraterrestrial plant growth environments such as in
orbit, on the Moon, or on Mars. Current CFD models in
terrestrial greenhouses simulate complex microclimates by
investigating airflow, temperature, humidity, and plant
canopy interactions. However, extraterrestrial environments
present unique challenges, including reduced gravity,
artificial lighting, and controlled ventilation, requiring
modification of several fundamental model parameters.
Drawing from the works of Fatnassi et al. and Poulet et
al., this study outlines necessary adjustments to key
equations governing free convection, stomatal and leaf
boundary layer conductance, and gas exchange processes
under non-Earth gravitational forces. This work aims to
establish the foundation of CFD models that are adapted to
controlled life-support systems for space missions,
facilitating realistic long-term simulations of plant
growth under extraterrestrial conditions
A Proposal of Fecal Transport Method for Space Toilet in Human Space Exploration: Experiments on Transport of Simulated Feces Using a Peristaltic Transfer Device to Save Water
Get PDFMiku Tsubouchi, Chuo University, JapanMasaki Kawano, Chuo University, JapanChiaki Yamazaki, Japan Aerospace Exploration Agency (JAXA), JapanFumio Ito, Chuo University, JapanTaro Nakamura, Chuo University, JapanICES304: Physico-Chemical Life Support- Waste Management
Systems- Technology and Process DevelopmentThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.This paper proposes a low-air-pressure-driven space toilet
system capable of transporting feces with minimal water
usage. In manned space missions, efficient resource
management is critical, as resupplying water and air is
costly. While urine recycling has been implemented at the
International Space Station (ISS), an effective system for
feces transportation and processing remains undeveloped.
Since feces contain a significant amount of water and
organic matter, their reuse could enhance the performance
of the Environmental Control and Life Support System
(ECLSS) and reduce resupply costs. However, conventional
Earth-based toilet systems, which rely on gravity and large
amounts of water, are not feasible in microgravity
environments. To address this issue, we developed a
transportation system inspired by the peristaltic movement
of biological intestines. The system consists of a series
of identical transfer units, each capable of replicating
peristaltic motion using low-pressure air. Simulated feces
with properties similar to human feces were successfully
transported using this system. Additionally, a small amount
of water was used to assist in transport and cleaning.
Given the high toilet usage frequency in space, further
minimizing water consumption is essential. Therefore, in
this study, experiments were conducted in which simulated
feces were transported consecutively, followed by an
optimized cleaning process utilizing a minimal amount of
water. The system’s transport performance and applicability
as a space toilet were evaluated based on the experimental
results. The findings demonstrate the feasibility of this
approach, contributing to the development of a sustainable
waste management system for future long-duration space
missions
Full-Scale Humidity Condensate Treatment Using a Hybrid Treatment System: Membrane Aerated Biological Pretreatment and Reverse Osmosis
Get PDFSunday Adu, Texas Tech University, United StatesBruno Lara, Texas Tech University, United StatesTristen Martin, Texas Tech University, United StatesMichael Callahan, NASA Johnson Space Center (JSC), United StatesWilliam Andrew Jackson, Texas Tech University, United StatesICES303: Physico-Chemical Life Support- Water Recovery &
Management Systems- Technology and Process DevelopmentThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.The development of efficient and sustainable water
recycling systems is essential for long-term human missions
and the establishment of space habitats on the Moon, Mars,
and beyond. Humidity Condensate (HC) is a low strength
wastewater that is currently recycled on ISS. The HC
contaminants are primarily low molecular weight organics
and ammonia. This has caused operational issues due to
microbial growth in the water processor assembly WPA
storage tank and failure of down-stream systems. In
addition, treatment of this wastewater primarily uses
adsorptive and exchange media, which must be continually
resupplied. This study demonstrates the integration of a
biological reactor for pre-treatment of HC coupled to a low
pressure (<60PSI) Reverse Osmosis (RO) system. The
bioreactor is a Membrane Aerated Bioreactor (MABR) which
supports micro-gravity compatible aeration and can serve as
the HC storage tank. The system was tested in two
configurations, with and without an RO recycling tank. The
MABR was challenged with a 4 crew-day load and the RO
system was run until a single membrane could not process
the 4-crew-day load in < 24 hours. Current results indicate
that the MABR removes > 80% DOC and that a single RO
membrane (260 grams) can process > 3000 L of wastewater.
RO effluent is near potable water reducing the need for
post treatment and thus reducing consumable consumption.
The results suggest that this hybrid system has the
potential to significantly enhance the self-sufficiency of
space habitats, supporting sustainable extra-terrestrial
human habitation as well as reducing current operational
problems on ISS
Boron Nitride Nanotube Reinforced Polyethylene Composite for Shielding Space Neutron Radiation for Human Space Flight
Get PDFPalak B. Patel, Massachusetts Institute of Technology (MIT), United StatesNicolas C. Joseph, Massachusetts Institute of Technology (MIT), South AfricaCheol Park, NASA Langley Research Center (LRC), United StatesValerie L. Wiesner, NASA Langley Research Center (LRC), United StatesBrian L. Wardle, Massachusetts Institute of Technology (MIT), United StatesICES503: Radiation Issues for Space FlightThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.NASA's Artemis program aims to establish a sustained human
presence on the Moon and, ultimately, on Mars, making
astronaut protection from radiation a priority. Materials
with spaceflight heritage, especially those high in
hydrogen content like polyethylene (PE), represent the
state-of-the-art in lightweight and effective radiation
shielding. This effectiveness comes from hydrogen’s
advantageous properties, including a high charge-to-mass
ratio, minimal secondary radiation production, efficient
energy absorption, and a high cross-section that increases
the likelihood of interactions to decelerate or halt
ionized particles. Boron nitride nanotubes (BNNTs) and
other boron-enriched materials offer superior thermal
neutron radiation shielding due to their high cross-section
and strong neutron absorption abilities. BNNTs also enhance
the mechanical properties of shielding materials due to
their high strength-to-weight ratio. The addition of BNNTs
to a wide range of spaceflight materials can enhance
mechanical and radiation shielding properties for
applications on the lunar and Martian surface. However,
integrating high volumes of nanotubes (more than 15 wt%) in
a matrix without defects, such as macro-voids and nanotube
agglomerations, presents significant manufacturing
challenges. Due to these challenges, state-of-the-art
research has led to marginal improvements in mechanical and
radiation shielding properties. To address this, a bulk
nanocomposite laminate fabricating technique is utilized to
integrate ~ 50 wt% of BNNTs in high density polyethylene
(HDPE). This process involves synthesizing millimeter-long
vertically aligned BNNTs, densifying the nanotubes to
high-volume fractions, and infusing the nanotubes with HDPE
while applying heat and pressure. The BNNT-HDPE
nanocomposite was tested for its neutron radiation
shielding properties at NASA Langley Research Center’s
neutron radiation exposure lab. Radiation shielding
properties of the BNNT-HDPE nanocomposite showed a ~10X
improvement in neutron shielding compared to the same areal
density/mass of HDPE
ECLSS Trace Contaminant Control Testing
Get PDFDaniela Barajas Ivey, Vast Space LLC, United StatesAndrew Irby, Vast Space LLC, United StatesPhoebe Henson, Vast Space LLC, United StatesGrady Hofstetter, Vast Space LLC, United StatesEnrique Portillo, Vast Space LLC, United StatesJennifer G. Williams, NASA Marshall Space Flight Center (MSFC), United StatesStanton Woodard, NASA Marshall Space Flight Center (MSFC), United StatesTrent Tran, NASA Marshall Space Flight Center (MSFC), United StatesAdrian L. Johnson, NASA Marshall Space Flight Center (MSFC), United StatesRobert L. Newton, NASA Marshall Space Flight Center (MSFC), United StatesJay L. Perry, Life Support Systems Technical Consultant, United StatesICES305: Environmental Control of Commercial and
Exploration SpacecraftThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Vast is focused on designing and launching next-generation
commercial space stations in Low Earth Orbit (LEO) with
induced artificial gravity. A key aspect of any
long-duration space station is maintaining a safe, healthy
cabin environment. Among the functions toward this end is
the trace contaminant control (TCC) system, which ensures
that levels of gaseous compounds emitted by human
metabolism, hardware offgassing, and vehicle systems
operations remain within safe limits. This paper details
the testing of a commercial TCC system that was executed
using in-house Vast capabilities in partnership with both
commercial vendors and the NASA Marshall Space Flight
Center’s (MSFC) Environmental Control and Life Support
Systems Development Branch. Subscale chemical challenge
performance testing was completed onsite at Vast and
system-level multi-component challenge testing was
completed at MSFC. Results demonstrate that the Vast TCC
system is able to maintain a safe and healthy atmosphere
for the Haven-1 mission for the designed loads
The Impact of Virtual School Education on Student Achievement in Texas: A Descriptive Analysis Through the Lens of Bronfenbrenner’s Ecological Systems Theory
Get PDFThis study examines the impact of full-time virtual public high school education in Texas on student outcomes, addressing three key research questions: (1) How did full-time virtual education in Texas impact the percentage of students passing end-of-year state achievement test or graduating compared to in-person instruction during the 2017- 2018 school year; (2) How did full-time virtual public high school education impact the percentage of students end-of-year state achievement scores and graduation rates compared to in-person instruction in Texas during the 2016-2017, 2017-2018, and 2018-2019 school years; and (3) How does this research, pre COVID-19 pandemic apply to the Texas education system today? Using Bronfenbrenner’s Ecological Systems Theory as a guiding framework, this study employed Ordinary Least Squares regression and Propensity Score Matching to analyze student performance in reading and math assessments and adjusted graduation rates. The results reveal that virtual education had no statistically significant effect on reading achievement but demonstrated a substantial negative impact on math scores and graduation rates. SES disadvantage, as measured by the percentage of students eligible for free or reduced-price lunch, emerged as a consistent predictor of lower outcomes across all measures, highlighting systemic inequities in education. Charter school status and staffing levels positively influenced performance, emphasizing the importance of institutional resources. These findings suggest that while virtual schooling offers opportunities for flexibility, it faces significant challenges in achieving parity with traditional schools. This study provides critical insights for policymakers and educators to improve virtual learning environments, address systemic inequities, and support diverse student populations in achieving equitable educational outcomes
Box 2, Folder 5, MGN Transcriptions Meditaciones Serias
Get PDFThe Boyd Carter Papers represent a significant archival collection housed in the Hispanic Studies Collection in Texas Tech University's CMLL building. Dr. Boyd Carter was a distinguished scholar of Latin American literature who was active from the 1940s to his death in 1980. He held professorships at the University of Nebraska, Southern Illinois University, and the University of Missouri before concluding his career at Texas Tech University (1978-1980). Upon joining TTU, Carter donated his extensive archive to the university, including rare books, microfilm collections, bibliographical notes, and periodicals focusing on Latin American literature from 1850-1950, with particular emphasis on the famed Mexican writer Manuel Gutiérrez Nájera