559 research outputs found
Rousseau o la irrupción de la autoconciencia
La comprensión historiográfica del lugar y de la significación del
pensamiento rousseauniano en el desarrollo general de la Filosofía Moderna
no deja de ser problemática: por un lado, debe considerarse la relación polémica
de Rousseau con el llamado “Enciclopedismo", por otro, sus acuerdos
y desacuerdos con el liberalismo político de la época. Sin embargo, la comprensión
logotectónica de la cosa propia del saber “filo-sófico" pone en evidencia
que con la posición histórica del pensamiento rousseauniano irrumpe
un saber fundamental acerca de la libertad, que resulta de una importancia
decisiva para el desenvolvimiento de la filosofía kantiana y de sus consecuencias.The historiographic understanding about the place and significance
of Rousseau´s thinking in the general development of modern philosophy
is problematic: on the one hand it is necessary to consider the controversial
relationship between Rousseau and the so called “Enciclopedism", on
the other hand, his agreements and disagreements with liberalism politics.
However, the logotectonic understanding of the proper matter of philosophic
wisdom shows that with the historic position of Rousseau´s thinking comes to
light a fundamental wisdom about freedom, that results for a decisive importance
to the development of Kant´s philosophy and its consequences.Fil: Boeder, Heribert
Peasants and plantations in the Mulanje and Thyolo Districts of southern Malawi, 1891-1951
African Studies Seminar series. Paper presented 21st June, 1982. Not to be quoted without the Author's permission.Although land and labour have been major themes in
Malawi's colonial history, class formation and the development
of the tea industry in the country's Southern Region
have received very little attention. This paper is a first
attempt to begin a discussion of these issues by focussing
on the Lomwe people who immigrated into Malwi from Mozambique
after 1890. Entering the country as refugees, most
Lomwe had to accept servility under Yao and Mang'an j a headmen
or as tenants on estates. As their numbers grew they formed
their own villages on Crown Land and became a peasantry
producing cotton and tobacco as cash crops and maize for
sale to Lomwe migrants employed as seasonal labourers on the
estates. The tea plantations themselves were inefficient
and poorly managed, depending largely on the exploitation of
their workers for profits
Investigation of HZETRN 2010 as a Tool for Single Event Effect Qualification of Avionics Systems
NASA's future missions are focused on long-duration deep space missions for human exploration which offers no options for a quick emergency return to Earth. The combination of long mission duration with no quick emergency return option leads to unprecedented spacecraft system safety and reliability requirements. It is important that spacecraft avionics systems for human deep space missions are not susceptible to Single Event Effect (SEE) failures caused by space radiation (primarily the continuous galactic cosmic ray background and the occasional solar particle event) interactions with electronic components and systems. SEE effects are typically managed during the design, development, and test (DD&T) phase of spacecraft development by using heritage hardware (if possible) and through extensive component level testing, followed by system level failure analysis tasks that are both time consuming and costly. The ultimate product of the SEE DD&T program is a prediction of spacecraft avionics reliability in the flight environment produced using various nuclear reaction and transport codes in combination with the component and subsystem level radiation test data. Previous work by Koontz, et al.1 utilized FLUKA, a Monte Carlo nuclear reaction and transport code, to calculate SEE and single event upset (SEU) rates. This code was then validated against in-flight data for a variety of spacecraft and space flight environments. However, FLUKA has a long run-time (on the order of days). CREME962, an easy to use deterministic code offering short run times, was also compared with FLUKA predictions and in-flight data. CREME96, though fast and easy to use, has not been updated in several years and underestimates secondary particle shower effects in spacecraft structural shielding mass. Thus, this paper will investigate the use of HZETRN 20103, a fast and easy to use deterministic transport code, similar to CREME96, that was developed at NASA Langley Research Center primarily for flight crew ionizing radiation dose assessments. HZETRN 2010 includes updates to address secondary particle shower effects more accurately, and might be used as another tool to verify spacecraft avionics system reliability in space flight SEE environments
Space Radiation Analysis for the Mark III Spacesuit
NASA has continued the development of space systems by applying and integrating improved technologies that include safety issues, lightweight materials, and electronics. One such area is extravehicular (EVA) spacesuit development with the most recent Mark III spacesuit. In this paper the Mark III spacesuit is discussed in detail that includes the various components that comprise the spacesuit, materials and their chemical composition that make up the spacesuit, and a discussion of the 3-D CAD model of the Mark III spacesuit. In addition, the male (CAM) and female (CAF) computerized anatomical models are also discussed in detail. We combined the spacesuit and the human models, that is, we developed a method of incorporating the human models in the Mark III spacesuit and performed a ray-tracing technique to determine the space radiation shielding distributions for all of the critical body organs. These body organ shielding distributions include the BFO (Blood-Forming Organs), skin, eye, lungs, stomach, and colon, to name a few, for both the male and female. Using models of the trapped (Van Allen) proton and electron environments, radiation exposures were computed for a typical low earth orbit (LEO) EVA mission scenario including the geostationary (GEO) high electron environment. A radiation exposure assessment of these mission scenarios is made to determine whether or not the crew radiation exposure limits are satisfied, and if not, the additional shielding material that would be required to satisfy the crew limits
Ionizing Radiation Environment on the International Space Station: Performance vs. Expectations for Avionics and Material
The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported. Detailed consideration of the effects of both the natural and induced ionizing radiation environment during ISS design, development, and flight operations has produced a safe, efficient manned space platform that is largely immune to deleterious effects of the LEO ionizing radiation environment. The assumption of a small shielding mass for purposes of design and verification has been shown to be a valid worst-case approximation approach to design for reliability, though predicted dependences of single event effect (SEE) effects on latitude, longitude, SEP events, and spacecraft structural shielding mass are not observed. The Figure of Merit (FOM) method over predicts the rate for median shielding masses of about 10g/cm(exp 2) by only a factor of 3, while the Scott Effective Flux Approach (SEFA) method overestimated by about one order of magnitude as expected. The Integral Rectangular Parallelepiped (IRPP), SEFA, and FOM methods for estimating on-orbit (Single Event Upsets) SEU rates all utilize some version of the CREME-96 treatment of energetic particle interaction with structural shielding, which has been shown to underestimate the production of secondary particles in heavily shielded manned spacecraft. The need for more work directed to development of a practical understanding of secondary particle production in massive structural shielding for SEE design and verification is indicated. In contrast, total dose estimates using CAD based shielding mass distributions functions and the Shieldose Code provided a reasonable accurate estimate of accumulated dose in Grays internal to the ISS pressurized elements, albeit as a result of using worst-on-worst case assumptions (500 km altitude x 2) that compensate for ignoring both GCR and secondary particle production in massive structural shielding
Comparison and Validation of FLUKA and HZETRN as Tools for Investigating the Secondary Neutron Production in Large Space Vehicles
NASA's exploration goals are focused on deep space travel and Mars surface operations. To accomplish these goals, large structures will be necessary to transport crew and logistics in the initial stages, and NASA will need to keep the crew and the vehicle safe during transport and any surface activities. One of the major challenges of deep space travel is the space radiation environment and its impacts on the crew, the electronics, and the vehicle materials. The primary radiation from the sun (solar particle events) and from outside the solar system (galactic cosmic rays) interact with materials of the vehicle. These interactions lead to some of the primary radiation being absorbed, being modified, or producing secondary radiation (primarily neutrons). With all vehicles, the high energy primary radiation is of most concern. However, with larger vehicles that have large shielding masses, there is more opportunity for secondary radiation production, and this secondary radiation can be significant enough to cause concern. When considering surface operations, there is also a secondary radiation source from the surface of the planet, known as albedo, with neutrons being one of the most significant species. Given new vehicle designs for deep space and Mars missions, the secondary radiation environment and the implications of that environment is currently not well understood. Thus, several studies are necessary to fill the knowledge gaps of this secondary radiation environment. In this paper, we put forth the initial steps to increasing our understanding of neutron production from large vehicles by comparing the neutron production resulting from our radiation transport codes and providing a preliminary validation of our results against flight data. This paper will review the details of these results and discuss the finer points of the analysis
The Ionizing Radiation Environment on the International Space Station: Performance vs. Expectations for Avionics and Materials
The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported
Investigation of HZETRN 2010 as a Tool for Single Event Effect Qualification of Avionics Systems
NASA's future missions are focused on deep space for human exploration that do not provide a simple emergency return to Earth. In addition, the deep space environment contains a constant background Galactic Cosmic Ray (GCR) radiation exposure, as well as periodic Solar Particle Events (SPEs) that can produce intense amounts of radiation in a short amount of time. Given these conditions, it is important that the avionics systems for deep space human missions are not susceptible to Single Event Effects (SEE) that can occur from radiation interactions with electronic components. The typical process to minimizing SEE effects is through using heritage hardware and extensive testing programs that are very costly. Previous work by Koontz, et al. [1] utilized an analysis-based method for investigating electronic component susceptibility. In their paper, FLUKA, a Monte Carlo transport code, was used to calculate SEE and single event upset (SEU) rates. This code was then validated against in-flight data. In addition, CREME-96, a deterministic code, was also compared with FLUKA and in-flight data. However, FLUKA has a long run-time (on the order of days), and CREME-96 has not been updated in several years. This paper will investigate the use of HZETRN 2010, a deterministic transport code developed at NASA Langley Research Center, as another tool that can be used to analyze SEE and SEU rates. The benefits to using HZETRN over FLUKA and CREME-96 are that it has a very fast run time (on the order of minutes) and has been shown to be of similar accuracy as other deterministic and Monte Carlo codes when considering dose [2, 3, 4]. The 2010 version of HZETRN has updated its treatment of secondary neutrons and thus has improved its accuracy over previous versions. In this paper, the Linear Energy Transfer (LET) spectra are of interest rather than the total ionizing dose. Therefore, the LET spectra output from HZETRN 2010 will be compared with the FLUKA and in-flight data to validate HZETRN 2010 as a computational tool for SEE qualification by analysis. Furthermore, extrapolation of these data to interplanetary environments at 1 AU will be investigated to determine whether HZETRN 2010 can be used successfully and confidently for deep space mission analyses
Named But Not Known: Teaching And Assessing The Research-Writing Process
In lived experience, the two processes of secondary research and writing overlap and intertwine interminably, creating an overarching complex system as research becomes expressed in writing and writing generates new research. This classroom study explores the two processes as one—the research-writing process—through coding of student journal responses and assessment of student research papers. Analysis reveals students to be thoughtful but not yet as nuanced in their descriptions of their research process as much be desired. They more frequently discuss writing with weaknesses in their research process than with research strengths. Further findings indicate that although it is difficult to assess a research course learning outcome, library faculty can be assessment raters with as much reliability and validity as writing faculty. Suggestions for improving the curriculum, pedagogy, and assessment of the research-writing process are provided as well as ideas for future research
Looking to the Research Paper and Beyond: Information Literacy and Rhetorical/Composition Perspectives on Student Research and Writing Processes
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